Long-term cathode performance and the microbial communities that develop in microbial fuel cells fed different fermentation endproducts

KAUST Repository

Kiely, Patrick D.

2011-01-01

To better understand how cathode performance and substrates affected communities that evolved in these reactors over long periods of time, microbial fuel cells were operated for more than 1year with individual endproducts of lignocellulose fermentation (acetic acid, formic acid, lactic acid, succinic acid, or ethanol). Large variations in reactor performance were primarily due to the specific substrates, with power densities ranging from 835±21 to 62±1mW/m3. Cathodes performance degraded over time, as shown by an increase in power of up to 26% when the cathode biofilm was removed, and 118% using new cathodes. Communities that developed on the anodes included exoelectrogenic families, such as Rhodobacteraceae, Geobacteraceae, and Peptococcaceae, with the Deltaproteobacteria dominating most reactors. Pelobacter propionicus was the predominant member in reactors fed acetic acid, and it was abundant in several other MFCs. These results provide valuable insights into the effects of long-term MFC operation on reactor performance. © 2010 Elsevier Ltd.

Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition.

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Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

2010-07-15

The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed. 2010 Elsevier B.V. All rights reserved.

Direct fed microbial supplementation repartitions host energy to the immune system.

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Qiu, R; Croom, J; Ali, R A; Ballou, A L; Smith, C D; Ashwell, C M; Hassan, H M; Chiang, C-C; Koci, M D

2012-08-01

Direct fed microbials and probiotics are used to promote health in livestock and poultry; however, their mechanism of action is still poorly understood. We previously reported that direct fed microbial supplementation in young broilers reduced ileal respiration without changing whole-body energy expenditure. The current studies were conducted to further investigate the effects of a direct fed microbial on energy metabolism in different tissues of broilers. One hundred ninety-two 1-d-old broiler chicks (16 chicks/pen) were randomly assigned to 2 dietary groups: standard control starter diet (CSD) and CSD plus direct fed microbial (DFMD; 0.3%) with 6 pens/treatment. Body weight, feed consumption, whole-body energy expenditure, organ mass, tissue respiration rates, and peripheral blood mononuclear cell (PBMC) ATP concentrations were measured to estimate changes in energy metabolism. No differences in whole body energy expenditure or BW gain were observed; however, decreased ileal O(2) respiration (P energy consumption by PBMC corresponded with an altered immune response, broilers were immunized with sheep red blood cells (SRBC) and assayed for differences in their humoral response. The DFMD-fed broilers had a faster rate of antigen specific IgG production (P direct fed microbial used in this study resulted in energy re-partitioning to the immune system and an increase in antibody production independent of changes in whole body metabolism or growth performance.

Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell.

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Timmers, Ruud A; Rothballer, Michael; Strik, David P B T B; Engel, Marion; Schulz, Stephan; Schloter, Michael; Hartmann, Anton; Hamelers, Bert; Buisman, Cees

2012-04-01

The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) were located on the root surfaces, but they were more abundant colonising the graphite granular electrode. Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, indicating that the current was probably generated via the hydrolysis of cellulose. Due to the presence of oxygen and nitrate, short-chain fatty acid-utilising denitrifiers were the major competitors for the electron donor. Acetate-utilising methanogens played a minor role in the competition for electron donor, probably due to the availability of graphite granules as electron acceptors.

Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

Energy Technology Data Exchange (ETDEWEB)

Timmers, Ruud A.; Strik, David P.B.T.B.; Hamelers, Bert; Buisman, Cees [Wageningen Univ. (Netherlands). Sub-dept. of Environmental Technology; Rothballer, Michael; Hartmann, Anton [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg (Germany). Dept. Microbe-Plant Interactions; Engel, Marion; Schulz, Stephan; Schloter, Michael [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Neuherberg (Germany). Dept. Terrestrial Ecogenetics

2012-04-15

The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode-rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) were located on the root surfaces, but they were more abundant colonising the graphite granular electrode. Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, indicating that the current was probably generated via the hydrolysis of cellulose. Due to the presence of oxygen and nitrate, short-chain fatty acid-utilising denitrifiers were the major competitors for the electron donor. Acetate-utilising methanogens played a minor role in the competition for electron donor, probably due to the availability of graphite granules as electron acceptors. (orig.)

Rumen microbial changes in cattle fed diets with or without salinomycin.

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Olumeyan, D B; Nagaraja, T G; Miller, G W; Frey, R A; Boyer, J E

1986-02-01

Four rumen-fistulated steers, randomly assigned to two groups (control and salinomycin fed) were used to monitor the changes in rumen microbial populations and volatile fatty acids (VFA) concentrations associated with feeding salinomycin (0.22 mg X kg-1 X day-1). Steers were adapted to an alfalfa hay and grain (80:20) diet before supplementing the diet with salinomycin, and then the diet was changed to 50:50 and 20:80 ratios of alfalfa hay to grain at 2-week intervals. Rumen samples for total and selective enumeration of anaerobic bacteria. VFA analysis, and enumeration of protozoa were collected during the 80:20 alfalfa hay-to-grain diet before salinomycin feeding, and during the 80:20, 50:50, and 20:80 hay-to-grain diets with salinomycin. At each sampling period, rumen samples were collected at 3 h after feeding on three consecutive days. Salinomycin feeding had no effect on rumen pH and total VFA concentration. The acetate-to-propionate ratio was significantly lower in salinomycin-fed steers than in the control. The molar proportion of butyrate increased in both control and salinomycin-fed steers. Total anaerobic bacterial counts were lower in salinomycin-fed steers than in the control steers after 8 weeks of salinomycin feeding. Salinomycin-resistant bacteria increased from 7.6 to 15.6% in salinomycin-fed steers but remained unchanged in control steers. Salinomycin had no effect on cellulolytic and lactate-utilizing bacteria, but the proportion of amylolytic bacteria was higher in salinomycin-fed steers than in control steers. The total number of protozoa decreased initially in salinomycin-fed steers. The initial reduction was due to reduced numbers of Entodinium species. Holotrichs were unaffected by salinomycin feeding.

Impact of temperature and substrate concentration on degradation rates of acetate, propionate and hydrogen and their links to microbial community structure.

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Zhao, Jing; Westerholm, Maria; Qiao, Wei; Yin, Dongmin; Bi, Shaojie; Jiang, Mengmeng; Dong, Renjie

2018-05-01

The present study investigates the conversion of acetate, propionate and hydrogen consumption linked to the microbial community structure and related to temperature and substrate concentration. Biogas reactors were continuously fed with coffee powder (20 g-COD/L) or acetate (20, 40, and 60 g-COD/L) and operated for 193 days at 37 °C or 55 °C conditions. Starting HRT was 23 days which was then reduced to 7 days. The kinetics of acetate and propionate degradation and hydrogen consumption rates were measured in batch assays. At HRT 7 days, the degradation rate of propionate was higher in thermophilic batches, while acetate degradation rate was higher at mesophilic conditions. The gaseous hydrogen consumption in acetate reactors increased proportionally with temperature and substrate concentration, while the dissolved hydrogen was not affected. The relative high abundance of hydrogentrophic methanogens indicated that the methanogenesis was directed towards the syntrophic acetate oxidation pathway at high acetate concentration and high temperature. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sorption and Microbial Uptake of Alanine, Glucose and Acetate in Soil

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Fischer, H.; Ingwersen, J.; Kuzyakov, Y.

2009-04-01

Low molecular weight organic substances (LMWOS), e. g. amino acids, sugars, and carboxylic acids, are C compounds that are most rapidly turned-over in the C cycle of soil. Despite of their importance it is still unknown how sorption to the soil matrix affects their turnover in soil solution. The goals of this study were (1) to describe the dynamics of the fluxes of LMWOS (10 µmol l-1) in various pools (dissolved, adsorbed, decomposed to CO2, incorporated into microbial biomass) and (2) to assess the LMWOS distribution in these pools in dependence of very wide range of concentration (0.01 to 1000 µmol l-1). Representatives of each LMWOS group (glucose for sugars, alanine for amino acids, Na-acetate for carboxylic acids) uniformly labeled with 14C were added to sterilized or non-sterilized soil and analyzed in dif-ferent compartments between 1 min and 5.6 hours after addition. LMWOS were almost completely taken up by microorganisms within the first 30 min. Microbial uptake was much faster than the physicochemical sorption (estimated in sterilized soil), which needed to reach quasi-equilibrium 60 min for alanine and about 400 min for glucose. Only sorption of acetate was instantaneous (>1 min). While for acetate the maximum sorption capacity was reached at 100 µmol l-1 no such maximum was found for glucose and alanine in the studied concentra-tion range. At the concentration of 100 µmol l-1, microbial decomposition after 4.5 h hours was higher for alanine (76.7±1.1%) than acetate (55.2±0.9%) and glucose (28.5±1.5%). On the contrary, incorporation into microbial biomass was higher for glucose (59.8±1.2%) than for acetate (23.4±5.9%) and alanine (5.2±2.8%). Within 10 to 500 µmol l-1 the pathways of the three LMWOS transformation changed: at 500 µmol l-1 alanine and acetate were less mineralized and more incorporated into microbial biomass than at 10 µmol l-1, while glucose incorporation decreased. Consequently, the concentrations of alanine, glucose, and

Denitrifying bacterial communities affect current production and nitrous oxide accumulation in a microbial fuel cell.

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Vilar-Sanz, Ariadna; Puig, Sebastià; García-Lledó, Arantzazu; Trias, Rosalia; Balaguer, M Dolors; Colprim, Jesús; Bañeras, Lluís

2013-01-01

The biocathodic reduction of nitrate in Microbial Fuel Cells (MFCs) is an alternative to remove nitrogen in low carbon to nitrogen wastewater and relies entirely on microbial activity. In this paper the community composition of denitrifiers in the cathode of a MFC is analysed in relation to added electron acceptors (nitrate and nitrite) and organic matter in the cathode. Nitrate reducers and nitrite reducers were highly affected by the operational conditions and displayed high diversity. The number of retrieved species-level Operational Taxonomic Units (OTUs) for narG, napA, nirS and nirK genes was 11, 10, 31 and 22, respectively. In contrast, nitrous oxide reducers remained virtually unchanged at all conditions. About 90% of the retrieved nosZ sequences grouped in a single OTU with a high similarity with Oligotropha carboxidovorans nosZ gene. nirS-containing denitrifiers were dominant at all conditions and accounted for a significant amount of the total bacterial density. Current production decreased from 15.0 A · m(-3) NCC (Net Cathodic Compartment), when nitrate was used as an electron acceptor, to 14.1 A · m(-3) NCC in the case of nitrite. Contrarily, nitrous oxide (N2O) accumulation in the MFC was higher when nitrite was used as the main electron acceptor and accounted for 70% of gaseous nitrogen. Relative abundance of nitrite to nitrous oxide reducers, calculated as (qnirS+qnirK)/qnosZ, correlated positively with N2O emissions. Collectively, data indicate that bacteria catalysing the initial denitrification steps in a MFC are highly influenced by main electron acceptors and have a major influence on current production and N2O accumulation.

Soil environmental conditions and microbial build-up mediate the effect of plant diversity on soil nitrifying and denitrifying enzyme activities in temperate grasslands.

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Xavier Le Roux

Full Text Available Random reductions in plant diversity can affect ecosystem functioning, but it is still unclear which components of plant diversity (species number - namely richness, presence of particular plant functional groups, or particular combinations of these and associated biotic and abiotic drivers explain the observed relationships, particularly for soil processes. We assembled grassland communities including 1 to 16 plant species with a factorial separation of the effects of richness and functional group composition to analyze how plant diversity components influence soil nitrifying and denitrifying enzyme activities (NEA and DEA, respectively, the abundance of nitrifiers (bacterial and archaeal amoA gene number and denitrifiers (nirK, nirS and nosZ gene number, and key soil environmental conditions. Plant diversity effects were largely due to differences in functional group composition between communities of identical richness (number of sown species, though richness also had an effect per se. NEA was positively related to the percentage of legumes in terms of sown species number, the additional effect of richness at any given legume percentage being negative. DEA was higher in plots with legumes, decreased with increasing percentage of grasses, and increased with richness. No correlation was observed between DEA and denitrifier abundance. NEA increased with the abundance of ammonia oxidizing bacteria. The effect of richness on NEA was entirely due to the build-up of nitrifying organisms, while legume effect was partly linked to modified ammonium availability and nitrifier abundance. Richness effect on DEA was entirely due to changes in soil moisture, while the effects of legumes and grasses were partly due to modified nitrate availability, which influenced the specific activity of denitrifiers. These results suggest that plant diversity-induced changes in microbial specific activity are important for facultative activities such as denitrification

Oral microbial profile discriminates breast-fed from formula-fed infants.

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Holgerson, Pernilla L; Vestman, Nelly R; Claesson, Rolf; Ohman, Carina; Domellöf, Magnus; Tanner, Anne C R; Hernell, Olle; Johansson, Ingegerd

2013-02-01

Little is known about the effect of diet on the oral microbiota of infants, although diet is known to affect the gut microbiota. The aims of the present study were to compare the oral microbiota in breast-fed and formula-fed infants, and investigate growth inhibition of streptococci by infant-isolated lactobacilli. A total of 207 mothers consented to participation of their 3-month-old infants. A total of 146 (70.5%) infants were exclusively and 38 (18.4%) partially breast-fed, and 23 (11.1%) were exclusively formula-fed. Saliva from all of their infants was cultured for Lactobacillus species, with isolate identifications from 21 infants. Lactobacillus isolates were tested for their ability to suppress Streptococcus mutans and S sanguinis. Oral swabs from 73 infants were analysed by the Human Oral Microbe Identification Microarray (HOMIM) and by quantitative polymerase chain reaction for Lactobacillus gasseri. Lactobacilli were cultured from 27.8% of exclusively and partially breast-fed infants, but not from formula-fed infants. The prevalence of 14 HOMIM-detected taxa, and total salivary lactobacilli counts differed by feeding method. Multivariate modelling of HOMIM-detected bacteria and possible confounders clustered samples from breast-fed infants separately from formula-fed infants. The microbiota of breast-fed infants differed based on vaginal or C-section delivery. Isolates of L plantarum, L gasseri, and L vaginalis inhibited growth of the cariogenic S mutans and the commensal S sanguinis: L plantarum >L gasseri >L vaginalis. The microbiota of the mouth differs between 3-month-old breast-fed and formula-fed infants. Possible mechanisms for microbial differences observed include species suppression by lactobacilli indigenous to breast milk.

Substrate-dependent denitrification of abundant probe-defined denitrifying bacteria in activated sludge.

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Morgan-Sagastume, Fernando; Nielsen, Jeppe Lund; Nielsen, Per Halkjaer

2008-11-01

The denitrification capacity of different phylogenetic bacterial groups was investigated on addition of different substrates in activated sludge from two nutrient-removal plants. Nitrate/nitrite consumption rates (CRs) were calculated from nitrate and nitrite biosensor, in situ measurements. The nitrate/nitrite CRs depended on the substrate added, and acetate alone or combined with other substrates yielded the highest rates (3-6 mg N gVSS(-1) h(-1)). The nitrate CRs were similar to the nitrite CRs for most substrates tested. The structure of the active denitrifying population was investigated using heterotrophic CO2 microautoradiography (HetCO2-MAR) and FISH. Probe-defined denitrifiers appeared as specialized substrate utilizers despite acetate being preferentially used by most of them. Azoarcus and Accumulibacter abundance in the two different sludges was related to differences in their substrate-specific nitrate/nitrite CRs. Aquaspirillum-related bacteria were the most abundant potential denitrifiers (c. 20% of biovolume); however, Accumulibacter (3-7%) and Azoarcus (2-13%) may have primarily driven denitrification by utilizing pyruvate, ethanol, and acetate. Activated sludge denitrification was potentially conducted by a diverse, versatile population including not only Betaproteobacteria (Aquaspirillum, Thauera, Accumulibacter, and Azoarcus) but also some Alphaproteobacteria and Gammaproteobacteria, as indicated by the assimilation of 14CO2 by these probe-defined groups with a complex substrate mixture as an electron donor and nitrite as an electron acceptor in HetCO2-MAR-FISH tests.

Evolving Microbial Communities in Cellulose-Fed Microbial Fuel Cell

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Renata Toczyłowska-Mamińska

2018-01-01

Full Text Available The abundance of cellulosic wastes make them attractive source of energy for producing electricity in microbial fuel cells (MFCs. However, electricity production from cellulose requires obligate anaerobes that can degrade cellulose and transfer electrons to the electrode (exoelectrogens, and thus most previous MFC studies have been conducted using two-chamber systems to avoid oxygen contamination of the anode. Single-chamber, air-cathode MFCs typically produce higher power densities than aqueous catholyte MFCs and avoid energy input for the cathodic reaction. To better understand the bacterial communities that evolve in single-chamber air-cathode MFCs fed cellulose, we examined the changes in the bacterial consortium in an MFC fed cellulose over time. The most predominant bacteria shown to be capable electron generation was Firmicutes, with the fermenters decomposing cellulose Bacteroidetes. The main genera developed after extended operation of the cellulose-fed MFC were cellulolytic strains, fermenters and electrogens that included: Parabacteroides, Proteiniphilum, Catonella and Clostridium. These results demonstrate that different communities evolve in air-cathode MFCs fed cellulose than the previous two-chamber reactors.

Characterization of a filamentous biofilm community established in a cellulose-fed microbial fuel cell

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Hotta Yasuaki

2008-01-01

Full Text Available Abstract Background Microbial fuel cells (MFCs are devices that exploit microorganisms to generate electric power from organic matter. Despite the development of efficient MFC reactors, the microbiology of electricity generation remains to be sufficiently understood. Results A laboratory-scale two-chamber microbial fuel cell (MFC was inoculated with rice paddy field soil and fed cellulose as the carbon and energy source. Electricity-generating microorganisms were enriched by subculturing biofilms that attached onto anode electrodes. An electric current of 0.2 mA was generated from the first enrichment culture, and ratios of the major metabolites (e.g., electric current, methane and acetate became stable after the forth enrichment. In order to investigate the electrogenic microbial community in the anode biofilm, it was morphologically analyzed by electron microscopy, and community members were phylogenetically identified by 16S rRNA gene clone-library analyses. Electron microscopy revealed that filamentous cells and rod-shaped cells with prosthecae-like filamentous appendages were abundantly present in the biofilm. Filamentous cells and appendages were interconnected via thin filaments. The clone library analyses frequently detected phylotypes affiliated with Clostridiales, Chloroflexi, Rhizobiales and Methanobacterium. Fluorescence in-situ hybridization revealed that the Rhizobiales population represented rod-shaped cells with filamentous appendages and constituted over 30% of the total population. Conclusion Bacteria affiliated with the Rhizobiales constituted the major population in the cellulose-fed MFC and exhibited unique morphology with filamentous appendages. They are considered to play important roles in the cellulose-degrading electrogenic community.

Mathematical Modeling of Nitrous Oxide Production during Denitrifying Phosphorus Removal Process.

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Liu, Yiwen; Peng, Lai; Chen, Xueming; Ni, Bing-Jie

2015-07-21

A denitrifying phosphorus removal process undergoes frequent alternating anaerobic/anoxic conditions to achieve phosphate release and uptake, during which microbial internal storage polymers (e.g., Polyhydroxyalkanoate (PHA)) could be produced and consumed dynamically. The PHA turnovers play important roles in nitrous oxide (N2O) accumulation during the denitrifying phosphorus removal process. In this work, a mathematical model is developed to describe N2O dynamics and the key role of PHA consumption on N2O accumulation during the denitrifying phosphorus removal process for the first time. In this model, the four-step anoxic storage of polyphosphate and four-step anoxic growth on PHA using nitrate, nitrite, nitric oxide (NO), and N2O consecutively by denitrifying polyphosphate accumulating organisms (DPAOs) are taken into account for describing all potential N2O accumulation steps in the denitrifying phosphorus removal process. The developed model is successfully applied to reproduce experimental data on N2O production obtained from four independent denitrifying phosphorus removal study reports with different experimental conditions. The model satisfactorily describes the N2O accumulation, nitrogen reduction, phosphate release and uptake, and PHA dynamics for all systems, suggesting the validity and applicability of the model. The results indicated a substantial role of PHA consumption in N2O accumulation due to the relatively low N2O reduction rate by using PHA during denitrifying phosphorus removal.

Set anode potentials affect the electron fluxes and microbial community structure in propionate-fed microbial electrolysis cells

KAUST Repository

Rao, Hari Ananda

2016-12-09

Anode potential has been shown to be a critical factor in the rate of acetate removal in microbial electrolysis cells (MECs), but studies with fermentable substrates and set potentials are lacking. Here, we examined the impact of three different set anode potentials (SAPs; −0.25, 0, and 0.25 V vs. standard hydrogen electrode) on the electrochemical performance, electron flux to various sinks, and anodic microbial community structure in two-chambered MECs fed with propionate. Electrical current (49–71%) and CH4 (22.9–41%) were the largest electron sinks regardless of the potentials tested. Among the three SAPs tested, 0 V showed the highest electron flux to electrical current (71 ± 5%) and the lowest flux to CH4 (22.9 ± 1.2%). In contrast, the SAP of −0.25 V had the lowest electron flux to current (49 ± 6%) and the highest flux to CH4 (41.1 ± 2%). The most dominant genera detected on the anode of all three SAPs based on 16S rRNA gene sequencing were Geobacter, Smithella and Syntrophobacter, but their relative abundance varied among the tested SAPs. Microbial community analysis implies that complete degradation of propionate in all the tested SAPs was facilitated by syntrophic interactions between fermenters and Geobacter at the anode and ferementers and hydrogenotrophic methanogens in suspension.

In situ acetate separation in microbial electrosynthesis from CO

NARCIS (Netherlands)

Bajracharya, Suman; Burg, van den Bart; Vanbroekhoven, Karolien; Wever, De Heleen; Buisman, Cees J.N.; Pant, Deepak; Strik, David P.B.T.B.

2017-01-01

Bioelectrochemical reduction of carbon dioxide (CO₂) to multi-carbon organic compounds particularly acetate has been achieved in microbial electrosynthesis (MES) using the reducing equivalents produced at the electrically polarized cathode. MES based on CO₂ reduction

Identification of the autotrophic denitrifying community in nitrate removal reactors by DNA-stable isotope probing.

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Xing, Wei; Li, Jinlong; Cong, Yuan; Gao, Wei; Jia, Zhongjun; Li, Desheng

2017-04-01

Autotrophic denitrification has attracted increasing attention for wastewater with insufficient organic carbon sources. Nevertheless, in situ identification of autotrophic denitrifying communities in reactors remains challenging. Here, a process combining micro-electrolysis and autotrophic denitrification with high nitrate removal efficiency was presented. Two batch reactors were fed organic-free nitrate influent, with H 13 CO 3 - and H 12 CO 3 - as inorganic carbon sources. DNA-based stable-isotope probing (DNA-SIP) was used to obtain molecular evidence for autotrophic denitrifying communities. The results showed that the nirS gene was strongly labeled by H 13 CO 3 - , demonstrating that the inorganic carbon source was assimilated by autotrophic denitrifiers. High-throughput sequencing and clone library analysis identified Thiobacillus-like bacteria as the most dominant autotrophic denitrifiers. However, 88% of nirS genes cloned from the 13 C-labeled "heavy" DNA fraction showed low similarity with all culturable denitrifiers. These findings provided functional and taxonomical identification of autotrophic denitrifying communities, facilitating application of autotrophic denitrification process for wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Metabolic modelling of polyhydroxyalkanoate copolymers production by mixed microbial cultures

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Reis Maria AM

2008-07-01

Full Text Available Abstract Background This paper presents a metabolic model describing the production of polyhydroxyalkanoate (PHA copolymers in mixed microbial cultures, using mixtures of acetic and propionic acid as carbon source material. Material and energetic balances were established on the basis of previously elucidated metabolic pathways. Equations were derived for the theoretical yields for cell growth and PHA production on mixtures of acetic and propionic acid as functions of the oxidative phosphorylation efficiency, P/O ratio. The oxidative phosphorylation efficiency was estimated from rate measurements, which in turn allowed the estimation of the theoretical yield coefficients. Results The model was validated with experimental data collected in a sequencing batch reactor (SBR operated under varying feeding conditions: feeding of acetic and propionic acid separately (control experiments, and the feeding of acetic and propionic acid simultaneously. Two different feast and famine culture enrichment strategies were studied: (i either with acetate or (ii with propionate as carbon source material. Metabolic flux analysis (MFA was performed for the different feeding conditions and culture enrichment strategies. Flux balance analysis (FBA was used to calculate optimal feeding scenarios for high quality PHA polymers production, where it was found that a suitable polymer would be obtained when acetate is fed in excess and the feeding rate of propionate is limited to ~0.17 C-mol/(C-mol.h. The results were compared with published pure culture metabolic studies. Conclusion Acetate was more conducive toward the enrichment of a microbial culture with higher PHA storage fluxes and yields as compared to propionate. The P/O ratio was not only influenced by the selected microbial culture, but also by the carbon substrate fed to each culture, where higher P/O ratio values were consistently observed for acetate than propionate. MFA studies suggest that when mixtures of

Effects of hydraulic retention time on anaerobic hydrogenation performance and microbial ecology of bioreactors fed with glucose-peptone and starch-peptone

Energy Technology Data Exchange (ETDEWEB)

Li, Shiue-Lin; Chao, Yu-Chieh; Wang, Yu-Hsuan; Hsiao, Chia-Jung; Bai, Ming-Der [Department of Environmental Engineering, National Cheng-Kung University, No. 1, University Road, Tainan 701 (China); Whang, Liang-Ming; Wang, Yung-Fu; Cheng, Sheng-Shung [Department of Environmental Engineering, National Cheng-Kung University, No. 1, University Road, Tainan 701 (China); Sustainable Environment Research Center (SERC), National Cheng-Kung University, No. 1, University Road, Tainan 701 (China); Tseng, I.-Cheng [Sustainable Environment Research Center (SERC), National Cheng-Kung University, No. 1, University Road, Tainan 701 (China); Department of Life Science, National Cheng-Kung University, No. 1, University Road, Tainan 701 (China)

2010-01-15

This study evaluated anaerobic hydrogenation performance and microbial ecology in bioreactors operated at different hydraulic retention time (HRT) conditions and fed with glucose-peptone (GP) and starch-peptone (SP). The maximum hydrogen production rates for GP- and SP-fed bioreactors were found to be 1247 and 412 mmol-H{sub 2}/L/d at HRT of 2 and 3 h, respectively. At HRT > 8 h, hydrogen consumption due to peptone fermentation could occur and thus reduced hydrogen yield from carbohydrate fermentation. Results of cloning/sequencing and denaturant gradient gel electrophoresis (DGGE) indicated that Clostridium sporogenes and Clostridium celerecrescens were dominant hydrogen-producing bacteria in the GP-fed bioreactor, presumably due to their capability on protein hydrolysis. In the SP-fed bioreactor, Lactobacillus plantarum, Propionispira arboris, and Clostridium butyricum were found to be dominant populations, but the presence of P. arboris at HRT > 3 h might be responsible for a lower hydrogen yield from starch fermentation. As a result, optimizing HRT operation for bioreactors was considered an important asset in order to minimize hydrogen-consuming activities and thus maximize net hydrogen production. The limitation of simple parameters such as butyrate to acetate ratio (B/A ratio) in predicting hydrogen production was recognized in this study for bioreactors fed with multiple substrates. It is suggested that microbial ecology analysis, in addition to chemical analysis, should be performed when complex substrates and mixed cultures are used in hydrogen-producing bioreactors. (author)

Reduction of produced elementary sulfur in denitrifying sulfide removal process.

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Zhou, Xu; Liu, Lihong; Chen, Chuan; Ren, Nanqi; Wang, Aijie; Lee, Duu-Jong

2011-05-01

Denitrifying sulfide removal (DSR) processes simultaneously convert sulfide, nitrate, and chemical oxygen demand from industrial wastewater into elemental sulfur, dinitrogen gas, and carbon dioxide, respectively. The failure of a DSR process is signaled by high concentrations of sulfide in reactor effluent. Conventionally, DSR reactor failure is blamed for overcompetition for heterotroph to autotroph communities. This study indicates that the elementary sulfur produced by oxidizing sulfide that is a recoverable resource from sulfide-laden wastewaters can be reduced back to sulfide by sulfur-reducing Methanobacterium sp. The Methanobacterium sp. was stimulated with excess organic carbon (acetate) when nitrite was completely consumed by heterotrophic denitrifiers. Adjusting hydraulic retention time of a DSR reactor when nitrite is completely consumed provides an additional control variable for maximizing DSR performance.

Growing and laying performance of Japanese quail fed diet supplemented with different concentrations of acetic acid

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Youssef A. Attia

2013-04-01

Full Text Available In order to evaluate the effect of acetic acid on growing and laying performance of Japanese Quail (JQ, 180 15-day-old JQ were divided into 4 groups. During the growing (15-42 days of age and laying (43-84 days of age periods, the groups fed the same basal diets supplemented with 0, 1.5, 3 and 6% of acetic acid. Each diet was fed to five replicates of 9 JQ (3 males:6 females during the growing period. During the laying period, 128 birds were housed in 32 cages (4 birds per cage, 1 male and 3 females, 8 replicates per treatment. Birds were housed in wire cages (46L×43W×20H cm in an open room. Acetic acid supplementation at 3% in the diets significantly increased the growth and laying rate and the Haugh unit score. The liver percentage significantly decreased with acetic acid at 6%. Acetic acid at 3% significantly increased hemoglobin concentrations at 6 weeks of age and increased weight of day old chicks hatched. Acetic acid affected the immune system as manifested by an excess of cellular reactions in the intestine as well as lymphoid hyperplasia in the spleen tissue. Degenerative changes in the covering epithelium of the intestinal villi were noted at the 6% concentration of acetic acid. Hepatocyte vacuolation and fatty changes were also observed at this concentration of treatment. In conclusion, 3% acetic acid may be used as a feed supplement for JQ during the growing and laying period to improve the productive performance.

Meta-Transcriptomic Analysis of a Chromate-Reducing Aquifer Microbial Community

Science.gov (United States)

Beller, H. R.; Brodie, E. L.; Han, R.; Karaoz, U.

2010-12-01

A major challenge for microbial ecology that has become more tractable in the advent of new molecular techniques is characterizing gene expression in complex microbial communities. We are using meta-transcriptomic analysis to characterize functional changes in an aquifer-derived, chromate-reducing microbial community as it transitions through various electron-accepting conditions. We inoculated anaerobic microcosms with groundwater from the Cr-contaminated Hanford 100H site and supplemented them with lactate and electron acceptors present at the site, namely, nitrate, sulfate, and Fe(III). The microcosms progressed successively through various electron-accepting conditions (e.g., denitrifying, sulfate-reducing, and ferric iron-reducing conditions, as well as nitrate-dependent, chemolithotrophic Fe(II)-oxidizing conditions). Cr(VI) was rapidly reduced initially and again upon further Cr(VI) amendments. Extensive geochemical sampling and analysis (e.g., lactate, acetate, chloride, nitrate, nitrite, sulfate, dissolved Cr(VI), total Fe(II)), RNA/DNA harvesting, and PhyloChip analyses were conducted. Methods were developed for removal of rRNA from total RNA in preparation for meta-transcriptome sequencing. To date, samples representing denitrifying and fermentative/sulfate-reducing conditions have been sequenced using 454 Titanium technology. Of the non-rRNA related reads for the denitrifying sample (which was also actively reducing chromate), ca. 8% were associated with denitrification and ca. 0.9% were associated with chromate resistance/transport, in contrast to the fermentative/sulfate-reducing sample (in which chromate had already been reduced), which had zero reads associated with either of these categories but many predicted proteins associated with sulfate-reducing bacteria. We observed sequences for key functional transcripts that were unique at the nucleotide level compared to the GenBank non-redundant database [such as L-lactate dehydrogenase (iron

Effects of bacterial direct-fed microbials on ruminal characteristics, methane emission, and milk fatty acid composition in cows fed high- or low-starch diets.

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Philippeau, C; Lettat, A; Martin, C; Silberberg, M; Morgavi, D P; Ferlay, A; Berger, C; Nozière, P

2017-04-01

This study investigated the effects of bacterial direct-fed microbials (DFM) on ruminal fermentation and microbial characteristics, methane (CH 4 ) emission, diet digestibility, and milk fatty acid (FA) composition in dairy cows fed diets formulated to induce different ruminal volatile fatty acid (VFA) profiles. Eight ruminally cannulated dairy cows were divided into 2 groups based on parity, days in milk, milk production, and body weight. Cows in each group were fed either a high-starch (38%, HS) or a low-starch (2%, LS) diet in a 55:45 forage-to-concentrate ratio on a dry matter (DM) basis. For each diet, cows were randomly assigned to 1 of 4 treatments in a Latin square design of (1) control (CON); (2) Propionibacterium P63 (P63); (3) P63 plus Lactobacillus plantarum 115 (P63+Lp); (4) P63 plus Lactobacillus rhamnosus 32 (P63+Lr). Strains of DFM were administered at 10 10 cfu/d. Methane emission (using the sulfur hexafluoride tracer technique), total-tract digestibility, dry matter intake, and milk production and composition were quantified in wk 3. Ruminal fermentation and microbial characteristics were measured in wk 4. Data were analyzed using the mixed procedure of SAS (SAS Institute Inc., Cary, NC). The 2 diets induced different ruminal VFA profiles, with a greater proportion of propionate at the expense of acetate and butyrate for the HS diet. Greater concentrations of total bacteria and selected bacterial species of methanogenic Archaea were reported for the HS diet, whereas the protozoa concentration in HS decreased. For both diets, bacterial DFM supplementation raised ruminal pH (+0.18 pH units, on average) compared with CON. Irrespective of diet, P63+Lp and P63+Lr increased ruminal cellulase activity (3.8-fold, on average) compared with CON, but this effect was not associated with variations in ruminal microbial numbers. Irrespective of diet, no effect of bacterial DFM on ruminal VFA was observed. For the LS diet, supplementing cows with P63+Lr tended

Effect of nitrate, acetate and hydrogen on native perchlorate-reducing microbial communities and their activity in vadose soil

Science.gov (United States)

Nozawa-Inoue, Mamie; Jien, Mercy; Yang, Kun; Rolston, Dennis E.; Hristova, Krassimira R.; Scow, Kate M.

2011-01-01

Effect of nitrate, acetate and hydrogen on native perchlorate-reducing bacteria (PRB) was examined by conducting microcosm tests using vadose soil collected from a perchlorate-contaminated site. The rate of perchlorate reduction was enhanced by hydrogen amendment and inhibited by acetate amendment, compared to unamendment. Nitrate was reduced before perchlorate in all amendments. In hydrogen-amended and unamended soils, nitrate delayed perchlorate reduction, suggesting the PRB preferentially use nitrate as an electron acceptor. In contrast, nitrate eliminated the inhibitory effect of acetate amendment on perchlorate reduction and increased the rate and the extent, possibly because the preceding nitrate reduction/denitrification decreased the acetate concentration which was inhibitory to the native PRB. In hydrogen-amended and unamended soils, perchlorate reductase gene (pcrA) copies, representing PRB densities, increased with either perchlorate or nitrate reduction, suggesting either perchlorate or nitrate stimulates growth of the PRB. In contrast, in acetate-amended soil pcrA increased only when perchlorate was depleted: a large portion of the PRB may have not utilized nitrate in this amendment. Nitrate addition did not alter the distribution of the dominant pcrA clones in hydrogen-amended soil, likely because of the functional redundancy of PRB as nitrate-reducers/denitrifiers, whereas acetate selected different pcrA clones from those with hydrogen amendment. PMID:21284679

Functional consortium for denitrifying sulfide removal process.

Science.gov (United States)

Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

2010-03-01

Denitrifying sulfide removal (DSR) process simultaneously converts sulfide, nitrate, and chemical oxygen demand from industrial wastewaters to elemental sulfur, nitrogen gas, and carbon dioxide, respectively. This investigation utilizes a dilution-to-extinction approach at 10(-2) to 10(-6) dilutions to elucidate the correlation between the composition of the microbial community and the DSR performance. In the original suspension and in 10(-2) dilution, the strains Stenotrophomonas sp., Thauera sp., and Azoarcus sp. are the heterotrophic denitrifiers and the strains Paracoccus sp. and Pseudomonas sp. are the sulfide-oxidizing denitrifers. The 10(-4) dilution is identified as the functional consortium for the present DSR system, which comprises two functional strains, Stenotrophomonas sp. strain Paracoccus sp. At 10(-6) dilution, all DSR performance was lost. The functions of the constituent cells in the DSR granules were discussed based on data obtained using the dilution-to-extinction approach.

Nitrite survival and nitrous oxide production of denitrifying phosphorus removal sludges in long-term nitrite/nitrate-fed sequencing batch reactors.

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Wang, Yayi; Zhou, Shuai; Ye, Liu; Wang, Hong; Stephenson, Tom; Jiang, Xuxin

2014-12-15

Nitrite-based phosphorus (P) removal could be useful for innovative biological P removal systems where energy and carbon savings are a priority. However, using nitrite for denitrification may cause nitrous oxide (N2O) accumulation and emissions. A denitrifying nitrite-fed P removal system [Formula: see text] was successfully set up in a sequencing batch reactor (SBR) and was run for 210 days. The maximum pulse addition of nitrite to [Formula: see text] was 11 mg NO2(-)-N/L in the bulk, and a total of 34 mg NO2(-)-N/L of nitrite was added over three additions. Fluorescent in situ hybridization results indicated that the P-accumulating organisms (PAOs) abundance was 75 ± 1.1% in [Formula: see text] , approximately 13.6% higher than that in a parallel P removal SBR using nitrate [Formula: see text] . Type II Accumulibacter (PAOII) (unable to use nitrate as an electron acceptor) was the main PAOs species in [Formula: see text] , contributing 72% to total PAOs. Compared with [Formula: see text] , [Formula: see text] biomass had enhanced nitrite/free nitrous acid (FNA) endurance, as demonstrated by its higher nitrite denitrification and P uptake rates. N2O accumulated temporarily in [Formula: see text] after each pulse of nitrite. Peak N2O concentrations in the bulk for [Formula: see text] were generally 6-11 times higher than that in [Formula: see text] ; these accumulations were rapidly denitrified to nitrogen gases. N2O concentration increased rapidly in nitrate-cultivated biomass when 5 or 10 mg NO2(-)-N/L per pulse was added. Whereas, N2O accumulation did not occur in nitrite-cultivated biomass until up to 30 mg NO2(-)-N/L per pulse was added. Long-term acclimation to nitrite and pulse addition of nitrite in [Formula: see text] reduced the risk of nitrite accumulation, and mitigated N2O accumulation and emissions from denitrifying P removal by nitrite. Copyright © 2014 Elsevier Ltd. All rights reserved.

Abundance, composition and activity of denitrifier communities in metal polluted paddy soils

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Liu, Yuan; Liu, Yongzhuo; Zhou, Huimin; Li, Lianqing; Zheng, Jinwei; Zhang, Xuhui; Zheng, Jufeng; Pan, Genxing

2016-01-01

Denitrification is one of the most important soil microbial processes leading to the production of nitrous oxide (N2O). The potential changes with metal pollution in soil microbial community for N2O production and reduction are not well addressed. In this study, topsoil samples were collected both from polluted and non-polluted rice paddy fields and denitrifier communities were characterized with molecular fingerprinting procedures. All the retrieved nirK sequences could be grouped into neither α- nor β- proteobacteria, while most of the nosZ sequences were affiliated with α-proteobacteria. The abundances of the nirK and nosZ genes were reduced significantly in the two polluted soils. Thus, metal pollution markedly affected composition of both nirK and nosZ denitrifiers. While the total denitrifying activity and N2O production rate were both reduced under heavy metal pollution of the two sites, the N2O reduction rate showed no significant change. These findings suggest that N2O production activity could be sensitive to heavy metal pollution, which could potentially lead to a decrease in N2O emission in polluted paddies. Therefore, metal pollution could have potential impacts on soil N transformation and thus on N2O emission from paddy soils. PMID:26739424

Diversity and activity of denitrifiers of Chilean arid soil ecosystems

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Julieta eOrlando

2012-04-01

Full Text Available The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study, we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of

Diversity and activity of denitrifiers of chilean arid soil ecosystems.

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Orlando, Julieta; Carú, Margarita; Pommerenke, Bianca; Braker, Gesche

2012-01-01

The Chilean sclerophyllous matorral is a Mediterranean semiarid ecosystem affected by erosion, with low soil fertility, and limited by nitrogen. However, limitation of resources is even more severe for desert soils such as from the Atacama Desert, one of the most extreme arid deserts on Earth. Topsoil organic matter, nitrogen and moisture content were significantly higher in the semiarid soil compared to the desert soil. Although the most significant loss of biologically preferred nitrogen from terrestrial ecosystems occurs via denitrification, virtually nothing is known on the activity and composition of denitrifier communities thriving in arid soils. In this study we explored denitrifier communities from two soils with profoundly distinct edaphic factors. While denitrification activity in the desert soil was below detection limit, the semiarid soil sustained denitrification activity. To elucidate the genetic potential of the soils to sustain denitrification processes we performed community analysis of denitrifiers based on nitrite reductase (nirK and nirS) genes as functional marker genes for this physiological group. Presence of nirK-type denitrifiers in both soils was demonstrated but failure to amplify nirS from the desert soil suggests very low abundance of nirS-type denitrifiers shedding light on the lack of denitrification activity. Phylogenetic analysis showed a very low diversity of nirK with only three distinct genotypes in the desert soil which conditions presumably exert a high selection pressure. While nirK diversity was also limited to only few, albeit distinct genotypes, the semiarid matorral soil showed a surprisingly broad genetic variability of the nirS gene. The Chilean matorral is a shrub land plant community which form vegetational patches stabilizing the soil and increasing its nitrogen and carbon content. These islands of fertility may sustain the development and activity of the overall microbial community and of denitrifiers in particular.

Anode microbial communities produced by changing from microbial fuel cell to microbial electrolysis cell operation using two different wastewaters

KAUST Repository

Kiely, Patrick D.; Cusick, Roland; Call, Douglas F.; Selembo, Priscilla A.; Regan, John M.; Logan, Bruce E.

2011-01-01

Conditions in microbial fuel cells (MFCs) differ from those in microbial electrolysis cells (MECs) due to the intrusion of oxygen through the cathode and the release of H2 gas into solution. Based on 16S rRNA gene clone libraries, anode communities in reactors fed acetic acid decreased in species richness and diversity, and increased in numbers of Geobacter sulfurreducens, when reactors were shifted from MFCs to MECs. With a complex source of organic matter (potato wastewater), the proportion of Geobacteraceae remained constant when MFCs were converted into MECs, but the percentage of clones belonging to G. sulfurreducens decreased and the percentage of G. metallireducens clones increased. A dairy manure wastewater-fed MFC produced little power, and had more diverse microbial communities, but did not generate current in an MEC. These results show changes in Geobacter species in response to the MEC environment and that higher species diversity is not correlated with current. © 2010 Elsevier Ltd.

Warming-induced changes in denitrifier community structure modulate the ability of phototrophic river biofilms to denitrify

Energy Technology Data Exchange (ETDEWEB)

Boulêtreau, Stéphanie, E-mail: stephanie.bouletreau@univ-tlse3.fr [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Lyautey, Emilie [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Dubois, Sophie [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France); Compin, Arthur [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Delattre, Cécile; Touron-Bodilis, Aurélie [EDF Recherche et Développement, LNHE (Laboratoire National d' Hydraulique et Environnement), 6 quai Watier, F-78401 Chatou (France); Mastrorillo, Sylvain [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Garabetian, Frédéric [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France)

2014-01-01

Microbial denitrification is the main nitrogen removing process in freshwater ecosystems. The aim of this study was to show whether and how water warming (+ 2.5 °C) drives bacterial diversity and structuring and how bacterial diversity affects denitrification enzymatic activity in phototrophic river biofilms (PRB). We used water warming associated to the immediate thermal release of a nuclear power plant cooling circuit to produce natural PRB assemblages on glass slides while testing 2 temperatures (mean temperature of 17 °C versus 19.5 °C). PRB were sampled at 2 sampling times during PRB accretion (6 and 21 days) in both temperatures. Bacterial community composition was assessed using ARISA. Denitrifier community abundance and denitrification gene mRNA levels were estimated by q-PCR and qRT-PCR, respectively, of 5 genes encoding catalytic subunits of the denitrification key enzymes. Denitrification enzyme activity (DEA) was measured by the acetylene-block assay at 20 °C. A mean water warming of 2.5 °C was sufficient to produce contrasted total bacterial and denitrifier communities and, therefore, to affect DEA. Indirect temperature effect on DEA may have varied between sampling time, increasing by up to 10 the denitrification rate of 6-day-old PRB and decreasing by up to 5 the denitrification rate of 21-day-old PRB. The present results suggest that indirect effects of warming through changes in bacterial community composition, coupled to the strong direct effect of temperature on DEA already demonstrated in PRB, could modulate dissolved nitrogen removal by denitrification in rivers and streams. - Highlights: •We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5 °C. •We compared their denitrifiers' structuring and functioning in 6d- and 21d-old biofilms. •A difference of 2.5 °C produced contrasted denitrifier communities. •The indirect temperature effect on denitrification activity shifted between biofilm age. �

Ground Juniperus pinchotii and urea in supplements fed to Rambouillet ewe lambs Part 2: Ewe lamb rumen microbial communities.

Science.gov (United States)

Ishaq, S L; Yeoman, C J; Whitney, T R

2017-10-01

This study evaluated effects of ground redberry juniper () and urea in dried distillers grains with solubles-based supplements fed to Rambouillet ewe lambs ( = 48) on rumen physiological parameters and bacterial diversity. In a randomized study (40 d), individually-penned lambs were fed ground sorghum-sudangrass hay and of 1 of 8 supplements (6 lambs/treatment; 533 g/d; as-fed basis) in a 4 × 2 factorial design with 4 concentrations of ground juniper (15%, 30%, 45%, or 60% of DM) and 2 levels of urea (1% or 3% of DM). Increasing juniper resulted in minor changes in microbial β-diversity (PERMANOVA, pseudo F = 1.33, = 0.04); however, concentrations of urea did not show detectable broad-scale differences at phylum, family, or genus levels according to ANOSIM ( > 0.05), AMOVA ( > 0.10), and PERMANOVA ( > 0.05). Linear discriminant analysis indicated some genera were specific to certain dietary treatments ( < 0.05), though none of these genera were present in high abundance; high concentrations of juniper were associated with and , low concentrations of urea were associated with , and high concentrations of urea were associated with and . were decreased by juniper and urea. , , and increased with juniper and were positively correlated (Spearman's, < 0.05) with each other but not to rumen factors, suggesting a symbiotic interaction. Overall, there was not a juniper × urea interaction for total VFA, VFA by concentration or percent total, pH, or ammonia ( 0.29). When considering only percent inclusion of juniper, ruminal pH and proportion of acetic acid linearly increased ( < 0.001) and percentage of butyric acid linearly decreased ( = 0.009). Lamb ADG and G:F were positively correlated with (Spearman's, < 0.05) and negatively correlated with Synergistaceae, the BS5 group, and Lentisphaerae. Firmicutes were negatively correlated with serum urea nitrogen, ammonia, total VFA, total acetate, and total propionate. Overall, modest differences in bacterial diversity among

Microbial characteristics of purple paddy soil in response to Pb pollution.

Science.gov (United States)

Jiang, Qiu-Ju; Zhang, Yue-Qiang; Zhang, La-Mei; Zhou, Xin-Bin; Shi, Xiao-Jun

2014-05-01

The study focused on the change of microbial characteristics affected by Plumbum pollution with purple paddy soil in an incubation experiment. The results showed that low concentration of Plumbum had little effect on most of microbial amounts, biological activity and enzymatic activity. However, denitrifying activity was inhibited severely, and inhibition rate was up to 98%. Medium and high concentration of Plumbum significantly reduced the amounts and activity of all microorganisms and enzymatic activity, which increased with incubation time. Negative correlations were found between Plumbum concentrations and microbial amounts, biological activity and enzymatic activities except fungi and actinomyces. Thus they can be used to indicate the Plumbum pollution levels to some extent. LD(50) of denitrifying bacteria (DB) and ED50 of denitrifying activity were 852mg/kg and 33.5mg/kg. Across all test soil microbes, denitrifying bacteria was most sensitive to Plumbum pollution in purple paddy soil. Value of early warning showed that anaerobic cellulose-decomposing bacteria (ACDB) and actinomyces were also sensitive to Plumbum pollution. We concluded that denitrifying activity, actinomyces, ACDB or DB can be chosen as predictor of Plumbum contamination in purple paddy soil.

Fed-batch culture for the direct conversion of cellulosic substrates to acetic acid/ethanol by Fusarium oxysporum

Energy Technology Data Exchange (ETDEWEB)

Kumar, P.K.R.; Singh, A.; Schuegerl, K. (Hannover Univ. (Germany). Inst. fuer Technische Chemie)

1991-01-01

The production of acetic acid/ethanol and hydrolytic enzymes from potato waste (cellulosic waste from potato starch industries) by Fusarium oxysporum 841 was improved considerably by using fed-batch culture. In this, two types of feed policies were adopted consisting of different substrate concentrations and feeding times. In fed-batch culture, the enzymes tested, namely avicelase, CMCase, cellobiase and xylanase, showed significant improvements over batch fermentations with regard to enzyme titres and productivities. The maximum concentration, yield and productivity of acetic acid were 22.5 g litre{sup -1}, 0.38 g (g {sub strate}){sup -1} and 0.09 g litre{sup -1} h{sup -1}, respectively, and these values for ethanol were 5.7 g litre{sup -1}, 0.1 g (g substrate){sup -1} and 0.03 g litre{sup -1}h{sup -1}, respectively. (author).

Microbial process for the preparation of acetic acid as well as solvent for its extraction from the fermentation broth

Science.gov (United States)

Gaddy, James L.; Clausen, Edgar C.; Ko, Ching-Whan; Wade, Leslie E.; Wikstrom, Carl V.

2002-01-01

A modified water-immiscible solvent useful in the extraction of acetic acid from aqueous streams is a substantially pure mixture of isomers of highly branched di-alkyl amines. This solvent is substantially devoid of mono-alkyl amines and alcohols. Solvent mixtures formed of such a modified solvent with a desired cosolvent, preferably a low boiling hydrocarbon which forms an azeotrope with water are useful in the extraction of acetic acid from aqueous gaseous streams. An anaerobic microbial fermentation process for the production of acetic acid employs such solvents, under conditions which limit amide formation by the solvent and thus increase the efficiency of acetic acid recovery. Methods for the direct extraction of acetic acid and the extractive fermentation of acetic acid also employ the modified solvents and increase efficiency of acetic acid production. Such increases in efficiency are also obtained where the energy source for the microbial fermentation contains carbon dioxide and the method includes a carbon dioxide stripping step prior to extraction of acetic acid in solvent.

Soil C and N statuses determine the effect of maize inoculation by plant growth-promoting rhizobacteria on nitrifying and denitrifying communities.

Science.gov (United States)

Florio, Alessandro; Pommier, Thomas; Gervaix, Jonathan; Bérard, Annette; Le Roux, Xavier

2017-08-21

Maize inoculation by Azospirillum stimulates root growth, along with soil nitrogen (N) uptake and root carbon (C) exudation, thus increasing N use efficiency. However, inoculation effects on soil N-cycling microbial communities have been overlooked. We hypothesized that inoculation would (i) increase roots-nitrifiers competition for ammonium, and thus decrease nitrifier abundance; and (ii) increase roots-denitrifiers competition for nitrate and C supply to denitrifiers by root exudation, and thus limit or benefit denitrifiers depending on the resource (N or C) mostly limiting these microorganisms. We quantified (de)nitrifiers abundance and activity in the rhizosphere of inoculated and non-inoculated maize on 4 sites over 2 years, and ancillary soil variables. Inoculation effects on nitrification and nitrifiers (AOA, AOB) were not consistent between the three sampling dates. Inoculation influenced denitrifiers abundance (nirK, nirS) differently among sites. In sites with high C limitation for denitrifiers (i.e. limitation of denitrification by C > 66%), inoculation increased nirS-denitrifier abundance (up to 56%) and gross N 2 O production (up to 84%), likely due to increased root C exudation. Conversely, in sites with low C limitation (<47%), inoculation decreased nirS-denitrifier abundance (down to -23%) and gross N 2 O production (down to -18%) likely due to an increased roots-denitrifiers competition for nitrate.

Short communication: Effects of increasing protein and energy in the milk replacer with or without direct-fed microbial supplementation on growth and performance of preweaned Holstein calves.

Science.gov (United States)

Geiger, A J; Ward, S H; Williams, C C; Rude, B J; Cabrera, C J; Kalestch, K N; Voelz, B E

2014-11-01

Forty-four Holstein calves were fed a direct-fed microbial (DFM) and 1 of 2 milk replacers to evaluate calf performance and growth. Treatments were (1) a control milk replacer [22:20; 22% crude protein (CP) and 20% fat], (2) an accelerated milk replacer (27:10; 27% CP and 10% fat), (3) the control milk replacer with added DFM (22:20+D), and (4) the accelerated milk replacer with added DFM (27:10+D). Dry matter intake, rectal temperatures, respiration scores and rates, and fecal scores were collected daily. Body weight, hip and withers height, heart girth, blood, and rumen fluid samples were collected weekly. Effects of treatment, sex, week, and their interactions were analyzed. Calves fed an accelerated milk replacer, regardless of DFM supplementation, consumed more CP and metabolizable energy in the milk replacer. No treatment differences were found for starter intake or intake of neutral detergent fiber or acid detergent fiber in the starter. Calves fed the accelerated milk replacer had greater preweaning and weaning body weight compared with calves fed the control milk replacer. Average daily gain was greater during the preweaning period for calves fed the accelerated milk replacer, but the same pattern did not hold true during the postweaning period. Feed efficiency did not differ among treatments. Hip height tended to be and withers height and heart girth were greater at weaning for calves fed the accelerated milk replacer compared with calves fed the control milk replacer. Fecal scores were greatest in calves fed DFM. Overall acetate, propionate, butyrate, and n-valerate concentrations were lower in calves fed the accelerated milk replacer, but DFM did not have an effect. Rumen pH was not different. Blood metabolites were unaffected by DFM supplementation, but calves fed the accelerated milk replacer had increased partial pressure of CO2, bicarbonate, and total bicarbonate in the blood. Direct-fed microbial supplementation did not appear to benefit the calf

Abundance and Diversity of Denitrifying and Anammox Bacteria in Seasonally Hypoxic and Sulfidic Sediments of the Saline Lake Grevelingen

Science.gov (United States)

Lipsewers, Yvonne A.; Hopmans, Ellen C.; Meysman, Filip J. R.; Sinninghe Damsté, Jaap S.; Villanueva, Laura

2016-01-01

Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution) at three different locations before (March) and during summer hypoxia (August). The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers, and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen-, and sulfur cycling in Lake Grevelingen sediments. PMID:27812355

Abundance and diversity of denitrifying and anammox bacteria in seasonally hypoxic and sulfidic sediments of the saline Lake Grevelingen

Directory of Open Access Journals (Sweden)

Yvonne A. Lipsewers

2016-10-01

Full Text Available Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution at three different locations before (March and during summer hypoxia (August. The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen- and sulfur cycling in Lake Grevelingen sediments.

High Acetic Acid Production Rate Obtained by Microbial Electrosynthesis from Carbon Dioxide.

Science.gov (United States)

Jourdin, Ludovic; Grieger, Timothy; Monetti, Juliette; Flexer, Victoria; Freguia, Stefano; Lu, Yang; Chen, Jun; Romano, Mark; Wallace, Gordon G; Keller, Jurg

2015-11-17

High product specificity and production rate are regarded as key success parameters for large-scale applicability of a (bio)chemical reaction technology. Here, we report a significant performance enhancement in acetate formation from CO2, reaching comparable productivity levels as in industrial fermentation processes (volumetric production rate and product yield). A biocathode current density of -102 ± 1 A m(-2) and an acetic acid production rate of 685 ± 30 (g m(-2) day(-1)) have been achieved in this study. High recoveries of 94 ± 2% of the CO2 supplied as the sole carbon source and 100 ± 4% of electrons into the final product (acetic acid) were achieved after development of a mature biofilm, reaching an elevated product titer of up to 11 g L(-1). This high product specificity is remarkable for mixed microbial cultures, which would make the product downstream processing easier and the technology more attractive. This performance enhancement was enabled through the combination of a well-acclimatized and enriched microbial culture (very fast start-up after culture transfer), coupled with the use of a newly synthesized electrode material, EPD-3D. The throwing power of the electrophoretic deposition technique, a method suitable for large-scale production, was harnessed to form multiwalled carbon nanotube coatings onto reticulated vitreous carbon to generate a hierarchical porous structure.

Multiple paths of electron flow to current in microbial electrolysis cells fed with low and high concentrations of propionate

KAUST Repository

Rao, Hari Ananda

2016-03-03

Microbial electrolysis cells (MECs) provide a viable approach for bioenergy generation from fermentable substrates such as propionate. However, the paths of electron flow during propionate oxidation in the anode of MECs are unknown. Here, the paths of electron flow involved in propionate oxidation in the anode of two-chambered MECs were examined at low (4.5 mM) and high (36 mM) propionate concentrations. Electron mass balances and microbial community analysis revealed that multiple paths of electron flow (via acetate/H2 or acetate/formate) to current could occur simultaneously during propionate oxidation regardless of the concentration tested. Current (57–96 %) was the largest electron sink and methane (0–2.3 %) production was relatively unimportant at both concentrations based on electron balances. At a low propionate concentration, reactors supplemented with 2-bromoethanesulfonate had slightly higher coulombic efficiencies than reactors lacking this methanogenesis inhibitor. However, an opposite trend was observed at high propionate concentration, where reactors supplemented with 2-bromoethanesulfonate had a lower coulombic efficiency and there was a greater percentage of electron loss (23.5 %) to undefined sinks compared to reactors without 2-bromoethanesulfonate (11.2 %). Propionate removal efficiencies were 98 % (low propionate concentration) and 78 % (high propionate concentration). Analysis of 16S rRNA gene pyrosequencing revealed the dominance of sequences most similar to Geobacter sulfurreducens PCA and G. sulfurreducens subsp. ethanolicus. Collectively, these results provide new insights on the paths of electron flow during propionate oxidation in the anode of MECs fed with low and high propionate concentrations.

Effect of Different Carbon Substrates on Nitrate Stable Isotope Fractionation During Microbial Denitrification

DEFF Research Database (Denmark)

Wunderlich, Anja; Meckenstock, Rainer; Einsiedl, Florian

2012-01-01

-labeled water and 18O-labeled nitrite were added to the microcosm experiments to study the effect of putative backward reactions of nitrite to nitrate on the stable isotope fractionation. We found no evidence for a reverse reaction. Significant variations of the stable isotope enrichment factor ε were observed......In batch experiments, we studied the isotope fractionation in N and O of dissolved nitrate during dentrification. Denitrifying strains Thauera aromatica and “Aromatoleum aromaticum strain EbN1” were grown under strictly anaerobic conditions with acetate, benzoate, and toluene as carbon sources. 18O...... of nitrate transport across the cell wall compared to the kinetics of the intracellular nitrate reduction step of microbial denitrification....

Denitrifying capability and community dynamics of glycogen accumulating organisms during sludge granulation in an anaerobic-aerobic sequencing batch reactor

Science.gov (United States)

Bin, Zhang; Bin, Xue; Zhigang, Qiu; Zhiqiang, Chen; Junwen, Li; Taishi, Gong; Wenci, Zou; Jingfeng, Wang

2015-08-01

Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3--N could be removed or reduced, some amount of NO2--N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy.

A Combination of Stable Isotope Probing, Illumina Sequencing, and Co-occurrence Network to Investigate Thermophilic Acetate- and Lactate-Utilizing Bacteria.

Science.gov (United States)

Sun, Weimin; Krumins, Valdis; Dong, Yiran; Gao, Pin; Ma, Chunyan; Hu, Min; Li, Baoqin; Xia, Bingqing; He, Zijun; Xiong, Shangling

2018-01-01

Anaerobic digestion is a complicated microbiological process that involves a wide diversity of microorganisms. Acetate is one of the most important intermediates, and interactions between acetate-oxidizing bacteria and archaea could play an important role in the formation of methane in anoxic environments. Anaerobic digestion at thermophilic temperatures is known to increase methane production, but the effects on the microbial community are largely unknown. In the current study, stable isotope probing was used to characterize acetate- and lactate-oxidizing bacteria in thermophilic anaerobic digestion. In microcosms fed 13 C-acetate, bacteria related to members of Clostridium, Hydrogenophaga, Fervidobacterium, Spirochaeta, Limnohabitans, and Rhodococcus demonstrated elevated abundances of 13 C-DNA fractions, suggesting their activities in acetate oxidation. In the treatments fed 13 C-lactate, Anaeromyxobacter, Desulfobulbus, Syntrophus, Cystobacterineae, and Azospira were found to be the potential thermophilic lactate utilizers. PICRUSt predicted that enzymes related to nitrate and nitrite reduction would be enriched in 13 C-DNA fractions, suggesting that the acetate and lactate oxidation may be coupled with nitrate and/or nitrite reduction. Co-occurrence network analysis indicated bacterial taxa not enriched in 13 C-DNA fractions that may also play a critical role in thermophilic anaerobic digestion.

Bacillus subtilis-based direct-fed microbials augment macrophage function in broiler chickens

Science.gov (United States)

The present study was conducted to evaluate the function of Bacillus subtilis-based direct-fed microbials (DFMs) on macrophage functions, i.e., nitric oxide (NO) production and phagocytosis in broiler chickens. DFMs used in this study were eight single strains designated as Bs2084, LSSAO1, 3AP4, Bs1...

Response of Methanogenic Microbial Communities to Desiccation Stress in Flooded and Rain-Fed Paddy Soil from Thailand

Directory of Open Access Journals (Sweden)

Andreas Reim

2017-05-01

Full Text Available Rice paddies in central Thailand are flooded either by irrigation (irrigated rice or by rain (rain-fed rice. The paddy soils and their microbial communities thus experience permanent or arbitrary submergence, respectively. Since methane production depends on anaerobic conditions, we hypothesized that structure and function of the methanogenic microbial communities are different in irrigated and rain-fed paddies and react differently upon desiccation stress. We determined rates and relative proportions of hydrogenotrophic and aceticlastic methanogenesis before and after short-term drying of soil samples from replicate fields. The methanogenic pathway was determined by analyzing concentrations and δ13C of organic carbon and of CH4 and CO2 produced in the presence and absence of methyl fluoride, an inhibitor of aceticlastic methanogenesis. We also determined the abundance (qPCR of genes and transcripts of bacterial 16S rRNA, archaeal 16S rRNA and methanogenic mcrA (coding for a subunit of the methyl coenzyme M reductase and the composition of these microbial communities by T-RFLP fingerprinting and/or Illumina deep sequencing. The abundances of genes and transcripts were similar in irrigated and rain-fed paddy soil. They also did not change much upon desiccation and rewetting, except the transcripts of mcrA, which increased by more than two orders of magnitude. In parallel, rates of CH4 production also increased, in rain-fed soil more than in irrigated soil. The contribution of hydrogenotrophic methanogenesis increased in rain-fed soil and became similar to that in irrigated soil. However, the relative microbial community composition on higher taxonomic levels was similar between irrigated and rain-fed soil. On the other hand, desiccation and subsequent anaerobic reincubation resulted in systematic changes in the composition of microbial communities for both Archaea and Bacteria. It is noteworthy that differences in the community composition were

A monetary comparison of energy recovered from microbial fuel cells and microbial electrolysis cells fed winery or domestic wastewaters

Energy Technology Data Exchange (ETDEWEB)

Cusick, Roland D.; Kiely, Patrick D.; Logan, Bruce E. [Department of Civil and Environmental Engineering, H2E Center, Penn State University, University Park, PA 16802 (United States)

2010-09-15

Microbial fuel (MFCs) and electrolysis cells (MECs) can be used to recover energy directly as electricity or hydrogen from organic matter. Organic removal efficiencies and values of the different energy products were compared for MFCs and MECs fed winery or domestic wastewater. TCOD removal (%) and energy recoveries (kWh/kg-COD) were higher for MFCs than MECs with both wastewaters. At a cost of 4.51/kg-H{sub 2} for winery wastewater and 3.01/kg-H{sub 2} for domestic wastewater, the hydrogen produced using MECs cost less than the estimated merchant value of hydrogen (6/kg-H{sub 2}). 16S rRNA clone libraries indicated the predominance of Geobacter species in anodic microbial communities in MECs for both wastewaters, suggesting low current densities were the result of substrate limitations. The results of this study show that energy recovery and organic removal from wastewater are more effective with MFCs than MECs, but that hydrogen production from wastewater fed MECs can be cost effective. (author)

Acetate is a superior substrate for microbial fuel cell initiation preceding bioethanol effluent utilization

DEFF Research Database (Denmark)

Sun, Guotao; Thygesen, Anders; Meyer, Anne S.

2015-01-01

resistance. The BE mainly contained 20.5 g/L xylose, 1.8 g/Larabinose, and 2.5 g/L propionic acid. The MFCs initially fedwith acetate showed shorter initiation time (1 day), higheraverage cell voltage (634±9 mV), and higher coulombic efficiency(31.5±0.5 %) than those initially fed with ace/xyl orxylose....... However, BE-initiated MFCs only generated 162±1 mV. The acetate-initiated MFCs exhibited longer adaptation time (21 h) and lower cell voltage (645±10 mV) when the substrate was switched to xylose, whereas substrate switching to BE produced the highest voltage (656 mV), maximumpower density (362±27 mW/m2...

Diets of differentially processed wheat alter ruminal fermentation parameters and microbial populations in beef cattle.

Science.gov (United States)

Jiang, S Z; Yang, Z B; Yang, W R; Li, Z; Zhang, C Y; Liu, X M; Wan, F C

2015-11-01

The influences of differently processed wheat products on rumen fermentation, microbial populations, and serum biochemistry profiles in beef cattle were studied. Four ruminally cannulated Limousin × Luxi beef cattle (400 ± 10 kg) were used in the experiment with a 4 × 4 Latin square design. The experimental diets contained (on a DM basis) 60% corn silage as a forage source and 40% concentrate with 4 differently processed wheat products (extruded, pulverized, crushed, and rolled wheat). Concentrations of ruminal NH-N and microbial protein (MCP) in cattle fed crushed and rolled wheat were greater ( Ruminal concentrations of total VFA and acetate and the ratio of acetate to propionate decreased ( 0.05). Our findings suggest that the method of wheat processing could have a significant effect on ruminal fermentation parameters and microbial populations in beef cattle and that crushed and rolled processing is better in terms of ruminal NH-N and MCP content, acetate-to-propionate ratio, and relative abundance of rumen microorganisms.

Microbial reduction of Fe(III) and turnover of acetate in Hawaiian soils.

Science.gov (United States)

Küsel, Kirsten; Wagner, Christine; Trinkwalter, Tanja; Gössner, Anita S; Bäumler, Rupert; Drake, Harold L

2002-04-01

Soils contain anoxic microzones, and acetate is an intermediate during the turnover of soil organic carbon. Due to negligible methanogenic activities in well-drained soils, acetate accumulates under experimentally imposed short-term anoxic conditions. In contrast to forest, agricultural, and prairie soils, grassland soils from Hawaii rapidly consumed rather than formed acetate when incubated under anoxic conditions. Thus, alternative electron acceptors that might be linked to the anaerobic oxidation of soil organic carbon in Hawaiian soils were assessed. Under anoxic conditions, high amounts of Fe(II) were formed by Hawaiian soils as soon as soils were depleted of nitrate. Rates of Fe(II) formation for different soils ranged from 0.01 to 0.31 micromol (g dry weight soil)(-1) h(-1), but were not positively correlated to increasing amounts of poorly crystallized iron oxides. In general, sulfate-reducing and methanogenic activities were negligible. Supplemental acetate was rapidly oxidized to CO2 via the sequential reduction of nitrate and Fe(III) in grassland soil (obtained near Kaena State Park). Supplemental H2 stimulated the formation of Fe(II), but H2-utilizing acetogens appeared to also be involved in the consumption of H2. Approximately 270 micromol Fe(III) (g dry weight soil)(-1) was available for Fe(III)-reducing bacteria, and acetate became a stable end product when Fe(III) was depleted in long-term incubations. Most-probable-number estimates of H2- and acetate-utilizing Fe(III) reducers and of H2-utilizing acetogens were similar. These results indicate that (i) the microbial reduction of Fe(III) is an important electron-accepting process for the anaerobic oxidation of organic matter in Fe(III)-rich Hawaiian soils of volcanic origin, and (ii) acetate, formed by the combined activity of fermentative and acetogenic bacteria, is an important trophic link in anoxic microsites of these soils.

Relationships Between Denitrifier Abundance, Denitrifier Diversity and Denitrification in Gulf of Mexico Hypoxic Zone Sediments.

Science.gov (United States)

Proctor, L. M.; Childs, C.; MacAuley, S.

2002-12-01

The largest zone of anthropogenic bottom water hypoxia in the Western Hemisphere occurs seasonally in the northern Gulf of Mexico. This hypoxic zone reaches its greatest extent in the summer months and is a consequence of seasonal stratification of the water column combined with the decomposition of organic matter derived from accelerated rates of primary production. The enhanced primary production is driven by inorganic nitrogen input from the Mississippi River and these conditions would seem ideal for supporting high levels of denitrification. Yet sediment denitrification exhibited a wide range, even at the height of the seasonal hypoxia. Therefore, we compared benthic denitrifier abundances and denitrifier diversity at several stations over two seasons exhibiting extremes in denitrification to evaluate the relationship between abundances, diversity and denitrification levels. Sediment denitrification ranged from 20 to 100 umol m-2 h-1, with rates in July, 2000 approximately half that observed in July, 2001. The highest rates were generally observed at stations with bottom water DO concentrations between 1 and 3 mg l-1. Relative denitrifier abundances, using nirS and nirK as proxies for denitrifiers, suggested a direct relationship between abundances and denitrification while denitrifier diversity, measured by T-RFLPs of nirS and nirK, suggested an inverse relationship between diversity and denitrification. These results suggest that several factors are important in understanding what controls denitrification in Gulf of Mexico hypoxic zone sediments.

Denitrification and Biodiversity of Denitrifiers in a High-Mountain Mediterranean Lake

Directory of Open Access Journals (Sweden)

Antonio Castellano-Hinojosa

2017-10-01

Full Text Available Wet deposition of reactive nitrogen (Nr species is considered a main factor contributing to N inputs, of which nitrate (NO3− is usually the major component in high-mountain lakes. The microbial group of denitrifiers are largely responsible for reduction of nitrate to molecular dinitrogen (N2 in terrestrial and aquatic ecosystems, but the role of denitrification in removal of contaminant nitrates in high-mountain lakes is not well understood. We have used the oligotrophic, high-altitude La Caldera lake in the Sierra Nevada range (Spain as a model to study the role of denitrification in nitrate removal. Dissolved inorganic Nr concentration in the water column of la Caldera, mainly nitrate, decreased over the ice-free season which was not associated with growth of microbial plankton or variations in the ultraviolet radiation. Denitrification activity, estimated as nitrous oxide (N2O production, was measured in the water column and in sediments of the lake, and had maximal values in the month of August. Relative abundance of denitrifying bacteria in sediments was studied by quantitative polymerase chain reaction of the 16S rRNA and the two phylogenetically distinct clades nosZI and nosZII genes encoding nitrous oxide reductases. Diversity of denitrifiers in sediments was assessed using a culture-dependent approach and after the construction of clone libraries employing the nosZI gene as a molecular marker. In addition to genera Polymorphum, Paracoccus, Azospirillum, Pseudomonas, Hyphomicrobium, Thauera, and Methylophaga, which were present in the clone libraries, Arthrobacter, Burkholderia, and Rhizobium were also detected in culture media that were not found in the clone libraries. Analysis of biological activities involved in the C, N, P, and S cycles from sediments revealed that nitrate was not a limiting nutrient in the lake, allowed N2O production and determined denitrifiers’ community structure. All these results indicate that

Denitrification and Biodiversity of Denitrifiers in a High-Mountain Mediterranean Lake

Science.gov (United States)

Castellano-Hinojosa, Antonio; Correa-Galeote, David; Carrillo, Presentación; Bedmar, Eulogio J.; Medina-Sánchez, Juan M.

2017-01-01

Wet deposition of reactive nitrogen (Nr) species is considered a main factor contributing to N inputs, of which nitrate (NO3−) is usually the major component in high-mountain lakes. The microbial group of denitrifiers are largely responsible for reduction of nitrate to molecular dinitrogen (N2) in terrestrial and aquatic ecosystems, but the role of denitrification in removal of contaminant nitrates in high-mountain lakes is not well understood. We have used the oligotrophic, high-altitude La Caldera lake in the Sierra Nevada range (Spain) as a model to study the role of denitrification in nitrate removal. Dissolved inorganic Nr concentration in the water column of la Caldera, mainly nitrate, decreased over the ice-free season which was not associated with growth of microbial plankton or variations in the ultraviolet radiation. Denitrification activity, estimated as nitrous oxide (N2O) production, was measured in the water column and in sediments of the lake, and had maximal values in the month of August. Relative abundance of denitrifying bacteria in sediments was studied by quantitative polymerase chain reaction of the 16S rRNA and the two phylogenetically distinct clades nosZI and nosZII genes encoding nitrous oxide reductases. Diversity of denitrifiers in sediments was assessed using a culture-dependent approach and after the construction of clone libraries employing the nosZI gene as a molecular marker. In addition to genera Polymorphum, Paracoccus, Azospirillum, Pseudomonas, Hyphomicrobium, Thauera, and Methylophaga, which were present in the clone libraries, Arthrobacter, Burkholderia, and Rhizobium were also detected in culture media that were not found in the clone libraries. Analysis of biological activities involved in the C, N, P, and S cycles from sediments revealed that nitrate was not a limiting nutrient in the lake, allowed N2O production and determined denitrifiers’ community structure. All these results indicate that denitrification could be a

Microbial Diversity in KURT Groundwater and Biomineralization Characteristics

International Nuclear Information System (INIS)

Roh, Yul; Rhee, Sung Keun; Oh, Jong Min; Park, Byung Jun

2009-03-01

The Underground Research Tunnel (URT) located in Korea Atomic Energy Research Institute (KAERI), Daejeon, South Korea was recently constructed as an experimental site to study radionuclide transport, biogeochemistry, radionuclide-mineral interactions for the geological disposal of high level nuclear waste. Groundwater sampled from URT was used to examine microbial diversity and to enrich metal reducing bacteria for studying microbe-metal interactions. Genomic analysis indicated that the groundwater contained diverse microorganisms such as metal reducers, metal oxidizers, anaerobic denitrifying bacteria, and bacteria for reductive dechlorination. Metal-reducing bacteria enriched from the groundwater was used to study metal reduction and biomineralization. The metal-reducing bacteria enriched with acetate or lactate as the electron donors showed the bacteria reduced Fe(III)-citrate, Fe(III) oxyhydroxides, Mn(IV) oxide, and Cr(VI) as the electron acceptors. Preliminary study indicated that the enriched bacteria were able to use glucose, lactate, acetate, and hydrogen as electron donors while reducing Fe(III)-citrate or Fe(III) oxyhydroxide as the electron acceptor. The bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite, siderite, and rhodochrosite. The results indicated that Fe(III)- and metal-reducing communities are present in URT at the KAERI

Soil denitrifier community size changes with land use change to perennial bioenergy cropping systems

Science.gov (United States)

Thompson, Karen A.; Deen, Bill; Dunfield, Kari E.

2016-10-01

Dedicated biomass crops are required for future bioenergy production. However, the effects of large-scale land use change (LUC) from traditional annual crops, such as corn-soybean rotations to the perennial grasses (PGs) switchgrass and miscanthus, on soil microbial community functioning is largely unknown. Specifically, ecologically significant denitrifying communities, which regulate N2O production and consumption in soils, may respond differently to LUC due to differences in carbon (C) and nitrogen (N) inputs between crop types and management systems. Our objective was to quantify bacterial denitrifying gene abundances as influenced by corn-soybean crop production compared to PG biomass production. A field trial was established in 2008 at the Elora Research Station in Ontario, Canada (n  =  30), with miscanthus and switchgrass grown alongside corn-soybean rotations at different N rates (0 and 160 kg N ha-1) and biomass harvest dates within PG plots. Soil was collected on four dates from 2011 to 2012 and quantitative PCR was used to enumerate the total bacterial community (16S rRNA) and communities of bacterial denitrifiers by targeting nitrite reductase (nirS) and N2O reductase (nosZ) genes. Miscanthus produced significantly larger yields and supported larger nosZ denitrifying communities than corn-soybean rotations regardless of management, indicating large-scale LUC from corn-soybean to miscanthus may be suitable in variable Ontario climatic conditions and under varied management, while potentially mitigating soil N2O emissions. Harvesting switchgrass in the spring decreased yields in N-fertilized plots, but did not affect gene abundances. Standing miscanthus overwinter resulted in higher 16S rRNA and nirS gene copies than in fall-harvested crops. However, the size of the total (16S rRNA) and denitrifying bacterial communities changed differently over time and in response to LUC, indicating varying controls on these communities.

Immune modulation by Bacillus subtilus-based direct-fed microbials in commercial broiler chickens

Science.gov (United States)

Direct-fed microbials (DFMs), also known as probiotics, have been successfully used to improve the balance of gut microbiota. Spores of Bacillus subtilis, have been used as DFMs for food animals and humans and our previous studies showed that dietary supplementation of broiler chickens with a B. su...

Fed-batch fermentation dealing with nitrogen limitation in microbial transglutaminase production by Streptoverticillium mobaraense

NARCIS (Netherlands)

Rinzema, A; Tramper, J; de Bruin, E; Bol, J

In the later stages of a batch fermentation for microbial transglutaminase production by Streptoverticillium mobaraense the availability of a nitrogen source accessible to the microorganism becomes critical. Fed-batch fermentation is investigated with the aim of avoiding this substrate limitation.

Microbial community analysis of perchlorate-reducing cultures growing on zero-valent iron

International Nuclear Information System (INIS)

Son, Ahjeong; Schmidt, Carl J.; Shin, Hyejin; Cha, Daniel K.

2011-01-01

Anaerobic microbial mixed cultures demonstrated its ability to completely remove perchlorate in the presence of zero-valent iron. In order to understand the major microbial reaction in the iron-supported culture, community analysis comprising of microbial fatty acids and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) techniques was performed for perchlorate reducing cultures. Analysis of fatty acid methyl esters (FAMEs) and subsequent principal component analysis (PCA) showed clear distinctions not only between iron-supported perchlorate reducing culture and seed bacteria, but also among perchlorate-reducing cultures receiving different electron donors. The DGGE pattern targeting the chlorite dismutase (cld) gene showed that iron-supported perchlorate reducing culture is similar to hydrogen-fed cultures as compared to acetate-fed culture. The phylogenetic tree suggested that the dominant microbial reaction may be a combination of the autotrophic and heterotrophic reduction of perchlorate. Both molecular and chemotaxonomic experimental results support further understanding in the function of zero-valent iron as an adequate electron source for enhancing the microbial perchlorate reduction in natural and engineered systems.

Microbial community analysis of perchlorate-reducing cultures growing on zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Son, Ahjeong, E-mail: ason@auburn.edu [Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Schmidt, Carl J. [Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716 (United States); Shin, Hyejin [Department of Mathematics and Statistics, Auburn University, Auburn, AL 36849 (United States); Cha, Daniel K. [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States)

2011-01-30

Anaerobic microbial mixed cultures demonstrated its ability to completely remove perchlorate in the presence of zero-valent iron. In order to understand the major microbial reaction in the iron-supported culture, community analysis comprising of microbial fatty acids and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) techniques was performed for perchlorate reducing cultures. Analysis of fatty acid methyl esters (FAMEs) and subsequent principal component analysis (PCA) showed clear distinctions not only between iron-supported perchlorate reducing culture and seed bacteria, but also among perchlorate-reducing cultures receiving different electron donors. The DGGE pattern targeting the chlorite dismutase (cld) gene showed that iron-supported perchlorate reducing culture is similar to hydrogen-fed cultures as compared to acetate-fed culture. The phylogenetic tree suggested that the dominant microbial reaction may be a combination of the autotrophic and heterotrophic reduction of perchlorate. Both molecular and chemotaxonomic experimental results support further understanding in the function of zero-valent iron as an adequate electron source for enhancing the microbial perchlorate reduction in natural and engineered systems.

Stable acetate production in extreme-thermophilic (70°C) mixed culture fermentation by selective enrichment of hydrogenotrophic methanogens

Science.gov (United States)

Zhang, Fang; Zhang, Yan; Ding, Jing; Dai, Kun; van Loosdrecht, Mark C. M.; Zeng, Raymond J.

2014-06-01

The control of metabolite production is difficult in mixed culture fermentation. This is particularly related to hydrogen inhibition. In this work, hydrogenotrophic methanogens were selectively enriched to reduce the hydrogen partial pressure and to realize efficient acetate production in extreme-thermophilic (70°C) mixed culture fermentation. The continuous stirred tank reactor (CSTR) was stable operated during 100 days, in which acetate accounted for more than 90% of metabolites in liquid solutions. The yields of acetate, methane and biomass in CSTR were 1.5 +/- 0.06, 1.0 +/- 0.13 and 0.4 +/- 0.05 mol/mol glucose, respectively, close to the theoretical expected values. The CSTR effluent was stable and no further conversion occurred when incubated for 14 days in a batch reactor. In fed-batch experiments, acetate could be produced up to 34.4 g/L, significantly higher than observed in common hydrogen producing fermentations. Acetate also accounted for more than 90% of soluble products formed in these fed-batch fermentations. The microbial community analysis revealed hydrogenotrophic methanogens (mainly Methanothermobacter thermautotrophicus and Methanobacterium thermoaggregans) as 98% of Archaea, confirming that high temperature will select hydrogenotrophic methanogens over aceticlastic methanogens effectively. This work demonstrated a potential application to effectively produce acetate as a value chemical and methane as an energy gas together via mixed culture fermentation.

Denitrification of groundwater using a sulfur-oxidizing autotrophic denitrifying anaerobic fluidized-bed MBR: performance and bacterial community structure.

Science.gov (United States)

Zhang, Lili; Zhang, Chao; Hu, Chengzhi; Liu, Huijuan; Qu, Jiuhui

2015-03-01

This paper investigates a novel sulfur-oxidizing autotrophic denitrifying anaerobic fluidized bed membrane bioreactor (AnFB-MBR) that has the potential to overcome the limitations of conventional sulfur-oxidizing autotrophic denitrification systems. The AnFB-MBR produced consistent high-quality product water when fed by a synthetic groundwater with NO3 (-)-N ranging 25-80 mg/L and operated at hydraulic retention times of 0.5-5.0 h. A nitrate removal rate of up to 4.0 g NO3 (-)-N/Lreactord was attained by the bioreactor, which exceeded any reported removal capacity. The flux of AnFB-MBR was maintained in the range of 1.5-15 L m(-2) h(-1). Successful membrane cleaning was practiced with cleaning cycles of 35-81 days, which had no obvious effect on the AnFB-MBR performance. The (15) N-tracer analyses elucidated that nitrogen was converted into (15) N2-N and (15) N-biomass accounting for 88.1-93.1 % and 6.4-11.6 % of the total nitrogen produced, respectively. Only 0.3-0.5 % of removed nitrogen was in form of (15)N2O-N in sulfur-oxidizing autotrophic denitrification process, reducing potential risks of a significant amount of N2O emissions. The sulfur-oxidizing autotrophic denitrifying bacterial consortium was composed mainly of bacteria from Proteobacteria, Chlorobi, and Chloroflexi phyla, with genera Thiobacillus, Sulfurimonas, and Ignavibacteriales dominating the consortium. The pyrosequencing assays also suggested that the stable microbial communities corresponded to the elevated performance of the AnFB-MBR. Overall, this research described relatively high nitrate removal, acceptable flux, indicating future potential for the technology in practice.

Site-specific variability in BTEX biodegradation under denitrifying conditions

International Nuclear Information System (INIS)

Kao, C.M.; Borden, R.C.

1997-01-01

Laboratory microcosm experiments were conducted to evaluate the feasibility of benzene, toluene, ethylbenzene, m-xylene, and o-xylene (BTEX) biodegradation under denitrifying conditions. Nine different sources of inocula, including contaminated and uncontaminated soil cores from four different sites and activated sludge, were used to establish microcosms. BTEX was not degraded under denitrifying conditions in microcosms inoculated with aquifer material from Rocky Point and Traverse City. However, rapid depletion of glucose under denitrifying conditions was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing Rocky Point aquifer material. TEX degradation was observed in microcosms containing aquifer material from Fort Bragg and Sleeping Bear Dunes and sewage sludge. Benzene was recalcitrant in all microcosms tested. The degradation of o-xylene ceased after toluene, ethylbenzene, and m-xylene were depleted in the Fort Bragg and sludge microcosms, but o-xylene continued to degrade in microcosms with contaminated Sleeping Bear Dunes soil. The most probable number (MPN) of denitrifiers in these nine different inocula were measured using a microtiter technique. There was no correlation between the MPN of denitrifiers and the TEX degradation rate under denitrifying conditions. Experimental results indicate that the degradation sequence and TEX degradation rate under denitrifying conditions may differ among sites. Results also indicate that denitrification alone may not be a suitable bioremediation technology for gasoline-contaminated aquifers because of the inability of denitrifiers to degrade benzene

Microbial Diversity and Characteristics in Anaerobic Environments in KURT Groundwater

International Nuclear Information System (INIS)

Roh, Yul; Oh, Jong Min; Rhee, Sung Keun; Yong, Jong Joong

2008-03-01

The Underground Research Tunnel (URT) located in Korea Atomic Energy Research Institute (KAERI), Daejeon, South Korea was recently constructed as an experimental site to study radionuclide transport, biogeochemistry, radionuclide-mineral interactions for the geological disposal of high level nuclear waste. Groundwater sampled from URT was used to examine microbial diversity and to enrich metal reducing bacteria for studying microbe-metal interactions. Genomic analysis indicated that the groundwater contained diverse microorganisms such as metal reducers, metal oxidizers, anaerobic denitrifying bacteria, and bacteria for reductive dechlorination. Metal-reducing bacteria enriched from the groundwater was used to study metal reduction and biomineralization. The metal-reducing bacteria enriched with acetate or lactate as the electron donors showed the bacteria reduced Fe(III)-citrate, Fe(III) oxyhydroxide, Mn(IV) oxide, and Cr(VI) as the electron acceptors. Preliminary study indicated that the enriched bacteria were able to use glucose, lactate, acetate, and hydrogen as electron donors while reducing Fe(III)-citrate or Fe(III) oxyhydroxide as the electron acceptor. The bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite, siderite, and rhodochrosite. The results indicated that Fe(III)- and metal-reducing communities are present in URT at the KAERI

Microbial activity in subsurface samples before and during nitrate-enhanced bioremediation

International Nuclear Information System (INIS)

Thomas, J.M.; Gordy, V.R.; Bruce, C.L.; Ward, C.H.; Hutchins, S.R.; Sinclair, J.L.

1995-01-01

A study was conducted to determine the microbial activity at a site contaminated with JP-4 jet fuel before and during nitrate-enhanced bioremediation. Samples at three depths from six different locations were collected aseptically under anaerobic conditions before and during treatment. Cores were located in or close to the source of contamination, downgradient of the source, or outside the zone of contamination. Parameters for microbial characterization included (1) viable counts of aerobic heterotrophic, JP-4 degrading, and oligotrophic bacteria; (2) the most probable number (MPN) of aerobic and anaerobic protozoa; (3) the MPN of total denitrifiers; and (4) the MPN of denitrifiers in hydrocarbon-amended microcosms. The results indicate that the total number of denitrifiers increased by an order of magnitude during nitrate-enhanced bioremediation in most samples. The number of total heterotrophs and JP-4-degrading microorganisms growing aerobically also increased. In addition, the first anaerobic protozoa associated with hydrocarbon-contaminated subsurface materials were detected

Does reactor staging influence microbial structure and functions in biofilm systems? The case of pre-denitrifying MBBRs

DEFF Research Database (Denmark)

Polesel, Fabio; Torresi, Elena; Jensen, Marlene Mark

-stage MBBR system (S1+S2+S3), fed with pre-clarified wastewater, was operated at laboratory-scale with (i) controlled biomass exposure to organic substrate (COD); and (ii) enhanced the physical retention of biomass, thus inducing adaptation to different substrate exposure conditions. During long...... (exposed to lowest availability). These findings indicate that the exposure to tiered substrate availability influenced the capacity of utilizing a different range of carbon sources in each MBBR, thus impacting denitrification and pharmaceutical biotransformation. Preliminary analysis on the microbial...

Alignment of microbial fitness with engineered product formation: obligatory coupling between acetate production and photoautotrophic growth.

Science.gov (United States)

Du, Wei; Jongbloets, Joeri A; van Boxtel, Coco; Pineda Hernández, Hugo; Lips, David; Oliver, Brett G; Hellingwerf, Klaas J; Branco Dos Santos, Filipe

2018-01-01

Microbial bioengineering has the potential to become a key contributor to the future development of human society by providing sustainable, novel, and cost-effective production pipelines. However, the sustained productivity of genetically engineered strains is often a challenge, as spontaneous non-producing mutants tend to grow faster and take over the population. Novel strategies to prevent this issue of strain instability are urgently needed. In this study, we propose a novel strategy applicable to all microbial production systems for which a genome-scale metabolic model is available that aligns the production of native metabolites to the formation of biomass. Based on well-established constraint-based analysis techniques such as OptKnock and FVA, we developed an in silico pipeline-FRUITS-that specifically 'Finds Reactions Usable in Tapping Side-products'. It analyses a metabolic network to identify compounds produced in anabolism that are suitable to be coupled to growth by deletion of their re-utilization pathway(s), and computes their respective biomass and product formation rates. When applied to Synechocystis sp. PCC6803, a model cyanobacterium explored for sustainable bioproduction, a total of nine target metabolites were identified. We tested our approach for one of these compounds, acetate, which is used in a wide range of industrial applications. The model-guided engineered strain shows an obligatory coupling between acetate production and photoautotrophic growth as predicted. Furthermore, the stability of acetate productivity in this strain was confirmed by performing prolonged turbidostat cultivations. This work demonstrates a novel approach to stabilize the production of target compounds in cyanobacteria that culminated in the first report of a photoautotrophic growth-coupled cell factory. The method developed is generic and can easily be extended to any other modeled microbial production system.

[Identification and function test of an alkali-tolerant denitrifying bacterium].

Science.gov (United States)

Wang, Ru; Zheng, Ping; Li, Wei; Chen, Hui; Chen, Tingting; Ghulam, Abbas

2013-04-04

We obtained an alkali-tolerant denitrifying bacterium, and determined its denitrifying activity and alkali-tolerance. An alkali-tolerant denitrifying bacterial strain was obtained by isolation and purification. We identified the bacterial strain by morphological observation, physiological test and 16S rRNA analysis. We determined the denitrifying activity and alkali-tolerance by effects of initial nitrate concentration and initial pH on denitrification. An alkali-tolerant denitrifier strain R9 was isolated from the lab-scale high-rate denitrifying reactor, and it was identified as Diaphorobater nitroreducens. The strain R9 grew heterotrophically with methanol as the electron donor and nitrate as the electron acceptor. The nitrate conversion was 93.25% when strain R9 was cultivated for 288 h with initial nitrate concentration 50 mg/L and initial pH 9.0. The denitrification activity could be inhibited at high nitrate concentration with a half inhibition constant of 202.73 mg N/L. Strain R9 showed a good alkali tolerance with the nitrate removal rate at pH 11.0 remained 86% of that at pH 9.0. Strain R9 was identified as Diaphorobater nitroreducens, and it was an alkali-tolerant denitrifying bacterium with optimum pH value of 9.0.

Rumen microbial changes in cattle fed diets with or without salinomycin.

OpenAIRE

Olumeyan, D B; Nagaraja, T G; Miller, G W; Frey, R A; Boyer, J E

1986-01-01

Four rumen-fistulated steers, randomly assigned to two groups (control and salinomycin fed) were used to monitor the changes in rumen microbial populations and volatile fatty acids (VFA) concentrations associated with feeding salinomycin (0.22 mg X kg-1 X day-1). Steers were adapted to an alfalfa hay and grain (80:20) diet before supplementing the diet with salinomycin, and then the diet was changed to 50:50 and 20:80 ratios of alfalfa hay to grain at 2-week intervals. Rumen samples for total...

Synthetic Klebsiella pneumoniae-Shewanella oneidensis Consortium Enables Glycerol-Fed High-Performance Microbial Fuel Cells.

Science.gov (United States)

Li, Feng; Yin, Changji; Sun, Liming; Li, Yuanxiu; Guo, Xuewu; Song, Hao

2018-05-01

Microbial fuel cell (MFC) is an eco-friendly bio-electrochemical sys-tem that uses microorganism as biocatalyst to convert biomass into electricity. Glycerol, as a waste in the biodiesel refinery processes, is an appealing substrate for MFC. Nevertheless, glycerol cannot be utilized as carbon source by well-known exoelectrogens such as Shewanella oneidensis. Herein, to generate electricity by rapidly harnessing glycerol, the authors rationally constructed a Klebsiella pneumoniae-Shewanella oneidensis microbial consortium to efficiently harvest electricity from glyc-erol, in which K. pneumoniae converted glycerol into lactate, fed to S. oneidensis as carbon source and electron donor. To improve electricity output, the authors systematically engineered the consortium in terms of carbon flux distribution and efficiency of extracellular electron transfer (EET). To direct more carbon flux to lactate biosynthesis in K. pneumoniae, the authors eliminated the ethanol pathway by knocking out the alcohol dehydrogenase gene (adhE), and enhanced lactate biosynthesis by heterologously expressing a lactate dehydrogen-ase gene (ldhD) from Lactobacillus bulgaricus and a lactate transporter gene (lldP) from Escherichia coli. To facilitate EET between S. oneidensis and anode surfaces, a biosynthetic flavins pathway from Bacillus subtilis is introduced into S. oneidensis. The author further optimized the glycerol concentration, thus S. oneidensis could be continuously fed with lactate synthesized from K. pneumoniae at a constant rate. Our glycerol-fed MFC generated a maximum power density of 19.9 mW/m 2 , significantly higher than that of the wild-type consor-tium. This work suggested that engineering microbial consortia is an effi-cient strategy to expand the spectrum of usable carbon sources and promote electricity power production in MFCs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Incorporation in vivo of 1-14C-acetate into lipids of rats fed threonine imbalanced diet

International Nuclear Information System (INIS)

Maeda, Hideo; Sugano, Michihiro

1975-01-01

In order to investigate the mechanism of the fatty liver production in rats fed the thereonine imbalanced diet, time course of lipogenesis was followed after intraperitoneal injection of 1- 14 C-acetate into rats that had been reared on the imbalanced diet for 7 days. 1) The rate of the incorporation of 1- 14 C-acetate into hepatic triglyceride, estimated either on the base of unit weight of liver or of whole liver, in comparison with that of the control rats, did not increase by feeding the imbalanced diet under the condition where the extent of lipogenesis could be measured (30 min after the dose of the label). Also, the specific activity of triglyceride was by no means high at this point. The rate of disappearance of the radioactivity, between 60 min and 180 min after the label injection, from triglyceride was evidently slower in rats fed the imbalanced diet, thus the radioactivity of triglyceride in this animal being to some extent higher after 180 min. 2) The incorporation of radioactivity into phospholipid was not influenced by the imbalanced diet. 3) There was no difference in the incorporation of the radioactivity into kidney lipids between the control and imbalanced groups. 4) From the distribution of the radioactivity in the hepatic lipid fractions, it appeared that the relative incorporation into triglyceride tended to increase after feeding the imbalanced diet. 5) There were no demonstrable differences in the activity of plasma total lipids at any times after the injection of the label. The ratio of the label incorporation into whole plasma and liver total lipids tended to decrease in the imbalanced rat after 180 min. These results suggested that, although alternative explanations are possible, the decreased turnover in hepatic triglyceride, rather than the increased hepatic lipogenesis, would largely be responsible for the production of fatty liver in rats fed the threonine imbalanced diet. (auth.)

Characterization of bacterial consortia capable of degrading 4-chlorobenzoate and 4-bromobenzoate under denitrifying conditions.

Science.gov (United States)

Song, Bongkeun; Kerkhof, Lee J; Häggblom, Max M

2002-08-06

4-Chlorobenzoate and 4-bromobenzoate were readily degraded in denitrifying enrichment cultures established with river sediment, estuarine sediment or agricultural soil as inoculum. Stable denitrifying consortia were obtained and maintained by serial dilution and repeated feeding of substrates. Microbial community analyses were performed to characterize the 4-chlorobenzoate and 4-bromobenzoate degrading consortia with terminal restriction fragment length polymorphism (T-RFLP) and cloning of 16S rRNA genes from the cultures. Interestingly, two major terminal restriction fragments (T-RFs) in the 4-chlorobenzoate degrading consortia and one T-RF in the 4-bromobenzoate utilizing consortium were observed from T-RFLP analysis regardless of their geographical and ecological origins. The two T-RFs (clones 4CB1 and 4CB2) in 4-chlorobenzoate degrading consortia were identified as members of the beta-subunit of the Proteobacteria on the basis of 16S rRNA sequencing analysis. Phylogenetic analysis of 16S rRNA genes showed that clone 4CB1 was closely related to Thauera aromatica while clone 4CB2 was distantly related to the genera Limnobacter and Ralstonia. The 4-bromobenzoate utilizing consortium mainly consisted of one T-RF, which was identical to clone 4CB2 in spite of different enrichment substrate. This suggests that degradation of 4-chlorobenzoate and 4-bromobenzoate under denitrifying conditions was mediated by bacteria belonging to the beta-subunit of the Proteobacteria.

Impact of acclimation methods on microbial communities and performance of anaerobic fluidized bed membrane bioreactors

KAUST Repository

Labarge, Nicole

2016-10-17

An anaerobic fluidized bed membrane bioreactor (AFMBR) is a new and effective method for energy-efficient treatment of low strength wastewater, but the factors that affect performance are not well known. Different inocula and acclimation methods of the granular activated carbon (GAC) used in the reactor were examined here to determine their impact on chemical oxygen demand (COD) removal and microbial community composition of domestic wastewater-fed AFMBRs. AFMBRs inoculated with anaerobic digester sludge (D) or domestic wastewater (W) and fed domestic wastewater, or inoculated with a microbiologically diverse anaerobic bog sediment and acclimated using methanol (M), all produced the same COD removal of 63 ± 12% using a diluted wastewater feed (100 ± 21 mg L−1 COD). However, an AFMBR with GAC inoculated with anaerobic digester sludge and acclimated using acetate (A) showed significantly increased wastewater COD removal to 84 ± 6%. In addition, feeding the AFMBR with the M-acclimated GAC with an acetate medium for one week subsequently increased COD removal to 70 ± 6%. Microbial communities enriched on the GAC included Geobacter, sulfur-reducing bacteria, Syntrophaceae, and Chlorobiaceae, with reactor A having the highest relative abundance of Geobacter. These results showed that acetate was the most useful substrate for acclimation of GAC communities, and GAC harbors unique communities relative to those in the AFMBR influent and recirculated solution.

Effects of Selected Root Exudate Components on Nitrogen Removal and Development of Denitrifying Bacteria in Constructed Wetlands

Directory of Open Access Journals (Sweden)

Hailu Wu

2017-06-01

Full Text Available Root exudates, particularly low molecular weight carbon (LMWC substrates, are major drivers of bacterial diversity and activity in the rhizosphere environment. However, it is not well understood how specific LMWC compounds—such as organic acids, soluble sugars, and amino acids—influence the community structures of denitrifying bacteria or if there are specific functions of LMWC substrates that preferentially respond to nitrogen (N removal in constructed wetlands (CWs. To address these knowledge gaps, we added mixtures of artificial exudates to CW microcosms containing N pollutant. N removal efficiency was observed over a 48-h experimental period, and at the end of the experiment, DNA was extracted from microbial samples for assessment of the bacterial community. The removal efficiencies of TN for the exudates treatments were higher than for control groups by 47.1–58.67%. Organic acid and soluble sugar treatments increased N removal, while amino acids were negative to N removal. The microbial community was changed when artificial exudates were added, but there were no significant relationships between LMWC compounds and bacterial community composition. These results indicate that although the responses of community structures of denitrifying bacteria to LMWC additions are still uncertain, there is evidence for N removal in response to exudate additions across LMWC types.

Coproduction of acetic acid and electricity by application of microbial fuel cell technology to vinegar fermentation.

Science.gov (United States)

Tanino, Takanori; Nara, Youhei; Tsujiguchi, Takuya; Ohshima, Takayuki

2013-08-01

The coproduction of a useful material and electricity via a novel application of microbial fuel cell (MFC) technology to oxidative fermentation was investigated. We focused on vinegar production, i.e., acetic acid fermentation, as an initial and model useful material that can be produced by oxidative fermentation in combination with MFC technology. The coproduction of acetic acid and electricity by applying MFC technology was successfully demonstrated by the simultaneous progress of acetic acid fermentation and electricity generation through a series of repeated batch fermentations. Although the production rate of acetic acid was very small, it increased with the number of repeated batch fermentations that were conducted. We obtained nearly identical (73.1%) or larger (89.9%) acetic acid yields than that typically achieved by aerated fermentation (75.8%). The open-cycle voltages measured before and after fermentation increased with the total fermentation time and reached a maximum value of 0.521 V prior to the third batch fermentation. The maximum current and power densities measured in this study (19.1 μA/cm² and 2.47 μW/cm², respectively) were obtained after the second batch fermentation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Soluble arabinoxylan enhances large intestinal microbial health biomarkers in pigs fed a red meat-containing diet.

Science.gov (United States)

Williams, Barbara A; Zhang, Dagong; Lisle, Allan T; Mikkelsen, Deirdre; McSweeney, Christopher S; Kang, Seungha; Bryden, Wayne L; Gidley, Michael J

2016-04-01

The aim of this study was to investigate how moderately increased dietary red meat combined with a soluble fiber (wheat arabinoxylan [AX]) alters the large intestinal microbiota in terms of fermentative end products and microbial community profiles in pigs. Four groups of 10 pigs were fed Western-type diets containing two amounts of red meat, with or without a solubilized wheat AX-rich fraction for 4 wk. After euthanasia, fermentative end products (short-chain fatty acids, ammonia) of digesta from four sections of large intestine were measured. Di-amino-pimelic acid was a measure of total microbial biomass, and bacterial profiles were determined using a phylogenetic microarray. A factorial model determined effects of AX and meat content. Arabinoxylan was highly fermentable in the cecum, as indicated by increased concentrations of short-chain fatty acids (particularly propionate). Protein fermentation end products were decreased, as indicated by the reduced ammonia and branched-chain ratio although this effect was less prominent distally. Microbial profiles in the distal large intestine differed in the presence of AX (including promotion of Faecalibacterium prausnitzii), consistent with an increase in carbohydrate versus protein fermentation. Increased di-amino-pimelic acid (P < 0.0001) suggested increased microbial biomass for animals fed AX. Solubilized wheat AX has the potential to counteract the effects of dietary red meat by reducing protein fermentation and its resultant toxic end products such as ammonia, as well as leading to a positive shift in fermentation end products and microbial profiles in the large intestine. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Microbial Community Structure and Functions in Ethanol-Fed Sulfate Removal Bioreactors for Treatment of Mine Water

Directory of Open Access Journals (Sweden)

Malin Bomberg

2017-09-01

Full Text Available Sulfate-rich mine water must be treated before it is released into natural water bodies. We tested ethanol as substrate in bioreactors designed for biological sulfate removal from mine water containing up to 9 g L−1 sulfate, using granular sludge from an industrial waste water treatment plant as inoculum. The pH, redox potential, and sulfate and sulfide concentrations were measured twice a week over a maximum of 171 days. The microbial communities in the bioreactors were characterized by qPCR and high throughput amplicon sequencing. The pH in the bioreactors fluctuated between 5.0 and 7.7 with the highest amount of up to 50% sulfate removed measured around pH 6. Dissimilatory sulfate reducing bacteria (SRB constituted only between 1% and 15% of the bacterial communities. Predicted bacterial metagenomes indicated a high prevalence of assimilatory sulfate reduction proceeding to formation of l-cystein and acetate, assimilatory and dissimilatory nitrate reduction, denitrification, and oxidation of ethanol to acetaldehyde with further conversion to ethanolamine, but not to acetate. Despite efforts to maintain optimal conditions for biological sulfate reduction in the bioreactors, only a small part of the microorganisms were SRB. The microbial communities were highly diverse, containing bacteria, archaea, and fungi, all of which affected the overall microbial processes in the bioreactors. While it is important to monitor specific physicochemical parameters in bioreactors, molecular assessment of the microbial communities may serve as a tool to identify biological factors affecting bioreactor functions and to optimize physicochemical attributes for ideal bioreactor performance.

Methane production from formate, acetate and H2/CO2; focusing on kinetics and microbial characterization

DEFF Research Database (Denmark)

Pan, Xiaofang; Angelidaki, Irini; Alvarado-Morales, Merlin

2016-01-01

For evaluating the methanogenesis from typical methanogenic precursors (formate, acetate and H-2/CO2), CH4 production kinetics were investigated at 37 +/- 1 degrees C in batch anaerobic digestion tests and stimulated by modified Gompertz model. The results showed that maximum methanation rate from...... formate, acetate and H-2/CO2 were 19.58 +/- 0.49, 42.65 +/- 1.17 and 314.64 +/- 3.58 N mL/gVS/d in digested manure system and 6.53 +/- 0.31, 132.04 +/- 3.96 and 640.16 +/- 19.92 N mL/gVS/d in sewage sludge system during second generation incubation. Meanwhile the model could not fit well in granular...... sludge system, while the rate of formate methanation was faster than from H-2/CO2 and acetate. Considering both the kinetic results and microbial assay we could conclude that H-2/CO2 methanation was the fastest methanogenic step in digested manure and sewage sludge system with Methanomicrobiales...

Microbial ecology of denitrification in biological wastewater treatment.

Science.gov (United States)

Lu, Huijie; Chandran, Kartik; Stensel, David

2014-11-01

Globally, denitrification is commonly employed in biological nitrogen removal processes to enhance water quality. However, substantial knowledge gaps remain concerning the overall community structure, population dynamics and metabolism of different organic carbon sources. This systematic review provides a summary of current findings pertaining to the microbial ecology of denitrification in biological wastewater treatment processes. DNA fingerprinting-based analysis has revealed a high level of microbial diversity in denitrification reactors and highlighted the impacts of carbon sources in determining overall denitrifying community composition. Stable isotope probing, fluorescence in situ hybridization, microarrays and meta-omics further link community structure with function by identifying the functional populations and their gene regulatory patterns at the transcriptional and translational levels. This review stresses the need to integrate microbial ecology information into conventional denitrification design and operation at full-scale. Some emerging questions, from physiological mechanisms to practical solutions, for example, eliminating nitrous oxide emissions and supplementing more sustainable carbon sources than methanol, are also discussed. A combination of high-throughput approaches is next in line for thorough assessment of wastewater denitrifying community structure and function. Though denitrification is used as an example here, this synergy between microbial ecology and process engineering is applicable to other biological wastewater treatment processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Abundance, composition and activity of ammonia oxidizer and denitrifier communities in metal polluted rice paddies from South China.

Directory of Open Access Journals (Sweden)

Yuan Liu

Full Text Available While microbial nitrogen transformations in soils had been known to be affected by heavy metal pollution, changes in abundance and community structure of the mediating microbial populations had been not yet well characterized in polluted rice soils. Here, by using the prevailing molecular fingerprinting and enzyme activity assays and comparisons to adjacent non-polluted soils, we examined changes in the abundance and activity of ammonia oxidizing and denitrifying communities of rice paddies in two sites with different metal accumulation situation under long-term pollution from metal mining and smelter activities. Potential nitrifying activity was significantly reduced in polluted paddies in both sites while potential denitrifying activity reduced only in the soils with high Cu accumulation up to 1300 mg kg-1. Copy numbers of amoA (AOA and AOB genes were lower in both polluted paddies, following the trend with the enzyme assays, whereas that of nirK was not significantly affected. Analysis of the DGGE profiles revealed a shift in the community structure of AOA, and to a lesser extent, differences in the community structure of AOB and denitrifier between soils from the two sites with different pollution intensity and metal composition. All of the retrieved AOB sequences belonged to the genus Nitrosospira, among which species Cluster 4 appeared more sensitive to metal pollution. In contrast, nirK genes were widely distributed among different bacterial genera that were represented differentially between the polluted and unpolluted paddies. This could suggest either a possible non-specific target of the primers conventionally used in soil study or complex interactions between soil properties and metal contents on the observed community and activity changes, and thus on the N transformation in the polluted rice soils.

Community size and composition of ammonia oxidizers and denitrifiers in an alluvial intertidal wetland ecosystem

Directory of Open Access Journals (Sweden)

Ziye eHu

2014-07-01

Full Text Available Global nitrogen cycling is mainly mediated by the activity of microorganisms. Nitrogen cycle processes are mediated by functional groups of microorganisms that are affected by constantly changing environmental conditions and substrate availability. In this study, we investigated the temporal and spatial patterns of nitrifier and denitrifier communities in an intertidal wetland. Soil samples were collected over four distinct seasons from three locations with different vegetative cover. Multiple environmental factors and process rates were measured and analyzed together with the community size and composition profiles. We observed that the community size and composition of the nitrifiers and denitrifiers are affected significantly by seasonal factors, while vegetative cover affected the community composition. The seasonal impacts on the community size of ammonia oxidizing archaea (AOA are much higher than that of ammonia oxidizing bacteria (AOB. The seasonal change was a more important indicator for AOA community composition patterns, while vegetation was more important for the AOB community patterns. The microbial process rates were correlated with both the community size and composition.

COD removal characteristics in air-cathode microbial fuel cells

KAUST Repository

Zhang, Xiaoyuan

2015-01-01

© 2014 Elsevier Ltd. Exoelectrogenic microorganisms in microbial fuel cells (MFCs) compete with other microorganisms for substrate. In order to understand how this affects removal rates, current generation, and coulombic efficiencies (CEs), substrate removal rates were compared in MFCs fed a single, readily biodegradable compound (acetate) or domestic wastewater (WW). Removal rates based on initial test conditions fit first-order kinetics, but rate constants varied with circuit resistance. With filtered WW (100Ω), the rate constant was 0.18h- 1, which was higher than acetate or filtered WW with an open circuit (0.10h- 1), but CEs were much lower (15-24%) than acetate. With raw WW (100Ω), COD removal proceeded in two stages: a fast removal stage with high current production, followed by a slower removal with little current. While using MFCs increased COD removal rate due to current generation, secondary processes will be needed to reduce COD to levels suitable for discharge.

Novel Large Sulfur Bacteria in the Metagenomes of Groundwater-Fed Chemosynthetic Microbial Mats in the Lake Huron Basin

OpenAIRE

Allison M. Sharrar; Beverly E. Flood; Jake V. Bailey; Daniel S. Jones; Daniel S. Jones; Bopaiah A. Biddanda; Steven A. Ruberg; Daniel N. Marcus; Gregory J. Dick

2017-01-01

Little is known about large sulfur bacteria (LSB) that inhabit sulfidic groundwater seeps in large lakes. To examine how geochemically relevant microbial metabolisms are partitioned among community members, we conducted metagenomic analysis of a chemosynthetic microbial mat in the Isolated Sinkhole, which is in a deep, aphotic environment of Lake Huron. For comparison, we also analyzed a white mat in an artesian fountain that is fed by groundwater similar to Isolated Sinkhole, but that sits i...

Growth and hematology of juvenile pacu Piaractus mesopotamicus (Holmberg 1887 fed with increasing levels of vitamin E (DL-α-tocopheryl acetate

Directory of Open Access Journals (Sweden)

RICARDO Y. SADO

2013-03-01

Full Text Available Intensive fish production systems are characterized by 100% artificial feeding, so any dietary imbalances or deficiencies may lead to diseases outbreaks and economic losses. This study was set out to determine the effects of increasing levels of dietary vitamin E on growth and hematology of juvenile pacu. Fishes were fed for 90 days, twice a day until apparent satiation with semi-purified diets containing 0.0; 25; 50; 150; 300 or 600 mg.kg−1 diet DL-α-tocopheryl acetate in a completely randomized design trial (n=4; biometrical and hematological data were collected and analyzed. Fishes fed with vit E diet (150 mg.kg−1 showed higher (p<0.05 weight gain and specific growth. Hematocrit, erythroblast number and total plasma protein were increased (p<0.05 in fishes fed diet with no vit E diet. Vitamin E supplementation in artificial diets for pacu is essential for growth and maintenance of normal erythropoiesis.

Microbial electrosynthetic cells

Energy Technology Data Exchange (ETDEWEB)

May, Harold D.; Marshall, Christopher W.; Labelle, Edward V.

2018-01-30

Methods are provided for microbial electrosynthesis of H.sub.2 and organic compounds such as methane and acetate. Method of producing mature electrosynthetic microbial populations by continuous culture is also provided. Microbial populations produced in accordance with the embodiments as shown to efficiently synthesize H.sub.2, methane and acetate in the presence of CO.sub.2 and a voltage potential. The production of biodegradable and renewable plastics from electricity and carbon dioxide is also disclosed.

Denitrifying bacteria from the terrestrial subsurface exposed to mixed waste contamination

International Nuclear Information System (INIS)

Green, Stefan; Prakash, Om; Gihring, Thomas; Akob, Denise M.; Jasrotia, Puja; Jardine, Philip M.; Watson, David B.; Brown, Steven David; Palumbo, Anthony Vito; Kostka, Joel

2010-01-01

In terrestrial subsurface environments where nitrate is a critical groundwater contaminant, few cultivated representatives are available with which to verify the metabolism of organisms that catalyze denitrification. In this study, five species of denitrifying bacteria from three phyla were isolated from subsurface sediments exposed to metal radionuclide and nitrate contamination as part of the U.S. Department of Energy's Oak Ridge Integrated Field Research Challenge (OR-IFRC). Isolates belonged to the genera Afipia and Hyphomicrobium (Alphaproteobacteria), Rhodanobacter (Gammaproteobacteria), Intrasporangium (Actinobacteria) and Bacillus (Firmicutes). Isolates from the phylum Proteobacteria were confirmed as complete denitrifiers, whereas the Gram-positive isolates reduced nitrate to nitrous oxide. Ribosomal RNA gene analyses reveal that bacteria from the genus Rhodanobacter comprise a diverse population of circumneutral to moderately acidophilic denitrifiers at the ORIFRC site, with a high relative abundance in areas of the acidic source zone. Rhodanobacter species do not contain a periplasmic nitrite reductase and have not been previously detected in functional gene surveys of denitrifying bacteria at the OR-IFRC site. Sequences of nitrite and nitrous oxide reductase genes were recovered from the isolates and from the terrestrial subsurface by designing primer sets mined from genomic and metagenomic data and from draft genomes of two of the isolates. We demonstrate that a combination of cultivation, genomic and metagenomic data are essential to the in situ characterization of denitrifiers and that current PCR-based approaches are not suitable for deep coverage of denitrifying microorganisms. Our results indicate that the diversity of denitrifiers is significantly underestimated in the terrestrial subsurface.

[Formation of microbial populations on the surface of protective coatings].

Science.gov (United States)

Kopteva, Zh P; Zanina, V V; Piliashenko-Novokhatnyĭ, A I; Kopteva, A E; Kozlova, I A

2001-01-01

Formation of microbial cenosis on the surface of polyethylene-, polyurethane- and oil-bitumen-based protective coatings was studied in dynamics during 1, 3, 7, 14 and 21 days. It has been shown that the biofilm was formed on the protective materials during 14 days and consisted of ammonifying, denitrifying, hydrocarbon-oxidizing and sulphate-reducing bacteria referred to Pseudomonas, Arthrobacter, Bacillus and Kesulfovibrio genera. The bacteria which form the biofilm on coatings possess high denitrifying and sulphate-reducing activities. Corrosion inhibitors-biocydes, introduced in composition of oil-bitumen coatings suppressed growth and metabolic activity of corrosion-active bacteria.

Stability of U(VI) and Tc(VII) Reducing Microbial Communities to Environmental Perturbation: Development and Testing of a Thermodynamic Network Model

International Nuclear Information System (INIS)

McKinley, James P.; Istok, Jonathan

2005-01-01

Previously published research from in situ field experiments at the NABIR Field Research Center have shown that cooperative metabolism of denitrifiers and Fe(III)/sulfate reducers is essential for creating subsurface conditions favorable for U(VI) and Tc(VII) bioreduction (Istok et al., 2004). The overall goal of this project is to develop and test a thermodynamic network model for predicting the effects of substrate additions and environmental perturbations on the composition and functional stability of subsurface microbial communities. The overall scientific hypothesis is that a thermodynamic analysis of the energy-yielding reactions performed by broadly defined groups of microorganisms can be used to make quantitative and testable predictions of the change in microbial community composition that will occur when a substrate is added to the subsurface or when environmental conditions change. An interactive computer program was developed to calculate the overall growth equation and free energy yield for microorganisms that grow by coupling selected combinations of electron acceptor and electron donor half-reactions. Each group performs a specific function (e.g. oxidation of acetate coupled to reduction of nitrate); collectively the groups provide a theoretical description of the entire natural microbial community. The microbial growth data are combined with an existing thermodynamic data base for associated geochemical reactions and used to simulate the coupled microbial-geochemical response of a complex natural system to substrate addition or any other environmental perturbations

Microbial phytase addition resulted in a greater increase in phosphorus digestibility in dry-fed compared with liquid-fed non-heat-treated wheat-barley-maize diets for pigs

DEFF Research Database (Denmark)

Blaabjerg, Karoline; Thomassen, Anne-Marie; Poulsen, Hanne Damgaard

2015-01-01

The objective was to evaluate the effect of microbial phytase (1250 FTU/kg diet with 88% dry matter (DM)) on apparent total tract digestibility (ATTD) of phosphorus (P) in pigs fed a dry or soaked diet. Twenty-four pigs (65±3 kg) from six litters were used. Pigs were housed in metabolism crates a...

Direct-fed microbials in broiler chickens challenged with Eimeria maxima or raised on Clostridium spp.-contaminated used litter

Science.gov (United States)

Dietary direct-fed microbials (DFMs) influence the composition of gut microbiota and enhance gut health in broiler chickens. Increasing scientific data have been gathered to show that gut microbiota plays an important role in the development of the immune system and the maintenance of homeostasis wi...

Characterization of mixed-culture biofilms established in microbial fuel cells

International Nuclear Information System (INIS)

Yang, Suling; Du, Fangzhou; Liu, Hong

2012-01-01

For the successful operation of a microbial fuel cell, it is important to characterize the biofilm on the anode. The behavior of MFCs during initial biofilm growth and characterization of anodic biofilm were studied using two-chamber MFCs with activated sludge as inoculum. After three times' replacement of the anodic growth medium, the biofilms were well developed, and a maximum closed circuit potential of 0.41 V and 0.37 V (1000 Ω resistor) was achieved using acetate and glucose, respectively. Electron microscopy revealed that there were rod-shaped cells 0.2–0.3 μm wide by 1.5–2.5 μm long in the anode biofilm in the acetate-fed MFC, and these cells were mainly arranged by monolayer. The biofilm in the glucose-fed MFC was made of cocci-shaped cells in chains and a thick matrix. Both using acetate and glucose, the anodic bacterial communities were different than those of the activated sludge. Cyclic voltammograms suggested that extracellular electron transfer in these MFCs was accomplished mainly by the biofilms on the anode and not by bacteria-produced mediators. -- Highlights: ► The mixed-culture biofilms established in MFCs were characterized. ► The possible electron transfer mechanism was presented. ► In these MFCs the anodic area should be much larger.

A novel process-based model of microbial growth: self-inhibition in Saccharomyces cerevisiae aerobic fed-batch cultures.

Science.gov (United States)

Mazzoleni, Stefano; Landi, Carmine; Cartenì, Fabrizio; de Alteriis, Elisabetta; Giannino, Francesco; Paciello, Lucia; Parascandola, Palma

2015-07-30

Microbial population dynamics in bioreactors depend on both nutrients availability and changes in the growth environment. Research is still ongoing on the optimization of bioreactor yields focusing on the increase of the maximum achievable cell density. A new process-based model is proposed to describe the aerobic growth of Saccharomyces cerevisiae cultured on glucose as carbon and energy source. The model considers the main metabolic routes of glucose assimilation (fermentation to ethanol and respiration) and the occurrence of inhibition due to the accumulation of both ethanol and other self-produced toxic compounds in the medium. Model simulations reproduced data from classic and new experiments of yeast growth in batch and fed-batch cultures. Model and experimental results showed that the growth decline observed in prolonged fed-batch cultures had to be ascribed to self-produced inhibitory compounds other than ethanol. The presented results clarify the dynamics of microbial growth under different feeding conditions and highlight the relevance of the negative feedback by self-produced inhibitory compounds on the maximum cell densities achieved in a bioreactor.

Effects of a specific blend of essential oils on apparent nutrient digestion, rumen fermentation and rumen microbial populations in sheep fed a 50:50 alfalfa hay:concentrate diet

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N. Khateri

2017-03-01

Full Text Available Objective An experiment was conducted to investigate the effects of a specific mixture of essential oils (MEO, containing thyme, clove and cinnamon EO, on rumen microbial fermentation, nutrient apparent digestibility and blood metabolites in fistulated sheep. Methods Six sheep fitted with ruminal fistulas were used in a repeated measurement design with two 24-d periods to investigate the effect of adding MEO at 0 (control, 0.8, and 1.6 mL/d on apparent nutrient digestibility, rumen fermentation characteristics, rumen microbial population and blood chemical metabolites. Animals were fed with a 50:50 alfalfa hay:concentrate diet. Results Ruminal pH, total volatile fatty acids (VFA concentration, molar proportion of individual VFA, acetate: propionate ratio and methane production were not affected with MEO. Relative to the control, Small peptides plus amino acid nitrogen and large peptides nitrogen concentration in rumen fluid were not affected with MEO supplementation; while, rumen fluid ammonia nitrogen concentration at 0 and 6 h after morning feeding in sheep fed with 1.6 mL/d of MEO was lower (p<0.05 compared to the control and 0.8 mL/d of MEO. At 0 h after morning feeding, ammonia nitrogen concentration was higher (p<0.05 in sheep fed 0.8 mL/d of MEO relative to 1.6 mL/d and control diet. Ruminal protozoa and hyper ammonia producing (HAP bacteria counts were not affected by addition of MEO in the diet. Relative to the control, no changes were observed in the red and white blood cells, hemoglobin, hematocrit, glucose, beta-hydroxybutyric acid, cholesterol, total protein, albumin, blood urea nitrogen and aspartate aminotransferase and alanine aminotransferase concentration. Apparent total tract digestibility of dry matter, crude proten, organic matter, and neutral detergent fiber were not influenced by MEO supplementation. Conclusion The results of the present study suggested that supplementation of MEO may have limited effects on apparent

Influence of the fuel and dosage on the performance of double-compartment microbial fuel cells.

Science.gov (United States)

Asensio, Y; Fernandez-Marchante, C M; Lobato, J; Cañizares, P; Rodrigo, M A

2016-08-01

This manuscript focuses on the evaluation of the use of different types and dosages of fuels in the performance of double-compartment microbial fuel cell equipped with carbon felt electrodes and cationic membrane. Five types of fuels (ethanol, glycerol, acetate, propionate and fructose) have been tested for the same organic load (5,000 mg L(-1) measured as COD) and for one of them (acetate), the range of dosages between 500 and 20,000 mg L(-1) of COD was also studied. Results demonstrate that production of electricity depends strongly on the fuel used. Carboxylic acids are much more efficient than alcohols or fructose for the same organic load and within the range 500-5,000 mg L(-1) of acetate the production of electricity increases linearly with the amount of acetate fed but over these concentrations a change in the population composition may explain a worse performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biosynthetic studies on linalool and linalyl acetate in Ocimum canum Sims and Mentha citrate Ehrh

Energy Technology Data Exchange (ETDEWEB)

Rao, P G; Zutshi, U; Pushpangadan, P; Sobti, S N; Atal, C K [Regional Research Lab., Jammu (India)

1979-05-01

Labelled valine, leucine, acetate and glucose were fed to O. Canum and M. citrata to study the biosynthesis of linalool and linalyl acetate. The precursors were fed to intact plants as well as to fresh stem cuttings for different periods of time. Valine was found to be the best precursor for the biosynthesis of linalool and lanalyl acetate in both the experimental plants. Maximum incorporation of valine was, however, observed when it was fed alongwith non-radioactive glucose. It is suggested that valine is possibly involved in the synthesis of dimethyl allyl pyrophosphate through nonmevalonoid pathway. The labelled precursors L-U-/sup 14/C-valine, U-/sup 14/C-glucose, /sup 14/U-C-acetate and DL-1-/sup 14/C-valine were used in the study.

The performance of a thermophilic microbial fuel cell fed with synthesis gas.

Science.gov (United States)

Hussain, A; Mehta, P; Raghavan, V; Wang, H; Guiot, S R; Tartakovsky, B

2012-08-10

This study demonstrated electricity generation in a thermophilic microbial fuel cell (MFC) operated on synthesis gas (syngas) as the sole electron donor. At 50°C, a volumetric power output of 30-35 mWL(R)(-1) and a syngas conversion efficiency of 87-98% was achieved. The observed pathway of syngas conversion to electricity primarily consisted of a two-step process, where the carbon monoxide and hydrogen were first converted to acetate, which was then consumed by the anodophilic bacteria to produce electricity. A denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rDNA revealed the presence of Geobacter species, Acetobacter, methanogens and several uncultured bacteria and archaea in the anodic chamber. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

Nitrogen balance, microbial protein synthesis and blood metabolites in fattening of male Bali cattle fed ration with different protein levels in smallholder farms

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P. K. Tahuk

2018-03-01

Full Text Available Research was aimed to determine nitrogen balance, microbial protein synthesis, and blood metabolites of male Bali cattle fattening fed ration with different protein level in smallholder farms North Central Timor, Province of East Timor Tenggara, Indonesia. The cattle used were 18 heads aged 2 to 2.5 years with initial body weight of 229.86±12.46 kg. The cattle were randomly divided into three treatment groups. The T0 group was given feed the same as traditional fattening cattle practices by farmers,T1 group fed ration containing 12% crude protein (CP and 72% total digestible nutrients (TDN, andT2 group fedration containing 15% CP and 72%TDN. Cattle were fed individually for 90 days and drinkingwater ad libitum. The data were analyzedby analysis of variance.Results of research indicated the nitrogen balance, and blood urea nitrogen between T1 and T2 were relatively similar, but those were higher (P<0.05 than T0 . In contrast, microbial proteins synthesis, and blood glucose at 0, 4, and 6 hours before and after feeding were relatively similar between the groups. Blood glucose of T2 at 2 hours after intake were higher (P <0.05 than T0, but was not different with T1 . It can be concluded, that the fattening maleBali cattle fed ration containing 12% CP and 72% TDNimprovedthe nitrogen balance and blood metabolites, butit was no positive effect on the microbial proteins and N synthesis.

Modeling of Cr(VI) Bioreduction Under Fermentative and Denitrifying Conditions

Science.gov (United States)

Molins, S.; Steefel, C.; Yang, L.; Beller, H. R.

2011-12-01

The mechanisms of bioreductive immobilization of Cr(VI) were investigated by reactive transport modeling of a set of flow-through column experiments performed using natural Hanford 100H aquifer sediment. The columns were continuously eluted with 5 μM Cr(VI), 5 mM lactate as the electron donor, and selected electron acceptors (tested individually). Here we focus on the two separate experimental conditions that showed the most removal of Cr(VI) from solution: fermentation and denitrification. In each case, a network of enzymatic and abiotic reaction pathways was considered to interpret the rate of chromate reduction. The model included biomass growth and decay, and thermodynamic limitations on reaction rates, and was constrained by effluent concentrations measured by IC and ICP-MS and additional information from bacterial isolates from column effluent. Under denitrifying conditions, Cr(VI) reduction was modeled as co-metabolic with nitrate reduction based on experimental observations and previous studies on a denitrifying bacterium derived from the Hanford 100H aquifer. The reactive transport model results supported this interpretation of the reaction mechanism and were used to quantify the efficiency of the process. The models results also suggest that biomass growth likely relied on a nitrogen source other than ammonium (e.g. nitrate). Under fermentative conditions and based on cell suspension studies performed on a bacterial isolate from the columns, the model assumes that Cr(VI) reduction is carried out directly by fermentative bacteria that convert lactate into acetate and propionate. The evolution to complete lactate fermentation and Cr(VI) reduction took place over a week's time and simulations were used to determine an estimate for a lower limit of the rate of chromate reduction by calibration with the flow-through column experimental results. In spite of sulfate being added to these columns, sulfate reduction proceeded at a slow rate and was not well

Denitrifying sulfide removal process on high-salinity wastewaters in the presence of Halomonas sp.

Science.gov (United States)

Liu, Chunshuang; Zhao, Dongfeng; Ma, Wenjuan; Guo, Yadong; Wang, Aijie; Wang, Qilin; Lee, Duu-Jong

2016-02-01

Biological conversion of sulfide, acetate, and nitrate to, respectively, elemental sulfur (S(0)), carbon dioxide, and nitrogen-containing gas (such as N2) at NaCl concentration of 35-70 g/L was achieved in an expanded granular sludge bed (EGSB) reactor. A C/N ratio of 1:1 was noted to achieve high sulfide removal and S(0) conversion rate at high salinity. The extracellular polymeric substance (EPS) quantities were increased with NaCl concentration, being 11.4-mg/g volatile-suspended solids at 70 mg/L NaCl. The denitrifying sulfide removal (DSR) consortium incorporated Thauera sp. and Halomonas sp. as the heterotrophs and Azoarcus sp. being the autotrophs at high salinity condition. Halomonas sp. correlates with the enhanced DSR performance at high salinity.

Effects of Bacillus subtilis-based direct-fed microbials on growth performance, immune characteristics and resistance against experimental coccidiosis in broiler chickens

Science.gov (United States)

The present experiment was conducted to study the effects of dietary Bacillus-based direct-fed microbials (DFMs) on cytokine expression patterns, intestinal intraepithelial lymphocyte (IEL) subpopulation, splenocyte proliferation, macrophage functions and resistance against experimental coccidiosis ...

Effect of inclusion of different levels of silage on rumen microbial population and microbial protein synthesis in dairy steers fed on rice straw

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Thien Truong Giang Nguyen

2017-02-01

Full Text Available Objective Leucaena leucocephala (Leucaena is a perennial tropical legume that can be directly grazed or harvested and offered to ruminants as hay, silage, or fresh. However, Leucaena contain phenolic compounds, which are considered anti-nutritional factors as these may reduce intake, digestibility and thus animal performance. Therefore, the objective of this experiment was to determine effects of Leucaena silage (LS feeding levels on rumen microbial populations, N-balance and microbial protein synthesis in dairy steers. Methods Four, rumen fistulated dairy steers with initial weight of 167±12 kg were randomly assigned to receive dietary treatments according to a 4×4 Latin square design. Treatments were as followings: T1 = untreated rice straw (RS; Control, T2 = 70% RS+30% LS, T3 = 40% RS+60% LS, and T4 = 100% LS. Dairy steers were fed rice straw and LS ad libitum and supplemented with concentrate at 0.2% of body weight/d. Results Results revealed that the rumen microbial population, especially cellulolytic, proteolytic bacteria and fungal zoospores were enhanced in steers that received 60% of LS (p0.05. Protozoal population was linearly decreased with increasing level of LS (p<0.05. Moreover, N-balance and microbial protein synthesis were enhanced by LS feeding (p<0.05 and were the highest in 60% LS group. Conclusion Based on this study, it could be concluded that replacement of RS with 60% LS significantly improved microbial population and microbial protein synthesis in diary steers.

Continuously Monocropped Jerusalem Artichoke Changed Soil Bacterial Community Composition and Ammonia-Oxidizing and Denitrifying Bacteria Abundances.

Science.gov (United States)

Zhou, Xingang; Wang, Zhilin; Jia, Huiting; Li, Li; Wu, Fengzhi

2018-01-01

Soil microbial communities have profound effects on the growth, nutrition and health of plants in agroecosystems. Understanding soil microbial dynamics in cropping systems can assist in determining how agricultural practices influence soil processes mediated by microorganisms. In this study, soil bacterial communities were monitored in a continuously monocropped Jerusalem artichoke (JA) system, in which JA was successively monocropped for 3 years in a wheat field. Soil bacterial community compositions were estimated by amplicon sequencing of the 16S rRNA gene. Abundances of ammonia-oxidizing and denitrifying bacteria were estimated by quantitative PCR analysis of the amoA , nirS , and nirK genes. Results showed that 1-2 years of monocropping of JA did not significantly impact the microbial alpha diversity, and the third cropping of JA decreased the microbial alpha diversity ( P < 0.05). Principal coordinates analysis and permutational multivariate analysis of variance analyses revealed that continuous monocropping of JA changed soil bacterial community structure and function profile ( P < 0.001). At the phylum level, the wheat field was characterized with higher relative abundances of Latescibacteria , Planctomycetes , and Cyanobacteria , the first cropping of JA with Actinobacteria , the second cropping of JA with Acidobacteria , Armatimonadetes , Gemmatimonadetes , and Proteobacteria . At the genus level, the first cropping of JA was enriched with bacterial species with pathogen-antagonistic and/or plant growth promoting potentials, while members of genera that included potential denitrifiers increased in the second and third cropping of JA. The first cropping of JA had higher relative abundances of KO terms related to lignocellulose degradation and phosphorus cycling, the second cropping of JA had higher relative abundances of KO terms nitrous-oxide reductase and nitric-oxide reductase, and the third cropping of JA had higher relative abundances of KO terms

Continuously Monocropped Jerusalem Artichoke Changed Soil Bacterial Community Composition and Ammonia-Oxidizing and Denitrifying Bacteria Abundances

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Xingang Zhou

2018-04-01

Full Text Available Soil microbial communities have profound effects on the growth, nutrition and health of plants in agroecosystems. Understanding soil microbial dynamics in cropping systems can assist in determining how agricultural practices influence soil processes mediated by microorganisms. In this study, soil bacterial communities were monitored in a continuously monocropped Jerusalem artichoke (JA system, in which JA was successively monocropped for 3 years in a wheat field. Soil bacterial community compositions were estimated by amplicon sequencing of the 16S rRNA gene. Abundances of ammonia-oxidizing and denitrifying bacteria were estimated by quantitative PCR analysis of the amoA, nirS, and nirK genes. Results showed that 1–2 years of monocropping of JA did not significantly impact the microbial alpha diversity, and the third cropping of JA decreased the microbial alpha diversity (P < 0.05. Principal coordinates analysis and permutational multivariate analysis of variance analyses revealed that continuous monocropping of JA changed soil bacterial community structure and function profile (P < 0.001. At the phylum level, the wheat field was characterized with higher relative abundances of Latescibacteria, Planctomycetes, and Cyanobacteria, the first cropping of JA with Actinobacteria, the second cropping of JA with Acidobacteria, Armatimonadetes, Gemmatimonadetes, and Proteobacteria. At the genus level, the first cropping of JA was enriched with bacterial species with pathogen-antagonistic and/or plant growth promoting potentials, while members of genera that included potential denitrifiers increased in the second and third cropping of JA. The first cropping of JA had higher relative abundances of KO terms related to lignocellulose degradation and phosphorus cycling, the second cropping of JA had higher relative abundances of KO terms nitrous-oxide reductase and nitric-oxide reductase, and the third cropping of JA had higher relative abundances of KO

Coexistence of nitrifying, anammox and denitrifying bacteria in a sequencing batch reactor

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Michela eLangone

2014-02-01

Full Text Available Elevated nitrogen removal efficiencies from ammonium-rich wastewaters have been demonstrated by several applications, that combine nitritation and anammox processes. Denitrification will occur simultaneously when organic carbon is also present. In this study, the activity of aerobic ammonia oxidizing, anammox and denitrifying bacteria in a full scale Sequencing Batch Reactor, treating digester supernatants, was studied by means of batch-assays. AOB and anammox activities were maximum at pH of 8.0 and 7.8-8.0, rispectively. Short term effect of nitrite on anammox activity was studied, showing nitrite up to 42 mg/L did not result in inhibition. Both denitrification via nitrate and nitrite were measured. To reduce nitrite-oxidizing activity, high of NH3 – N (1.9-10 mg N-NH3/L and low nitrite (3-8 mg TNN/L are required conditions during the whole SBR cycle.Molecular analysis showed the nitritation-anammox sludge harbored a high microbial diversity, where each microorganism has a specific role. Using ammonia monooxygenase α –subunit (amoA gene as a marker, our analyses suggested different macro- and micro-environments in the reactor strongly affect the AOB community, allowing the development of different AOB species, such as N. europaea/eutropha and N. oligotropha groups, which improve the stability of nitritation process. A specific PCR primer set, used to target the 16S rRNA gene of anammox bacteria, confirmed the presence of the Ca. Brocadia fulgida type, able to grow in precence of organic matter and to tolerate high nitrite concentrations. The diversity of denitrifiers was assessed by using dissimilatory nitrite reductase (nirS gene-based analyses, who showed denitifiers were related to different betaproteobacterial genera, such as Thauera, Pseudomonas, Dechloromonas and Aromatoleum, able to assist in forming microbial aggregates. Concerning possible secondary processes, no n-damo bacteria were found while NOB from the genus of Nitrobacter

Identification of key nitrous oxide production pathways in aerobic partial nitrifying granules.

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Ishii, Satoshi; Song, Yanjun; Rathnayake, Lashitha; Tumendelger, Azzaya; Satoh, Hisashi; Toyoda, Sakae; Yoshida, Naohiro; Okabe, Satoshi

2014-10-01

The identification of the key nitrous oxide (N2O) production pathways is important to establish a strategy to mitigate N2O emission. In this study, we combined real-time gas-monitoring analysis, (15)N stable isotope analysis, denitrification functional gene transcriptome analysis and microscale N2O concentration measurements to identify the main N2O producers in a partial nitrification (PN) aerobic granule reactor, which was fed with ammonium and acetate. Our results suggest that heterotrophic denitrification was the main contributor to N2O production in our PN aerobic granule reactor. The heterotrophic denitrifiers were probably related to Rhodocyclales bacteria, although different types of bacteria were active in the initial and latter stages of the PN reaction cycles, most likely in response to the presence of acetate. Hydroxylamine oxidation and nitrifier denitrification occurred, but their contribution to N2O emission was relatively small (20-30%) compared with heterotrophic denitrification. Our approach can be useful to quantitatively examine the relative contributions of the three pathways (hydroxylamine oxidation, nitrifier denitrification and heterotrophic denitrification) to N2O emission in mixed microbial populations. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Effects of Andrographis paniculata and Orthosiphon stamineus Supplementation on in-vivo Rumen Fermentation Parameters and Microbial Population in Goats Fed Urea-treated Rice Straw

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Roslan, N.A.

2016-12-01

Full Text Available Four fistulated Boer cross-bred bucks with 25 kg average body weight was used to test the effects of dietary treated rice straw supplemented with A. paniculata and O. stamineus on in-vivo rumen parameters and microbial population in goats. The study was conducted in 4 periods (4 x 4 Latin square design, where each period was for a duration of 22 d; 10 dof adaptation period, 5 dof sampling and 7 dof change-over. The animals were fed once daily at 0800 (3% body weight with 60% of urea-treated rice straw and 40 % of one of four concentrate diets: T1-basal diet + 1% A. paniculata, T2-basal diet + 1% O. stamineus, T3-basal diet + 0.5% of A. paniculata and 0.5% O. stamineus (AO and T4-basal diet without supplementation of herbs. Clean water was provided ad libitum and the animals were individually penned. Rumen contents were sampled at 0, 2, 4, 6 and 12 hafter the onset feeding and the pH was recorded. Rumen pH, VFA's, concentration of ammonia and microbial population in the rumen fluid were measured. The mean rumen pH was the highest (P<0.05 at 2 h in T3 after the onset feeding while the mean concentration (mg/L of ammonia in the rumen fluid was the lowest at 6 and 12 h in T2 (P<0.05. The molar proportion of valerate was higher (P<0.05 at 6 h in T1. Meanwhile, the acetate to propionate ratio was affected by time where it was significantly higher at 12 h in T3. Significant reduction of total protozoa, methanogens, F. succinogens and R. albus number was observed in the herb-supplemented groups (P<0.05. The results suggest that urea-treated rice straw with herbs supplementation can be fed to goats without impairing their performance. However, further study could be done by increasing the supplementation of herbs in order to observe more effective results.

Effect of acetic acid on lipid accumulation by glucose-fed activated sludge cultures

Energy Technology Data Exchange (ETDEWEB)

Mondala, Andro; Hernandez, Rafael; French, Todd; McFarland, Linda; Sparks, Darrell; Holmes, William; Haque, Monica

2012-01-01

The effect of acetic acid, a lignocellulose hydrolysis by-product, on lipid accumulation by activated sludge cultures grown on glucose was investigated. This was done to assess the possible application of lignocellulose as low-cost and renewable fermentation substrates for biofuel feedstock production. Results: Biomass yield was reduced by around 54% at a 2 g L -1 acetic acid dosage but was increased by around 18% at 10 g L -1 acetic acid dosage relative to the control run. The final gravimetric lipid contents at 2 and 10 g L -1 acetic acid levels were 12.5 + 0.7% and 8.8 + 3.2% w/w, respectively, which were lower than the control (17.8 + 2.8% w/w). However, biodiesel yields from activated sludge grown with acetic acid (5.6 + 0.6% w/w for 2 g L -1 acetic acid and 4.2 + 3.0% w/w for 10 g L -1 acetic acid) were higher than in raw activated sludge (1-2% w/w). The fatty acid profiles of the accumulated lipids were similar with conventional plant oil biodiesel feedstocks. Conclusions: Acetic acid enhanced biomass production by activated sludge at high levels but reduced lipid production. Further studies are needed to enhance acetic acid utilization by activated sludge microorganisms for lipid biosynthesis.

Experimental investigation of activities and tolerance of denitrifying bacteria under alkaline and reducing condition

International Nuclear Information System (INIS)

Mine, Tatsuya; Mihara, Morihiro; Ooi, Takao

2000-07-01

In the geological disposal system of TRU wastes, nitrogen generation by denitrifying bacteria could provide significant impact on the assessment of this system, because nitrate contained in process concentrated liquid waste might be electron acceptor for denitrifying bacteria. In this study, the activities and tolerance of denitrifying under disposal condition were investigated. Pseudomonas denitrificans as denitrifying bacteria was used. The results showed that Pseudomonas denitrificans had activity under reducing condition, but under high pH condition (pH>9.5), the activity of Pseudomonas denitrificans was not detected. It is possible that the activity of Pseudomonas denitrificans would be low under disposal condition. (author)

Simultaneous production of acetate and methane from glycerol by selective enrichment of hydrogenotrophic methanogens in extreme-thermophilic (70 °C) mixed culture fermentation

International Nuclear Information System (INIS)

Zhang, Fang; Zhang, Yan; Chen, Yun; Dai, Kun; Loosdrecht, Mark C.M. van; Zeng, Raymond J.

2015-01-01

Highlights: • Simultaneous production of acetate and methane from glycerol was investigated. • Acetate accounted for more than 90% of metabolites in liquid solutions. • The maximum concentration of acetate was above 13 g/L. • 93% of archaea were hydrogenotrophic methanogens. • Thermoanaerobacter was main bacterium and its percentage was 92%. - Abstract: The feasibility of simultaneous production of acetate and methane from glycerol was investigated by selective enrichment of hydrogenotrophic methanogens in an extreme-thermophilic (70 °C) fermentation. Fed-batch experiments showed acetate was produced at the concentration up to 13.0 g/L. A stable operation of the continuous stirred tank reactor (CSTR) was reached within 100 days. Acetate accounted for more than 90 w/w% of metabolites in the fermentation liquid. The yields of methane and acetate were close to the theoretical yields with 0.74–0.80 mol-methane/mol-glycerol and 0.63–0.70 mol-acetate/mol-glycerol. The obtained microbial community was characterized. Hydrogenotrophic methanogens, mainly Methanothermobacter thermautotrophicus formed 93% of the methanogenogenic community. This confirms that a high temperature (70 °C) could effectively select for hydrogenotrophic methanogenic archaea. Thermoanaerobacter spp. was the main bacterium forming 91.5% of the bacterial population. This work demonstrated the conversion of the byproduct of biodiesel production, glycerol, to acetate as a chemical and biogas for energy generation

The variation of power generation with organic substrates in single-chamber microbial fuel cells (SCMFCs).

Science.gov (United States)

Sharma, Yogesh; Li, Baikun

2010-03-01

The wastewaters consist of diverse types of organic substrates that can be used as the carbon sources for power generation. To explore the utilization of some of these organics, the electricity generation from three substrates (acetate, ethanol, and glucose) was examined over a concentration range of 0.5-35 mM in single-chamber microbial fuel cells (SCMFCs). The power density generated from glucose was the highest at 401 mW/m(2) followed by acetate and ethanol at 368 mW/m(2) and 302 mW/m(2), respectively. The voltage increased with substrate concentration of 0.5-20mM, but significantly decreased at high substrate concentrations of 20-35 mM. Kinetic analysis indicated that the inhibition in the ethanol-fed MFCs was the highest at the concentration of 35 mM, while inhibition in glucose-fed MFCs was the lowest at the concentration of 20mM. These were in accordance with the extents of voltage decrease at high substrate concentration. Moreover, the effect of the distance between anode and cathode on voltage generation was also investigated. The reduction of the electrode distance by 33% in the glucose-fed MFCs reduced the internal resistance by 73% and led to 20% increase in voltage generation. Published by Elsevier Ltd.

Reduced Nutrient Excretion and Environmental Microbial Load with the Addition of a Combination of Enzymes and Direct-Fed Microbials to the Diet of Broiler Chickens

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MFFM Praes

2016-03-01

Full Text Available Abstract This study evaluated the effects of the dietary inclusion of an enzyme blend and a direct-fed microbials in broiler diets on litter production and quality. In total, 900 Cobb 500(r broiler chicks were distributed according to a completely randomized design into 4 treatments and 9 replicates of 25 birds each. Broilers were reared from 1 to 42 days of age. The treatments consisted of the following diets: NC: negative control; DFM: NC + 500 ppm of direct-fed microbials product (DFM, containing Bacillus subtilis and Bacillus licheniformis; ENZ: diet formulated with an enzyme blend (20 ppm phytase, 200 ppm protease and 200 ppm of xylanase; DFM+E: ENZ + DFM. Birds and litter were weighed at the start and end of the rearing period, for litter production and waste ratio (Rw determination. Litter samples were analyzed for dry matter (DM content, total and thermotolerant coliform counts, nutrient composition (nitrogen (N, phosphorous (P and potassium (K, and fiber fraction (neutral detergent fiber (NDF, acid detergent fiber (ADF and lignin. The dietary inclusion of the evaluated additivesdid not influence litter production or Rw; however, ADF (%, NDF (kg and kg/kg DM litter, and total and thermotolerant coliform counts were reduced, and N content increased in the litter. The diets containing enzymes (ENZ and DFM+E reduced litter P content. The addition of exogenous enzymes and their combination with a DFM based on Bacillus spp .Did not affect waste production, and reduced litter microbial load, and the contents of P and insoluble fiber in the litter.

Effect of Bacillus subtilis-based direct-fed microbials on immune status in broiler chickens raised on fresh or used litter

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The type of dietary direct-fed microbials (DFMs) or poultry litter could directly influence the composition of gut microbiota. Gut microbiota play an important role in shaping the developing immune system and maintaining homeostasis of the mature immune system in mammal and chickens. The present stu...

The activity and community structure of total bacteria and denitrifying bacteria across soil depths and biological gradients in estuary ecosystem.

Science.gov (United States)

Lee, Seung-Hoon; Kang, Hojeong

2016-02-01

The distribution of soil microorganisms often shows variations along soil depth, and even in the same soil layer, each microbial group has a specific niche. In particular, the estuary soil is intermittently flooded, and the characteristics of the surface soil layer are different from those of other terrestrial soils. We investigated the microbial community structure and activity across soil depths and biological gradients composed of invasive and native plants in the shallow surface layer of an estuary ecosystem by using molecular approaches. Our results showed that the total and denitrifying bacterial community structures of the estuarine wetland soil differed according to the short depth gradient. In growing season, gene copy number of 16S rRNA were 1.52(±0.23) × 10(11), 1.10(±0.06) × 10(11), and 4.33(±0.16) × 10(10) g(-1) soil; nirS were 5.41(±1.25) × 10(8), 4.93(±0.94) × 10(8), and 2.61(±0.28) × 10(8) g(-1) soil; and nirK were 9.67(±2.37) × 10(6), 3.42(±0.55) × 10(6), and 2.12(±0.19) × 10(6) g(-1) soil in 0 cm, 5 cm, and 10 cm depth layer, respectively. The depth-based difference was distinct in the vegetated sample and in the growing season, evidencing the important role of plants in structuring the microbial community. In comparison with other studies, we observed differences in the microbial community and functions even across very short depth gradients. In conclusion, our results suggested that (i) in the estuary ecosystem, the denitrifying bacterial community could maintain its abundance and function within shallow surface soil layers through facultative anaerobiosis, while the total bacterial community would be both quantitatively and qualitatively affected by the soil depth, (ii) the nirS gene community, rather than the nirK one, should be the first candidate used as an indicator of the microbial denitrification process in the estuary system, and (iii) as the microbial community is distributed and plays a certain niche role according to

Ammonia-Oxidizing Archaea Are More Resistant Than Denitrifiers to Seasonal Precipitation Changes in an Acidic Subtropical Forest Soil

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Jie Chen

2017-07-01

Full Text Available Seasonal precipitation changes are increasingly severe in subtropical areas. However, the responses of soil nitrogen (N cycle and its associated functional microorganisms to such precipitation changes remain unclear. In this study, two projected precipitation patterns were manipulated: intensifying the dry-season drought (DD and extending the dry-season duration (ED but increasing the wet-season storms following the DD and ED treatment period. The effects of these two contrasting precipitation patterns on soil net N transformation rates and functional gene abundances were quantitatively assessed through a resistance index. Results showed that the resistance index of functional microbial abundance (-0.03 ± 0.08 was much lower than that of the net N transformation rate (0.55 ± 0.02 throughout the experiment, indicating that microbial abundance was more responsive to precipitation changes compared with the N transformation rate. Spring drought under the ED treatment significantly increased the abundances of both nitrifying (amoA and denitrifying genes (nirK, nirS, and nosZ, while changes in these gene abundances overlapped largely with control treatment during droughts in the dry season. Interestingly, the resistance index of the ammonia-oxidizing archaea (AOA amoA abundance was significantly higher than that of the denitrifying gene abundances, suggesting that AOA were more resistant to the precipitation changes. This was attributed to the stronger environmental adaptability and higher resource utilization efficiency of the AOA community, as indicated by the lack of correlations between AOA gene abundance and environmental factors [i.e., soil water content, ammonium (NH4+ and dissolved organic carbon concentrations] during the experiment.

Denitrifying bacteria from the genus Rhodanobacter dominate bacterial communities in the highly contaminated subsurface of a nuclear legacy waste site

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Green, Stefan [Florida State University; Prakash, Om [Florida State University; Jasrotia, Puja [Florida State University; Overholt, Will [Florida State University; Cardenas, Erick [Michigan State University, East Lansing; Hubbard, Daniela [Florida State University; Tiedje, James M. [Michigan State University, East Lansing; Watson, David B [ORNL; Schadt, Christopher Warren [ORNL; Brooks, Scott C [ORNL; Kostka, Joel [Florida State University

2011-01-01

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of ribosomal RNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure, and denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as concentration of nitrogen species, oxygen and sampling season did not appear to strongly influence the distribution of Rhodanobacter. Results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment.

Effects of cinnamaldehyde and garlic oil on rumen microbial fermentation in a dual flow continuous culture.

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Busquet, M; Calsamiglia, S; Ferret, A; Cardozo, P W; Kamel, C

2005-07-01

Eight continuous culture fermentors inoculated with ruminal liquor from heifers fed a 50:50 alfalfa hay:concentrate diet (17.6% crude protein, 28.0% neutral detergent fiber) were used in 3 replicated periods to study the effects of cinnamaldehyde (CIN) and garlic oil (GAR) on rumen microbial fermentation. Treatments were no additive (negative control); 1.25 mg/L (MON) and 12.5 mg/L (MON10) of the ionophore antibiotic monensin (positive control); 31.2 mg/L CIN (CIN) and 312 mg/L (CIN10) of CIN; and 31.2 mg/L GAR (GAR) and 312 mg/L (GAR10) of GAR (Allium sativa). The MON10 caused expected changes in microbial fermentation patterns (a decrease in fiber digestion, ammonia N concentration, and proportions of acetate and butyrate; an increase in the proportion of propionate; and a trend to increase small peptide plus AA N concentration). The CIN decreased the proportion of acetate and branch-chained volatile fatty acids (VFA) and increased the proportion of propionate; CIN10 decreased the proportion of acetate and increased the proportion of butyrate compared with the control. The GAR10 increased the proportion of propionate and butyrate and decreased the proportion of acetate and branch-chained VFA compared with the control. The GAR10 also increased the small peptide plus amino acid N concentration, although no effects were observed on large peptides or ammonia N concentrations. The CIN and GAR10 resulted in similar effects as monensin, with the exception of the effects on the molar proportion of butyrate, which suggests that they might have a different mode of action in affecting in vitro microbial fermentation.

Modeling the formation of soluble microbial products (SMP in drinking water biofiltration

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Yu Xin

2008-09-01

Full Text Available Both a theoretical and an empirical model were developed for predicting the formation of soluble microbial products (SMP during drinking water biofiltration. Four pilot-scale biofilters with ceramsite as the medium were fed with different acetate loadings for the determination of SMP formation. Using numerically simulated and measured parameters, the theoretical model was developed according to the substrate and biomass balance. The results of this model matched the measured data better for higher SMP formation but did not fit well when SMP formation was lower. In order to better simulate the reality and overcome the difficulties of measuring the kinetic parameters, a simpler empirical model was also developed. In this model, SMP formation was expressed as a function of fed organic loadings and the depth of the medium, and a much better fit was obtained.

Microbial uptake of uranium, cesium, and radium

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Strandberg, G.W.; Shumate, S.E. II; Parrott, J.R. Jr.; McWhirter, D.A.

1980-01-01

The ability of diverse microbial species to concentrate uranium, cesium, and radium was examined. Saccharomyces cerevisiae, Pseudomonas aeruginosa, and a mixed culture of denitrifying bacteria accumulated uranium to 10 to 15% of the dry cell weight. Only a fraction of the cells in a given population had visible uranium deposits in electron micrographs. While metabolism was not required for uranium uptake, mechanistic differences in the metal uptake process were indicated. Uranium accumulated slowly (hours) on the surface of S. cerevisiae and was subject to environmental factors (i.e., temperature, pH, interfering cations and anions). In contrast, P. aeruginosa and the mixed culture of denitrifying bacteria accumulated uranium rapidly (minutes) as dense, apparently random, intracellular deposits. This very rapid accumulation has prevented us from determining whether the uptake rate during the transient between the initial and equilibrium distribution of uranium is affected by environmental conditions. However, the final equilibrium distributions are not affected by those conditions which affect uptake by S. cerevisiae. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several microbial species tested. The potential utility of microorganisms for the removal and concentration of these metals from nuclear processing wastes and several bioreactor designs for contacting microorganisms with contaminated waste streams will be discussed.

Novel Large Sulfur Bacteria in the Metagenomes of Groundwater-Fed Chemosynthetic Microbial Mats in the Lake Huron Basin.

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Sharrar, Allison M; Flood, Beverly E; Bailey, Jake V; Jones, Daniel S; Biddanda, Bopaiah A; Ruberg, Steven A; Marcus, Daniel N; Dick, Gregory J

2017-01-01

Little is known about large sulfur bacteria (LSB) that inhabit sulfidic groundwater seeps in large lakes. To examine how geochemically relevant microbial metabolisms are partitioned among community members, we conducted metagenomic analysis of a chemosynthetic microbial mat in the Isolated Sinkhole, which is in a deep, aphotic environment of Lake Huron. For comparison, we also analyzed a white mat in an artesian fountain that is fed by groundwater similar to Isolated Sinkhole, but that sits in shallow water and is exposed to sunlight. De novo assembly and binning of metagenomic data from these two communities yielded near complete genomes and revealed representatives of two families of LSB. The Isolated Sinkhole community was dominated by novel members of the Beggiatoaceae that are phylogenetically intermediate between known freshwater and marine groups. Several of these Beggiatoaceae had 16S rRNA genes that contained introns previously observed only in marine taxa. The Alpena fountain was dominated by populations closely related to Thiothrix lacustris and an SM1 euryarchaeon known to live symbiotically with Thiothrix spp. The SM1 genomic bin contained evidence of H 2 -based lithoautotrophy. Genomic bins of both the Thiothrix and Beggiatoaceae contained genes for sulfur oxidation via the rDsr pathway, H 2 oxidation via Ni-Fe hydrogenases, and the use of O 2 and nitrate as electron acceptors. Mats at both sites also contained Deltaproteobacteria with genes for dissimilatory sulfate reduction ( sat, apr , and dsr ) and hydrogen oxidation (Ni-Fe hydrogenases). Overall, the microbial mats at the two sites held low-diversity microbial communities, displayed evidence of coupled sulfur cycling, and did not differ largely in their metabolic potentials, despite the environmental differences. These results show that groundwater-fed communities in an artesian fountain and in submerged sinkholes of Lake Huron are a rich source of novel LSB, associated heterotrophic and sulfate

Novel Large Sulfur Bacteria in the Metagenomes of Groundwater-Fed Chemosynthetic Microbial Mats in the Lake Huron Basin

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Allison M. Sharrar

2017-05-01

Full Text Available Little is known about large sulfur bacteria (LSB that inhabit sulfidic groundwater seeps in large lakes. To examine how geochemically relevant microbial metabolisms are partitioned among community members, we conducted metagenomic analysis of a chemosynthetic microbial mat in the Isolated Sinkhole, which is in a deep, aphotic environment of Lake Huron. For comparison, we also analyzed a white mat in an artesian fountain that is fed by groundwater similar to Isolated Sinkhole, but that sits in shallow water and is exposed to sunlight. De novo assembly and binning of metagenomic data from these two communities yielded near complete genomes and revealed representatives of two families of LSB. The Isolated Sinkhole community was dominated by novel members of the Beggiatoaceae that are phylogenetically intermediate between known freshwater and marine groups. Several of these Beggiatoaceae had 16S rRNA genes that contained introns previously observed only in marine taxa. The Alpena fountain was dominated by populations closely related to Thiothrix lacustris and an SM1 euryarchaeon known to live symbiotically with Thiothrix spp. The SM1 genomic bin contained evidence of H2-based lithoautotrophy. Genomic bins of both the Thiothrix and Beggiatoaceae contained genes for sulfur oxidation via the rDsr pathway, H2 oxidation via Ni-Fe hydrogenases, and the use of O2 and nitrate as electron acceptors. Mats at both sites also contained Deltaproteobacteria with genes for dissimilatory sulfate reduction (sat, apr, and dsr and hydrogen oxidation (Ni-Fe hydrogenases. Overall, the microbial mats at the two sites held low-diversity microbial communities, displayed evidence of coupled sulfur cycling, and did not differ largely in their metabolic potentials, despite the environmental differences. These results show that groundwater-fed communities in an artesian fountain and in submerged sinkholes of Lake Huron are a rich source of novel LSB, associated heterotrophic

Propionate oxidation by and methanol inhibition of anaerobic ammonium-oxidizing bacteria.

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Güven, Didem; Dapena, Ana; Kartal, Boran; Schmid, Markus C; Maas, Bart; van de Pas-Schoonen, Katinka; Sozen, Seval; Mendez, Ramon; Op den Camp, Huub J M; Jetten, Mike S M; Strous, Marc; Schmidt, Ingo

2005-02-01

Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway and a cost-effective way to remove ammonium from wastewater. Anammox bacteria have been described as obligate chemolithoautotrophs. However, many chemolithoautotrophs (i.e., nitrifiers) can use organic compounds as a supplementary carbon source. In this study, the effect of organic compounds on anammox bacteria was investigated. It was shown that alcohols inhibited anammox bacteria, while organic acids were converted by them. Methanol was the most potent inhibitor, leading to complete and irreversible loss of activity at concentrations as low as 0.5 mM. Of the organic acids acetate and propionate, propionate was consumed at a higher rate (0.8 nmol min(-1) mg of protein(-1)) by Percoll-purified anammox cells. Glucose, formate, and alanine had no effect on the anammox process. It was shown that propionate was oxidized mainly to CO(2), with nitrate and/or nitrite as the electron acceptor. The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. In an anammox enrichment culture fed with propionate for 150 days, the relative amounts of anammox cells and denitrifiers did not change significantly over time, indicating that anammox bacteria could compete successfully with heterotrophic denitrifiers for propionate. In conclusion, this study shows that anammox bacteria have a more versatile metabolism than previously assumed.

Effects of carbon sources on the enrichment of halophilic polyhydroxyalkanoate-storing mixed microbial culture in an aerobic dynamic feeding process

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Cui, You-Wei; Zhang, Hong-Yu; Lu, Peng-Fei; Peng, Yong-Zhen

2016-08-01

Microbial polyhydroxyalkanoate (PHA) production serves as a substitute for petroleum-based plastics. Enriching mixed microbial cultures (MMCs) with the capacity to store PHA is a key precursor for low-cost PHA production. This study investigated the impact of carbon types on enrichment outcomes. Three MMCs were separately fed by acetate sodium, glucose, and starch as an enriching carbon source, and were exposed to long-term aerobic dynamic feeding (ADF) periods. The PHA production capacity, kinetics and stoichiometry of the enrichments, the PHA composition, and the microbial diversity and community composition were explored to determine carbon and enrichment correlations. After 350-cycle enriching periods under feast-famine (F-F) regimes, the MMCs enriched by acetate sodium and glucose contained a maximum PHA content of 64.7% and 60.5% cell dry weight (CDW). The starch-enriched MMC only had 27.3% CDW of PHA. High-throughput sequencing revealed that non-PHA bacteria survived alongside PHA storing bacteria, even under severe F-F selective pressure. Genus of Pseudomonas and Stappia were the possible PHA accumulating bacteria in acetate-enriched MMC. Genus of Oceanicella, Piscicoccus and Vibrio were found as PHA accumulating bacteria in glucose-enriched MMC. Vibrio genus was the only PHA accumulating bacteria in starch-enriched MMC. The community diversity and composition were regulated by the substrate types.

Analysis of microbial community variation during the mixed culture fermentation of agricultural peel wastes to produce lactic acid.

Science.gov (United States)

Liang, Shaobo; Gliniewicz, Karol; Gerritsen, Alida T; McDonald, Armando G

2016-05-01

Mixed cultures fermentation can be used to convert organic wastes into various chemicals and fuels. This study examined the fermentation performance of four batch reactors fed with different agricultural (orange, banana, and potato (mechanical and steam)) peel wastes using mixed cultures, and monitored the interval variation of reactor microbial communities with 16S rRNA genes using Illumina sequencing. All four reactors produced similar chemical profile with lactic acid (LA) as dominant compound. Acetic acid and ethanol were also observed with small fractions. The Illumina sequencing results revealed the diversity of microbial community decreased during fermentation and a community of largely lactic acid producing bacteria dominated by species of Lactobacillus developed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biotransformation of (-)-dihydromyrcenyl acetate using the plant parasitic fungus Glomerella cingulata as a biocatalyst.

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Miyazawa, M; Akazawa, S i; Sakai, H; Nankai, H

2000-10-01

The microbial transformation of (-)-dihydromyrcenyl acetate was investigated using the plant parasitic fungus Glomerella cingulata. As a result, (-)-dihydromyrcenyl acetate was converted to dihydromyrcenol, 3,7-dihydroxy-3,7-dimethyl-1-octene-7-carboxylate, 3,7-dihydroxy-3,7-dimethyl-1-octene, 3,7-dimethyloctane-1,2, 7-triol-7-carboxylate, and 3,7-dimethyloctane-1,2,7-triol. In addition, microbial transformation of dihydromyrcenol by G. cingulata was carried out. The metabolic pathway of (-)-dihydromyrcenyl acetate is discussed.

Model-based intensification of a fed-batch microbial process for the maximization of polyhydroxybutyrate (PHB) production rate.

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Penloglou, Giannis; Vasileiadou, Athina; Chatzidoukas, Christos; Kiparissides, Costas

2017-08-01

An integrated metabolic-polymerization-macroscopic model, describing the microbial production of polyhydroxybutyrate (PHB) in Azohydromonas lata bacteria, was developed and validated using a comprehensive series of experimental measurements. The model accounted for biomass growth, biopolymer accumulation, carbon and nitrogen sources utilization, oxygen mass transfer and uptake rates and average molecular weights of the accumulated PHB, produced under batch and fed-batch cultivation conditions. Model predictions were in excellent agreement with experimental measurements. The validated model was subsequently utilized to calculate optimal operating conditions and feeding policies for maximizing PHB productivity for desired PHB molecular properties. More specifically, two optimal fed-batch strategies were calculated and experimentally tested: (1) a nitrogen-limited fed-batch policy and (2) a nitrogen sufficient one. The calculated optimal operating policies resulted in a maximum PHB content (94% g/g) in the cultivated bacteria and a biopolymer productivity of 4.2 g/(l h), respectively. Moreover, it was demonstrated that different PHB grades with weight average molecular weights of up to 1513 kg/mol could be produced via the optimal selection of bioprocess operating conditions.

Implication of using different carbon sources for denitrification in wastewater treatments.

Science.gov (United States)

Cherchi, Carla; Onnis-Hayden, Annalisa; El-Shawabkeh, Ibrahim; Gu, April Z

2009-08-01

Application of external carbon sources for denitrification becomes necessary for wastewater treatment plants that have to meet very stringent effluent nitrogen limits (e.g., 3 to 5 mgTN/L). In this study, we evaluated and compared three carbon sources--MicroC (Environmental Operating Solutions, Bourne, Massachusetts), methanol, and acetate-in terms of their denitrification rates and kinetics, effect on overall nitrogen removal performance, and microbial community structure of carbon-specific denitrifying enrichments. Denitrification rates and kinetics were determined with both acclimated and non-acclimated biomass, obtained from laboratory-scale sequencing batch reactor systems or full-scale plants. The results demonstrate the feasibility of the use of MicroC for denitrification processes, with maximum denitrification rates (k(dmax)) of 6.4 mgN/gVSSh and an observed yield of 0.36 mgVSS/mgCOD. Comparable maximum nitrate uptake rates were found with methanol, while acetate showed a maximum denitrification rate nearly twice as high as the others. The maximum growth rates measured at 20 degrees C for MicroC and methanol were 3.7 and 1.2 day(-1), respectively. The implications resulting from the differences in the denitrification rates and kinetics of different carbon sources on the full-scale nitrogen removal performance, under various configurations and operational conditions, were assessed using Biowin (EnviroSim Associates, Ltd., Flamborough, Ontario, Canada) simulations for both pre- and post-denitrification systems. Examination of microbial population structures using Automated Ribosomal Intergenic Spacer Analysis (ARISA) throughout the study period showed dynamic temporal changes and distinct microbial community structures of different carbon-specific denitrifying cultures. The ability of a specific carbon-acclimated denitrifying population to instantly use other carbon source also was investigated, and the chemical-structure-associated behavior patterns observed

Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

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Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

2016-10-01

Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3-64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7-25.4%), Firmicutes (3.0-20.1%), Acidobacteria (2.7-15.7%), Actinobacteria (2.2-8.7%), Bacteroidetes (0.5-9.7%), and Verrucomicrobia (2.4-5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

Are Isotopologue Signatures of N2O from Bacterial Denitrifiers Indicative of NOR Type?

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Well, R.; Braker, G.; Giesemann, A.; Flessa, H.

2010-12-01

Nitrous oxide (N2O) fluxes from soils result from its production by nitrification and denitrification and reduction during denitrification. The structure of the denitrifying microbial community contributes to the control of net N2O fluxes. Although molecular techniques are promising for identifying the active community of N2O producers, there are few data until now because methods to explore gene expression of N2O production are laborious and disregard regulation of activity at the enzyme level. The isotopologue signatures of N2O including δ18O, average δ15N (δ15Nbulk) and 15N site preference (SP = difference in δ15N between the central and peripheral N positions of the asymmetric N2O molecule) have been used to estimate the contribution of partial processes to net N2O fluxes to the atmosphere. However, the use of this approach to study N2O dynamics in soils requires knowledge of isotopic signatures of N2O precursors and isotopologue fractionation factors (ɛ) of all processes of N2O production and consumption. In contrast to δ18O and δ15Nbulk, SP is independent of precursor signatures and hence is a promising parameter here. It is assumed that SP of produced N2O is almost exclusively controlled by the enzymatic isotope effects of NO reductases (NOR). These enzymes are known to be structurally different between certain classes of N2O producers with each class causing different isotope effects (Schmidt et al., 2004). The NH2OH-to-N2O step of nitrifiers and the NO3-to-N2O step of fungal denitrifiers are associated with large site-specific 15N effects with SP of 33 to 37 ‰ (Sutka et al., 2006, 2008) while the few tested species of gram-negative bacterial denitrifiers (cNOR group) exhibited low SP of -5 to 0‰ (Sutka et al., 2006; Toyoda et al., 2005). The aim of our study was to determine site-specific fractionation factors of the NO3-to-N2O step (ɛSP) for several species of denitrifiers representing each of the known NOR-types of bacteria, i.e. cNOR, q

Effects of microbial phytase on apparent and standardized total tract digestibility of calcium in calcium supplements fed to growing pigs.

Science.gov (United States)

González-Vega, J C; Walk, C L; Stein, H H

2015-05-01

An experiment was conducted to test the hypothesis that differences in the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of Ca exist among Ca supplements and that inclusion of microbial phytase increases the ATTD and STTD of Ca. One hundred and four growing barrows (average initial BW of 17.73 ± 2.53 kg) were allotted to a randomized complete block design with 13 dietary treatments and 8 pigs per treatment. A basal diet containing corn, cornstarch, potato protein isolate, soybean oil, calcium carbonate, monosodium phosphate, vitamins, and minerals was formulated. Five additional diets were formulated by adding monocalcium phosphate (MCP), dicalcium phosphate (DCP), calcium carbonate, Lithothamnium calcareum Ca, or a high-Ca sugar beet co-product to the basal diet at the expense of cornstarch. Six additional diets that were similar to the previous 6 diets with the exception that they also contained 500 units per kilogram of microbial phytase were also formulated. A Ca-free diet was used to determine basal endogenous losses of Ca. Feces were collected using the marker-to-marker approach. Results indicated that regardless of inclusion of microbial phytase, MCP had the greatest (P calcareum Ca, or sugar beet co-product. Inclusion of microbial phytase increased (P calcareum Ca, or the sugar beet co-product, but pigs fed calcium carbonate diets had greater ( P< 0.05) ATTD of P than pigs fed L. calcareumCa or the sugar beet co-product. Regardless of Ca source, inclusion of microbial phytase increased (P < 0.001) the ATTD of P. In conclusion, MCP has the greatest ATTD and STTD of Ca among the calcium supplements used in this experiment, followed by DCP. Basal, MCP, and DCP diets had greater ATTD of P than the other diets, and inclusion of microbial phytase increased the ATTD and STTD of Ca and the ATTD of P in the diets.

Evaluation of a Bacillus direct-fed microbial candidate on digesta viscosity, bacterial translocation, microbiota composition and bone mineralisation in broiler chickens fed on a rye-based diet.

Science.gov (United States)

Latorre, J D; Hernandez-Velasco, X; Bielke, L R; Vicente, J L; Wolfenden, R; Menconi, A; Hargis, B M; Tellez, G

2015-01-01

1. The effects of the dietary inclusion of a Bacillus-based direct-fed microbial (DFM) candidate on digesta viscosity, bacterial translocation, microbiota composition and bone mineralisation were evaluated in broilers consuming rye-based diets. 2. In the present study, control mash rye-based diets (CON) or Bacillus-DFM supplemented diets (TRT) were administered ad libitum to male broilers in three independent experiments. 3. In Experiments 1 and 2 (n = 25/group), liver samples were taken to evaluate bacterial translocation, digesta samples were used for viscosity measurements and the intestinal microbial flora was evaluated from different intestinal sections to enumerate total recovered gram-negative bacteria (TGB), lactic acid bacteria (LAB) and anaerobic bacteria (TAB). Additionally, both tibias were removed for assessment of bone quality. 4. In Experiment 3, each experimental group had 8 replicates of 20 chickens (n = 160/group). Weekly, body weight (BW), feed intake (FI) and feed conversion ratio (FCR) were evaluated. At d 28-of-age, samples were taken to determine bacterial translocation, digesta viscosity and bone quality characteristics. 5. In all experiments, consumption of Bacillus-DFM reduced bacterial translocation to the liver and digesta viscosity. Additionally, DFM supplementation improved BW, bone quality measurements and FCR. Moreover, chickens fed on the Bacillus-DFM diet in Experiments 1 and 2 showed a significant reduction in the number of gram-negative and anaerobic bacteria in the duodenal content compared to control. 6. In summary, chickens fed on a rye-based diet without DFM inclusion showed an increase in bacterial translocation and digesta viscosity, accompanied by reduced performance and bone quality variables relative to the Bacillus-DFM candidate group. Hence, incorporation into the feed of a selected DFM ameliorated the adverse anti-nutritional effects related to utilisation of rye-based diets in broilers chickens.

Peran Direct Fed Microbials (DFM Saccharomyces cerevisiae dan Aspergillus oryzae terhadap Produktivitas Ternak Ruminansia : Review

Directory of Open Access Journals (Sweden)

H. Suryani

2015-02-01

Full Text Available Mikroorganisme yang biasa digunakan dalam pakan ternak ruminansia biasanya berupa probiotik. Probiotik memiliki makna yang bersepadanan dengan Direct Fed Microbials (DFM. Penambahan DFM jenis Saccharomyces cerevisiae dan Aspergillus oryzae pada pakan ternak ruminansia mampu memanipulasi rumen dengan meningkatkan populasi bakteri pemecah serat sehingga dapat meningkatkan kecernaan dan meningkatkan bobot badan. Mekanisme kerja S. cerevisiae dan A. oryzae yang masuk kedalam tubuh ternak dan mempengaruhi pencernaan atau penyerapan, ada yang sudah diketahui secara jelas tetapi ada juga yang masih berupa hipotesa. Pemanfaatan DFM jenis S. cerevisiae dan A. oryzae secara tunggal maupun kombinasi sebagian telah diamati dan memberikan respon positif.

Acetate production from whey lactose using co-immobilized cells of homolactic and homoacetic bacteria in a fibrous-bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

Huang, Y.; Yang, S.T. [Ohio State Univ., Columbus, OH (United States). Dept. of Chemical Engineering

1998-11-20

Acetate was produced from whey lactose in batch and fed-batch fermentations using co-immobilized cells of Clostridium formicoaceticum and Lactococcus lactis. The cells were immobilized in a spirally wound fibrous sheet packed in a 0.45-L column reactor, with liquid circulated through a 5-L stirred-tank fermentor. Industrial-grade nitrogen sources, including corn steep liquor, casein hydrolysate, and yeast hydrolysate, were studied as inexpensive nutrient supplements to whey permeate and acid whey. Supplementation with either 2.5% (v/v) corn steep liquor or 1.5 g/L casein hydrolysate was adequate for the cocultured fermentation. The overall acetic acid yield from lactose was 0.9 g/g, and the productivity was 0.25 g/(L h). Both lactate and acetate at high concentrations inhibited the homoacetic fermentation. To overcome these inhibitions, fed-batch fermentations were used to keep lactate concentration low and to adapt cells to high-concentration acetate. The final acetate concentration obtained in the fed-batch fermentations were used to keep lactate concentration low and to adapt cells to high-concentration acetate. The final acetate concentration obtained in the fed-batch fermentation was 75 g/L, which was the highest acetate concentration ever produced by C. formicoaceticum. Even at this high acetate concentration, the overall productivity was 0.18 g/(L h) based on the total medium volume and 1.23 g/(L h) based on the fibrous-bed reactor volume. The cells isolated from the fibrous-bed bioreactor at the end of this study were more tolerant to acetic acid than the original culture used to seed the bioreactor, indicating that adaptation and natural selection of acetate-tolerant strains occurred. This cocultured fermentation process could be used to produce a low-cost acetate deicer from whey permeate and acid whey.

Denitrifying bacteria from the genus Rhodanobacter dominate bacterial communities in the highly contaminated subsurface of a nuclear legacy waste site.

Science.gov (United States)

Green, Stefan J; Prakash, Om; Jasrotia, Puja; Overholt, Will A; Cardenas, Erick; Hubbard, Daniela; Tiedje, James M; Watson, David B; Schadt, Christopher W; Brooks, Scott C; Kostka, Joel E

2012-02-01

The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface was investigated at the field scale at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN. The abundance, community composition, and distribution of groundwater microorganisms were examined across the site during two seasonal sampling events. At representative locations, subsurface sediment was also examined from two boreholes, one sampled from the most heavily contaminated area of the site and another from an area with low contamination. A suite of DNA- and RNA-based molecular tools were employed for community characterization, including quantitative PCR of rRNA and nitrite reductase genes, community composition fingerprinting analysis, and high-throughput pyrotag sequencing of rRNA genes. The results demonstrate that pH is a major driver of the subsurface microbial community structure and that denitrifying bacteria from the genus Rhodanobacter (class Gammaproteobacteria) dominate at low pH. The relative abundance of bacteria from this genus was positively correlated with lower-pH conditions, and these bacteria were abundant and active in the most highly contaminated areas. Other factors, such as the concentration of nitrogen species, oxygen level, and sampling season, did not appear to strongly influence the distribution of Rhodanobacter bacteria. The results indicate that these organisms are acid-tolerant denitrifiers, well suited to the acidic, nitrate-rich subsurface conditions, and pH is confirmed as a dominant driver of bacterial community structure in this contaminated subsurface environment.

Petrophilic, Fe(III Reducing Exoelectrogen Citrobacter sp. KVM11, Isolated From Hydrocarbon Fed Microbial Electrochemical Remediation Systems

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Krishnaveni Venkidusamy

2018-03-01

Full Text Available Exoelectrogenic biofilms capable of extracellular electron transfer are important in advanced technologies such as those used in microbial electrochemical remediation systems (MERS Few bacterial strains have been, nevertheless, obtained from MERS exoelectrogenic biofilms and characterized for bioremediation potential. Here we report the identification of one such bacterial strain, Citrobacter sp. KVM11, a petrophilic, iron reducing bacterial strain isolated from hydrocarbon fed MERS, producing anodic currents in microbial electrochemical systems. Fe(III reduction of 90.01 ± 0.43% was observed during 5 weeks of incubation with Fe(III supplemented liquid cultures. Biodegradation screening assays showed that the hydrocarbon degradation had been carried out by metabolically active cells accompanied by growth. The characteristic feature of diazo dye decolorization was used as a simple criterion for evaluating the electrochemical activity in the candidate microbe. The electrochemical activities of the strain KVM11 were characterized in a single chamber fuel cell and three electrode electrochemical cells. The inoculation of strain KVM11 amended with acetate and citrate as the sole carbon and energy sources has resulted in an increase in anodic currents (maximum current density of 212 ± 3 and 359 ± mA/m2 with respective coulombic efficiencies of 19.5 and 34.9% in a single chamber fuel cells. Cyclic voltammetry studies showed that anaerobically grown cells of strain KVM11 are electrochemically active whereas aerobically grown cells lacked the electrochemical activity. Electrobioremediation potential of the strain KVM11 was investigated in hydrocarbonoclastic and dye detoxification conditions using MERS. About 89.60% of 400 mg l-1 azo dye was removed during the first 24 h of operation and it reached below detection limits by the end of the batch operation (60 h. Current generation and biodegradation capabilities of strain KVM11 were examined using an

Petrophilic, Fe(III) Reducing Exoelectrogen Citrobacter sp. KVM11, Isolated From Hydrocarbon Fed Microbial Electrochemical Remediation Systems

Science.gov (United States)

Venkidusamy, Krishnaveni; Hari, Ananda Rao; Megharaj, Mallavarapu

2018-01-01

Exoelectrogenic biofilms capable of extracellular electron transfer are important in advanced technologies such as those used in microbial electrochemical remediation systems (MERS) Few bacterial strains have been, nevertheless, obtained from MERS exoelectrogenic biofilms and characterized for bioremediation potential. Here we report the identification of one such bacterial strain, Citrobacter sp. KVM11, a petrophilic, iron reducing bacterial strain isolated from hydrocarbon fed MERS, producing anodic currents in microbial electrochemical systems. Fe(III) reduction of 90.01 ± 0.43% was observed during 5 weeks of incubation with Fe(III) supplemented liquid cultures. Biodegradation screening assays showed that the hydrocarbon degradation had been carried out by metabolically active cells accompanied by growth. The characteristic feature of diazo dye decolorization was used as a simple criterion for evaluating the electrochemical activity in the candidate microbe. The electrochemical activities of the strain KVM11 were characterized in a single chamber fuel cell and three electrode electrochemical cells. The inoculation of strain KVM11 amended with acetate and citrate as the sole carbon and energy sources has resulted in an increase in anodic currents (maximum current density) of 212 ± 3 and 359 ± mA/m2 with respective coulombic efficiencies of 19.5 and 34.9% in a single chamber fuel cells. Cyclic voltammetry studies showed that anaerobically grown cells of strain KVM11 are electrochemically active whereas aerobically grown cells lacked the electrochemical activity. Electrobioremediation potential of the strain KVM11 was investigated in hydrocarbonoclastic and dye detoxification conditions using MERS. About 89.60% of 400 mg l-1 azo dye was removed during the first 24 h of operation and it reached below detection limits by the end of the batch operation (60 h). Current generation and biodegradation capabilities of strain KVM11 were examined using an initial

Acetate:succinate CoA-transferase in the hydrogenosomes of Trichomonas vaginalis: Identification and characterization

NARCIS (Netherlands)

K.W.A. Grinsven; S. Rosnowsky (Silke); S.W.H. van Weelden (Susanne); S. Pütz (Simone); M. van der Giezen (Mark); W. Martin (William); J.J. van Hellemond (Jaap); A.G.M. Tielens (Aloysius); K. Henze (Katrin)

2008-01-01

textabstractAcetate:succinate CoA-transferases (ASCT) are acetate-producing enzymes in hydrogenosomes, anaerobically functioning mitochondria and in the aerobically functioning mitochondria of trypanosomatids. Although acetate is produced in the hydrogenosomes of a number of anaerobic microbial

Nitrous oxide emission and denitrifier communities in drip-irrigated calcareous soil as affected by chemical and organic fertilizers.

Science.gov (United States)

Tao, Rui; Wakelin, Steven A; Liang, Yongchao; Hu, Baowei; Chu, Guixin

2018-01-15

The effects of consecutive application of chemical fertilizer with or without organic fertilizer on soil N 2 O emissions and denitrifying community structure in a drip-irrigated field were determined. The four fertilizer treatments were (i) unfertilized, (ii) chemical fertilizer, (iii) 60% chemical fertilizer plus cattle manure, and (iv) 60% chemical fertilizer plus biofertilizer. The treatments with organic amendments (i.e. cattle manure and biofertilizer) reduced cumulative N 2 O emissions by 4.9-9.9%, reduced the N 2 O emission factor by 1.3-42%, and increased denitrifying enzyme activities by 14.3-56.2%. The nirK gene copy numbers were greatest in soil which received only chemical fertilizer. In contrast, nirS- and nosZ-copy numbers were greatest in soil amended with chemical fertilizer plus biofertilizer. Chemical fertilizer application with or without organic fertilizer significantly changed the community structure of nirK-type denitrifiers relative to the unfertilized soil. In comparison, the nirS- and nosZ-type denitrifier genotypes varied in treatments receiving organic fertilizer but not chemical fertilizer alone. The changes in the denitrifier communities were closely associated with soil organic carbon (SOC), NO 3 - , NH 4 + , water holding capacity, and soil pH. Modeling indicated that N 2 O emissions in this soil were primarily associated with the abundance of nirS type denitrifying bacteria, SOC, and NO 3 - . Overall, our findings indicate that (i) the organic fertilizers increased denitrifying enzyme activity, increased denitrifying-bacteria gene copy numbers, but reduced N 2 O emissions, and (ii) nirS- and nosZ-type denitrifiers were more sensitive than nirK-type denitrifiers to the organic fertilizers. Copyright © 2017. Published by Elsevier B.V.

Relative Contribution of nirK- and nirS- Bacterial Denitrifiers as Well as Fungal Denitrifiers to Nitrous Oxide Production from Dairy Manure Compost.

Science.gov (United States)

Maeda, Koki; Toyoda, Sakae; Philippot, Laurent; Hattori, Shohei; Nakajima, Keiichi; Ito, Yumi; Yoshida, Naohiro

2017-12-19

The relative contribution of fungi, bacteria, and nirS and nirK denirifiers to nitrous oxide (N 2 O) emission with unknown isotopic signature from dairy manure compost was examined by selective inhibition techniques. Chloramphenicol (CHP), cycloheximide (CYH), and diethyl dithiocarbamate (DDTC) were used to suppress the activity of bacteria, fungi, and nirK-possessing denitrifiers, respectively. Produced N 2 O were surveyed to isotopocule analysis, and its 15 N site preference (SP) and δ 18 O values were compared. Bacteria, fungi, nirS, and nirK gene abundances were compared by qPCR. The results showed that N 2 O production was strongly inhibited by CHP addition in surface pile samples (82.2%) as well as in nitrite-amended core samples (98.4%), while CYH addition did not inhibit the N 2 O production. N 2 O with unknown isotopic signature (SP = 15.3-16.2‰), accompanied by δ 18 O (19.0-26.8‰) values which were close to bacterial denitrification, was also suppressed by CHP and DDTC addition (95.3%) indicating that nirK denitrifiers were responsible for this N 2 O production despite being less abundant than nirS denitrifiers. Altogether, our results suggest that bacteria are important for N 2 O production with different SP values both from compost surface and pile core. However, further work is required to decipher whether N 2 O with unknown isotopic signature is mostly due to nirK denitrifiers that are taxonomically different from the SP-characterized strains and therefore have different SP values rather than also being interwoven with the contribution of the NO-detoxifying pathway and/or of co-denitrification.

Anomalous electrical signals associated with microbial activity: Results from Iron and Nitrate-Reducing Columns

Science.gov (United States)

Aaron, R. B.; Zheng, Q.; Flynn, P.; Singha, K.; Brantley, S.

2008-12-01

Three flow-through columns outfitted with Ag/AgCl electrodes were constructed to test the effects of different microbial processes on the geophysical measurements of self potential (SP), bulk electrical conductivity (σ b), and induced polarization (IP). The columns were filled with sieved, Fe-bearing subsurface sediment from the Delmarva Peninsula near Oyster, VA, inoculated (9:1 ratio) with a freshly-collected, shallow subsurface sediment from a wetland floodplain (Dorn Creek) near Madison, WI. Each of the columns was fed anoxic and sterile PIPES buffered artificial groundwater (PBAGW) containing different concentrations of acetate and nitrate. The medium fed to Column 1 (nitrate-reducing) was amended with 100 μM acetate and 2 mM nitrate. Column 2 (iron-reducing) was run with PBAGW containing 1.0 mM acetate and 0 mM nitrate. Column 3 (alternating redox state) was operated under conditions designed to alternately stimulate nitrate-reducing and iron-reducing populations to provide conditions, i.e., the presence of both nitrate and microbially-produced Fe(II), that would allow growth of nitrate-dependent Fe(II)-oxidizing populations. We operated Column 3 with a cycling strategy of 14-18 days of high C medium (1 mM acetate and 100 μ M nitrate) followed by 14-18 days of low C medium (100 μ M acetate and 2 mM nitrate). Effluent chemistry (NO3-, NO2-, NH4+, acetate, and Fe2+) was sampled daily for four months so as to be concurrent with the electrical measurements. We observed chemical evidence of iron reduction (dissolved [Fe(II)] = 0.2mM) in the effluent from the iron reduction and alternating redox columns. Chemical depletion of NO3- ([NO3-] ranged from 1 to 0.02mM), the production of NO2-, and possible production of NH4+ (0.2 mM) was observed in the nitrate reducing column as well as the alternating redox column. All three columns displayed loss of acetate as microbial activity progressed. σ b remained constant in the alternating redox column (~0.15 S

Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

Science.gov (United States)

Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

2015-11-01

Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electricity-Assisted Biological Hydrogen Production from Acetate by Geobacter sulfurreducens

NARCIS (Netherlands)

Geelhoed, J.S.; Stams, A.J.M.

2011-01-01

Geobacter sulfurreducens is a well-known current-producing microorganism in microbial fuel cells, and is able to use acetate and hydrogen as electron donor. We studied the functionality of G. sulfurreducens as biocatalyst for hydrogen formation at the cathode of a microbial electrolysis cell (MEC).

Biosynthesis of Citric Acid from Glycerol by Acetate Mutants of Yarrowia lipolytica in Fed-Batch Fermentation

Directory of Open Access Journals (Sweden)

Anita Rywińska

2009-01-01

Full Text Available Pure and crude glycerol from biodiesel production have been used as substrates for citric acid production by acetate-negative mutants of Yarrowia lipolytica in fed-batch fermentation. Both the final concentration and the yield of the product were the highest when Y. lipolytica Wratislavia AWG7 strain was used in the culture with pure or crude glycerol. With a medium containing 200 g/L of glycerol, production reached a maximum of citric acid of 139 g/L after 120 h. This high yield of the product (up to 0.69 g of citric acid per gram of glycerol consumed was achieved with both pure and crude glycerol. Lower yield of citric acid in the culture with Y. lipolytica Wratislavia K1 strain (about 0.45 g/g resulted from increased erythritol concentrations (up to 40 g/L, accumulated simultaneously with the citric acid. The concentration of isocitric acid, a by-product in this fermentation, was very low, in the range from 2.6 to 4.6 g/L.

Relating groundwater and sediment chemistry to microbial characterization at a BTEX-contaminated site

International Nuclear Information System (INIS)

Pfiffner, S.M.; Palumbo, A.V.; McCarthy, J.F.; Gibson, T.

1996-01-01

The National Center for Manufacturing Science is investigating bioremediation of petroleum hydrocarbon at a site in Belleville, Michigan. As part of this study we examined the microbial communities to help elucidate biodegradative processes currently active at the site. We observed high densities of aerobic hydrocarbon degraders and denitrifiers in the less-contaminated sediments. Low densities of iron and sulfate reducers were measured in the same sediments. In contrast, the highly-contaminated sediments showed low densities of aerobic hydrocarbon degraders and denitrifiers and high densities of iron and sulfate reducers. Methanogens were also found in these highly-contaminated sediments. These contaminated sediments also showed a higher biomass, by phospholipid fatty acids, and greater ratios of phospholipid fatty acids which indicate stress within the microbial community. Aquifer chemistry analyses indicated that the more-contaminated area was more reduced and had lower sulfate than the less-contaminated area. These conditions suggest that the subsurface environment at the highly-contaminated area had progressed into sulfate reduction and methanogensis. The less-contaminated area, although less reduced, also appeared to be progressing into primarily iron- and sulfate-reducing microbial communities. The proposed treatment to stimulate bioremediation includes addition of oxygen and nitrate. Groundwater chemistry and microbial analyses revealed significant differences resulted from the injection of dissolved oxygen and nitrate in the subsurface. These differences included increases in pH and Eh and large decreases in BTEX, dissolved iron, and sulfate concentrations at the injection well

Analysis of denitrifier community in a bioaugmented sequencing batch reactor for the treatment of coking wastewater containing pyridine and quinoline

Energy Technology Data Exchange (ETDEWEB)

Bai, Yaohui; Xing, Rui; Wen, Donghui; Tang, Xiaoyan [Peking Univ., Beijing (CN). Key Lab. of Water and Sediment Sciences (Ministry of Education); Sun, Qinghua [Peking Univ., Beijing (CN). Key Lab. of Water and Sediment Sciences (Ministry of Education); Chinese Center for Disease Control and Prevention, Beijing (China). Inst. of Environmental Health and Related Product Safety

2011-05-15

The denitrifier community and associated nitrate and nitrite reduction in the bioaugmented and general sequencing batch reactors (SBRs) during the treatment of coking wastewater containing pyridine and quinoline were investigated. The efficiency and stability of nitrate and nitrite reduction in SBR was considerably improved after inoculation with four pyridine- or quinoline-degrading bacterial strains (including three denitrifying strains). Terminal restriction fragment length polymorphism (T-RFLP) based on the nosZ gene revealed that the structures of the denitrifier communities in bioaugmented and non-bioaugmented reactors were distinct and varied during the course of the experiment. Bioaugmentation protected indigenous denitrifiers from disruptions caused by pyridine and quinoline. Clone library analysis showed that one of the added denitrifiers comprised approximately 6% of the denitrifier population in the bioaugmented sludge. (orig.)

Effect of -based Direct-fed Microbial on Performance, Nutrient Utilization, Intestinal Morphology and Cecal Microflora in Broiler Chickens

Directory of Open Access Journals (Sweden)

Xinjian Lei

2015-02-01

Full Text Available The present study was conducted to evaluate the effect of the dietary supplementation of Bacillus amyloliquefaciens-based direct-fed microbial (DFM on growth performance, nutrient utilization, intestinal morphology and cecal microflora in broiler chickens. A total of two hundred and eighty eight 1-d-old Arbor Acres male broilers were randomly allocated to one of four experimental treatments in a completely randomized design. Each treatment was fed to eight replicate cages, with nine birds per cage. Dietary treatments were composed of an antibiotic-free basal diet (control, and the basal diet supplemented with either 15 mg/kg of virginiamycin as antibiotic growth promoter (AGP, 30 mg/kg of Bacillus amyloliquefaciens-based DFM (DFM 30 or 60 mg/kg of Bacillus amyloliquefaciens-based DFM (DFM 60. Experimental diets were fed in two phases: starter (d 1 to 21 and finisher (d 22 to 42. Growth performance, nutrient utilization, morphological parameters of the small intestine and cecal microbial populations were measured at the end of the starter (d 21 and finisher (d 42 phases. During the starter phase, DFM and virginiamycin supplementation improved the feed conversion ratio (FCR; p<0.01 compared with the control group. For the finisher phase and the overall experiment (d 1 to 42 broilers fed diets with the DFM had better body weight gain (BWG and FCR than that of control (p<0.05. Supplementation of virginiamycin and DFM significantly increased the total tract apparent digestibility of crude protein (CP, dry matter (DM and gross energy during both starter and finisher phases (p<0.05 compared with the control group. On d 21, villus height, crypt depth and villus height to crypt depth ratio of duodenum, jejunum, and ileum were significantly increased for the birds fed with the DFM diets as compared with the control group (p<0.05. The DFM 30, DFM 60, and AGP groups decreased the Escherichia coli population in cecum at d 21 and d 42 compared with control

Isotope fractionation during the anaerobic consumption of acetate by methanogenic and sulfate-reducing microorganisms

Science.gov (United States)

Gövert, D.; Conrad, R.

2009-04-01

During the anaerobic degradation of organic matter in anoxic sediments and soils acetate is the most important substrate for the final step in production of CO2 and/or CH4. Sulfate-reducing bacteria (SRB) and methane-producing archaea both compete for the available acetate. Knowledge about the fractionation of 13C/12C of acetate carbon by these microbial groups is still limited. Therefore, we determined carbon isotope fractionation in different cultures of acetate-utilizing SRB (Desulfobacter postgatei, D. hydrogenophilus, Desulfobacca acetoxidans) and methanogens (Methanosarcina barkeri, M. acetivorans). Including literature values (e.g., Methanosaeta concilii), isotopic enrichment factors (epsilon) ranged between -35 and +2 permil, possibly involving equilibrium isotope effects besides kinetic isotope effects. The values of epsilon were dependent on the acetate-catabolic pathway of the particular microorganism, the methyl or carboxyl position of acetate, and the relative availability or limitation of the substrate acetate. Patterns of isotope fractionation in anoxic lake sediments and rice field soil seem to reflect the characteristics of the microorganisms actively involved in acetate catabolism. Hence, it might be possible using environmental isotopic information to determine the type of microbial metabolism converting acetate to CO2 and/or CH4.

Effects of porous carrier size on biofilm development, microbial distribution and nitrogen removal in microaerobic bioreactors

KAUST Repository

Ahmad, Muhammad; Liu, Sitong; Mahmood, Nasir; Mahmood, Asif; Ali, Muhammad; Zheng, Maosheng; Ni, Jinren

2017-01-01

In this study, effects of porous carrier’s size (polyurethane-based) on microbial characteristics were systematically investigated in addition to nitrogen removal performance in six microaerobic bioreactors. Among different sized carriers (50, 30, 20, 15,10, 5 mm), 15 mm carrier showed highest nitrogen removal (98%) due to optimal micro-environments created for aerobic nitrifiers in outer layer (0∼7 mm), nitrifiers and denitrifiers in middle layer (7∼10 mm) and anaerobic denitrifiers in inner layer (10∼15 mm). Candidatus brocadia, a dominant anammox bacteria, was solely concentrated close to centroid (0∼70 μm) and strongly co-aggregated with other bacterial communities in the middle layer of the carrier. Contrarily, carriers with a smaller (<15 mm) or larger size (>15 mm) either destroy the effective zone for anaerobic denitrifiers or damage the microaerobic environments due to poor mass transfer. This study is of particular use for optimal design of carriers in enhancing simultaneous nitrification-denitrification in microaerobic wastewater treatment processes.

Effects of porous carrier size on biofilm development, microbial distribution and nitrogen removal in microaerobic bioreactors

KAUST Repository

Ahmad, Muhammad

2017-03-15

In this study, effects of porous carrier’s size (polyurethane-based) on microbial characteristics were systematically investigated in addition to nitrogen removal performance in six microaerobic bioreactors. Among different sized carriers (50, 30, 20, 15,10, 5 mm), 15 mm carrier showed highest nitrogen removal (98%) due to optimal micro-environments created for aerobic nitrifiers in outer layer (0∼7 mm), nitrifiers and denitrifiers in middle layer (7∼10 mm) and anaerobic denitrifiers in inner layer (10∼15 mm). Candidatus brocadia, a dominant anammox bacteria, was solely concentrated close to centroid (0∼70 μm) and strongly co-aggregated with other bacterial communities in the middle layer of the carrier. Contrarily, carriers with a smaller (<15 mm) or larger size (>15 mm) either destroy the effective zone for anaerobic denitrifiers or damage the microaerobic environments due to poor mass transfer. This study is of particular use for optimal design of carriers in enhancing simultaneous nitrification-denitrification in microaerobic wastewater treatment processes.

Mechanisms of nitrous oxide (N2 O) formation and reduction in denitrifying biofilms.

Science.gov (United States)

Sabba, Fabrizio; Picioreanu, Cristian; Nerenberg, Robert

2017-12-01

Nitrous oxide (N 2 O) is a potent greenhouse gas that can be formed in wastewater treatment processes by ammonium oxidizing and denitrifying microorganisms. While N 2 O emissions from suspended growth systems have been extensively studied, and some recent studies have addressed emissions from nitrifying biofilms, much less is known about N 2 O emissions from denitrifying biofilm processes. This research used modeling to evaluate the mechanisms of N 2 O formation and reduction in denitrifying biofilms. The kinetic model included formation and consumption of key denitrification species, including nitrate (NO3-), nitrite (NO2-), nitric oxide (NO), and N 2 O. The model showed that, in presence of excess of electron donor, denitrifying biofilms have two distinct layers of activity: an outer layer where there is net production of N 2 O and an inner layer where there is net consumption. The presence of oxygen (O 2 ) had an important effect on N 2 O emission from suspended growth systems, but a smaller effect on biofilm systems. The effects of NO3- and O 2 differed significantly based on the biofilm thickness. Overall, the effects of biofilm thickness and bulk substrate concentrations on N 2 O emissions are complex and not always intuitive. A key mechanism for denitrifying biofilms is the diffusion of N 2 O and other intermediates from one zone of the biofilm to another. This leads to zones of N 2 O formation or consumption transformations that would not exist in suspended growth systems. © 2017 Wiley Periodicals, Inc.

Effect of two microbial phytase preparations on phosphorus utilisation in broilers fed maize-soybean meal based diets

Directory of Open Access Journals (Sweden)

J. VALAJA

2008-12-01

Full Text Available The present study was carried out to determine the effect of two microbial phytases, Aspergillus niger (FINASEâ FP-500, 291 PU (phytase units/g and Trichoderma reesei phytase (FINASEâ P, 5880 PU/g on phosphorus (P and calcium (Ca utilisation and ileal P and Ca digestibility in broiler chickens fed diets based on maize and soybean meal. A total of 96 Ross broiler chickens housed four birds to a cage were used. Four dietary treatments consisted of a positive control supplemented with dicalcium phosphate (17 g/kg, a negative control without inorganic P, basal diet without inorganic P supplemented with Aspergillus niger phytase (2.6 g/kg and basal diet without inorganic P supplemented with Trichoderma reesei phytase (0.13 g/kg. Both phytases provided 750 PU/kg feed. P retention per unit intake was lowest and P excretion highest in birds fed the positive control diet with inorganic P (P

Effects of the feeding ratio of food waste on fed-batch aerobic composting and its microbial community.

Science.gov (United States)

Wang, Xiaojun; Pan, Songqing; Zhang, Zhaoji; Lin, Xiangyu; Zhang, Yuzhen; Chen, Shaohua

2017-01-01

To determine the suitable feeding ratio for fed-batch aerobic composting, four fermenters were operated by adding 0%, 5%, 10% or 15% of food waste every day. The results showed that the 5% and 10% treatments were able to maintain continuous thermophilic conditions, while the 15% treatment performed badly in regard to composting temperature, which was probably due to the negative effects of excessive moisture on microbial activity. As composting proceeded, both the 5% and the 10% treatments reached maturity and achieved weight losses of approximately 65%. High-throughput sequencing results indicated that Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria were the dominant phyla of the community structure. The communities sampled at the thermophilic phases had high similarity and relatively low diversity, while species diversity increased in the maturity phase. This study was devoted to optimizing the fed-batch composting process and assessing bacterial communities, both of which were supplied as a reference for practical application. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of rumen microbial populations in lactating dairy cattle fed diets varying in carbohydrate profiles and Saccharomyces cerevisiae fermentation product.

Science.gov (United States)

Mullins, C R; Mamedova, L K; Carpenter, A J; Ying, Y; Allen, M S; Yoon, I; Bradford, B J

2013-09-01

The rumen microbial ecosystem is a critical factor that links diets to bovine physiology and productivity; however, information about dietary effects on microbial populations has generally been limited to small numbers of samples and qualitative assessment. To assess whether consistent shifts in microbial populations occur in response to common dietary manipulations in dairy cattle, samples of rumen contents were collected from 2 studies for analysis by quantitative real-time PCR (qPCR). In one study, lactating Holstein cows (n=8) were fed diets in which a nonforage fiber source replaced an increasing proportion of forages and concentrates in a 4×4 Latin square design, and samples of ruminal digesta were collected at 9-h intervals over 3 d at the end of each period. In the second study, lactating Holstein cows (n=15) were fed diets with or without the inclusion of a Saccharomyces cerevisiae fermentation product (SCFP) in a crossover design. In this study, rumen liquid and solid samples were collected during total rumen evacuations before and after feeding in a 42-h period. In total, 146 samples of ruminal digesta were used for microbial DNA isolation and analysis by qPCR. Validated primer sets were used to quantify total bacterial and anaerobic fungal populations as well as 12 well-studied bacterial taxa. The relative abundance of the target populations was similar to those previously reported. No significant treatment effects were observed for any target population. A significant interaction of treatment and dry matter intake was observed, however, for the abundance of Eubacterium ruminantium. Increasing dry matter intake was associated with a quadratic decrease in E. ruminantium populations in control animals but with a quadratic increase in E.ruminantium populations in cows fed SCFP. Analysis of sample time effects revealed that Fibrobacter succinogenes and fungal populations were more abundant postfeeding, whereas Ruminococcus albus tended to be more abundant

Characterization of Microbial Fuel Cells at Microbially and Electrochemically Meaningful Time scales

KAUST Repository

Ren, Zhiyong

2011-03-15

The variable biocatalyst density in a microbial fuel cell (MFC) anode biofilm is a unique feature of MFCs relative to other electrochemical systems, yet performance characterizations of MFCs typically involve analyses at electrochemically relevant time scales that are insufficient to account for these variable biocatalyst effects. This study investigated the electrochemical performance and the development of anode biofilm architecture under different external loadings, with duplicate acetate-fed singlechamber MFCs stabilized at each resistance for microbially relevant time scales. Power density curves from these steady-state reactors generally showed comparable profiles despite the fact that anode biofilm architectures and communities varied considerably, showing that steady-state biofilm differences had little influence on electrochemical performance until the steady-state external loading was much larger than the reactor internal resistance. Filamentous bacteria were dominant on the anodes under high external resistances (1000 and 5000 Ω), while more diverse rod-shaped cells formed dense biofilms under lower resistances (10, 50, and 265 Ω). Anode charge transfer resistance decreased with decreasing fixed external resistances, but was consistently 2 orders of magnitude higher than the resistance at the cathode. Cell counting showed an inverse exponential correlation between cell numbers and external resistances. This direct link ofMFCanode biofilm evolution with external resistance and electricity production offers several operational strategies for system optimization. © 2011 American Chemical Society.

Microbial protein and blood parameters of goats fed with licury cake

Directory of Open Access Journals (Sweden)

Máikal Souza Borja

2014-02-01

Full Text Available The objective of this study was to determine the ideal level of licury cake in the diet of Boer goats through microbial synthesis estimated based on the presence of purine derivatives in the urine and on blood urea and glucose parameters. Twenty uncastrated one-year-old ¾ Boer goats with an average body weight of 18 kg were distributed in a completely randomized design. Each animal was confined to a one m2 suspended stall with access to water ad libitum. The diets were formulated in accordance with the NRC (2007, and the ingredients were: 50% Tifton-85 (Cynodon sp hay, corn meal, soybean meal, premixed vitamin and mineral supplement, and licury cake. The treatments were: 1 0% of the goat’s total diet composed of licury cake (DM basis, 2 15% of the total diet composed of licury cake, 3 30% of the diet composed of licury cake, and 4 45% of the diet composed of licury cake. The experiment lasted for 17 days. The first 10 days were used to adapt the animals to the diets and facilities. The inclusion of the licury cake in the goat’s diets reduced the levels of blood nitrogen and glucose. Urinary excretion decreased linearly with the inclusion of licury cake in the diet. The inclusion of licury cake in the goat’s diets also caused a linear reduction in the excretion of allantoin, xanthine and hypoxanthine and total purine derivative (PD in urine samples. Based on the microbial protein production and blood parameters of goats fed with licury cake, up to 15% of the goat diet may be composed of licury cake.

Efficient simultaneous partial nitrification, anammox and denitrification (SNAD) system equipped with a real-time dissolved oxygen (DO) intelligent control system and microbial community shifts of different substrate concentrations.

Science.gov (United States)

Wen, Xin; Gong, Benzhou; Zhou, Jian; He, Qiang; Qing, Xiaoxia

2017-08-01

Simultaneous partial nitrification, anammox and denitrification (SNAD) process was studied in a sequencing batch biofilm reactor (SBBR) fed with synthetic wastewater in a range of 2200 mgN/L ∼ 50 mgN/L. Important was an external real-time precision dissolved oxygen (DO) intelligent control system that consisted of feed forward control system and feedback control system. This DO control system permitted close control of oxygen supply according to influent concentration, effluent quality and other environmental factors in the reactor. In this study the operation was divided into six phases according to influent nitrogen applied. SNAD system was successfully set up after adding COD into a CANON system. And the presence of COD enabled the survival of denitrifiers, and made Thauera and Pseudomonas predominant as functional denitrifiers in this system. Denaturing gradient gel electrophoresis (DGGE), fluorescence in situ hybridization (FISH) and 16S rRNA amplicon pyrosequencing were used to analyze the microbial variations of different substrate concentrations. Results indicated that the relative population of ammonia oxidizing bacteria (AOB) members decreased when influent ammonia concentration decreased from 2200 mg/L to 50 mg/L, while no dramatic drop of the percent of anammox bacteria was seen. And Nitrosomonas europaea was the predominant AOB in SNAD system treating sewage, while Candidatus Brocadia was the dominant anammox bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

Community structures and activity of denitrifying microbes in a forested catchment in central Japan: survey using nitrite reductase genes

Science.gov (United States)

Ohte, N.; Aoki, M.; Katsuyama, C.; Suwa, Y.; Tange, T.

2012-12-01

To elucidate the mechanisms of denitrification processes in the forested catchment, microbial ecological approaches have been applied in an experimental watershed that has previously investigated its hydrological processes. The study catchment is located in the Chiba prefecture in central Japan under the temperate Asian monsoon climate. Potential activities of denitrification of soil samples were measured by incubation experiments under anoxic condition associated with Na15NO3 addition. Existence and variety of microbes having nitrite reductase genes were investigated by PCR amplification, cloning and sequencings of nirK and nirS fragments after DNA extraction. Contrary to our early expectation that the potential denitrification activity was higher at deeper soil horizon with consistent groundwater residence than that in the surface soil, denitrification potential was higher in shallower soil horizons than deeper soils. This suggested that the deficiency of NO3- as a respiratory substrate for denitrifier occurred in deeper soils especially in the summer. However, high denitrification activity and presence of microbes having nirK and nirS in surface soils usually under aerobic condition was explainable by the fact that the majority of denitrifying bacteria have been recognized as a facultative anaerobic bacterium. This also suggests the possibility of that denitrification occurs even in the surface soils if the wet condition is provided by rainwater during and after a storm event. Community structures of microbes having nirK were different between near surface and deeper soil horizons, and ones having nirS was different between saturated zone (under groundwater table) and unsaturated soil horizons. These imply that microbial communities with nisK are sensitive to the concentration of soil organic matters and ones with nirS is sensitive to soil moisture contents.

Thiosulphate conversion in a methane and acetate fed membrane bioreactor

NARCIS (Netherlands)

Suarez Zuluaga, D.A.; Timmers, P.H.A.; Plugge, C.M.; Stams, A.J.M.; Buisman, C.J.N.; Weijma, J.

2016-01-01

The use of methane and acetate as electron donors for biological reduction of thiosulphate in a 5-L laboratory membrane bioreactor was studied and compared to disproportionation of thiosulphate as competing biological reaction. The reactor was operated for 454 days in semi-batch mode; 30 % of its

Effect of temperature increase from 55 to 65 degrees C on performance and microbial population dynamics of an anaerobic reactor treating cattle manure

DEFF Research Database (Denmark)

Ahring, Birgitte Kiær; Ibrahim, Ashraf; Mladenovska, Zuzana

2001-01-01

C, a decreased activity was found For glucosc-, acetate- , butyrate- and formate-utilizers and no significant activity was measured with propionate. Only the hydrogen-consuming methanogens showed an enhanced activity at 65 degreesC. Numbers of cultivable methanogens, estimated by the most probable number (MPN......The effect of a temperature increase from 55 to 65 degreesC on process performance and microbial population dynamics were investigated in thermophilic, lab-scale, continuously stirred tank reactors. The reactors had a working volume of 3 l and were fed with cattle manure at an organic loading rate....../d at 55 degreesC. Simultaneously, Ibe level of total volatile fatty acids, VFA, increased from being below 0.3g/l to 1.8-2.4g acetate/l. The specific methanogenic activities (SMA) of biomass from the reactors were measured with acetate, propionate, butyrate, hydrogen, formate and glucose. At 65 degrees...

Inhibition of the anaerobic acetate degradation by formate

OpenAIRE

Guyot, Jean-Pierre; Ramirez, F.

1989-01-01

Granular sludge from an UASB reactor fed with VFA showed a very low affinity for formate which provide little support to the theory of interspecies formate transfer. It is shown that formate can inhibit acetate degradation by anaerobic sludge. (Résumé d'auteur)

Thermal pretreatment of the solid fraction of manure: Impact on the biogas reactor performance and microbial community

DEFF Research Database (Denmark)

Mladenovska, Z; Hartmann, H.; Kvist, T.

2006-01-01

Application of thermal treatment at 100-140 degrees C as a pretreatment method prior to anaerobic digestion of a mixture of cattle and swine manure was investigated. In a batch test, biogasification of manure with thermally pretreated solid fraction proceeded faster and resulted in the increase...... of methane yield. The performances of two thermophilic continuously stirred tank reactors (CSTR) treating manure with solid fraction pretreated for 40 minutes at 140 degrees C and non-treated manure were compared. The digester fed with the thermally pretreated manure had a higher methane productivity...... and butyrate - was low. The kinetic parameters of the VFA conversion revealed a reduced affinity of the microbial community from the CSTR fed with thermally pre-treated manure for acetate, propionate and butyrate. The bacterial and archaeal populations identified by t-RLFP analysis of 16S rRNA genes were found...

The Influence of Tallow on Rumen Metabolism, Microbial Biomass Synthesis and Fatty Acid Composition of Bacteria and Protozoa

DEFF Research Database (Denmark)

Weisbjerg, Martin Riis; Børsting, Christian Friis; Hvelplund, Torben

1992-01-01

Rumen metabolism, microbial biomass synthesis and microbial long chain fatty acid composition were studied in lactating cows fed at two levels of dry matter intake (L, 8.6 kg DM and H, 12.6 kg DM) with 0, 4 and 6% added tallow at the low feed level (L0, L4 and L6) and 0, 2, 4 and 6% at the high...... feed level (H0, H2, H4 and H6). Fibre digestibility was not significantly affected by tallow addition. Increasing tallow level in the diet decreased the total VFA concentration, the ratio of acetic acid to propionic acid and the ammonia concentration in the rumen. Crude fat and fatty acid content...... in bacterial and protozoal dry matter increased with increased tallow level, especially due to an increase in fatty acids originating from the feeds. Microbial synthesis in the rumen and flow of amino acids to the duodenum was highest for medium fat intake at the high feed level....

Lambs Fed Fresh Winter Forage Rape (Brassica napus L.) Emit Less Methane than Those Fed Perennial Ryegrass (Lolium perenne L.), and Possible Mechanisms behind the Difference

Science.gov (United States)

Sun, Xuezhao; Henderson, Gemma; Cox, Faith; Molano, German; Harrison, Scott J.; Luo, Dongwen; Janssen, Peter H.; Pacheco, David

2015-01-01

The objectives of this study were to examine long-term effects of feeding forage rape (Brassica napus L.) on methane yields (g methane per kg of feed dry matter intake), and to propose mechanisms that may be responsible for lower emissions from lambs fed forage rape compared to perennial ryegrass (Lolium perenne L.). The lambs were fed fresh winter forage rape or ryegrass as their sole diet for 15 weeks. Methane yields were measured using open circuit respiration chambers, and were 22-30% smaller from forage rape than from ryegrass (averages of 13.6 g versus 19.5 g after 7 weeks, and 17.8 g versus 22.9 g after 15 weeks). The difference therefore persisted consistently for at least 3 months. The smaller methane yields from forage rape were not related to nitrate or sulfate in the feed, which might act as alternative electron acceptors, or to the levels of the potential inhibitors glucosinolates and S-methyl L-cysteine sulfoxide. Ruminal microbial communities in forage rape-fed lambs were different from those in ryegrass-fed lambs, with greater proportions of potentially propionate-forming bacteria, and were consistent with less hydrogen and hence less methane being produced during fermentation. The molar proportions of ruminal acetate were smaller and those of propionate were greater in forage rape-fed lambs, consistent with the larger propionate-forming populations and less hydrogen production. Forage rape contained more readily fermentable carbohydrates and less structural carbohydrates than ryegrass, and was more rapidly degraded in the rumen, which might favour this fermentation profile. The ruminal pH was lower in forage rape-fed lambs, which might inhibit methanogenic activity, shifting the rumen fermentation to more propionate and less hydrogen and methane. The significance of these two mechanisms remains to be investigated. The results suggest that forage rape is a potential methane mitigation tool in pastoral-based sheep production systems. PMID:25803688

Effect of sulfur supplements on cellulolytic rumen micro-organisms and microbial protein synthesis in cattle fed a high fibre diet.

Science.gov (United States)

McSweeney, C S; Denman, S E

2007-11-01

To examine the effect of sulfur-containing compounds on the growth of anaerobic rumen fungi and the fibrolytic rumen bacteria Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes in pure culture and within the cattle rumen. The effect of two reduced sulfur compounds, 3-mercaptopropionic acid (MPA) or 3-mercapto-1-propanesulfonic acid as the sole S source on growth of pure fibroyltic fungal and bacterial cultures showed that these compounds were capable of sustaining growth. An in vivo trial was then conducted to determine the effect of sulfur supplements (MPA and sodium sulfate) on microbial population dynamics in cattle fed the roughage Dichanthium aristatum. Real-time PCR showed significant increases in fibrolytic bacterial and fungal populations when cattle were supplemented with these compounds. Sulfate supplementation leads to an increase in dry matter intake without a change in whole tract dry matter digestibility. Supplementation of low S-containing diets with either sodium sulfate or MPA stimulates microbial growth with an increase in rumen microbial protein supply to the animal. Through the use of real-time PCR monitoring, a better understanding of the effect of S supplementation on discrete microbial populations within the rumen is provided.

Dietary vitamin E (α-tocopheryl acetate) and organic selenium ...

African Journals Online (AJOL)

enriched yeast) and vitamin E (α-tocopheryl acetate) supplementation, alone or together, on the performance and antioxidant status of broilers fed diets enriched in n-3 PUFAs using fish oil. Day-old Hubbard-JV strain broiler chicks allocated to one ...

Quantification of Functional Marker Genes for Denitrifying Microbial Populations in the Chandeleur Islands Impacted by the 2010 Gulf of Mexico Oil Spill

Science.gov (United States)

Crawford, P.; Flournoy, N.; Taylor, C.; Tatariw, C.; Mortazavi, B.; Sobecky, P.

2017-12-01

Barrier island ecosystems provide protection by reducing storm surges, dissipating wave energy, and economically through services such as fisheries, water catchment, and water quality. As these ecosystems are deteriorating and threatened in this century, services provided to humans are being valued monetarily to communicate their importance. Events such as the 2010 Gulf of Mexico oil spill, act as catalysts to accelerate deterioration and further loss of these vital ecosystem services. The oil spill impacted the Chandeleur Islands, barrier islands in Louisiana waters located forty miles south of Gulfport, MS. Island chain vegetation; i.e., Avicennia germinans and native Spartina alterniflora was heavily damaged as a result of the oil spill. As oil was deposited differentially, it was important to investigate the microbiology of oil-impacted areas as marsh vegetation is directly linked to microbe-driven ecosystem services such as denitrification, a nitrogen (N) cycle pathway. The objectives of this study were: i) characterize the biodiversity of microorganisms; ii) quantify denitrifying microbial populations using functional marker genes; and iii) measure rates of denitrification during a one-year period. Eco-functional marker genes narG, nirS, norB, nosZ, and nrfA were selected to represent denitrification. Three different marsh sites were selected for study based upon estimated amounts of prior oiling. Highest rates of denitrification were in September while the lowest rates were observed in February. The highest nirS abundance was detected for two of the three sites (Site 1 and 2) in September while Site 3 exhibited the highest abundance in November. Similarly, the highest abundances observed for norB and nosZ varied by site and by month. Weathered oil was also detected in some of the marsh sediment cores and chemically typed to Macondo oil. Studies such as this one are designed to characterize the barrier island microbial biodiversity and N cycle processes to

Nitrate Removal Rates in Denitrifying Bioreactors During Storm Flows

Science.gov (United States)

Pluer, W.; Walter, T.

2017-12-01

Field denitrifying bioreactors are designed to reduce excess nitrate (NO3-) pollution in runoff from agricultural fields. Field bioreactors saturate organic matter to create conditions that facilitate microbial denitrification. Prior studies using steady flow in lab-scale bioreactors showed that a hydraulic retention time (HRT) between 4 and 10 hours was optimal for reducing NO3- loads. However, during storm-induced events, flow rate and actual HRT fluctuate. These fluctuations have the potential to disrupt the system in significant ways that are not captured by the idealized steady-flow HRT models. The goal of this study was to investigate removal rate during dynamic storm flows of variable rates and durations. Our results indicate that storm peak flow and duration were not significant controlling variables. Instead, we found high correlations (p=0.004) in average removal rates between bioreactors displaying a predominantly uniform flow pattern compared with bioreactors that exhibited preferential flow (24.4 and 21.4 g N m-3 d-1, respectively). This suggests that the internal flow patterns are a more significant driver of removal rate than external factors of the storm hydrograph. Designing for flow patterns in addition to theoretical HRT will facilitate complete mixing within the bioreactors. This will help maximize excess NO3- removal during large storm-induced runoff events.

Influence of a direct-fed microbial and xylanase enzyme on the dietary energy uptake efficiency and performance of broiler chickens.

Science.gov (United States)

Murugesan, Ganapathi Raj; Persia, Michael E

2015-09-01

Efficacy of a multi-strain direct-fed microbial product (PoultryStar(®) ME; PS) and a xylanase enzyme product on the dietary energy utilization efficiency and resulting performance in broiler chickens was evaluated. Apart from performance parameters, cecal and serum metabolites and activities of hepatic enzymes involved in energy metabolism were also determined. Ross 308 chicks were fed one of four experimental diets [control (CON), CON + PS, CON + xylanase and CON + PS + xylanase] using a 2 × 2 factorial arrangement from 1-21 days of age. Cecal proportions of propionate and butyrate, as well as total short-chain fatty acid concentration were increased (P energy uptake and hepatic energy retention. The combination additively increased the FCR, suggesting involvement of synergistic modes of actions. © 2014 Society of Chemical Industry.

Faecal Microbiota of Forage-Fed Horses in New Zealand and the Population Dynamics of Microbial Communities following Dietary Change

Science.gov (United States)

Fernandes, Karlette A.; Kittelmann, Sandra; Rogers, Christopher W.; Gee, Erica K.; Bolwell, Charlotte F.; Bermingham, Emma N.; Thomas, David G.

2014-01-01

The effects of abrupt dietary transition on the faecal microbiota of forage-fed horses over a 3-week period were investigated. Yearling Thoroughbred fillies reared as a cohort were exclusively fed on either an ensiled conserved forage-grain diet (“Group A”; n = 6) or pasture (“Group B”; n = 6) for three weeks prior to the study. After the Day 0 faecal samples were collected, horses of Group A were abruptly transitioned to pasture. Both groups continued to graze similar pasture for three weeks, with faecal samples collected at 4-day intervals. DNA was isolated from the faeces and microbial 16S and 18S rRNA gene amplicons were generated and analysed by pyrosequencing. The faecal bacterial communities of both groups of horses were highly diverse (Simpson’s index of diversity >0.8), with differences between the two groups on Day 0 (Phorses became similar to Group B within four days of feeding on pasture, whereas the structure of the archaeal community remained constant pre- and post-dietary change. The community structure of the faecal microbiota (bacteria, archaea and ciliate protozoa) of pasture-fed horses was also identified. The initial differences observed appeared to be linked to recent dietary history, with the bacterial community of the forage-fed horses responding rapidly to abrupt dietary change. PMID:25383707

Effects of Formic or Acetic Acid on the Storage Quality of Mixed Air-Dried Corn Stover and Cabbage Waste, and Microbial Community Analysis

Directory of Open Access Journals (Sweden)

Cong Wang

2018-01-01

Full Text Available A mixture of air-dried corn stover and cabbage waste was ensiled to preserve lignocellulosic biomass for use as biofuel. Furthermore, the effects of different fresh mass fractions (0.3 and 0.6 % of formic or acetic acid on the mixed silage quality were evaluated to guarantee its quality. The application of formic or acetic acid prior to mixing the silage led to higher water-soluble carbohydrate fractions than the negative control, indicating that both acids contributed to preservation of water-soluble carbohydrates during storage for 170 days. The dry matter content was also increased after storage from 90 to 170 days. It was found that the content of neutral and acid detergent fibre, cellulose and holocellulose (the sum of cellulose and hemicellulose in mixed silage treated with formic or acetic acid was significantly lower than that obtained in the negative control. The pH and the ratio of ammoniacal nitrogen to total nitrogen in mixed silage treated with acetic acid also significantly decreased. Furthermore, the addition of formic or acetic acid significantly weakened the fermentation intensity of lactic acid, depending on the ratio of lactic to acetic acid, as well as the ratio of lactic acid to total organic acids. The number of bacterial species and their relative abundance shifted during silage mixing, wherein microbial communities at phylum level mainly consisted of Proteobacteria and Firmicutes. The dominant bacteria were also observed to shift from Lactobacillus and Enterobacter in presilage biomass to Lactobacillus and Paralactobacillus. Specifically, Enterobacter disappeared after 130 days of storage. In conclusion, the addition of a low dose of acetic acid to fresh mass (0.3 % could effectively improve the fermentation quality and is conducive to the preservation of the organic components.

Insight into the short- and long-term effects of Cu(II) on denitrifying biogranules

International Nuclear Information System (INIS)

Chen, Hui; Chen, Qian-Qian; Jiang, Xiao-Yan; Hu, Hai-Yan; Shi, Man-Ling; Jin, Ren-Cun

2016-01-01

Highlights: • It is the first time to evaluate the effect of Cu"2"+ on denitrifying biogranules. • A high level of Cu(II) was investigated during batch assays and continuous tests. • Mechanisms of the effects of Cu"2"+ on denitrifying biogranules were discussed. • Effects of pre-exposure to Cu"2"+ and starvation treatments were investigated. - Abstract: This study aimed to investigate the short- and long-term effects of Cu"2"+ on the activity and performance of denitrifying bacteria. The short-term effects of various concentrations of Cu"2"+ on the denitrifying bacteria were evaluated using batch assays. The specific denitrifying activity (SDA) decreased from 14.3 ± 2.2 (without Cu"2"+) to 6.1 ± 0.1 mg N h"−"1 g"−"1 VSS (100 mgCu"2"+ L"−"1) when Cu"2"+ increased from 0 to 100 mg L"−"1 with an increment of 10 mgCu"2"+ L"−"1. A non-competitive inhibition model was used to calculate the 50% inhibition concentration (IC_5_0) of Cu"2"+ on denitrifying sludge (30.6 ± 2.5 mg L"−"1). Monod and Luong models were applied to investigate the influence of the initial substrate concentration, and the results suggested that the maximum substrate removal rate would be reduced with Cu"2"+ supplementation. Pre-exposure to Cu"2"+ could lead to an 18.2–46.2% decrease in the SDA and decreasing percentage of the SDA increased with both exposure time and concentration. In the continuous-flow test, Cu"2"+ concentration varied from 1 to 75 mg L"−"1; however, no clear deterioration was observed in the reactor, and the reactor was kept stable, with the total nitrogen removal efficiency and total organic carbon efficiency greater than 89.0 and 85.0%, respectively. The results demonstrated the short-term inhibition of Cu"2"+ upon denitrification, and no notable adversity was observed during the continuous-flow test after long-term acclimation.

Identification of active denitrifiers in full-scale nutrient removal wastewater treatment systems

DEFF Research Database (Denmark)

Mcllroy, Simon; Starnawska, Anna; Starnawski, Piotr

2015-01-01

Denitrification is essential to the removal of nitrogen from wastewater during treatment, yet an understanding of the diversity of the active denitrifying bacteria responsible in full-scale wastewater treatment plants (WWTPs) is lacking. In this study, stable-isotope probing (SIP) was applied......-labelled complex substrate was used for SIP incubations, under nitrite-reducing conditions, in order to maximize the capture of the potentially metabolically diverse denitrifiers likely present. Members of the Rhodoferax, Dechloromonas, Sulfuritalea, Haliangium and Thermomonas were represented in the 16S rRNA gene...

Contribution of above- and below-ground plant traits to the structure and function of grassland soil microbial communities.

Science.gov (United States)

Legay, N; Baxendale, C; Grigulis, K; Krainer, U; Kastl, E; Schloter, M; Bardgett, R D; Arnoldi, C; Bahn, M; Dumont, M; Poly, F; Pommier, T; Clément, J C; Lavorel, S

2014-10-01

Abiotic properties of soil are known to be major drivers of the microbial community within it. Our understanding of how soil microbial properties are related to the functional structure and diversity of plant communities, however, is limited and largely restricted to above-ground plant traits, with the role of below-ground traits being poorly understood. This study investigated the relative contributions of soil abiotic properties and plant traits, both above-ground and below-ground, to variations in microbial processes involved in grassland nitrogen turnover. In mountain grasslands distributed across three European sites, a correlative approach was used to examine the role of a large range of plant functional traits and soil abiotic factors on microbial variables, including gene abundance of nitrifiers and denitrifiers and their potential activities. Direct effects of soil abiotic parameters were found to have the most significant influence on the microbial groups investigated. Indirect pathways via plant functional traits contributed substantially to explaining the relative abundance of fungi and bacteria and gene abundances of the investigated microbial communities, while they explained little of the variance in microbial activities. Gene abundances of nitrifiers and denitrifiers were most strongly related to below-ground plant traits, suggesting that they were the most relevant traits for explaining variation in community structure and abundances of soil microbes involved in nitrification and denitrification. The results suggest that consideration of plant traits, and especially below-ground traits, increases our ability to describe variation in the abundances and the functional characteristics of microbial communities in grassland soils. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Electrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow conditions

KAUST Repository

Ren, Lijiao

2014-07-01

Power production of four hydraulically connected microbial fuel cells (MFCs) was compared with the reactors operated using individual electrical circuits (individual), and when four anodes were wired together and connected to four cathodes all wired together (combined), in fed-batch or continuous flow conditions. Power production under these different conditions could not be made based on a single resistance, but instead required polarization tests to assess individual performance relative to the combined MFCs. Based on the power curves, power produced by the combined MFCs (2.12 ± 0.03 mW, 200 ω) was the same as the summed power (2.13 mW, 50 ω) produced by the four individual reactors in fed-batch mode. With continuous flow through the four MFCs, the maximum power (0.59 ± 0.01 mW) produced by the combined MFCs was slightly lower than the summed maximum power of the four individual reactors (0.68 ± 0.02 mW). There was a small parasitic current flow from adjacent anodes and cathodes, but overall performance was relatively unaffected. These findings demonstrate that optimal power production by reactors hydraulically and electrically connected can be predicted from performance by individual reactors. © 2013 Elsevier B.V. All rights reserved.

Study of charge transfer reactions in a microbial fuel cell

Energy Technology Data Exchange (ETDEWEB)

Martin, E.; Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Dept. de Genie Chimique; National Research Council of Canada, Montreal, PQ (Canada). Biotechnology Research Inst.; Tartakovsky, B. [National Research Council of Canada, Montreal, PQ (Canada). Biotechnology Research Inst.

2008-07-01

Electron transfer reactions in a microbial fuel cell (MFC) were evaluated. The MFC was inoculated with anaerobic mesophilic sludge and operated with carbon felt, carbon cloth, and platinum (Pt) coated carbon cloth. The MFC was then fed with either acetate or glucose as a source of fuel and operated at a temperature of 25 degrees C and a pH of 7. Scanning electron microscopy (SEM) micrographs demonstrated that the micro-organisms colonized the anodes. Cyclic voltammetry and polarization tests were conducted using different fractions of the anodophilic biofilm in order to determine charge transfer routes. The study characterized the electron transfer mechanisms used by the exoelectrogenic micro-organisms to produce electricity. It was concluded that further research is needed to characterize reaction transfer routes. 2 refs., 1 fig.

Invitro Study on the Fluid From Banana Stem Bioprocess as Direct Fed Microbial

Science.gov (United States)

Mutaqin, B. K.; Tanuwiria, U. H.; Hernawan, E.

2018-02-01

The purpose of this research was to study the liquid produced by the bioprocess of banana stem as a Direct Fed Microbial (DFM) in order to enhance local sheep productivity invitro. Studying was the use of DFM in two invitro feeds. The object observed in this research was fermentability and digestibility value. The method was experimental with the experimental design, i.e. factorial experimental design with two factors. The first factor was DFM, the levels of which were 0, 0,2, 0,4 and 0,6%, while the second factor was two feed types (complete feed and Pennisetum purpureum only) with the treatment of threefold repetition. This research showed that fermentability and digestibility value were influenced by the DFM in the invitro complete feed. The research result analyzed using MANOVA with further testing using Duncan Test. The conclusion of the research result were shows the interaction DFM in the complete feed improve fermentability and digestibility values and DFM 0,6% shows the highest value.

Food effect on the bioavailability of two distinct formulations of megestrol acetate oral suspension

Directory of Open Access Journals (Sweden)

Benoit Deschamps

2009-09-01

Full Text Available Benoit Deschamps1, Naomi Musaji2, John A Gillespie21SFBC Anapharm, Montreal, Canada; 2Strativa Pharmaceuticals, a division of Par Pharmaceutical, Inc., Woodcliff Lake, NJ, USAObjective: Megestrol acetate oral suspension (MAOS is an appetite stimulant indicated for cachexia in patients with AIDS. It is available in its original formulation, Megace® (MAOS, and as a nanocrystal dispersion, Megace® ES (MA-ES. Three studies were conducted to evaluate the pharmacokinetic properties of these formulations under fed and fasting conditions.Methods: An open-label, crossover trial was conducted in 24 healthy males randomized to MA-ES 625 mg/5 mL given with a high-calorie, high-fat meal, or after an overnight fast. Blood samples were drawn at multiple time points and pharmacokinetic parameters were determined. Two separate, open-label reference studies evaluated MAOS 800 mg/20 mL in 40 fed or 40 fasting healthy male volunteers.Results: In fasting MA-ES subjects, the average maximum concentration (Cmax was 30% less than the fed Cmax value. For MAOS, fasting Cmax was 86% less than fed Cmax. In fasting subjects, the area under the curve was 12,095 ng⋅h/mL for MA-ES, and 8,942 ng⋅h/mL for MAOS. In fed subjects, the absorption of the two formulations was comparable.Conclusion: Bioavailability and absorption are greater for MA-ES than MAOS in fasting subjects. MA-ES may be a preferred formulation of megestrol acetate when managing cachectic patients whose caloric intake is reduced.Keywords: megestrol acetate, bioavailability, cachexia, nanocrystal technology, appetite stimulant

Effect of ammonium and acetate on methanogenic pathway and methanogenic community composition

DEFF Research Database (Denmark)

Fotidis, Ioannis; Karakashev, Dimitar Borisov; Kotsopoulos, T. A.

2013-01-01

exposure to different ammonia concentrations. The methanogenic pathway was determined by following the production of (14) CH(4) and (14) CO(2) from acetate labeled in the methyl group (C-2). Microbial communities' composition was determined by fluorescence in situ hybridization. Upon acclimatization......Methanogenesis from acetate (aceticlastic methanogenesis or syntrophic acetate oxidation (SAO) coupled with hydrogenotrophic methanogenesis) is the most important step for the biogas process. The major environmental factors influencing methanogenesis are volatile fatty acids, ammonia, p...

Denitrifying woodchip bioreactor and phosphorus filter pairing to minimize pollution swapping.

Science.gov (United States)

Christianson, Laura E; Lepine, Christine; Sibrell, Philip L; Penn, Chad; Summerfelt, Steven T

2017-09-15

Pairing denitrifying woodchip bioreactors and phosphorus-sorbing filters provides a unique, engineered approach for dual nutrient removal from waters impaired with both nitrogen (N) and phosphorus (P). This column study aimed to test placement of two P-filter media (acid mine drainage treatment residuals and steel slag) relative to a denitrifying system to maximize N and P removal and minimize pollution swapping under varying flow conditions (i.e., woodchip column hydraulic retention times (HRTs) of 7.2, 18, and 51 h; P-filter HRTs of 7.6-59 min). Woodchip denitrification columns were placed either upstream or downstream of P-filters filled with either medium. The configuration with woodchip denitrifying systems placed upstream of the P-filters generally provided optimized dissolved P removal efficiencies and removal rates. The P-filters placed upstream of the woodchip columns exhibited better P removal than downstream-placed P-filters only under overly long (i.e., N-limited) retention times when highly reduced effluent exited the woodchip bioreactors. The paired configurations using mine drainage residuals provided significantly greater P removal than the steel slag P-filters (e.g., 25-133 versus 8.8-48 g P removed m -3 filter media d -1 , respectively), but there were no significant differences in N removal between treatments (removal rates: 8.0-18 g N removed m -3 woodchips d -1 ; N removal efficiencies: 18-95% across all HRTs). The range of HRTs tested here resulted in various undesirable pollution swapping by-products from the denitrifying bioreactors: nitrite production when nitrate removal was not complete and sulfate reduction, chemical oxygen demand production and decreased pH during overly long retention times. The downstream P-filter placement provided a polishing step for removal of chemical oxygen demand and nitrite. Copyright © 2017 The Conservation Fund. Published by Elsevier Ltd.. All rights reserved.

Denitrifying woodchip bioreactor and phosphorus filter pairing to minimize pollution swapping

Science.gov (United States)

Christianson, Laura E.; Lepine, Christine; Sibrell, Philip; Penn, Chad J.; Summerfelt, Steven T.

2017-01-01

Pairing denitrifying woodchip bioreactors and phosphorus-sorbing filters provides a unique, engineered approach for dual nutrient removal from waters impaired with both nitrogen (N) and phosphorus (P). This column study aimed to test placement of two P-filter media (acid mine drainage treatment residuals and steel slag) relative to a denitrifying system to maximize N and P removal and minimize pollution swapping under varying flow conditions (i.e., woodchip column hydraulic retention times (HRTs) of 7.2, 18, and 51 h; P-filter HRTs of 7.6–59 min). Woodchip denitrification columns were placed either upstream or downstream of P-filters filled with either medium. The configuration with woodchip denitrifying systems placed upstream of the P-filters generally provided optimized dissolved P removal efficiencies and removal rates. The P-filters placed upstream of the woodchip columns exhibited better P removal than downstream-placed P-filters only under overly long (i.e., N-limited) retention times when highly reduced effluent exited the woodchip bioreactors. The paired configurations using mine drainage residuals provided significantly greater P removal than the steel slag P-filters (e.g., 25–133 versus 8.8–48 g P removed m−3 filter media d−1, respectively), but there were no significant differences in N removal between treatments (removal rates: 8.0–18 g N removed m−3 woodchips d−1; N removal efficiencies: 18–95% across all HRTs). The range of HRTs tested here resulted in various undesirable pollution swapping by-products from the denitrifying bioreactors: nitrite production when nitrate removal was not complete and sulfate reduction, chemical oxygen demand production and decreased pH during overly long retention times. The downstream P-filter placement provided a polishing step for removal of chemical oxygen demand and nitrite.

Characterization of microbial biofilms in a thermophilic biogas system by high-throughput metagenome sequencing.

Science.gov (United States)

Rademacher, Antje; Zakrzewski, Martha; Schlüter, Andreas; Schönberg, Mandy; Szczepanowski, Rafael; Goesmann, Alexander; Pühler, Alfred; Klocke, Michael

2012-03-01

DNAs of two biofilms of a thermophilic two-phase leach-bed biogas reactor fed with rye silage and winter barley straw were sequenced by 454-pyrosequencing technology to assess the biofilm-based microbial community and their genetic potential for anaerobic digestion. The studied biofilms matured on the surface of the substrates in the hydrolysis reactor (HR) and on the packing in the anaerobic filter reactor (AF). The classification of metagenome reads showed Clostridium as most prevalent bacteria in the HR, indicating a predominant role for plant material digestion. Notably, insights into the genetic potential of plant-degrading bacteria were determined as well as further bacterial groups, which may assist Clostridium in carbohydrate degradation. Methanosarcina and Methanothermobacter were determined as most prevalent methanogenic archaea. In consequence, the biofilm-based methanogenesis in this system might be driven by the hydrogenotrophic pathway but also by the aceticlastic methanogenesis depending on metabolite concentrations such as the acetic acid concentration. Moreover, bacteria, which are capable of acetate oxidation in syntrophic interaction with methanogens, were also predicted. Finally, the metagenome analysis unveiled a large number of reads with unidentified microbial origin, indicating that the anaerobic degradation process may also be conducted by up to now unknown species. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Ecological patterns, diversity and core taxa of microbial communities in groundwater-fed rapid gravity filters

DEFF Research Database (Denmark)

Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

2016-01-01

Here, we document microbial communities in rapid gravity filtration units, specifically serial rapid sand filters (RSFs), termed prefilters (PFs) and after- filters (AFs), fed with anoxic groundwaters low in organic carbon to prepare potable waters. A comprehensive 16S rRNA-based amplicon...... sequencing survey revealed a core RSF microbiome comprising few bacterial taxa (29–30 genera) dominated by Nitrospirae, Proteobacteria and Acidobacteria, with a strikingly high abundance (75–87±18%) across five examined waterworks in Denmark. Lineages within the Nitrospira genus consistently comprised...... the second most and most abundant fraction in PFs (27±23%) and AFs (45.2±23%), respectively, and were far more abundant than typical proteobacterial ammonium-oxidizing bacteria, suggesting a physiology beyond nitrite oxidation for Nitrospira. Within the core taxa, sequences closely related to types...

Effect of pH on the denitrifying enzyme activity in pasture soils in relation to the intrinsic differences in denitrifier communities

Czech Academy of Sciences Publication Activity Database

Čuhel, Jiří; Šimek, Miloslav

2011-01-01

Roč. 56, č. 3 (2011), s. 230-235 ISSN 0015-5632 R&D Projects: GA MŠk LC06066; GA AV ČR IAA600660605 Institutional research plan: CEZ:AV0Z60660521 Keywords : pH * denitrifying enzyme activity * pasture soils Subject RIV: EH - Ecology, Behaviour Impact factor: 0.677, year: 2011

Soil properties impacting denitrifier community size, structure, and activity in New Zealand dairy-grazed pasture

Science.gov (United States)

Jha, Neha; Saggar, Surinder; Giltrap, Donna; Tillman, Russ; Deslippe, Julie

2017-09-01

Denitrification is an anaerobic respiration process that is the primary contributor of the nitrous oxide (N2O) produced from grassland soils. Our objective was to gain insight into the relationships between denitrifier community size, structure, and activity for a range of pasture soils. We collected 10 dairy pasture soils with contrasting soil textures, drainage classes, management strategies (effluent irrigation or non-irrigation), and geographic locations in New Zealand, and measured their physicochemical characteristics. We measured denitrifier abundance by quantitative polymerase chain reaction (qPCR) and assessed denitrifier diversity and community structure by terminal restriction fragment length polymorphism (T-RFLP) of the nitrite reductase (nirS, nirK) and N2O reductase (nosZ) genes. We quantified denitrifier enzyme activity (DEA) using an acetylene inhibition technique. We investigated whether varied soil conditions lead to different denitrifier communities in soils, and if so, whether they are associated with different denitrification activities and are likely to generate different N2O emissions. Differences in the physicochemical characteristics of the soils were driven mainly by soil mineralogy and the management practices of the farms. We found that nirS and nirK communities were strongly structured along gradients of soil water and phosphorus (P) contents. By contrast, the size and structure of the nosZ community was unrelated to any of the measured soil characteristics. In soils with high water content, the richnesses and abundances of nirS, nirK, and nosZ genes were all significantly positively correlated with DEA. Our data suggest that management strategies to limit N2O emissions through denitrification are likely to be most important for dairy farms on fertile or allophanic soils during wetter periods. Finally, our data suggest that new techniques that would selectively target nirS denitrifiers may be the most effective for limiting N2O

Continuous power generation and microbial community structure of the anode biofilms in a three-stage microbial fuel cell system

Energy Technology Data Exchange (ETDEWEB)

Chung, Kyungmi; Okabe, Satoshi [Hokkaido Univ., Sapporo (Japan). Dept. of Urban and Environmental Engineering

2009-07-15

A mediator-less three-stage two-chamber microbial fuel cell (MFC) system was developed and operated continuously for more than 1.5 years to evaluate continuous power generation while treating artificial wastewater containing glucose (10 mM) concurrently. A stable power density of 28 W/m3 was attained with an anode hydraulic retention time of 4.5 h and phosphate buffer as the cathode electrolyte. An overall dissolved organic carbon removal ratio was about 85%, and coulombic efficiency was about 46% in this MFC system. We also analyzed the microbial community structure of anode biofilms in each MFC. Since the environment in each MFC was different due to passing on the products to the next MFC in series, the microbial community structure was different accordingly. The anode biofilm in the first MFC consisted mainly of bacteria belonging to the Gammaproteobacteria, identified as Aeromonas sp., while the Firmicutes dominated the anode biofilms in the second and third MFCs that were mainly fed with acetate. Cyclic voltammetric results supported the presence of a redox compound(s) associated with the anode biofilm matrix, rather than mobile (dissolved) forms, which could be responsible for the electron transfer to the anode. Scanning electron microscopy revealed that the anode biofilms were comprised of morphologically different cells that were firmly attached on the anode surface and interconnected each other with anchor-like filamentous appendages, which might support the results of cyclic voltammetry. (orig.)

Enhancing forward osmosis water recovery from landfill leachate by desalinating brine and recovering ammonia in a microbial desalination cell.

Science.gov (United States)

Iskander, Syeed Md; Novak, John T; He, Zhen

2018-05-01

In this work, a microbial desalination cell (MDC) was employed to desalinate the FO treated leachate for reduction of both salinity and chemical oxygen demand (COD). The FO recovered 51.5% water from a raw leachate and the recovery increased to 83.5% from the concentrated leachate after desalination in the MDC fed with either acetate or another leachate as an electron source and at a different hydraulic retention time (HRT). Easily-degraded substrate like acetate and a long HRT resulted in a low conductivity desalinated effluent. Ammonia was also recovered in the MDC cathode with a recovery efficiency varying from 11 to 64%, affected by current generation and HRT. Significant COD reduction, as high as 65.4%, was observed in the desalination chamber and attributed to the decrease of both organic and inorganic compounds via diffusion and electricity-driven movement. Copyright © 2018 Elsevier Ltd. All rights reserved.

Co-composting of municipal solid waste mixed with matured sewage sludge: The relationship between N2O emissions and denitrifying gene abundance.

Science.gov (United States)

Bian, Rongxing; Sun, Yingjie; Li, Weihua; Ma, Qiang; Chai, Xiaoli

2017-12-01

Aerobic composting is an alternative measure to the disposal of municipal solid waste (MSW). However, it produces nitrous oxide (N 2 O), a highly potent greenhouse via microbial nitrification and denitrification. In this study, the effects of matured sewage sludge (MSS) amendment on N 2 O emissions and the inter-relationships between N 2 O emissions and the abundance of denitrifying bacteria were investigated during aerobic composting of MSW. The results demonstrated that MSW composting with MSS amendments (C1, and C2, with a MSW to MSS ratio of 2:1 and 4:1, (v/v), respectively) significantly increased N 2 O emissions during the initial stage, yet contributed to the mitigation of N 2 O emissions during the cooling and maturation stage. MSS amended composting emitted a total of 18.4%-25.7% less N 2 O than the control treatment without MSS amendment (CK). Matured sewage sludge amendment also significantly altered the abundance of denitrifying bacteria. The quantification of denitrifying functional genes revealed that the N 2 O emission rate had a significant positive correlation with the abundance of the nirS, nirK genes in both treatments with MSS amendment. The nosZ/(nirS + nirK) ratio could be a good indicator for predicting N 2 O emissions. The higher N 2 O emission rate during the initial stage of composting mixed with MSS was characterized by lower nosZ/(nirS + nirK) ratios, compared to CK treatment. Higher ratios of nosZ/(nirS + nirK) were measured during the cooling and maturation stage in treatments with MSS which resulted in a reduction of the N 2 O emissions. These results demonstrated that MSS amendment could be a valid strategy for mitigating N 2 O emissions during MSW composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

nirS-type denitrifying bacterial assemblages respond to environmental conditions of a shallow estuary.

Science.gov (United States)

Lisa, Jessica A; Jayakumar, Amal; Ward, Bess B; Song, Bongkeun

2017-12-01

Molecular analysis of dissimilatory nitrite reductase genes (nirS) was conducted using a customized microarray containing 165 nirS probes (archetypes) to identify members of sedimentary denitrifying communities. The goal of this study was to examine denitrifying community responses to changing environmental variables over spatial and temporal scales in the New River Estuary (NRE), NC, USA. Multivariate statistical analyses revealed three denitrifier assemblages and uncovered 'generalist' and 'specialist' archetypes based on the distribution of archetypes within these assemblages. Generalists, archetypes detected in all samples during at least one season, were commonly world-wide found in estuarine and marine ecosystems, comprised 8%-29% of the abundant NRE archetypes. Archetypes found in a particular site, 'specialists', were found to co-vary based on site specific conditions. Archetypes specific to the lower estuary in winter were designated Cluster I and significantly correlated by sediment Chl a and porewater Fe 2+ . A combination of specialist and more widely distributed archetypes formed Clusters II and III, which separated based on salinity and porewater H 2 S respectively. The co-occurrence of archetypes correlated with different environmental conditions highlights the importance of habitat type and niche differentiation among nirS-type denitrifying communities and supports the essential role of individual community members in overall ecosystem function. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Effect of Tree Leaves on Rumen Fermentation, Microbial Count and Blood Urea Nitrogen of West African Dwarf Goats

Directory of Open Access Journals (Sweden)

Adelusi, O. O.

2016-12-01

Full Text Available This experiment was carried out to assess the effect of Azadirachta indica, Newbouldia laevis and Spondias mombin leaves on rumen fermentation, microbial count and blood urea nitrogen (BUN of West African Dwarf (WAD goats. Sixteen WAD bucks (11.6 ? 0.9 kg in body weight were allocated to 4 treatments: 1 Control and 2 40 g/day of Azadirachta indica, 3 40 g/day of Newbouldia laevis and 4 40 g/day of Spondias mombin leaves arranged in a completely randomised design. The ground leaves were included in concentrate diets served on dry matter basis at 2% of body weight while Panicum maximum was fed ad libitum. The control diet had no tree leaves. Data were collected on chemical composition, rumen fermentation and microbial ecology, and BUN. Saponin was highest (P < 0.05 in S. mombin (8.14% while A. indica and N. laevis had 5.78% and 1.56%, respectively. Rumen ammonia nitrogen was least (P < 0.05 in goats fed A. indica (8.35 mg/dL while the highest (P < 0.05 total volatile fatty acid (TVFA was obtained from goats fed S. mombin with 125.51 mM. Goats fed N. laevis yielded the highest (P < 0.05 acetate with 70.65 mol/100 mol while propionate production was highest (P < 0.05 in the rumen of goats fed S. mombin (27.15 mol/100 mol. Viable bacteria count was lowest (P < 0.05 in rumen of goats fed A. indica (3.95?1012 cfu/ml while the least (P < 0.05 protozoa population was obtained from the rumen of bucks fed S. mombin (4.18?109 cfu/ml. All goats in the treatments containing tree leaves had higher (P < 0.05 and a rapid increase in BUN between 0 and 6 h post feeding when compared with the Control. It is concluded that feeding ground leaves of S. mombin to goats increases rumen total volatile fatty acid and propionate production and reduces the protozoa population.

Effect of Saccharomyces cerevisiae on alfalfa nutrient degradation characteristics and rumen microbial populations of steers fed diets with different concentrate-to-forage ratios.

Science.gov (United States)

Ding, Gengzhi; Chang, Ying; Zhao, Liping; Zhou, Zhenming; Ren, Liping; Meng, Qingxiang

2014-01-01

Live yeast (Saccharomyces cerevisiae) constitutes an effective additive for animal production; its probiotic effect may be related to the concentrate-to-forage ratio (CTFR). The objective of this study was to assess the effects of S. cerevisiae (SC) on fiber degradation and rumen microbial populations in steers fed diets with different levels of dietary concentrate. Ten Simmental × Local crossbred steers (450 ± 50 kg BW) were assigned to a control group or an SC group. Both groups were fed the same basal diet but the SC group received SC supplementation (8 × 10(9) cfu/h/d through the ruminal fistula) following a two-period crossover design. Each period consisted of four phases, each of which lasted 17 d: 10 d for dietary adaptation, 6 d for degradation study, and 1 d for rumen sample collection. From the 1(st) to the 4(th) phase, steers were fed in a stepwise fashion with increasing CTFRs, i.e., 30:70, 50:50, 70:30, and 90:10. The kinetics of dry matter and fiber degradation of alfalfa pellets were evaluated; the rumen microbial populations were detected using real-time PCR. The results revealed no significant (P > 0.05) interactions between dietary CTFR and SC for most parameters. Dietary CTFR had a significant effect (P trend for these parameters. SC supplementation significantly (P trend of rumen fungi and protozoa in SC group (P < 0.1); copies of total bacteria in SC group were significantly higher (P < 0.05). Additionally, percentage of Ruminobacter amylophilus was significantly lower (P < 0.05) but percentage of Selenomonas ruminantium was significantly higher (P < 0.05) in the SC group. In a word, dietary CTFR had a significant effect on degradation characteristics of forage and rumen microbial population. S. cerevisiae had positive effects on DM and NDF degradation rate or effective degradability of forage; S. cerevisiae increased rumen total bacteria, fungi, protozoa, and lactate-utilizing bacteria but reduced

Performance of broiler chicken fed varied nutrient density diets supplemented with direct fed microbial

Directory of Open Access Journals (Sweden)

Katoch S.

2013-01-01

Full Text Available Comparative dietary response of different isolated strains (Direct fed microbial- DFM of lactobacilli, streptococci and yeast isolated from leopard feces (Panthera leo was studied as probiotic in poultry broiler birds reared as per varied mineral densities viz. calcium and phosphorus. Various treatments consisted of T0 (Control, culture medium, T1 (Lactobacillus casei + Streptococcus fecalis + Saccharomyces cerevisiae offered standard formulated diet D1, T2 - Control (Culture medium offered ten percent lower calcium and phosphorus diet D2, T3 (Lactobacillus casei + Streptococcus fecalis + Saccharomyces cerevisiae offered ten percent lower calcium and phosphorus diet D2. Growth results obtained during the starter phase (1st to 3rd week exhibited higher gain in live body weight and lower feed conversion ratio, both by DFM supplemented treatment T1 offered standard formulated diet D1 and treatment T3 offered experimentally formulated mineral (Ca and P deficient (10% diet D2 compared to respective control T0 and T2. The obtained results revealed a significantly higher growth performance in treatment T1 compared to its control T0 where a higher growth in treatment T3 offered experimentally formulated mineral (Ca and P deficient (10% diet D2 supplemented with isolated DFM compared to its control T2 was exhibited. Treatment groups T1 and T3 supplemented with isolated DFM exhibited a better intestinal micro flora balance, effective colonization and higher count in the intestinal tract with higher calcium and phosphorus retention in the digestibility studies. Thus, it was found that supplementation of isolated DFM has the potential to improve biological growth performance of poultry broiler birds offered both standard formulated diet D1, as well as mineral deficient diet D2. [Projekat Ministarstva nauke Republike Srbije, br. III 46002

Controlling Salmonella infection in weanling pigs through water delivery of direct-fed microbials or organic acids: Part II. Effects on intestinal histology and active nutrient transport

Science.gov (United States)

The objective of this study was to evaluate the effects of water-delivered direct-fed microbials (DFM) or organic acids on intestinal morphology and active nutrient absorption in weanling pigs following deliberate Salmonella infection. Pigs (n = 88) were weaned at 19 ± 2 d of age and assigned to one...

Microbial Protein Production and Nitrogen Balance of Local Steer Fed Ammoniated Rice Straws Added

Directory of Open Access Journals (Sweden)

H Hindratiningrum

2009-05-01

Full Text Available The objective of the experiment was to investigate the kind of energy source feedstuffs on nutrient balance and microbial protein synthesis in local male beef cattle fed with ammoniated rice straws Twenty steers Peranakan Ongole (PO with average age 1-2 years old were used. They were divided 5 groups based on initial body weight as block. Therefore, Completely Randomised Block Design (CBRD was used for this experiment. Data were analysed by analysis variance and continued honestly significant different (HSD to test the differences between means. The result showed that the range MCP and eficiency MCP were 154,61 g/d until 226,54 g/d and 54,08 gMCP/kg DOMR until 62,64 gMCP/kg DOMR. The range of nitrogen balance were 72,28 gram until 111,67 gram. MCP and efficiency MCP were not affected (P>0,05 by the treatments but balance of nitrogen was affected (P<0,05. Diet containing fresh cassava waste as energy source (R2 was lower (P<0,05 than R1 and R4 while between R1,R3 and R4 was similar. This results indicate that feed source of energy (rice brand, wet cassava waste, dry cassava waste and corn can be used in steers with rice straw ensilage as forage. (Animal Production 11(2: 116-121 (2009 Key Words : Microbial protein production, nitrogen balance, rice straw, ensilage

Non-catalyzed cathodic oxygen reduction at graphite granules in microbial fuel cells

International Nuclear Information System (INIS)

Freguia, Stefano; Rabaey, Korneel; Yuan Zhiguo; Keller, Juerg

2007-01-01

Oxygen is the most sustainable electron acceptor currently available for microbial fuel cell (MFC) cathodes. However, its high overpotential for reduction to water limits the current that can be produced. Several materials and catalysts have previously been investigated in order to facilitate oxygen reduction at the cathode surface. This study shows that significant stable currents can be delivered by using a non-catalyzed cathode made of granular graphite. Power outputs up to 21 W m -3 (cathode total volume) or 50 W m -3 (cathode liquid volume) were attained in a continuous MFC fed with acetate. These values are higher than those obtained in several other studies using catalyzed graphite in various forms. The presence of nanoscale pores on granular graphite provides a high surface area for oxygen reduction. The current generated with this cathode can sustain an anodic volume specific COD removal rate of 1.46 kg COD m -3 d -1 , which is higher than that of a conventional aerobic process. This study demonstrates that microbial fuel cells can be operated efficiently using high surface graphite as cathode material. This implies that research on microbial fuel cell cathodes should not only focus on catalysts, but also on high surface area materials

Non-catalyzed cathodic oxygen reduction at graphite granules in microbial fuel cells

Energy Technology Data Exchange (ETDEWEB)

Freguia, Stefano; Rabaey, Korneel; Yuan, Zhiguo; Keller, Juerg [The University of Queensland, St. Lucia, Qld (Australia). Advanced Wastewater Management Centre

2007-12-01

Oxygen is the most sustainable electron acceptor currently available for microbial fuel cell (MFC) cathodes. However, its high overpotential for reduction to water limits the current that can be produced. Several materials and catalysts have previously been investigated in order to facilitate oxygen reduction at the cathode surface. This study shows that significant stable currents can be delivered by using a non-catalyzed cathode made of granular graphite. Power outputs up to 21 W m{sup -3} (cathode total volume) or 50 W m{sup -3} (cathode liquid volume) were attained in a continuous MFC fed with acetate. These values are higher than those obtained in several other studies using catalyzed graphite in various forms. The presence of nanoscale pores on granular graphite provides a high surface area for oxygen reduction. The current generated with this cathode can sustain an anodic volume specific COD removal rate of 1.46 kg{sub COD} m{sup -3} d{sup -1}, which is higher than that of a conventional aerobic process. This study demonstrates that microbial fuel cells can be operated efficiently using high surface graphite as cathode material. This implies that research on microbial fuel cell cathodes should not only focus on catalysts, but also on high surface area materials. (author)

Faecal microbiota of forage-fed horses in New Zealand and the population dynamics of microbial communities following dietary change.

Science.gov (United States)

Fernandes, Karlette A; Kittelmann, Sandra; Rogers, Christopher W; Gee, Erica K; Bolwell, Charlotte F; Bermingham, Emma N; Thomas, David G

2014-01-01

The effects of abrupt dietary transition on the faecal microbiota of forage-fed horses over a 3-week period were investigated. Yearling Thoroughbred fillies reared as a cohort were exclusively fed on either an ensiled conserved forage-grain diet ("Group A"; n = 6) or pasture ("Group B"; n = 6) for three weeks prior to the study. After the Day 0 faecal samples were collected, horses of Group A were abruptly transitioned to pasture. Both groups continued to graze similar pasture for three weeks, with faecal samples collected at 4-day intervals. DNA was isolated from the faeces and microbial 16S and 18S rRNA gene amplicons were generated and analysed by pyrosequencing. The faecal bacterial communities of both groups of horses were highly diverse (Simpson's index of diversity > 0.8), with differences between the two groups on Day 0 (P 003), CF231 (family Paraprevotellaceae; P = 0.004), and currently unclassified members within the order Clostridiales (P = 0.003) and within the family Lachnospiraceae (P = 0.006). The bacterial community of Group A horses became similar to Group B within four days of feeding on pasture, whereas the structure of the archaeal community remained constant pre- and post-dietary change. The community structure of the faecal microbiota (bacteria, archaea and ciliate protozoa) of pasture-fed horses was also identified. The initial differences observed appeared to be linked to recent dietary history, with the bacterial community of the forage-fed horses responding rapidly to abrupt dietary change.

Salinity shifts in marine sediment: Importance of number of fluctuation rather than their intensities on bacterial denitrifying community.

Science.gov (United States)

Zaghmouri, Imen; Michotey, Valerie D; Armougom, Fabrice; Guasco, Sophie; Bonin, Patricia C

2018-05-01

The sensitivity of denitrifying community to salinity fluctuations was studied in microcosms filled with marine coastal sediments subjected to different salinity disturbances over time (sediment under frequent salinity changes vs sediment with "stable" salinity pattern). Upon short-term salinity shift, denitrification rate and denitrifiers abundance showed high resistance whatever the sediment origin is. Denitrifying community adapted to frequent salinity changes showed high resistance when salinity increases, with a dynamic nosZ relative expression level. Marine sediment denitrifying community, characterized by more stable pattern, was less resistant when salinity decreases. However, after two successive variations of salinity, it shifted toward the characteristic community of fluctuating conditions, with larger proportion of Pseudomonas-nosZ, exhibiting an increase of nosZ relative expression level. The impact of long-term salinity variation upon bacterial community was confirmed at ribosomal level with a higher percentage of Pseudomonas and lower proportion of nosZII clade genera. Copyright © 2018 Elsevier Ltd. All rights reserved.

Microbial populations and activities of mangrove, restinga and Atlantic forest soils from Cardoso Island, Brazil.

Science.gov (United States)

Pupin, B; Nahas, E

2014-04-01

Mangroves provide a distinctive ecological environment that differentiates them from other ecosystems. This study deal to evaluate the frequency of microbial groups and the metabolic activities of bacteria and fungi isolated from mangrove, restinga and Atlantic forest soils. Soil samples were collected during the summer and winter at depths of 0-2, 2-5 and 5-10 cm. Except for fungi, the counts of the total, sporulating, Gram-negative, actinomycetes, nitrifying and denitrifying bacteria decreased significantly in the following order: Atlantic forest >mangrove > restinga. The counts of micro-organisms decreased by 11 and 21% from the surface to the 2-5 and 5-10 cm layers, but denitrifying bacteria increased by 44 and 166%, respectively. A larger growth of micro-organisms was verified in the summer compared with the winter, except for actinomycetes and fungi. The average frequency of bacteria isolated from mangrove, restinga and Atlantic forest soils was 95, 77 and 78%, and 93, 90 and 95% for fungi, respectively. Bacteria were amylolytic (33%), producers of acid phosphatase (79%) and solubilizers (18%) of inorganic phosphate. The proportions of fungi were 19, 90 and 27%. The mangrove soil studied had higher chemical characteristics than the Atlantic forest, but the high salinity may have restricted the growth of microbial populations. Estimates of the microbial counts and activities were important to elucidate the differences of mangrove ecosystem from restinga and Atlantic forest. © 2013 The Society for Applied Microbiology.

Abundance and Diversity of Denitrifying and Anammox Bacteria in Seasonally Hypoxic and Sulfidic Sediments of the Saline Lake Grevelingen

NARCIS (Netherlands)

Lipsewers, Y.A.; Hopmans, E.C.; Meysman, F.J.R.; Sinninghe Damsté, J.S.; Villanueva, L.

2016-01-01

Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox,

Abundance and diversity of denitrifying and anammox bacteria in seasonally hypoxic and sulfidic sediments of the saline lake grevelingen

NARCIS (Netherlands)

Lipsewers, Yvonne A.; Hopmans, Ellen C.; Meysman, Filip J.R.; Sinninghe Damsté, Jaap S.|info:eu-repo/dai/nl/07401370X; Villanueva, Laura

2016-01-01

Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox,

Identification and activity of acetate-assimilating bacteria in diffuse fluids venting from two deep-sea hydrothermal systems.

Science.gov (United States)

Winkel, Matthias; Pjevac, Petra; Kleiner, Manuel; Littmann, Sten; Meyerdierks, Anke; Amann, Rudolf; Mußmann, Marc

2014-12-01

Diffuse hydrothermal fluids often contain organic compounds such as hydrocarbons, lipids, and organic acids. Microorganisms consuming these compounds at hydrothermal sites are so far only known from cultivation-dependent studies. To identify potential heterotrophs without prior cultivation, we combined microbial community analysis with short-term incubations using (13)C-labeled acetate at two distinct hydrothermal systems. We followed cell growth and assimilation of (13)C into single cells by nanoSIMS combined with fluorescence in situ hybridization (FISH). In 55 °C-fluids from the Menez Gwen hydrothermal system/Mid-Atlantic Ridge, a novel epsilonproteobacterial group accounted for nearly all assimilation of acetate, representing the first aerobic acetate-consuming member of the Nautiliales. In contrast, Gammaproteobacteria dominated the (13) C-acetate assimilation in incubations of 37 °C-fluids from the back-arc hydrothermal system in the Manus Basin/Papua New Guinea. Here, 16S rRNA gene sequences were mostly related to mesophilic Marinobacter, reflecting the high content of seawater in these fluids. The rapid growth of microorganisms upon acetate addition suggests that acetate consumers in diffuse fluids are copiotrophic opportunists, which quickly exploit their energy sources, whenever available under the spatially and temporally highly fluctuating conditions. Our data provide first insights into the heterotrophic microbial community, catalyzing an under-investigated part of microbial carbon cycling at hydrothermal vents. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Post-cold-storage conditioning time affects soil denitrifying enzyme activity

DEFF Research Database (Denmark)

Chirinda, Ngonidzashe; Olesen, Jørgen Eivind; Porter, John Roy

2011-01-01

Soil denitrifying enzyme activity (DEA) is often assessed after cold storage. Previous studies using the short-term acetylene inhibition method have not considered conditioning time (post-cold-storage warm-up time prior to soil analysis) as a factor influencing results. We observed fluctuations...

Recipient-Biased Competition for an Intracellularly Generated Cross-Fed Nutrient Is Required for Coexistence of Microbial Mutualists.

Science.gov (United States)

McCully, Alexandra L; LaSarre, Breah; McKinlay, James B

2017-11-28

Many mutualistic microbial relationships are based on nutrient cross-feeding. Traditionally, cross-feeding is viewed as being unidirectional, from the producer to the recipient. This is likely true when a producer's waste, such as a fermentation product, has value only for a recipient. However, in some cases the cross-fed nutrient holds value for both the producer and the recipient. In such cases, there is potential for nutrient reacquisition by producer cells in a population, leading to competition against recipients. Here, we investigated the consequences of interpartner competition for cross-fed nutrients on mutualism dynamics by using an anaerobic coculture pairing fermentative Escherichia coli and phototrophic Rhodopseudomonas palustris In this coculture, E. coli excretes waste organic acids that provide a carbon source for R. palustris In return, R. palustris cross-feeds E. coli ammonium (NH 4 + ), a compound that both species value. To explore the potential for interpartner competition, we first used a kinetic model to simulate cocultures with varied affinities for NH 4 + in each species. The model predicted that interpartner competition for NH 4 + could profoundly impact population dynamics. We then experimentally tested the predictions by culturing mutants lacking NH 4 + transporters in both NH 4 + competition assays and mutualistic cocultures. Both theoretical and experimental results indicated that the recipient must have a competitive advantage in acquiring cross-fed NH 4 + to sustain the mutualism. This recipient-biased competitive advantage is predicted to be crucial, particularly when the communally valuable nutrient is generated intracellularly. Thus, the very metabolites that form the basis for mutualistic cross-feeding can also be subject to competition between mutualistic partners. IMPORTANCE Mutualistic relationships, particularly those based on nutrient cross-feeding, promote stability of diverse ecosystems and drive global biogeochemical

Fermentative Bacteria Influence the Competition between Denitrifiers and DNRA Bacteria

Directory of Open Access Journals (Sweden)

Eveline M. van den Berg

2017-09-01

Full Text Available Denitrification and dissimilatory reduction to ammonium (DNRA are competing nitrate-reduction processes that entail important biogeochemical consequences for nitrogen retention/removal in natural and man-made ecosystems. The nature of the available carbon source and electron donor have been suggested to play an important role on the outcome of this microbial competition. In this study, the influence of lactate as fermentable carbon source on the competition for nitrate was investigated for varying ratios of lactate and nitrate in the influent (Lac/N ratio. The study was conducted in an open chemostat culture, enriched from activated sludge, under strict anoxia. The mechanistic explanation of the conversions observed was based on integration of results from specific batch tests with biomass from the chemostat, molecular analysis of the biomass enriched, and a computational model. At high Lac/N ratio (2.97 mol/mol both fermentative and respiratory nitrate reduction to ammonium occurred, coupled to partial oxidation of lactate to acetate, and to acetate oxidation respectively. Remaining lactate was fermented to propionate and acetate. At a decreased Lac/N ratio (1.15 mol/mol, the molar percentage of nitrate reduced to ammonium decreased to 58%, even though lactate was supplied in adequate amounts for full ammonification and nitrate remained the growth limiting compound. Data evaluation at this Lac/N ratio suggested conversions were comparable to the higher Lac/N ratio, except for lactate oxidation to acetate that was coupled to denitrification instead of ammonification. Respiratory DNRA on acetate was likely catalyzed by two Geobacter species related to G. luticola and G. lovleyi. Two Clostridiales members were likely responsible for lactate fermentation and partial lactate fermentation to acetate coupled to fermentative DNRA. An organism related to Propionivibrio militaris was identified as the organism likely responsible for denitrification. The

Differences in microbial community structure and nitrogen cycling in natural and drained tropical peatland soils.

Science.gov (United States)

Espenberg, Mikk; Truu, Marika; Mander, Ülo; Kasak, Kuno; Nõlvak, Hiie; Ligi, Teele; Oopkaup, Kristjan; Maddison, Martin; Truu, Jaak

2018-03-16

Tropical peatlands, which play a crucial role in the maintenance of different ecosystem services, are increasingly drained for agriculture, forestry, peat extraction and human settlement purposes. The present study investigated the differences between natural and drained sites of a tropical peatland in the community structure of soil bacteria and archaea and their potential to perform nitrogen transformation processes. The results indicate significant dissimilarities in the structure of soil bacterial and archaeal communities as well as nirK, nirS, nosZ, nifH and archaeal amoA gene-possessing microbial communities. The reduced denitrification and N 2 -fixing potential was detected in the drained tropical peatland soil. In undisturbed peatland soil, the N 2 O emission was primarily related to nirS-type denitrifiers and dissimilatory nitrate reduction to ammonium, while the conversion of N 2 O to N 2 was controlled by microbes possessing nosZ clade I genes. The denitrifying microbial community of the drained site differed significantly from the natural site community. The main reducers of N 2 O were microbes harbouring nosZ clade II genes in the drained site. Additionally, the importance of DNRA process as one of the controlling mechanisms of N 2 O fluxes in the natural peatlands of the tropics revealed from the results of the study.

In situ biodenitrification of nitrate surface water

International Nuclear Information System (INIS)

Schmidt, G.C.; Ballew, M.B.

1995-01-01

The US Department of Energy's Weldon Spring Site Remedial Action Project has successfully operated a full-scale in situ biodenitrification system to treat water with elevated nitrate levels in abandoned raffinate pits. Bench- and pilot-scale studies were conducted to evaluate the feasibility of the process and to support its full-scale design and application. Bench testing evaluated variables that would influence development of an active denitrifying biological culture. The variables were carbon source, phosphate source, presence and absence of raffinate sludge, addition of a commercially available denitrifying microbial culture, and the use of a microbial growth medium. Nitrate levels were reduced from 750 mg/L NO 3 -N to below 10 mg/L NO 3 -N within 17 days. Pilot testing simulated the full-scale process to determine if nitrate levels could be reduced to less than 10 mg/L NO 3 -N when high levels are present below the sludge surface. Four separate test systems were examined along with two control systems. Nitrates were reduced from 1,200 mg/L NO 3 -N to below 2 mg/L NO 3 -N within 21 days. Full-scale operation has been initiated to denitrify 900,000-gal batches alternating between two 1-acre ponds. The process used commercially available calcium acetate solution and monosodium/disodium phosphate solution as a nutrient source for indigenous microorganisms to convert nitrates to molecular nitrogen and water

Protective effects of Spirulina maxima on hyperlipidemia and oxidative-stress induced by lead acetate in the liver and kidney.

Science.gov (United States)

Ponce-Canchihuamán, Johny C; Pérez-Méndez, Oscar; Hernández-Muñoz, Rolando; Torres-Durán, Patricia V; Juárez-Oropeza, Marco A

2010-03-31

Oxidative damage has been proposed as a possible mechanism involved in lead toxicity, specially affecting the liver and kidney. Previous studies have shown the antioxidant effect of Spirulina maxima in several experimental models of oxidative stress. The current study was carried out to evaluate the antioxidant activity of Spirulina maxima against lead acetate-induced hyperlipidemia and oxidative damage in the liver and kidney of male rats. Control animals were fed on a standard diet and did not receive lead acetate (Control group). Experimental animals were fed on a standard laboratory diet with or without Spirulina maxima 5% in the standard laboratory diet and treated with three doses of lead acetate (25 mg each/weekly, intraperitoneal injection) (lead acetate with Spirulina, and lead acetate without Spirulina groups). The results showed that Spirulina maxima prevented the lead acetate-induced significant changes on plasma and liver lipid levels and on the antioxidant status of the liver and kidney. On the other hand, Spirulina maxima succeeded to improve the biochemical parameters of the liver and kidney towards the normal values of the Control group. It was concluded that Spirulina maxima has protective effects on lead acetate-induced damage, and that the effects are associated with the antioxidant effect of Spirulina.

Effects of rapeseed meal fiber content on phosphorus and calcium digestibility in growing pigs fed diets without or with microbial phytase.

Science.gov (United States)

Bournazel, M; Lessire, M; Duclos, M J; Magnin, M; Même, N; Peyronnet, C; Recoules, E; Quinsac, A; Labussière, E; Narcy, A

2018-01-01

The optimization of dietary phosphorus (P) and calcium (Ca) supply requires a better understanding of the effect of dietary fiber content of co-products on the digestive utilization of minerals. This study was designed to evaluate the effects of dietary fiber content from 00-rapeseed meal (RSM) on P and Ca digestibility throughout the gastrointestinal tract in growing pigs fed diets without or with microbial phytase. In total, 48 castrated male pigs (initial BW=36.1±0.4 kg) were housed in metabolic crates for 29 days. After an 8-day adaptation period, pigs were allocated to one of the eight treatments. The impact of dietary fiber was modulated by adding whole RSM (wRSM), dehulled RSM (dRSM) or dRSM supplemented with 4.5% or 9.0% rapeseed hulls (dRSMh1 and dRSMh2). Diets contained 0 or 500 phytase unit of microbial phytase per kg. From day 14 to day 23, feces and urine were collected separately to determine apparent total tract digestibility (ATTD) and apparent retention (AR) of P and Ca. At the end of the experiment, femurs and digestive contents were sampled. No effect of variables of interest was observed on growth performance. Microbial phytase increased ATTD and AR of P (Pphytase (Pphytase which increased AR of Ca and femur characteristics (Pphytase but cecal recovery was considerably reduced by microbial phytase (Pphytase and R 2=0.24, P=0.026 with microbial phytase). The inclusion of hulls improved the solubility of iP (Pphytase in releasing phosphate in the stomach. Moreover, dietary fiber may affect solubilization process in the cecum which potentiates the effect of microbial phytase on P digestibility.

Effects of zinc oxide and microbial phytase on digestibility of calcium and phosphorus in maize-based diets fed to growing pigs.

Science.gov (United States)

Blavi, L; Sola-Oriol, D; Perez, J F; Stein, H H

2017-02-01

An experiment was conducted to test the hypothesis that inclusion of Zn at a pharmacological level in diets fed to pigs affects apparent total tract digestibility (ATTD) of Ca and P and standardized total tract digestibility (STTD) of Ca. The second hypothesis was that inclusion of microbial phytase increases the ATTD of Ca and P and the STTD of Ca regardless of the concentration of Zn in the diet. Fifty-six growing barrows (15.4 ± 1.9 kg average BW) were allotted to a randomized complete block design with 7 dietary treatments and 8 pigs per treatment. A maize-based basal diet was formulated with either 0 or 2,400 mg/kg Zn from ZnO and 0, 1,000, or 3,000 units of phytase (FTU) per kilogram. A Ca-free diet was used to determine basal endogenous losses of Ca. Experimental diets were fed for 13 d, and feces were collected from the feed provided from d 6 to 11 using the marker-to-marker approach; urine was also collected from d 6 to 11. Retention of Ca, ATTD of Ca, and STTD of Ca increased ( phytase in the diet increased and were less ( phytase increased in the diet, but the increase was greater if ZnO was not added than if ZnO was added to the diet (interaction, phytase in the diets. Inclusion of microbial phytase increased the ATTD and STTD of Ca in diets and also the ATTD of P.

Effects of engineered nanomaterials on microbial catalyzed biogeochemical processes in sediments

Energy Technology Data Exchange (ETDEWEB)

Gao Jie, E-mail: jgao@perc.ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Wang Yu; Hovsepyan, Anna [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Bonzongo, Jean-Claude J., E-mail: bonzongo@ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States)

2011-02-15

Engineered nanomaterials (ENMs) are anticipated to find use in many human activities and commercial products. Concerns are therefore being raised regarding their environmental fate and toxicological implications, which remain largely unknown. In this study, we investigate the effects of C{sub 60}, nano-Ag and CdSe quantum dots (QD) on microbial-catalyzed oxidation of organic matter in freshwater sediments. Sediment slurries spiked with sodium acetate at a final concentration of 150 mg/L were separately treated with pre-identified toxic levels of the tested ENMs. The study focused primarily on acetate oxidation by nitrate reducing bacteria. Sediment slurries were incubated under anaerobic conditions in parallel with control samples, and changes in concentrations of acetate, nitrate and nitrite tracked over time. The results showed that tested C{sub 60} concentration completely inhibited the microbial oxidation of acetate, whereas the addition of nano-Ag and CdSe QD to sediment slurries negatively affected the rates of acetate oxidation. Under conditions with nitrate as prevalent electron acceptor, reaction rates of acetate degradation decreased from 0.44 day{sup -1} in control slurries to 0.24 day{sup -1} and 0.20 day{sup -1} in slurries treated with nano-Ag and CdSe QD, respectively. These preliminary results call for further investigations on potential long-term effects of ENMs on microbial driven basic ecosystem services.

Faecal microbiota of forage-fed horses in New Zealand and the population dynamics of microbial communities following dietary change.

Directory of Open Access Journals (Sweden)

Karlette A Fernandes

Full Text Available The effects of abrupt dietary transition on the faecal microbiota of forage-fed horses over a 3-week period were investigated. Yearling Thoroughbred fillies reared as a cohort were exclusively fed on either an ensiled conserved forage-grain diet ("Group A"; n = 6 or pasture ("Group B"; n = 6 for three weeks prior to the study. After the Day 0 faecal samples were collected, horses of Group A were abruptly transitioned to pasture. Both groups continued to graze similar pasture for three weeks, with faecal samples collected at 4-day intervals. DNA was isolated from the faeces and microbial 16S and 18S rRNA gene amplicons were generated and analysed by pyrosequencing. The faecal bacterial communities of both groups of horses were highly diverse (Simpson's index of diversity > 0.8, with differences between the two groups on Day 0 (P < 0.017 adjusted for multiple comparisons. There were differences between Groups A and B in the relative abundances of four genera, BF311 (family Bacteroidaceae; P = 0.003, CF231 (family Paraprevotellaceae; P = 0.004, and currently unclassified members within the order Clostridiales (P = 0.003 and within the family Lachnospiraceae (P = 0.006. The bacterial community of Group A horses became similar to Group B within four days of feeding on pasture, whereas the structure of the archaeal community remained constant pre- and post-dietary change. The community structure of the faecal microbiota (bacteria, archaea and ciliate protozoa of pasture-fed horses was also identified. The initial differences observed appeared to be linked to recent dietary history, with the bacterial community of the forage-fed horses responding rapidly to abrupt dietary change.

Anaerobic/oxic/anoxic granular sludge process as an effective nutrient removal process utilizing denitrifying polyphosphate-accumulating organisms.

Science.gov (United States)

Kishida, Naohiro; Kim, Juhyun; Tsuneda, Satoshi; Sudo, Ryuichi

2006-07-01

In a biological nutrient removal (BNR) process, the utilization of denitrifying polyphosphate-accumulating organisms (DNPAOs) has many advantages such as effective use of organic carbon substrates and low sludge production. As a suitable process for the utilization of DNPAOs in BNR, an anaerobic/oxic/anoxic granular sludge (AOAGS) process was proposed in this study. In spite of performing aeration for nitrifying bacteria, the AOAGS process can create anaerobic/anoxic conditions suitable for the cultivation of DNPAOs because anoxic zones exist inside the granular sludge in the oxic phase. Thus, DNPAOs can coexist with nitrifying bacteria in a single reactor. In addition, the usability of DNPAOs in the reactor can be improved by adding the anoxic phase after the oxic phase. These characteristics enable the AOAGS process to attain effective removal of both nitrogen and phosphorus. When acetate-based synthetic wastewater (COD: 600 mg/L, NH4-N: 60 mg/L, PO(4)-P: 10 mg/L) was supplied to a laboratory-scale sequencing batch reactor under the operation of anaerobic/oxic/anoxic cycles, granular sludge with a diameter of 500 microm was successfully formed within 1 month. Although the removal of both nitrogen and phosphorus was almost complete at the end of the oxic phase, a short anoxic period subsequent to the oxic phase was necessary for further removal of nitrogen and phosphorus. As a result, effluent concentrations of NH(4)-N, NO(x)-N and PO(4)-P were always lower than 1 mg/L. It was found that penetration depth of oxygen inside the granular sludge was approximately 100 microm by microsensor measurements. In addition, from the microbiological analysis by fluorescence in situ hybridization, existence depth of polyphosphate-accumulating organisms was further than the maximum oxygen penetration depth. The water quality data, oxygen profiles and microbial community structure demonstrated that DNPAOs inside the granular sludge may be responsible for denitrification in the

Quantification of the methane concentration using anaerobic oxidation of methane coupled to extracellular electron transfer

Science.gov (United States)

A biofilm anode acclimated with acetate, acetate+methane, and methane growth media for over three years produced a steady current density of 1.6-2.3 mA/m^2 in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for...

Multi-electrode continuous flow microbial electrolysis cell for biogas production from acetate

Energy Technology Data Exchange (ETDEWEB)

Rader, Geoffrey K.; Logan, Bruce E. [Department of Civil and Environmental Engineering, Penn State University, University Park, PA 16802 (United States)

2010-09-15

Most microbial electrolysis cells (MECs) contain only a single set of electrodes. In order to examine the scalability of a multiple-electrode design, we constructed a 2.5 L MEC containing 8 separate electrode pairs made of graphite fiber brush anodes pre-acclimated for current generation using acetate, and 304 stainless steel mesh cathodes (64 m{sup 2}/m{sup 3}). Under continuous flow conditions and a one day hydraulic retention time, the maximum current was 181 mA (1.18 A/m{sup 2}, cathode surface area; 74 A/m{sup 3}) within three days of operation. The maximum hydrogen production (day 3) was 0.53 L/L-d, reaching an energy efficiency relative to electrical energy input of {eta}{sub E} = 144%. Current production remained relatively steady (days 3-18), but the gas composition dramatically shifted over time. By day 16, there was little H{sub 2} gas recovered and methane production increased from 0.049 L/L-d (day 3) to 0.118 L/L-d. When considering the energy value of both hydrogen and methane, efficiency relative to electrical input remained above 100% until near the end of the experiment (day 17) when only methane gas was being produced. Our results show that MECs can be scaled up primarily based on cathode surface area, but that hydrogen can be completely consumed in a continuous flow system unless methanogens can be completely eliminated from the system. (author)

Multi-electrode continuous flow microbial electrolysis cell for biogas production from acetate

KAUST Repository

Rader, Geoffrey K.; Logan, Bruce E.

2010-01-01

Most microbial electrolysis cells (MECs) contain only a single set of electrodes. In order to examine the scalability of a multiple-electrode design, we constructed a 2.5 L MEC containing 8 separate electrode pairs made of graphite fiber brush anodes pre-acclimated for current generation using acetate, and 304 stainless steel mesh cathodes (64 m2/m3). Under continuous flow conditions and a one day hydraulic retention time, the maximum current was 181 mA (1.18 A/m2, cathode surface area; 74 A/m 3) within three days of operation. The maximum hydrogen production (day 3) was 0.53 L/L-d, reaching an energy efficiency relative to electrical energy input of ηE = 144%. Current production remained relatively steady (days 3-18), but the gas composition dramatically shifted over time. By day 16, there was little H2 gas recovered and methane production increased from 0.049 L/L-d (day 3) to 0.118 L/L-d. When considering the energy value of both hydrogen and methane, efficiency relative to electrical input remained above 100% until near the end of the experiment (day 17) when only methane gas was being produced. Our results show that MECs can be scaled up primarily based on cathode surface area, but that hydrogen can be completely consumed in a continuous flow system unless methanogens can be completely eliminated from the system. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Multi-electrode continuous flow microbial electrolysis cell for biogas production from acetate

KAUST Repository

Rader, Geoffrey K.

2010-09-01

Most microbial electrolysis cells (MECs) contain only a single set of electrodes. In order to examine the scalability of a multiple-electrode design, we constructed a 2.5 L MEC containing 8 separate electrode pairs made of graphite fiber brush anodes pre-acclimated for current generation using acetate, and 304 stainless steel mesh cathodes (64 m2/m3). Under continuous flow conditions and a one day hydraulic retention time, the maximum current was 181 mA (1.18 A/m2, cathode surface area; 74 A/m 3) within three days of operation. The maximum hydrogen production (day 3) was 0.53 L/L-d, reaching an energy efficiency relative to electrical energy input of ηE = 144%. Current production remained relatively steady (days 3-18), but the gas composition dramatically shifted over time. By day 16, there was little H2 gas recovered and methane production increased from 0.049 L/L-d (day 3) to 0.118 L/L-d. When considering the energy value of both hydrogen and methane, efficiency relative to electrical input remained above 100% until near the end of the experiment (day 17) when only methane gas was being produced. Our results show that MECs can be scaled up primarily based on cathode surface area, but that hydrogen can be completely consumed in a continuous flow system unless methanogens can be completely eliminated from the system. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Antibiotics and Manure Effects on Microbial Communities Responsible for Nitrous Oxide Emissions from Grasslands

Science.gov (United States)

Semedo, M.; Song, B.; Sparrer, T.; Crozier, C.; Tobias, C. R.; Phillips, R. L.

2015-12-01

Agroecosystems are major contributors of nitrous oxide (N2O) emissions. Denitrification and nitrification are the primary pathways of N2O emission in soils. However, there is uncertainty regarding the organisms responsible for N2O production. Bacteria were previously considered the only microbial N2O source, however, current studies indicate that fungi also produce N2O by denitrification. Denitrifying bacteria can be a source or sink of N2O depending on the presence and expression of nitrous oxide reductase genes (nosZ), encoding for the enzyme converting N2O to N2. Fungal denitrification may produce only N2O as an end product due to missing the nosZ gene. Animal manures applied to agricultural fields can transfer antibiotics to soils as a result of antibiotic use in the livestock industry. These antibiotics target mostly bacteria and may promote fungal growth. The growth inhibition of denitrifying bacteria may favor fungal denitrifiers potentially enhancing N2O emissions. Our objective is to examine the effects of antibiotic exposure and manure fertilization on the microbial communities responsible for N2 and N2O production in grasslands. Soil slurry incubations were conducted with tetracycline at different concentrations. A mesocosm experiment was also performed with soil cores exposed to tetracycline and cow manure. Production of N2O and N2 was measured using gas chromatography with electron capture detector (GC-ECD) and isotope ratio mass spectrometry (IRMS), respectively. Antibiotic inhibition of soil N2 production was found to be dose dependent, reaching up to 80% inhibition with 1g Kg-1 of tetracycline treatment, while N2O production was enhanced up to 8 times. These results suggest higher fungal denitrification with a concomitant decrease in bacterial denitrification after antibiotic exposure. We also found higher N2O fluxes in the soil mesocosms treated with manure plus tetracycline. Quantitative PCR (qPCR) will be conducted to examine the changes in

In situ detection of denitrifying bacteria by mRNA-targeted nucleic acid probes and catalyzed reporter deposition

DEFF Research Database (Denmark)

Kofoed, Michael Vedel; Stief, Peter; Poulsen, Morten

can be designed to target a broader range of denitrifying bacteria; however, they require two-pass CARD-FISH, which may result in (too) high background fluorescence. In a first application example, habitat-specific polynucleotide probes were used to quantify bacteria expressing narG and nos...... reduction of nitrate to dinitrogen gas, is essential for the removal of fixed nitrogen from natural and engineered ecosystems. However, community structure and activity dynamics of denitrifying bacteria in most systems are poorly understood, partially due to difficulties in identifying and quantifying...... and catalyzed fluorescent reporter deposition (CARD-FISH). The general feasibility of the approach was first tested with pure cultures of Pseudomonas stutzeri and various denitrifying and nitrate-reducing isolates. Detailed studies of probe specificity and hybridization conditions using Clone-FISH of nar...

Plastic carrier polishing chamber reduces pollution swapping from denitrifying woodchip bioreactors

Science.gov (United States)

Denitrifying bioreactors with solid organic carbon sources (i.e., “woodchip bioreactors”) have proven to be relatively simple and cost effective treatment systems for nitrate-laden agricultural and aquacultural waters and wastewaters. However, because this technology is still relatively new, design ...

Flow-through Column Experiments and Modeling of Microbially Mediated Cr(VI) Reduction at Hanford 100H

Science.gov (United States)

Yang, L.; Molins, S.; Beller, H. R.; Brodie, E. L.; Steefel, C.; Nico, P. S.; Han, R.

2010-12-01

Microbially mediated Cr(VI) reduction at the Hanford 100H area was investigated by flow-through column experiments. Three separate experiments were conducted to promote microbial activities associated with denitrification, iron and sulfate reduction, respectively. Replicate columns packed with natural sediments from the site under anaerobic environment were injected with 5mM Lactate as the electron donor and 5 μM Cr(VI) in all experiments. Sulfate and nitrate solutions were added to act as the main electron acceptors in the respective experiments, while iron columns relied on the indigenous sediment iron (and manganese) oxides as electron acceptors. Column effluent solutions were analyzed by IC and ICP-MS to monitor the microbial consumption/conversion of lactate and the associated Cr(VI) reduction. Biogeochemical reactive transport modeling was performed to gain further insights into the reaction mechanisms and Cr(VI) bioreduction rates. All experimental columns showed a reduction of the injected Cr(VI). Columns under denitrifying conditions showed the least Cr(VI) reduction at early stages (simulations indicated that biomass growth completely depleted influent ammonium, and called for an additional source of N to account for the measured reduction rates. Iron columns were the least active with undetectable consumption of the injected lactate, slowest cell growth, and the smallest change in Cr(VI) concentrations during the course of the experiment. In contrast, columns under sulfate-reducing/fermentative conditions exhibited the greatest Cr(VI) reduction capacity. Two sulfate columns evolved to complete lactate fermentation with acetate and propionate produced in the column effluent after 40 days of experiments. These fermenting columns showed a complete removal of injected Cr(VI), visible precipitation of sulfide minerals, and a significant increase in effluent Fe and Mn concentrations. Reactive transport simulations suggested that direct reduction of Cr(VI) by

Shifts in microbial populations in Rusitec fermenters as affected by the type of diet and impact of the method for estimating microbial growth (15N v. microbial DNA).

Science.gov (United States)

Mateos, I; Ranilla, M J; Saro, C; Carro, M D

2017-11-01

Rusitec fermenters are in vitro systems widely used to study ruminal fermentation, but little is known about the microbial populations establishing in them. This study was designed to assess the time evolution of microbial populations in fermenters fed medium- (MC; 50% alfalfa hay : concentrate) and high-concentrate diets (HC; 15 : 85 barley straw : concentrate). Samples from solid (SOL) and liquid (LIQ) content of fermenters were taken immediately before feeding on days 3, 8 and 14 of incubation for quantitative polymerase chain reaction and automated ribosomal intergenic spacer analysis analyses. In SOL, total bacterial DNA concentration and relative abundance of Ruminococcus flavefaciens remained unchanged over the incubation period, but protozoal DNA concentration and abundance of Fibrobacter succinogenes, Ruminococcus albus and fungi decreased and abundance of methanogenic archaea increased. In LIQ, total bacterial DNA concentration increased with time, whereas concentration of protozoal DNA and abundance of methanogens and fungi decreased. Diet×time interactions were observed for bacterial and protozoal DNA and relative abundance of F. succinogenes and R. albus in SOL, as well as for protozoal DNA in LIQ. Bacterial diversity in SOL increased with time, but no changes were observed in LIQ. The incubated diet influenced all microbial populations, with the exception of total bacteria and fungi abundance in LIQ. Bacterial diversity was higher in MC-fed than in HC-fed fermenters in SOL, but no differences were detected in LIQ. Values of pH, daily production of volatile fatty acids and CH4 and isobutyrate proportions remained stable over the incubation period, but other fermentation parameters varied with time. The relationships among microbial populations and fermentation parameters were in well agreement with those previously reported in in vivo studies. Using 15N as a microbial marker or quantifying total microbial DNA for estimating microbial protein synthesis

Use of novel permeable membrane and air cathodes in acetate microbial fuel cells

Energy Technology Data Exchange (ETDEWEB)

Pant, Deepak, E-mail: deepak.pant@vito.b [Separation and Conversion Technology, VITO - Flemish Institute for Technological Research, Boeretang 200, Mol 2400 (Belgium); Van Bogaert, Gilbert; De Smet, Mark; Diels, Ludo; Vanbroekhoven, Karolien [Separation and Conversion Technology, VITO - Flemish Institute for Technological Research, Boeretang 200, Mol 2400 (Belgium)

2010-11-01

In the existing microbial fuel cells (MFCs), the use of platinized electrodes and Nafion as proton exchange membrane (PEM) leads to high costs leading to a burden for wastewater treatment. In the present study, two different novel electrode materials are reported which can replace conventional platinized electrodes and can be used as very efficient oxygen reducing cathodes. Further, a novel membrane which can be used as an ion permeable membrane (Zirfon) can replace Nafion as the membrane of choice in MFCs. The above mentioned gas porous electrodes were first tested in an electrochemical half cell configuration for their ability to reduce oxygen and later in a full MFC set up. It was observed that these non-platinized air electrodes perform very well in the presence of acetate under MFC conditions (pH 7, room temperature) for oxygen reduction. Current densities of -0.43 mA cm{sup -2} for a non-platinized graphite electrode and -0.6 mA cm{sup -2} for a non-platinized activated charcoal electrode at -200 mV vs. Ag/AgCl of applied potential were obtained. The proposed ion permeable membrane, Zirfonwas tested for its oxygen mass transfer coefficient, K{sub 0} which was compared with Nafion. The K{sub 0} for Zirfon was calculated as 1.9 x 10{sup -3} cm s{sup -1}.

Microbial acetate oxidation in horizontal rotating tubular bioreactor

Indian Academy of Sciences (India)

Unknown

shaped partition walls that served as carriers for micro- bial biomass. Mixing ... from soil sample collected from Zagreb mountain. This microbial culture was ... HRTB was made of a plastic tube 1⋅8 m long with an inner diameter of 0⋅25 m.

Impact of feed withdrawal and addition of acetic acid in drinking ...

African Journals Online (AJOL)

ALI GILANI

2012-11-02

Nov 2, 2012 ... 1.5, 3, 4.5 or 6% acetic acid added to their drinking water with feed ... contents of birds with acidified water in comparison to the control and feed withdrawal treatments. .... more hygienic evisceration process or lower microbial.

Fundamental Insights into Propionate Oxidation in Microbial Electrolysis Cells Using a Combination of Electrochemical, Molecular biology and Electron Balance Approaches

KAUST Repository

Rao, Hari Ananda

2016-11-01

dynamics of microbial communities in MECs fed with low or high concentration of acetate or propionate relating to the reactor performance. Overall, the findings from these studies provides new knowledge on propionate oxidation in MECs. The discovery of such findings may shed light on the development of an energy positive wastewater treatment process capable of producing a high quality effluent.

Sustainable remediation: electrochemically assisted microbial dechlorination of tetrachloroethene-contaminated groundwater.

Science.gov (United States)

Patil, Sayali S; Adetutu, Eric M; Rochow, Jacqueline; Mitchell, James G; Ball, Andrew S

2014-01-01

Microbial electric systems (MESs) hold significant promise for the sustainable remediation of chlorinated solvents such as tetrachlorethene (perchloroethylene, PCE). Although the bio-electrochemical potential of some specific bacterial species such as Dehalcoccoides and Geobacteraceae have been exploited, this ability in other undefined microorganisms has not been extensively assessed. Hence, the focus of this study was to investigate indigenous and potentially bio-electrochemically active microorganisms in PCE-contaminated groundwater. Lab-scale MESs were fed with acetate and carbon electrode/PCE as electron donors and acceptors, respectively, under biostimulation (BS) and BS-bioaugmentation (BS-BA) regimes. Molecular analysis of the indigenous groundwater community identified mainly Spirochaetes, Firmicutes, Bacteroidetes, and γ and δ-Proteobacteria. Environmental scanning electron photomicrographs of the anode surfaces showed extensive indigenous microbial colonization under both regimes. This colonization and BS resulted in 100% dechlorination in both treatments with complete dechlorination occurring 4 weeks earlier in BS-BA samples and up to 11.5 μA of current being generated. The indigenous non-Dehalococcoides community was found to contribute significantly to electron transfer with ∼61% of the current generated due to their activities. This study therefore shows the potential of the indigenous non-Dehalococcoides bacterial community in bio-electrochemically reducing PCE that could prove to be a cost-effective and sustainable bioremediation practice. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

The electric picnic: synergistic requirements for exoelectrogenic microbial communities

KAUST Repository

Kiely, Patrick D; Regan, John M; Logan, Bruce E

2011-01-01

(BESs). Analysis of the community profiles of exoelectrogenic microbial consortia in BESs fed different substrates gives a clearer picture of the different microbial populations present in these exoelectrogenic biofilms. Rapid utilization of fermentation

Anaerobic degradation of long-chain alkylamines by a denitrifying Pseudomonas stutzeri

NARCIS (Netherlands)

Nguyen, P.D.; Ginkel, van C.G.; Plugge, C.M.

2008-01-01

The anaerobic degradation of tetradecylamine and other long-chain alkylamines by a newly isolated denitrifying bacterium was studied. Strain ZN6 was isolated from a mixture of soil and active sludge and was identified as representing Pseudomonas stutzeri, based on partial 16S rRNA gene sequence

Conductive iron oxides accelerate thermophilic methanogenesis from acetate and propionate.

Science.gov (United States)

Yamada, Chihaya; Kato, Souichiro; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

2015-06-01

Anaerobic digester is one of the attractive technologies for treatment of organic wastes and wastewater, while continuous development and improvements on their stable operation with efficient organic removal are required. Particles of conductive iron oxides (e.g., magnetite) are known to facilitate microbial interspecies electron transfer (termed as electric syntrophy). Electric syntrophy has been reported to enhance methanogenic degradation of organic acids by mesophilic communities in soil and anaerobic digester. Here we investigated the effects of supplementation of conductive iron oxides (magnetite) on thermophilic methanogenic microbial communities derived from a thermophilic anaerobic digester. Supplementation of magnetite accelerated methanogenesis from acetate and propionate under thermophilic conditions, while supplementation of ferrihydrite also accelerated methanogenesis from propionate. Microbial community analysis revealed that supplementation of magnetite drastically changed bacterial populations in the methanogenic acetate-degrading cultures, in which Tepidoanaerobacter sp. and Coprothermobacter sp. dominated. These results suggest that supplementation of magnetite induce electric syntrophy between organic acid-oxidizing bacteria and methanogenic archaea and accelerate methanogenesis even under thermophilic conditions. Findings from this study would provide a possibility for the achievement of stably operating thermophilic anaerobic digestion systems with high efficiency for removal of organics and generation of CH4. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Microbial Nitrogen-Cycle Gene Abundance in Soil of Cropland Abandoned for Different Periods.

Science.gov (United States)

Huhe; Borjigin, Shinchilelt; Buhebaoyin; Wu, Yanpei; Li, Minquan; Cheng, Yunxiang

2016-01-01

In Inner Mongolia, steppe grasslands face desertification or degradation because of human overuse and abandonment after inappropriate agricultural management. The soils in these abandoned croplands exist in heterogeneous environments characterized by widely fluctuating microbial growth. Quantitative polymerase chain reaction analysis of microbial genes encoding proteins involved in the nitrogen cycle was used to study Azotobacter species, nitrifiers, and denitrifiers in the soils from steppe grasslands and croplands abandoned for 2, 6, and 26 years. Except for nitrifying archaea and nitrous oxide-reducing bacteria, the relative genotypic abundance of microbial communities involved in nitrogen metabolism differed by approximately 2- to 10-fold between abandoned cropland and steppe grassland soils. Although nitrogen-cycle gene abundances varied with abandonment time, the abundance patterns of nitrogen-cycle genes separated distinctly into abandoned cropland versus light-grazing steppe grassland, despite the lack of any cultivation for over a quarter-century. Plant biomass and plant diversity exerted a significant effect on the abundance of microbial communities that mediate the nitrogen cycle (P nitrogen cycle in recently abandoned croplands.

Reductive dehalogenation in microbial and electrolytic model systems

International Nuclear Information System (INIS)

Criddle, C.S.

1990-01-01

This research addresses the principles or reductive dehalogenation, with a focus on microbial processes. Carbon tetrachloride (CT) was selected as a model compound for intensive investigation. Three different experimental systems were studied: pure cultures of Escherichia coli k-12, pure cultures of a denitrifying Pseudomonad isolated from aquifer solids (Pseudomonas sp. strain KC), and an electrolysis cell. The product distributions were consistent with the hypothesis that CT undergoes a rate-limiting reduction to radical species which rapidly react with constituents of the surrounding milieu. In cultures of E. coli k-12, use of oxygen and nitrate as terminal electron acceptors generally prevented CT transformation. At low oxygen levels (∼ 1%), however, transformation of 14 C-CT to 14 C-CO 2 and attachment to cell material did occur in accord with reports of CT fate in mammalian cell cultures. Under fumarate-respiring conditions, 14 C-CT was recovered as 14 C-C 2 , chloroform (CF), and in a non-volatile fraction. In contrast, fermenting conditions resulted in more CF, more cell-bound 14 C, and almost no 14 C-CO 2 . Rates were faster under fermenting conditions than under fumarate-respiring conditions. Rates also decreased over time suggesting the gradual exhaustion of transformation activity. This loss was modeled with a simple exponential decay term. Pseudomonas sp. strain KC converted 14 C-CT to 14 C-CO 2 under denitrifying conditions, without CF production. Strain KC was the only organism of several denitrifiers that transformed CT. Induction of CT transformation by strain KC depended upon the presence of trace metals. Addition of ferrous iron and cobalt inhibited CT transformation. For strain KC, CT transformation is apparently linked to its mechanism for trace metal acquisition

Bioavailability and biodegradation of weathered diesel fuel in aquifer material under denitrifying conditions

International Nuclear Information System (INIS)

Bregnard, T.P.A.; Hoehener, P.; Zeyer, J.

1998-01-01

During the in situ bioremediation of a diesel fuel-contaminated aquifer in Menziken, Switzerland, aquifer material containing weathered diesel fuel (WDF) and indigenous microorganisms was excavated. This material was used to identify factors limiting WDF biodegradation under denitrifying conditions. Incubations of this material for 360 to 390 d under denitrifying conditions resulted in degradation of 23% of the WDF with concomitant consumption of NO 3 - and production of inorganic carbon. The biodegradation of WDF and the rate of NO 3 - consumption was stimulated by agitation of the microcosms. Biodegradation was not stimulated by the addition of a biosurfactant (rhamnolipids) or a synthetic surfactant (Triton X-100) at concentrations above their critical micelle concentrations. The rhamnolipids were biodegraded preferentially to WDF, whereas Triton X-100 was not degraded. Both surfactants reduced the surface tension of the growth medium from 72 to <35 dynes/cm and enhanced the apparent aqueous solubility of the model hydrocarbon n-hexadecane by four orders of magnitude. Solvent-extracted WDF, added at a concentration equal to that already present in the aquifer material, was also biodegraded by the microcosms, but not at a higher rate than the WDF already present in the material. The results show that the denitrifying biodegradation of WDF is not necessarily limited by bioavailability but rather by the inherent recalcitrance of WDF

Corn silage in dairy cow diets to reduce ruminal methanogenesis: effects on the rumen metabolically active microbial communities.

Science.gov (United States)

Lettat, A; Hassanat, F; Benchaar, C

2013-08-01

Methane produced by the methanogenic Archaea that inhabit the rumen is a potent greenhouse gas and represents an energy loss for the animal. Although several strategies have been proposed to mitigate enteric CH4 production, little is known about the effects of dietary changes on the microbial consortia involved in ruminal methanogenesis. Thus, the current study aimed to examine how the metabolically active microbes are affected when dairy cows were fed diets with increasing proportions of corn silage (CS). For this purpose, 9 ruminally cannulated lactating dairy cows were used in a replicated 3 × 3 Latin square design and fed a total mixed ration (60:40 forage:concentrate ratio on a dry matter basis) with the forage portion being either alfalfa silage (0% CS), corn silage (100% CS), or a 50:50 mixture (50% CS). Enteric CH4 production was determined using respiration chambers and total rumen content was sampled for the determination of fermentation characteristics and molecular biology analyses (cDNA-based length heterogeneity PCR, quantitative PCR). The cDNA-based length heterogeneity PCR targeting active microbes revealed similar bacterial communities in cows fed 0% CS and 50% CS diets, whereas important differences were observed between 0% CS and 100% CS diets, including a reduction in the bacterial richness and diversity in cows fed 100% CS diet. As revealed by quantitative PCR, feeding the 100% CS diet increased the number of total bacteria, Prevotella spp., Archaea, and methanogenic activity, though it reduced protozoal number. Meanwhile, increasing the CS proportion in the diet increased propionate concentration but decreased ruminal pH, CH4 production (L/kg of dry matter intake), and concentrations of acetate and butyrate. Based on these microbial and fermentation changes, and because CH4 production was reduced by feeding 100% CS diet, this study shows that the use of cDNA-based quantitative PCR to estimate archaeal growth and activity is not reliable

Edaphic Conditions Regulate Denitrification Directly and Indirectly by Altering Denitrifier Abundance in Wetlands along the Han River, China.

Science.gov (United States)

Xiong, Ziqian; Guo, Laodong; Zhang, Quanfa; Liu, Guihua; Liu, Wenzhi

2017-05-16

Riparian wetlands play a critical role in retaining nitrogen (N) from upland runoff and improving river water quality, mainly through biological processes such as soil denitrification. However, the relative contribution of abiotic and biotic factors to riparian denitrification capacity remains elusive. Here we report the spatiotemporal dynamics of potential and unamended soil denitrification rates in 20 wetlands along the Han River, an important water source in central China. We also quantified the abundance of soil denitrifying microorganisms using nirK and nirS genes. Results showed that soil denitrification rates were significantly different between riparian and reservoir shoreline wetlands, but not between mountain and lowland wetlands. In addition, soil denitrification rates showed strong seasonality, with higher values in August (summer) and April (spring) but lower values in January (winter). The potential and unamended denitrification rates were positively correlated with edaphic conditions (moisture and carbon concentration), denitrifier abundance, and plant species richness. Path analysis further revealed that edaphic conditions could regulate denitrification rates both directly and indirectly through their effects on denitrifier abundance. Our findings highlight that not only environmental factors, but also biotic factors including denitrifying microorganisms and standing vegetation, play an important role in regulating denitrification rate and N removal capacity in riparian wetlands.

Microbial Community Composition and Ultrastructure of Granules from a Full-Scale Anammox Reactor

KAUST Repository

Gonzalez-Gil, Graciela

2014-12-11

Granules in anammox reactors contain besides anammox bacteria other microbial communities whose identity and relationship with the anammox bacteria are not well understood. High calcium concentrations are often supplied to anammox reactors to obtain sufficient bacterial aggregation and biomass retention. The aim of this study was to provide the first characterization of bacterial and archaeal communities in anammox granules from a full-scale anammox reactor and to explore on the possible role of calcium in such aggregates. High magnification imaging using backscattered electrons revealed that anammox bacteria may be embedded in calcium phosphate precipitates. Pyrosequencing of 16S rRNA gene fragments showed, besides anammox bacteria (Brocadiacea, 32 %), substantial numbers of heterotrophic bacteria Ignavibacteriacea (18 %) and Anaerolinea (7 %) along with heterotrophic denitrifiers Rhodocyclacea (9 %), Comamonadacea (3 %), and Shewanellacea (3 %) in the granules. It is hypothesized that these bacteria may form a network in which heterotrophic denitrifiers cooperate to achieve a well-functioning denitrification system as they can utilize the nitrate intrinsically produced by the anammox reaction. This network may provide a niche for the proliferation of archaea. Hydrogenotrophic methananogens, which scavenge the key fermentation product H2, were the most abundant archaea detected. Cells resembling the polygon-shaped denitrifying methanotroph Candidatus Methylomirabilis oxyfera were observed by electron microscopy. It is hypothesized that the anammox process in a full-scale reactor triggers various reactions overall leading to efficient denitrification and a sink of carbon as biomass in anammox granules.

Microbial community composition and ultrastructure of granules from a full-scale anammox reactor.

Science.gov (United States)

Gonzalez-Gil, Graciela; Sougrat, Rachid; Behzad, Ali R; Lens, Piet N L; Saikaly, Pascal E

2015-07-01

Granules in anammox reactors contain besides anammox bacteria other microbial communities whose identity and relationship with the anammox bacteria are not well understood. High calcium concentrations are often supplied to anammox reactors to obtain sufficient bacterial aggregation and biomass retention. The aim of this study was to provide the first characterization of bacterial and archaeal communities in anammox granules from a full-scale anammox reactor and to explore on the possible role of calcium in such aggregates. High magnification imaging using backscattered electrons revealed that anammox bacteria may be embedded in calcium phosphate precipitates. Pyrosequencing of 16S rRNA gene fragments showed, besides anammox bacteria (Brocadiacea, 32%), substantial numbers of heterotrophic bacteria Ignavibacteriacea (18%) and Anaerolinea (7%) along with heterotrophic denitrifiers Rhodocyclacea (9%), Comamonadacea (3%), and Shewanellacea (3%) in the granules. It is hypothesized that these bacteria may form a network in which heterotrophic denitrifiers cooperate to achieve a well-functioning denitrification system as they can utilize the nitrate intrinsically produced by the anammox reaction. This network may provide a niche for the proliferation of archaea. Hydrogenotrophic methananogens, which scavenge the key fermentation product H2, were the most abundant archaea detected. Cells resembling the polygon-shaped denitrifying methanotroph Candidatus Methylomirabilis oxyfera were observed by electron microscopy. It is hypothesized that the anammox process in a full-scale reactor triggers various reactions overall leading to efficient denitrification and a sink of carbon as biomass in anammox granules.

Effects of Direct-fed Microbial and Pine Cone Extract on Carcass Traits and Meat Quality of Hanwoo (Korean Native Cattle

Directory of Open Access Journals (Sweden)

Muhlisin

2016-05-01

Full Text Available The carcass traits and meat quality of Hanwoo (Korean native cattle whose diets were supplemented with direct-fed microbial (DFM and pine cone extract (PCE were evaluated. Twenty head of Hanwoo steers were divided equally into four groups and for a period of 6 months were given different diets: One group was fed a basal diet as control (CON, the other three groups were fed a basal diet supplemented with DFM-1%, DFM+PCE-1% and DFM+PEC-3%, respectively. DFM+PCE3% diet resulted the lowest carcass quality grade. The loins of DFM-1% contained higher moisture and lower fat than did the loins from the CON group. The crude protein content of DFM+PCE-3% group was significantly higher than that of the other groups. The water holding capacity and Warner-Bratzler shear force of the DFM+PCE-1% and 3% groups were lower than those of the CON and DFM-1% groups. The DFM-1% and 3% groups contained lower saturated fatty acid, higher unsaturated fatty acid, mono-unsaturated fatty acid, and poly-unsaturated fatty acid than did CON and DFM+PCE 1% group. Moreover, the n6:n3 ratios of DFM-1% and DFM+PCE-1% and 3% groups were slightly lower than that of the CON group. Thus we concluded that DFM and PCE supplementation resulted healthier Hanwoo beef with lower fat content and n6:n3 ratio.

Different Land Use Intensities in Grassland Ecosystems Drive Ecology of Microbial Communities Involved in Nitrogen Turnover in Soil

OpenAIRE

Meyer, Annabel; Focks, Andreas; Radl, Viviane; Keil, Daniel; Welzl, Gerhard; Sch?ning, Ingo; Boch, Steffen; Marhan, Sven; Kandeler, Ellen; Schloter, Michael

2013-01-01

Understanding factors driving the ecology of N cycling microbial communities is of central importance for sustainable land use. In this study we report changes of abundance of denitrifiers, nitrifiers and nitrogen-fixing microorganisms (based on qPCR data for selected functional genes) in response to different land use intensity levels and the consequences for potential turnover rates. We investigated selected grassland sites being comparable with respect to soil type and climatic conditions,...

DRIVERS OF THE DYNAMICS OF DIAZOTROPHS AND DENITRIFIERS IN NORTH SEA BOTTOM WATERS AND SEDIMENTS

Directory of Open Access Journals (Sweden)

Lucas eStal

2015-07-01

Full Text Available The fixation of dinitrogen (N2 and denitrification are two opposite processes in the nitrogen cycle. The former transfers atmospheric dinitrogen gas into bound nitrogen in the biosphere, while the latter returns this bound nitrogen back to atmospheric dinitrogen. It is unclear whether or not these processes are intimately connected in any microbial ecosystem or that they are spatially and/or temporally separated. Here, we measured seafloor nitrogen fixation and denitrification as well as pelagic nitrogen fixation by using the stable isotope technique. Alongside, we measured the diversity, abundance, and activity of nitrogen-fixing and denitrifying microorganisms at three stations in the southern North Sea. Nitrogen fixation ranged from undetectable to 2.4 nmol N L-1 d-1 and from undetectable to 8.2 nmol N g-1 d-1 in the water column and seafloor, respectively. The highest rates were measured in August at Doggersbank, both for the water column and for the seafloor. Denitrification ranged from 1.7 to 208.8 µmol m-2 d-1 and the highest rates were measured in May at the Oyster Grounds. DNA sequence analysis showed sequences of nifH, a structural gene for nitrogenase, related to sequences from anaerobic sulfur/iron reducers and sulfate reducers. Sequences of the structural gene for nitrite reductase, nirS, were related to environmental clones from marine sediments. Quantitative polymerase chain reaction (qPCR data revealed the highest abundance of nifH and nirS genes at the Oyster Grounds. Quantitative reverse transcription polymerase chain reaction (qRT-PCR data revealed the highest nifH expression at Doggersbank and the highest nirS expression at the Oyster Grounds. The distribution of the diazotrophic and denitrifying communities seems to be subject to different selecting factors, leading to spatial and temporal separation of nitrogen fixation and denitrification. These selecting factors include temperature, organic matter availability, and

The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions

Science.gov (United States)

Adler, Philipp; Frey, Lasse Jannis; Berger, Antje; Bolten, Christoph Josef; Hansen, Carl Erik

2014-01-01

Acetic acid bacteria (AAB) play an important role during cocoa fermentation, as their main product, acetate, is a major driver for the development of the desired cocoa flavors. Here, we investigated the specialized metabolism of these bacteria under cocoa pulp fermentation-simulating conditions. A carefully designed combination of parallel 13C isotope labeling experiments allowed the elucidation of intracellular fluxes in the complex environment of cocoa pulp, when lactate and ethanol were included as primary substrates among undefined ingredients. We demonstrate that AAB exhibit a functionally separated metabolism during coconsumption of two-carbon and three-carbon substrates. Acetate is almost exclusively derived from ethanol, while lactate serves for the formation of acetoin and biomass building blocks. Although this is suboptimal for cellular energetics, this allows maximized growth and conversion rates. The functional separation results from a lack of phosphoenolpyruvate carboxykinase and malic enzymes, typically present in bacteria to interconnect metabolism. In fact, gluconeogenesis is driven by pyruvate phosphate dikinase. Consequently, a balanced ratio of lactate and ethanol is important for the optimum performance of AAB. As lactate and ethanol are individually supplied by lactic acid bacteria and yeasts during the initial phase of cocoa fermentation, respectively, this underlines the importance of a well-balanced microbial consortium for a successful fermentation process. Indeed, AAB performed the best and produced the largest amounts of acetate in mixed culture experiments when lactic acid bacteria and yeasts were both present. PMID:24837393

Biodegradation of isopropanol and acetone under denitrifying conditions by Thauera sp. TK001 for nitrate-mediated microbially enhanced oil recovery.

Science.gov (United States)

Fida, Tekle Tafese; Gassara, Fatma; Voordouw, Gerrit

2017-07-15

Amendment of reservoir fluid with injected substrates can enhance the growth and activity of microbes. The present study used isopropyl alcohol (IPA) or acetone to enhance the indigenous anaerobic nitrate-reducing bacterium Thauera sp. TK001. The strain was able to grow on IPA or acetone and nitrate. To monitor effects of strain TK001 on oil recovery, sand-packed columns containing heavy oil were flooded with minimal medium at atmospheric or high (400psi) pressure. Bioreactors were then inoculated with 0.5 pore volume (PV) of minimal medium containing Thauera sp. TK001 with 25mM of acetone or 22.2mM of IPA with or without 80mM nitrate. Incubation without flow for two weeks and subsequent injection with minimal medium gave an additional 17.0±6.7% of residual oil in place (ROIP) from low-pressure bioreactors and an additional 18.3% of ROIP from the high-pressure bioreactors. These results indicate that acetone or IPA, which are commonly used organic solvents, are good substrates for nitrate-mediated microbial enhanced oil recovery (MEOR), comparable to glucose, acetate or molasses, tested previously. This technology may be used for coupling biodegradation of IPA and/or acetone in waste streams to MEOR where these waste streams are generated in close proximity to an oil field. Copyright © 2017 Elsevier B.V. All rights reserved.

Performance of a pilot-scale continuous flow microbial electrolysis cell fed winery wastewater.

Science.gov (United States)

Cusick, Roland D; Bryan, Bill; Parker, Denny S; Merrill, Matthew D; Mehanna, Maha; Kiely, Patrick D; Liu, Guangli; Logan, Bruce E

2011-03-01

A pilot-scale (1,000 L) continuous flow microbial electrolysis cell was constructed and tested for current generation and COD removal with winery wastewater. The reactor contained 144 electrode pairs in 24 modules. Enrichment of an exoelectrogenic biofilm required ~60 days, which is longer than typically needed for laboratory reactors. Current generation was enhanced by ensuring adequate organic volatile fatty acid content (VFA/SCOD ≥ 0.5) and by raising the wastewater temperature (31 ± 1°C). Once enriched, SCOD removal (62 ± 20%) was consistent at a hydraulic retention time of 1 day (applied voltage of 0.9 V). Current generation reached a maximum of 7.4 A/m(3) by the planned end of the test (after 100 days). Gas production reached a maximum of 0.19 ± 0.04 L/L/day, although most of the product gas was converted to methane (86 ± 6%). In order to increase hydrogen recovery in future tests, better methods will be needed to isolate hydrogen gas produced at the cathode. These results show that inoculation and enrichment procedures are critical to the initial success of larger-scale systems. Acetate amendments, warmer temperatures, and pH control during startup were found to be critical for proper enrichment of exoelectrogenic biofilms and improved reactor performance.

Metagenomic insights into evolution of heavy metal-contaminated groundwater microbial community

Energy Technology Data Exchange (ETDEWEB)

Hemme, C.L.; Deng, Y.; Gentry, T.J.; Fields, M.W.; Wu, L.; Barua, S.; Barry, K.; Green-Tringe, S.; Watson, D.B.; He, Z.; Hazen, T.C.; Tiedje, J.M.; Rubin, E.M.; Zhou, J.

2010-07-01

Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents ({approx}50 years) has resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic diversity. Although the surviving microbial community possesses all metabolic pathways necessary for survival and growth in such an extreme environment, its structure is very simple, primarily composed of clonal denitrifying {gamma}- and {beta}-proteobacterial populations. The resulting community is overabundant in key genes conferring resistance to specific stresses including nitrate, heavy metals and acetone. Evolutionary analysis indicates that lateral gene transfer could have a key function in rapid response and adaptation to environmental contamination. The results presented in this study have important implications in understanding, assessing and predicting the impacts of human-induced activities on microbial communities ranging from human health to agriculture to environmental management, and their responses to environmental changes.

High efficient ethanol and VFAs production from gas fermentation: effect of acetate, gas and inoculum microbial composition

DEFF Research Database (Denmark)

El-Gammal, Maie; Abou-Shanab, Reda; Angelidaki, Irini

2017-01-01

In bioindustry, syngas fermentation is a promising technology for biofuel production without the use of plant biomass as sugar-based feedstock. The aim of this study was to identify optimal conditions for high efficient ethanol and volatile fatty acids (VFA) production from synthetic gas fermenta......In bioindustry, syngas fermentation is a promising technology for biofuel production without the use of plant biomass as sugar-based feedstock. The aim of this study was to identify optimal conditions for high efficient ethanol and volatile fatty acids (VFA) production from synthetic gas...... fatty acids and ethanol was achieved by the pure culture (Clostridium ragsdalei). Depending on the headspace gas composition, VFA concentrations were up to 300% higher after fermentation with Clostridium ragsdalei compared to fermentation with mixed culture. The preferred gas composition with respect...... to highest VFA concentration was pure CO (100%) regardless of microbial composition of the inoculum and media composition. The addition of acetate had a negative impact on the VFA formation which was depending on the initial gas composition in head space....

The Role of Soil Organic Matter, Nutrients, and Microbial Community Structure on the Performance of Microbial Fuel Cells

Science.gov (United States)

Rooney-Varga, J. N.; Dunaj, S. J.; Vallino, J. J.; Hines, M. E.; Gay, M.; Kobyljanec, C.

2011-12-01

Microbial fuel cells (MFCs) offer the potential for generating electricity, mitigating greenhouse gas emissions, and bioremediating pollutants through utilization of a plentiful, natural, and renewable resource: soil organic carbon. In the current study, we analyzed microbial community structure, MFC performance, and soil characteristics in different microhabitats (bulk soil, anode, and cathode) within MFCs constructed from agricultural or forest soils in order to determine how soil type and microbial dynamics influence MFC performance. MFCs were constructed with soils from agricultural and hardwood forest sites at Harvard Forest (Petersham, MA). The bulk soil characteristics were analyzed, including polyphenols, short chain fatty acids, total organic C and N, abiotic macronutrients, N and P mineralization rates, CO2 respiration rates, and MFC power output. Microbial community structure of the anodes, cathodes, and bulk soils was determined with molecular fingerprinting methods, which included terminal restriction length polymorphism (T-RFLP) analysis and 16S rRNA gene sequencing analysis. Our results indicated that MFCs constructed from agricultural soil had power output about 17 times that of forest soil-based MFCs and respiration rates about 10 times higher than forest soil MFCs. Agricultural soil MFCs had lower C:N ratios, polyphenol content, and acetate concentrations than forest soil MFCs, suggesting that active agricultural MFC microbial communities were supported by higher quality organic carbon. Microbial community profile data indicate that the microbial communities at the anode of the high power MFCs were less diverse than in low power MFCs and were dominated by Deltaproteobacteria, Geobacter, and, to a lesser extent, Clostridia, while low-power MFC anode communities were dominated by Clostridia. These data suggest that the presence of organic carbon substrate (acetate) was not the major limiting factor in selecting for highly electrogenic microbial

Production of itaconic acid from acetate by engineering acid-tolerant Escherichia coli W.

Science.gov (United States)

Noh, Myung Hyun; Lim, Hyun Gyu; Woo, Sung Hwa; Song, Jinyi; Jung, Gyoo Yeol

2018-03-01

Utilization of abundant and cheap carbon sources can effectively reduce the production cost and enhance the economic feasibility. Acetate is a promising carbon source to achieve cost-effective microbial processes. In this study, we engineered an Escherichia coli strain to produce itaconic acid from acetate. As acetate is known to inhibit cell growth, we initially screened for a strain with a high tolerance to 10 g/L of acetate in the medium, and the W strain was selected as the host. Subsequently, the WC strain was obtained by overexpression of cad (encoding cis-aconitate decarboxylase) using a synthetic promoter and 5' UTR. However, the WC strain produced only 0.13 g/L itaconic acid because of low acetate uptake. To improve the production, the acetate assimilating pathway and glyoxylate shunt pathway were amplified by overexpression of pathway genes as well as its deregulation. The resulting strain, WCIAG4 produced 3.57 g/L itaconic acid (16.1% of theoretical maximum yield) after 88 hr of fermentation with rapid acetate assimilation. These efforts support that acetate can be a potential feedstock for biochemical production with engineered E. coli. © 2017 Wiley Periodicals, Inc.

Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa.

OpenAIRE

Hernandez, D; Rowe, J J

1987-01-01

Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal...

An investigation into the preservation of microbial cell banks for α-amylase production during 5 l fed-batch Bacillus licheniformis fermentations.

Science.gov (United States)

Hancocks, Nichola H; Thomas, Colin R; Stocks, Stuart M; Hewitt, Christopher J

2010-10-01

Fluorescent staining techniques were used for a systematic examination of methods used to cryopreserve microbial cell banks. The aim of cryopreservation here is to ensure subsequent reproducible fermentation performance rather than just post thaw viability. Bacillus licheniformis cell physiology post-thaw is dependent on the cryopreservant (either Tween 80, glycerol or dimethyl sulphoxide) and whilst this had a profound effect on the length of the lag phase, during subsequent 5 l fed-batch fermentations, it had little effect on maximum specific growth rate, final biomass concentration or α-amylase activity. Tween 80 not only protected the cells during freezing but also helped them recover post-thaw resulting in shorter process times.

Bioconversion of cellulose into electrical energy in microbial fuel cells

Science.gov (United States)

Rismani-Yazdi, Hamid

In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The first objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. Maximum power density reached 55 mW/m2 (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over two months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. The second objective was to analyze the composition of the bacterial communities enriched in the cellulose-fed MFCs. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. was abundant in the suspended consortia. The external resistance affects the characteristic outputs of MFCs by controlling the flow of electrons from the anode to the cathode. The third objective of this study was to determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs. Four external resistances (20, 249, 480, and 1000 ohms) were tested with a systematic approach of operating parallel MFCs independently at constant circuit loads for three months. A maximum power density of 66 mWm-2 was achieved by MFCs with 20 ohms circuit load, while MFCs with 249, 480 and1000 ohms external resistances produced 57

Anaerobic oxidation of 2-chloroethanol under denitrifying conditions by Pseudomonas stutzeri strain JJ.

Science.gov (United States)

Dijk, J A; Stams, A J M; Schraa, G; Ballerstedt, H; de Bont, J A M; Gerritse, J

2003-11-01

A bacterium that uses 2-chloroethanol as sole energy and carbon source coupled to denitrification was isolated from 1,2-dichloroethane-contaminated soil. Its 16 S rDNA sequence showed 98% similarity with the type strain of Pseudomonas stutzeri (DSM 5190) and the isolate was tentatively identified as Pseudomonas stutzeri strain JJ. Strain JJ oxidized 2-chloroethanol completely to CO(2) with NO(3)(- )or O(2) as electron acceptor, with a preference for O(2) if supplied in combination. Optimum growth on 2-chloroethanol with nitrate occurred at 30 degrees C with a mu(max) of 0.14 h(-1) and a yield of 4.4 g protein per mol 2-chloroethanol metabolized. Under aerobic conditions, the mu(max) was 0.31 h(-1). NO(2)(-) also served as electron acceptor, but reduction of Fe(OH)(3), MnO(2), SO(4)(2-), fumarate or ClO(3)(-) was not observed. Another chlorinated compound used as sole energy and carbon source under aerobic and denitrifying conditions was chloroacetate. Various different bacterial strains, including some closely related Pseudomonas stutzeri strains, were tested for their ability to grow on 2-chloroethanol as sole energy and carbon source under aerobic and denitrifying conditions, respectively. Only three strains, Pseudomonas stutzeri strain LMD 76.42, Pseudomonas putida US2 and Xanthobacter autotrophicus GJ10, grew aerobically on 2-chloroethanol. This is the first report of oxidation of 2-chloroethanol under denitrifying conditions by a pure bacterial culture.

Nitrous oxide emission by the non-denitrifying, nitrate ammonifier Bacillus licheniformis.

Science.gov (United States)

Sun, Yihua; De Vos, Paul; Heylen, Kim

2016-01-19

Firmicutes have the capacity to remove excess nitrate from the environment via either denitrification, dissimilatory nitrate reduction to ammonium or both. The recent renewed interest in their nitrogen metabolism has revealed many interesting features, the most striking being their wide variety of dissimilatory nitrate reduction pathways. In the present study, nitrous oxide production from Bacillus licheniformis, a ubiquitous Gram-positive, spore-forming species with many industrial applications, is investigated. B. licheniformis has long been considered a denitrifier but physiological experiments on three different strains demonstrated that nitrous oxide is not produced from nitrate in stoichiometric amounts, rather ammonium is the most important end-product, produced during fermentation. Significant strain dependency in end-product ratios, attributed to nitrite and ammonium, and medium dependency in nitrous oxide production were also observed. Genome analyses confirmed the lack of a nitrite reductase to nitric oxide, the key enzyme of denitrification. Based on the gene inventory and building on knowledge from other non-denitrifying nitrous oxide emitters, hypothetical pathways for nitrous oxide production, involving NarG, NirB, qNor and Hmp, are proposed. In addition, all publically available genomes of B. licheniformis demonstrated similar gene inventories, with specific duplications of the nar operon, narK and hmp genes as well as NarG phylogeny supporting the evolutionary separation of previously described distinct BALI1 and BALI2 lineages. Using physiological and genomic data we have demonstrated that the common soil bacterium B. licheniformis does not denitrify but is capable of fermentative dissimilatory nitrate/nitrite reduction to ammonium (DNRA) with concomitant production of N2O. Considering its ubiquitous nature and non-fastidious growth in the lab, B. licheniformis is a suitable candidate for further exploration of the actual mechanism of N2O

Ulipristal acetate versus leuprolide acetate for uterine fibroids.

Science.gov (United States)

Donnez, Jacques; Tomaszewski, Janusz; Vázquez, Francisco; Bouchard, Philippe; Lemieszczuk, Boguslav; Baró, Francesco; Nouri, Kazem; Selvaggi, Luigi; Sodowski, Krzysztof; Bestel, Elke; Terrill, Paul; Osterloh, Ian; Loumaye, Ernest

2012-02-02

The efficacy and side-effect profile of ulipristal acetate as compared with those of leuprolide acetate for the treatment of symptomatic uterine fibroids before surgery are unclear. In this double-blind noninferiority trial, we randomly assigned 307 patients with symptomatic fibroids and excessive uterine bleeding to receive 3 months of daily therapy with oral ulipristal acetate (at a dose of either 5 mg or 10 mg) or once-monthly intramuscular injections of leuprolide acetate (at a dose of 3.75 mg). The primary outcome was the proportion of patients with controlled bleeding at week 13, with a prespecified noninferiority margin of -20%. Uterine bleeding was controlled in 90% of patients receiving 5 mg of ulipristal acetate, in 98% of those receiving 10 mg of ulipristal acetate, and in 89% of those receiving leuprolide acetate, for differences (as compared with leuprolide acetate) of 1.2 percentage points (95% confidence interval [CI], -9.3 to 11.8) for 5 mg of ulipristal acetate and 8.8 percentage points (95% CI, 0.4 to 18.3) for 10 mg of ulipristal acetate. Median times to amenorrhea were 7 days for patients receiving 5 mg of ulipristal acetate, 5 days for those receiving 10 mg of ulipristal acetate, and 21 days for those receiving leuprolide acetate. Moderate-to-severe hot flashes were reported for 11% of patients receiving 5 mg of ulipristal acetate, for 10% of those receiving 10 mg of ulipristal acetate, and for 40% of those receiving leuprolide acetate (P<0.001 for each dose of ulipristal acetate vs. leuprolide acetate). Both the 5-mg and 10-mg daily doses of ulipristal acetate were noninferior to once-monthly leuprolide acetate in controlling uterine bleeding and were significantly less likely to cause hot flashes. (Funded by PregLem; ClinicalTrials.gov number, NCT00740831.).

Inhibitory Effect of Gamma-Irradiated Chitosan on the Growth of Denitrifiers

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Javier Vilcáez

2009-01-01

Full Text Available In order to find an environmentally benign substitute to hazardous inhibitory agents, the inhibitory effect of -irradiated chitosans against a mixed culture of denitrifying bacteria was experimentally evaluated. Unlike other studies using pure aerobic cultures, the observed effect was not a complete inhibition but a transient inhibition reflected by prolonged lag phases and reduced growth rates. Raw chitosan under acid conditions (pH 6.3 exerted the strongest inhibition followed by the 100 kGy and 500 kGy irradiated chitosans, respectively. Therefore, because the molecular weight of chitosan decreases with the degree of -irradiation, the inhibitory properties of chitosan due to its high molecular weight were more relevant than the inhibitory properties gained due to the modification of the surface charge and/or chemical structure by -irradiation. High dosage of -irradiated appeared to increase the growth of mixed denitrifying bacteria in acid pH media. However, in neutral pH media, high dosage of -irradiation appeared to enhance the inhibitory effect of chitosan.

Optimum O2:CH4 Ratio Promotes the Synergy between Aerobic Methanotrophs and Denitrifiers to Enhance Nitrogen Removal

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Jing Zhu

2017-06-01

Full Text Available The O2:CH4 ratio significantly effects nitrogen removal in mixed cultures where aerobic methane oxidation is coupled with denitrification (AME-D. The goal of this study was to investigate nitrogen removal of the AME-D process at four different O2:CH4 ratios [0, 0.05, 0.25, and 1 (v/v]. In batch tests, the highest denitrifying activity was observed when the O2:CH4 ratio was 0.25. At this ratio, the methanotrophs produced sufficient carbon sources for denitrifiers and the oxygen level did not inhibit nitrite removal. The results indicated that the synergy between methanotrophs and denitrifiers was significantly improved, thereby achieving a greater capacity of nitrogen removal. Based on thermodynamic and chemical analyses, methanol, butyrate, and formaldehyde could be the main trophic links of AME-D process in our study. Our research provides valuable information for improving the practical application of the AME-D systems.

Metagenomic Insights into Evolution of a Heavy Metal-Contaminated Groundwater Microbial Community

Energy Technology Data Exchange (ETDEWEB)

Hemme, Christopher L.; Deng, Ye; Gentry, Terry J.; Fields, Matthew W.; Wu, Liyou; Barua, Soumitra; Barry, Kerrie; Tringe, Susannah G.; Watson, David B.; He, Zhili; Hazen, Terry C.; Tiedje, James M.; Rubin, Edward M.; Zhou, Jizhong

2010-02-15

Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents (~;;50 years) have resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic diversity. Although the surviving microbial community possesses all metabolic pathways necessary for survival and growth in such an extreme environment, its structure is very simple, primarily composed of clonal denitrifying ?- and ?-proteobacterial populations. The resulting community is over-abundant in key genes conferring resistance to specific stresses including nitrate, heavy metals and acetone. Evolutionary analysis indicates that lateral gene transfer could be a key mechanism in rapidly responding and adapting to environmental contamination. The results presented in this study have important implications in understanding, assessing and predicting the impacts of human-induced activities on microbial communities ranging from human health to agriculture to environmental management, and their responses to environmental changes.

Zinc deprivation of methanol fed anaerobic granular sludge bioreactors

NARCIS (Netherlands)

Fermoso, F.G.; Collins, G.; Bartacek, J.; Lens, P.N.L.

2008-01-01

The effect of omitting zinc from the influent of mesophilic (30 degrees C) methanol fed upflow anaerobic sludge bed (UASB) reactors, and latter zinc supplementation to the influent to counteract the deprivation, was investigated by coupling the UASB reactor performance to the microbial ecology of

Denitrifying capabilities of Tetrasphaera and their contribution towards nitrous oxide production in enhanced biological phosphorus removal processes.

Science.gov (United States)

Marques, Ricardo; Ribera-Guardia, Anna; Santos, Jorge; Carvalho, Gilda; Reis, Maria A M; Pijuan, Maite; Oehmen, Adrian

2018-06-15

Denitrifying enhanced biological phosphorus removal (EBPR) systems can be an efficient means of removing phosphate (P) and nitrate (NO 3 - ) with low carbon source and oxygen requirements. Tetrasphaera is one of the most abundant polyphosphate accumulating organisms present in EBPR systems, but their capacity to achieve denitrifying EBPR has not previously been determined. An enriched Tetrasphaera culture, comprising over 80% of the bacterial biovolume was obtained in this work. Despite the denitrification capacity of Tetrasphaera, this culture achieved only low levels of anoxic P-uptake. Batch tests with different combinations of NO 3 - , nitrite (NO 2 - ) and nitrous oxide (N 2 O) revealed lower N 2 O accumulation by Tetrasphaera as compared to Accumulibacter and Competibacter when multiple electron acceptors were added. Electron competition was observed during the addition of multiple nitrogen electron acceptors species, where P uptake appeared to be slightly favoured over glycogen production in these situations. This study increases our understanding of the role of Tetrasphaera-related organisms in denitrifying EBPR systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Simultaneous removal of sulfide, nitrate and acetate: Kinetic modeling

International Nuclear Information System (INIS)

Wang Aijie; Liu Chunshuang; Ren Nanqi; Han Hongjun; Lee Duujong

2010-01-01

Biological removal of sulfide, nitrate and chemical oxygen demand (COD) simultaneously from industrial wastewaters to elementary sulfur (S 0 ), N 2 , and CO 2 , or named the denitrifying sulfide (DSR) process, is a cost effective and environmentally friendly treatment process for high strength sulfide and nitrate laden organic wastewater. Kinetic model for the DSR process was established for the first time on the basis of Activated Sludge Model No. 1 (ASM1). The DSR experiments were conducted at influent sulfide concentrations of 200-800 mg/L, whose results calibrate the model parameters. The model correlates well with the DSR process dynamics. By introducing the switch function and the inhibition function, the competition between autotrophic and heterotrophic denitrifiers is quantitatively described and the degree of inhibition of sulfide on heterotrophic denitrifiers is realized. The model output indicates that the DSR reactor can work well at 0.5 1000 mg/L influent sulfide, however, the DSR system will break down.

Microbial Nitrogen-Cycle Gene Abundance in Soil of Cropland Abandoned for Different Periods.

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Huhe

Full Text Available In Inner Mongolia, steppe grasslands face desertification or degradation because of human overuse and abandonment after inappropriate agricultural management. The soils in these abandoned croplands exist in heterogeneous environments characterized by widely fluctuating microbial growth. Quantitative polymerase chain reaction analysis of microbial genes encoding proteins involved in the nitrogen cycle was used to study Azotobacter species, nitrifiers, and denitrifiers in the soils from steppe grasslands and croplands abandoned for 2, 6, and 26 years. Except for nitrifying archaea and nitrous oxide-reducing bacteria, the relative genotypic abundance of microbial communities involved in nitrogen metabolism differed by approximately 2- to 10-fold between abandoned cropland and steppe grassland soils. Although nitrogen-cycle gene abundances varied with abandonment time, the abundance patterns of nitrogen-cycle genes separated distinctly into abandoned cropland versus light-grazing steppe grassland, despite the lack of any cultivation for over a quarter-century. Plant biomass and plant diversity exerted a significant effect on the abundance of microbial communities that mediate the nitrogen cycle (P < 0.002 and P < 0.03, respectively. The present study elucidates the ecology of bacteria that mediate the nitrogen cycle in recently abandoned croplands.

Acetate biostimulation as an effective treatment for cleaning up alkaline soil highly contaminated with Cr(VI).

Science.gov (United States)

Lara, Paloma; Morett, Enrique; Juárez, Katy

2017-11-01

Stimulation of microbial reduction of Cr(VI) to the less toxic and less soluble Cr(III) through electron donor addition has been regarded as a promising approach for the remediation of chromium-contaminated soil and groundwater sites. However, each site presents different challenges; local physicochemical characteristics and indigenous microbial communities influence the effectiveness of the biostimulation processes. Here, we show microcosm assays stimulation of microbial reduction of Cr(VI) in highly alkaline and saline soil samples from a long-term contaminated site in Guanajuato, Mexico. Acetate was effective promoting anaerobic microbial reduction of 15 mM of Cr(VI) in 25 days accompanied by an increase in pH from 9 to 10. Our analyses showed the presence of Halomonas, Herbaspirillum, Nesterenkonia/Arthrobacter, and Bacillus species in the soil sample collected. Moreover, from biostimulated soil samples, it was possible to isolate Halomonas spp. strains able to grow at 32 mM of Cr(VI). Additionally, we found that polluted groundwater has bacterial species different to those found in soil samples with the ability to resist and reduce chromate using acetate and yeast extract as electron donors.

The stable carbon isotope biogeochemistry of acetate and other dissolved carbon species in deep subseafloor sediments at the northern Cascadia Margin

Science.gov (United States)

Heuer, Verena B.; Pohlman, John W.; Torres, Marta E.; Elvert, Marcus; Hinrichs, Kai-Uwe

2009-01-01

Ocean drilling has revealed the existence of vast microbial populations in the deep subseafloor, but to date little is known about their metabolic activities. To better understand the biogeochemical processes in the deep biosphere, we investigate the stable carbon isotope chemistry of acetate and other carbon-bearing metabolites in sediment pore-waters. Acetate is a key metabolite in the cycling of carbon in anoxic sediments. Its stable carbon isotopic composition provides information on the metabolic processes dominating acetate turnover in situ. This study reports our findings for a methane-rich site at the northern Cascadia Margin (NE Pacific) where Expedition 311 of the Integrated Ocean Drilling Program (IODP) sampled the upper 190 m of sediment. At Site U1329, δ13C values of acetate span a wide range from −46.0‰ to −11.0‰ vs. VPDB and change systematically with sediment depth. In contrast, δ13C values of both the bulk dissolved organic carbon (DOC) (−21.6 ± 1.3‰ vs. VPDB) and the low-molecular-weight compound lactate (−20.9 ± 1.8‰ vs. VPDB) show little variability. These species are interpreted to represent the carbon isotopic composition of fermentation products. Relative to DOC, acetate is up to 23.1‰ depleted and up to 9.1‰ enriched in 13C. Broadly, 13C-depletions of acetate relative to DOC indicate flux of carbon from acetogenesis into the acetate pool while 13C-enrichments of pore-water acetate relative to DOC suggest consumption of acetate by acetoclastic methanogenesis. Isotopic relationships between acetate and lactate or DOC provide new information on the carbon flow and the presence and activity of specific functional microbial communities in distinct biogeochemical horizons of the sediment. In particular, they suggest that acetogenic CO2-reduction can coexist with methanogenic CO2-reduction, a notion contrary to the hypothesis that hydrogen levels are controlled by the thermodynamically most favorable electron

Biotechnological applications of acetic acid bacteria.

Science.gov (United States)

Raspor, Peter; Goranovic, Dusan

2008-01-01

The acetic acid bacteria (AAB) have important roles in food and beverage production, as well as in the bioproduction of industrial chemicals. In recent years, there have been major advances in understanding their taxonomy, molecular biology, and physiology, and in methods for their isolation and identification. AAB are obligate aerobes that oxidize sugars, sugar alcohols, and ethanol with the production of acetic acid as the major end product. This special type of metabolism differentiates them from all other bacteria. Recently, the AAB taxonomy has been strongly rearranged as new techniques using 16S rRNA sequence analysis have been introduced. Currently, the AAB are classified in ten genera in the family Acetobacteriaceae. AAB can not only play a positive role in the production of selected foods and beverages, but they can also spoil other foods and beverages. AAB occur in sugar- and alcohol-enriched environments. The difficulty of cultivation of AAB on semisolid media in the past resulted in poor knowledge of the species present in industrial processes. The first step of acetic acid production is the conversion of ethanol from a carbohydrate carried out by yeasts, and the second step is the oxidation of ethanol to acetic acid carried out by AAB. Vinegar is traditionally the product of acetous fermentation of natural alcoholic substrates. Depending on the substrate, vinegars can be classified as fruit, starch, or spirit substrate vinegars. Although a variety of bacteria can produce acetic acid, mostly members of Acetobacter, Gluconacetobacter, and Gluconobacter are used commercially. Industrial vinegar manufacturing processes fall into three main categories: slow processes, quick processes, and submerged processes. AAB also play an important role in cocoa production, which represents a significant means of income for some countries. Microbial cellulose, produced by AAB, possesses some excellent physical properties and has potential for many applications. Other

Plastic biofilm carrier after corn cobs reduces nitrate loading in laboratory denitrifying bioreactors

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Nitrate-nitrogen removal rates can be increased substantially in denitrifying bioreactors with a corn cob bed medium compared to woodchips; however, additional organic carbon (C) is released into the effluent. This laboratory column experiment was conducted to test the performance of a post-bed cha...

Role of a Bacillus subtilis Direct-Fed Microbial on Digesta Viscosity, Bacterial Translocation, and Bone Mineralization in Turkey Poults Fed with a Rye-Based Diet.

Science.gov (United States)

Latorre, Juan D; Hernandez-Velasco, Xochitl; Kogut, Michael H; Vicente, Jose L; Wolfenden, Ross; Wolfenden, Amanda; Hargis, Billy M; Kuttappan, Vivek A; Tellez, Guillermo

2014-01-01

Rye contains high concentrations of non-starch polysaccharides (NSPs), leading to reduced digestibility. Since poultry have little or no endogenous enzymes capable of hydrolyzing these NSP, exogenous carbohydrases as feed additives are used in an attempt to reduce the anti-nutritional effects of these polysaccharides. Previously, an in vitro study conducted in our laboratory showed that inclusion of certain Bacillus direct-fed microbial (DFM) candidates that produce exogenous phytase, lipase, protease, cellulase, and xylanase in high-NSP diets significantly reduced both digesta viscosity and Clostridium perfringens proliferation. In the present study, rye-based turkey starter diets with or without Bacillus-DFM were administered ad libitum to day-of-hatch turkey poults in two independent experiments. In both experiments, day-of-hatch turkey poults were randomly assigned to either a control diet (CON) or a DFM treated diet (n = 25 birds/group). At 10 days-of-age, all turkey poults from experiments 1 and 2 were weighted and 12 turkey poults/group were randomly selected and humanely killed. Liver samples were aseptically collected to evaluate bacterial translocation, and intestinal digesta samples were individually collected to evaluate viscosity. Additionally, in experiment 2 both tibias were removed for assessment of bone parameters. In both experiments, the treated group showed a reduction in the total number of coliforms in the liver and a reduced digesta viscosity when compared to the CON group (P content, calcium content, and phosphorus content when compared with CON turkey poults. In summary, turkey poults fed with a rye-based diet without DFM showed an increase in bacterial translocation and digesta viscosity, accompanied by a reduction in bone mineralization; however, these adverse effects can be prevented by the inclusion of selected a Bacillus-DFM candidate in high-NSP diets.

Gammarus-Microbial Interactions: A Review

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Daniel Nelson

2011-01-01

Full Text Available Gammarus spp. are typically classified as shredders under the functional feeding group classification. In the wild and in the laboratory, Gammarus spp. will often shred leaves, breaking them down into finer organic matter fractions. However, leaf litter is a poor quality food source (i.e., high C : N and C : P ratios and very little leaf material is assimilated by shredders. In freshwater habitats leaf litter is colonized rapidly (within ∼1-2 weeks by aquatic fungi and bacteria, making the leaves more palatable and nutritious to consumers. Several studies have shown that Gammarus spp. show preference for conditioned leaves over nonconditioned leaves and certain fungal species to others. Furthermore, Gammarus spp. show increased survival and growth rates when fed conditioned leaves compared to non-conditioned leaves. Thus, Gammarus spp. appear to rely on the microbial biofilm associated with leaf detritus as a source of carbon and/or essential nutrients. Also, Gammarus spp. can have both positive and negative effects on the microbial communities on which they fed, making them an important component of the microbial loop in aquatic ecosystems.

Microbial catabolic activities are naturally selected by metabolic energy harvest rate.

Science.gov (United States)

González-Cabaleiro, Rebeca; Ofiţeru, Irina D; Lema, Juan M; Rodríguez, Jorge

2015-12-01

The fundamental trade-off between yield and rate of energy harvest per unit of substrate has been largely discussed as a main characteristic for microbial established cooperation or competition. In this study, this point is addressed by developing a generalized model that simulates competition between existing and not experimentally reported microbial catabolic activities defined only based on well-known biochemical pathways. No specific microbial physiological adaptations are considered, growth yield is calculated coupled to catabolism energetics and a common maximum biomass-specific catabolism rate (expressed as electron transfer rate) is assumed for all microbial groups. Under this approach, successful microbial metabolisms are predicted in line with experimental observations under the hypothesis of maximum energy harvest rate. Two microbial ecosystems, typically found in wastewater treatment plants, are simulated, namely: (i) the anaerobic fermentation of glucose and (ii) the oxidation and reduction of nitrogen under aerobic autotrophic (nitrification) and anoxic heterotrophic and autotrophic (denitrification) conditions. The experimentally observed cross feeding in glucose fermentation, through multiple intermediate fermentation pathways, towards ultimately methane and carbon dioxide is predicted. Analogously, two-stage nitrification (by ammonium and nitrite oxidizers) is predicted as prevailing over nitrification in one stage. Conversely, denitrification is predicted in one stage (by denitrifiers) as well as anammox (anaerobic ammonium oxidation). The model results suggest that these observations are a direct consequence of the different energy yields per electron transferred at the different steps of the pathways. Overall, our results theoretically support the hypothesis that successful microbial catabolic activities are selected by an overall maximum energy harvest rate.

Biological acetate production from carbon dioxide by Acetobacterium woodii and Clostridium ljungdahlii: The effect of cell immobilization.

Science.gov (United States)

Cheng, Hai-Hsuan; Syu, Jyun-Cyuan; Tien, Shih-Yuan; Whang, Liang-Ming

2018-08-01

This study investigated the acetate production from gas mixture of hydrogen (H 2 ) and carbon dioxide (CO 2 ) in the ratio of 7:3 using two acetogens: Acetobacterium woodii and Clostridium ljungdahlii. Batch result shows A. woodii performed two-phase degradation with the presence of glucose that lactate was produced from glucose and was reutilized for the production of butyrate and few acetate, while only acetate was detected when providing gas mixture. C. ljungdahlii produced butyrate and ethanol along with acetate when glucose was introduced, while only ethanol and acetate were found by feeding gas mixture. The acetate-to-ethanol (A/E) ratio can be enhanced by cell immobilization, while GAC immobilization produced only acetate and the production rate reached 0.072 mmol/d under fed-batch operation. Acetate production rate increased from 18 to 28 mmol/L/d with GAC immobilization when gas flowrate increased from 100 to 300 mL/min in anaerobic fluidized membrane bioreactor (AFMBR), and a highest A/E ratio of 30 implies the possible application of acetate recovery from H 2 and CO 2 . Copyright © 2018 Elsevier Ltd. All rights reserved.

Microbial dynamics in upflow anaerobic sludge blanket (UASB) bioreactor granules in response to short-term changes in substrate feed

Energy Technology Data Exchange (ETDEWEB)

Kovacik, William P.; Scholten, Johannes C.; Culley, David E.; Hickey, Robert; Zhang, Weiwen; Brockman, Fred J.

2010-08-01

The complexity and diversity of the microbial communities in biogranules from an upflow anaerobic sludge blanket (UASB) bioreactor were determined in response to short-term changes in substrate feeds. The reactor was fed simulated brewery wastewater (SBWW) (70% ethanol, 15% acetate, 15% propionate) for 1.5 months (phase 1), acetate / sulfate for 2 months (phase 2), acetate-alone for 3 months (phase 3), and then a return to SBWW for 2 months (phase 4). Performance of the reactor remained relatively stable throughout the experiment as shown by COD removal and gas production. 16S rDNA, methanogen-associated mcrA and sulfate reducer-associated dsrAB genes were PCR amplified, then cloned and sequenced. Sequence analysis of 16S clone libraries showed a relatively simple community composed mainly of the methanogenic Archaea (Methanobacterium and Methanosaeta), members of the Green Non-Sulfur (Chloroflexi) group of Bacteria, followed by fewer numbers of Syntrophobacter, Spirochaeta, Acidobacteria and Cytophaga-related Bacterial sequences. Methanogen-related mcrA clone libraries were dominated throughout by Methanobacter and Methanospirillum related sequences. Although not numerous enough to be detected in our 16S rDNA libraries, sulfate reducers were detected in dsrAB clone libraries, with sequences related to Desulfovibrio and Desulfomonile. Community diversity levels (Shannon-Weiner index) generally decreased for all libraries in response to a change from SBWW to acetate-alone feed. But there was a large transitory increase noted in 16S diversity at the two-month sampling on acetate-alone, entirely related to an increase in Bacterial diversity. Upon return to SBWW conditions in phase 4, all diversity measures returned to near phase 1 levels.

Effects of potato fiber and potato-resistant starch on biomarkers of colonic health in rats fed diets containing red meat.

Science.gov (United States)

Paturi, Gunaranjan; Nyanhanda, Tafadzwa; Butts, Christine A; Herath, Thanuja D; Monro, John A; Ansell, Juliet

2012-10-01

The effects of red meat consumption with and without fermentable carbohydrates on indices of large bowel health in rats were examined. Sprague-Dawley rats were fed cellulose, potato fiber, or potato-resistant starch diets containing 12% casein for 2 wk, then similar diets containing 25% cooked beef for 6 wk. After week 8, cecal and colonic microbiota composition, fermentation end-products, colon structure, and colonocyte DNA damage were analyzed. Rats fed potato fiber had lower Bacteroides-Prevotella-Porphyromonas group compared to other diet groups. Colonic Bifidobacterium spp. and/or Lactobacillus spp. were higher in potato fiber and potato-resistant starch diets than in the cellulose diet. Beneficial changes were observed in short-chain fatty acid concentrations (acetic, butyric, and propionic acids) in rats fed potato fiber compared with rats fed cellulose. Phenol and p-cresol concentrations were lower in the cecum and colon of rats fed potato fiber. An increase in goblet cells per crypt and longer crypts were found in the colon of rats fed potato fiber and potato-resistant starch diets. Fermentable carbohydrates had no effect on colonic DNA damage. Dietary combinations of red meat with potato fiber or potato-resistant starch have distinctive effects in the large bowel. Future studies are essential to examine the efficacy of different types of nondigestible carbohydrates in maintaining colonic health during long-term consumption of high-protein diets. Improved understanding of interactions between the food consumed and gut microbiota provides knowledge needed to make healthier food choices for large bowel health. The impact of red meat on large bowel health may be ameliorated by consuming with fermentable dietary fiber, a colonic energy source that produces less harmful by-products than the microbial breakdown of colonic protein for energy. Developing functional red meat products with fermentable dietary fiber could be one way to promote a healthy and balanced

A preliminary study of anaerobic thiosulfate-oxidising bacteria as denitrifiers in the Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

LokaBharathi, P.A.; Chandramohan, D.; Nair, S.

Bacteria which oxidize thiosulfate and reduce nitrate (TONRB) and bacteria which oxidize thiosulfate and denitrify (TODB) sampled at 5-, 100-, 200-and 300-m depths were enumerated in agar shake cultures by colony counting and by applying MPN...

Microbial Community Pathways for the Production of Volatile Fatty Acids From CO2 and Electricity

Directory of Open Access Journals (Sweden)

Jorge Wenzel

2018-04-01

Full Text Available This study aims at elucidating the metabolic pathways involved in the production of volatile fatty acids from CO2 and electricity. Two bioelectrochemical systems (BES were fed with pure CO2 (cells A and B. The cathode potential was first poised at −574 mV vs. standard hydrogen electrode (SHE and then at −756 mV vs. SHE in order to ensure the required reducing power. Despite applying similar operation conditions to both BES, they responded differently. A mixture of organic compounds (1.87 mM acetic acid, 2.30 mM formic acid, 0.43 mM propionic acid, 0.15 mM butyric acid, 0.55 mM valeric acid, and 0.62 mM ethanol was produced in cell A while mainly 1.82 mM acetic acid and 0.23 mM propionic acid were produced in cell B. The microbial community analysis performed by 16S rRNA gene pyrosequencing showed a predominance of Clostridium sp. and Serratia sp. in cell A whereas Burkholderia sp. and Xanthobacter sp. predominated in cell B. The coexistence of three metabolic pathways involved in carbon fixation was predicted. Calvin cycle was predicted in both cells during the whole experiment while Wood-Ljungdahl and Arnon-Buchanan pathways predominated in the period with higher coulombic efficiency. Metabolic pathways which transform organic acids into anabolic intermediaries were also predicted, indicating the occurrence of complex trophic interactions. These results further complicate the understanding of these mixed culture microbial processes but also expand the expectation of compounds that could potentially be produced with this technology.

Pseudomonads Isolated from Pristine Background Groundwater Proliferate More Effectively in Co-culture than in Monoculture Under Denitrifying Conditions

Science.gov (United States)

Aaring, A. B.; Lancaster, A.; Novichkov, P.; Adams, M. W. W.; Deutschbauer, A. M.; Chakraborty, R.

2016-12-01

As part of the Ecosystems and Networks Integrated with Genes and Molecular Assemblies (ENIGMA) consortium, we study the microbial community at the U.S. Department of Energy's Field Research Center (FRC) in Oak Ridge. The groundwater at this site contains plumes of nitrate with concentrations up to 14,000mg/L among other contaminants, though molybdenum concentrations are low. Because molybdenum is essential to nitrate reduction, this can be inhibitory to growth. Several strains of Pseudomonas were isolated from the same background groundwater sample. These isolates utilized diverse carbon sources ranging from acetate to glucose while growing under denitrifying conditions. The strains were also screened for nitrate tolerance and a couple of them were shown to be tolerant to 300-400 mM nitrate under anaerobic conditions. In the field site the bacteria live in consortia rather than in isolation, therefore we hypothesized that growth of these strains will be more robust in co-culture, as the denitrification pathway was segmented between the species. Three of the isolates (Pseudomonas fluorescens strains N1B4, N2E2, N2E3) were selected for in-depth analysis based on growth in pairwise co-cultures relative to monocultures, and the availability of the relevant genetic tools, such as transposon mutant libraries. Full genome sequencing showed that strain N2E3 has a truncated dentrification pathway: it lacks nitrous oxide reductase. Our results show strain N2E2 grow to maximum cell density an average of 45 hours more quickly when grown with strain N2E3 than in monoculture. Utilizing RB-TnSeq libraries of our strains, it was also found that some genes involved in nitrate reduction, sulfate permeability, molybdenum utilization, and anaerobic reduction are important for growth under these conditions. In addition, a few unexpected genes were also shown to be positively correlated to growth, such as genes homologous to genes for DNA proofreading or antibiotic production. These

Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system

Science.gov (United States)

Ohtomo, Y.; Ijiri, A.; Ikegawa, Y.; Tsutsumi, M.; Imachi, H.; Uramoto, G.; Hoshino, T.; Morono, Y.; Tanikawa, W.; Hirose, T.; Inagaki, F.

2013-12-01

belonged to a methylotrophic methanogen within the genus Methanosarcina. For the acetate-fed culture, no cell proliferation and methane-production were observed after two-years incubation. During the injection of CO2 and fluid, increase of dissolved CH4 concentration was observed, of which δ13CCH4 were constantly similar to those of the absorbed coal-bed methane (δ13CCBM, ~70‰), suggesting the enhanced gas recovery with fluid flow. The output volume of CO2 (ΣCO2out, 22.1 to 125.6 mM) was smaller than initial concentration (ΣCO2in, 138.38 mM), which can be explained by either adsorption on coal, formation of carbonate minerals, or microbial consumption. Increase of acetate concentration in the fluids was also observed, whereas δ13Cacetate depleted during experiment. Considering with the decrease of additive H2, it is most likely that homo-acetogenesis would occur during experiments, which is consistent with detection of Sporomusa-related 16S rRNA genes, homo-acetogenic bacterium, in cloning analysis of sandstone after experiment. Decrease of formate concentrations and increase of δ13Cformate indicate bacterial consumption of formate and isotopic fractionation. Our results suggest that CO2 injection to natural coal-sand formation stimulates homo-acetogenesis rather than methanogenesis, accompanied by biogenic CO2 conversion to acetate.

High cell density fed-batch fermentations for lipase production: feeding strategies and oxygen transfer.

Science.gov (United States)

Salehmin, M N I; Annuar, M S M; Chisti, Y

2013-11-01

This review is focused on the production of microbial lipases by high cell density fermentation. Lipases are among the most widely used of the enzyme catalysts. Although lipases are produced by animals and plants, industrial lipases are sourced almost exclusively from microorganisms. Many of the commercial lipases are produced using recombinant species. Microbial lipases are mostly produced by batch and fed-batch fermentation. Lipases are generally secreted by the cell into the extracellular environment. Thus, a crude preparation of lipases can be obtained by removing the microbial cells from the fermentation broth. This crude cell-free broth may be further concentrated and used as is, or lipases may be purified from it to various levels. For many large volume applications, lipases must be produced at extremely low cost. High cell density fermentation is a promising method for low-cost production: it allows a high concentration of the biomass and the enzyme to be attained rapidly and this eases the downstream recovery of the enzyme. High density fermentation enhances enzyme productivity compared with the traditional submerged culture batch fermentation. In production of enzymes, a high cell density is generally achieved through fed-batch operation, not through perfusion culture which is cumbersome. The feeding strategies used in fed-batch fermentations for producing lipases and the implications of these strategies are discussed. Most lipase-producing microbial fermentations require oxygen. Oxygen transfer in such fermentations is discussed.

Diversity of archaea and bacteria in a biogas reactor fed with ...

African Journals Online (AJOL)

Diversity of archaea and bacteria in a biogas reactor fed with Pennisetum sinese ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING ... rumen microbial community in a biogas reactor by 16S rRNA gene analysis, ...

Simultaneous removal of sulfide, nitrate and acetate: Kinetic modeling

Energy Technology Data Exchange (ETDEWEB)

Wang Aijie, E-mail: waj0578@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090 (China); Liu Chunshuang; Ren Nanqi; Han Hongjun [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090 (China); Lee Duujong [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090 (China); Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2010-06-15

Biological removal of sulfide, nitrate and chemical oxygen demand (COD) simultaneously from industrial wastewaters to elementary sulfur (S{sup 0}), N{sub 2}, and CO{sub 2}, or named the denitrifying sulfide (DSR) process, is a cost effective and environmentally friendly treatment process for high strength sulfide and nitrate laden organic wastewater. Kinetic model for the DSR process was established for the first time on the basis of Activated Sludge Model No. 1 (ASM1). The DSR experiments were conducted at influent sulfide concentrations of 200-800 mg/L, whose results calibrate the model parameters. The model correlates well with the DSR process dynamics. By introducing the switch function and the inhibition function, the competition between autotrophic and heterotrophic denitrifiers is quantitatively described and the degree of inhibition of sulfide on heterotrophic denitrifiers is realized. The model output indicates that the DSR reactor can work well at 0.5 < C/S < 3.0 with influent sulfide concentration of 400-1000 mg/L. At >1000 mg/L influent sulfide, however, the DSR system will break down.

Submerged macrophytes shape the abundance and diversity of bacterial denitrifiers in bacterioplankton and epiphyton in the Shallow Fresh Lake Taihu, China.

Science.gov (United States)

Fan, Zhou; Han, Rui-Ming; Ma, Jie; Wang, Guo-Xiang

2016-07-01

nirK and nirS genes are important functional genes involved in the denitrification pathway. Recent studies about these two denitrifying genes are focusing on sediment and wastewater microbe. In this study, we conducted a comparative analysis of the abundance and diversity of denitrifiers in the epiphyton of submerged macrophytes Potamogeton malaianus and Ceratophyllum demersum as well as in bacterioplankton in the shallow fresh lake Taihu, China. Results showed that nirK and nirS genes had significant different niches in epiphyton and bacterioplankton. Bacterioplankton showed greater abundance of nirK gene in terms of copy numbers and lower abundance of nirS gene. Significant difference in the abundance of nirK and nirS genes also existed between the epiphyton from different submerged macrophytes. Similar community diversity yet different community abundance was observed between epiphytic bacteria and bacterioplankton. No apparent seasonal variation was found either in epiphytic bacteria or bacterioplankton; however, environmental parameters seemed to have direct relevancy with nirK and nirS genes. Our study suggested that submerged macrophytes have greater influence than seasonal parameters in shaping the presence and abundance of bacterial denitrifiers. Further investigation needs to focus on the potential contact and relative contribution between denitrifiers and environmental factors.

Relative rates of nitric oxide and nitrous oxide production by nitrifiers, denitrifiers, and nitrate respirers

Science.gov (United States)

Anderson, I. C.; Levine, J. S.

1986-01-01

An account is given of the atmospheric chemical and photochemical effects of biogenic nitric and nitrous oxide emissions. The magnitude of the biogenic emission of NO is noted to remain uncertain. Possible soil sources of NO and N2O encompass nitrification by autotropic and heterotropic nitrifiers, denitrification by nitrifiers and denitrifiers, nitrate respiration by fermenters, and chemodenitrification. Oxygen availability is the primary determinant of these organisms' relative rates of activity. The characteristics of this major influence are presently investigated in light of the effect of oxygen partial pressure on NO and N2O production by a wide variety of common soil-nitrifying, denitrifying, and nitrate-respiring bacteria under laboratory conditions. The results obtained indicate that aerobic soils are primary sources only when there is sufficient moisture to furnish anaerobic microsites for denitrification.

Nuclear techniques to determine microbial protein synthesis and productive performance of barki lambs fed rations containing some medicinal plants

International Nuclear Information System (INIS)

Mohamed, M.M.S.

2009-01-01

This study included two experiments, the first experiment was carried out in vitro to evaluate the effect of adding two levels of Lemongrass or Rosemary in ruminant rations on microbial protein synthesis using radio active sulfur S 35 . While, the second experiment was to study the effect of Lemongrass (CC) and Rosemary (RO) as feed additives in rations of lambs on feed intake, nutrient digestibility, some parameters of blood and rumen activity. Meanwhile, body weight and economical efficiency were studied. Twenty five of Barki male lambs with average body weight of 19.8 kg ± 1 kg and 3- 4 months of age were divided into 5 similar groups (5 lambs each). The first group (control) (R1) was fed on a concentrate feed mixture (CFM) plus rice straw (RS). While, R2 and R3 were fed as R1 ration supplemented with 100 or 200 mg Lemongrass /kg LBW/d respectively. Meantime, R4 and R5 were fed as R1 ration supplemented with 100 or 200 mg Rosemary /kg LBW/d respectively.The results indicated that more microbial protein synthesis was noticed with 4 mg of Lemongrass followed by 2 mg Rosemary, 2 mg Lemongrass and control which was higher than 4 mg Rosemary/ 0.5 g concentrate mixture. The differences were not statistically significant. The dry matter intake (DMI) was not significantly different for R4 and R3 when compared with R1 (control) and it significantly decreased in R5 and R2 compared with R1. The digestibilities of DM, OM, CP, EE and NFE in the supplemented groups were not significantly differing compared with R1. The digestibility of CF was significantly increased in R2 and R4 compared with R1 and there were no significant differences for R3 and R5 compared with R1. There were no significant differences in nutritive values as TDN, DCP and SV among all supplemented groups compared with R1. Rumen liquor TVFA,s was not significantly differ at zero time, but it decreased at 3 h and 6 h with all additives compared with the control with no significant differences among all

Reactor staging influences microbial community composition and diversity of denitrifying MBBRs- Implications on pharmaceutical removal

DEFF Research Database (Denmark)

Torresi, Elena; Gülay, Arda; Polesel, Fabio

2018-01-01

The subdivision of biofilm reactor in two or more stages (i.e., reactor staging) represents an option for process optimisation of biological treatment. In our previous work, we showed that the gradient of influent organic substrate availability (induced by the staging) can influence the microbial...

Influence of Bicarbonate, Sulfate, and Electron Donors on Biological reduction of Uranium and Microbial Community Composition

Energy Technology Data Exchange (ETDEWEB)

Luo, Wensui [ORNL; Zhou, Jizhong [ORNL; Wu, Weimin [ORNL; Yan, Tingfen [ORNL; Criddle, Craig [ORNL; Jardine, Philip M [ORNL; Gu, Baohua [ORNL

2007-01-01

A microcosm study was performed to investigate the effect of ethanol and acetate on uranium(VI) biological reduction and microbial community changes under various geochemical conditions. Each microcosm contained an uranium-contaminated sediment (up to 2.8 g U/kg) suspended in buffer with bicarbonate at concentrations of either 1 mM or 40 mM and sulfate at either 1.1 or 3.2 mM. Ethanol or acetate was used as an electron donor. Results indicate that ethanol yielded in significantly higher U(VI) reduction rates than acetate. A low bicarbonate concentration (1 mM) was favored for U(VI) bioreduction to occur in sediments, but high concentrations of bicarbonate (40 mM) and sulfate (3.2 mM) decreased the reduction rates of U(VI). Microbial communities were dominated by species from the Geothrix genus and Proteobacteria phylum in all microcosms. However, species in the Geobacteraceae family capable of reducing U(VI) were significantly enriched by ethanol and acetate in low bicarbonate buffer. Ethanol increased the population of unclassified Desulfuromonales, while acetate increased the population of Desulfovibrio. Additionally, species in the Geobacteraceae family were not enriched in high bicarbonate buffer, but the Geothrix and the unclassified Betaproteobacteria species were enriched. This study concludes that ethanol could be a better electron donor than acetate for reducing U(VI) under given experimental conditions, and electron donor and geoundwater geochemistry alter microbial communities responsible for U(VI) reduction.

Influence of bicarbonate, sulfate, and electron donors on biological reduction of uranium and microbial community composition

Energy Technology Data Exchange (ETDEWEB)

Luo Wensui [Oak Ridge Inst. for Science and Education, TN (United States); Oak Ridge National Lab., TN (United States). Environmental Sciences Div.; Wu Wei-Min; Criddle, C.S. [Stanford Univ., CA (United States). Dept. of Civil and Environmental Engineering; Yan Tingfen [Oak Ridge Inst. for Science and Education, TN (United States); Jardine, P.M.; Gu Baohua [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.; Zhou Jizhong [Oklahoma Univ., Norman, OK (United States). Dept. of Botany and Microbiology

2007-12-15

A microcosm study was performed to investigate the effect of ethanol and acetate on uranium(VI) biological reduction and microbial community changes under various geochemical conditions. Each microcosm contained an uranium-contaminated sediment (up to 2.8 g U/kg) suspended in buffer with bicarbonate at concentrations of either 1 or 40 mM and sulfate at either 1.1 or 3.2 mM. Ethanol or acetate was used as an electron donor. Results indicate that ethanol yielded in significantly higher U(VI) reduction rates than acetate. A low bicarbonate concentration (1 mM) was favored for U(VI) bioreduction to occur in sediments, but high concentrations of bicarbonate (40 mM) and sulfate (3.2 mM) decreased the reduction rates of U(VI). Microbial communities were dominated by species from the Geothrix genus and Proteobacteria phylum in all microcosms. However, species in the Geobacteraceae family capable of reducing U(VI) were significantly enriched by ethanol and acetate in low-bicarbonate buffer. Ethanol increased the population of unclassified Desulfuromonales, while acetate increased the population of Desulfovibrio. Additionally, species in the Geobacteraceae family were not enriched in high-bicarbonate buffer, but the Geothrix and the unclassified Betaproteobacteria species were enriched. This study concludes that ethanol could be a better electron donor than acetate for reducing U(VI) under given experimental conditions, and electron donor and groundwater geochemistry alter microbial communities responsible for U(VI) reduction. (orig.)

Iron oxides alter methanogenic pathways of acetate in production water of high-temperature petroleum reservoir.

Science.gov (United States)

Pan, Pan; Hong, Bo; Mbadinga, Serge Maurice; Wang, Li-Ying; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

2017-09-01

Acetate is a key intermediate in anaerobic crude oil biodegradation and also a precursor for methanogenesis in petroleum reservoirs. The impact of iron oxides, viz. β-FeOOH (akaganéite) and magnetite (Fe 3 O 4 ), on the methanogenic acetate metabolism in production water of a high-temperature petroleum reservoir was investigated. Methane production was observed in all the treatments amended with acetate. In the microcosms amended with acetate solely about 30% of the acetate utilized was converted to methane, whereas methane production was stimulated in the presence of magnetite (Fe 3 O 4 ) resulting in a 48.34% conversion to methane. Methane production in acetate-amended, β-FeOOH (akaganéite)-supplemented microcosms was much faster and acetate consumption was greatly improved compared to the other conditions in which the stoichiometric expected amounts of methane were not produced. Microbial community analysis showed that Thermacetogenium spp. (known syntrophic acetate oxidizers) and hydrogenotrophic methanogens closely related to Methanothermobacter spp. were enriched in acetate and acetate/magnetite (Fe 3 O 4 ) microcosms suggesting that methanogenic acetate metabolism was through hydrogenotrophic methanogenesis fueled by syntrophic acetate oxidizers. The acetate/β-FeOOH (akaganéite) microcosms, however, differed by the dominance of archaea closely related to the acetoclastic Methanosaeta thermophila. These observations suggest that supplementation of β-FeOOH (akaganéite) accelerated the production of methane further, driven the alteration of the methanogenic community, and changed the pathway of acetate methanogenesis from hydrogenotrophic methanogenesis fueled by syntrophic acetate oxidizers to acetoclastic.

Draft Genome Sequence of an Active Heterotrophic Nitrifier-Denitrifier, Cupriavidus pauculus UM1

OpenAIRE

Putonti, Catherine; Polley, Nathaniel; Castignetti, Domenic

2018-01-01

ABSTRACT Here, we present the draft genome sequence of Cupriavidus pauculus UM1, a metal-resistant heterotrophic nitrifier-denitrifier capable of synthesizing nitrite from pyruvic oxime. The size of the genome is 7,402,815 bp with a GC content of 64.8%. This draft assembly consists of 38 scaffolds.

The impact of anode acclimation strategy on microbial electrolysis cell treating hydrogen fermentation effluent

DEFF Research Database (Denmark)

Li, Xiaohu; Zhang, Ruizhe; Qian, Yawei

2017-01-01

The impact of different anode acclimation methods for enhancing hydrogen production in microbial electrolysis cell (MEC) was investigated in this study. The anodes were first acclimated in microbial fuel cells using acetate, butyrate and corn stalk fermentation effluent (CSFE) as substrate before...

Isolation and Physiological Characterization of Psychrophilic Denitrifying Bacteria from Permanently Cold Arctic Fjord Sediments (Svalbard, Norway)

Science.gov (United States)

Canion, Andy; Prakash, Om; Green, Stefan J.; Jahnke, Linda; Kuypers, Marcel M. M.; Kostka, Joel E.

2013-01-01

A large proportion of reactive nitrogen loss from polar sediments is mediated by denitrification, but microorganisms mediating denitrification in polar environments remain poorly characterized. A combined approach of most-probable-number (MPN) enumeration, cultivation and physiological characterization was used to describe psychrophilic denitrifying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). A MPN assay showed the presence of 10(sup 3)-10(sup 6) cells of psychrophilic nitrate-respiring bacteria g(sup -1) of sediment. Fifteen strains within the Proteobacteria were isolated using a systematic enrichment approach with organic acids as electron donors and nitrate as an electron acceptor. Isolates belonged to five genera, including Shewanella, Pseudomonas, Psychromonas (Gammaproteobacteria), Arcobacter (Epsilonproteobacteria) and Herminiimonas (Betaproteobacteria). All isolates were denitrifiers, except Shewanella, which exhibited the capacity for dissimilatory nitrate reduction to ammonium (DNRA). Growth from 0 to 40 degC demonstrated that all genera except Shewanella were psychrophiles with optimal growth below 15 degC, and adaptation to low temperature was demonstrated as a shift from primarily C16:0 saturated fatty acids to C16:1 monounsaturated fatty acids at lower temperatures. This study provides the first targeted enrichment and characterization of psychrophilic denitrifying bacteria from polar sediments, and two genera, Arcobacter and Herminiimonas, are isolated for the first time from permanently cold marine sediments.

Effects of mechanical disintegration of activated sludge on the activity of nitrifying and denitrifying bacteria and phosphorus accumulating organisms.

Science.gov (United States)

Zubrowska-Sudol, Monika; Walczak, Justyna

2014-09-15

The purpose of the study was to analyse the impact of hydrodynamic disintegration of thickened excess activated sludge, performed at different levels of energy density (70, 140 and 210 kJ/L), on the activity of microorganisms involved in nutrient removal from wastewater, i.e. nitrifiers, denitrifiers and phosphorus accumulating organisms (PAOs). Ammonium and nitrogen utilisation rates and phosphorus release rates for raw and disintegrated sludge were determined using batch tests. The experiment also included: 1) analysis of organic and nutrient compound release from activated sludge flocs, 2) determination of the sludge disintegration degree (DD), and 3) evaluation of respiratory activity of the biomass by using the oxygen uptake rate (OUR) batch test. It was shown that the activity degree of the examined groups of microorganisms depended on energy density and related sludge disintegration degree, and that inactivation of individual groups of microorganisms occurred at different values of DD. Least resistant to the destruction of activated sludge flocs turned out to be phosphorus accumulating organisms, while the most resistant were denitrifiers. A decrease of 20-40% in PAO activity was noted already at DD equal to 3-5%. The threshold values of DD, after crossing which the inactivation of nitrifiers and denitrifiers occurred, were equal to 8% and 10%, respectively. At lesser DD values an increase in the activity of these groups of microorganisms was observed, averaging 20.2-41.7% for nitrifiers and 9.98-36.3% for denitrifiers. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Control of Microcystis spp. Bloom by Combining Indigenous Denitrifying Bacteria From Sutami Reservoir with Fimbristylis globulosa and Vetiveria zizanoides

Directory of Open Access Journals (Sweden)

Bayu Agung Prahardika

2013-04-01

Full Text Available The purpose of this research is to know the ability of polyculture macrophyte (Fimbristylis globulosa and Vetiveria zizanoides and the combination of both with consortium of indigenous denitrifying bacteria from Sutami reservoir that was added by Microcystis spp. or not to reduce the concentration of nitrate, dissolved phosphate and the carrying capacity of Microcystis spp. The experiment was done in a medium filled up with Sutami reservoir water enriched with 16 ppm of nitrate and 0.4 ppm of phosphate. The denitrifying bacteria used in this research were DR-14, DU-27-1, DU-30-1, DU-30-2, TA-8 and DU-27-4 isolated from Sutami reservoir. The treatments were incubated within 15 days. Microcystis spp. abundance was calculated every day, but the measurement of the concentration of nitrate and dissolved phosphate was done every six days. The results showed that both treatment and the combination of both macrophytes with a consortium of denitrifying indigenous bacteria were added or not either Microcystis able to reduce nitrate at 99% and 93-99% orthophosphoric. The combination of macrophytes with denitrifying indigenous bacterial consortium from Sutami reservoir was able to inhibit the carrying capacity of Microcystis spp. highest up to 47.87%. They could also significantly reduce the abundance of Microcystis from 107 cells/mL in earlier days of the treatment into 0.35x104 cells/mL after fifteen days of incubation.

Subsurface Nitrogen-Cycling Microbial Communities at Uranium Contaminated Sites in the Colorado River Basin

Science.gov (United States)

Cardarelli, E.; Bargar, J.; Williams, K. H.; Dam, W. L.; Francis, C.

2015-12-01

Throughout the Colorado River Basin (CRB), uranium (U) persists as a relic contaminant of former ore processing activities. Elevated solid-phase U levels exist in fine-grained, naturally-reduced zone (NRZ) sediments intermittently found within the subsurface floodplain alluvium of the following Department of Energy-Legacy Management sites: Rifle, CO; Naturita, CO; and Grand Junction, CO. Coupled with groundwater fluctuations that alter the subsurface redox conditions, previous evidence from Rifle, CO suggests this resupply of U may be controlled by microbially-produced nitrite and nitrate. Nitrification, the two-step process of archaeal and bacterial ammonia-oxidation followed by bacterial nitrite oxidation, generates nitrate under oxic conditions. Our hypothesis is that when elevated groundwater levels recede and the subsurface system becomes anoxic, the nitrate diffuses into the reduced interiors of the NRZ and stimulates denitrification, the stepwise anaerobic reduction of nitrate/nitrite to dinitrogen gas. Denitrification may then be coupled to the oxidation of sediment-bound U(IV) forming mobile U(VI), allowing it to resupply U into local groundwater supplies. A key step in substantiating this hypothesis is to demonstrate the presence of nitrogen-cycling organisms in U-contaminated, NRZ sediments from the upper CRB. Here we investigate how the diversity and abundances of nitrifying and denitrifying microbial populations change throughout the NRZs of the subsurface by using functional gene markers for ammonia-oxidation (amoA, encoding the α-subunit of ammonia monooxygenase) and denitrification (nirK, nirS, encoding nitrite reductase). Microbial diversity has been assessed via clone libraries, while abundances have been determined through quantitative polymerase chain reaction (qPCR), elucidating how relative numbers of nitrifiers (amoA) and denitrifiers (nirK, nirS) vary with depth, vary with location, and relate to uranium release within NRZs in sediment

Effect of citric acid and microbial phytase on serum enzyme activities ...

African Journals Online (AJOL)

Effect of citric acid and microbial phytase on serum enzyme activities and plasma minerals retention in broiler chicks. ... African Journal of Biotechnology ... An experiment was conducted to study the effect of microbial phytase supplementation and citric acid in broiler chicks fed corn-soybean meal base diets on enzyme ...

Bentonite. Geotechnical barrier and source for microbial life

International Nuclear Information System (INIS)

Matschiavelli, Nicole; Kluge, Sindy; Cherkouk, Andrea; Steglich, Jennifer

2017-01-01

Due to their properties, namely a high swelling capacity and a low hydraulic conductivity, Bentonites fulfil as geotechnical barrier a sealing and buffering function in the nuclear waste repository. Depending on the mineral composition Bentonites contain many suitable electron-donors and -acceptors, enabling potential microbial life. For the potential repository of highly radioactive waste the microbial mediated transformation of Bentonite could influence its properties as a barrier material. Microcosms were set up containing Bentonite and anaerobic synthetic Opalinus-clay-pore water solution under an N_2/CO_2-atmosphere to elucidate the microbial potential within selected Bentonites. Substrates like acetate and lactate were supplemented to stimulate potential microbial activity. First results show that bentonites represent a source for microbial life, demonstrated by the consumption of lactate and the formation of pyruvate. Furthermore, microbial iron-reduction was determined, which plays a crucial role in Betonite-transformation.

Bentonite. Geotechnical barrier and source for microbial life

Energy Technology Data Exchange (ETDEWEB)

Matschiavelli, Nicole; Kluge, Sindy; Cherkouk, Andrea [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). HZDR Young Investigator Group; Steglich, Jennifer

2017-06-01

Due to their properties, namely a high swelling capacity and a low hydraulic conductivity, Bentonites fulfil as geotechnical barrier a sealing and buffering function in the nuclear waste repository. Depending on the mineral composition Bentonites contain many suitable electron-donors and -acceptors, enabling potential microbial life. For the potential repository of highly radioactive waste the microbial mediated transformation of Bentonite could influence its properties as a barrier material. Microcosms were set up containing Bentonite and anaerobic synthetic Opalinus-clay-pore water solution under an N{sub 2}/CO{sub 2}-atmosphere to elucidate the microbial potential within selected Bentonites. Substrates like acetate and lactate were supplemented to stimulate potential microbial activity. First results show that bentonites represent a source for microbial life, demonstrated by the consumption of lactate and the formation of pyruvate. Furthermore, microbial iron-reduction was determined, which plays a crucial role in Betonite-transformation.

Effects of Misgurnus anguillicaudatus and Cipangopaludina cathayensis on Pollutant Removal and Microbial Community in Constructed Wetlands

Directory of Open Access Journals (Sweden)

Pengfei Li

2015-05-01

Full Text Available Aquatic animals play an important role in the energy flow and matter cycling in the wetland ecosystem. However, little is known about their effects on pollutant removal performance and microbial community in constructed wetlands. This work presents an initial attempt to investigate the effects of Misgurnus anguillicaudatus (loach and Cipangopaludina cathayensis (snail on nutrient removal performance and microbial community of constructed wetlands (CWs. Compared with a control group, CW microcosms with aquatic animals exhibited better pollutant removal performance. The removal efficiencies of total phosphorus (TP in the loach group were 13.1% higher than in the control group, and snails increased the ammonium removal most effectively. Moreover, the concentration of total organic carbon (TOC and TP in sediment significantly reduced with the addition of loaches and snails (p < 0.05, whereas the concentration of total nitrogen (TN showed an obvious increase with the addition of loaches. High-throughput sequencing showed a microbial community structure change. Loaches and snails in wetlands changed the microbial diversity, especially in the Proteobacteria and denitrifying community. Results suggested that benthic aquatic animals might play an important role in CW ecosystems.

Distribution of baroduric, psychrotrophic and culturable nitrifying and denitrifying bacteria in the Central Indian Basin

Digital Repository Service at National Institute of Oceanography (India)

LokaBharathi, P.A.; PradeepRam, A.S.; Nair, S.; Nath, B.N.; Chandramohan, D.

The abundance of baroduric, culturable nitrifying and denitrifying bacteria in the deep-sea cores of Central Indian Basin (CIB) at ca 5000 m depth was investigated. Analysis of 8 cores, sampled between 10 degrees 00 minutes S and 75 degrees 55...

Brazilian kefir: structure, microbial communities and chemical composition

Directory of Open Access Journals (Sweden)

Karina Teixeira Magalhães

2011-06-01

Full Text Available Microbial ecology and chemical composition of Brazilian kefir beverage was performed. The microorganisms associated with Brazilian kefir were investigated using a combination of phenotypic and genotypic methods. A total of 359 microbial isolates were identified. Lactic acid bacteria (60.5% were the major isolated group identified, followed by yeasts (30.6% and acetic acid bacteria (8.9%. Lactobacillus paracasei (89 isolates, Lactobacillus parabuchneri (41 isolates, Lactobacillus casei (32 isolates, Lactobacillus kefiri (31 isolates, Lactococcus lactis (24 isolates, Acetobacter lovaniensis (32 isolates, Kluyveromyces lactis (31 isolates, Kazachstania aerobia (23 isolates, Saccharomyces cerevisiae (41 isolates and Lachancea meyersii (15 isolates were the microbial species isolated. Scanning electron microscopy showed that the microbiota was dominated by bacilli (short and curved long cells growing in close association with lemon-shaped yeasts cells. During the 24 h of fermentation, the protein content increased, while lactose and fat content decreased. The concentration of lactic acid ranged from 1.4 to 17.4 mg/ml, and that of acetic acid increased from 2.1 to 2.73 mg/ml. The production of ethanol was limited, reaching a final mean value of 0.5 mg/ml.

Brazilian kefir: structure, microbial communities and chemical composition

Science.gov (United States)

Magalhães, Karina Teixeira; de Melo Pereira, Gilberto Vinícius; Campos, Cássia Roberta; Dragone, Giuliano; Schwan, Rosane Freitas

2011-01-01

Microbial ecology and chemical composition of Brazilian kefir beverage was performed. The microorganisms associated with Brazilian kefir were investigated using a combination of phenotypic and genotypic methods. A total of 359 microbial isolates were identified. Lactic acid bacteria (60.5%) were the major isolated group identified, followed by yeasts (30.6%) and acetic acid bacteria (8.9%). Lactobacillus paracasei (89 isolates), Lactobacillus parabuchneri (41 isolates), Lactobacillus casei (32 isolates), Lactobacillus kefiri (31 isolates), Lactococcus lactis (24 isolates), Acetobacter lovaniensis (32 isolates), Kluyveromyces lactis (31 isolates), Kazachstania aerobia (23 isolates), Saccharomyces cerevisiae (41 isolates) and Lachancea meyersii (15 isolates) were the microbial species isolated. Scanning electron microscopy showed that the microbiota was dominated by bacilli (short and curved long) cells growing in close association with lemon-shaped yeasts cells. During the 24 h of fermentation, the protein content increased, while lactose and fat content decreased. The concentration of lactic acid ranged from 1.4 to 17.4 mg/ml, and that of acetic acid increased from 2.1 to 2.73 mg/ml. The production of ethanol was limited, reaching a final mean value of 0.5 mg/ml. PMID:24031681

Apple Polysaccharide inhibits microbial dysbiosis and chronic inflammation and modulates gut permeability in HFD-fed rats.

Science.gov (United States)

Wang, Sheng; Li, Qian; Zang, Yue; Zhao, Yang; Liu, Nan; Wang, Yifei; Xu, Xiaotao; Liu, Li; Mei, Qibing

2017-06-01

The saying "An apple a day keeps the doctor away" has been known for over 150 years, and numerous studies have shown that apple consumption is closely associated with reduced risks of chronic diseases. It has been well accepted that dysbiosis is the reflection of various chronic diseases. Therefore, this study investigates the effects of apple polysaccharides (AP) on gut dysbiosis. High-fat diet (HFD) fed rats were treated for 14 weeks with AP. The microbiota composition, microbiota-generated short chain fatty acids (SCFAs), gut permeability and chronic inflammation were analyzed. AP treatment showed higher abundance of Bacteroidetes and Lactobacillus while lower Firmicutes and Fusobacteium. AP significantly increased total SCFAs level that contributed by acetic acid and isobutyric acid. Moreover, AP dramatically alleviated dysbiosis-associated gut permeability and chronic inflammation with decreased plasma LBP, up-regulation of Occludin, down-regulation of tumor necrosis factor a (TNF-a), monocyte chemotactic protein 1 (MCP-1), chemokine ligand 1 (CXCL-1) and interleukin 1 beta (IL-1β). The potential mechanism is due to the fact that AP reduces gut permeability, which involves the induction of autophagy in goblet cells. Therefore, AP exerts health benefits through inhibiting gut dysbiosis and chronic inflammation and modulating gut permeability in HFD-induced dysbiosis rats. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of influent strength on microorganisms in surface flow mesocosm wetlands.

Science.gov (United States)

Tao, Wendong; Hall, Ken J; Ramey, William

2007-11-01

To choose an appropriate dilution ratio to treat woodwaste leachate without inhibition on heterotrophic bacteria, microbial ATP concentration and the rates of heterotrophic leucine incorporation and acetate uptake were compared across surface flow mesocosm wetlands fed with different strengths of influent. Abundances of protozoa and respiring bacteria were investigated in two mesocosm wetlands to elucidate the effects of influent strength on heterotrophic bacteria. The strongest influent or the raw leachate did not show a significant inhibitory effect on leucine incorporation and acetate uptake. Instead, leucine incorporation rates by bacteria in water, epiphytic biofilm and sediment were higher in mesocosm wetlands fed with a stronger influent. There were significantly more respiring planktonic bacteria (451 x 10(5) mL(-1)) and fewer nanoflagellates (3.8 x 10(3) mL(-1)) in the mesocosm fed with a strong influent, while fewer respiring planktonic bacteria (38.7 x 10(5)mL(-1)) and more nanoflagellates (15.4 x 10(3) mL(-1)) in the mesocosm fed with a weak influent. The majority of the total microbial ATP was attributed to sedimentary bacteria, of which >96% were inactive. Heterotrophic activity and its distribution among water, epiphytic biofilm and sediment in the mesocosm wetlands were affected by availability of bacterial substrates and grazing pressure of nanoflagellates.

Isolation of acetic, propionic and butyric acid-forming bacteria from biogas plants.

Science.gov (United States)

Cibis, Katharina Gabriela; Gneipel, Armin; König, Helmut

2016-02-20

In this study, acetic, propionic and butyric acid-forming bacteria were isolated from thermophilic and mesophilic biogas plants (BGP) located in Germany. The fermenters were fed with maize silage and cattle or swine manure. Furthermore, pressurized laboratory fermenters digesting maize silage were sampled. Enrichment cultures for the isolation of acid-forming bacteria were grown in minimal medium supplemented with one of the following carbon sources: Na(+)-dl-lactate, succinate, ethanol, glycerol, glucose or a mixture of amino acids. These substrates could be converted by the isolates to acetic, propionic or butyric acid. In total, 49 isolates were obtained, which belonged to the phyla Firmicutes, Tenericutes or Thermotogae. According to 16S rRNA gene sequences, most isolates were related to Clostridium sporosphaeroides, Defluviitoga tunisiensis and Dendrosporobacter quercicolus. Acetic, propionic or butyric acid were produced in cultures of isolates affiliated to Bacillus thermoamylovorans, Clostridium aminovalericum, Clostridium cochlearium/Clostridium tetani, C. sporosphaeroides, D. quercicolus, Proteiniborus ethanoligenes, Selenomonas bovis and Tepidanaerobacter sp. Isolates related to Thermoanaerobacterium thermosaccharolyticum produced acetic, butyric and lactic acid, and isolates related to D. tunisiensis formed acetic acid. Specific primer sets targeting 16S rRNA gene sequences were designed and used for real-time quantitative PCR (qPCR). The isolates were physiologically characterized and their role in BGP discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

Microbial Succession and Flavor Production in the Fermented Dairy Beverage Kefir.

Science.gov (United States)

Walsh, Aaron M; Crispie, Fiona; Kilcawley, Kieran; O'Sullivan, Orla; O'Sullivan, Maurice G; Claesson, Marcus J; Cotter, Paul D

2016-01-01

Kefir is a putatively health-promoting dairy beverage that is produced when a kefir grain, consisting of a consortium of microorganisms, is added to milk to initiate a natural fermentation. Here, a detailed analysis was carried out to determine how the microbial population, gene content, and flavor of three kefirs from distinct geographic locations change over the course of 24-h fermentations. Metagenomic sequencing revealed that Lactobacillus kefiranofaciens was the dominant bacterial species in kefir during early stages of fermentations but that Leuconostoc mesenteroides became more prevalent in later stages. This pattern is consistent with an observation that genes involved in aromatic amino acid biosynthesis were absent from L. kefiranofaciens but were present in L. mesenteroides . Additionally, these shifts in the microbial community structure, and associated pathways, corresponded to changes in the levels of volatile compounds. Specifically, Acetobacter spp. correlated with acetic acid; Lactobacillus spp. correlated with carboxylic acids, esters and ketones; Leuconostoc spp. correlated with acetic acid and 2,3-butanedione; and Saccharomyces spp. correlated with esters. The correlation data suggest a causal relationship between microbial taxa and flavor that is supported by observations that addition of L. kefiranofaciens NCFB 2797 increased the levels of esters and ketones whereas addition of L. mesenteroides 213M0 increased the levels of acetic acid and 2,3-butanedione. Finally, we detected genes associated with probiotic functionalities in the kefir microbiome. Our results illustrate the dynamic nature of kefir fermentations and microbial succession patterns therein and can be applied to optimize the fermentation processes, flavors, and health-related attributes of this and other fermented foods. IMPORTANCE Traditional fermented foods represent relatively low-complexity microbial environments that can be used as model microbial communities to understand

Draft Genome Sequence of an Active Heterotrophic Nitrifier-Denitrifier, Cupriavidus pauculus UM1.

Science.gov (United States)

Putonti, Catherine; Polley, Nathaniel; Castignetti, Domenic

2018-02-08

Here, we present the draft genome sequence of Cupriavidus pauculus UM1, a metal-resistant heterotrophic nitrifier-denitrifier capable of synthesizing nitrite from pyruvic oxime. The size of the genome is 7,402,815 bp with a GC content of 64.8%. This draft assembly consists of 38 scaffolds. Copyright © 2018 Putonti et al.

Determination of charge transfer resistance and capacitance of microbial fuel cell through a transient response analysis of cell voltage.

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Ha, Phuc Thi; Moon, Hyunsoo; Kim, Byung Hong; Ng, How Yong; Chang, In Seop

2010-03-15

An alternative method for determining the charge transfer resistance and double-layer capacitance of microbial fuel cells (MFCs), easily implemented without a potentiostat, was developed. A dynamic model with two parameters, the charge transfer resistance and double-layer capacitance of electrodes, was derived from a linear differential equation to depict the current generation with respect to activation overvoltage. This model was then used to fit the transient cell voltage response to the current step change during the continuous operation of a flat-plate type MFC fed with acetate. Variations of the charge transfer resistance and the capacitance value with respect to the MFC design conditions (biocatalyst existence and electrode area) and operating parameters (acetate concentration and buffer strength in the catholyte) were then determined to elucidate the validity of the proposed method. This model was able to describe the dynamic behavior of the MFC during current change in the activation loss region; having an R(2) value of over 0.99 in most tests. Variations of the charge transfer resistance value (thousands of Omega) according to the change of the design factors and operational factors were well-correlated with the corresponding MFC performances. However, though the capacitance values (approximately 0.02 F) reflected the expected trend according to the electrode area change and catalyst property, they did not show significant variation with changes in either the acetate concentration or buffer strength. (c) 2009 Elsevier B.V. All rights reserved.

Probiotic and Acetic Acid Effect on Broiler Chickens Performance

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Martin Král

2011-05-01

Full Text Available Probiotics and organic acids are widely accepted as an alternative to in-feed antibiotics in poultry production. We carried the experiment with broiler chickens. In experiment we research effect of probiotic and acetic acids on the performance of broiler chickens. A total number of 200 one day old broiler chickens were distributed to two dietary groups. Broiler chickens in control group were fed with standard feed mixture and experimental group 1% vinegar contained 5% acetic acid used in drinking water and probiotics mixed with feed mixture. Body weight, FCR and GIT pH were recorded. The performance showed no statistically significant increase in body weight (P>0.05 in the weeks 1, 2, 3 and 4 of age. The body weight of broiler chickens was significant increase (P0.05 in weeks 5, and 6 of age. In different segments of the GIT was not statistically significant (P>0.05 difference of pH between the control and experimental groups.

Acetate and phosphate anion adsorption linear sweep voltammograms simulated using density functional theory

KAUST Repository

Savizi, Iman Shahidi Pour

2011-04-01

Specific adsorption of anions to electrode surfaces may alter the rates of electrocatalytic reactions. Density functional theory (DFT) methods are used to predict the adsorption free energy of acetate and phosphate anions as a function of Pt(1 1 1) electrode potential. Four models of the electrode potential are used including a simple vacuum slab model, an applied electric field model with and without the inclusion of a solvating water bi-layer, and the double reference model. The linear sweep voltammogram (LSV) due to anion adsorption is simulated using the DFT results. The inclusion of solvation at the electrochemical interface is necessary for accurately predicting the adsorption peak position. The Langmuir model is sufficient for predicting the adsorption peak shape, indicating coverage effects are minor in altering the LSV for acetate and phosphate adsorption. Anion adsorption peak positions are determined for solution phase anion concentrations present in microbial fuel cells and microbial electrolysis cells and discussion is provided as to the impact of anion adsorption on oxygen reduction and hydrogen evolution reaction rates in these devices. © 2011 Elsevier Ltd. All rights reserved.

Vapor-fed bio-hybrid fuel cell.

Science.gov (United States)

Benyamin, Marcus S; Jahnke, Justin P; Mackie, David M

2017-01-01

Concentration and purification of ethanol and other biofuels from fermentations are energy-intensive processes, with amplified costs at smaller scales. To circumvent the need for these processes, and to potentially reduce transportation costs as well, we have previously investigated bio-hybrid fuel cells (FCs), in which a fermentation and FC are closely coupled. However, long-term operation requires strictly preventing the fermentation and FC from harming each other. We introduce here the concept of the vapor-fed bio-hybrid FC as a means of continuously extracting power from ongoing fermentations at ambient conditions. By bubbling a carrier gas (N 2 ) through a yeast fermentation and then through a direct ethanol FC, we protect the FC anode from the catalyst poisons in the fermentation (which are non-volatile), and also protect the yeast from harmful FC products (notably acetic acid) and from build-up of ethanol. Since vapor-fed direct ethanol FCs at ambient conditions have never been systematically characterized (in contrast to vapor-fed direct methanol FCs), we first assess the effects on output power and conversion efficiency of ethanol concentration, vapor flow rate, and FC voltage. The results fit a continuous stirred-tank reactor model. Over a wide range of ethanol partial pressures (2-8 mmHg), power densities are comparable to those for liquid-fed direct ethanol FCs at the same temperature, with power densities >2 mW/cm 2 obtained. We then demonstrate the continuous operation of a vapor-fed bio-hybrid FC with fermentation for 5 months, with no indication of performance degradation due to poisoning (of either the FC or the fermentation). It is further shown that the system is stable, recovering quickly from disturbances or from interruptions in maintenance. The vapor-fed bio-hybrid FC enables extraction of power from dilute bio-ethanol streams without costly concentration and purification steps. The concept should be scalable to both large and small

New Zealand Coals - A Potential Feedstock for Deep Microbial Life

DEFF Research Database (Denmark)

Glombitza, Clemens

2010-01-01

into the surrounding. Previous studies showed that especially oxygen containing compounds are lost from the macromolecular matrix during diagenesis and early catagenesis. Oxygen containing low molecular weight organic acids (LMWOAs) such as formate, acetate and oxalate represent important substrates for microbial...... reactions. Formate, acetate and oxalate were found to decrease continously from early diagenesis to early catagenesis. This suggests a constant release of these compounds during this maturation interval providing a suitable feedstock for microbial ecosystems in geological time spans. Investigation...... of kerogen-bound high molecular weight fatty acids show for the long chain fatty acids (C20-C30), representing a terrestrial plant material signal, a constant decrease during diagenesis and early catagenesis. In contrast the short chain fatty acids (mainly C16 and C18) show an increase again during early...

Distal, not proximal, colonic acetate infusions promote fat oxidation and improve metabolic markers in overweight/obese men

DEFF Research Database (Denmark)

van der Beek, Christina M; Canfora, Emanuel E; Lenaerts, Kaatje

2016-01-01

, circulating hormones or inflammatory markers. In conclusion distal colonic acetate infusions affected whole-body substrate metabolism, with a pronounced increase in fasting fat oxidation and plasma PYY. Modulating colonic acetate may be a nutritional target to treat or prevent metabolic disorders.......Gut microbial-derived short-chain fatty acids (SCFA) are believed to affect host metabolism and cardiometabolic risk factors. The present study aim was to investigate the effects of proximal and distal colonic infusions with the SCFA acetate on fat oxidation and other metabolic parameters in men...... in the colon for three consecutive test days, enabling colonic acetate (100 or 180 mmol/l) or placebo infusion during fasting conditions and after an oral glucose load (postprandial). Fat oxidation and energy expenditure were measured using an open-circuit ventilated hood system and blood samples were...

Heat-treatment, phytase and fermented liquid feeding affect the presence of inositol phosphates in ileal digesta and phosphorus digestibility in pigs fed a wheat and barley diet

DEFF Research Database (Denmark)

Blaabjerg, Karoline; Jørgensen, H.; Tauson, Anne-Helene

2010-01-01

The aim was to evaluate the effect of heat-treatment, microbial phytase addition and feeding strategy (dry feeding v. fermented liquid feeding) on degradation of phytate (myo-inositol hexakisphosphate, InsP6) and formation and further degradation of lower inositol phosphates (myo-inositol pentaki......The aim was to evaluate the effect of heat-treatment, microbial phytase addition and feeding strategy (dry feeding v. fermented liquid feeding) on degradation of phytate (myo-inositol hexakisphosphate, InsP6) and formation and further degradation of lower inositol phosphates (myo...... × 4 Latin square with four pigs fed four diets. A basal wheat/barley-based diet was fed either as non-heat-treated or heat-treated (steam-pelleted at 90°C). The heat-treatment resulted in an inactivation of plant phytase below detectable level. Diet 1 (non-heat-treated basal diet fed dry); diet 2...... (heat-treated basal diet fed dry); diet 3 (as diet 2 but with microbial phytase (750 FTU/kg as fed) fed dry); diet 4 (as diet 3 fed liquid (fermented for 17.5 h nighttime and 6.5 h daytime at 20°C with 50% residue in the tank)). Chromic oxide (Cr2O3) was included as marker and ATTD was determined both...

Acetate Kinase Isozymes Confer Robustness in Acetate Metabolism

DEFF Research Database (Denmark)

Chan, Siu Hung Joshua; Nørregaard, Lasse; Solem, Christian

2014-01-01

transcription structure, determining enzyme characteristics and effect on growth physiology. The results show that the two ACKs are most likely individually transcribed. AckA1 has a much higher turnover number and AckA2 has a much higher affinity for acetate in vitro. Consistently, growth experiments of mutant...... physiological roles in L. lactis to maintain a robust acetate metabolism for fast growth at different extracellular acetate concentrations. The existence of ACK isozymes may reflect a common evolutionary strategy in bacteria in an environment with varying concentrations of acetate.......Acetate kinase (ACK) (EC no: 2.7.2.1) interconverts acetyl-phosphate and acetate to either catabolize or synthesize acetyl-CoA dependent on the metabolic requirement. Among all ACK entries available in UniProt, we found that around 45% are multiple ACKs in some organisms including more than 300...

Effect of a direct-fed microbial (Primalac) on structure and ultrastructure of small intestine in turkey poults.

Science.gov (United States)

Rahimi, S; Grimes, J L; Fletcher, O; Oviedo, E; Sheldon, B W

2009-03-01

The effects of dietary supplementation of the direct-fed microbial (DFM) Primalac in mash or crumbled feed on histological and ultrastructural changes of intestinal mucosa was determined in 2 populations of poults; 1 with and 1 without a Salmonella spp. challenge. Three hundred thirty-six 1-d-old female Large White turkey poults were randomly distributed into 8 treatment groups with 6 replicates of 7 poults in each pen. The poults were placed on 1 of 4 dietary treatments in a 2 x 2 x 2 factorial arrangement (mash or crumble feed, with or without DFM, not-challenged or challenged at 3 d of age). The DFM groups were fed a Primalac-supplemented diet from d 1 until the last day of the experiment (d 21). At 3 d of age, 50% of the poults were challenged with 1 mL of 10(10) cfu/ mL of Salmonella spp. (Salmonella enterica serovar Typhimurium, Salmonella Heidelberg, and Salmonella Kentucky) by oral gavage. The inoculated poults were housed in a separate room from nonchallenged controls. Feed and water were provided ad libitum for all birds. At d 21, 1 poult per pen (total of 6 poults per treatment) was randomly selected and killed humanely by cervical dislocation. After necropsy, the small intestine was removed, and tissue samples from duodenum, jejunum, and ileum were taken for light and electron microscopic evaluation. The DFM birds showed increased goblet cell (GC) numbers, total GC area, GC mean size, mucosal thickness, and a greater number of segmented filamentous bacteria compared with controls. Changes in intestinal morphology as observed in this study support the concept that poultry gut health and function, and ultimately bird performance, can be improved by dietary supplementation with DFM products such as Primalac as used in this study.

Molecular approaches to understand the regulation of N2O emission from denitrifying bacteria - model strains and soil communities (Invited)

Science.gov (United States)

Frostegard, A.; Bakken, L. R.

2010-12-01

Emissions of N2O from agricultural soils are largely caused by denitrifying bacteria. Field measurements of N2O fluxes show large variations and depend on several environmental factors, and possibly also on the composition of the denitrifying microbial community. The temporal and spatial variation of fluxes are not adequately captured by biogeochemical models, and few options for mitigations have been invented, which underscores the need to understand the mechanisms underlying the emissions of N2O. Analyses of denitrification genes and transcripts extracted from soils are important for describing the system, but may have limited value for prediction of N2O emissions. In contrast, phenotypic analyses are direct measures of the organisms’ responses to changing environmental conditions. Our approach is to combine phenotypic characterizations using high-resolution gas kinetics, with gene transcription analyses to study denitrification regulatory phenotypes (DRP) of bacterial strains or complex microbial communities. The rich data sets obtained provide a basis for refinement of biochemical and physiological research on this key process in the nitrogen cycle. The strength of this combined approach is illustrated by a series of experiments investigating effects of soil pH on denitrification. Soil pH emerges as a master variable determining the microbial community composition as well as its denitrification product ratio (N2O/N2), with higher ratio in acid than in alkaline soil. It is therefore likely that emissions of N2O from agro-ecosystems will increase in large parts of the world where soil pH is decreasing due to intensified management and increased use of chemical fertilizers. Considering its immense implications, surprisingly few attempts have been made to unravel the mechanisms involved in the pH-control of the product stoichiometry of denitrification. We investigated the kinetics of gas transformations (O2, NO, N2O and N2) and transcription of functional genes

Supportive treatment with megestrol acetate during radio-(chemo-)therapy. A randomized trial

International Nuclear Information System (INIS)

Fietkau, R.; Sauer, R.

1996-01-01

Background: The value of megestrol acetate in treating tumor anorexia and cachexia of terminal patients is well known. However, the supportive effect of megestrol acetate during intensive radio-(chemo-)therapy was not investigated up to now. Therefore a randomized trial was performed including patients with advanced tumors in the head and neck region. Patients and Methods: From June 1991 to December 1993 a total of 64 patients were admitted to a randomized, double-blind placebo-controlled study. During and up to 6 weeks following radiotherapy patients received 160 mg/d megestrol acetate or placebo. The nutritional status (anthropometric and laboratory parameters) and the quality-of-life index according to Padilla et al. were determined prior to therapy, 1, 4, 6 weeks later during radiotherapy and 12, 18 weeks after completion. Results: Sixty-one out of 64 patients were evaluable (control group: n=30; megestrol acetate patients: n=31). One patients refused further participation after randomization. One patient in each arm was excluded due to side effects (impotence, diarrhoea). Further side effects were not observed. In the control group the nutrititional parameters (body weight, triceps skinfold) and the subjective feeling of the patients deteriorated during radiotherapy and did not restore following radiotherapy. By contrast, the patients of the megestrol acetate group were able to stabilize these parameters. This difference was most prominent in the orally nourished patients (weight loss during therapy: Control group: -4.1 kg; megestrol acetate group: -0.8 kg; p=0.004); but not in the patients fed by percutaneous endoscopically guided gastrostomy (weight loss control group: -2.4 kg; megestrol acetate group: -0.8 kg; p=0.14). Conclusion: In patients on radiochemotherapy megestrol acetate prevents patients from further deterioration of the nutritional status and quality of life. (orig.) [de

Calcination of calcium acetate and calcium magnesium acetate: effect of the reacting atmosphere

Energy Technology Data Exchange (ETDEWEB)

Adanez, J.; Diego, L.F. de; Garcia-Labiano, F. [Instituto de Carboquimica, Zaragoza (Spain). Dept. of Energy and Environment

1999-04-01

The calcination process of the calcium acetate (CA) and calcium magnesium acetate (CMA) was investigated as a previous step for coal gas desulfurisation during sorbent injection at high temperatures because the excellent results demonstrated by these sorbents as sulfur removal agents both in combustion and gasification processes. As pore structure developed during calcination is one of the most important characteristics of the sorbent related with the later reaction with the gaseous pollutants, several calcination tests were conducted in a drop tube reactor at temperatures from 700{degree}C to 1100{degree}C, and residence times from 0.8 to 2.4 s. Four different gas atmospheres were used for comparative purposes: inert, oxidising, reducing, and non-calcining (pure CO{sub 2}). Despite the advantage of the high porous cenospheric structure developed by these sorbents during their injection at high temperature, calcination of the CaCO{sub 3} was not complete even at the longest residence time, 2.4 s, and the highest temperature, 1100{degree}C, tested. An important effect of the reacting atmosphere on the calcination conversion and on the sorbent pore structure was detected. The CO{sub 2} concentration around the particle, both that fed in the reacting gases or that generated by organic material combustion, seems to be responsible for the final calcination conversions obtained in each case, also affecting the sintering suffered by the sorbents. 19 refs., 10 figs.

Comparative Metagenomic Analysis of Electrogenic Microbial Communities in Differentially Inoculated Swine Wastewater-Fed Microbial Fuel Cells

Directory of Open Access Journals (Sweden)

Irina V. Khilyas

2017-01-01

Full Text Available Bioelectrochemical systems such as microbial fuel cells (MFCs are promising new technologies for efficient removal of organic compounds from industrial wastewaters, including that generated from swine farming. We inoculated two pairs of laboratory-scale MFCs with sludge granules from a beer wastewater-treating anaerobic digester (IGBS or from sludge taken from the bottom of a tank receiving swine wastewater (SS. The SS-inoculated MFC outperformed the IGBS-inoculated MFC with regard to COD and VFA removal and electricity production. Using a metagenomic approach, we describe the microbial diversity of the MFC planktonic and anodic communities derived from the different inocula. Proteobacteria (mostly Deltaproteobacteria became the predominant phylum in both MFC anodic communities with amplification of the electrogenic genus Geobacter being the most pronounced. Eight dominant and three minor species of Geobacter were found in both MFC anodic communities. The anodic communities of the SS-inoculated MFCs had a higher proportion of Clostridium and Bacteroides relative to those of the IGBS-inoculated MFCs, which were enriched with Pelobacter. The archaeal populations of the SS- and IGBS-inoculated MFCs were dominated by Methanosarcina barkeri and Methanothermobacter thermautotrophicus, respectively. Our results show a long-term influence of inoculum type on the performance and microbial community composition of swine wastewater-treating MFCs.

Effects of pre-fermentation and pulsed-electric-field treatment of primary sludge in microbial electrochemical cells.

Science.gov (United States)

Ki, Dongwon; Parameswaran, Prathap; Popat, Sudeep C; Rittmann, Bruce E; Torres, César I

2015-11-01

The aim of this study was to investigate the combination of two technologies - pulsed electric field (PEF) pre-treatment and semi-continuous pre-fermentation of primary sludge (PS) - to produce volatile fatty acids (VFAs) as the electron donor for microbial electrolysis cells (MECs). Pre-fermentation with a 3-day solids retention time (SRT) led to the maximum generation of VFAs, with or without pretreatment of the PS through pulsed-electric-fields (PEF). PEF treatment before fermentation enhanced the accumulation of the preferred VFA, acetate, by 2.6-fold. Correspondingly, MEC anodes fed with centrate from 3-day pre-fermentation of PEF-treated PS had a maximum current density ∼3.1 A/m(2), which was 2.4-fold greater than the control pre-fermented centrate. Over the full duration of batch MEC experiments, using pre-fermented centrate led to successful performance in terms of Coulombic efficiency (95%), Coulombic recovery (80%), and COD-removal efficiency (85%). Copyright © 2015 Elsevier Ltd. All rights reserved.

Growth performance, duodenal morphology and the caecal microbial population in female broiler chickens fed glycine-fortified low protein diets under heat stress conditions.

Science.gov (United States)

Awad, E A; Idrus, Z; Soleimani Farjam, A; Bello, A U; Jahromi, M F

2018-03-09

1. This study was undertaken to examine the effect of feeding glycine (Gly)-fortified low protein (LP) diets on the growth performance, duodenal morphology and caecal microbial populations of broiler chickens raised under unheated, cyclic or constant heat stress environmental conditions. 2. From d 1 to 21 (starter phase), an equivalent number of birds were fed either a normal protein (NP) diet or a LP diet fortified with Gly. From d 22 to 42 (grower phase), an equivalent number of birds from each starter diet were distributed to one of the following dietary groups: (i) an NP diet during the starter and grower phases (NPNP), (ii) an NP diet during the starter phase and a LP diet during the grower phase (NPLP), (iii) an LP diet during the starter phase and an NP diet during the grower phase (LPNP) or (iv) LP diets during both phases (LPLP). 3. Commencing from d 22, an equivalent number of birds from each dietary group were exposed to (i) 23 ± 1°C throughout (unheated), (ii) 34 ± 1°C for 7 h each day from 10:00 to 17:00 (cyclic heat) or (iii) 34 ± 1°C throughout (constant heat). 4. Feeding the LP diet during the starter phase resulted in feed intake (FI), weight gain (WG), feed conversion ratios (FCR) and energy efficiency ratios (EER) similar to those for the NP diet. The birds fed the LP diet had a significantly higher protein efficiency ratio (PER) compared with the birds fed the NP diet. 5. During the grower phase, there were significant diet × temperature interactions for F, WG, FCR, PER, EER, villus height, crypt depth and caecal Clostridia. The birds fed the NPLP and LPLP diets had lower FI, WG and EER, higher FCR, shorter villus height and crypt depth and higher caecal Clostridia compared with the birds fed LPNP and NPNP diets under constant heat stress. However, feeding birds the NPLP and LPLP diets resulted in FI, WG, EER, FCR, morphology parameters and caecal Clostridia equivalent to the birds fed LPNP and NPNP diets, as well as improved PER

Disentangling the rhizosphere effect on nitrate reducers and denitrifiers: insight into the role of root exudates.

Science.gov (United States)

Henry, S; Texier, S; Hallet, S; Bru, D; Dambreville, C; Chèneby, D; Bizouard, F; Germon, J C; Philippot, L

2008-11-01

To determine to which extent root-derived carbon contributes to the effects of plants on nitrate reducers and denitrifiers, four solutions containing different proportions of sugar, organic acids and amino acids mimicking maize root exudates were added daily to soil microcosms at a concentration of 150 microg C g(-1) of soil. Water-amended soils were used as controls. After 1 month, the size and structure of the nitrate reducer and denitrifier communities were analysed using the narG and napA, and the nirK, nirS and nosZ genes as molecular markers respectively. Addition of artificial root exudates (ARE) did not strongly affect the structure or the density of nitrate reducer and denitrifier communities whereas potential nitrate reductase and denitrification activities were stimulated by the addition of root exudates. An effect of ARE composition was also observed on N(2)O production with an N(2)O:(N(2)O + N(2)) ratio of 0.3 in microcosms amended with ARE containing 80% of sugar and of 1 in microcosms amended with ARE containing 40% of sugar. Our study indicated that ARE stimulated nitrate reduction or denitrification activity with increases in the range of those observed with the whole plant. Furthermore, we demonstrated that the composition of the ARE affected the nature of the end-product of denitrification and could thus have a putative impact on greenhouse gas emissions.

Microbial phytase and liquid feeding increase phytate degradation in the gastrointestinal tract of growing pigs

DEFF Research Database (Denmark)

Blaabjerg, Karoline; Poulsen, Hanne Damgaard

2010-01-01

The quantitative degradation of inositol phosphates (InsP6 to InsP2) in the stomach and small intestine as influenced by microbial phytase and fermented liquid feeding was compared by combining the results from two experiments. Six pigs (49 kg) were fitted with gastric cannulas ( Exp. 1 ) and 3...... with microbial phytase (750 FTU/kg) fed dry; diet 3, diet 2 fed in liquid form (fermented 17.5 h, 20 °C, 50% residual in the tank). InsP6-P was not present in gastric or ileal digesta in pigs fed diet 3 due to complete InsP6 degradation before feeding. In pigs fed diet 2 the amount of gastric InsP6-P...... was considerably smaller compared with pigs fed diet 1 due to phytase addition (P ≤ 0.001). On the other hand, the amount of ileal InsP6-P was only slightly less in pigs fed diet 2 compared with diet 1 indicating that InsP6 is greatly degraded in the small intestine. Furthermore, the amounts of gastric or ileal...

Microbially influenced corrosion communities associated with fuel-grade ethanol environments.

Science.gov (United States)

Williamson, Charles H D; Jain, Luke A; Mishra, Brajendra; Olson, David L; Spear, John R

2015-08-01

Microbially influenced corrosion (MIC) is a costly problem that impacts hydrocarbon production and processing equipment, water distribution systems, ships, railcars, and other types of metallic infrastructure. In particular, MIC is known to cause considerable damage to hydrocarbon fuel infrastructure including production, transportation, and storage systems, often times with catastrophic environmental contamination results. As the production and use of alternative fuels such as fuel-grade ethanol (FGE) increase, it is important to consider MIC of engineered materials exposed to these "newer fuels" as they enter existing infrastructure. Reports of suspected MIC in systems handling FGE and water prompted an investigation of the microbial diversity associated with these environments. Small subunit ribosomal RNA gene pyrosequencing surveys indicate that acetic-acid-producing bacteria (Acetobacter spp. and Gluconacetobacter spp.) are prevalent in environments exposed to FGE and water. Other microbes previously implicated in corrosion, such as sulfate-reducing bacteria and methanogens, were also identified. In addition, acetic-acid-producing microbes and sulfate-reducing microbes were cultivated from sampled environments containing FGE and water. Results indicate that complex microbial communities form in these FGE environments and could cause significant MIC-related damage that may be difficult to control. How to better manage these microbial communities will be a defining aspect of improving mitigation of global infrastructure corrosion.

Dietary marker effects on fecal microbial ecology, fecal VFA, nutrient digestibility coefficients, and growth performance in finishing pigs.

Science.gov (United States)

Kerr, B J; Weber, T E; Ziemer, C J

2015-05-01

Use of indigestible markers such as Cr2O3, Fe2O3, and TiO2 are commonly used in animal studies to evaluate digesta rate of passage and nutrient digestibility. Yet, the potential impact of indigestible markers on fecal microbial ecology and subsequent VFA generation is not known. Two experiments utilizing a total of 72 individually fed finishing pigs were conducted to describe the impact of dietary markers on fecal microbial ecology, fecal ammonia and VFA concentrations, nutrient digestibility, and pig performance. All pigs were fed a common diet with no marker or with 0.5% Cr2O3, Fe2O3, or TiO2. In Exp. 1, after 33 d of feeding, fresh fecal samples were collected for evaluation of microbial ecology, fecal ammonia and VFA concentrations, and nutrient digestibility, along with measures of animal performance. No differences were noted in total microbes or bacterial counts in pig feces obtained from pigs fed the different dietary markers while Archaea counts were decreased (P = 0.07) in feces obtained from pigs fed the diet containing Fe2O 3compared to pigs fed the control diet. Feeding Cr2O3, Fe2O3, or TiO2 increased fecal bacterial richness (P = 0.03, 0.01, and 0.10; respectively) when compared to pigs fed diets containing no marker, but no dietary marker effects were noted on fecal microbial evenness or the Shannon-Wiener index. Analysis of denaturing gradient gel electrophoresis gels did not reveal band pattern alterations due to inclusion of dietary markers in pig diets. There was no effect of dietary marker on fecal DM, ammonia, or VFA concentrations. Pigs fed diets containing Cr2O3 had greater Ca, Cu, Fe, and P (P ≤ 0.02), but lower Ti ( P= 0.08) digestibility compared to pigs fed the control diet. Pigs fed diets containing Fe2O3 had greater Ca (P = 0.08) but lower Ti (P = 0.01) digestibility compared to pigs fed the control diet. Pigs fed diets containing TiO2 had greater Fe and Zn (P ≤ 0.09), but lower Ti ( P= 0.01) digestibility compared to pigs fed the

Microbial Activity Influences Electrical Conductivity of Biofilm Anode

Science.gov (United States)

This study assessed the conductivity of a Geobacter-enriched biofilm anode along with biofilm activity in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH ...

Microbially-reduced graphene scaffolds to facilitate extracellular electron transfer in microbial fuel cells.

Science.gov (United States)

Yuan, Yong; Zhou, Shungui; Zhao, Bo; Zhuang, Li; Wang, Yueqiang

2012-07-01

A one-pot method is exploited by adding graphene oxide (GO) and acetate into an microbial fuel cell (MFC) in which GO is microbially reduced, leading to in situ construction of a bacteria/graphene network in the anode. The obtained microbially reduced graphene (MRG) exhibits comparable conductivity and physical characteristics to the chemically reduced graphene. Electrochemical measurements reveal that the number of exoelectrogens involved in extracellular electron transfer (EET) to the solid electrode, increases due to the presence of graphene scaffolds, and the EET is facilitated in terms of electron transfer kinetics. As a result, the maximum power density of the MFC is enhanced by 32% (from 1440 to 1905 mW m(-2)) and the coulombic efficiency is improved by 80% (from 30 to 54%). The results demonstrate that the construction of the bacteria/graphene network is an effective alternative to improve the MFC performance. Copyright © 2012 Elsevier Ltd. All rights reserved.

Long-term cathode performance and the microbial communities that develop in microbial fuel cells fed different fermentation endproducts

KAUST Repository

Kiely, Patrick D.; Rader, Geoffrey; Regan, John M.; Logan, Bruce E.

2011-01-01

fermentation (acetic acid, formic acid, lactic acid, succinic acid, or ethanol). Large variations in reactor performance were primarily due to the specific substrates, with power densities ranging from 835±21 to 62±1mW/m3. Cathodes performance degraded over

Hydraulic retention time affects stable acetate production from tofu processing wastewater in extreme-thermophilic (70°C) mixed culture fermentation.

Science.gov (United States)

Chen, Yun; Zhang, Fang; Wang, Ting; Shen, Nan; Yu, Zhong-Wei; Zeng, Raymond J

2016-09-01

Acetate is an important industrial chemical and its production from wastes via mixed culture fermentation (MCF) is economic. In this work, the effect of hydraulic retention time (HRT) on acetate production from tofu processing wastewater (TPW) in extreme-thermophilic (70°C) MCF was first investigated. It was found that long HRT (>3days) could lead to less acetate production while stable acetate production was achieved at short HRT (3days) with the yield of 0.57g-COD/g-CODTPW. The microbial community analysis showed that hydrogenotrophic methanogens (mainly Methanothermobacter) occupied up to 90% of archaea at both HRTs of 3 and 5days. However, Coprothermobacter, the main acetate-degraders, decreased from 35.74% to 10.58% of bacteria when HRT decreased from 5 to 3days, supporting the aggravation of syntrophic acetate oxidation in long HRT. This work demonstrated that HRT was a crucial factor to maintain stable acetate production from TPW in extreme-thermophilic MCF. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Influences of long-term application of organic and inorganic fertilizers on the composition and abundance of nirS-type denitrifiers in black soil].

Science.gov (United States)

Yin, Chang; Fan, Fen-Liang; Li, Zhao-Jun; Song, A-Lin; Zhu, Ping; Peng, Chang; Liang, Yong-Chao

2012-11-01

The objectives of this study were to explore the effects of long-term organic and inorganic fertilizations on the composition and abundance of nirS-type denitrifiers in black soil. Soil samples were collected from 4 treatments (i. e. no fertilizer treatment, CK; organic manure treatment, OM; chemical fertilizer treatment (NPK) and combination of organic and chemical fertilizers treatment (MNPK)) in Gongzhuling Long-term Fertilization Experiment Station. Composition and abundance of nirS-type denitrifiers were analyzed with terminal restriction fragment length polymorphism (T-RFLP) and real-time quantitative PCR (Q-PCR), respectively. Denitrification enzyme activity (DEA) and soil properties were also measured. Application of organic fertilizers (OM and MNPK) significantly increased the DEAs of black soil, with the DEAs in OM and MNPK being 5.92 and 6.03 times higher than that in CK treatment, respectively, whereas there was no significant difference between NPK and CK. OM and MNPK treatments increased the abundances of nirS-type denitrifiers by 2.73 and 3.83 times relative to that of CK treatment, respectively. The abundance of nirS-type denitrifiers in NPK treatment was not significantly different from that of CK. The T-RFLP analysis of nirS genes showed significant differences in community composition between organic and inorganic treatments, with the emergence of a 79 bp T-RF, a significant decrease in relative abundance of the 84 bp T-RF and a loss of the 99 bp T-RF in all organic treatments. Phylogenetic analysis indicated that the airS-type denitrifiers in the black soil were mainly composed of alpha, beta and gamma-Proteobacteria. The 79 bp-type denitrifiers inhabiting exclusively in organic treatments (OM and MNPK) were affiliated to Pseudomonadaceae in gamma-Proteobacteria and Burkholderiales in beta-Proteobacteria. The 84 bp-types were related to Burkholderiales and Rhodocyclales. Correlation analysis indicated that pH, concentrations of total nitrogen

The microbial community of a biofilm contact reactor for the treatment of winery wastewater.

Science.gov (United States)

de Beer, D M; Botes, M; Cloete, T E

2018-02-01

To utilize a three-tiered approach to provide insight into the microbial community structure, the spatial distribution and the metabolic capabilities of organisms of a biofilm in the two towers of a high-rate biological contact reactor treating winery wastewater. Next-generation sequencing indicated that bacteria primarily responsible for the removal of carbohydrates, sugars and alcohol were more abundant in tower 1 than tower 2 while nitrifying and denitrifying bacteria were more abundant in tower 2. Yeast populations differed in each tower. Fluorescent in situ hybridization coupled with confocal microscopy showed distribution of organisms confirming an oxygen gradient across the biofilm depth. The Biolog system (ECO plates) specified the different carbon-metabolizing profiles of the two biofilms. The three-tiered approach confirmed that the addition of a second subunit to the bioreactor, expanded the treatment capacity by augmenting the microbial and metabolic diversity of the system, improving the treatment scope of the system. A three-tiered biofilm analysis provided data required to optimize the design of a bioreactor to provide favourable conditions for the development of a microbial consortium, which has optimal waste removal properties for the treatment requirements at hand. © 2017 The Society for Applied Microbiology.

Recovery of Acetic Acid from An Ethanol Fermentation Broth by Liquid-Liquid Extraction (LLE) Using Various Solvents

International Nuclear Information System (INIS)

Pham, Thi Thu Huong; Kim, Tae Hyun; Um, Byung Hwan

2015-01-01

Liquid-liquid extraction (LLE) using various solvents was studied for recovery of acetic acid from a synthetic ethanol fermentation broth. The microbial fermentation of sugars presented in hydrolyzate gives rise to acetic acid as a byproduct. In order to obtain pure ethanol for use as a biofuel, fermentation broth should be subjected to acetic acid removal step and the recovered acetic acid can be put to industrial use. Herein, batch LLE experiments were carried out at 25°C using a synthetic fermentation broth comprising 20.0 g l -1 acetic acid and 5.0 g l -1 ethanol. Ethyl acetate (EtOAc), tri-n-octylphosphine oxide (TOPO), tri-n-octylamine (TOA), and tri-n-alkylphosphine oxide (TAPO) were utilized as solvents, and the extraction potential of each solvent was evaluated by varying the organic phase-to-aqueous phase ratios as 0.2, 0.5, 1.0, 2.0, and 4.0. The highest acetic acid extraction yield was achieved with TAPO; however, the lowest ethanol-to-acetic acid extraction ratio was obtained using TOPO. In a single-stage batch extraction, 97.0 % and 92.4 % of acetic acid could be extracted using TAPO and TOPO when the ratio of organic-to-aqueous phases is 4:1 respectively. A higher solvent-to-feed ratio resulted in an increase in the ethanol-to-acetic acid ratio, which decreased both acetic acid purity and acetic acid extraction yield.

Substrate potential of last interglacial to Holocene permafrost organic matter for future microbial greenhouse gas production

Science.gov (United States)

Stapel, Janina G.; Schwamborn, Georg; Schirrmeister, Lutz; Horsfield, Brian; Mangelsdorf, Kai

2018-04-01

In this study the organic matter (OM) in several permafrost cores from Bol'shoy Lyakhovsky Island in NE Siberia was investigated. In the context of the observed global warming the aim was to evaluate the potential of freeze-locked OM from different depositional ages to act as a substrate provider for microbial production of greenhouse gases from thawing permafrost. To assess this potential, the concentrations of free and bound acetate, which form an appropriate substrate for methanogenesis, were determined. The largest free-acetate (in pore water) and bound-acetate (organic-matrix-linked) substrate pools were present in interstadial marine isotope stage (MIS) 3 and stadial MIS 4 Yedoma permafrost deposits. In contrast, deposits from the last interglacial MIS 5e (Eemian) contained only a small pool of substrates. The Holocene (MIS 1) deposits revealed a significant bound-acetate pool, representing a future substrate potential upon release during OM degradation. Additionally, pyrolysis experiments on the OM allocated an increased aliphatic character to the MIS 3 and 4 Late Pleistocene deposits, which might indicate less decomposed and presumably more easily degradable OM. Biomarkers for past microbial communities, including those for methanogenic archaea, also showed the highest abundance during MIS 3 and 4, which indicated OM-stimulated microbial degradation and presumably greenhouse gas production during time of deposition. On a broader perspective, Arctic warming will increase and deepen permafrost thaw and favor substrate availability from older freeze-locked permafrost deposits. Thus, the Yedoma deposits especially showed a high potential for providing substrates relevant for microbial greenhouse gas production.

Monitoring the microbial community during solid-state acetic acid fermentation of Zhenjiang aromatic vinegar.

Science.gov (United States)

Xu, Wei; Huang, Zhiyong; Zhang, Xiaojun; Li, Qi; Lu, Zhenming; Shi, Jinsong; Xu, Zhenghong; Ma, Yanhe

2011-09-01

Zhenjiang aromatic vinegar is one of the most famous Chinese traditional vinegars. In this study, change of the microbial community during its fermentation process was investigated. DGGE results showed that microbial community was comparatively stable, and the diversity has a disciplinary series of changes during the fermentation process. It was suggested that domestication of microbes and unique cycle-inoculation style used in the fermentation of Zhenjiang aromatic vinegar were responsible for comparatively stable of the microbial community. Furthermore, two clone libraries were constructed. The results showed that bacteria presented in the fermentation belonged to genus Lactobacillus, Acetobacter, Gluconacetobacter, Staphylococcus, Enterobacter, Pseudomonas, Flavobacterium and Sinorhizobium, while the fungi were genus Saccharomyces. DGGE combined with clone library analysis was an effective and credible technique for analyzing the microbial community during the fermentation process of Zhenjiang aromatic vinegar. Real-time PCR results suggested that the biomass showed a "system microbes self-domestication" process in the first 5 days, then reached a higher level at the 7th day before gradually decreasing until the fermentation ended at the 20th day. This is the first report to study the changes of microbial community during fermentation process of Chinese traditional solid-state fermentation of vinegar. Copyright © 2011 Elsevier Ltd. All rights reserved.

Long-term high-solids anaerobic digestion of food waste: Effects of ammonia on process performance and microbial community.

Science.gov (United States)

Peng, Xuya; Zhang, ShangYi; Li, Lei; Zhao, Xiaofei; Ma, Yao; Shi, Dezhi

2018-04-22

A long-term high solids anaerobic digestion of food waste was conducted to identify microbial mechanisms of ammonia inhibition during digestion and to clarify correlations between ammonia accumulation, microbial community dynamics (diversity, composition, and interactions), and process stability. Results show that the effects of ammonia on process performance and microbial community were indirectly caused by volatile fatty acid accumulation. Excess free ammonia blocked acetate metabolism, leading to process instability. Accumulated acetate caused feedback inhibition at the acetogenesis stage, which resulted in considerable accumulation of propionate, valerate, and other long-chain fatty acids. This high concentration of volatile fatty acids reduced the abundance of syntrophic acetogenic bacteria and allowed hydrolytic fermentative bacteria to dominate. The normally interactive and orderly metabolic network was broken, which further exacerbated the process instability. These results improve the understanding of microbial mechanisms which contribute to process instability and provide guidance for the microbial management of anaerobic digesters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Bioelectricity generation from coconut husk retting wastewater in fed batch operating microbial fuel cell by phenol degrading microorganism

International Nuclear Information System (INIS)

Jayashree, C.; Arulazhagan, P.; Adish Kumar, S.; Kaliappan, S.; Yeom, Ick Tae; Rajesh Banu, J.

2014-01-01

Dual chamber microbial fuel cell (MFC) operated at fed batch mode for the treatment of retting wastewater has potently achieved both current generation and phenol removal. Hydraulic retention time (HRT) of the reactor was varied from 40 days to 10 days. COD (chemical oxygen demand) removal was 91% at 40 days HRT, with an initial COD concentration of 530 ± 50 g m −3 . Retting wastewater with an initial phenol concentration of 320 ± 60 g m −3 procured a highest phenol removal of 93% at 40 days HRT of the microbial fuel cell. Maximum power density of 362 mW m −2 was achieved using retting wastewater at HRT of 20 days with an internal resistance of 150 Ω in a dual chambered MFC. The bacterial strains in anode region, reported to be responsible for potential phenol removal, were identified as Ochrobactrum sp. RA1 (KJ408266), Ochrobactrum sp. RA2 (KJ408267) and Pesudomonas aeruginosa RA3 (KJ408268) using phylogenetic analysis. The study reveals that, dual chambered MFC effectively removed the phenol from retting wastewater along with power generation. - Highlights: • Maximum power density of 362 mW m −2 (150 Ω) was achieved at HRT of 20 days. • 91% COD removal and 93% phenol removal was observed at HRT of 40 days. • 25% coulombic efficiency was achieved in treatment of retting wastewater with MFC. • Phylogenetic analysis detect phenol degrading Ochrobactrum sp.RA1 in anode biofilm. • In addition, Ochrobactrum sp.RA2 and Pseudomonas aeruginosa RA3 were also isolated

MbT-Tool: An open-access tool based on Thermodynamic Electron Equivalents Model to obtain microbial-metabolic reactions to be used in biotechnological process.

Science.gov (United States)

Araujo, Pablo Granda; Gras, Anna; Ginovart, Marta

2016-01-01

Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs) using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics) can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4 (+), NO3 (-), NO2 (-), N2) to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc). MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.

Fecal microbial diversity and putative function in captive western lowland gorillas (Gorilla gorilla gorilla), common chimpanzees (Pan troglodytes), Hamadryas baboons (Papio hamadryas) and binturongs (Arctictis binturong).

Science.gov (United States)

McKenney, Erin A; Ashwell, Melissa; Lambert, Joanna E; Fellner, Vivek

2014-11-01

Microbial populations in the gastrointestinal tract contribute to host health and nutrition. Although gut microbial ecology is well studied in livestock and domestic animals, little is known of the endogenous populations inhabiting primates or carnivora. We characterized microbial populations in fecal cultures from gorillas (Gorilla gorilla gorilla), common chimpanzees (Pan troglodytes), Hamadryas baboons (Papio hamadryas) and binturongs (Arctictis binturong) to compare the microbiomes associated with different gastrointestinal morphologies and different omnivorous feeding strategies. Each species was fed a distinct standardized diet for 2 weeks prior to fecal collection. All diets were formulated to reflect the species' feeding strategies in situ. Fresh fecal samples were pooled within species and used to inoculate in vitro batch cultures. Acetate, propionate, butyrate and valerate were measured after 24 h of incubation. Eubacterial DNA was extracted from individual fecal samples, pooled, and the cpn60 gene region was amplified and then sequenced to identify the major eubacterial constituents associated with each host species. Short chain fatty acids (P < 0.001) and methane (P < 0.001) were significantly different across species. Eubacterial profiles were consistent with fermentation data and suggest an increase in diversity with dietary fiber. © 2014 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Deciphering the microbial ecology in bio- gas reactors for optimizing the anaerobic digestion process

DEFF Research Database (Denmark)

Zhu, Xinyu

of the basic microbial metabolism and ecology, methanogenic microbial communities were enriched in a lab-scale continuous stirred-tank reactor (CSTR) fed with synthetic feedstocks. In the experiment, the substrates used were stepwise simplified (i.e. polysaccharide, monosaccharide, short chain fatty acids...

Microbial and geochemical investigations of dissolved organic carbon and microbial ecology of native waters from the Biscayne and Upper Floridan Aquifers

Science.gov (United States)

Lisle, John T.; Harvey, Ron W.; Aiken, George R.; Metge, David W.

2010-01-01

Groundwater resources in the United States are under ever-increasing demands for potable, irrigation, and recreational uses. Additionally, aquifer systems are being used or targeted for use as storage areas for treated surface waters and (or) groundwaters via injection (for example, aquifer storage and recovery). To date, the influence that the nutrients, including carbon, in the injected water have on native microbial communities and the biogeochemistry in the subsurface zones used for storage of the injectate has not been determined. In this report, we describe a series of experiments that establishes a baseline dataset for the quantity and quality of organic and inorganic carbon and nutrients in the Biscayne Aquifer (BA) and Upper Floridan Aquifer (UFA) in south Florida. The most significant differences between the BA (26 meters below surface) and UFA (366 meters below surface) are the average specific conductance (0.552 and 6.12 microsiemens per centimeter, respectively), dissolved oxygen (1.6 and 0 milligrams per liter, respectively), and oxidation-reduction potential (40.3 and -358 millivolts, respectively). The dissolved organic carbon from the BA is characterized by carbon originating from terrestrial sources and microbial activities, while the UFA has a distinctive microbial signature. Acetate and lactate are the dominant carbon constituents in both aquifers. Additionally, components of the dissolved organic carbon from the UFA have a total trihalomethane-formation potential that is approximately threefold greater than the maximum contaminat level of 80 micrograms per liter established by the U.S. Environmental Protection Agency. The average native bacterial abundances in the aquifers are similar with 4.69x10^4 cells per milliliter in the BA and 1.33x10^4 cells per milliliter in the UFA. The average bacteriophage abundances are also similar with 1.15x10^5 virus-like particles in the BA and 1.92x10^5 virus-like particles in the UFA. Interestingly, ciliated

Long-term exposure to benzalkonium chloride disinfectants results in change of microbial community structure and increased antimicrobial resistance.

Science.gov (United States)

Tandukar, Madan; Oh, Seungdae; Tezel, Ulas; Konstantinidis, Konstantinos T; Pavlostathis, Spyros G

2013-09-03

The effect of benzalkonium chlorides (BACs), a widely used class of quaternary ammonium disinfectants, on microbial community structure and antimicrobial resistance was investigated using three aerobic microbial communities: BACs-unexposed (DP, fed a mixture of dextrin/peptone), BACs-exposed (DPB, fed a mixture of dextrin/peptone and BACs), and BACs-enriched (B, fed only BACs). Long-term exposure to BACs reduced community diversity and resulted in the enrichment of BAC-resistant species, predominantly Pseudomonas species. Exposure of the two microbial communities to BACs significantly decreased their susceptibility to BACs as well as three clinically relevant antibiotics (penicillin G, tetracycline, ciprofloxacin). Increased resistance to BACs and penicillin G of the two BACs-exposed communities is predominantly attributed to degradation or transformation of these compounds, whereas resistance to tetracycline and ciprofloxacin is largely due to the activity of efflux pumps. Quantification of several key multidrug resistance genes showed a much higher number of copies of these genes in the DPB and B microbial communities compared to the DP community. Collectively, our findings indicate that exposure of a microbial community to BACs results in increased antibiotic resistance, which has important implications for both human and environmental health.

In situ hydrogen consumption kinetics as an indicator of subsurface microbial activity

Science.gov (United States)

Harris, S.H.; Smith, R.L.; Suflita, J.M.

2007-01-01

There are few methods available for broadly assessing microbial community metabolism directly within a groundwater environment. In this study, hydrogen consumption rates were estimated from in situ injection/withdrawal tests conducted in two geochemically varying, contaminated aquifers as an approach towards developing such a method. The hydrogen consumption first-order rates varied from 0.002 nM h-1 for an uncontaminated, aerobic site to 2.5 nM h-1 for a contaminated site where sulfate reduction was a predominant process. The method could accommodate the over three orders of magnitude range in rates that existed between subsurface sites. In a denitrifying zone, the hydrogen consumption rate (0.02 nM h-1) was immediately abolished in the presence of air or an antibiotic mixture, suggesting that such measurements may also be sensitive to the effects of environmental perturbations on field microbial activities. Comparable laboratory determinations with sediment slurries exhibited hydrogen consumption kinetics that differed substantially from the field estimates. Because anaerobic degradation of organic matter relies on the rapid consumption of hydrogen and subsequent maintenance at low levels, such in situ measures of hydrogen turnover can serve as a key indicator of the functioning of microbial food webs and may be more reliable than laboratory determinations. ?? 2007 Federation of European Microbiological Societies.

Microbial diversity and their roles in the vinegar fermentation process.

Science.gov (United States)

Li, Sha; Li, Pan; Feng, Feng; Luo, Li-Xin

2015-06-01

Vinegar is one of the oldest acetic acid-diluted solution products in the world. It is produced from any fermentable sugary substrate by various fermentation methods. The final vinegar products possess unique functions, which are endowed with many kinds of compounds formed in the fermentation process. The quality of vinegar is determined by many factors, especially by the raw materials and microbial diversity involved in vinegar fermentation. Given that metabolic products from the fermenting strains are directly related to the quality of the final products of vinegar, the microbial diversity and features of the dominant strains involved in different fermentation stages should be analyzed to improve the strains and stabilize fermentation. Moreover, although numerous microbiological studies have been conducted to examine the process of vinegar fermentation, knowledge about microbial diversity and their roles involved in fermentation is still fragmentary and not systematic enough. Therefore, in this review, the dominant microorganism species involved in the stages of alcoholic fermentation and acetic acid fermentation of dissimilar vinegars were summarized. We also summarized various physicochemical properties and crucial compounds in disparate types of vinegar. Furthermore, the merits and drawbacks of vital fermentation methods were generalized. Finally, we described in detail the relationships among microbial diversity, raw materials, fermentation methods, physicochemical properties, compounds, functionality, and final quality of vinegar. The integration of this information can provide us a detailed map about the microbial diversity and function involved in vinegar fermentation.

Microbial reverse-electrodialysis chemical-production cell for acid and alkali production

KAUST Repository

Zhu, Xiuping; Hatzell, Marta C.; Cusick, Roland D.; Logan, Bruce E.

2013-01-01

A new type of bioelectrochemical system, called a microbial reverse-electrodialysis chemical-production cell (MRCC), was developed to produce acid and alkali using energy derived from organic matter (acetate) and salinity gradients (NaCl solutions

Diversity of nitrite reductase genes (nirS) in the denitrifying water column of the coastal Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Jayakumar, D.A.; Francis, C.A.; Naqvi, S.W.A.; Ward, B.B.

Denitrification often occurs in the water column, underlying zones of intense productivity and decomposition in upwelling regions. In the denitrifying zone off the southwest coast of India, high concentrations of nitrite (greater than 15 mu M...

Convergent development of anodic bacterial communities in microbial fuel cells.

KAUST Repository

Yates, Matthew D

2012-05-10

Microbial fuel cells (MFCs) are often inoculated from a single wastewater source. The extent that the inoculum affects community development or power production is unknown. The stable anodic microbial communities in MFCs were examined using three inocula: a wastewater treatment plant sample known to produce consistent power densities, a second wastewater treatment plant sample, and an anaerobic bog sediment. The bog-inoculated MFCs initially produced higher power densities than the wastewater-inoculated MFCs, but after 20 cycles all MFCs on average converged to similar voltages (470±20 mV) and maximum power densities (590±170 mW m(-2)). The power output from replicate bog-inoculated MFCs was not significantly different, but one wastewater-inoculated MFC (UAJA3 (UAJA, University Area Joint Authority Wastewater Treatment Plant)) produced substantially less power. Denaturing gradient gel electrophoresis profiling showed a stable exoelectrogenic biofilm community in all samples after 11 cycles. After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%). While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses. These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.

Microbial population dynamics during startup of a full-scale anaerobic digester treating industrial food waste in Kyoto eco-energy project.

Science.gov (United States)

Ike, Michihiko; Inoue, Daisuke; Miyano, Tomoki; Liu, Tong Tong; Sei, Kazunari; Soda, Satoshi; Kadoshin, Shiro

2010-06-01

The microbial community in a full-scale anaerobic digester (2300m3) treating industrial food waste in the Kyoto Eco-Energy Project was analyzed using terminal restriction fragment length polymorphism for eubacterial and archaeal 16S rRNA genes. Both thermophilic and mesophilic sludge of treated swine waste were seeded to the digestion tank. During the 150-day startup period, coffee grounds as a main food waste, along with potato, kelp and boiled beans, tofu, bean curd lees, and deep-fried bean curd were fed to the digestion process step-by-step (max. 40t/d). Finally, the methane yield reached 360m3/t-feed with 40days' retention time, although temporary accumulation of propionate was observed. Eubacterial communities that formed in the thermophilic digestion tank differed greatly from both thermophilic and mesophilic types of seed sludge. Results suggest that the Actinomyces/Thermomonospora and Ralstonia/Shewanella were contributors for hydrolyzation and degradation of food waste into volatile fatty acids. Acetate-utilizing methanogens, Methanosaeta, were dominant in seed sludges of both types, but they decreased drastically during processing in the digestion tank. Methanosarcina and Methanobrevibacter/Methanobacterium were, respectively, possible main contributors for methane production from acetate and H2 plus CO2. Copyright 2010 Elsevier Ltd. All rights reserved.

Biogeochemical reactive-transport modelling of the interactions of medium activity long-lived nuclear waste in fractured argillite and the effect on redox conditions

International Nuclear Information System (INIS)

Small, J.S.; Steele, H.; Kwong, S.; Albrecht, A.

2010-01-01

-surface LLW disposal has been applied to the geological disposal of organic containing MAVL. The study uses microbial kinetic data from studies of LLW degradation, but considers the physical and chemical conditions relevant to the disposal of bituminous waste in the argillaceous (clay) Callovian-Oxfordian (COx) formation at the Meuse/Haute-Marne Site in Eastern France. The objective of the modelling being to scope out the potential microbial activity that may develop in experimental systems that test and investigate the processes controlling microbial activity and redox conditions in the EDZ. The results presented examine the microbial activity that may develop through interaction of a contaminant source containing soluble organics, nitrate, and sulphate with the COx. Processes are modelled representing a column experiment, where reaction-transport coupling effects may occur in open fractures or in regions of intact COx, where diffusion controls transport of chemical species. One of the main processes examined in the model is the overall denitrification process to form N 2 gas from soluble nitrate. Microbial denitrifiers included groups that consume organics, and others that consume hydrogen as electron donors. In the case of organic denitrifiers soluble organics (represented by acetate) are considered in the degradation products of bitumen and also present at lower concentrations in the COx (equivalent to 9 x 105 mol/l acetate). Initially transport of nitrate is largely unaffected by the microbial processes, but after a lag phase of 0.2 y denitrification becomes established. Diffusion of nitrate into the COx is observed. Breakthrough of the acetate concentration is similar to that for nitrate although an excess of acetate is required due to the utilisation of acetate as a carbon source for microbial growth, and this is the reason why incomplete nitrate reduction occurs. The model simulates that denitrification consumes the organic electron donor present in the COx. The GRM

Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics

DEFF Research Database (Denmark)

Pellicer i Nàcher, Carles; Franck, Stephanie; Gülay, Arda

2014-01-01

Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration...... (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r......-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal....

Who's coming to dinner? Microbial phylogenetic analyses of various subsurface petroleum well environments for MEOR applications

Energy Technology Data Exchange (ETDEWEB)

Keeler, Sharon J.; Fallon, Robert; Jackson, Scott; Zhang, Shiping; Tomb, Jean-Francois; Miller, Mark A.; Rees, Bethany [Central Research and Development (Canada)

2011-07-01

This paper discussed the microbial phylogenetic analyses of various subsurface petroleum well environments for microbial-enhanced oil recovery (MEOR) applications. The objective is to add nutrients and microbes to injection water. Close to 47,000 compounds are present in petroleum and most of them are polyaromatic hydrocarbons (PAHs). Microbes that can predominate the biomass produced and the over all bioactivity are needed. Changing the electron acceptor modifies the microbial community. Characterization of microbial diversity in production water with two independent molecular methods is shown. The geology of well systems in North America was analyzed; the analyses and the results are given. Summarizing the North Slope reservoir system phylogenetics, it can be said that many genera found in association with other petroleum environments suggest they are autocthonous and transiently very high levels of acetate signify a mutual metabolic codependency on the amount of acetate present in the system.

Microbial diversity and metabolite composition of Belgian red-brown acidic ales.

Science.gov (United States)

Snauwaert, Isabel; Roels, Sanne P; Van Nieuwerburg, Filip; Van Landschoot, Anita; De Vuyst, Luc; Vandamme, Peter

2016-03-16

Belgian red-brown acidic ales are sour and alcoholic fermented beers, which are produced by mixed-culture fermentation and blending. The brews are aged in oak barrels for about two years, after which mature beer is blended with young, non-aged beer to obtain the end-products. The present study evaluated the microbial community diversity of Belgian red-brown acidic ales at the end of the maturation phase of three subsequent brews of three different breweries. The microbial diversity was compared with the metabolite composition of the brews at the end of the maturation phase. Therefore, mature brew samples were subjected to 454 pyrosequencing of the 16S rRNA gene (bacteria) and the internal transcribed spacer region (yeasts) and a broad range of metabolites was quantified. The most important microbial species present in the Belgian red-brown acidic ales investigated were Pediococcus damnosus, Dekkera bruxellensis, and Acetobacter pasteurianus. In addition, this culture-independent analysis revealed operational taxonomic units that were assigned to an unclassified fungal community member, Candida, and Lactobacillus. The main metabolites present in the brew samples were L-lactic acid, D-lactic acid, and ethanol, whereas acetic acid was produced in lower quantities. The most prevailing aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, and ethyl octanoate, which might be of impact on the aroma of the end-products. Copyright © 2016 Elsevier B.V. All rights reserved.

[Effect of short-time drought process on denitrifying bacteria abundance and N2O emission in paddy soil].

Science.gov (United States)

Lu, Jing; Liu, Jin-Bo; Sheng, Rong; Liu, Yi; Chen, An-Lei; Wei, Wen-Xue

2014-10-01

In order to investigate the impact of drying process on greenhouse gas emissions and denitrifying microorganisms in paddy soil, wetting-drying process was simulated in laboratory conditions. N2O flux, redox potential (Eh) were monitored and narG- and nosZ-containing denitrifiers abundances were determined by real-time PCR. N2O emission was significantly increased only 4 h after drying process began, and it was more than 6 times of continuous flooding (CF) at 24 h. In addition, narG and nosZ gene abundances were increased rapidly with the drying process, and N2O emission flux was significantly correlated with narG gene abundance (P driving microorganisms which caused the N2O emission in the short-time drought process in paddy soil.

Toxic effects exerted on methanogenic, nitrifying and denitrifying bacteria by chemicals used in a milk analysis laboratory

NARCIS (Netherlands)

Lopez-Fiuza, J.; Buys, B.; Mosquera-Corral, A.; Omil, F.; Mendez, R.

2002-01-01

The toxic effects caused by the chemicals contained in wastewaters generated by laboratories involved in raw milk analyses were assessed using batch assays. These assays were carried out separately with methanogenic, ammonium-oxidizing, nitrite-oxidizing and denitrifying bacteria. Since sodium azide

Effects of dairy manure management in annual and perennial cropping systems on soil microbial communities associated with in situ N2O fluxes

Science.gov (United States)

Dunfield, Kari; Thompson, Karen; Bent, Elizabeth; Abalos, Diego; Wagner-Riddle, Claudia

2016-04-01

Liquid dairy manure (LDM) application and ploughing events may affect soil microbial community functioning differently between perennial and annual cropping systems due to plant-specific characteristics stimulating changes in microbial community structure. Understanding how these microbial communities change in response to varied management, and how these changes relate to in situ N2O fluxes may allow the creation of predictive models for use in the development of best management practices (BMPs) to decrease nitrogen (N) losses through choice of crop, plough, and LDM practices. Our objectives were to contrast changes in the population sizes and community structures of genes associated with nitrifier (amoA, crenamoA) and denitrifier (nirK, nirS, nosZ) communities in differently managed annual and perennial fields demonstrating variation in N2O flux, and to determine if differences in these microbial communities were linked to the observed variation in N2O fluxes. Soil was sampled in 2012 and in 2014 in a 4-ha spring-applied LDM grass-legume (perennial) plot and two 4-ha corn (annual) treatments under fall or spring LDM application. Soil DNA was extracted and used to target N-cycling genes via qPCR (n=6) and for next-generation sequencing (Illumina Miseq) (n=3). Significantly higher field-scale N2O fluxes were observed in the annual plots compared to the perennial system; however N2O fluxes increased after plough down of the perennial plot. Nonmetric multidimensional scaling (NMS) indicated differences in N-cycling communities between annual and perennial cropping systems, and some communities became similar between annual and perennial plots after ploughing. Shifts in these communities demonstrated relationships with agricultural management, which were associated with differences in N2O flux. Indicator species analysis was used to identify operational taxonomic units (OTUs) most responsible for community shifts related to management. Nitrifying and denitrifying soil

Effects of microbial processes on gas generation under expected WIPP repository conditions: Annual report through 1992

International Nuclear Information System (INIS)

Francis, A.J.; Gillow, J.B.

1993-09-01

Microbial processes involved in gas generation from degradation of the organic constituents of transuranic waste under conditions expected at the Waste Isolation Pilot Plant (WIPP) repository are being investigated at Brookhaven National Laboratory. These laboratory studies are part of the Sandia National Laboratories -- WIPP Gas Generation Program. Gas generation due to microbial degradation of representative cellulosic waste was investigated in short-term ( 6 months) experiments by incubating representative paper (filter paper, paper towels, and tissue) in WIPP brine under initially aerobic (air) and anaerobic (nitrogen) conditions. Samples from the WIPP surficial environment and underground workings harbor gas-producing halophilic microorganisms, the activities of which were studied in short-term experiments. The microorganisms metabolized a variety of organic compounds including cellulose under aerobic, anaerobic, and denitrifying conditions. In long-term experiments, the effects of added nutrients (trace amounts of ammonium nitrate, phosphate, and yeast extract), no nutrients, and nutrients plus excess nitrate on gas production from cellulose degradation

Seasonal variations of nitrate reducing and denitrifying bacteria utilizing hexadecane in Mandovi estuary, Goa, West Coast of India

Digital Repository Service at National Institute of Oceanography (India)

Sousa, T.D.; Ingole, B.; Sousa, S.D.; Bhosle, S.

> cfu/ml on minimal media containing hexadecane as the sole carbon source. Highest bacterial counts were obtained during the monsoons. 22% of bacteria capable of hexadecane utilization were nitrate reducing and 12% were denitrifying. 29...

Carbon nanotube-coated macroporous sponge for microbial fuel cell electrodes

KAUST Repository

Xie, Xing

2012-01-01

The materials that are used to make electrodes and their internal structures significantly affect microbial fuel cell (MFC) performance. In this study, we describe a carbon nanotube (CNT)-sponge composite prepared by coating a sponge with CNTs. Compared to the CNT-coated textile electrodes evaluated in prior studies, CNT-sponge electrodes had lower internal resistance, greater stability, more tunable and uniform macroporous structure (pores up to 1 mm in diameter), and improved mechanical properties. The CNT-sponge composite also provided a three-dimensional scaffold that was favorable for microbial colonization and catalytic decoration. Using a batch-fed H-shaped MFC outfitted with CNT-sponge electrodes, an areal power density of 1.24 W m -2 was achieved when treating domestic wastewater. The maximum volumetric power density of a continuously fed plate-shaped MFC was 182 W m -3. To our knowledge, these are the highest values obtained to date for MFCs fed domestic wastewater: 2.5 times the previously reported maximum areal power density and 12 times the previously reported maximum volumetric power density. © 2011 The Royal Society of Chemistry.

Simultaneous enrichment of denitrifying anaerobic methane-oxidizing microorganisms and anammox bacteria in a hollow-fiber membrane biofilm reactor.

Science.gov (United States)

Ding, Zhao-Wei; Lu, Yong-Ze; Fu, Liang; Ding, Jing; Zeng, Raymond J

2017-01-01

In this study, the coculture system of denitrifying anaerobic methane oxidation (DAMO) microbes and anaerobic ammonium oxidation (anammox) bacteria was successfully enriched in a hollow-fiber membrane biofilm reactor (HfMBR) using freshwater sediment as the inoculum. The maximal removal rates of nitrate and ammonium were 78 mg N/L/day (131 mg N/m 2 /day) and 26 mg N/L/day (43 mg N/m 2 /day), respectively. Due to the high rate of methane mass transfer in HfMBR, the activity of DAMO archaea continued to increase during the enrichment period, indicating that HfMBR could be a powerful tool to enrich DAMO microorganisms. Effects of partial methane pressure, temperature, and pH on the cocultures were obvious. However, the microbial activity in HfMBR could be recovered quickly after the shock change of environmental factors. Furthermore, the result also found that DAMO bacteria likely had a stronger competitive advantage than anammox bacteria under the operating conditions in this study. High-throughput sequencing 16S rRNA genes illustrated that the dominant microbes were NC10, Euryarchaeota, Proteobacteria, Planctomycetes, and Chlorobi with relative abundance of 38.8, 26.2, 13.78, 6.2, and 3.6 %, respectively.

Supportive use of megestrol acetate in patients with head and neck cancer during radio(chemo)therapy

International Nuclear Information System (INIS)

Fietkau, R.; Riepl, M.; Sauer, R.; Kettner, H.

1997-01-01

To study the supportive effect of megestrol acetate during intensive combined modality treatment, a randomised, double-blind, placebo-controlled study was performed in patients with head and neck cancer. The patients received either 160 mg of megestrol acetate daily or placebo during radio(chemo)therapy and for up to 6 weeks thereafter. The nutritional status as measured by anthropometric and biochemical parameters and the subjective quality of life were assessed prior to therapy, at weeks 1, 4 and 6 of radiotherapy and 12 and 18 weeks from the start of therapy. 61 of 64 patients were evaluable. In the control group (n = 30), the nutritional parameters deteriorated during therapy and were fully restored during follow-up. By contrast, the patients treated with megestrol acetate (n = 31) could maintain their baseline values. The difference between the groups was most pronounced in patients taking food per mouth (weight loss during treatment: control group: 4.1 kg; megestrol acetate group: 0.8 kg, P = 0.0004), but was not significant in patients fed via percutaneous endoscopically guided gastrostomy (PEG). Subjective quality of life remained constant in the megestrol acetate group while it decreased in the control group. However, differences were not statistically significant. Megestrol acetate prevents further deterioration of nutritional status during radio(chemo)therapy and may have an impact on subjective quality of life. (Author)

Supportive use of megestrol acetate in patients with head and neck cancer during radio(chemo)therapy

Energy Technology Data Exchange (ETDEWEB)

Fietkau, R.; Riepl, M.; Sauer, R. [Erlangen-Nuernberg Univ., Erlangen (Germany); Kettner, H. [Bristol Arzneimittel GmbH, Muenchen (Germany). Medical Div.; Hinke, A. [Wissenschaftlicher Service Pharma, Monheim (Germany)

1997-01-01

To study the supportive effect of megestrol acetate during intensive combined modality treatment, a randomised, double-blind, placebo-controlled study was performed in patients with head and neck cancer. The patients received either 160 mg of megestrol acetate daily or placebo during radio(chemo)therapy and for up to 6 weeks thereafter. The nutritional status as measured by anthropometric and biochemical parameters and the subjective quality of life were assessed prior to therapy, at weeks 1, 4 and 6 of radiotherapy and 12 and 18 weeks from the start of therapy. 61 of 64 patients were evaluable. In the control group (n = 30), the nutritional parameters deteriorated during therapy and were fully restored during follow-up. By contrast, the patients treated with megestrol acetate (n = 31) could maintain their baseline values. The difference between the groups was most pronounced in patients taking food per mouth (weight loss during treatment: control group: 4.1 kg; megestrol acetate group: 0.8 kg, P = 0.0004), but was not significant in patients fed via percutaneous endoscopically guided gastrostomy (PEG). Subjective quality of life remained constant in the megestrol acetate group while it decreased in the control group. However, differences were not statistically significant. Megestrol acetate prevents further deterioration of nutritional status during radio(chemo)therapy and may have an impact on subjective quality of life. (Author).

Co-effects of pyrene and nitrate on the activity and abundance of soil denitrifiers under anaerobic condition.

Science.gov (United States)

Zhou, Zhi-Feng; Yao, Yan-Hong; Wang, Ming-Xia; Zuo, Xiao-Hu

2017-10-01

It has previously been confirmed that polycyclic aromatic hydrocarbons (PAHs) could be degraded by soil microbes coupling with denitrification, but the relationships among soil denitrifiers, PAHs, and nitrate under obligate anaerobic condition are still unclear. Here, co-effects of pyrene and nitrate on the activity and abundance of soil denitrifiers were investigated through a 45-day incubation experiment. Two groups of soil treatments with (N 30 ) and without (N 0 ) nitrate (30 mg kg -1 dry soil) amendment were conducted, and each group contained three treatments with different pyrene concentrations (0, 30, and 60 mg kg -1 dry soil denoted as P 0 , P 30 , and P 60 , respectively). The pyrene content, abundances of denitrification concerning genes (narG, periplasmic nitrate reductase gene; nirS, cd 1 -nitrite reductase gene; nirK, copper-containing nitrite reductase gene), and productions of N 2 O and CO 2 were measured at day 3, 14, 28, and 45, and the bacterial community structures in four represented treatments (N 0 P 0 , N 0 P 60 , N 30 P 0 , and N 30 P 60 ) were analyzed at day 45. The results indicated that the treatments with higher pyrene concentration had higher final pyrene removal rates than the treatments with lower pyrene concentration. Additionally, intensive emission of N 2 O was detected in all treatments only at day 3, but a continuous production of CO 2 was measured in each treatment during the incubation. Nitrate amendment could enhance the activity of soil denitrifiers, and be helpful for soil microbes to sustain their activity. While pyrene seemed had no influence on the productions of N 2 O and CO 2 , and amendment with pyrene or nitrate both had no obvious effect on abundances of denitrification concerning genes. Furthermore, it was nitrate but not pyrene had an obvious influence on the community structure of soil bacteria. These results revealed that, under anaerobic condition, the activity and abundance of soil denitrifiers both were

Phylogenetic characterization of fecal microbial communities of dogs fed diets with or without supplemental dietary fiber using 454 pyrosequencing.

Directory of Open Access Journals (Sweden)

Ingmar S Middelbos

Full Text Available BACKGROUND: Dogs suffer from many of the same maladies as humans that may be affected by the gut microbiome, but knowledge of the canine microbiome is incomplete. This work aimed to use 16S rDNA tag pyrosequencing to phylogenetically characterize hindgut microbiome in dogs and determine how consumption of dietary fiber affects community structure. PRINCIPAL FINDINGS: Six healthy adult dogs were used in a crossover design. A control diet without supplemental fiber and a beet pulp-supplemented (7.5% diet were fed. Fecal DNA was extracted and the V3 hypervariable region of the microbial 16S rDNA gene amplified using primers suitable for 454-pyrosequencing. Microbial diversity was assessed on random 2000-sequence subsamples of individual and pooled DNA samples by diet. Our dataset comprised 77,771 reads with an average length of 141 nt. Individual samples contained approximately 129 OTU, with Fusobacteria (23-40% of reads, Firmicutes (14-28% of reads and Bacteroidetes (31-34% of reads being co-dominant phyla. Feeding dietary fiber generally decreased Fusobacteria and increased Firmicutes, but these changes were not equally apparent in all dogs. UniFrac analysis revealed that structure of the gut microbiome was affected by diet and Firmicutes appeared to play a strong role in by-diet clustering. CONCLUSIONS: Our data suggest three co-dominant bacterial phyla in the canine hindgut. Furthermore, a relatively small amount of dietary fiber changed the structure of the gut microbiome detectably. Our data are among the first to characterize the healthy canine gut microbiome using pyrosequencing and provide a basis for studies focused on devising dietary interventions for microbiome-associated diseases.

Microbial biogeography of San Francisco Bay sediments

Science.gov (United States)

Lee, J. A.; Francis, C. A.

2014-12-01

The largest estuary on the west coast of North America, San Francisco Bay is an ecosystem of enormous biodiversity, and also enormous human impact. The benthos has experienced dredging, occupation by invasive species, and over a century of sediment input as a result of hydraulic mining. Although the Bay's great cultural and ecological importance has inspired numerous surveys of the benthic macrofauna, to date there has been almost no investigation of the microbial communities on the Bay floor. An understanding of those microbial communities would contribute significantly to our understanding of both the biogeochemical processes (which are driven by the microbiota) and the physical processes (which contribute to microbial distributions) in the Bay. Here, we present the first broad survey of bacterial and archaeal taxa in the sediments of the San Francisco Bay. We conducted 16S rRNA community sequencing of bacteria and archaea in sediment samples taken bimonthly for one year, from five sites spanning the salinity gradient between Suisun and Central Bay, in order to capture the effect of both spatial and temporal environmental variation on microbial diversity. From the same samples we also conducted deep sequencing of a nitrogen-cycling functional gene, nirS, allowing an assessment of evolutionary diversity at a much finer taxonomic scale within an important and widespread functional group of bacteria. We paired these sequencing projects with extensive geochemical metadata as well as information about macrofaunal distribution. Our data reveal a diversity of distinct biogeographical patterns among different taxa: clades ubiquitous across sites; clades that respond to measurable environmental drivers; and clades that show geographical site-specificity. These community datasets allow us to test the hypothesis that salinity is a major driver of both overall microbial community structure and community structure of the denitrifying bacteria specifically; and to assess

Diversity of Nitrate-Reducing and Denitrifying Bacteria in a Marine Aquaculture Biofilter and their Response to Sulfide

DEFF Research Database (Denmark)

Krieger, Bärbel; Schwermer, Carsten U.; Rezakhani, Nastaran

2006-01-01

with Alphaproteobacteria but also including Beta- and Gammaproteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. The diversity of the isolates was compared to the cultivation-independent diversity of nitrate-reducing and denitrifying bacteria based on narG and nosZ as functional marker genes. Growth experiments...

Prebiotic milk oligosaccharides prevent development of obese phenotype, impairment of gut permeability, and microbial dysbiosis in high fat-fed mice.

Science.gov (United States)

Hamilton, M Kristina; Ronveaux, Charlotte C; Rust, Bret M; Newman, John W; Hawley, Melissa; Barile, Daniela; Mills, David A; Raybould, Helen E

2017-05-01

Microbial dysbiosis and increased intestinal permeability are targets for prevention or reversal of weight gain in high-fat (HF) diet-induced obesity (DIO). Prebiotic milk oligosaccharides (MO) have been shown to benefit the host intestine but have not been used in DIO. We hypothesized that supplementation with bovine MO would prevent the deleterious effect of HF diet on the gut microbiota and intestinal permeability and attenuate development of the obese phenotype. C57BL/6 mice were fed a control diet, HF (40% fat/kcal), or HF + prebiotic [6%/kg bovine milk oligosaccharides (BMO) or inulin] for 1, 3, or 6 wk. Gut microbiota and intestinal permeability were assessed in the ileum, cecum, and colon. Addition of BMO to the HF diet significantly attenuated weight gain, decreased adiposity, and decreased caloric intake; inulin supplementation also lowered weight gain and adiposity, but this did not reach significance. BMO and inulin completely abolished the HF diet-induced increase in paracellular and transcellular permeability in the small and large intestine. Both BMO and inulin increased abundance of beneficial microbes Bifidobacterium and Lactobacillus in the ileum. However, inulin supplementation altered phylogenetic diversity and decreased species richness. We conclude that addition of BMO to the HF diet completely prevented increases in intestinal permeability and microbial dysbiosis and was partially effective to prevent weight gain in DIO. NEW & NOTEWORTHY This study provides the first report of the effects of prebiotic bovine milk oligosaccharides on the host phenotype of high-fat diet-induced obesity in mice. Copyright © 2017 the American Physiological Society.

Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

Energy Technology Data Exchange (ETDEWEB)

Kerkhof, L.; Williams, K.H.; Long, P.E.; McGuinness, L.

2011-02-21

Previous experiments at the Rifle, Colorado Integrated Field Research Challenge (IFRC) site demonstrated that field-scale addition of acetate to groundwater reduced the ambient soluble uranium concentration. In this report, sediment samples collected before and after acetate field addition were used to assess the active microbes via {sup 13}C acetate stable isotope probing on 3 phases [coarse sand, fines (8-approximately 150 {micro}m), groundwater (0.2-8 {micro}m)] over a 24-day time frame. TRFLP results generally indicated a stronger signal in {sup 13}C-DNA in the 'fines' fraction compared to the sand and groundwater. Before the field-scale acetate addition, a Geobacter-like group primarily synthesized {sup 13}C-DNA in the groundwater phase, an alpha Proteobacterium primarily grew on the fines/sands, and an Acinetobacter sp. and Decholoromonas-like OTU utilized much of the {sup 13}C acetate in both groundwater and particle-associated phases. At the termination of the field-scale acetate addition, the Geobacter-like species was active on the solid phases rather than the groundwater, while the other bacterial groups had very reduced newly synthesized DNA signal. These findings will help to delineate the acetate utilization patterns of bacteria in the field and can lead to improved methods for stimulating distinct microbial populations in situ.

Microbial production of volatile sulphur compounds in the large intestine of pigs fed two different diets.

Science.gov (United States)

Poulsen, H V; Jensen, B B; Finster, K; Spence, C; Whitehead, T R; Cotta, M A; Canibe, N

2012-07-01

  To investigate the production of volatile sulphur compounds (VSC) in the segments of the large intestine of pigs and to assess the impact of diet on this production.   Pigs were fed two diets based on either wheat and barley (STD) or wheat and dried distillers grains with solubles (DDGS). Net production of VSC and potential sulphate reduction rate (SRR) (sulphate saturated) along the large intestine were determined by means of in vitro incubations. The net production rate of hydrogen sulphide and potential SRR increased from caecum towards distal colon and were significantly higher in the STD group. Conversely, the net methanethiol production rate was significantly higher in the DDGS group, while no difference was observed for dimethyl sulphide. The number of sulphate-reducing bacteria and total bacteria were determined by quantitative PCR and showed a significant increase along the large intestine, whereas no diet-related differences were observed.   VSC net production varies widely throughout the large intestine of pigs and the microbial processes involved in this production can be affected by diet.   This first report on intestinal production of all VSC shows both spatial and dietary effects, which are relevant to both bowel disease- and odour mitigation research. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Environmental controls on microbial communities in continental serpentinite fluids

Directory of Open Access Journals (Sweden)

Melitza eCrespo-Medina

2014-11-01

Full Text Available Geochemical reactions associated with serpentinization alter the composition of dissolved organic compounds in circulating fluids and potentially liberate mantle-derived carbon and reducing power to support subsurface microbial communities. Previous studies have identified Betaproteobacteria from the order Burkholderiales and bacteria from the order Clostridiales as key components of the serpentinite–hosted microbiome, however there is limited knowledge of their metabolic capabilities or growth characteristics. In an effort to better characterize microbial communities, their metabolism, and factors limiting their activities, microcosm experiments were designed with fluids collected from several monitoring wells at the Coast Range Ophiolite Microbial Observatory (CROMO in northern California during expeditions in March and August 2013. The incubations were initiated with a hydrogen atmosphere and a variety of carbon sources (carbon dioxide, methane, acetate and formate, with and without the addition of nutrients and electron acceptors. Growth was monitored by direct microscopic counts; DNA yield and community composition was assessed at the end of the three month incubation. For the most part, results indicate that bacterial growth was favored by the addition of acetate and methane, and that the addition of nutrients and electron acceptors had no significant effect on microbial growth, suggesting no nutrient- or oxidant-limitation. However the addition of sulfur amendments led to different community compositions. The dominant organisms at the end of the incubations were closely related to Dethiobacter sp. and to the family Comamonadaceae, which are also prominent in culture-independent gene sequencing surveys. These experiments provide one of first insights into the biogeochemical dynamics of the serpentinite subsurface environment and will facilitate experiments to trace microbial activities in serpentinizing ecosystems.

Ruminal changes in monensin- and lasalocid-fed cattle grazing bloat-provocative alfalfa pasture.

Science.gov (United States)

Katz, M P; Nagaraja, T G; Fina, L R

1986-10-01

Microbial and fermentation changes in the rumen in monensin- and lasalocid-fed cattle grazing bloat-provocative alfalfa pasture were studied using genetically bloat-susceptible, ruminally-cannulated adult cattle. Monensin at .66 and .99 mg/kg body weight daily reduced the severity of legume bloat by 41 and 73%, respectively. The same doses of lasalocid reduced bloat by 25 and 12%. Comparison of ruminal contents from animals before treatment with ruminal contents from antibiotic-treated animals showed no differences in pH, ammonia, soluble N, soluble carbohydrate, ethanol-precipitable slime and anaerobic bacterial counts. Monensin treatment decreased protozoal numbers and microbial activity, as evidenced by lower gas production from in vitro fermentation of ground alfalfa hay when compared to pretreatment. Lasalocid had no effect on protozoal counts and in vitro gas production. Addition of monensin or lasalocid (12 micrograms/ml) to in vitro fermentation of chopped, fresh alfalfa reduced microbial activity as evidenced by higher soluble N, lower ammonia concentration and decreased gas production. Monensin reduced the amount of ethanol-precipitable slime and protozoal numbers. Reduction in the severity of bloat when monensin was fed appears to be due to decreased protozoal numbers, which resulted in decreased gas production. Lasalocid did not reduce legume bloat because of its minimal effect on the ruminal protozoa.

Hydrothermal Synthesis of Nanostructured Manganese Oxide as Cathodic Catalyst in a Microbial Fuel Cell Fed with Leachate

Science.gov (United States)

Haoran, Yuan; Lifang, Deng; Tao, Lu; Yong, Chen

2014-01-01

Much effort has been devoted to the synthesis of novel nanostructured MnO2 materials because of their unique properties and potential applications as cathode catalyst in Microbial fuel cell. Hybrid MnO2 nanostructures were fabricated by a simple hydrothermal method in this study. Their crystal structures, morphology, and electrochemical characters were carried out by FESEM, N2-adsorption-desorption, and CV, indicating that the hydrothermally synthesized MnO2 (HSM) was structured by nanorods of high aspect ratio and multivalve nanoflowers and more positive than the naturally synthesized MnO2 (NSM), accompanied by a noticeable increase in oxygen reduction peak current. When the HSM was employed as the cathode catalyst in air-cathode MFC which fed with leachate, a maximum power density of 119.07 mW/m2 was delivered, 64.68% higher than that with the NSM as cathode catalyst. Furthermore, the HSM via a 4-e pathway, but the NSM via a 2-e pathway in alkaline solution, and as 4-e pathway is a more efficient oxygen reduction reaction, the HSM was more positive than NSM. Our study provides useful information on facile preparation of cost-effective cathodic catalyst in air-cathode MFC for wastewater treatment. PMID:24723824

Determination of Microbial Nitrogen Production by Using Urinary Allantoin and Blood Metabolite Concentrate in Growing Brahman Cattle Fed the Different Proportion of Roughage and Concentrate in Diets

International Nuclear Information System (INIS)

Suthikrai, Wanvipa; Usawang, Sungwon; Kijsamrej, Suriya; Sophon, Sunpetch; Jetana, Thongsuk

2003-06-01

Determination of microbial nitrogen synthesis by using urinary allantoin and blood metabolite for evaluating the efficiency of feed utilization, in this study was conducted by using four Brahman bulls (about 1 year old). Animals were fed ad libitum with 4 fixed diets of four combinations of pineapple fibre (P) and concentrate (C) in the proportions, on dry matter basis of 0.8:0.2 (P80:C20), 0.6:0.04(P60:C40), 0.4:0.6(P40:C60) and 0.2:0.8 (P20:C80). The experiment was designed as a 4x4 Latin square design The Results showed that increasing in the proportion of concentrate linearly increased the rumen microbial nitrogen production (p<0.001), the concentrations of Insulin and urea-N in plasma and the concentration of urea-N in the urine, but not affected on the concentrations of glucose and creatinine in plasma. In conclusion, the using of allantoin urinary associated with blood metabolite can evaluate the accuracy in evaluation of feed utilization in Brahman cattle

MbT-Tool: An open-access tool based on Thermodynamic Electron Equivalents Model to obtain microbial-metabolic reactions to be used in biotechnological process

Directory of Open Access Journals (Sweden)

Pablo Araujo Granda

2016-01-01

Full Text Available Modelling cellular metabolism is a strategic factor in investigating microbial behaviour and interactions, especially for bio-technological processes. A key factor for modelling microbial activity is the calculation of nutrient amounts and products generated as a result of the microbial metabolism. Representing metabolic pathways through balanced reactions is a complex and time-consuming task for biologists, ecologists, modellers and engineers. A new computational tool to represent microbial pathways through microbial metabolic reactions (MMRs using the approach of the Thermodynamic Electron Equivalents Model has been designed and implemented in the open-access framework NetLogo. This computational tool, called MbT-Tool (Metabolism based on Thermodynamics can write MMRs for different microbial functional groups, such as aerobic heterotrophs, nitrifiers, denitrifiers, methanogens, sulphate reducers, sulphide oxidizers and fermenters. The MbT-Tool's code contains eighteen organic and twenty inorganic reduction-half-reactions, four N-sources (NH4+, NO3−, NO2−, N2 to biomass synthesis and twenty-four microbial empirical formulas, one of which can be determined by the user (CnHaObNc. MbT-Tool is an open-source program capable of writing MMRs based on thermodynamic concepts, which are applicable in a wide range of academic research interested in designing, optimizing and modelling microbial activity without any extensive chemical, microbiological and programing experience.

Microbially induced carbonate precipitation (MICP) by denitrification as ground improvement method - Process control in sand column experiments

Science.gov (United States)

Pham, Vinh; van Paassen, Leon; Nakano, Akiko; Kanayama, Motohei; Heimovaara, Timo

2013-04-01

Calcite precipitation induced by microbes has been proven to be efficient in stabilizing granular soils, especially with urea hydrolysis, as it has been successfully demonstrated in a pilot application 2010. However, as a byproduct highly concentrated ammonium chloride (NH4Cl) solution is produced, which has to be removed and disposed and forms a significant disadvantage of the technique that makes an alternative process like denitrification preferred. The proof of principle of microbially induced calcite precipitation (MICP) by denitrification has been demonstrated by Van Paassen et al (2010) who suggested that instead of producing waste as a byproduct, different pre-treated waste streams could be used as substrates for in situ growth of denitrifying bacteria and simultaneous cementation without producing waste to be removed. In this study sand column experiments are performed in which calcium carbonate was successfully precipitated by indigenous denitrifying micro-organisms, which were supplied weekly with a pulse of a substrate solution containing calcium acetate and calcium nitrate. Besides the production of calcite and the growth of bacteria in biofilms, the reduction of nitrate resulted in the production of (nitrogen) gas. It was observed that this gas partly fills up the pore space and consequently contributed to a reduction of the permeability of the treated sand. The presence of gas in the pore space affected the flow of the injected substrates and influenced to the distribution of calcium carbonate. The effect of the mean particle size (D50) on the flow and transport of solutes and gas in the porous media has been evaluated by treating several columns with varying grain size distribution and comparing the change in permeability after each incubation period and analyzing the distribution of the gas throughout the columns using X-ray computed tomography (CT) scanning. The present results show that there is a considerable decrease of permeability - a

Rumen volatile fatty acids and milk composition from cows fed hay, haylage, or urea-treated corn silage.

Science.gov (United States)

Schingoethe, D J; Voelker, H H; Beardsley, G L; Parsons, J G

1976-05-01

Alfalfa-brome hay, haylage, .5% urea-treated corn silage, or .5% urea plus 1% dried whey-treated corn silage was fed as the only forage to one of four groups of 10 lactating cows per group for a lactation trial of 10 wk. Rumen samples were collected via stomach tube 3 to 4 h after the morning feeding. The pH of the rumen samples from cows fed hay was higher than for cows fed haylage, urea-treated corn silage, and urea-whey corn silage, 6.69 versus 6.36, 6.40, and 6.50. Total volatile fatty acids and propionate were highest from cows fed urea-whey corn silage and were higher on all three fermented forages than cows fed hay. Acetate/propionate ratio was highest from cows fed hay and lowest from cows fed corn silages. Butyrate was highest from cows fed haylage or hay. Milk protein composition was not affected by ration although nonprotein nitrogen of milk was highest from cows fed the urea-treated corn silages. Oleic acid and total unsaturated fatty acids were lowest in milk fat from cows fed hay while palmitic acid was highest from cows fed hay and haylage. These results suggest that type of forage fed may cause small changes in rumen fermentation and in milk composition. The importance of these changes is unknown but may affect properties of dairy products produced from this milk.

THE INCORPORATION OF ACETATE-1-C14 INTO CHOLESTEROL AND FATTY ACIDS BY SURVIVING TISSUES OF NORMAL AND SCORBUTIC GUINEA PIGS

Science.gov (United States)

Bolker, H. I.; Fishman, S.; Heard, R. D. H.; O'Donnell, V. J.; Webb, J. L.; Willis, G. C.

1956-01-01

The synthesis of cholesterol and fatty acids from acetate-l-C14 by the isolated liver, adrenal, and aorta of scorbutic and pair-fed control guinea pigs has been studied. It was found that ascorbic acid deficiency does not affect the rate of incorporation of C14-acetate into cholesterol and fatty acids by the tissues investigated, under our experimental conditions. The relatively high metabolic activity of the artery with regard to cholesterogenesis and lipogenesis was noted. The elevation of serum cholesterol and hexosamine in scurvy has been confirmed. PMID:13286427

Development of a two-stage feeding strategy based on the kind and level of feeding nutrients for improving fed-batch production of L-threonine by Escherichia coli.

Science.gov (United States)

Liu, Shuwen; Liang, Yong; Liu, Qian; Tao, Tongtong; Lai, Shujuan; Chen, Ning; Wen, Tingyi

2013-01-01

Fed-batch fermentation is the predominant method for industrial production of amino acids. In this study, we comprehensively investigated the effects of four kinds of feeding nutrients and developed an accurate optimization strategy for fed-batch production of L-threonine. The production of L-threonine was severely inhibited when cell growth ceased in the bath culture. Similarly, L-threonine production was also associated with cell growth in the carbon-, phosphate-, and sulfate-limited fed-batch cultures, but the accumulation of L-threonine was markedly increased because of the extended production time in the growth stage. Interestingly, auxotrophic amino acid (L-isoleucine)-limited feeding promoted L-threonine production over the non-growth phase. Metabolite analysis indicates that substantial production of acetate and glutamate and the resulting accumulation of ammonium may lead to the inhibition of L-threonine production. During the growth phase, the levels of L-isoleucine were accurately optimized by balancing cell growth and production with Pontryagin's maximum principle, basing on the relationship between the specific growth rate μ and specific production rate ρ. Furthermore, the depletion of L-isoleucine and phosphate at the end of the growth phase favored the synthesis of L-threonine in the subsequent non-growth phase. Combining the two-stage feeding profiles, the final L-threonine concentration and conversion rate were increased by 5.9- and 2.1-fold, respectively, compared to batch processes without feeding control. The identification of efficient feeding nutrient and the development of accurate feeding strategies provide potential guidelines for microbial production of amino acids.

Interaction of unsaturated fat or coconut oil with monensin in lactating dairy cows fed 12 times daily. I. Protozoal abundance, nutrient digestibility, and microbial protein flow to the omasum.

Science.gov (United States)

Reveneau, C; Karnati, S K R; Oelker, E R; Firkins, J L

2012-04-01

Monensin (tradename: Rumensin) should reduce the extent of amino acid deamination in the rumen, and supplemental fat should decrease protozoal abundance and intraruminal N recycling. Because animal-vegetable (AV) fat can be biohydrogenated in the rumen and decrease its effectiveness as an anti-protozoal agent, we included diets supplemented with coconut oil (CNO) to inhibit protozoa. In a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of treatments, 6 rumen-cannulated cows were fed diets without or with Rumensin (12 g/909 kg) and either no fat (control), 5% AV fat, or 5% CNO. The log10 concentrations (cells/mL) of total protozoa were not different between control (5.97) and AV fat (5.95) but were decreased by CNO (4.79; main effect of fat source). Entodinium and Dasytricha decreased as a proportion of total cells from feeding CNO, whereas Epidinium was unchanged in total abundance and thus increased proportionately. Total volatile fatty acid concentration was not affected by diet, but the acetate:propionate ratio decreased for CNO (1.85) versus control (2.95) or AV fat (2.58). Feeding CNO (23.8%) decreased ruminal neutral detergent fiber digestibility compared with control (31.1%) and AV fat (30.5%). The total-tract digestibility of NDF was lower for CNO (45.8%) versus control (57.0%) and AV fat (54.6%), with no difference in apparent organic matter digestibility (averaging 69.8%). The omasal flows of microbial N and non-ammonia N were lower for CNO versus control and AV fat, but efficiency of microbial protein synthesis was not affected. The dry matter intake was 4.5 kg/d lower with CNO, which decreased milk production by 3.1 kg/d. Main effect means of dry matter intake and milk yield tended to decrease by 0.7 and 1.2 kg/d, respectively, when Rumensin was added. Both percentage and production of milk fat decreased for CNO (main effect of fat source). An interaction was observed such that AV decreased milk fat yield more when combined with Rumensin

The electric picnic: synergistic requirements for exoelectrogenic microbial communities

KAUST Repository

Kiely, Patrick D

2011-06-01

Characterization of the various microbial populations present in exoelectrogenic biofilms provides insight into the processes required to convert complex organic matter in wastewater streams into electrical current in bioelectrochemical systems (BESs). Analysis of the community profiles of exoelectrogenic microbial consortia in BESs fed different substrates gives a clearer picture of the different microbial populations present in these exoelectrogenic biofilms. Rapid utilization of fermentation end products by exoelectrogens (typically Geobacter species) relieves feedback inhibition for the fermentative consortia, allowing for rapid metabolism of organics. Identification of specific syntrophic processes and the communities characteristic of these anodic biofilms will be a valuable aid in improving the performance of BESs. © 2011 Elsevier Ltd.

Performance and microbial community of anammox in presence of micro-molecule carbon source.

Science.gov (United States)

He, Shilong; Yang, Wan; Qin, Meng; Mao, Zhen; Niu, Qigui; Han, Ming

2018-08-01

Because ammonium (NH 4 + -N) coexists with organic matter in some wastewaters, the possible adverse influences of organic matter become a major concern in the applications of anaerobic ammonium oxidation (anammox). In this study, the effects of acetate, as a representative of micro-molecule organic matter, on anammox were investigated. Efficient nitrogen removal was realized because denitrifying bacteria and anammox bacteria (AnAOB) had a better synergistic effect under the condition of chemical oxygen demand (COD) concentrations lower than 251 ± 7 mg L -1 . Furthermore, the nitrogen removal efficiency (NRE) decreased to 82.02 ± 3.14% when COD was increased to 730 ± 9 mg L -1 , and effluent free ammonia (FA) reached 21.93 ± 4.71 mg L -1 might be one of factors leading to inhibition. However, the nitrogen-removal contribution rate of anammox remained steady at 61.97 ± 2.84% at COD of 730 ± 9 mg L -1 , which indicated that anammox was still dominant in the system. AnAOB, such as Ca. Kuenenia and Ca. Jettenia, and denitrifying bacteria, such as Denitratisoma and Thauera, were found to coexist in the reactor. Interestingly, Ca. Kuenenia presented in the trend of first decreased then increased with the increasing of organic matter concentration, which might be one of reasons that anammox played an important role in nitrogen removal at high COD concentration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Set anode potentials affect the electron fluxes and microbial community structure in propionate-fed microbial electrolysis cells

KAUST Repository

Rao, Hari Ananda; Katuri, Krishna; Logan, Bruce E.; Saikaly, Pascal

2016-01-01

, but their relative abundance varied among the tested SAPs. Microbial community analysis implies that complete degradation of propionate in all the tested SAPs was facilitated by syntrophic interactions between fermenters and Geobacter at the anode and ferementers

Application of a qualitative image analysis on the evaluation of microbial process parameters of biogas plants; Einsatz einer quantitativen Bildanalyse zur Beurteilung mikrobieller Prozessparameter von Biogasanlagen

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Sung; Scherer, Paul [Hamburg Univ. of Applied Sciences, Hamburg-Bergedorf (Germany). Faculty of Life Sciences

2013-10-01

To evaluate efficiency and microbial activity of biogas or anaerobic waste water treatment plants, the number of microorganisms per gram or per milliliter is supposed to be a crucial factor. Since some years ago our research group at HAW-Hamburg has struggled to develop a simple and rapid technique for quantification and classification of environmental microbes with a semi-automatic digital image analysis. For detection of methanogens, the methanogenic fluorescence coenzyme F420 was used, which represents the vitality of methanogens. Furthermore this technique has been supplemented with morphological classification resulting in a Quantitative Microscopic Fingerprinting (QMF). The technique facilitates to find out microbial reasons for some problems of reactor performances. In addition QMF allows differentiating between H{sub 2}-CO{sub 2} and acetate consuming methanogens according to their morphology. At the moment, this study focusses on some relationships between QMF and plant operation parameters. As an example, a thermophilic biogas plant fed by 65% liquid cow manure, maize silage, grass silage and solid cow manure was analyzed for more than 22 weeks. Here some basic background and methodical procedures were presented as well as validation of this technique. (orig.)

Analysis of the intestinal microbiota of oligo-saccharide fed mice exhibiting reduced resistance to Salmonella infection

DEFF Research Database (Denmark)

Petersen, Anne; Bergström, Anders; Andersen, Jens Bo

2010-01-01

recently demonstrated a reduced resistance to Salmonella infection in mice fed diets containing fructo-oligosaccharides (FOS) or xylo-oligosaccharides (XOS). In the present study, faecal and caecal samples from the same mice were analysed in order to study microbial changes potentially explaining...... the observed effects on the pathogenesis of Salmonella. Denaturing gradient gel electrophoresis revealed that the microbiota in faecal samples from mice fed FOS or XOS were different from faecal samples collected before the feeding trial as well as from faecal profiles generated from control animals...... of short-chain fatty acids was recorded. In conclusion, diets supplemented with FOS or XOS induced a number of microbial changes in the faecal microbiota of mice. The observed effects of XOS were qualitatively similar to those of FOS, but the most prominent bifidogenic effect was seen for XOS. An increased...

Effects of Protease, Phytase and a Bacillus sp. Direct-Fed Microbial on Nutrient and Energy Digestibility, Ileal Brush Border Digestive Enzyme Activity and Cecal Short-Chain Fatty Acid Concentration in Broiler Chickens

Science.gov (United States)

Murugesan, Ganapathi R.; Romero, Luis F.; Persia, Michael E.

2014-01-01

Two experiments were conducted to determine the effects of protease and phytase (PP) and a Bacillus sp. direct-fed microbial (DFM) on dietary energy and nutrient utilization in broiler chickens. In the first experiment, Ross 308 broiler chicks were fed diets supplemented with PP and DFM in a 2×2 factorial arrangement. The 4 diets (control (CON), CON + PP, CON + DFM, and CON + PP + DFM) were fed from 15–21 days of age. In Experiment 1, significant interaction (P≤0.01) between PP and DFM on the apparent ileal digestibility coefficient for starch, crude protein, and amino acid indicated that both additives increased the digestibility. Both additives increased the nitrogen retention coefficient with a significant interaction (P≤0.01). Although no interaction was observed, significant main effects (P≤0.01) for nitrogen-corrected apparent ME (AMEn) for PP or DFM indicated an additive response. In a follow-up experiment, Ross 308 broiler chicks were fed the same experimental diets from 1–21 days of age. Activities of ileal brush border maltase, sucrase, and L-alanine aminopeptidase were increased (P≤0.01) by PP addition, while a trend (P = 0.07) for increased sucrase activity was observed in chickens fed DFM, in Experiment 2. The proportion of cecal butyrate was increased (P≤0.01) by DFM addition. Increased nutrient utilization and nitrogen retention appear to involve separate but complementary mechanisms for PP and DFM, however AMEn responses appear to have separate and additive mechanisms. PMID:25013936

Pyrosequencing analysis yields comprehensive assessment of microbial communities in pilot-scale two-stage membrane biofilm reactors.

Science.gov (United States)

Ontiveros-Valencia, Aura; Tang, Youneng; Zhao, He-Ping; Friese, David; Overstreet, Ryan; Smith, Jennifer; Evans, Patrick; Rittmann, Bruce E; Krajmalnik-Brown, Rosa

2014-07-01

We studied the microbial community structure of pilot two-stage membrane biofilm reactors (MBfRs) designed to reduce nitrate (NO3(-)) and perchlorate (ClO4(-)) in contaminated groundwater. The groundwater also contained oxygen (O2) and sulfate (SO4(2-)), which became important electron sinks that affected the NO3(-) and ClO4(-) removal rates. Using pyrosequencing, we elucidated how important phylotypes of each "primary" microbial group, i.e., denitrifying bacteria (DB), perchlorate-reducing bacteria (PRB), and sulfate-reducing bacteria (SRB), responded to changes in electron-acceptor loading. UniFrac, principal coordinate analysis (PCoA), and diversity analyses documented that the microbial community of biofilms sampled when the MBfRs had a high acceptor loading were phylogenetically distant from and less diverse than the microbial community of biofilm samples with lower acceptor loadings. Diminished acceptor loading led to SO4(2-) reduction in the lag MBfR, which allowed Desulfovibrionales (an SRB) and Thiothrichales (sulfur-oxidizers) to thrive through S cycling. As a result of this cooperative relationship, they competed effectively with DB/PRB phylotypes such as Xanthomonadales and Rhodobacterales. Thus, pyrosequencing illustrated that while DB, PRB, and SRB responded predictably to changes in acceptor loading, a decrease in total acceptor loading led to important shifts within the "primary" groups, the onset of other members (e.g., Thiothrichales), and overall greater diversity.

Convergent evolution of a modified, acetate-driven TCA cycle in bacteria.

Science.gov (United States)

Kwong, Waldan K; Zheng, Hao; Moran, Nancy A

2017-04-28

The tricarboxylic acid (TCA) cycle is central to energy production and biosynthetic precursor synthesis in aerobic organisms. There are few known variations of a complete TCA cycle, with the common notion being that the enzymes involved have already evolved towards optimal performance. Here, we present evidence that an alternative TCA cycle, in which acetate:succinate CoA-transferase (ASCT) replaces the enzymatic step typically performed by succinyl-CoA synthetase (SCS), has arisen in diverse bacterial groups, including microbial symbionts of animals such as humans and insects.

Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples

NARCIS (Netherlands)

Kester, R.A.; Boer, W. de; Laanbroek, H.J.

1996-01-01

The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of

Short exposure to acetylene to distinguish between nitrifier and denitrifier nitrous oxide production in soil and sediment samples

NARCIS (Netherlands)

Kester, R.A.; De Boer, W.; Laanbroek, H.J.

1996-01-01

The contribution of nitrifiers and denitrifiers to the nitrous oxide production in slurries of calcareous silt loam and river bank sediment at different oxygen concentrations was determined using acetylene as nitrification inhibitor. The addition of 10 Pa acetylene resulted in inhibition of nitrous

Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment

International Nuclear Information System (INIS)

Kampman, Christel; Hendrickx, Tim L.G.; Luesken, Francisca A.; Alen, Theo A. van; Op den Camp, Huub J.M.; Jetten, Mike S.M.; Zeeman, Grietje; Buisman, Cees J.N.; Temmink, Hardy

2012-01-01

Highlights: ► A new concept for low-temperature anaerobic sewage treatment is proposed. ► In this concept, denitrification and methane oxidation are performed by Methylomirabilis oxyfera. ► The bacteria were enriched from fresh water sediment using sequencing fed-batch reactors. ► The volumetric consumption rate has to be increased by an order of magnitude for practical application. ► Further research should focus on systems with improved biomass retention. - Abstract: Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and methane offers the opportunity to develop a reactor in which methane is used as electron donor for denitrification. Such a reactor could be used in a new concept for low-temperature anaerobic sewage treatment, consisting of a UASB-digester system, a reactor for denitrification coupled to anaerobic methane oxidation, and a nitritation reactor. In the present study denitrifying methanotrophic bacteria similar to ‘Candidatus Methylomirabilis oxyfera’ were enriched. Maximum volumetric nitrite consumption rates were 33.5 mg NO 2 − -N/L d (using synthetic medium) and 37.8 mg NO 2 − -N/L d (using medium containing effluent from a sewage treatment plant), which are similar to the maximum rate reported so far. Though the goal was to increase the rates, in both reactors, after reaching these maximum rates, volumetric nitrite consumption rates decreased in time. Results indicate biomass washout may have significantly decelerated enrichment. Therefore, to obtain higher volumetric consumption rates, further research should focus on systems with complete biomass retention.

Phase Preference by Active, Acetate-Utilizing Bacteria at the Rifle, CO Integrated Field Research Challenge Site

International Nuclear Information System (INIS)

Kerkhoff, Lee; Williams, Kenneth H.; Long, Philip E.; McGuinness, L.

2011-01-01

Uranium contaminated groundwaters are a legacy concern for the U.S. Department of Energy. Previous experiments at the Rifle, Colorado Integrated Field Challenge (IFC) site have demonstrated that field-scale addition of acetate to groundwater reduces the ambient soluable uranium concentration, sequestering the radionuclide as uraninite. However, questions remain regarding which microorganism(s) are consuming this acetate and if active groundwater microorganisms are different from active particle-associated bacteria. In this report, 13-C acetate was used to assess the active microbes that synthesize DNA on 3 size fractions (coarse sand, fines (8-approximately 150 micron), groundwater (0.2-8 micron)) over a 24 -day time frame. Results indicated a stronger signal from 13-C acetate associated with the 'fines' fraction compared with smaller amounts of 13-C uptake on the sand fraction and groundwater samples during the SIP incubations. TRFLP analysis of this 13-C-labeled DNA, indicated 31+ 9 OTU's with 6 peaks dominating the active profiles (166, 187, 210, 212, and 277 bp peaks using MnlI). Cloning/sequencing of the amplification products indicated a Geobacter-like group (187, 210, 212 bp) primarily synthesized DNA from acetate in the groundwater phase, an alpha Proteobacterium (166 bp) primarily grew on the fines/sands, and an Acinetobacter sp. (277 bp) utilized much of the 13C acetate in both groundwater and particle-associated phases. These findings will help to delineate the acetate utilization patterns of bacteria during field-scale acetate addition and can lead to improved methods for stimulating distinct microbial populations in situ.

Development of an Acetate- or Sugar-fed Microbial Power Generator for Military Bases

Science.gov (United States)

2012-07-01

8217%/,.")%3"(6.*7,.)ൎ,>*ɞ%0"=%20."* C".G(%$*NMPSNTR* PaQ /PbN>* • 8,0=G6(,*1L@*D$"Ŕś"J"’*?@*1,(J*n_@*_"))6(3*:@*L%JG"#(6F%#,*-L@*D%=)06F6(,*L-@*_;="(F

Development of an Acetate- or Sugar-fed Microbial Power Generator for Military Bases

Science.gov (United States)

2012-07-01

the U.S. military, which consumes 395,000 barrels of oil every day (Warner and Singer, 2009). Transport of fossil fuels to remote places in hostile... sOy ^ % (19%) ****** SP.(6%\\ ’ Soehngenia saccharolytica Geobocter sp. (14%) 11%) ^^ ^ Citrobacter 0</ £ -. sp...performance liquid chromatography (HPLC) equipped with BIORAD Aminex HPX-87H column for sugars and volatile acids analysis. Sucrose analysis employed water

Communities of nirS-type denitrifiers in the water column of the oxygen minimum zone in the eastern South Pacific.

Science.gov (United States)

Castro-González, Maribeb; Braker, Gesche; Farías, Laura; Ulloa, Osvaldo

2005-09-01

The major sites of water column denitrification in the ocean are oxygen minimum zones (OMZ), such as one in the eastern South Pacific (ESP). To understand the structure of denitrifying communities in the OMZ off Chile, denitrifier communities at two sites in the Chilean OMZ (Antofagasta and Iquique) and at different water depths were explored by terminal restriction fragment length polymorphism analysis and cloning of polymerase chain reaction (PCR)-amplified nirS genes. NirS is a functional marker gene for denitrification encoding cytochrome cd1-containing nitrite reductase, which catalyses the reduction of nitrite to nitric oxide, the key step in denitrification. Major differences were found between communities from the two geographic locations. Shifts in community structure occurred along a biogeochemical gradient at Antofagasta. Canonical correspondence analysis indicated that O2, NO3-, NO2- and depth were important environmental factors governing these communities along the biogeochemical gradient in the water column. Phylogenetic analysis grouped the majority of clones from the ESP in distinct clusters of genes from presumably novel and yet uncultivated denitrifers. These nirS clusters were distantly related to those found in the water column of the Arabian Sea but the phylogenetic distance was even higher compared with environmental sequences from marine sediments or any other habitat. This finding suggests similar environmental conditions trigger the development of denitrifiers with related nirS genotypes despite large geographic distances.

Influences of Different Halophyte Vegetation on Soil Microbial Community at Temperate Salt Marsh.

Science.gov (United States)

Chaudhary, Doongar R; Kim, Jinhyun; Kang, Hojeong

2018-04-01

Salt marshes are transitional zone between terrestrial and aquatic ecosystems, occupied mainly by halophytic vegetation which provides numerous ecological services to coastal ecosystem. Halophyte-associated microbial community plays an important role in the adaptation of plants to adverse condition and also affected habitat characteristics. To explore the relationship between halophytes and soil microbial community, we studied the soil enzyme activities, soil microbial community structure, and functional gene abundance in halophytes- (Carex scabrifolia, Phragmites australis, and Suaeda japonica) covered and un-vegetated (mud flat) soils at Suncheon Bay, South Korea. Higher concentrations of total, Gram-positive, Gram-negative, total bacterial, and actinomycetes PLFAs (phospholipid fatty acids) were observed in the soil underneath the halophytes compared with mud flat soil and were highest in Carex soil. Halophyte-covered soils had different microbial community composition due to higher abundance of Gram-negative bacteria than mud flat soil. Similar to PLFA concentrations, the increased activities of β-glucosidase, cellulase, phosphatase, and sulfatase enzymes were observed under halophyte soil compared to mud flat soil and Carex exhibited highest activities. The abundance of archaeal 16S rRNA, fungal ITS, and denitrifying genes (nirK, nirS, and nosZ) were not influenced by the halophytes. Abundance bacterial 16S rRNA and dissimilatory (bi)sulfite (dsrA) genes were highest in Carex-covered soil. The abundance of functional genes involved in methane cycle (mcrA and pmoA) was not affected by the halophytes. However, the ratios of mcrA/pmoA and mcrA/dsrA increased in halophyte-covered soils which indicate higher methanogenesis activities. The finding of the study also suggests that halophytes had increased the microbial and enzyme activities, and played a pivotal role in shaping microbial community structure.

Biogas production from protein-rich biomass: fed-batch anaerobic fermentation of casein and of pig blood and associated changes in microbial community composition.

Directory of Open Access Journals (Sweden)

Etelka Kovács

Full Text Available It is generally accepted as a fact in the biogas technology that protein-rich biomass substrates should be avoided due to inevitable process inhibition. Substrate compositions with a low C/N ratio are considered difficult to handle and may lead to process failure, though protein-rich industrial waste products have outstanding biogas generation potential. This common belief has been challenged by using protein-rich substrates, i.e. casein and precipitated pig blood protein in laboratory scale continuously stirred mesophilic fed-batch biogas fermenters. Both substrates proved suitable for sustained biogas production (0.447 L CH4/g protein oDM, i.e. organic total solids in high yield without any additives, following a period of adaptation of the microbial community. The apparent key limiting factors in the anaerobic degradation of these proteinaceous materials were the accumulation of ammonia and hydrogen sulfide. Changes in time in the composition of the microbiological community were determined by next-generation sequencing-based metagenomic analyses. Characteristic rearrangements of the biogas-producing community upon protein feeding and specific differences due to the individual protein substrates were recognized. The results clearly demonstrate that sustained biogas production is readily achievable, provided the system is well-characterized, understood and controlled. Biogas yields (0.45 L CH4/g oDM significantly exceeding those of the commonly used agricultural substrates (0.25-0.28 L CH4/g oDM were routinely obtained. The results amply reveal that these high-energy-content waste products can be converted to biogas, a renewable energy carrier with flexible uses that can replace fossil natural gas in its applications. Process control, with appropriate acclimation of the microbial community to the unusual substrate, is necessary. Metagenomic analysis of the microbial community by next-generation sequencing allows a precise determination of the

Biogas Production from Protein-Rich Biomass: Fed-Batch Anaerobic Fermentation of Casein and of Pig Blood and Associated Changes in Microbial Community Composition

Science.gov (United States)

Kovács, Etelka; Wirth, Roland; Maróti, Gergely; Bagi, Zoltán; Rákhely, Gábor; Kovács, Kornél L.

2013-01-01

It is generally accepted as a fact in the biogas technology that protein-rich biomass substrates should be avoided due to inevitable process inhibition. Substrate compositions with a low C/N ratio are considered difficult to handle and may lead to process failure, though protein-rich industrial waste products have outstanding biogas generation potential. This common belief has been challenged by using protein-rich substrates, i.e. casein and precipitated pig blood protein in laboratory scale continuously stirred mesophilic fed-batch biogas fermenters. Both substrates proved suitable for sustained biogas production (0.447 L CH4/g protein oDM, i.e. organic total solids) in high yield without any additives, following a period of adaptation of the microbial community. The apparent key limiting factors in the anaerobic degradation of these proteinaceous materials were the accumulation of ammonia and hydrogen sulfide. Changes in time in the composition of the microbiological community were determined by next-generation sequencing-based metagenomic analyses. Characteristic rearrangements of the biogas-producing community upon protein feeding and specific differences due to the individual protein substrates were recognized. The results clearly demonstrate that sustained biogas production is readily achievable, provided the system is well-characterized, understood and controlled. Biogas yields (0.45 L CH4/g oDM) significantly exceeding those of the commonly used agricultural substrates (0.25-0.28 L CH4/g oDM) were routinely obtained. The results amply reveal that these high-energy-content waste products can be converted to biogas, a renewable energy carrier with flexible uses that can replace fossil natural gas in its applications. Process control, with appropriate acclimation of the microbial community to the unusual substrate, is necessary. Metagenomic analysis of the microbial community by next-generation sequencing allows a precise determination of the alterations in

Effects of carbon sources and COD/N ratio on N2O emissions in subsurface flow constructed wetlands.

Science.gov (United States)

Lyu, Wanlin; Huang, Lei; Xiao, Guangquan; Chen, Yucheng

2017-12-01

A set of constructed wetlands under two different carbon sources, namely, glucose (CW) and sodium acetate (YW), was established at a laboratory scale with influent COD/N ratios of 20:1, 10:1, 7:1, 4:1, and 0 to analyze the influence of carbon supply on nitrous oxide emissions. Results showed that the glucose systems generated higher N 2 O emissions than those of the sodium acetate systems. The higher amount of N 2 O-releasing fluxes in the CWs than in the YWs was consistent with the higher NO 2 - -N accumulation in the former than in the latter. Moreover, electron competition was tighter in the CWs and contributed to the incomplete denitrification with poor N 2 O production performance. Illumina MiSeq sequencing demonstrated that some denitrifying bacteria, such as Denitratisoma, Bacillus, and Zoogloea, were higher in the YWs than in the CWs. This result indicated that the carbon source is important in controlling N 2 O emissions in microbial communities. Copyright © 2017. Published by Elsevier Ltd.

Characterization of microbial communities in deep groundwater from granitic rock

International Nuclear Information System (INIS)

Jain, D.K.; Stroes-Gascoyne, S.; Providenti, M.; Tanner, C.; Cord, I.

1997-01-01

The microbial characteristics of deep granitic nutrient-poor groundwater from two boreholes at the Underground Research Laboratory of Atomic Energy of Canada Limited were studied. Scanning electron microscopy of the groundwater samples revealed significant numbers of bacteria of various sizes and shapes, including spherical, rod, and curved shaped. A few bacteria with appendages were also observed. Significant numbers of bacteria (∼l0 5 /mL) were enumerated using acridine orange (AO) staining. An active microbial population was detected with three direct methods and it ranged from 1 to 83% of the AO count, depending on the method used. Culturable aerobic and anaerobic (including facultative) heterotrophic bacteria ranged from 0.06 to 10.2% and 0.008 to 7.35%, respectively, of the AO count. Denitrifying. N 2 - fixing, sulphate-reducing, and iron-precipitating bacteria were present, but no iron-oxidizing bacteria or methanogens could be detected. Tentative identification of 160 isolates using the Biolog system showed a predominance of three Pseudomonas species, P. fluorescens, P. marginalis, and P. corrugata. Phospholipid fatty acid analysis showed that the bacteria in the groundwater samples faced starvation stress. However, laboratory studies showed that these bacteria can efficiently uptake and mineralize organic substrates when supplied. (author)

Biostimulation induces syntrophic interactions that impact C, S and N cycling in a sediment microbial community

Energy Technology Data Exchange (ETDEWEB)

Handley, KM [University of California, Berkeley; Verberkmoes, Nathan C [ORNL; Steefel, Carl I [Lawrence Berkeley National Laboratory (LBNL); Sharon, I [University of California, Berkeley; Williams, Ken [Lawrence Berkeley National Laboratory (LBNL); Miller, CS [University of California, Berkeley; Frischkorn, Kyle C [University of California, Berkeley; Chourey, Karuna [ORNL; Thomas, Brian [University of California, Berkeley; Shah, Manesh B [ORNL; Long, Phil [Pacific Northwest National Laboratory (PNNL); Hettich, Robert {Bob} L [ORNL; Banfield, Jillian F. [University of California, Berkeley

2013-01-01

Stimulation of subsurface microorganisms to induce reductive immobilization of metals is a promising approach for bioremediation, yet the overall microbial community response is typically poorly understood. Here we used community proteogenomics to test the hypothesis that excess input of acetate activates syntrophic interactions among autotrophs and heterotrophs. A flow-through sediment column was incubated in a groundwater well of an acetate-amended aquifer. Genomic sequences from the community recovered during microbial sulfate reduction were used to econstruct, de novo, near-complete genomes for Desulfobacter (Deltaproteobacteria) and relatives of Sulfurovum and Sulfurimonas (Epsilonproteobacteria), and Bacteroidetes. Partial genomes were obtained for Clostridiales (Firmicutes) and Desulfuromonadales-like Deltaproteobacteria. The majority of proteins identified by mass spectrometry corresponded to Desulfobacter-like species, and demonstrate the role of this organism in sulfate reduction (Dsr and APS), nitrogen-fixation (Nif) and acetate oxidation to CO2 during amendment. Results suggest less abundant Desulfuromonadales and Bacteroidetes also actively contributed to CO2 production via the TCA cycle. Proteomic data indicate that sulfide was partially re-oxidized by Epsilonproteobacteria through nitrate-dependent sulfide oxidation (using Nap, Nir, Nos, SQR and Sox), with CO2 fixed using the reverse TCA cycle. Modeling shows that this reaction was thermodynamically possible, and kinetically favorable relative to acetate-dependent denitrification. We conclude that high-levels of carbon amendment aimed to stimulate anaerobic heterotrophy led to carbon fixation in co-dependent chemoautotrophs. These results have implications for understanding complex ecosystem behavior, and show that high levels of organic carbon supplementation can expand the range of microbial functionalities accessible for ecosystem manipulation.

Microbial Reverse Electrodialysis Cells for Synergistically Enhanced Power Production

KAUST Repository

Kim, Younggy

2011-07-01

A new type of bioelectrochemical system for producing electrical power, called a microbial reverse-electrodialysis cell (MRC), was developed to increase voltages and power densities compared to those generated individually by microbial fuel cells (MFCs) or reverse electrodialysis (RED) systems. In RED systems, electrode overpotentials create significant energy losses due to thermodynamically unfavorable electrode reactions, and therefore a large number of stacked cells must be used to have significant energy recovery. This results in high capital costs for the large number of membranes, and increases energy losses from pumping water through a large number of cells. In an MRC, high overpotentials are avoided through oxidation of organic matter by exoelectrogenic bacteria on the anode and oxygen reduction on the cathode. An MRC containing only five pairs of RED cells, fed solutions typical of seawater (600 mM NaCl) and river water (12 mM NaCl) at 0.85 mL/min, produced up to 3.6 W/m2 (cathode surface area) and 1.2-1.3 V with acetate as a substrate. Pumping accounted for <2% of the produced power. A higher flow rate (1.55 mL/min) increased power densities up to 4.3 W/m2. COD removal was 98% with a Coulombic efficiency of 64%. Power production by the individual components was substantially lower with 0.7 W/m2 without salinity driven energy, and <0.015 W/m2 with reduced exoelectrogenic activity due to substrate depletion. These results show that the combination of an MFC and a RED stack synergistically increases performance relative to the individual systems, producing a new type of system that can be used to more efficiently capture salinity driven energy from seawater and river water. © 2011 American Chemical Society.

Effects of forage source and forage particle size as a free-choice provision on growth performance, rumen fermentation, and behavior of dairy calves fed texturized starters.

Science.gov (United States)

Omidi-Mirzaei, H; Azarfar, A; Mirzaei, M; Kiani, A; Ghaffari, M H

2018-05-01

We investigated the interactive effects of forage source and forage particle size (PS) as a free-choice provision on growth performance, rumen fermentation, and behavior of dairy calves fed texturized starters. Forty-eight Holstein calves (42 ± 3 kg of body weight) were randomly assigned (n = 12 calves per treatment) in a 2 × 2 factorial arrangement of treatments with the factors of forage source [alfalfa hay (AH) and wheat straw (WS)] and forage PS [(AH: medium = 1.96 mm or long = 3.93 mm) and (WS: medium = 2.03 mm or long = 4.10 mm), as geometric mean diameters]. The treatments were (1) AH with medium PS (AH-MPS), (2) AH with long PS (AH-LPS), (3) WS with medium PS (WS-MPS), and (4) WS with long PS (WS-LPS). Regardless of forage PS, the preweaning starter intake, dry matter intake, metabolizable energy intake, weaning body weight, and forage intake were greater for AH calves than WS calves. Average daily gain, average daily gain/metabolizable energy intake, feed efficiency, and final body weight of the calves did not differ among groups. An interaction of forage source and forage PS influenced acetate, propionate, and acetate-to-propionate ratio in the rumen on d 35, with the greatest acetate proportion and acetate-to-propionate ratio, but the least propionate proportion for AH-MPS calves than the other calves. The total volatile fatty acid concentration and the rumen proportions of propionate (d 70), butyrate (d 35), and valerate (d 35) were greater in AH-MPS calves than in AH-LPS calves. Calves fed AH had greater total volatile fatty acid concentration (d 35 and 70) and propionate proportion (d 70), but lesser ruminal proportions of butyrate (d 35 and 70), valerate (d 35 and 70), and acetate-to-propionate ratio (d 70) compared with calves fed WS. The ruminal valerate proportion (d 70) was greatest in WS-MPS calves than the other calves. An interaction of forage source and forage PS influenced preweaning standing time and starter eating time, with the least

Biological activity of the non-microbial fraction of kefir: antagonism against intestinal pathogens.

Science.gov (United States)

Iraporda, Carolina; Abatemarco Júnior, Mário; Neumann, Elisabeth; Nunes, Álvaro Cantini; Nicoli, Jacques R; Abraham, Analía G; Garrote, Graciela L

2017-08-01

Kefir is a fermented milk obtained by the activity of kefir grains which are composed of lactic and acetic acid bacteria, and yeasts. Many beneficial health effects have been associated with kefir consumption such as stimulation of the immune system and inhibition of pathogenic microorganisms. The biological activity of kefir may be attributed to the presence of a complex microbiota as well as the microbial metabolites that are released during fermentation. The aim of this work was to characterise the non-microbial fraction of kefir and to study its antagonism against Escherichia coli, Salmonella spp. and Bacillus cereus. During milk fermentation there was a production of organic acids, mainly lactic and acetic acid, with a consequent decrease in pH and lactose content. The non-microbial fraction of kefir added to nutrient broth at concentrations above 75% v/v induced a complete inhibition of pathogenic growth that could be ascribed to the presence of un-dissociated lactic acid. In vitro assays using an intestinal epithelial cell model indicated that pre-incubation of cells with the non-microbial fraction of kefir did not modify the association/invasion of Salmonella whereas pre-incubation of Salmonella with this fraction under conditions that did not affect their viability significantly decreased the pathogen's ability to invade epithelial cells. Lactate exerted a protective effect against Salmonella in a mouse model, demonstrating the relevance of metabolites present in the non-microbial fraction of kefir produced during milk fermentation.

A doubling of microphytobenthos biomass coincides with a tenfold increase in denitrifier and total bacterial abundances in intertidal sediments of a temperate estuary.

Directory of Open Access Journals (Sweden)

Helen Decleyre

Full Text Available Surface sediments are important systems for the removal of anthropogenically derived inorganic nitrogen in estuaries. They are often characterized by the presence of a microphytobenthos (MPB biofilm, which can impact bacterial communities in underlying sediments for example by secretion of extracellular polymeric substances (EPS and competition for nutrients (including nitrogen. Pyrosequencing and qPCR was performed on two intertidal surface sediments of the Westerschelde estuary characterized by a two-fold difference in MPB biomass but no difference in MPB composition. Doubling of MPB biomass was accompanied by a disproportionately (ten-fold increase in total bacterial abundances while, unexpectedly, no difference in general community structure was observed, despite significantly lower bacterial richness and distinct community membership, mostly for non-abundant taxa. Denitrifier abundances corresponded likewise while community structure, both for nirS and nirK denitrifiers, remained unchanged, suggesting that competition with diatoms for nitrate is negligible at concentrations in the investigated sediments (appr. 1 mg/l NO3-. This study indicates that MPB biomass increase has a general, significantly positive effect on total bacterial and denitrifier abundances, with stimulation or inhibition of specific bacterial groups that however do not result in a re-structured community.

Microbial reverse-electrodialysis chemical-production cell for acid and alkali production

KAUST Repository

Zhu, Xiuping

2013-06-01

A new type of bioelectrochemical system, called a microbial reverse-electrodialysis chemical-production cell (MRCC), was developed to produce acid and alkali using energy derived from organic matter (acetate) and salinity gradients (NaCl solutions representative of seawater and river water). A bipolar membrane (BPM) was placed next to the anode to prevent Cl- contamination and acidification of the anolyte, and to produce protons for HCl recovery. A 5-cell paired reverse-electrodialysis (RED) stack provided the electrical energy required to overcome the BPM over-potential (0.3-0.6 V), making the overall process spontaneous. The MRCC reactor produced electricity (908 mW/m2) as well as concentrated acidic and alkaline solutions, and therefore did not require an external power supply. After a fed-batch cycle, the pHs of the chemical product solutions were 1.65 ± 0.04 and 11.98 ± 0.10, due to the production of 1.35 ± 0.13 mmol of acid, and 0.59 ± 0.14 mmol of alkali. The acid- and alkali-production efficiencies based on generated current were 58 ± 3% and 25 ± 3%. These results demonstrated proof-of-concept acid and alkali production using only renewable energy sources. © 2013 Elsevier B.V.

Microbial fuel cell: A green technology

International Nuclear Information System (INIS)

Jong Bor Chyan; Liew Pauline Woan Ying; Muhamad Lebai Juri; Ahmad Zainuri Mohd Dzomir; Leo Kwee Wah; Mat Rasol Awang

2010-01-01

Microbial Fuel Cell (MFC) was developed which was able to generate bio energy continuously while consuming wastewater containing organic matters. Even though the bio energy generated is not as high as hydrogen fuel cell, the MFC demonstrated great potential in bio-treating wastewater while using it as fuel source. Thus far, the dual-ability of the MFC to generate bio energy and bio-treating organic wastewater has been examined successfully using synthetic acetate and POME wastewaters. (author)

Draft genome sequence of Bacillus azotoformans MEV2011, a (Co-) denitrifying strain unable to grow with oxygen.

Science.gov (United States)

Nielsen, Maja; Schreiber, Lars; Finster, Kai; Schramm, Andreas

2015-01-01

Bacillus azotoformans MEV2011, isolated from soil, is a microaerotolerant obligate denitrifier, which can also produce N2 by co-denitrification. Oxygen is consumed but not growth-supportive. The draft genome has a size of 4.7 Mb and contains key genes for both denitrification and dissimilatory nitrate reduction to ammonium.

Fluctuation of microbial activities after influent load variations in a full-scale SBR. Recovery of the biomass after starvation

Energy Technology Data Exchange (ETDEWEB)

Cabezas, Angela; Draper, Patricia; Etchebehere, Claudia [Universidad de la Republica, Montevideo (Uruguay). Catedra de Microbiologia, Facultad de Quimica y Facultad de Ciencias

2009-10-15

Due to variations in the production levels, a full-scale sequencing batch reactor (SBR) for post-treatment of tannery wastewater was exposed to low and high ammonia load periods. In order to study how these changes affected the N-removal capacity, the microbiology of the reactor was studied by a diverse set of techniques including molecular tools, activity tests, and microbial counts in samples taken along 3 years. The recover capacity of the biomass was also studied in a lab-scale reactor operated with intermittent aeration without feeding for 36 days. The results showed that changes in the feeding negatively affected the nitrifying community, but the nitrogen removal efficiencies could be restored after the concentration stress. Species substitution was observed within the nitrifying bacteria, Nitrosomonas europaea and Nitrobacter predominated initially, and after an ammonia overload period, Nitrosomonas nitrosa and Nitrospira became dominant. Some denitrifiers, with nirS related to Alicycliphilus, Azospirillum, and Marinobacter nirS, persisted during long-term reactor operation, but the community fluctuated both in composition and in abundance. This fluctuating community may better resist the continuous changes in the feeding regime. Our results showed that a nitrifying-denitrifying SBR could be operated with low loads or even without feeding during production shut down periods. (orig.)

Performance and membrane fouling of a step-fed submerged membrane sequencing batch reactor treating swine biogas digestion slurry.

Science.gov (United States)

Han, Zhiying; Chen, Shixia; Lin, Xiaochang; Yu, Hongjun; Duan, Li'an; Ye, Zhangying; Jia, Yanbo; Zhu, Songming; Liu, Dezhao

2018-01-02

To identify the performance of step-fed submerged membrane sequencing batch reactor (SMSBR) treating swine biogas digestion slurry and to explore the correlation between microbial metabolites and membrane fouling within this novel reactor, a lab-scale step-fed SMSBR was operated under nitrogen loading rate of 0.026, 0.052 and 0.062 g NH 4 + -N (gVSS·d) -1 . Results show that the total removal efficiencies for NH 4 + -N, total nitrogen and chemical oxygen demand in the reactor (>94%, >89% and >97%, respectively) were high during the whole experiment. However, the cycle removal efficiency of NH 4 + -N decreased significantly when the nitrogen loading rate was increased to 0.062 g NH 4 + -N (gVSS·d) -1 . The total removal efficiency of total phosphorus in the step-fed SMSBR was generally higher than 75%, though large fluctuations were observed during the experiments. In addition, the concentrations of microbial metabolites, i.e., soluble microbial products (SMP) and extracellular polymeric substances (EPS) from activated sludge increased as nitrogen loading rate increased, both showing quadratic equation correlations with viscosity of the mixed liquid in the step-fed SMSBR (both R 2 > 0.90). EPS content was higher than SMP content, while protein (PN) was detected as the main component in both SMP and EPS. EPS PN was found to be well correlated with transmembrane pressure, membrane flux and the total membrane fouling resistance. Furthermore, the three-dimensional excitation-emission matrix fluorescence spectroscopy results suggested the tryptophan-like protein as one of the main contributors to the membrane fouling. Overall, this study showed that the step-fed SMSBR could be used to treat swine digestion slurry at nitrogen loading rate of 0.052 g NH 4 + -N (gVSS·d) -1 , and the control strategy of membrane fouling should be developed based on reducing the tryptophan-like PN in EPS.

Final Technical Report: DOE-Biological Ocean Margins Program. Microbial Ecology of Denitrifying Bacteria in the Coastal Ocean.

Energy Technology Data Exchange (ETDEWEB)

Lee Kerkhof

2013-01-01

The focus of our research was to provide a comprehensive study of the bacterioplankton populations off the coast of New Jersey near the Rutgers University marine field station using terminal restriction fragment polymorphism analysis (TRFLP) coupled to 16S rRNA genes for large data set studies. Our three revised objectives to this study became: (1) to describe bacterioplankton population dynamics in the Mid Atlantic Bight using TRFLP analysis of 16S rRNA genes. (2) to determine whether spatial and temporal factors are driving bacterioplankton community dynamics in the MAB using monthly samping along our transect line over a 2-year period. (3) to identify dominant members of a coastal bacterioplankton population by clonal library analysis of 16S rDNA genes and sequencing of PCR product corresponding to specific TRFLP peaks in the data set. Although open ocean time-series sites have been areas of microbial research for years, relatively little was known about the population dynamics of bacterioplankton communities in the coastal ocean on kilometer spatial and seasonal temporal scales. To gain a better understanding of microbial community variability, monthly samples of bacterial biomass were collected in 1995-1996 along a 34-km transect near the Long-Term Ecosystem Observatory (LEO-15) off the New Jersey coast. Surface and bottom sampling was performed at seven stations along a transect line with depths ranging from 1 to 35m (n=178). The data revealed distinct temporal patterns among the bacterioplankton communities in the Mid-Atlantic Bight rather than grouping by sample location or depth (figure 2-next page). Principal components analysis models supported the temporal patterns. In addition, partial least squares regression modeling could not discern a significant correlation from traditional oceanographic physical and phytoplankton nutrient parameters on overall bacterial community variability patterns at LEO-15. These results suggest factors not traditionally

Impact of nitrogen feeding regulation on polyhydroxyalkanoates production by mixed microbial cultures.

Science.gov (United States)

Silva, Fernando; Campanari, Sabrina; Matteo, Stefania; Valentino, Francesco; Majone, Mauro; Villano, Marianna

2017-07-25

A sequencing batch reactor (SBR) is typically used for selecting mixed microbial cultures (MMC) for polyhydroxyalkanoate (PHA) production. Since many waste streams suitable as process feedstock for PHA production are nitrogen-deficient, a nutrient supply in the SBR is typically required to allow for efficient microbial growth. The scope of this study was to devise a nitrogen feeding strategy which allows controlling the nitrogen levels during the feast and famine regime of a lab-scale SBR, thereby selecting for PHA-storing microorganisms. At the beginning of the cycle the reactor was fed with a synthetic mixture of acetic and propionic acids at an overall organic load rate of 8.5gCODL -1 d -1 (i.e. 260CmmolL -1 d -1 ), whereas nitrogen (in the form of ammonium sulphate) was added either simultaneously to the carbon feed (coupled feeding strategy) or after the end of the feast phase (uncoupled feeding strategy). As a main result, PHA production was more than doubled (up to about 1300±64mgCODL -1 ) when carbon and nitrogen were separately fed and the higher PHA production also corresponded to an 82% increase in the polymer HV content (up to 20±1%, wtwt -1 ). Three SBR runs were performed with the uncoupled carbon and nitrogen feeding at different carbon to nitrogen (C/N) ratios (of 14.3, 17.9, and 22.3CmolNmol -1 , respectively) which were varied by progressively reducing the concentration of the nitrogen feeding. In spite of a comparable PHA storage yield at 14.3 and 17.9CmolNmol -1 (0.41±0.05 gCOD PHA gCOD VFA -1 and 0.38±0.05 gCOD PHA gCOD VFA -1 , respectively), the storage response of the selected MMC significantly decreased when the C/N ratio was set at the highest investigated value. Notably, an increase in this parameter also resulted in a change in the HV content in the polymer regardless the composition of the organic acids solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Sampling natural biofilms: a new route to build efficient microbial anodes.

Science.gov (United States)

Erable, Benjamin; Roncato, Marie-Anne; Achouak, Wafa; Bergel, Alain

2009-05-01

Electrochemically active biofilms were constructed on graphite anodes under constant polarization at -0.1V vs saturated calomel reference (SCE) with 10 mM acetate as substrate. The reactors were inoculated with three different microbial samples that were drawn from exactly the same place in a French Atlantic coastal port (i) by scraping the biofilm that had formed naturally on the surface of a floating bridge, (ii) by taking marine sediments just under the floating bridge, and (iii) by taking nearby beach sand. Current densities of 2.0 A/m2 were reached using the biofilm sample as inoculum while only 0.4 A/m2 and 0.8 A/m2 were obtained using the underlying sediments and the beach sand, respectively. The structure of bacterial communities forming biofilms was characterized by denaturing gradient gel electrophoresis (DGGE) analysis, and revealed differences between samples with the increase in relative intensities of some bands and the appearance of others. Bacteria close related to Bacteroidetes, Halomonas, and Marinobacterium were retrieved only from the efficient EA-biofilms formed from natural biofilms, whereas, bacteria close related to Mesoflavibacter were predominant on biofilm formed from sediments. The marine biofilm was selected as the inoculum to further optimize the microbial anode. Epifluorescence microscopy and SEM confirmed that maintaining the electrode under constant polarization promoted rapid settlement of the electrode surface by a bacterial monolayer film. The microbial anode was progressively adapted to the consumption of acetate by three serial additions of substrate, thus improving the Coulombic efficiency of acetate consumption from 31 to 89%. The possible oxidation of sulfide played only a very small part in the current production and the biofilm was not able to oxidize hydrogen. Graphite proved to be more efficient than dimensionally stable anode (DSA) or stainless steel butthis result might be due to differences in the surface roughness

Calibration and analysis of genome-based models for microbial ecology.

Science.gov (United States)

Louca, Stilianos; Doebeli, Michael

2015-10-16

Microbial ecosystem modeling is complicated by the large number of unknown parameters and the lack of appropriate calibration tools. Here we present a novel computational framework for modeling microbial ecosystems, which combines genome-based model construction with statistical analysis and calibration to experimental data. Using this framework, we examined the dynamics of a community of Escherichia coli strains that emerged in laboratory evolution experiments, during which an ancestral strain diversified into two coexisting ecotypes. We constructed a microbial community model comprising the ancestral and the evolved strains, which we calibrated using separate monoculture experiments. Simulations reproduced the successional dynamics in the evolution experiments, and pathway activation patterns observed in microarray transcript profiles. Our approach yielded detailed insights into the metabolic processes that drove bacterial diversification, involving acetate cross-feeding and competition for organic carbon and oxygen. Our framework provides a missing link towards a data-driven mechanistic microbial ecology.

Protective Effects of Vitamin C (Ascorbic Acid in Lead Acetate Exposed Diabetic Male Rats: Evaluation of Blood Biochemical Parameters and Testicular Histopathology

Directory of Open Access Journals (Sweden)

Alireza AYOUBI

2015-01-01

Full Text Available The aim of this study was to investigate the protective effects of vitamin C against lead toxicity by measuring the blood parameters and studying histopathology of testis in diabetic male rats. Wister rats (42 were randomly assigned into7 groups: I healthy; II fed lead acetate only; III vitamin C administered only; IV diabetic; V diabetic rats administered by vitamin C; VI diabetic rats given lead acetate and VII diabetic rats received lead acetate and vitamin C. The diabetic and lead groups had higher glucose, cholesterol, LDL, triglycerides and lower insulin and HDL concentration than the control group. It was found that vitamin C administration led to a lower level of blood glucose, cholesterol, LDL and triglycerides and higher HDL concentration in diabetic rats significantly. It was concluded that the antioxidant property of vitamin C resulted in reducing the oxidative stress complications of toxic levels of lead acetate in diabetic rats.

Effects of dietary inclusion of palm kernel cake on nutrient utilization, rumen fermentation characteristics and microbial populations of goats fed Paspalum plicatulum hay-based diet

Directory of Open Access Journals (Sweden)

Sahutaya Pongprayoon

2010-12-01

Full Text Available To investigate the effects of inclusion of palm kernel cake (PKC in the diets on intake, digestibility, rumen fermentationcharacteristics, nitrogen balance and microbial N supply, five goats (initial BW = 20±1 kg were randomly assigned to a55 Latin square design to receive five diets, T1 = concentrate with 15% PKC, T2 = 25% PKC, T3 = 35% PKC, T4 = 45% PKCand T5 = 55% PKC, of dietary dry matter, respectively. Plicatulum hay was offered ad libitum as the roughage. A metabolismtrial lasted for 21 days during which live weight changes and feed intakes were measured. Based on this experiment, therewere no significant differences (p>0.05 among treatment groups regarding dry matter (DM intake and digestion coefficientsof DM, organic matter, crude protein, neutral detergent fiber and acid detergent fiber, except in T4 and T5 (45 and 55% PKCwhich had lower (p0.05, however the concentration of total volatile fatty acids and protozoal populations were slightly lower forgoats fed inclusion of 45-55% PKC as compared with other treatments. Based on this experiment, it could be concluded thatthe optimal level of PKC in concentrate should be 15-35% for goats fed with plicatulum hay and that it may be an effectivemeans of exploiting the use of local feed resources for goat production.

Simulation of Feedforward-Feedback Control of Dissolved Oxygen of Microbial Repeated Fed-batch Culture

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Ling Gao

2016-09-01

Full Text Available Fed-batch culture is often used in industry, and dissolved oxygen (DO concentration control is important in fermentation process control. DO control is often applied by using feedback (FB control strategy. But, feedforward-feedback (FF-FB control has the advantage in dealing with the time-varying characteristics resulted from the cell growth during the fermentation process. Mathematical modeling and computer simulation is a useful tool in analysis of the control system.  In this research, the FF-FB DO control and FB substrate control of repeated fed-batch culture process is modeled and simulated. The results showed the feasibility of the control strategy. These results are useful for control system development and process analyses and optimization.

Microbial aspects of synthesis gas fed bioreactors treating sulfate and metal rich wastewaters

NARCIS (Netherlands)

Houten, van B.H.G.W.

2006-01-01

The use of synthesis gas fed sulfate-reducing bioreactors to simultaneously remove both oxidized sulfur compounds and metals shows great potential to treat wastewaters generated as a result of flue gas scrubbing, mining activities and galvanic processes. Detailed information about the phylogenetic

Enrichment of denitrifying methanotrophic bacteria for application after direct low-temperature anaerobic sewage treatment

Energy Technology Data Exchange (ETDEWEB)

Kampman, Christel, E-mail: christel.kampman@wur.nl [Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen (Netherlands); Hendrickx, Tim L.G. [Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen (Netherlands); Luesken, Francisca A.; Alen, Theo A. van; Op den Camp, Huub J.M.; Jetten, Mike S.M. [Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Zeeman, Grietje; Buisman, Cees J.N.; Temmink, Hardy [Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA, Wageningen (Netherlands)

2012-08-15

Highlights: Black-Right-Pointing-Pointer A new concept for low-temperature anaerobic sewage treatment is proposed. Black-Right-Pointing-Pointer In this concept, denitrification and methane oxidation are performed by Methylomirabilis oxyfera. Black-Right-Pointing-Pointer The bacteria were enriched from fresh water sediment using sequencing fed-batch reactors. Black-Right-Pointing-Pointer The volumetric consumption rate has to be increased by an order of magnitude for practical application. Black-Right-Pointing-Pointer Further research should focus on systems with improved biomass retention. - Abstract: Despite many advantages of anaerobic sewage treatment over conventional activated sludge treatment, it has not yet been applied in temperate zones. This is especially because effluent from low-temperature anaerobic treatment contains nitrogen and dissolved methane. The presence of nitrogen and methane offers the opportunity to develop a reactor in which methane is used as electron donor for denitrification. Such a reactor could be used in a new concept for low-temperature anaerobic sewage treatment, consisting of a UASB-digester system, a reactor for denitrification coupled to anaerobic methane oxidation, and a nitritation reactor. In the present study denitrifying methanotrophic bacteria similar to 'Candidatus Methylomirabilis oxyfera' were enriched. Maximum volumetric nitrite consumption rates were 33.5 mg NO{sub 2}{sup -}-N/L d (using synthetic medium) and 37.8 mg NO{sub 2}{sup -}-N/L d (using medium containing effluent from a sewage treatment plant), which are similar to the maximum rate reported so far. Though the goal was to increase the rates, in both reactors, after reaching these maximum rates, volumetric nitrite consumption rates decreased in time. Results indicate biomass washout may have significantly decelerated enrichment. Therefore, to obtain higher volumetric consumption rates, further research should focus on systems with complete biomass

Enhancement of electricity production by graphene oxide in soil microbial fuel cells and plant microbial fuel cells

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Yuko eGoto

2015-04-01

Full Text Available The effects of graphene oxide (GO on electricity generation in soil microbial fuel cells (SMFCs and plant microbial fuel cell (PMFCs were investigated. GO at concentrations ranging from 0 to 1.9 g•kg-1 was added to soil and reduced for 10 days under anaerobic incubation. All SMFCs (GO-SMFCs utilizing the soils incubated with GO produced electricity at a greater rate and in higher quantities than the SMFCs which did not contain GO. In fed-batch operations, the overall average electricity generation in GO-SMFCs containing 1.0 g•kg-1 of GO was 40 ± 19 mW•m-2, which was significantly higher than the value of 6.6 ± 8.9 mW•m-2 generated from GO-free SMFCs (p -2 of electricity after 27 days of operation. Collectively, this study demonstrates that GO added to soil can be microbially reduced in soil, and facilitates electron transfer to the anode in both SMFCs and PMFCs.

Effects of feeding layer faeces on performance and microbial ...

African Journals Online (AJOL)

Thirty-two (32) weaned rabbits of mixed breeds and sexes with mean weight (410 g) were randomly allocated to four dietary treatments at 0, 10, 20 and 30% in a completely randomized design experiment to evaluate the growth performance and microbial diversity in the faeces of rabbits fed dietary inclusion of layers faeces.

Two-stage pretreatment of excess sludge for electricity generation in microbial fuel cell.

Science.gov (United States)

Zhang, Yi; Zhao, Yang-Guo; Guo, Liang; Gao, Mengchun

2018-01-12

Thermophiles hydrolysis and acidogens fermentation were sequentially adopted to pretreat excess sludge for microbial fuel cell (MFC) electricity production. The results indicated that MFC fed with the thermophiles-acidogens pretreated sludge (MFC AB), reached a higher removal of ammonia nitrogen than the MFC fed with the heating hydrolysis and acidogens fermentation pretreated sludge (MFC NB). However, compared with the MFC AB, MFC NB presented a better performance for removal of soluble chemical oxygen demand (SCOD) (90.08%) and protein (82.42%). As for the electricity production, MFC NB obtained higher voltage of 0.632 V and maximum power density with 1.05 W/m 3 while MFC AB reached maximum voltage of 0.373 V and maximum power density of 0.58 W/m 3 . Bacterial 16S rRNA-based molecular microbial techniques showed that microbial communities on both MFC anode biofilms was diverse and different. The cooperation of fermentation bacteria and electricigen Shewanella baltica in the MFC NB may have contributed towards the improvement of electricity generation.

Drug-loaded Cellulose Acetate and Cellulose Acetate Butyrate Films ...

African Journals Online (AJOL)

The purpose of this research work was to evaluate the contribution of formulation variables on release properties of matrix type ocular films containing chloramphenicol as a model drug. This study investigated the use of cellulose acetate and cellulose acetate butyrate as film-forming agents in development of ocular films.

Microchemostat - microbial continuous culture in a polymer-based, instrumented microbioreactor

DEFF Research Database (Denmark)

Zhang, Z.; Bocazzi, P.; Choi, H. G.

2006-01-01

-based microbioreactor system integrated with optical density (OD), pH, and dissolved oxygen (DO) real-time measurements for continuous cultivation of microbial cells. Escherichia coli (E. coli) cells are continuously cultured in a 150 mL, membrane-aerated, well-mixed microbioreactor fed by a pressure-driven flow......In a chemostat, microbial cells reach a steady state condition at which cell biomass production, substrates and the product concentrations remain constant. These features make continuous culture a unique and powerful tool for biological and physiological research. We present a polymer...

Syntrophic acetate oxidation in two-phase (acid-methane) anaerobic digesters.

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Shimada, T; Morgenroth, E; Tandukar, M; Pavlostathis, S G; Smith, A; Raskin, L; Kilian, R E

2011-01-01

The microbial processes involved in two-phase anaerobic digestion were investigated by operating a laboratory-scale acid-phase (AP) reactor and analyzing two full-scale, two-phase anaerobic digesters operated under mesophilic (35 °C) conditions. The digesters received a blend of primary sludge and waste activated sludge (WAS). Methane levels of 20% in the laboratory-scale reactor indicated the presence of methanogenic activity in the AP. A phylogenetic analysis of an archaeal 16S rRNA gene clone library of one of the full-scale AP digesters showed that 82% and 5% of the clones were affiliated with the orders Methanobacteriales and Methanosarcinales, respectively. These results indicate that substantial levels of aceticlastic methanogens (order Methanosarcinales) were not maintained at the low solids retention times and acidic conditions (pH 5.2-5.5) of the AP, and that methanogenesis was carried out by hydrogen-utilizing methanogens of the order Methanobacteriales. Approximately 43, 31, and 9% of the archaeal clones from the methanogenic phase (MP) digester were affiliated with the orders Methanosarcinales, Methanomicrobiales, and Methanobacteriales, respectively. A phylogenetic analysis of a bacterial 16S rRNA gene clone library suggested the presence of acetate-oxidizing bacteria (close relatives of Thermacetogenium phaeum, 'Syntrophaceticus schinkii,' and Clostridium ultunense). The high abundance of hydrogen consuming methanogens and the presence of known acetate-oxidizing bacteria suggest that acetate utilization by acetate oxidizing bacteria in syntrophic interaction with hydrogen-utilizing methanogens was an important pathway in the second-stage of the two-phase digestion, which was operated at high ammonium-N concentrations (1.0 and 1.4 g/L). A modified version of the IWA Anaerobic Digestion Model No. 1 (ADM1) with extensions for syntrophic acetate oxidation and weak-acid inhibition adequately described the dynamic profiles of volatile acid production

Effects of cell wall degrading enzymes on carbohydrate fractions and metabolites in stomach and ileum of pigs fed wheat bran based diets

NARCIS (Netherlands)

Meulen, van der J.; Inborr, J.; Bakker, J.G.M.

2001-01-01

Pigs were fed diets containing 40 heat bran incubated with a water:acetic acid mixture (control, C) and a cellulase (Cel-i) or xylanase (Xyl-i) preparation or with addition of the cellulase (Cel-a) or xylanase (Xyl-a) preparation immediately before feeding. Stomach and ileal samples were analysed

Abundance and diversity of bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants revealed by high-throughput sequencing.

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Zhu Wang

Full Text Available Biological nitrification/denitrification is frequently used to remove nitrogen from tannery wastewater containing high concentrations of ammonia. However, information is limited about the bacterial nitrifiers and denitrifiers and their functional genes in tannery wastewater treatment plants (WWTPs due to the low-throughput of the previously used methods. In this study, 454 pyrosequencing and Illumina high-throughput sequencing, combined with molecular methods, were used to comprehensively characterize structures and functions of nitrification and denitrification bacterial communities in aerobic and anaerobic sludge of two full-scale tannery WWTPs. Pyrosequencing of 16S rRNA genes showed that Proteobacteria and Synergistetes dominated in the aerobic and anaerobic sludge, respectively. Ammonia-oxidizing bacteria (AOB amoA gene cloning revealed that Nitrosomonas europaea dominated the ammonia-oxidizing community in the WWTPs. Metagenomic analysis showed that the denitrifiers mainly included the genera of Thauera, Paracoccus, Hyphomicrobium, Comamonas and Azoarcus, which may greatly contribute to the nitrogen removal in the two WWTPs. It is interesting that AOB and ammonia-oxidizing archaea had low abundance although both WWTPs demonstrated high ammonium removal efficiency. Good correlation between the qPCR and metagenomic analysis is observed for the quantification of functional genes amoA, nirK, nirS and nosZ, indicating that the metagenomic approach may be a promising method used to comprehensively investigate the abundance of functional genes of nitrifiers and denitrifiers in the environment.

Strategies for Reducing the Start-up Operation of Microbial Electrochemical Treatments of Urban Wastewater

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Zulema Borjas

2015-12-01

Full Text Available Microbial electrochemical technologies (METs constitute the core of a number of emerging technologies with a high potential for treating urban wastewater due to a fascinating reaction mechanism—the electron transfer between bacteria and electrodes to transform metabolism into electrical current. In the current work, we focus on the model electroactive microorganism Geobacter sulfurreducens to explore both the design of new start-up procedures and electrochemical operations. Our chemostat-grown plug and play cells, were able to reduce the start-up period by 20-fold while enhancing chemical oxygen demand (COD removal by more than 6-fold during this period. Moreover, a filter-press based bioreactor was successfully tested for both acetate-supplemented synthetic wastewater and real urban wastewater. This proof-of-concept pre-pilot treatment included a microbial electrolysis cell (MEC followed in time by a microbial fuel cell (MFC to finally generate electrical current of ca. 20 A·m−2 with a power of 10 W·m−2 while removing 42 g COD day−1·m−2. The effective removal of acetate suggests a potential use of this modular technology for treating acetogenic wastewater where Geobacter sulfurreducens outcompetes other organisms.

Minimal RED Cell Pairs Markedly Improve Electrode Kinetics and Power Production in Microbial Reverse Electrodialysis Cells

KAUST Repository

Cusick, Roland D.

2013-12-17

Power production from microbial reverse electrodialysis cell (MRC) electrodes is substantially improved compared to microbial fuel cells (MFCs) by using ammonium bicarbonate (AmB) solutions in multiple RED cell pair stacks and the cathode chamber. Reducing the number of RED membranes pairs while maintaining enhanced electrode performance could help to reduce capital costs. We show here that using only a single RED cell pair (CP), created by operating the cathode in concentrated AmB, dramatically increased power production normalized to cathode area from both acetate (Acetate: from 0.9 to 3.1 W/m 2-cat) and wastewater (WW: 0.3 to 1.7 W/m2), by reducing solution and charge transfer resistances at the cathode. A second RED cell pair increased RED stack potential and reduced anode charge transfer resistance, further increasing power production (Acetate: 4.2 W/m2; WW: 1.9 W/m2). By maintaining near optimal electrode power production with fewer membranes, power densities normalized to total membrane area for the 1-CP (Acetate: 3.1 W/m2-mem; WW: 1.7 W/m2) and 2-CP (Acetate: 1.3 W/m2-mem; WW: 0.6 W/m2) reactors were much higher than previous MRCs (0.3-0.5 W/m2-mem with acetate). While operating at peak power, the rate of wastewater COD removal, normalized to reactor volume, was 30-50 times higher in 1-CP and 2-CP MRCs than that in a single chamber MFC. These findings show that even a single cell pair AmB RED stack can significantly enhance electrical power production and wastewater treatment. © 2013 American Chemical Society.

Minimal RED Cell Pairs Markedly Improve Electrode Kinetics and Power Production in Microbial Reverse Electrodialysis Cells

KAUST Repository

Cusick, Roland D.; Hatzell, Marta; Zhang, Fang; Logan, Bruce E.

2013-01-01

Power production from microbial reverse electrodialysis cell (MRC) electrodes is substantially improved compared to microbial fuel cells (MFCs) by using ammonium bicarbonate (AmB) solutions in multiple RED cell pair stacks and the cathode chamber. Reducing the number of RED membranes pairs while maintaining enhanced electrode performance could help to reduce capital costs. We show here that using only a single RED cell pair (CP), created by operating the cathode in concentrated AmB, dramatically increased power production normalized to cathode area from both acetate (Acetate: from 0.9 to 3.1 W/m 2-cat) and wastewater (WW: 0.3 to 1.7 W/m2), by reducing solution and charge transfer resistances at the cathode. A second RED cell pair increased RED stack potential and reduced anode charge transfer resistance, further increasing power production (Acetate: 4.2 W/m2; WW: 1.9 W/m2). By maintaining near optimal electrode power production with fewer membranes, power densities normalized to total membrane area for the 1-CP (Acetate: 3.1 W/m2-mem; WW: 1.7 W/m2) and 2-CP (Acetate: 1.3 W/m2-mem; WW: 0.6 W/m2) reactors were much higher than previous MRCs (0.3-0.5 W/m2-mem with acetate). While operating at peak power, the rate of wastewater COD removal, normalized to reactor volume, was 30-50 times higher in 1-CP and 2-CP MRCs than that in a single chamber MFC. These findings show that even a single cell pair AmB RED stack can significantly enhance electrical power production and wastewater treatment. © 2013 American Chemical Society.

Purine derivative excretion and microbial protein synthesis in sheep ...

African Journals Online (AJOL)

In a 3 x 3 Latin square design experiment, urinary excretions of purine derivatives (allantoin N, Uric acid N, Xanthine + Hypoxanthine N) were measured and used to estimate microbial N yield in 9 sheep fed roughage- based diet supplemented with 0, 150 and 300g DM grass silage respectively. Daily urinary excretions of ...

The dominant acetate degradation pathway/methanogenic composition in full-scale anaerobic digesters operating under different ammonia levels

DEFF Research Database (Denmark)

Fotidis, Ioannis; Karakashev, Dimitar Borisov; Angelidaki, Irini

2014-01-01

Ammonia is a major environmental factor influencing biomethanation in full-scale anaerobic digesters. In this study, the effect of different ammonia levels on methanogenic pathways and methanogenic community composition of full-scale biogas plants was investigated. Eight full-scale digesters...... operating under different ammonia levels were sampled, and the residual biogas production was followed in fed-batch reactors. Acetate, labelled in the methyl group, was used to determine the methanogenic pathway by following the 14CH4 and 14CO2 production. Fluorescence in situ hybridisation was used...... to determine the methanogenic communities’ composition. Results obtained clearly demonstrated that syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis was the dominant pathway in all digesters with high ammonia levels (2.8–4.57 g NH4 +-N L−1), while acetoclastic methanogenic pathway...

Effects of alfalfa meal on the intestinal microbial diversity and immunity of growing ducks.

Science.gov (United States)

Jiang, J F; Song, X M; Wu, J L; Jiang, Y Q

2014-12-01

This study was conducted to investigate the effects of alfalfa meal diets on the intestinal microbial diversity and immunity of growing egg-type ducks. A total of 128 healthy 7-week-old female egg-type Shaoxing ducks were selected and randomly assigned into four dietary treatments: 0%, 3%, 6% and 9% alfalfa meal for 8 weeks. Each treatment consisted of four replicates of eight ducks each. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was used to characterize the microbiota. The results showed that the DGGE fingerprints of the V6-V8 fragments of the 16S rRNA from the caeca and faeces of ducks fed 3%, 6% and 9% alfalfa meal had significantly higher microbiota species richness than those fed 0% alfalfa meal (p ducks fed 3%, 6% and 9% alfalfa meal was significantly higher than those fed 0% alfalfa meal (p 0.05), and the 3-9% alfalfa meal did not affect the growth performance of the growing egg-type ducks. The proliferation of T and B lymphocytes was significantly greater (p ducks. Dietary alfalfa meal supplementation increases intestinal microbial community diversity and improves of the immune response growing egg-type ducks. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

Genome-guided analysis of physiological and morphological traits of the fermentative acetate oxidizer Thermacetogenium phaeum

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Oehler Dirk

2012-12-01

Full Text Available Abstract Background Thermacetogenium phaeum is a thermophilic strictly anaerobic bacterium oxidizing acetate to CO2 in syntrophic association with a methanogenic partner. It can also grow in pure culture, e.g., by fermentation of methanol to acetate. The key enzymes of homoacetate fermentation (Wood-Ljungdahl pathway are used both in acetate oxidation and acetate formation. The obvious reversibility of this pathway in this organism is of specific interest since syntrophic acetate oxidation operates close to the energetic limitations of microbial life. Results The genome of Th. phaeum is organized on a single circular chromosome and has a total size of 2,939,057 bp. It comprises 3.215 open reading frames of which 75% could be assigned to a gene function. The G+C content is 53.88 mol%. Many CRISPR sequences were found, indicating heavy phage attack in the past. A complete gene set for a phage was found in the genome, and indications of phage action could also be observed in culture. The genome contained all genes required for CO2 reduction through the Wood-Ljungdahl pathway, including two formyl tetrahydrofolate ligases, three carbon monoxide dehydrogenases, one formate hydrogenlyase complex, three further formate dehydrogenases, and three further hydrogenases. The bacterium contains a menaquinone MQ-7. No indications of cytochromes or Rnf complexes could be found in the genome. Conclusions The information obtained from the genome sequence indicates that Th. phaeum differs basically from the three homoacetogenic bacteria sequenced so far, i.e., the sodium ion-dependent Acetobacterium woodii, the ethanol-producing Clostridium ljungdahlii, and the cytochrome-containing Moorella thermoacetica. The specific enzyme outfit of Th. phaeum obviously allows ATP formation both in acetate formation and acetate oxidation.

Changes in the microbial community during the acclimation stages of the methane fermentation for the treatment of glycerol

International Nuclear Information System (INIS)

Dinh, Nga Thi; Hatta, Kohei; Kwon, Sang Hagk; Rollon, Analiza P.; Nakasaki, Kiyohiko

2014-01-01

Granular sludge from a full-scale methane reactor treating brewery wastewater was used as a seed for the treatment of glycerol in a laboratory-scale repeated-batch methane reactor, and the change in the microbial community during the acclimation stages was examined. Two types of substrate solutions, a glucose, sodium acetate, and lactic acid mixture, as well as glycerol, were prepared and fed by mixing the two solutions to increase the ratio, in a stepwise manner, of glycerol from 0% to 100%, while keeping a loading of COD at 2.5 kg m −3  d −1 throughout the fermentation process. Vigorous methane gas production, approximately 580 dm 3  m −3  d −1 , was observed during the acclimation stages. Microbial analysis revealed that both bacterial and archaeal communities changed significantly; bacteria (genus Trichococcus and family Syntrophomonadaceae) became dominant rapidly after the start of acclimation, and archaea belonging to the hydrogenotrophic methanogens (genera Methanobacterium and Methanospirillum), increased gradually with the progress of acclimation. - Highlights: • Acclimation stages to the methane fermentation of glycerol were examined. • Vigorous methane gas production, approximately 580 dm 3  m −3  d −1 , was observed. • Both bacteria and archaea, changed significantly during the acclimation stages. • Bacteria belonging to genus Trichococcus and Syntrophomonadaceae became dominant. • Archaea belonging to the hydrogenotrophic methanogens increased gradually

Changes in gut microbiota in rats fed a high fat diet correlate with obesity-associated metabolic parameters.

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Virginie Lecomte

Full Text Available The gut microbiota is emerging as a new factor in the development of obesity. Many studies have described changes in microbiota composition in response to obesity and high fat diet (HFD at the phylum level. In this study we used 16s RNA high throughput sequencing on faecal samples from rats chronically fed HFD or control chow (n = 10 per group, 16 weeks to investigate changes in gut microbiota composition at the species level. 53.17% dissimilarity between groups was observed at the species level. Lactobacillus intestinalis dominated the microbiota in rats under the chow diet. However this species was considerably less abundant in rats fed HFD (P<0.0001, this being compensated by an increase in abundance of propionate/acetate producing species. To further understand the influence of these species on the development of the obese phenotype, we correlated their abundance with metabolic parameters associated with obesity. Of the taxa contributing the most to dissimilarity between groups, 10 presented significant correlations with at least one of the tested parameters, three of them correlated positively with all metabolic parameters: Phascolarctobacterium, Proteus mirabilis and Veillonellaceae, all propionate/acetate producers. Lactobacillus intestinalis was the only species whose abundance was negatively correlated with change in body weight and fat mass. This species decreased drastically in response to HFD, favouring propionate/acetate producing bacterial species whose abundance was strongly correlated with adiposity and deterioration of metabolic factors. Our observations suggest that these species may play a key role in the development of obesity in response to a HFD.

Synergism of cattle and bison inoculum on ruminal fermentation and select bacterial communities in an artificial rumen (Rusitec fed barley straw

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Daniela B Oss

2016-12-01

Full Text Available This study evaluated the effect of increasing the proportion of bison relative to cattle inoculum on fermentation and microbial populations within an artificial rumen (Rusitec. The experiment was a completely randomized design with a factorial treatment structure (proportion cattle:bison inoculum; 0:100, 33:67, 67:33 and 100:0 replicated in two Rusitec apparatuses (n=8 fermenters. The experiment was 15 d with 8 d of adaptation and 7 d of sampling. Fermenters were fed a diet of 70:30 barley straw:concentrate (DM basis. True digestibility of DM was determined after 48 h of incubation from d 13-15, and daily ammonia (NH3 and volatile fatty acid (VFA production were measured on d 9-12. Protozoa counts were determined at d 9, 11, 13 and 15 and particle-associated bacteria (PAB from d 13-15. Select bacterial populations in the PAB were measured using RT-qPCR. Fermenter was considered the experimental unit and day of sampling as a repeated measure. Increasing the proportion of bison inoculum resulted in a quadratic effect (P0.05. Increasing bison inoculum linearly increased (P<0.05 concentrate aNDF disappearance, total and concentrate N disappearance as well as total daily VFA and acetate production. A positive quadratic response (P<0.05 was observed for daily NH3-N, propionate, butyrate, valerate, isovalerate and isobutyrate production, as well as the acetate:propionate ratio. Increasing the proportion of bison inoculum linearly increased (P<0.05 total protozoa numbers. No effects were observed on pH, total gas and methane production, microbial N synthesis, or copies of 16S rRNA associated with total bacteria, Selenomonas ruminantium or Prevotella bryantii. Increasing bison inoculum had a quadratic effect (P<0.05 on Fibrobacter succinogenes, and tended to linearly (P<0.10 increase Ruminococcus flavefaciens and decrease (P<0.05 Ruminococcus albus copy numbers. In conclusion, bison inoculum increased the degradation of feed protein and fibre. A mixture

Different substrates and starter inocula govern microbial community structures in biogas reactors.

Science.gov (United States)

Satpathy, Preseela; Steinigeweg, Sven; Cypionka, Heribert; Engelen, Bert

2016-01-01

The influence of different starter inocula on the microbial communities in biogas batch reactors fed with fresh maize and maize silage as substrates was investigated. Molecular biological analysis by Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rRNA gene fragments showed that each inoculum bore specific microbial communities with varying predominant phylotypes. Both, bacterial and archaeal DGGE profiles displayed three distinct communities that developed depending on the type of inoculum. Although maize and silage are similar substrates, different communities dominated the lactate-rich silage compared to lactate-free fresh maize. Cluster analysis of DGGE gels showed the communities of the same substrates to be stable with their respective inoculum. Bacteria-specific DGGE analysis revealed a rich diversity with Firmicutes being predominant. The other abundant phylotypes were Bacteroidetes and Synergistetes. Archaea-specific DGGE analysis displayed less diverse community structures, identifying members of the Methanosarcinales as the dominant methanogens present in all the three biogas digesters. In general, the source of inoculum played a significant role in shaping microbial communities. Adaptability of the inoculum to the substrates fed also influenced community compositions which further impacted the rates of biogas production.

Relating Anaerobic Digestion Microbial Community and Process Function.

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Venkiteshwaran, Kaushik; Bocher, Benjamin; Maki, James; Zitomer, Daniel

2015-01-01

Anaerobic digestion (AD) involves a consortium of microorganisms that convert substrates into biogas containing methane for renewable energy. The technology has suffered from the perception of being periodically unstable due to limited understanding of the relationship between microbial community structure and function. The emphasis of this review is to describe microbial communities in digesters and quantitative and qualitative relationships between community structure and digester function. Progress has been made in the past few decades to identify key microorganisms influencing AD. Yet, more work is required to realize robust, quantitative relationships between microbial community structure and functions such as methane production rate and resilience after perturbations. Other promising areas of research for improved AD may include methods to increase/control (1) hydrolysis rate, (2) direct interspecies electron transfer to methanogens, (3) community structure-function relationships of methanogens, (4) methanogenesis via acetate oxidation, and (5) bioaugmentation to study community-activity relationships or improve engineered bioprocesses.

Characterization of Exoelectrogenic Bacteria Enterobacter Strains Isolated from a Microbial Fuel Cell Exposed to Copper Shock Load

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Feng, Cuijie; Li, Jiangwei; Qin, Dan; Chen, Lixiang; Zhao, Feng; Chen, Shaohua; Hu, Hongbo; Yu, Chang-Ping

2014-01-01

Microorganisms capable of generating electricity in microbial fuel cells (MFCs) have gained increasing interest. Here fourteen exoelectrogenic bacterial strains were isolated from the anodic biofilm in an MFC before and after copper (Cu) shock load by Hungate roll-tube technique with solid ferric (III) oxide as an electron acceptor and acetate as an electron donor. Phylogenetic analysis of the 16S rRNA gene sequences revealed that they were all closely related to Enterobacter ludwigii DSM 16688T within the Enterobacteriaceae family, although these isolated bacteria showed slightly different morphology before and after Cu shock load. Two representative strains R2B1 (before Cu shock load) and B4B2 (after Cu shock load) were chosen for further analysis. B4B2 is resistant to 200 mg L−1 of Cu(II) while R2B1 is not, which indicated the potential selection of the Cu shock load. Raman analysis revealed that both R2B1 and B4B2 contained c-type cytochromes. Cyclic voltammetry measurements revealed that strain R2B1 had the capacity to transfer electrons to electrodes. The experimental results demonstrated that strain R2B1 was capable of utilizing a wide range of substrates, including Luria-Bertani (LB) broth, cellulose, acetate, citrate, glucose, sucrose, glycerol and lactose to generate electricity, with the highest current density of 440 mA·m−2 generated from LB-fed MFC. Further experiments indicated that the bacterial cell density had potential correlation with the current density. PMID:25412475

Characterization of exoelectrogenic bacteria enterobacter strains isolated from a microbial fuel cell exposed to copper shock load.

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Cuijie Feng

Full Text Available Microorganisms capable of generating electricity in microbial fuel cells (MFCs have gained increasing interest. Here fourteen exoelectrogenic bacterial strains were isolated from the anodic biofilm in an MFC before and after copper (Cu shock load by Hungate roll-tube technique with solid ferric (III oxide as an electron acceptor and acetate as an electron donor. Phylogenetic analysis of the 16S rRNA gene sequences revealed that they were all closely related to Enterobacter ludwigii DSM 16688T within the Enterobacteriaceae family, although these isolated bacteria showed slightly different morphology before and after Cu shock load. Two representative strains R2B1 (before Cu shock load and B4B2 (after Cu shock load were chosen for further analysis. B4B2 is resistant to 200 mg L-1 of Cu(II while R2B1 is not, which indicated the potential selection of the Cu shock load. Raman analysis revealed that both R2B1 and B4B2 contained c-type cytochromes. Cyclic voltammetry measurements revealed that strain R2B1 had the capacity to transfer electrons to electrodes. The experimental results demonstrated that strain R2B1 was capable of utilizing a wide range of substrates, including Luria-Bertani (LB broth, cellulose, acetate, citrate, glucose, sucrose, glycerol and lactose to generate electricity, with the highest current density of 440 mA·m-2 generated from LB-fed MFC. Further experiments indicated that the bacterial cell density had potential correlation with the current density.

A case of anaphylactoid reaction to acetate in acetate-containing bicarbonate dialysate.

Science.gov (United States)

Misaki, Taro; Suzuki, Yumiko; Naito, Yoshitaka; Shiooka, Tempei; Isozaki, Taisuke

2015-05-01

A 35-year-old man with end-stage kidney disease due to chronic glomerulonephritis was admitted to our hospital to start maintenance hemodialysis (HD). One hour after starting the first session of HD, he experienced general pruritus, urticaria, and dyspnea. Signs and symptoms were resolved by discontinuing HD and administrating an antihistamine drug; HD-associated anaphylactoid reactions were therefore suspected. Over the next few HD sessions, we changed the dialysis membrane, anticoagulant, HD circuit and needle, in that order, but general pruritus and urticaria again appeared within 3 h after starting each session of HD. Finally, when we changed the dialysate from acetate-containing bicarbonate dialysate to acetate-free bicarbonate dialysate, urticaria was clearly less than that seen in previous HD sessions, and subsided after discontinuation of HD. Subsequently, 20 mg of oral prednisolone (PSL) was administered 1 h before starting HD, and the patient did not experience general pruritus, urticaria, or dyspnea after starting the session. When administered acetate-containing bicarbonate dialysate after oral PSL pretreatment, the patient again experienced general pruritus, urticaria and dyspnea. Few reports have been published on the occurrence of anaphylactoid reactions during HD using acetate dialysate. We report a rare case of anaphylactoid reactions with acetate in acetate-containing bicarbonate dialysate that were reduced with the use of acetate-free bicarbonate dialysate and oral PSL pretreatment.

Evaluation of commercially available enzymes, probiotics, or yeast on apparent total-tract nutrient digestion and growth in nursery and finishing pigs fed diets containing corn dried distillers grains with solubles

Science.gov (United States)

The ability of enzymes, direct fed microbials, or yeast to enhance nutrient utilization or growth performance in nursery or finishing pigs fed diets containing increased levels of corn fiber from dried distillers grains with solubles (DDGS) is largely unknown. Ten commercially available feed additiv...

Study and management of atmospheric exhaust gas in acetic acid fermentation developing a new process for alcohol vinegar production; Etude et maitrise des rejets atmospheriques en vinaigrerie, developpement d'un procede nouveau de conduite de la fermentation acetique

Energy Technology Data Exchange (ETDEWEB)

Pochat Bohatier, C

1999-12-06

The aim of the study was to examine emissions of volatile organic compounds (VOCs) during acetic (acid) fermentation. The first part of the study presents the methodology developed to reproduce production cycles for spirit vinegar and to analyse gas effluents. The second part describes the origin and quantification of the emissions (ethanol, acetic acid, acetaldehyde and ethyl acetate). The acetic acid is produced by bacterial metabolism while the ethyl acetate is a result of the chemical reaction of esterification. By modelling the emissions during batch processing we were able to identify the various parameters involved when VOCs are carried along by the fermentation gases. The quantities of ethyl acetate depend on the length of time the diluted alcohol is stored, and on its composition. By using a fed-batch method with a continuous supply of ethanol we could reduce alcohol emissions. The third part of the study develops the kinetics studies carried out to adapt the fed-batch process to acetic acid fermentation. The influence of ethanol, either in terms of deficiency or inhibition, is minimized between 8 and 16 g.1-1. A study of the growth rate of bacteria in relation to the amount of acetic acid showed that the latter was highly inhibitive. There is a critical concentration of acetic acid at which the growth of bacteria stops, and the death rate of the culture increases rapidly. The latter depends on the composition of the culture's medium; the corresponding pH of the concentration is between 2.25 and 2.28. By limiting the formation of ethyl acetate in the diluted alcohol and by controlling the concentration of ethanol at 16 g.l -1 per fermentation, the VOC emissions are reduced by 30% and the yield increases as a result. (author)

Effect of pyridoxine deficiency on cholesterogenesis in rats fed different levels of protein

International Nuclear Information System (INIS)

Okada, Mitsuko; Iwami, Tamako

1977-01-01

Hepatic cholesterol contents in rats fed a 70% or 20% casein diet with or without pyridoxine was determined. In the case of the 70% casein group, pyridoxine-deficient rats showed a higher content than the control. The increment was mainly due to the accumulation of an ester form of the cholesterol. On the other hand, pyridoxine-deficient rats in the 20% casein group showed a slightly lower content. The cholesterol content in liver microsomal fractions was lower in the 20%-casein pyridoxine-deficient group and serum cholesterol level was lower in the 70%-casein pyridoxine-deficient group than those in respective control groups. Incorporation of [ 14 C] acetate into cholesterol was studied using liver slices, and significant stimulation was observed in pyridoxine-deficient rat fed a 20% or 70% casein diet. There was no difference in intestinal cholesterogenesis between the control and the deficient groups. (auth.)

Adaptive Response and Tolerance to Acetic Acid in Saccharomyces cerevisiae and Zygosaccharomyces bailii: A Physiological Genomics Perspective.

Science.gov (United States)

Palma, Margarida; Guerreiro, Joana F; Sá-Correia, Isabel

2018-01-01

Acetic acid is an important microbial growth inhibitor in the food industry; it is used as a preservative in foods and beverages and is produced during normal yeast metabolism in biotechnological processes. Acetic acid is also a major inhibitory compound present in lignocellulosic hydrolysates affecting the use of this promising carbon source for sustainable bioprocesses. Although the molecular mechanisms underlying Saccharomyces cerevisiae response and adaptation to acetic acid have been studied for years, only recently they have been examined in more detail in Zygosaccharomyces bailii . However, due to its remarkable tolerance to acetic acid and other weak acids this yeast species is a major threat in the spoilage of acidic foods and beverages and considered as an interesting alternative cell factory in Biotechnology. This review paper emphasizes genome-wide strategies that are providing global insights into the molecular targets, signaling pathways and mechanisms behind S. cerevisiae and Z. bailii tolerance to acetic acid, and extends this information to other weak acids whenever relevant. Such comprehensive perspective and the knowledge gathered in these two yeast species allowed the identification of candidate molecular targets, either for the design of effective strategies to overcome yeast spoilage in acidic foods and beverages, or for the rational genome engineering to construct more robust industrial strains. Examples of successful applications are provided.

Shift in the microbial ecology of a hospital hot water system following the introduction of an on-site monochloramine disinfection system.

Science.gov (United States)

Baron, Julianne L; Vikram, Amit; Duda, Scott; Stout, Janet E; Bibby, Kyle

2014-01-01

Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system microbial ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the microbial ecology of a hospital's hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing microbial ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on microbial ecology and not solely specific target microorganisms.

Shift in the microbial ecology of a hospital hot water system following the introduction of an on-site monochloramine disinfection system.

Directory of Open Access Journals (Sweden)

Julianne L Baron

Full Text Available Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system microbial ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the microbial ecology of a hospital's hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing microbial ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on microbial ecology and not solely specific target microorganisms.

New Dimensions in Microbial Ecology—Functional Genes in Studies to Unravel the Biodiversity and Role of Functional Microbial Groups in the Environment

Science.gov (United States)

Imhoff, Johannes F.

2016-01-01

During the past decades, tremendous advances have been made in the possibilities to study the diversity of microbial communities in the environment. The development of methods to study these communities on the basis of 16S rRNA gene sequences analysis was a first step into the molecular analysis of environmental communities and the study of biodiversity in natural habitats. A new dimension in this field was reached with the introduction of functional genes of ecological importance and the establishment of genetic tools to study the diversity of functional microbial groups and their responses to environmental factors. Functional gene approaches are excellent tools to study the diversity of a particular function and to demonstrate changes in the composition of prokaryote communities contributing to this function. The phylogeny of many functional genes largely correlates with that of the 16S rRNA gene, and microbial species may be identified on the basis of functional gene sequences. Functional genes are perfectly suited to link culture-based microbiological work with environmental molecular genetic studies. In this review, the development of functional gene studies in environmental microbiology is highlighted with examples of genes relevant for important ecophysiological functions. Examples are presented for bacterial photosynthesis and two types of anoxygenic phototrophic bacteria, with genes of the Fenna-Matthews-Olson-protein (fmoA) as target for the green sulfur bacteria and of two reaction center proteins (pufLM) for the phototrophic purple bacteria, with genes of adenosine-5′phosphosulfate (APS) reductase (aprA), sulfate thioesterase (soxB) and dissimilatory sulfite reductase (dsrAB) for sulfur oxidizing and sulfate reducing bacteria, with genes of ammonia monooxygenase (amoA) for nitrifying/ammonia-oxidizing bacteria, with genes of particulate nitrate reductase and nitrite reductases (narH/G, nirS, nirK) for denitrifying bacteria and with genes of methane