Differences in the catalytic mechanisms of mesophilic and thermophilic indole-3-glycerol phosphate synthase enzymes at their adaptive temperatures

International Nuclear Information System (INIS)

Zaccardi, Margot J.; Mannweiler, Olga; Boehr, David D.

2012-01-01

Highlights: ► Catalytic mechanisms of thermophilic–mesophilic enzymes may differ. ► Product release is rate-determining for thermophilic IGPS at low temperatures. ► But at higher temperatures, proton transfer from the general acid is rate-limiting. ► Rate-determining step is different still for mesophilic IGPS. ► Both chemical and physical steps of catalysis are important for temperature adaptation. -- Abstract: Thermophilic enzymes tend to be less catalytically-active at lower temperatures relative to their mesophilic counterparts, despite having very similar crystal structures. An often cited hypothesis for this general observation is that thermostable enzymes have evolved a more rigid tertiary structure in order to cope with their more extreme, natural environment, but they are also less flexible at lower temperatures, leading to their lower catalytic activity under mesophilic conditions. An alternative hypothesis, however, is that complementary thermophilic–mesophilic enzyme pairs simply operate through different evolutionary-optimized catalytic mechanisms. In this communication, we present evidence that while the steps of the catalytic mechanisms for mesophilic and thermophilic indole-3-glycerol phosphate synthase (IGPS) enzymes are fundamentally similar, the identity of the rate-determining step changes as a function of temperature. Our findings indicate that while product release is rate-determining at 25 °C for thermophilic IGPS, near its adaptive temperature (75 °C), a proton transfer event, involving a general acid, becomes rate-determining. The rate-determining steps for thermophilic and mesophilic IGPS enzymes are also different at their respective, adaptive temperatures with the mesophilic IGPS-catalyzed reaction being rate-limited before irreversible CO 2 release, and the thermophilic IGPS-catalyzed reaction being rate limited afterwards.

Effect of alkaline pretreatment on mesophilic and thermophilic anaerobic digestion of a submerged macrophyte: Inhibition and recovery against dissolved lignin during semi-continuous operation.

Science.gov (United States)

Koyama, Mitsuhiko; Watanabe, Keiko; Kurosawa, Norio; Ishikawa, Kanako; Ban, Syuhei; Toda, Tatsuki

2017-08-01

The long-term effect of alkaline pretreatment on semi-continuous anaerobic digestion (AD) of the lignin-rich submerged macrophyte Potamogeton maackianus was investigated using mesophilic and thermophilic conditions. In pretreated reactors, dissolved lignin accumulated to high levels. CH 4 production under the pretreated condition was higher than that of the untreated condition, but decreased from Days 22 (mesophilic) and 42 (thermophilic). However, CH 4 production subsequently recovered, although dissolved lignin accumulated. Further, the change in the microbial community was observed between conditions. These results suggest that dissolved lignin temporarily inhibited AD, although acclimatization to dissolved lignin occurred during long-term operation. During the steady state period, mesophilic conditions achieved a 42% increase in the CH 4 yield using pretreatment, while thermophilic conditions yielded an 8% increment. Because volatile fatty acids accumulated even after acclimatization during the thermophilic pretreated condition and was discharged with the effluent, improvement of the methanogenic step would enable enhanced CH 4 recovery. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular interactions within the halophilic, thermophilic, and mesophilic prokaryotic ribosomal complexes: clues to environmental adaptation.

Science.gov (United States)

Mallik, Saurav; Kundu, Sudip

2015-01-01

Using the available crystal structures of 50S ribosomal subunits from three prokaryotic species: Escherichia coli (mesophilic), Thermus thermophilus (thermophilic), and Haloarcula marismortui (halophilic), we have analyzed different structural features of ribosomal RNAs (rRNAs), proteins, and of their interfaces. We have correlated these structural features with the environmental adaptation strategies of the corresponding species. While dense intra-rRNA packing is observed in thermophilic, loose intra-rRNA packing is observed in halophilic (both compared to mesophilic). Interestingly, protein-rRNA interfaces of both the extremophiles are densely packed compared to that of the mesophilic. The intersubunit bridge regions are almost devoid of cavities, probably ensuring the proper formation of each bridge (by not allowing any loosely packed region nearby). During rRNA binding, the ribosomal proteins experience some structural transitions. Here, we have analyzed the intrinsically disordered and ordered regions of the ribosomal proteins, which are subjected to such transitions. The intrinsically disordered and disorder-to-order transition sites of the thermophilic and mesophilic ribosomal proteins are simultaneously (i) highly conserved and (ii) slowly evolving compared to rest of the protein structure. Although high conservation is observed at such sites of halophilic ribosomal proteins, but slow rate of evolution is absent. Such differences between thermophilic, mesophilic, and halophilic can be explained from their environmental adaptation strategy. Interestingly, a universal biophysical principle evident by a linear relationship between the free energy of interface formation, interface area, and structural changes of r-proteins during assembly is always maintained, irrespective of the environmental conditions.

Influence of variable feeding on mesophilic and thermophilic co-digestion of Laminaria digitata and cattle manure

International Nuclear Information System (INIS)

Sarker, Shiplu; Møller, Henrik Bjarne; Bruhn, Annette

2014-01-01

Highlights: • Anaerobic co-digestion of L. digitata and cattle manure, at ∼35 and ∼50 °C. • Mesophilic co-digestion showed somewhat stable specific methane, but increased volumetric yield. • Thermophilic co-digester yielded higher methane at higher input of algae compared to control. • Mesophilic co-digester performed better in terms of various parameters except methane yield. - Abstract: In this study the effect of various feeding ratios on mesophilic (∼35 °C) and thermophilic (∼50 °C) co-digestion of brown algae Laminaria digitata and cattle manure was investigated. Algae input of 15% VS caused no influence on specific methane yield from mesophilic co-digester while deteriorated the process parameters such as the development of propionic acid in total volatile fatty acids (tVFA) pattern of the thermophilic co-digester. The accumulation of tVFA continued for the latter reactor as the feeding ratio of algae enhanced to 24% VS, but the specific methane yield improved dramatically. Same rise in feeding once again showed no improvement in specific methane yield from mesophilic co-digester even though the other process parameters stabilized or, enriched such as the gain in average volumetric methane yield. For the last feeding ratio at 41% VS algae, specific methane yield from mesophilic co-digester slightly increased which however was not still comparable with the ultimate methane yield from the cattle manure alone. The thermophilic co-digestion on the other hand yielded maximum specific methane, together with the improvement in different process characteristics, as the feeding of algae maximized at the final stage. The trend of methane production from this reactor nevertheless was sharply downward towards the end of the experiment suggesting that the optimum feeding ratio has already been achieved for the present experimental conditions

ANAEROBIC DIGESTION MODEL ANALYSIS OF THE FERMENTATION PROCESS IN PSYCHROPHILIC AND MESOPHILIC CHAMBER IN ACCORDANCE WITH THE AMOUNT OF BIOGAS SOURCED

Directory of Open Access Journals (Sweden)

Dariusz Zdebik

2015-03-01

Full Text Available The paper presents problems concerning the modelling of anaerobic sludge stabilization, with the additional substrate (waste transported, dairy butchery sewage in psychrophilic fermentation conditions in the range 10–20 °C and mesophilic at 35 °C. Simulation test was conducted in the two digesters. Results of the study allowed to evaluate the effectiveness of conducting these processes in separate chambers, i.e. the psychrophilic and mesophilic chamber. During the simulations, terms of obtaining volatile fatty acids and biogas in conjunction with the operating conditions of the chambers indicated.

Comparing Residue Clusters from Thermophilic and Mesophilic Enzymes Reveals Adaptive Mechanisms.

Science.gov (United States)

Sammond, Deanne W; Kastelowitz, Noah; Himmel, Michael E; Yin, Hang; Crowley, Michael F; Bomble, Yannick J

2016-01-01

Understanding how proteins adapt to function at high temperatures is important for deciphering the energetics that dictate protein stability and folding. While multiple principles important for thermostability have been identified, we lack a unified understanding of how internal protein structural and chemical environment determine qualitative or quantitative impact of evolutionary mutations. In this work we compare equivalent clusters of spatially neighboring residues between paired thermophilic and mesophilic homologues to evaluate adaptations under the selective pressure of high temperature. We find the residue clusters in thermophilic enzymes generally display improved atomic packing compared to mesophilic enzymes, in agreement with previous research. Unlike residue clusters from mesophilic enzymes, however, thermophilic residue clusters do not have significant cavities. In addition, anchor residues found in many clusters are highly conserved with respect to atomic packing between both thermophilic and mesophilic enzymes. Thus the improvements in atomic packing observed in thermophilic homologues are not derived from these anchor residues but from neighboring positions, which may serve to expand optimized protein core regions.

Comparative microbiological-hygienic studies in mesophilic and thermophilic fouling of sewage sludge

Energy Technology Data Exchange (ETDEWEB)

Pohlig-Schmitt, M.; Philipp, W.; Wekerle, J.; Strauch, D.

Investigations concerning the inactivation of microbial pathogens (bacteria, viruses and parasites) during anaerobic, alkaline dignestion of sludge are described. A thermophilic (54/sup 0/C) and a mesophilic (34/sup 0/C) operated biogas model plant were compared from the point of view of hygiene. Is was found that in the thermophilic process Salmonella senftenberg survived 13,5 h, Streptococcus faecium 55 h, Streptococcus faecalis 42 h and Klebsiella pneumoniae 0,5 h. Within 30 min eggs of Ascaris suum lost their infectivity Bovine Parvovirus was inactivated after 1 d to 2 d treatment. Survival times under mesophilic conditions of 13 d for Salmonella senftenberg and more than 8 mouth for Streptococcus faecium were found. Poliovirus Type 1 was inactivated in 8 d while Bovine Parvovirus survived no longer than 15 d. The results obtained in the thermophilic process were compared to those after heat treatment of the test microorganisms in ampules exposed in a wather-bath under defined conditions to 54/sup 0/C. It was found, that the bacteria survived only about half the time in this case. Poliovirus Type 1 was inactivated after 0,75 h and Bovine Parvovirus after 7 d exposure. (orig.RB)

Comparing the Bio-Hydrogen Production Potential of Pretreated Rice Straw Co-Digested with Seeded Sludge Using an Anaerobic Bioreactor under Mesophilic Thermophilic Conditions

Directory of Open Access Journals (Sweden)

Asma Sattar

2016-03-01

Full Text Available Three common pretreatments (mechanical, steam explosion and chemical used to enhance the biodegradability of rice straw were compared on the basis of bio-hydrogen production potential while co-digesting rice straw with sludge under mesophilic (37 °C and thermophilic (55 °C temperatures. The results showed that the solid state NaOH pretreatment returned the highest experimental reduction of LCH (lignin, cellulose and hemi-cellulose content and bio-hydrogen production from rice straw. The increase in incubation temperature from 37 °C to 55 °C increased the bio-hydrogen yield, and the highest experimental yield of 60.6 mL/g VSremoved was obtained under chemical pretreatment at 55 °C. The time required for maximum bio-hydrogen production was found on the basis of kinetic parameters as 36 h–47 h of incubation, which can be used as a hydraulic retention time for continuous bio-hydrogen production from rice straw. The optimum pH range of bio-hydrogen production was observed to be 6.7 ± 0.1–5.8 ± 0.1 and 7.1 ± 0.1–5.8 ± 0.1 under mesophilic and thermophilic conditions, respectively. The increase in temperature was found useful for controlling the volatile fatty acids (VFA under mechanical and steam explosion pretreatments. The comparison of pretreatment methods under the same set of experimental conditions in the present study provided a baseline for future research in order to select an appropriate pretreatment method.

A comparative study of thermophilic and mesophilic anaerobic co-digestion of food waste and wheat straw: Process stability and microbial community structure shifts.

Science.gov (United States)

Shi, Xuchuan; Guo, Xianglin; Zuo, Jiane; Wang, Yajiao; Zhang, Mengyu

2018-05-01

Renewable energy recovery from organic solid waste via anaerobic digestion is a promising way to provide sustainable energy supply and eliminate environmental pollution. However, poor efficiency and operational problems hinder its wide application of anaerobic digestion. The effects of two key parameters, i.e. temperature and substrate characteristics on process stability and microbial community structure were studied using two lab-scale anaerobic reactors under thermophilic and mesophilic conditions. Both the reactors were fed with food waste (FW) and wheat straw (WS). The organic loading rates (OLRs) were maintained at a constant level of 3 kg VS/(m 3 ·d). Five different FW:WS substrate ratios were utilized in different operational phases. The synergetic effects of co-digestion improved the stability and performance of the reactors. When FW was mono-digested, both reactors were unstable. The mesophilic reactor eventually failed due to volatile fatty acid accumulation. The thermophilic reactor had better performance compared to mesophilic one. The biogas production rate of the thermophilic reactor was 4.9-14.8% higher than that of mesophilic reactor throughout the experiment. The shifts in microbial community structures throughout the experiment in both thermophilic and mesophilic reactors were investigated. With increasing FW proportions, bacteria belonging to the phylum Thermotogae became predominant in the thermophilic reactor, while the phylum Bacteroidetes was predominant in the mesophilic reactor. The genus Methanosarcina was the predominant methanogen in the thermophilic reactor, while the genus Methanothrix remained predominant in the mesophilic reactor. The methanogenesis pathway shifted from acetoclastic to hydrogenotrophic when the mesophilic reactor experienced perturbations. Moreover, the population of lignocellulose-degrading microorganisms in the thermophilic reactor was higher than those in mesophilic reactor, which explained the better

Characterisation of community structure of bacteria in parallel mesophilic and thermophilic pilot scale anaerobe sludge digesters.

Science.gov (United States)

Tauber, T; Berta, Brigitta; Székely, Anna J; Gyarmati, I; Kékesi, Katalin; Márialigeti, K; Tóth, Erika M

2007-03-01

The aim of the present work was to compare the microbial communities of a mesophilic and a thermophilic pilot scale anaerobe sludge digester. For studying the communities cultivation independent chemotaxonomical methods (RQ and PLFA analyses) and T-RFLP were applied. Microbial communities of the mesophilic and thermophilic pilot digesters showed considerable differences, both concerning the species present, and their abundance. A Methanosarcina sp. dominated the thermophilic, while a Methanosaeta sp. the mesophilic digester among Archaea. Species diversity of Bacteria was reduced in the thermophilic digester. Based on the quinone patterns in both digesters the dominance of sulphate reducing respiratory bacteria could be detected. The PLFA profiles of the digester communities were similar though in minor components characteristic differences were shown. Level of branched chain fatty acids is slightly lower in the thermophilic digester that reports less Gram positive bacteria. The relative ratio of fatty acids characteristic to Enterobacteriaceae, Bacteroidetes and Clostridia shows differences between the two digesters: their importance generally decreased under thermophilic conditions. The sulphate reducer marker (15:1 and 17:1) fatty acids are present in low quantity in both digesters.

Comparing Residue Clusters from Thermophilic and Mesophilic Enzymes Reveals Adaptive Mechanisms.

Directory of Open Access Journals (Sweden)

Deanne W Sammond

Full Text Available Understanding how proteins adapt to function at high temperatures is important for deciphering the energetics that dictate protein stability and folding. While multiple principles important for thermostability have been identified, we lack a unified understanding of how internal protein structural and chemical environment determine qualitative or quantitative impact of evolutionary mutations. In this work we compare equivalent clusters of spatially neighboring residues between paired thermophilic and mesophilic homologues to evaluate adaptations under the selective pressure of high temperature. We find the residue clusters in thermophilic enzymes generally display improved atomic packing compared to mesophilic enzymes, in agreement with previous research. Unlike residue clusters from mesophilic enzymes, however, thermophilic residue clusters do not have significant cavities. In addition, anchor residues found in many clusters are highly conserved with respect to atomic packing between both thermophilic and mesophilic enzymes. Thus the improvements in atomic packing observed in thermophilic homologues are not derived from these anchor residues but from neighboring positions, which may serve to expand optimized protein core regions.

Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

International Nuclear Information System (INIS)

Niu, Qigui; Takemura, Yasuyuki; Kubota, Kengo; Li, Yu-You

2015-01-01

Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV S in in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages

Comparing mesophilic and thermophilic anaerobic digestion of chicken manure: Microbial community dynamics and process resilience

Energy Technology Data Exchange (ETDEWEB)

Niu, Qigui; Takemura, Yasuyuki; Kubota, Kengo [Department of Civil and Environmental Engineering, Graduate School of Engineering Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Li, Yu-You, E-mail: yyli@epl1.civil.tohoku.ac.jp [Department of Civil and Environmental Engineering, Graduate School of Engineering Tohoku University, 6-6-06 Aza-Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Xi’an University of Architecture and Technology, Xi’an (China)

2015-09-15

Highlights: • Microbial community dynamics and process functional resilience were investigated. • The threshold of TAN in mesophilic reactor was higher than the thermophilic reactor. • The recoverable archaeal community dynamic sustained the process resilience. • Methanosarcina was more sensitive than Methanoculleus on ammonia inhibition. • TAN and FA effects the dynamic of hydrolytic and acidogenic bacteria obviously. - Abstract: While methane fermentation is considered as the most successful bioenergy treatment for chicken manure, the relationship between operational performance and the dynamic transition of archaeal and bacterial communities remains poorly understood. Two continuous stirred-tank reactors were investigated under thermophilic and mesophilic conditions feeding with 10%TS. The tolerance of thermophilic reactor on total ammonia nitrogen (TAN) was found to be 8000 mg/L with free ammonia (FA) 2000 mg/L compared to 16,000 mg/L (FA1500 mg/L) of mesophilic reactor. Biomethane production was 0.29 L/gV S{sub in} in the steady stage and decreased following TAN increase. After serious inhibition, the mesophilic reactor was recovered successfully by dilution and washing stratagem compared to the unrecoverable of thermophilic reactor. The relationship between the microbial community structure, the bioreactor performance and inhibitors such as TAN, FA, and volatile fatty acid was evaluated by canonical correspondence analysis. The performance of methanogenic activity and substrate removal efficiency were changed significantly correlating with the community evenness and phylogenetic structure. The resilient archaeal community was found even after serious inhibition in both reactors. Obvious dynamics of bacterial communities were observed in acidogenic and hydrolytic functional bacteria following TAN variation in the different stages.

Fate of antibiotic resistance genes in mesophilic and thermophilic anaerobic digestion of chemically enhanced primary treatment (CEPT) sludge.

Science.gov (United States)

Jang, Hyun Min; Shin, Jingyeong; Choi, Sangki; Shin, Seung Gu; Park, Ki Young; Cho, Jinwoo; Kim, Young Mo

2017-11-01

Anaerobic digestion (AD) of chemically enhanced primary treatment (CEPT) sludge and non-CEPT (conventional sedimentation) sludge were comparatively operated under mesophilic and thermophilic conditions. The highest methane yield (692.46±0.46mL CH 4 /g VS removed in CEPT sludge) was observed in mesophilic AD of CEPT sludge. Meanwhile, thermophilic conditions were more favorable for the removal of total antibiotic resistance genes (ARGs). In this study, no measurable difference in the fates and removal of ARGs and class 1 integrin-integrase gene (intI1) was observed between treated non-CEPT and CEPT sludge. However, redundancy analysis indicated that shifts in bacterial community were primarily accountable for the variations in ARGs and intI1. Network analysis further revealed potential host bacteria for ARGs and intI1. Copyright © 2017 Elsevier Ltd. All rights reserved.

Changes of resistome, mobilome and potential hosts of antibiotic resistance genes during the transformation of anaerobic digestion from mesophilic to thermophilic.

Science.gov (United States)

Tian, Zhe; Zhang, Yu; Yu, Bo; Yang, Min

2016-07-01

This study aimed to reveal how antibiotic resistance genes (ARGs) and their horizontal and vertical transfer-related items (mobilome and bacterial hosts) respond to the transformation of anaerobic digestion (AD) from mesophilic to thermophilic using one-step temperature increase. The resistomes and mobilomes of mesophilic and thermophilic sludge were investigated using metagenome sequencing, and the changes in 24 representative ARGs belonging to three categories, class 1 integron and bacterial genera during the transition period were further followed using quantitative PCR and 454-pyrosequencing. After the temperature increase, resistome abundance in the digested sludge decreased from 125.97 ppm (day 0, mesophilic) to 50.65 ppm (day 57, thermophilic) with the reduction of most ARG types except for the aminoglycoside resistance genes. Thermophilic sludge also had a smaller mobilome, including plasmids, insertion sequences and integrons, than that of mesophilic sludge, suggesting the lower horizontal transfer potential of ARGs under thermophilic conditions. On the other hand, the total abundance of 18 bacterial genera, which were suggested as the possible hosts for 13 ARGs through network analysis, decreased from 23.27% in mesophilic sludge to 11.92% in thermophilic sludge, indicating fewer hosts for the vertical expansion of ARGs after the increase in temperature. These results indicate that the better reduction of resistome abundance by thermophilic AD might be associated with the decrease of both the horizontal and vertical transferability of ARGs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Mesophilic and Thermophilic Temperature Condition to Biogas Production (Methane from Palm Oil Mill Effluent (POME with Cow Manures

Directory of Open Access Journals (Sweden)

Muhammad Fajar Fajar

2018-01-01

Full Text Available Biogas is an environmentally friendly renewable energy source. Biogas can be used using Palm Oil Mill Effluents (POME. However, the % yield of biogas productivity is still not optimum due to the low conversion. The biogas productivity can be optimized by adding methanogen bacteria which increase the methane production through the anaerobic fermentation process. This study aims to utilize cow manures as the source of methanogen bacteria in methane production from POME. Furthermore, this study specifically aims to obtain the optimum productivity condition of biogas production by the composition ratio of POME and cow manures to the amount of fermentation time at 35oC and 50oC for mesophilic and thermophilic bacteria, respectively. The ratio of POME and cow mature were A1 (100:0, A2 (80:20, A3 (70:30, A4 (60:40, and A5 (0:100. The highest yield of biogas production was A2 ratio using the thermophilic condition which showed 51.33% mol with the total solid decline of 73.43%, COD removal of 77.01%, and BOD removal of 70.02%.

introduction aerobic mesophilic bacteria associated with irish potato

African Journals Online (AJOL)

Ife, Osun State, Nigeria and were analysed for aerobic mesophilic bacterial load. The isolated aerobic ... Of significant note is the high multiple resistance pattern of Bacillus sp. strain B2 which showed ..... by chlorine dioxide. J. Food Science.

Thermal adaptation of mesophilic and thermophilic FtsZ assembly by modulation of the critical concentration.

Directory of Open Access Journals (Sweden)

Luis Concha-Marambio

Full Text Available Cytokinesis is the last stage in the cell cycle. In prokaryotes, the protein FtsZ guides cell constriction by assembling into a contractile ring-shaped structure termed the Z-ring. Constriction of the Z-ring is driven by the GTPase activity of FtsZ that overcomes the energetic barrier between two protein conformations having different propensities to assemble into polymers. FtsZ is found in psychrophilic, mesophilic and thermophilic organisms thereby functioning at temperatures ranging from subzero to >100°C. To gain insight into the functional adaptations enabling assembly of FtsZ in distinct environmental conditions, we analyzed the energetics of FtsZ function from mesophilic Escherichia coli in comparison with FtsZ from thermophilic Methanocaldococcus jannaschii. Presumably, the assembly may be similarly modulated by temperature for both FtsZ orthologs. The temperature dependence of the first-order rates of nucleotide hydrolysis and of polymer disassembly, indicated an entropy-driven destabilization of the FtsZ-GTP intermediate. This destabilization was true for both mesophilic and thermophilic FtsZ, reflecting a conserved mechanism of disassembly. From the temperature dependence of the critical concentrations for polymerization, we detected a change of opposite sign in the heat capacity, that was partially explained by the specific changes in the solvent-accessible surface area between the free and polymerized states of FtsZ. At the physiological temperature, the assembly of both FtsZ orthologs was found to be driven by a small positive entropy. In contrast, the assembly occurred with a negative enthalpy for mesophilic FtsZ and with a positive enthalpy for thermophilic FtsZ. Notably, the assembly of both FtsZ orthologs is characterized by a critical concentration of similar value (1-2 μM at the environmental temperatures of their host organisms. These findings suggest a simple but robust mechanism of adaptation of FtsZ, previously shown

Ability of industrial anaerobic ecosystems to produce methane from ethanol in psychrophilic, mesophilic and thermophilic conditions

International Nuclear Information System (INIS)

Mabala, Jojo Charlie

2012-01-01

The process of anaerobic degradation of organic matter is a natural phenomenon widespread in many ecosystems (eg, marshes, lakes, rice fields, digestive systems of animals and humans). A high microbial diversity is maintained during this process, reflecting a diversity of metabolic pathways involved. When complete, the anaerobic digestion results in the formation of biogas (mixture of methane and carbon dioxide). In terms of biotechnology, anaerobic treatment of organic pollution reduces the volume of waste and generates energy as methane recoverable in several forms (electricity, heat, natural gas, biofuels). Industrial digesters are mostly operated at 35 deg. C or 55 deg. C which requires exogenous energy. The objective of the thesis is to study the adaptability of ecosystems sourced from anaerobic industrial scale reactors treating different range of wastes from different processes to convert ethanol into biogas at various temperatures. The first phase of the study was to adapt, in laboratory reactors ecosystems to their original temperature with a readily biodegradable substrate (ethanol). Then, the performances of microbial communities (the maximum methanogenic potential and degradation kinetics) were estimated on a temperature gradient from 5 deg. C to 55 deg. C in batch reactors. The adaptation phase of the ecosystems in lab-scale reactors showed that the biogas averaged theoretical production and this production was followed by a decrease in reaction time with successive addition of the substrate. In addition, the kinetics of the biogas obtained varied greatly from one ecosystem to another. Molecular fingerprinting profiles (CE-SSCP) of bacterial and archaeal communities were performed at the beginning and at the end of conditioning. These community profiles were compared with each other by principal component analysis (PCA). Bacterial populations that ensured efficient performance were different from those that ensured a good adaptability. In addition, the

In vitro production of thymine dimer by ultroviolet irradiation of DNA from mesophilic and thermophilic bacteria

International Nuclear Information System (INIS)

Yein, F.S.; Stenesh, J.

1989-01-01

Thymine dimer was produced in vitro by ultraviolet irradiation of DNA, isolated from the mesophile Bacillus licheniformis and the thermophile B. stearothermophilus. Irradiation was performed at three different temperaturs (35, 45 and 55 C) and the thymine dimer was isolated and determined. An HPLC procedure was developed that permitted temperature was greater for the thermophile than for the mesophile. Formation of thymine dimer increased with temperature for both organisms but more so for the thermophile; over the temperature range of 35-55 C, the average increase in thymine dimer production for the themrophile was about 4-times that for the mesophile. The melting out temperature, as a function of increasing irradiation temperature, was essentially unchanged for the mesophilic DNA, but decreased progressively for the thermophilic DNA. These results are discussed in terms of the macromolecular theory of to the macromolecular theory of the thermophily. (author). 31 refs.; 4 figs.; 3 tabs

Demand-driven biogas production from sugar beet silage in a novel fixed bed disc reactor under mesophilic and thermophilic conditions.

Science.gov (United States)

Terboven, Christiane; Ramm, Patrice; Herrmann, Christiane

2017-10-01

A newly developed fixed bed disc reactor (FBDR) which combines biofilm formation on biofilm carriers and reactor agitation in one single system was assessed for its applicability to demand-driven biogas production by variable feeding of sugar beet silage. Five different feeding patterns were studied at an organic loading of 4g VS L -1 d -1 under mesophilic and thermophilic conditions. High methane yields of 449-462L N kg VS were reached. Feeding variable punctual loadings caused immediate response with 1.2- to 3.5-fold increase in biogas production rates within 15min. Although variable feeding did not induce process instability, a temporary decrease in pH-value and methane concentration below 40% occurred. Thermophilic temperature was advantageous as it resulted in a more rapid, higher methane production and less pronounced decrease in methane content after feeding. The FBDR was demonstrated to be well-suited for flexible biogas production, but further research and comparison with traditional reactor systems are required. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

OpenAIRE

Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste...

Characterization of the planktonic microbiome in upflow anaerobic sludge blanket reactors during adaptation of mesophilic methanogenic granules to thermophilic operational conditions

DEFF Research Database (Denmark)

Zhu, Xinyu; Treu, Laura; Kougias, Panagiotis

2017-01-01

Upflow anaerobic sludge blanket (UASB) technology refers to reactor technology where granules, i.e. self-immobilised microbial associations, are the biological catalysts involved in the anaerobic digestion process. During the start-up period, UASB reactors operate at relatively long HRT and there......Upflow anaerobic sludge blanket (UASB) technology refers to reactor technology where granules, i.e. self-immobilised microbial associations, are the biological catalysts involved in the anaerobic digestion process. During the start-up period, UASB reactors operate at relatively long HRT...... and therefore the liquid phase of the reactor becomes a favourable environment for microbial growth. The current study aimed to elucidate the dynamicity of the suspended microbial community in UASB reactors, during the transition from mesophilic to thermophilic conditions. High throughput 16S rRNA amplicon...... sequencing was used to characterize the taxonomic composition of the microbiome. The results showed that the microbial community was mainly composed by hydrolytic and fermentative bacteria. Results revealed relevant shifts in the microbial community composition, which is mainly determined by the operational...

Azo dye reduction by mesophilic and thermophilic anaerobic consortia

NARCIS (Netherlands)

Santos, dos A.B.; Madrid, de M.P.; Stams, A.J.M.; Lier, van J.B.; Cervantes, F.J.

2005-01-01

The reduction of the azo dye model compounds Reactive Red 2 (RR2) and Reactive Orange 14 (RO14) by mesophilic (30 C) and thermophilic (55 C) anaerobic consortia was studied in batch assays. The contribution of fermentative and methanogenic microorganisms in both temperatures was evaluated in the

Start-up of a sequential dry anaerobic digestion of paunch under psychrophilic and mesophilic temperatures.

Science.gov (United States)

Nkemka, Valentine Nkongndem; Hao, Xiying

2018-04-01

The present laboratory study evaluated the sequential leach bed dry anaerobic digestion (DAD) of paunch under psychrophilic (22°C) and mesophilic (40°C) temperatures. Three leach bed reactors were operated under the mesophilic temperature in sequence at a solid retention time (SRT) of 40d with a new batch started 27d into the run of the previous one. A total of six batches were operated for 135d. The results showed that the mesophilic DAD of paunch was efficient, reaching methane yields of 126.9-212.1mLg -1 volatile solid (VS) and a VS reduction of 32.9-55.5%. The average daily methane production rate increased from 334.3mLd -1 to 571.4mLd -1 and 825.7mLd -1 when one, two and three leach bed reactors were in operation, respectively. The psychrophilic DAD of paunch was operated under a SRT of 100d and a total of three batches were performed in sequence for 300d with each batch starting after completion of the previous one. Improvements in the methane yield from 93.9 to 107.3 and 148.3mLg -1 VS and VS reductions of 24.8, 30.2 and 38.6% were obtained in the consecutive runs, indicating the adaptation of anaerobic microbes from mesophilic to psychrophilic temperatures. In addition, it took three runs for anaerobic microbes to reduce the volatile fatty acid accumulation observed in the first and second trials. This study demonstrates the potential of renewable energy recovery from paunch under psychrophilic and mesophilic temperatures. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Developing a mesophilic co-culture for direct conversion of cellulose to butanol in consolidated bioprocess.

Science.gov (United States)

Wang, Zhenyu; Cao, Guangli; Zheng, Ju; Fu, Defeng; Song, Jinzhu; Zhang, Junzheng; Zhao, Lei; Yang, Qian

2015-01-01

Consolidated bioprocessing (CBP) of butanol production from cellulosic biomass is a promising strategy for cost saving compared to other processes featuring dedicated cellulase production. CBP requires microbial strains capable of hydrolyzing biomass with enzymes produced on its own with high rate and high conversion and simultaneously produce a desired product at high yield. However, current reported butanol-producing candidates are unable to utilize cellulose as a sole carbon source and energy source. Consequently, developing a co-culture system using different microorganisms by taking advantage of their specific metabolic capacities to produce butanol directly from cellulose in consolidated bioprocess is of great interest. This study was mainly undertaken to find complementary organisms to the butanol producer that allow simultaneous saccharification and fermentation of cellulose to butanol in their co-culture under mesophilic condition. Accordingly, a highly efficient and stable consortium N3 on cellulose degradation was first developed by multiple subcultures. Subsequently, the functional microorganisms with 16S rRNA sequences identical to the denaturing gradient gel electrophoresis (DGGE) profile were isolated from consortium N3. The isolate Clostridium celevecrescens N3-2 exhibited higher cellulose-degrading capability was thus chosen as the partner strain for butanol production with Clostridium acetobutylicum ATCC824. Meanwhile, the established stable consortium N3 was also investigated to produce butanol by co-culturing with C. acetobutylicum ATCC824. Butanol was produced from cellulose when C. acetobutylicum ATCC824 was co-cultured with either consortium N3 or C. celevecrescens N3-2. Co-culturing C. acetobutylicum ATCC824 with the stable consortium N3 resulted in a relatively higher butanol concentration, 3.73 g/L, and higher production yield, 0.145 g/g of glucose equivalent. The newly isolated microbial consortium N3 and strain C. celevecrescens N3

Functional responses and adaptation of mesophilic microbial communities to psychrophilic anaerobic digestion.

Science.gov (United States)

Gunnigle, Eoin; Nielsen, Jeppe L; Fuszard, Matthew; Botting, Catherine H; Sheahan, Jerome; O'Flaherty, Vincent; Abram, Florence

2015-12-01

Psychrophilic (functions. Methanomicrobiales abundance increased at low temperature, which correlated with an increased contribution of CH4 production from hydrogenotrophic methanogenesis at 15°C. Methanosarcinales utilized acetate and H2/CO2 as CH4 precursors at both temperatures and a partial shift from acetoclastic to hydrogenotrophic methanogenesis was observed for this archaeal population at 15°C. An upregulation of protein expression was reported at low temperature as well as the detection of chaperones indicating that mesophilic communities experienced stress during long-term exposure to 15°C. Overall, changes in microbial community structure and function were found to underpin the adaptation of mesophilic sludge to psychrophilic AD. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Influence of moisture conditions and mineralization of soil solution on structure of litter macrofauna of the deciduous forests of Ukraine steppe zone

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V. V. Brygadyrenko

2015-02-01

Full Text Available The accounting of litter mesofauna was carried out in the territory of Dnipropetrovsk, Zaporizhzhya, Nikolaev,Donetsk regions of Ukrainein the natural forest ecosystems in 2001–2014. 339 forest ecosystems were surveyed; xeromesophilic conditions of moistening were characteristic for 47 trial sites, mesophilic conditions – for 99 sites, hygro-mesophilic conditions – for 50 sites, meso-hygrophilic conditions – for 89 sites, hygrophilic conditions – for 54 sites; trophotope C was represented by 35 trial sites, Dc – by 44, Dac – by 76, Dn – by 128, De – by 37, E – by 19 forest ecosystems, accordingly. The relative number of saprophages reaches maximum values in hygro-mesophilic, meso-hygrophilic and hygrophilic conditions, and minimum values – in mesophilic conditions of moistening. The share of rare species is maximum in hygro-mesophilic conditions of moistening. The minimum quantity of mass species is also observed in conditions of hygro-mesophilic and meso-hygrophilic deciduous forests. With the growth of moistening of the soil, quantity of species of Carabidae, Formicidae and other dominant families remains without significant changes. The relative number of Formicidae is maximum in xeromesophilic and mesophilic conditions of soil moistening. In these hygrotopes, as well as in hygro-mesophilic conditions of moistening the Julidae numbers are maximum. The Isopoda percent in mesofauna significantly grows in meso-hygrophilic and hygrophilic conditions of moistening. The share of other dominant taxonomical groups in the structure of litter mesofauna remains without significant changes in numbers. In the majority of the analysed hygrotopes 7–8 families are withing the structure of dominants. In the conditions of salinization (trophotopes De and E, and also on light sandy loam soils, the numbers of litter mesofauna decrease. Share of saprophages is minimum in trophotopes Dc and E, while it increases in trophotopes C, Dac, Dn

Converting mesophilic upflow sludge blanket (UASB) reactors to thermophilic by applying axenic methanogenic culture bioaugmentation

DEFF Research Database (Denmark)

Zhu, Xinyu; Treu, Laura; Kougias, Panagiotis G.

2018-01-01

on the microbial consortium. The adaptation of microbial community to a new environment or condition can be accelerated by a process known as “bioaugmentation” or “microbial community manipulation”, during which exogenous microorganisms harbouring specific metabolic activities are introduced to the reactor....... The aim of the current study was to rapidly convert the operational temperature of up-flow anaerobic sludge blanket (UASB) reactors from mesophilic to thermophilic conditions by applying microbial community manipulation techniques. Three different bioaugmentation strategies were compared and it was proven...... that the injection of axenic methanogenic culture was the most efficient approach leading to improved biomethanation process with 40% higher methane production rate compared to the control reactor. Microbial community analyses revealed that during bioaugmentation, the exogenous hydrogenotrophic methanogen could...

Mesophilic and thermophilic anaerobic biodegradability of water hyacinth pre-treated at 80 degrees C.

Science.gov (United States)

Ferrer, Ivet; Palatsi, Jordi; Campos, Elena; Flotats, Xavier

2010-10-01

Water hyacinth (Eichornia crassipes) is a fast growing aquatic plant which causes environmental problems in continental water bodies. Harvesting and handling this plant becomes an issue, and focus has been put on the research of treatment alternatives. Amongst others, energy production through biomethanation has been proposed. The aim of this study was to assess the anaerobic biodegradability of water hyacinth under mesophilic and thermophilic conditions. The effect of a thermal sludge pre-treatment at 80 degrees C was also evaluated. To this end, anaerobic biodegradability tests were carried out at 35 degrees C and 55 degrees C, with raw and pre-treated water hyacinth. According to the results, the thermal pre-treatment enhanced the solubilisation of water hyacinth (i.e. increase in the soluble to total chemical oxygen demand (COD)) from 4% to 12% after 30 min. However, no significant effect was observed on the methane yields (150-190 L CH(4)/kg volatile solids). Initial methane production rates for thermophilic treatments were two fold those of mesophilic ones (6-6.5L vs. 3-3.5 L CH(4)/kg COD x day). Thus, higher methane production rates might be expected from thermophilic reactors working at short retention times. The study of longer low temperature pre-treatments or pre-treatments at elevated temperatures coupled to thermophilic reactors should be considered in the future. (c) 2009 Elsevier Ltd. All rights reserved.

Mesophilic and thermophilic anaerobic biodegradability of water hyacinth pre-treated at 80 oC

International Nuclear Information System (INIS)

Ferrer, Ivet; Palatsi, Jordi; Campos, Elena; Flotats, Xavier

2010-01-01

Water hyacinth (Eichornia crassipes) is a fast growing aquatic plant which causes environmental problems in continental water bodies. Harvesting and handling this plant becomes an issue, and focus has been put on the research of treatment alternatives. Amongst others, energy production through biomethanation has been proposed. The aim of this study was to assess the anaerobic biodegradability of water hyacinth under mesophilic and thermophilic conditions. The effect of a thermal sludge pre-treatment at 80 o C was also evaluated. To this end, anaerobic biodegradability tests were carried out at 35 o C and 55 o C, with raw and pre-treated water hyacinth. According to the results, the thermal pre-treatment enhanced the solubilisation of water hyacinth (i.e. increase in the soluble to total chemical oxygen demand (COD)) from 4% to 12% after 30 min. However, no significant effect was observed on the methane yields (150-190 L CH 4 /kg volatile solids). Initial methane production rates for thermophilic treatments were two fold those of mesophilic ones (6-6.5 L vs. 3-3.5 L CH 4 /kg COD.day). Thus, higher methane production rates might be expected from thermophilic reactors working at short retention times. The study of longer low temperature pre-treatments or pre-treatments at elevated temperatures coupled to thermophilic reactors should be considered in the future.

Mesophilic and thermophilic anaerobic digestion of primary and secondary sludge. Effect of pre-treatment at elevated temperature

DEFF Research Database (Denmark)

Gavala, Hariklia N.; Yenal, U.; Skiadas, Ioannis V.

2003-01-01

Anaerobic digestion is an appropriate technique for the treatment of sludge before final disposal and it is employed worldwide as the oldest and most important process for sludge stabilization. In general, mesophilic anaerobic digestion of sewage sludge is more widely used compared to thermophilic...... digestion. Furthermore, thermal pre-treatment is suitable for the improvement of stabilization, enhancement of dewatering of the sludge, reduction of the numbers of pathogens and could be realized at relatively low cost especially at low temperatures. The present study investigates (a) the differences...... between mesophilic and thermophilic anaerobic digestion of sludge and (b) the effect of the pretreatment at 70 degreesC on mesophilic and thermophilic anaerobic digestion of primary and secondary sludge. The pretreatment step showed very positive effect on the methane potential and production rate upon...

Selection of mesophilic microorganisms with biodesulfuration capacity

International Nuclear Information System (INIS)

Madero, A; Mogollon, L. I; Mora, A.L; Osorio, L.F

1998-01-01

The development of bio desulfurization (BDS) processes for hydrocarbons requires fast and reliable methods for the screening of microorganisms. This work shows the results of the screening process for indigenous Colombian strains with a BDS potential capacity. The main criteria for the screening were the qualitative and quantitative determination of 2-hydroxybiphenyl (2-HBP) as the typical metabolite of the 4S specific pathway. Microorganisms were cultured by two methodologies, A and B, using DBT as the model compound. The quantitative determination of metabolites was made by HPLC. Thirteen strains were evaluated, including the strain Rhodococcus rhodocrous IGTS8, by methods A and B. In method A, the inoculum was exposed to DBT since the beginning of the culture. Method B, employed two stages: (i) Growth period under limiting sulfur conditions, (ii) Transforming period, in which the pre-grown inoculum was exposed to the organic sulfur substrate. The culture of mesophilic microorganisms isolated by method B, served to find a mechanism for the organic sulfur metabolism, and the evaluation of the sulfur removal capability of five indigenous strains. In the cultures of these strains, 2- hydroxybiphenyl (2-HBP) was detected as a byproduct of DBT metabolism, both qualitatively and quantitatively

the influence of the dressing procedure on the (mesophilic) bacterial ...

African Journals Online (AJOL)

for 24 hours to determine the mesophilic bacterial count. Point values were transformed to/x + t before analyses of variance were conducted. Least significant difference (L.S.D.) tests were per- formed on all the mean values obtained from the carcass sites and the dressing line positions except in the case of position I of the ...

Shifts in bacterial and archaeal community structures during the batch biomethanation of Ulva biomass under mesophilic conditions.

Science.gov (United States)

Kim, Jaai; Jung, Heejung; Lee, Changsoo

2014-10-01

Mesophilic biomethanation of Ulva biomass was performed in a batch bioreactor, and a high organic removal of 77% was obtained on the basis of chemical oxygen demand (COD) after a month of operation. The estimated methane yield was 0.43 ± 0.02 L CH4/g COD(removed) which is close to the theoretical methane potential. Transitions of bacterial and archaeal community structures, associated with process performance data, were investigated using a combination of molecular fingerprinting and biostatistical tools. During the operation, archaeal community structure had no significant changes while bacterial community structure shifted continuously and dynamically. The reactor completely stabilized volatile fatty acids (primarily acetate and propionate) accumulated from the acidogenesis phase, with Methanosaeta- and Methanolinea-related microbes respectively being the main aceticlastic and hydrogenotrophic methanogens. Methanolinea- and Syntrophobacter-related populations were likely the key members to form a syntrophic propionate-degrading consortium. A Methanolinea-related population was likely the dominant methane producer in the experimental reactor. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mesophilic anaerobic co-digestion of municipal solid waste and sewage sludge

DEFF Research Database (Denmark)

Aghdam, Ehsan Fathi; Kinnunen, V.; Rintala, Jukka A.

2015-01-01

This paper presents mesophilic anaerobic digestion (AD) of organic fraction of municipal solid waste (OFMSW), biowaste (BW), sewage sludge (SS), and co-digestion of BW and SS. Average methane yields of 386 ± 54, 385 ± 82, 198 ± 14, and 318 ± 59 L CH4/kg volatile solids (VS) were obtained for OFMSW...

Performance evaluation of a completely stirred anaerobic reactor treating pig manure at a low range of mesophilic conditions

International Nuclear Information System (INIS)

Guo, Jianbin; Dong, Renjie; Clemens, Joachim; Wang, Wei

2013-01-01

Highlights: • The biogas process can run stably at 20 °C at extremely low OLR after long-term acclimation of bacteria. • A biogas plant running at 28 °C seems as efficient as that operated at 38 °C at low OLR of 1.3 g ODM L −1 d −1 . • Lower temperature operation is inadvisable for the commercial biogas plant running at rather high OLR. • The estimated sludge yield at 28 °C is higher than that at 38 °C. - Abstract: Many Chinese biogas plants run in the lower range of mesophilic conditions. This study evaluated the performance of a completely stirred anaerobic reactor treating pig manure at different temperatures (20, 28 and 38 °C). The start-up phase of the reactor at 20 °C was very long and extremely poor performance was observed with increasing organic loading rate (OLR). At an OLR of 4.3 g ODM L −1 d −1 , methane production at 28 °C was comparable (3% less) with that at 38 °C, but the risk of acidification was high at 28 °C. At low OLR (1.3 g ODM L −1 d −1 ), the biogas process appeared stable at 28 °C and gave same methane yields as compared to the reactor operating at 38 °C. The estimated sludge yield at 28 °C was 0.065 g VSS g −1 COD removed, which was higher than that at 38 °C (0.016 g VSS g −1 COD removed )

Stability of the 'L12 stalk' in ribosomes from mesophilic and (hyper)thermophilic Archaea and Bacteria.

Science.gov (United States)

Shcherbakov, D; Dontsova, M; Tribus, M; Garber, M; Piendl, W

2006-01-01

The ribosomal stalk complex, consisting of one molecule of L10 and four or six molecules of L12, is attached to 23S rRNA via protein L10. This complex forms the so-called 'L12 stalk' on the 50S ribosomal subunit. Ribosomal protein L11 binds to the same region of 23S rRNA and is located at the base of the 'L12 stalk'. The 'L12 stalk' plays a key role in the interaction of the ribosome with translation factors. In this study stalk complexes from mesophilic and (hyper)thermophilic species of the archaeal genus Methanococcus and from the Archaeon Sulfolobus solfataricus, as well as from the Bacteria Escherichia coli, Geobacillus stearothermophilus and Thermus thermophilus, were overproduced in E.coli and purified under non-denaturing conditions. Using filter-binding assays the affinities of the archaeal and bacterial complexes to their specific 23S rRNA target site were analyzed at different pH, ionic strength and temperature. Affinities of both archaeal and bacterial complexes for 23S rRNA vary by more than two orders of magnitude, correlating very well with the growth temperatures of the organisms. A cooperative effect of binding to 23S rRNA of protein L11 and the L10/L12(4) complex from mesophilic and thermophilic Archaea was shown to be temperature-dependent.

Comprehensive microbial analysis of combined mesophilic anaerobic-thermophilic aerobic process treating high-strength food wastewater.

Science.gov (United States)

Jang, Hyun Min; Ha, Jeong Hyub; Park, Jong Moon; Kim, Mi-Sun; Sommer, Sven G

2015-04-15

A combined mesophilic anaerobic-thermophilic aerobic process was used to treat high-strength food wastewater in this study. During the experimental period, most of solid residue from the mesophilic anaerobic reactor (R1) was separated by centrifugation and introduced into the thermophilic aerobic reactor (R2) for further digestion. Then, thermophilic aerobically-digested sludge was reintroduced into R1 to enhance reactor performance. The combined process was operated with two different Runs: Run I with hydraulic retention time (HRT) = 40 d (corresponding OLR = 3.5 kg COD/m(3) d) and Run II with HRT = 20 d (corresponding OLR = 7 kg COD/m(3)). For a comparison, a single-stage mesophilic anaerobic reactor (R3) was operated concurrently with same OLRs and HRTs as the combined process. During the overall digestion, all reactors showed high stability without pH control. The combined process demonstrated significantly higher organic matter removal efficiencies (over 90%) of TS, VS and COD and methane production than did R3. Quantitative real-time PCR (qPCR) results indicated that higher populations of both bacteria and archaea were maintained in R1 than in R3. Pyrosequencing analysis revealed relatively high abundance of phylum Actinobacteria in both R1 and R2, and a predominance of phyla Synergistetes and Firmicutes in R3 during Run II. Furthermore, R1 and R2 shared genera (Prevotella, Aminobacterium, Geobacillus and Unclassified Actinobacteria), which suggests synergy between mesophilic anaerobic digestion and thermophilic aerobic digestion. For archaea, in R1 methanogenic archaea shifted from genus Methanosaeta to Methanosarcina, whereas genera Methanosaeta, Methanobacterium and Methanoculleus were predominant in R3. The results demonstrated dynamics of key microbial populations that were highly consistent with an enhanced reactor performance of the combined process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biodegradation of phthalate esters during the mesophilic anaerobic digestion of sludge

DEFF Research Database (Denmark)

Gavala, Hariklia N.; Alatriste-Mondragon, Felipe; Iranpour, R.

2003-01-01

of di-n-butyl phthalate (DBP), di-ethyl phthalate (DEP) and di-ethylhexyl phthalate (DEHP) was investigated and their relative rates of anaerobic degradation were calculated. Also, the biological removal of PAE during the anaerobic digestion of sludge in bench-scale digesters was investigated using DBP...... and DEHP as model compounds of one biodegradable and one recalcitrant PAE respectively. The degradation of all the PAE tested in this study (DEP, DBP and DEHP) is adequately described by first-order kinetics. Batch and continuous experiments showed that DEP and DBP present in sludge are rapidly degraded...... under mesophilic anaerobic conditions (a first-order kinetic constant of 8.04 x 10(-2) and 13.69 x 10(-2) -4.35 day(-1) respectively) while DEHP is degraded at a rate between one to two orders of magnitude lower (0.35 x 10(-2) -3.59 x 10(-2) day(-1)). It is of high significance that experiments...

Occurrence and molecular characterization of cultivable mesophilic and thermophilic obligate anaerobic bacteria isolated from paper mills.

Science.gov (United States)

Suihko, Maija-Liisa; Partanen, Laila; Mattila-Sandholm, Tiina; Raaska, Laura

2005-08-01

The aim of this work was to characterize the cultivable obligate anaerobic bacterial population in paper mill environments. A total of 177 anaerobically grown bacterial isolates were screened for aerotolerance, from which 67 obligate anaerobes were characterized by automated ribotyping and 41 were further identified by partial 16S rDNA sequencing. The mesophilic isolates indicated 11 different taxa (species) within the genus Clostridium and the thermophilic isolates four taxa within the genus Thermoanaerobacterium and one within Thermoanaerobacter (both formerly Clostridium). The most widespread mesophilic bacterium was closely related to C. magnum and occurred in three of four mills. One mill was contaminated with a novel mesophilic bacterium most closely related to C. thiosulfatireducens. The most common thermophile was T. thermosaccharolyticum, occurring in all four mills. The genetic relationships of the mill isolates to described species indicated that most of them are potential members of new species. On the basis of identical ribotypes clay could be identified to be the contamination source of thermophilic bacteria. Automated ribotyping can be a useful tool for the identification of clostridia as soon as comprehensive identification libraries are available.

Leuconostoc Strains Unable to Split a Lactose Analogue Revealed by Characterisation of Mesophilic Dairy Starters

Directory of Open Access Journals (Sweden)

Maarit Mäki

2005-01-01

Full Text Available Mesophilic starter cultures used in dairy industry have been traditionally characterised by metabolic and biochemical methods. As closely related species of lactic acid bacteria have often only minor differences in phenotypic traits, which may also be variable within certain species, clear identification is often complicated. Therefore, techniques of molecular biology have been applied for rapid detection and differentiation of lactic acid bacteria. In this work, some bacterial clones isolated from mesophilic starters, which were preliminary identified as lactococci by phenotypic methods, were found to be Leuconostoc strains by both PCR and PFGE. According to the results, genotypic differentiation methods used in combination with phenotypic tests provide a fast and convenient way to reliably identify lactic acid bacteria displaying atypical metabolic characteristics.

Mesophilic co-digestion of palm oil mill effluent and empty fruit bunches.

Science.gov (United States)

Kim, Sang-Hyoun; Choi, Seon-Mi; Ju, Hyun-Jun; Jung, Jin-Young

2013-01-01

The palm oil mill industry generates palm oil mill effluent (POME) and empty fruit bunches (EFB) as by-products. This study reports the mesophilic co-digestion of POME with EFB. The biochemical methane potential (BMP) of POME and EFB was 0.397 L CH4/g volatile solids (VS) and 0.264 L CH4/g VS, respectively. In a series of batch tests at various EFB to POME ratios, the maximum methane production rate was achieved at an EFB:POME ratio of 0.25-0.31:1. Performance data from lab-scale digesters confirmed the positive synergism by the addition of EFB to POME, which was attributed to the balanced chemical composition, for example the chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio. The EFB addition enhanced the acceptable organic loading rate, methane production, COD removal, and microbial activity. The mesophilic co-digestion of POME and EFB promises to be a viable recycling method to alleviate pollution problems and recover renewable energy in the palm oil mill industry.

Comparison of the microbial communities in solid-state anaerobic digestion (SS-AD) reactors operated at mesophilic and thermophilic temperatures.

Science.gov (United States)

Li, Yueh-Fen; Nelson, Michael C; Chen, Po-Hsu; Graf, Joerg; Li, Yebo; Yu, Zhongtang

2015-01-01

The microbiomes involved in liquid anaerobic digestion process have been investigated extensively, but the microbiomes underpinning solid-state anaerobic digestion (SS-AD) are poorly understood. In this study, microbiome composition and temporal succession in batch SS-AD reactors, operated at mesophilic or thermophilic temperatures, were investigated using Illumina sequencing of 16S rRNA gene amplicons. A greater microbial richness and evenness were found in the mesophilic than in the thermophilic SS-AD reactors. Firmicutes accounted for 60 and 82 % of the total Bacteria in the mesophilic and in the thermophilic SS-AD reactors, respectively. The genus Methanothermobacter dominated the Archaea in the thermophilic SS-AD reactors, while Methanoculleus predominated in the mesophilic SS-AD reactors. Interestingly, the data suggest syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis as an important pathway for biogas production during the thermophilic SS-AD. Canonical correspondence analysis (CCA) showed that temperature was the most influential factor in shaping the microbiomes in the SS-AD reactors. Thermotogae showed strong positive correlation with operation temperature, while Fibrobacteres, Lentisphaerae, Spirochaetes, and Tenericutes were positively correlated with daily biogas yield. This study provided new insight into the microbiome that drives SS-AD process, and the findings may help advance understanding of the microbiome in SS-AD reactors and the design and operation of SS-AD systems.

Thermophilic versus Mesophilic Anaerobic Digestion of Sewage Sludge: A Comparative Review

Directory of Open Access Journals (Sweden)

Getachew D. Gebreeyessus

2016-06-01

Full Text Available During advanced biological wastewater treatment, a huge amount of sludge is produced as a by-product of the treatment process. Hence, reuse and recovery of resources and energy from the sludge is a big technological challenge. The processing of sludge produced by Wastewater Treatment Plants (WWTPs is massive, which takes up a big part of the overall operational costs. In this regard, anaerobic digestion (AD of sewage sludge continues to be an attractive option to produce biogas that could contribute to the wastewater management cost reduction and foster the sustainability of those WWTPs. At the same time, AD reduces sludge amounts and that again contributes to the reduction of the sludge disposal costs. However, sludge volume minimization remains, a challenge thus improvement of dewatering efficiency is an inevitable part of WWTP operation. As a result, AD parameters could have significant impact on sludge properties. One of the most important operational parameters influencing the AD process is temperature. Consequently, the thermophilic and the mesophilic modes of sludge AD are compared for their pros and cons by many researchers. However, most comparisons are more focused on biogas yield, process speed and stability. Regarding the biogas yield, thermophilic sludge AD is preferred over the mesophilic one because of its faster biochemical reaction rate. Equally important but not studied sufficiently until now was the influence of temperature on the digestate quality, which is expressed mainly by the sludge dewateringability, and the reject water quality (chemical oxygen demand, ammonia nitrogen, and pH. In the field of comparison of thermophilic and mesophilic digestion process, few and often inconclusive research, unfortunately, has been published so far. Hence, recommendations for optimized technologies have not yet been done. The review presented provides a comparison of existing sludge AD technologies and the gaps that need to be filled so

Thermophilic versus Mesophilic Anaerobic Digestion of Sewage Sludge: A Comparative Review

Science.gov (United States)

Gebreeyessus, Getachew D.; Jenicek, Pavel

2016-01-01

During advanced biological wastewater treatment, a huge amount of sludge is produced as a by-product of the treatment process. Hence, reuse and recovery of resources and energy from the sludge is a big technological challenge. The processing of sludge produced by Wastewater Treatment Plants (WWTPs) is massive, which takes up a big part of the overall operational costs. In this regard, anaerobic digestion (AD) of sewage sludge continues to be an attractive option to produce biogas that could contribute to the wastewater management cost reduction and foster the sustainability of those WWTPs. At the same time, AD reduces sludge amounts and that again contributes to the reduction of the sludge disposal costs. However, sludge volume minimization remains, a challenge thus improvement of dewatering efficiency is an inevitable part of WWTP operation. As a result, AD parameters could have significant impact on sludge properties. One of the most important operational parameters influencing the AD process is temperature. Consequently, the thermophilic and the mesophilic modes of sludge AD are compared for their pros and cons by many researchers. However, most comparisons are more focused on biogas yield, process speed and stability. Regarding the biogas yield, thermophilic sludge AD is preferred over the mesophilic one because of its faster biochemical reaction rate. Equally important but not studied sufficiently until now was the influence of temperature on the digestate quality, which is expressed mainly by the sludge dewateringability, and the reject water quality (chemical oxygen demand, ammonia nitrogen, and pH). In the field of comparison of thermophilic and mesophilic digestion process, few and often inconclusive research, unfortunately, has been published so far. Hence, recommendations for optimized technologies have not yet been done. The review presented provides a comparison of existing sludge AD technologies and the gaps that need to be filled so as to optimize

Enrichment of acetogenic bacteria in high rate anaerobic reactors under mesophilic and thermophilic conditions.

Science.gov (United States)

Ryan, P; Forbes, C; McHugh, S; O'Reilly, C; Fleming, G T A; Colleran, E

2010-07-01

The objective of the current study was to expand the knowledge of the role of acetogenic Bacteria in high rate anaerobic digesters. To this end, acetogens were enriched by supplying a variety of acetogenic growth supportive substrates to two laboratory scale high rate upflow anaerobic sludge bed (UASB) reactors operated at 37 degrees C (R1) and 55 degrees C (R2). The reactors were initially fed a glucose/acetate influent. Having achieved high operational performance and granular sludge development and activity, both reactors were changed to homoacetogenic bacterial substrates on day 373 of the trial. The reactors were initially fed with sodium vanillate as a sole substrate. Although % COD removal indicated that the 55 degrees C reactor out performed the 37 degrees C reactor, effluent acetate levels from R2 were generally higher than from R1, reaching values as high as 5023 mg l(-1). Homoacetogenic activity in both reactors was confirmed on day 419 by specific acetogenic activity (SAA) measurement, with higher values obtained for R2 than R1. Sodium formate was introduced as sole substrate to both reactors on day 464. It was found that formate supported acetogenic activity at both temperatures. By the end of the trial, no specific methanogenic activity (SMA) was observed against acetate and propionate indicating that the methane produced was solely by hydrogenotrophic Archaea. Higher SMA and SAA values against H(2)/CO(2) suggested development of a formate utilising acetogenic population growing in syntrophy with hydrogenotrophic methanogens. Throughout the formate trial, the mesophilic reactor performed better overall than the thermophilic reactor. Copyright 2010 Elsevier Ltd. All rights reserved.

Discrimination of thermophilic and mesophilic proteins

Directory of Open Access Journals (Sweden)

Vaisman Iosif I

2010-05-01

Full Text Available Abstract Background There is a considerable literature on the source of the thermostability of proteins from thermophilic organisms. Understanding the mechanisms for this thermostability would provide insights into proteins generally and permit the design of synthetic hyperstable biocatalysts. Results We have systematically tested a large number of sequence and structure derived quantities for their ability to discriminate thermostable proteins from their non-thermostable orthologs using sets of mesophile-thermophile ortholog pairs. Most of the quantities tested correspond to properties previously reported to be associated with thermostability. Many of the structure related properties were derived from the Delaunay tessellation of protein structures. Conclusions Carefully selected sequence based indices discriminate better than purely structure based indices. Combined sequence and structure based indices improve performance somewhat further. Based on our analysis, the strongest contributors to thermostability are an increase in ion pairs on the protein surface and a more strongly hydrophobic interior.

Characterization of Probiotic Fermented Milk Prepared by Different Inoculation Size of Mesophilic and Thermophilic Lactic Acid Bacteria

Directory of Open Access Journals (Sweden)

Sara Nasiri Boosjin

2016-10-01

Full Text Available Background and Objectives: Importance of development of novel probiotic fermented milk and challenge made for its acceptability is well known. In this research, the impact of different inoculation sizes of yogurt and DL-type starter culture (mesophilic and thermophilic LAB on titratable acidity, viscosity, sensorial and microbial properties of fermented milk was investigated; and finally, probiotic Langfil was produced.Materials and Methods: Fermented milk produced by 1, 2 and 3% v v-1 inocula consisting thermophilic: mesophilic starter cultures 10:90 (Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. lactis biovar. diacetylactis and Leuconostoc mesenteroides subsp. cremoris. Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus were analyzed for determination of titratable acidity, viscosity, viability of mesophilic starter cultures and sensory properties on days 5, 10, and 15 of storage at 4°C. Then, the most suitable treatments were selected for the producing probiotic Langfil, containing probiotic starter culture (2% v v-1 inoculums with equal ratio of Lactobacillus acidophilus and Bifidobacterium bifidum. Lactococcus lactis and L. cremoris were counted on M17 agar, while Leuconostoc and Lactobacillus were counted aerobically on tomato juice agar and MRS bile agar, respectively. Bifidobacterium was cultured anaerobically on MRS bile agar. Sensory evaluation was carried out by ten trained panelists, based on a nine-point hedonic scale during the cold storage.Results and Conclusion: According to results, the best organoleptic properties were achieved in the product prepared with 2% the mesophilic and thermophilic starter cultures and 2% probiotic. This product had a high viscosity. An Iranian probiotic Langfil with desired properties was produced using the best treatment prepared.Conflict of interests: The authors declare no conflict of

Microbiological analysis of coliforms and mesophilic aerobic spore formers in gamma irradiated cocoa beans (Theobroma cacao L.)

International Nuclear Information System (INIS)

Barata, Anderson Demetrio; Mansur Netto, Elias

1995-01-01

The presence of coliforms in processed foods is an useful indicator of post-sanitization and post processing contamination, and members of the mesophilic aerobic spore formers have great importance in food spoilage. Spore - forming aerobic bacilli have been observed in fermenting cocoa in Jamaica and West Africa. The results of this work has shown a considerable reduction of the mesophilic aerobic spore formers in irradiated Brazilian Comun Cocoa beans as long as the irradiation dose was increased from 1.05 to 3.99 kGy. The presence of coliforms irradiated has not been found even in the coroa beans with the dose of 1.05 kGy. (author). 4 refs., 1 tab

THAWING PROCEDURES FOR HOSPITAL-MADE ENTERAL FEEDINGS: SURVIVAL OF COLIFORM AND MESOPHILIC AEROBIC BACTERIA

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KATHIA ROSSI ROLIM LOPES

2009-07-01

Full Text Available

ABSTRACT: This study had the purpose to observe the effect of thawing procedures on survival of coliform and mesophilic aerobic bacteria in hospital-made enteral feedings. The samples are represented by three different lots. The tests were realized in three moments: immediately after the sample preparation and after freezing during 1 or 2 months. The thawing procedures were denominated convencional and alternative. The first, used by hospital, utilizes water bath at 50ºC, considering the time spent from the total thawing to its distribution in the infirmaries. The second was the fast thawing made by microwaving. The results showed that the reduction of the mesophiles and coliform was related to the time the samples were frozen. The results obtained indicate an advantage of the alternative method, which presented lower total and fecal coliform counts than the conventional one. KEYWORDS: Enteral feedings; thawing; food microbiology.

A novel process for volatile fatty acids production from syngas by integrating with mesophilic alkaline fermentation of waste activated sludge

DEFF Research Database (Denmark)

Rao, Yue; Wan, Jingjing; Liu, Yafeng

2018-01-01

The present study proposed and demonstrated a novel process for the bioconversion of syngas (mainly CO and H2) to valuable volatile fatty acids (VFA) by integrating with mesophilic alkaline fermentation of waste activated sludge (WAS). The results showed that although pH 9 was suitable for VFA...... to the mesophilic alkaline fermentation of WAS at pH 10 not only resulted in the enrichment of some known bacteria related with syngas conversion, but also changed the microbial community compositions for the fermentation of WAS....

Performance of mesophilic anaerobic granules for removal of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) from aqueous solution

International Nuclear Information System (INIS)

An Chunjiang; He Yanling; Huang Guohe; Liu Yonghong

2010-01-01

The performance of mesophilic anaerobic granules to degrade octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was investigated under various conditions. The results of batch experiments showed that anaerobic granules were capable of removing HMX from aqueous solution with high efficiency. Both biotic and abiotic mechanisms contributed to the removal of HMX by anaerobic granules under mesophilic conditions. Adsorption appeared to play a significant role in the abiotic process. Furthermore, HMX could be biodegraded by anaerobic granules as the sole substrate. After 16 days of incubation, 99.04% and 96.42% of total HMX could be removed by 1 g VSS/L acclimated and unacclimated granules, respectively. Vancomycin, an inhibitor of acetogenic bacteria, caused a significant inhibition of HMX biotransformation, while 2-bromoethanesulfonic acid, an inhibitor of methanogenic bacteria, only resulted in a slight decrease of metabolic activity. The presence of the glucose, as a suitable electron donor and carbon source, was found to enhance the degradation of HMX by anaerobic granules. Our study showed that sulfate had little adverse effects on biotransformation of HMX by anaerobic granules. However, nitrate had significant inhibitory effect on the extent of HMX removal especially in the initial period. This study offered good prospects of using high-rate anaerobic technology in the treatment of munition wastewater.

Mesophilic and psychrotrophic bacteria from meat and their spoilage potential in vitro and in beef.

Science.gov (United States)

Ercolini, Danilo; Russo, Federica; Nasi, Antonella; Ferranti, Pasquale; Villani, Francesco

2009-04-01

Mesophilic and psychrotrophic populations from refrigerated meat were identified in this study, and the spoilage potential of microbial isolates in packaged beef was evaluated by analyzing the release of volatile organic compounds (VOC) by gas chromatography-mass spectrometry (GC/MS). Fifty mesophilic and twenty-nine psychrotrophic isolates were analyzed by random amplified polymorphic DNA-PCR, and representative strains were identified by 16S rRNA gene sequencing. Carnobacterium maltaromaticum and C. divergens were the species most frequently found in both mesophilic and psychrotrophic populations. Acinetobacter baumannii, Buttiauxella spp. and Serratia spp. were identified among the mesophilic isolates, while Pseudomonas spp. were commonly identified among the psychrotrophs. The isolates were further characterized for their growth at different temperatures and their proteolytic activity in vitro on meat proteins extracts at 7 degrees C. Selected proteolytic strains of Serratia proteamaculans, Pseudomonas fragi, and C. maltaromaticum were used to examine their spoilage potential in situ. Single strains of these species and mixtures of these strains were used to contaminate beef chops that were packed and stored at 7 degrees C. At time intervals up to 1 month, viable counts were determined, and VOC were identified by GC/MS. Generally, the VOC concentrations went to increase during the storage of the contaminated meats, and the profiles of the analyzed meat changed dramatically depending on the contaminating microbial species. About 100 volatiles were identified in the different contaminated samples. Among the detected volatiles, some specific molecules were identified only when the meat was contaminated by a specific microbial species. Compounds such as 2-ethyl-1-hexanol, 2-buten-1-ol, 2-hexyl-1-octanol, 2-nonanone, and 2-ethylhexanal were detectable only for C. maltaromaticum, which also produced the highest number of aldehydes, lactones, and sulfur compounds. The

Effect of high pressure on mesophilic lactic fermentation streptococci

Energy Technology Data Exchange (ETDEWEB)

Reps, A; Kuzmicka, M; Wisniewska, K [Chair of Food Biotechnology, University of Warmia and Mazury, ul. Heweliusza 1, 10-724 Olsztyn (Poland)], E-mail: arnold.reps@uwm.edu.pl

2008-07-15

The research concerned the effect of high pressure on mesophilic lactic fermentation streptococci, present in two cheese-making commercial inocula produced by Christian-Hansen. Water solutions of inocula were pressurized at 50-800 MPa, at room temperature, for 30-120 min. Pressurization at 50-100 MPa slightly increased or reduced the number of lactic streptococci, depending on the inoculum and pressurization time. Pressurization at 200 MPa caused a reduction in the number of streptococci by over 99.9%, whereas the pressure of 400 MPa and above almost completely inactivated streptococci. Pressurization also reduced the dynamics of microorganism growth and acidification, to the degree depending on the pressure.

Interspecies Electron Transfer during Propionate and Butyrate Degradation in Mesophilic, Granular Sludge

OpenAIRE

Schmidt, J. E.; Ahring, B. K.

1995-01-01

Granules from a mesophilic upflow anaerobic sludge blanket reactor were disintegrated, and bacteria utilizing only hydrogen or formate or both hydrogen and formate were added to investigate the role of interspecies electron transfer during degradation of propionate and butyrate. The data indicate that the major electron transfer occurred via interspecies hydrogen transfer, while interspecies formate transfer may not be essential for interspecies electron transfer in this system during degrada...

Mesophilic and thermophilic alkaline fermentation of waste activated sludge for hydrogen production: Focusing on homoacetogenesis

DEFF Research Database (Denmark)

Wan, Jingjing; Jing, Yuhang; Zhang, Shicheng

2016-01-01

The present study compared the mesophilic and thermophilic alkaline fermentation of waste activated sludge (WAS) for hydrogen production with focus on homoacetogenesis, which mediated the consumption of H2 and CO2 for acetate production. Batch experiments showed that hydrogen yield of WAS increased...

Comprehensive microbial analysis of combined mesophilic anaerobic-thermophilic aerobic process treating high-strength food wastewater

DEFF Research Database (Denmark)

Jang, Hyun Min; Ha, Jeong Hyub; Park, Jong Moon

2015-01-01

of phylum Actinobacteria in both R1 and R2, and a predominance of phyla Synergistetes and Firmicutes in R3 during Run II. Furthermore, R1 and R2 shared genera (Prevotella, Aminobacterium, Geobacillus and Unclassified Actinobacteria), which suggests synergy between mesophilic anaerobic digestion...

Temperature-Dependent Alkyl Glycerol Ether Lipid Composition of Mesophilic and Thermophilic Sulfate-Reducing Bacteria

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Arnauld Vinçon-Laugier

2017-08-01

Full Text Available The occurrence of non-isoprenoid alkyl glycerol ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid content of two mesophilic (Desulfatibacillum aliphaticivorans and Desulfatibacillum alkenivorans and one thermophilic (Thermodesulfobacterium commune sulfate-reducing bacteria—whose membranes are mostly composed of ether lipids—was investigated as a function of growth temperature (20–40°C and 54–84°C, respectively. For all strains, the cellular lipid content was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl glycerols, monoalkyl glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-2 vs sn-1 monoalkyl glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong

Chronic impacts of oxytetracycline on mesophilic anaerobic digestion of excess sludge: Inhibition of hydrolytic acidification and enrichment of antibiotic resistome.

Science.gov (United States)

Tian, Zhe; Zhang, Yu; Yang, Min

2018-07-01

We evaluated the chronic impact of oxytetracycline (OTC) on performance and antibiotic resistance development during the mesophilic anaerobic digestion (AD) of antibiotic-containing biomass. Mesophilic AD was conducted in a completely stirred tank reactor by constantly feeding municipal excess sludge spiked with increasing concentrations of OTC (0-1000 mg L -1 ) under a solid retention time of 20 days over a period of 265 days. Results showed that methane generation of mesophilic AD was inhibited when the OTC concentration in digested sludge was increased to around 18,000 mg kg -1 (OTC dose, 1000 mg L -1 ), due to the inhibition of fermenting and acidogenic bacteria. Metagenomic sequencing and high-throughput quantitative PCR analysis demonstrated that tetracycline resistance genes were the most dominant type (38.47-43.76%) in the resistome, with tetG, tetX, tetM, tetR, tetQ, tetO, and tetL as the dominant resistant subtypes throughout the whole experimental period. The relative abundance of these tet genes increased from 2.10 × 10 -1 before spiking OTC (OTC concentration in digested sludge, 8.97 mg kg -1 ) to 2.83 × 10 -1 (p resistome variation were 29.35% and 21.51%, respectively. Thus, considering the inhibition of hydrolytic acidification and enrichment of antibiotic resistome, mesophilic AD is not suggested to directly treat the biomass containing OTC concentration higher than 200 mg L -1 . Copyright © 2018 Elsevier Ltd. All rights reserved.

[Distribution and removal of anaerobic antibiotic resistant bacteria during mesophilic anaerobic digestion of sewage sludge].

Science.gov (United States)

Tong, Juan; Wang, Yuan-Yue; Wei Yuan, Song

2014-10-01

Sewage sludge is one of the major sources that releasing antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) into the environment since it contains large amount of ARB, but there is little information about the fate of the anaerobic ARB in the anaerobic digestion of sewage sludge. Therefore, the distribution, removal and seasonal changes of tetracycline and β-lactam antibiotics resistant bacteria in the mesophilic egg-shaped digesters of a municipal wastewater treatment plant were investigated for one year in this study. Results showed that there were higher amounts of ARB and higher resistance rate of β-lactam antibiotics than that of tetracycline antibiotics in the sewage sludge. All ARB could be significantly reduced during the mesophilic anaerobic digestion process by 1.48-1.64 log unit (P anaerobic digestion by 12.0% and 14.3%, respectively (P bacteria, there were more ARB in the sewage sludge in cold season than in warm season (P < 0.05).

Thermo-resistance Acquisition of A Mesophilic Bacterium with The Aid of Vector Particles Originating from Thermophiles

Science.gov (United States)

Sugitate, T.; Inaba, N.; Kurusu, Y.; Hoaki, T.; Chiura, H. X.

2004-12-01

The present study was aimed to examine whether virus-like particles (VLPs) would be able to transfer and express the thermo-resistance gene of thermophilic microbes in the mesophilic auxotrophic Escherichia coli AB1157 mutant. A hyper-thermophilic archaea, Thermococcus kodakaraensis B41, that was isolated from the Suiyo Seamount APSK06 boring core, released particles (KD-VLPs) during culture. Transduction towards recipient E. coli AB1157 was carried out using KD-VLP as the gene transfer mediator, in order to examine the lethal effect and thermo-resistant gene transfer capability of the particle. The colony forming ability of the cells was examined in 7 % of gelrite supplemented-LB plates (LB-gelrite plates) at 50, 56, and 70 ° C. Regardless of UV irradiation, KD-VLP showed a reduced efficiency of plating (EOP) of recipient viable cell population to ca 65 %. Four colonies were formed in LB-gelrite plates at 50 ° C, which were named as KD-E-Trans, and the gene transfer frequency was estimated to be 5.12 × 10-8 cfu/particle. Obtained KD-E-Trans was cultured in LB liquid medium employing the same high temperature conditions. The cells grew 1.6 ˜ 6 fold of the inocula in 13 days at all the examined temperatures, and the generation time of the transductants were as follows: ca 28 hours at 50 ° C, ca 73 hours at 56 ° C, ca 266 hours at 70 ° C. Thus, the gene transfer of thermo-resistance to mesophilic E. coli from another Domain with the aid of KD-VLPs was demonstrated.

Functional annotation of the mesophilic-like character of mutants in a cold-adapted enzyme by self-organising map analysis of their molecular dynamics.

Science.gov (United States)

Fraccalvieri, Domenico; Tiberti, Matteo; Pandini, Alessandro; Bonati, Laura; Papaleo, Elena

2012-10-01

Multiple comparison of the Molecular Dynamics (MD) trajectories of mutants in a cold-adapted α-amylase (AHA) could be used to elucidate functional features required to restore mesophilic-like activity. Unfortunately it is challenging to identify the different dynamic behaviors and correctly relate them to functional activity by routine analysis. We here employed a previously developed and robust two-stage approach that combines Self-Organising Maps (SOMs) and hierarchical clustering to compare conformational ensembles of proteins. Moreover, we designed a novel strategy to identify the specific mutations that more efficiently convert the dynamic signature of the psychrophilic enzyme (AHA) to that of the mesophilic counterpart (PPA). The SOM trained on AHA and its variants was used to classify a PPA MD ensemble and successfully highlighted the relationships between the flexibilities of the target enzyme and of the different mutants. Moreover the local features of the mutants that mostly influence their global flexibility in a mesophilic-like direction were detected. It turns out that mutations of the cold-adapted enzyme to hydrophobic and aromatic residues are the most effective in restoring the PPA dynamic features and could guide the design of more mesophilic-like mutants. In conclusion, our strategy can efficiently extract specific dynamic signatures related to function from multiple comparisons of MD conformational ensembles. Therefore, it can be a promising tool for protein engineering.

DIAGNOSIS OF EGG MARKETING CONDITION IN SINOP - MT

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M. Ribeiro

2015-10-01

Full Text Available The eggs, when manipulated in inadequate sanitary conditions, are considered as ways for development and multiplication of spoilage and pathogenic microorganisms. Thus, the objective was to evaluate the microbiological quality of eggs marketed out at Sinop – MT, through the identification of Salmonella spp., count of aerobic mesophile bacteria and enterobacteria. We collected 12 eggs from each establishment, three supermarkets and three fairs. Were not identified Salmonella spp. in egg shells and internal content. Escherichia coli was isolated from the internal contents of eggs come from an street fair. In aerobic mesophilic counts were obtained from eggs supermarkets counts CFU/g/egg shell of 5,8 x 105, 1,21 x 105 e 4,7 x 103. In relation to the fairs, the counts were 7,2 x 104, 5,66 x 104 e 8,7 x 103. The absence of Salmonella spp. the evaluated eggs classifies them as fit for consumption for compliance with current legislation. However, the presence of E. coli and the values of aerobic mesophilic counts and Enterobacteriaceae highlight the need to establish measures to reduce bacterial contamination of shell eggs sold out at Sinop, MT.

Genome Sequence of Leuconostoc mesenteroides subsp. cremoris Strain T26, Isolated from Mesophilic Undefined Cheese Starter.

Science.gov (United States)

Pedersen, T B; Kot, W P; Hansen, L H; Sørensen, S J; Broadbent, J R; Vogensen, F K; Ardö, Y

2014-06-05

Leuconostoc is the main group of heterofermentative bacteria found in mesophilic dairy starters. They grow in close symbiosis with the Lactococcus population and are able to degrade citrate. Here we present a draft genome sequence of Leuconostoc mesenteroides subsp. cremoris strain T26. Copyright © 2014 Pedersen et al.

Continuous dark fermentative hydrogen production by mesophilic microflora: Principles and progress

Energy Technology Data Exchange (ETDEWEB)

Hawkes, Freda R.; Hussy, Ines; Kyazze, Godfrey; Dinsdale, Richard; Hawkes, Dennis L. [School of Applied Sciences, University of Glamorgan, Pontypridd RCT CF37 1DL (United Kingdom)

2007-02-15

Continuous, dark fermentative hydrogen production technology using mixed microflora at mesophilic temperatures may be suitable for commercial development. Clostridial-based cultures from natural sources have been widely used, but more information on the need for heat treatment of inocula and conditions leading to germination and sporulation are required. The amount of nutrients given in the literature vary widely. Hydrogen production is reported to proceed without methane production in the reactor in the pH range 4.5-6.7, with hydraulic retention times optimally between a few hours and 3 days depending on substrate. Higher substrate concentrations should be more energy-efficient but there are product inhibition limitations, for example from unionised butyric acid. Inhibition by H{sub 2} can be reduced by stirring, sparging or extraction through membranes. Of the reactor types investigated, while granules have the best performance with soluble substrate, for particulate feedstock biofilm reactors or continuous stirred tank reactors may be most successful. A second stage is required to utilise the fermentation end products which, when cost-effective reactors are developed, may be photofermentation or microbial fuel cell technologies. Anaerobic digestion is a currently-available technology and the two-stage process is reported to give greater conversion efficiency than anaerobic digestion alone. (author)

Effects of triclosan, diclofenac, and nonylphenol on mesophilic and thermophilic methanogenic activity and on the methanogenic communities

DEFF Research Database (Denmark)

Symsaris, Evangelos C.; Fotidis, Ioannis; Stasinakis, Athanasios S.

2015-01-01

In this study, a toxicity assay using a mesophilic wastewater treatment plant sludge-based (SI) and a thermophilic manure-based inoculum (MI), under different biomass concentrations was performed to define the effects of diclofenac (DCF), triclosan (TCS), and nonylphenol (NP) on anaerobic digestion...

Mesophilic and thermophilic anaerobic co-digestion of winery wastewater sludge and wine lees: An integrated approach for sustainable wine production.

Science.gov (United States)

Da Ros, C; Cavinato, C; Pavan, P; Bolzonella, D

2017-12-01

In this work, winery wastes generated by a cellar producing approximately 300,000 hL of wine per year was monitored for a period of one year. On average, 196 L of wastewater, 0.1 kg of waste activated sludge (dry matter) and 1.6 kg of wine lees were produced per hectoliter of wine produced. Different winery wastes, deriving from different production steps, namely waste activated sludge from wastewater treatment and wine lees, were co-treated using an anaerobic digestion process. Testing was conducted on a pilot scale for both mesophilic and thermophilic conditions. The process was stable for a long period at 37 °C, with an average biogas production of 0.386 m 3 /kg COD fed . On the other hand, for thermophilic conditions, volatile fatty acids accumulated in the reactor and the process failed after one hydraulic retention time (23 days). In order to fix the biological process, trace elements (iron, cobalt and nickel) were added to the feed of the thermophilic reactor. Metals augmentation improved process stability and yields at 55 °C. The pH ranged between 7.8 and 8.0, and specific gas production was 0.450 m 3 /kg COD fed , which corresponded to dry matter and COD removals of 34% and 88%, respectively. Although the observed performances in terms of biogas production were good, the thermophilic process exhibited some limitations related to both the necessity of metals addition and the worse dewaterability properties. In fact, while the mesophilic digestates reached a good dewatering quality via the addition of 6.5 g of polymer per kg of dry matter, the required dosage for the thermophilic sludge was greater than 10 g/kg of dry matter. Copyright © 2016 Elsevier Ltd. All rights reserved.

Diversity, Localization, and Physiological Properties of Filamentous Microbes Belonging to Chloroflexi Subphylum I in Mesophilic and Thermophilic Methanogenic Sludge Granules

Science.gov (United States)

Yamada, Takeshi; Sekiguchi, Yuji; Imachi, Hiroyuki; Kamagata, Yoichi; Ohashi, Akiyoshi; Harada, Hideki

2005-01-01

We previously reported that the thermophilic filamentous anaerobe Anaerolinea thermophila, which is the first cultured representative of subphylum I of the bacterial phylum Chloroflexi, not only was one of the predominant constituents of thermophilic sludge granules but also was a causative agent of filamentous sludge bulking in a thermophilic (55°C) upflow anaerobic sludge blanket (UASB) reactor in which high-strength organic wastewater was treated (Y. Sekiguchi, H. Takahashi, Y. Kamagata, A. Ohashi, and H. Harada, Appl. Environ. Microbiol. 67:5740-5749, 2001). To further elucidate the ecology and function of Anaerolinea-type filamentous microbes in UASB sludge granules, we surveyed the diversity, distribution, and physiological properties of Chloroflexi subphylum I microbes residing in UASB granules. Five different types of mesophilic and thermophilic UASB sludge were used to analyze the Chloroflexi subphylum I populations. 16S rRNA gene cloning-based analyses using a 16S rRNA gene-targeted Chloroflexi-specific PCR primer set revealed that all clonal sequences were affiliated with the Chloroflexi subphylum I group and that a number of different phylotypes were present in each clone library, suggesting the ubiquity and vast genetic diversity of these populations in UASB sludge granules. Subsequent fluorescence in situ hybridization (FISH) of the three different types of mesophilic sludge granules using a Chloroflexi-specific probe suggested that all probe-reactive cells had a filamentous morphology and were widely distributed within the sludge granules. The FISH observations also indicated that the Chloroflexi subphylum I bacteria were not always the predominant populations within mesophilic sludge granules, in contrast to thermophilic sludge granules. We isolated two mesophilic strains and one thermophilic strain belonging to the Chloroflexi subphylum I group. The physiological properties of these isolates suggested that these populations may contribute to the

Life at extreme conditions: neutron scattering studies of biological molecules suggest that evolution selected dynamics

International Nuclear Information System (INIS)

Zaccai, Joseph Giuseppe

2008-01-01

The short review concentrates on recent work performed at the neutrons in biology laboratories of the Institut Laue Langevin and Institut de Biologie Structurale in Grenoble. Extremophile organisms have been discovered that require extreme conditions of temperature, pressure or solvent environment for survival. The existence of such organisms poses a significant challenge in understanding the physical chemistry of their proteins, in view of the great sensitivity of protein structure and stability to the aqueous environment and to external conditions in general. Results of neutron scattering measurements on the dynamics of proteins from extremophile organisms, in vitro as well as in vivo, indicated remarkably how adaptation to extreme conditions involves forces and fluctuation amplitudes that have been selected specifically, suggesting that evolutionary macromolecular selection proceeded via dynamics. The experiments were performed on a halophilic protein, and membrane adapted to high salt, a thermophilic enzyme adapted to high temperature and its mesophilic (adapted to 37 degC) homologue; and in vivo for psychrophilic, mesophilic, thermophilic and hyperthermophilic bacteria, adapted respectively to temperatures of 4 degC, 37 degC, 75 degC and 85 degC. Further work demonstrated the existence of a water component of exceptionally low mobility in an extreme halophile from the Dead Sea, which is not present in mesophile bacterial cells. (author)

Total mesophilic counts underestimate in many cases the contamination levels of psychrotrophic lactic acid bacteria (LAB) in chilled-stored food products at the end of their shelf-life.

Science.gov (United States)

Pothakos, Vasileios; Samapundo, Simbarashe; Devlieghere, Frank

2012-12-01

The major objective of this study was to determine the role of psychrotrophic lactic acid bacteria (LAB) in spoilage-associated phenomena at the end of the shelf-life of 86 various packaged (air, vacuum, modified-atmosphere) chilled-stored retail food products. The current microbiological standards, which are largely based on the total viable mesophilic counts lack discriminatory capacity to detect psychrotrophic LAB. A comparison between the total viable counts on plates incubated at 30 °C (representing the mesophiles) and at 22 °C (indicating the psychrotrophs) for 86 food samples covering a wide range - ready-to-eat vegetable salads, fresh raw meat, cooked meat products and composite food - showed that a consistent underestimation of the microbial load occurs when the total aerobic mesophilic counts are used as a shelf-life parameter. In 38% of the samples, the psychrotrophic counts had significantly higher values (+0.5-3 log CFU/g) than the corresponding total aerobic mesophilic counts. A total of 154 lactic acid bacteria, which were unable to proliferate at 30 °C were isolated. In addition, a further 43 with a poor recovery at this temperature were also isolated. This study highlights the potential fallacy of the total aerobic mesophilic count as a reference shelf-life parameter for chilled food products as it can often underestimate the contamination levels at the end of the shelf-life. Copyright © 2012 Elsevier Ltd. All rights reserved.

Protein dynamics and stability: The distribution of atomic fluctuations in thermophilic and mesophilic dihydrofolate reductase derived using elastic incoherent neutron scattering

International Nuclear Information System (INIS)

Meinhold, Lars; Clement, David; Tehei, M.; Daniel, R.M.; Finney, J.L.; Smith, Jeremy C.

2008-01-01

The temperature dependence of the dynamics of mesophilic and thermophilic dihydrofolate reductase is examined using elastic incoherent neutron scattering. It is demonstrated that the distribution of atomic displacement amplitudes can be derived from the elastic scattering data by assuming a (Weibull) functional form that resembles distributions seen in molecular dynamics simulations. The thermophilic enzyme has a significantly broader distribution than its mesophilic counterpart. Furthermore, although the rate of increase with temperature of the atomic mean-square displacements extracted from the dynamic structure factor is found to be comparable for both enzymes, the amplitudes are found to be slightly larger for the thermophilic enzyme. Therefore, these results imply that the thermophilic enzyme is the more flexible of the two

Mesophilic and hyperthermophilic adenylate kinases differ in their tolerance to random fragmentation.

Science.gov (United States)

Segall-Shapiro, Thomas H; Nguyen, Peter Q; Dos Santos, Edgardo D; Subedi, Saurav; Judd, Justin; Suh, Junghae; Silberg, Jonathan J

2011-02-11

The extent to which thermostability influences the location of protein fragmentation sites that allow retention of function is not known. To evaluate this, we used a novel transposase-based approach to create libraries of vectors that express structurally-related fragments of Bacillus subtilis adenylate kinase (BsAK) and Thermotoga neapolitana adenylate kinase (TnAK) with identical modifications at their termini, and we selected for variants in each library that complement the growth of Escherichia coli with a temperature-sensitive adenylate kinase (AK). Mutants created using the hyperthermophilic TnAK were found to support growth with a higher frequency (44%) than those generated from the mesophilic BsAK (6%), and selected TnAK mutants complemented E. coli growth more strongly than homologous BsAK variants. Sequencing of functional clones from each library also identified a greater dispersion of fragmentation sites within TnAK. Nondisruptive fission sites were observed within the AMP binding and core domains of both AK homologs. However, only TnAK contained sites within the lid domain, which undergoes dynamic fluctuations that are critical for catalysis. These findings implicate the flexible lid domain as having an increased sensitivity to fission events at physiological temperatures. In addition, they provide evidence that comparisons of nondisruptive fission sites in homologous proteins could be useful for finding dynamic regions whose conformational fluctuations are important for function, and they show that the discovery of protein fragments that cooperatively function in mesophiles can be aided by the use of thermophilic enzymes as starting points for protein design. Copyright © 2010 Elsevier Ltd. All rights reserved.

Mesophilic leaching of copper sulphide sludge

Directory of Open Access Journals (Sweden)

VLADIMIR B. CVETKOVSKI

2009-02-01

Full Text Available Copper was precipitated using a sodium sulphide solution as the precipitation agent from an acid solution containing 17 g/l copper and 350 g/l sulphuric acid. The particle size of nearly 1 µm in the sulphide sludge sample was detected by optical microscopy. Based on chemical and X-ray diffraction analyses, covellite was detected as the major sulphide mineral. The batch bioleach amenability test was performed at 32 °C on the Tk31 mine mesophilic mixed culture using a residence time of 28 days. The dissolution of copper sulphide by direct catalytic leaching of the sulphides with bacteria attached to the particles was found to be worthy, although a small quantity of ferrous ions had to be added to raise the activity of the bacteria and the redox potential of the culture medium. Throughout the 22-day period of the bioleach test, copper recovery based on residue analysis indicated a copper extraction of 95 %, with copper concentration in the bioleach solution of 15 g/l. The slope of the straight line tangential to the exponential part of the extraction curve gave a copper solubilisation rate of 1.1 g/l per day. This suggests that a copper extraction of 95 % for the period of bioleach test of 13.6 days may be attained in a three-stage bioreactor system.

Thermo- and mesophilic aerobic batch biodegradation of high-strength distillery wastewater (potato stillage)--utilisation of main carbon sources.

Science.gov (United States)

Krzywonos, Małgorzata; Cibis, Edmund; Lasik, Małgorzata; Nowak, Jacek; Miśkiewicz, Tadeusz

2009-05-01

The aim of the study was to ascertain the extent to which temperature influences the utilisation of main carbon sources (reducing substances determined before and after hydrolysis, glycerol and organic acids) by a mixed culture of thermo- and mesophilic bacteria of the genus Bacillus in the course of aerobic batch biodegradation of potato stillage, a high-strength distillery effluent (COD=51.88 g O(2)/l). The experiments were performed at 20, 30, 35, 40, 45, 50, 55, 60 and 63 degrees C, at pH 7, in a 5l working volume stirred-tank bioreactor (Biostat B, B. Braun Biotech International) with a stirrer speed of 550 rpm and aeration at 1.6 vvm. Particular consideration was given to the following issues: (1) the sequence in which the main carbon sources in the stillage were assimilated and (2) the extent of their assimilation achieved under these conditions.

Investigation of the bacteriophage community in induced lysates of undefined mesophilic mixed-strain DL-cultures using classical and metagenomic approaches

DEFF Research Database (Denmark)

Muhammed, Musemma K.; Olsen, Mette L.; Kot, Witold

2018-01-01

To investigate the notion that starter cultures can be a reservoir of bacteriophages (phages) in the dairy environment, strains of three DL-starters (undefined mesophilic mixed-strain starters containing Lactococcus lactis subsp. lactis biovar. diacetylactis and Leuconostoc species) were selected...

Structural prediction and comparative docking studies of psychrophilic β- Galactosidase with lactose, ONPG and PNPG against its counter parts of mesophilic and thermophilic enzymes.

Science.gov (United States)

Kumar, Ponnada Suresh; Pulicherla, Kk; Ghosh, Mrinmoy; Kumar, Anmol; Rao, Krs Sambasiva

2011-01-01

Enzymes from psychrophiles catalyze the reactions at low temperatures with higher specific activity. Among all the psychrophilic enzymes produced, cold active β-galactosidase from marine psychrophiles revalorizes a new arena in numerous areas at industrial level. The hydrolysis of lactose in to glucose and galactose by cold active β-galactosidase offers a new promising approach in removal of lactose from milk to overcome the problem of lactose intolerance. Herein we propose, a 3D structure of cold active β-galactosidase enzyme sourced from Pseudoalteromonas haloplanktis by using Modeler 9v8 and best model was developed having 88% of favourable region in ramachandran plot. Modelling was followed by docking studies with the help of Auto dock 4.0 against the three substrates lactose, ONPG and PNPG. In addition, comparative docking studies were also performed for the 3D model of psychrophilic β-galactosidase with mesophilic and thermophilic enzymes. Docking studies revealed that binding affinity of enzyme towards the three different substrates is more for psychrophilic enzyme when compared with mesophilic and thermophilic enzymes. It indicates that the enzyme has high specific activity at low temperature when compared with mesophilic and thermophilic enzymes.

Synergetic effect of pH and biochemical components on bacterial diversity during mesophilic anaerobic fermentation of biomass-origin waste.

Science.gov (United States)

Lü, F; Shao, L M; Bru, V; Godon, J J; He, P J

2009-02-01

To investigate the synergetic effect of pH and biochemical components on bacterial community structure during mesophilic anaerobic degradation of solid wastes with different origins, and under acidic or neutral conditions. The bacterial community in 16 samples of solid wastes with different biochemical compositions and origins was evaluated during mesophilic anaerobic degradation at acidic and neutral pH. Denaturing gradient gel electrophoresis (DGGE) and single-strand conformation polymorphism (SSCP) were used to compare the communities. Multivariate analysis of the DGGE and SSCP results revealed that most of the dominant microbes were dependent on the content of easily degradable carbohydrates in the samples. Furthermore, the dominant microbes were divided into two types, those that preferred an acid environment and those that preferred a neutral environment. A shift in pH was found to change their preference for medium substrates. Although most of the substrates with similar origin and biochemical composition had similar microbial diversity during fermentation, some microbes were found only in substrates with specific origins. For example, two microbes were only found in substrate that contained lignocellulose and animal protein without starch. These microbes were related to micro-organisms that are found in swine manure, as well as in other intestinal or oral niches. In addition, the distribution of fermentation products was less sensitive to the changes in pH and biochemical components than the microbial community. Bacterial diversity during anaerobic degradation of organic wastes was affected by both pH and biochemical components; however, pH exerted a greater effect. The results of this study reveal that control of pH may be an effective method to produce a stable bacterial community and relatively similar product distribution during anaerobic digestion of waste, regardless of variation in the waste feedstocks.

Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

Directory of Open Access Journals (Sweden)

Jing Yi

Full Text Available The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies.

Effect of Increasing Total Solids Contents on Anaerobic Digestion of Food Waste under Mesophilic Conditions: Performance and Microbial Characteristics Analysis

Science.gov (United States)

Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies. PMID:25051352

Effect of increasing total solids contents on anaerobic digestion of food waste under mesophilic conditions: performance and microbial characteristics analysis.

Science.gov (United States)

Yi, Jing; Dong, Bin; Jin, Jingwei; Dai, Xiaohu

2014-01-01

The total solids content of feedstocks affects the performances of anaerobic digestion and the change of total solids content will lead the change of microbial morphology in systems. In order to increase the efficiency of anaerobic digestion, it is necessary to understand the role of the total solids content on the behavior of the microbial communities involved in anaerobic digestion of organic matter from wet to dry technology. The performances of mesophilic anaerobic digestion of food waste with different total solids contents from 5% to 20% were compared and the microbial communities in reactors were investigated using 454 pyrosequencing technology. Three stable anaerobic digestion processes were achieved for food waste biodegradation and methane generation. Better performances mainly including volatile solids reduction and methane yield were obtained in the reactors with higher total solids content. Pyrosequencing results revealed significant shifts in bacterial community with increasing total solids contents. The proportion of phylum Chloroflexi decreased obviously with increasing total solids contents while other functional bacteria showed increasing trend. Methanosarcina absolutely dominated in archaeal communities in three reactors and the relative abundance of this group showed increasing trend with increasing total solids contents. These results revealed the effects of the total solids content on the performance parameters and the behavior of the microbial communities involved in the anaerobic digestion of food waste from wet to dry technologies.

Sustainable organic loading rate and energy recovery potential of mesophilic anaerobic membrane bioreactor for municipal wastewater treatment

KAUST Repository

Wei, Chunhai

2014-08-01

The overall performance of a mesophilic anaerobic membrane bioreactor (AnMBR) for synthetic municipal wastewater treatment was investigated under a range of organic loading rate (OLR). A very steady and high chemical oxygen demand (COD) removal (around 98%) was achieved over a broad range of volumetric OLR of 0.8-10gCOD/L/d. The sustainable volumetric and sludge OLR satisfying a permeate COD below 50mg/L for general reuse was 6gCOD/L/d and 0.63gCOD/gMLVSS (mixed liquor volatile suspended solids)/d, respectively. At a high sludge OLR of over 0.6gCOD/gMLVSS/d, the AnMBR achieved high methane production of over 300ml/gCOD (even approaching the theoretical value of 382ml/gCOD). A low biomass production of 0.015-0.026gMLVSS/gCOD and a sustainable flux of 6L/m2/h were observed. The integration of a heat pump and forward osmosis into the mesophilic AnMBR process would be a promising way for net energy recovery from typical municipal wastewater in a temperate area. © 2014 Elsevier Ltd.

Sustainable organic loading rate and energy recovery potential of mesophilic anaerobic membrane bioreactor for municipal wastewater treatment

KAUST Repository

Wei, Chunhai; Harb, Moustapha; Amy, Gary L.; Hong, Pei-Ying; Leiknes, TorOve

2014-01-01

The overall performance of a mesophilic anaerobic membrane bioreactor (AnMBR) for synthetic municipal wastewater treatment was investigated under a range of organic loading rate (OLR). A very steady and high chemical oxygen demand (COD) removal (around 98%) was achieved over a broad range of volumetric OLR of 0.8-10gCOD/L/d. The sustainable volumetric and sludge OLR satisfying a permeate COD below 50mg/L for general reuse was 6gCOD/L/d and 0.63gCOD/gMLVSS (mixed liquor volatile suspended solids)/d, respectively. At a high sludge OLR of over 0.6gCOD/gMLVSS/d, the AnMBR achieved high methane production of over 300ml/gCOD (even approaching the theoretical value of 382ml/gCOD). A low biomass production of 0.015-0.026gMLVSS/gCOD and a sustainable flux of 6L/m2/h were observed. The integration of a heat pump and forward osmosis into the mesophilic AnMBR process would be a promising way for net energy recovery from typical municipal wastewater in a temperate area. © 2014 Elsevier Ltd.

Effect of hemicellulolytic enzymes on mesophilic methane fermentation

Energy Technology Data Exchange (ETDEWEB)

Oi, S; Matsui, Y; Iizuka, M; Yamamoto, T

1977-01-01

Mesophilic methane fermentation was examined using soybean seed coat, a waste from soybean processing for oil manufacture, with or without treatment with hemicellulolytic enzymes of Aspergillus niger, and the following results were obtained: (1) The methane fermentation bacteria acclimated to soybean seed coat medium were shown to consume monosaccharides and evolve methane in the following decreasing order: glucose, fructose, mannose > xylose, galactose, glucosamine, galacturonic acid > arabinose. The bacteria were also shown to form methane from a gas mixture of hydrogen and carbon dioxide. (2) In fermentation of soybean seed coat treated with the fungal enzyme, about 70% of the total sugar content as consumed in four weeks, and the gas evolution was about twice that without the fungal enzyme. The gas evolved was composed of 60% methane and 36% carbon dioxide. In general, vigorous evolution of hydrogen and carbon dioxide occurred at a very early stage of fermentation, and was followed by formation of methane. The maximum gas evolution of the enzyme-treated mash took place in 6 days while that of untreated mash occurred one week later. Chemical oxygen demand of the supernatant of the former mash was decreased by fermentation to 7.0% of the initial level.

Effect of gamma irrigation followed by moderate temperature abuse on the psychrotrophic and mesophilic microbial association of frozen chicken

International Nuclear Information System (INIS)

Osman, M.E.

2001-01-01

Commercially scalded, plucked and eviscerated broilers, aerobically packed into polyethylene bags were irradiated at - 18 deg C. A dose of 2.5 kilogay was effective in the elimination of salmonella spp. and staphylococcus aureus. Psychrotrophic and mesophilic aerobic colony counts of the non-irradiated chicken were of the order 10**4 and 10**5 gE-1, respectively. Radiation resulted in approximately two long cycles reduction in the count. The surviving microflora in frozen chicken after irradiation consisted mainly of lactobacillus spp. and micrococcus spp. which dominated the mesophilic flora. Moraxella spp. amounted to 70% of the total psychrotrophic flora. The microflora of frozen chicken after temperature abuse at 12 deg C were maily of the moraxella-acinetobacter group and to a lesser extent of Pseudomonas spp. The results demonstrated that the microflora after temperature abuse of irradiated chicken was similar to the microflora of non-irradiated chicken. This supports the view that irradiation of chicken does not entail a hazard, resulting from a shift in the micrflora in case frozen chicken are thawed and stored at increased temperatures

The formation of illite from nontronite by mesophilic and thermophilic bacterial reaction

Science.gov (United States)

Jaisi, Deb P.; Eberl, Dennis D.; Dong, Hailiang; Kim, Jinwook

2011-01-01

The formation of illite through the smectite-to-illite (S-I) reaction is considered to be one of the most important mineral reactions occurring during diagenesis. In biologically catalyzed systems, however, this transformation has been suggested to be rapid and to bypass the high temperature and long time requirements. To understand the factors that promote the S-I reaction, the present study focused on the effects of pH, temperature, solution chemistry, and aging on the S-I reaction in microbially mediated systems. Fe(III)-reduction experiments were performed in both growth and non-growth media with two types of bacteria: mesophilic (Shewanella putrefaciens CN32) and thermophilic (Thermus scotoductus SA-01). Reductive dissolution of NAu-2 was observed and the formation of illite in treatment with thermophilic SA-01 was indicated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). A basic pH (8.4) and high temperature (65°C) were the most favorable conditions for the formation of illite. A long incubation time was also found to enhance the formation of illite. K-nontronite (non-permanent fixation of K) was also detected and differentiated from the discrete illite in the XRD profiles. These results collectively suggested that the formation of illite associated with the biologically catalyzed smectite-to-illite reaction pathway may bypass the prolonged time and high temperature required for the S-I reaction in the absence of microbial activity.

Study of physiological properties of some probiotics in multiple cultures with mesophilic lactic acid bacteria by Flora Danica Ch. Hansen commercial starter

Directory of Open Access Journals (Sweden)

DANIELA PARASCHIV

2011-12-01

Full Text Available The aim of this study was to establish the growth ability and stability of probiotic strains Lactobacillus acidophilus (commercial code La-5®, Lactobacillus casei ssp. paracasei (commercial code L. casei 431® and Bifidobacterium bifidus (commercial code BB-12® in multiple cultures with mesophilic lactic bacteria, Lactococcus lactis ssp. cremoris, Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. diacetylactis and Leuconostoc mesenteroides spp. cremoris, as Flora Danica Chr. Hansen commercial starters. Under the controlled fermentative conditions described below, a good starter combination, for the high rate of cells multiplication and for the good viability during storage, was identified in the mixture of L. casei 431®, BB-12® and Flora Danica, in ratio of 1:1:1 (9 log CFU/mL for each starter culture.

Enhanced fertilization effect of a compost obtained from mixed herbs waste inoculated with novel strains of mesophilic bacteria

Directory of Open Access Journals (Sweden)

Dimitrijević Snežana M.

2017-01-01

Full Text Available Mixed medicinal plant waste was composted with addition of novel bacterial strains belonging to the genera Streptomyces, Paenybacillus, Bacillus and Hymenobacter. The composting was followed by assessment of chemical and biological parameters including C/N ratio, loss of organic matter, phosphorous and potassium content as well as CO2 generation and dehydrogenase activity during 164 days. The selected mesophilic bacterial starters had a potential to significantly reduce the period of mixed herb waste decomposition, from about 6 months to about 2.5 months. Based on the seed germination index of four plants (Fagopirum esculentum, Thymus vulgaris, Cynara scolimus and Lavandula officinalis the germination and radial root growth of the investigated plants was improved by the inoculated compost. The germination index of all tested species on the mature inoculated composts was in average 60% higher compared to the control compost. The research indicates that the mesophilic starter addition into the herbs waste can contribute to the speed of waste decomposition and lead to the improvement of biofertilization effect of the obtained compost. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31035

Empowering a mesophilic inoculum for thermophilic nitrification: Growth mode and temperature pattern as critical proliferation factors for archaeal ammonia oxidizers.

Science.gov (United States)

Courtens, Emilie N P; Vandekerckhove, Tom; Prat, Delphine; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar H; Meerbergen, Ken; Lievens, Bart; Boon, Nico; Vlaeminck, Siegfried E

2016-04-01

Cost-efficient biological treatment of warm nitrogenous wastewaters requires the development of thermophilic nitrogen removal processes. Only one thermophilic nitrifying bioreactor was described so far, achieving 200 mg N L(-1) d(-1) after more than 300 days of enrichment from compost samples. From the practical point of view in which existing plants would be upgraded, however, a more time-efficient development strategy based on mesophilic nitrifying sludge is preferred. This study evaluated the adaptive capacities of mesophilic nitrifying sludge for two linear temperature increase patterns (non-oscillating vs. oscillating), two different slopes (0.25 vs. 0.08 °C d(-1)) and two different reactor types (floc vs. biofilm growth). The oscillating temperature pattern (0.25 °C d(-1)) and the moving bed biofilm reactor (0.08 °C d(-1)) could not reach nitrification at temperatures higher than 46 °C. However, nitrification rates up to 800 mg N L(-1) d(-1) and 150 mg N g(-1) volatile suspended solids d(-1) were achieved at a temperature as high as 49 °C by imposing the slowest linear temperature increase to floccular sludge. Microbial community analysis revealed that this successful transition was related with a shift in ammonium oxidizing archaea dominating ammonia oxidizing bacteria, while for nitrite oxidation Nitrospira spp. was constantly more abundant than Nitrobacter spp.. This observation was accompanied with an increase in observed sludge yield and a shift in maximal optimum temperature, determined with ex-situ temperature sensitivity measurements, predicting an upcoming reactor failure at higher temperature. Overall, this study achieved nitrification at 49 °C within 150 days by gradual adaptation of mesophilic sludge, and showed that ex-situ temperature sensitivity screening can be used to monitor and steer the transition process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of gamma irradiation followed by moderate temperature a buse on the psychrotrophic and mesophilic microbial association of frozen chicken

International Nuclear Information System (INIS)

Osman, M. E.

2001-01-01

commercially scalded, plucked and eviscerated broilers, aerobically packed into polyethylene bags were irradiated at -18 C. A dose of 2.5 kilo gay was effective in the elimination of salmonella spp and staphylococcus aureus. Psychrotrophic and mesophilic aerobic colony counts of the non-irradiated chicken were of the order 10 4 and 10 5 g -1 , respectively. Radiation resulted in approximately tow long cycles reduction in the count. The surviving microflora in frozen chicken after irradiation consisted mainly of lactobacillus spp. and micrococcus spp. which dominated the mesophilic flora. moraxella spp.amounted to 70% of the total Psychrotrophic flora. The microflora of frozen chicken after temperature abuse at 12 C were mainly of the moraxella-acinetobacter group and to a lesser extent of pseudomonas spp. The results demonstrated that the microflora after temperature abuse irradiated chicken was similar to the microflora of non-abuse irradiated chicken. This supports the view that irradiation of chicken dose not entail a hazard, resulting from a shift in the microflora in case frozen chicken are thawed and stored at increased temperatures.(Author)

Rapid establishment of thermophilic anaerobic microbial community during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester.

Science.gov (United States)

Tian, Zhe; Zhang, Yu; Li, Yuyou; Chi, Yongzhi; Yang, Min

2015-02-01

The purpose of this study was to explore how fast the thermophilic anaerobic microbial community could be established during the one-step startup of thermophilic anaerobic digestion from a mesophilic digester. Stable thermophilic anaerobic digestion was achieved within 20 days from a mesophilic digester treating sewage sludge by adopting the one-step startup strategy. The succession of archaeal and bacterial populations over a period of 60 days after the temperature increment was followed by using 454-pyrosequencing and quantitative PCR. After the increase of temperature, thermophilic methanogenic community was established within 11 days, which was characterized by the fast colonization of Methanosarcina thermophila and two hydrogenotrophic methanogens (Methanothermobacter spp. and Methanoculleus spp.). At the same time, the bacterial community was dominated by Fervidobacterium, whose relative abundance rapidly increased from 0 to 28.52 % in 18 days, followed by other potential thermophilic genera, such as Clostridium, Coprothermobacter, Anaerobaculum and EM3. The above result demonstrated that the one-step startup strategy could allow the rapid establishment of the thermophilic anaerobic microbial community. Copyright © 2014 Elsevier Ltd. All rights reserved.

Previously unclassified bacteria dominate during thermophilic and mesophilic anaerobic pre-treatment of primary sludge.

Science.gov (United States)

Pervin, Hasina M; Batstone, Damien J; Bond, Philip L

2013-06-01

Thermophilic biological pre-treatment enables enhanced anaerobic digestion for treatment of wastewater sludges but, at present, there is limited understanding of the hydrolytic-acidogenic microbial composition and its contribution to this process. In this study, the process was assessed by comparing the microbiology of thermophilic (50-65 °C) and mesophilic (35 °C) pre-treatment reactors treating primary sludge. A full-cycle approach for the 16S rRNA genes was applied in order to monitor the diversity of bacteria and their abundance in a thermophilic pre-treatment reactor treating primary sludge. For the thermophilic pre-treatment (TP), over 90% of the sequences were previously undetected and these had less than 97% sequence similarity to cultured organisms. During the first 83 days, members of the Betaproteobacteria dominated the community sequences and a newly designed probe was used to monitor a previously unknown bacterium affiliated with the genus Brachymonas. Between days 85 and 183, three phylotypes that affiliated with the genera Comamonas, Clostridium and Lysobacter were persistently dominant in the TP community, as revealed by terminal-restriction fragment length polymorphism (T-RFLP). Hydrolytic and fermentative functions have been speculated for these bacteria. Mesophilic pre-treatment (MP) and TP communities were different but they were both relatively dynamic. Statistical correlation analysis and the function of closely allied reference organisms indicated that previously unclassified bacteria dominated the TP community and may have been functionally involved in the enhanced hydrolytic performance of thermophilic anaerobic pre-treatment. This study is the first to reveal the diversity and dynamics of bacteria during anaerobic digestion of primary sludge. Copyright © 2013 Elsevier GmbH. All rights reserved.

Mesophilic anaerobic digestion of a mixture of cheese whey and dairy manure

Energy Technology Data Exchange (ETDEWEB)

Lo, K.V.; Liao, P.H.; Chiu, C.

1988-01-01

Mesophilic anaerobic digestion of a mixture of cheese whey and dairy manure was investigated using an anaerobic rotating biological contact reactor operated over a range of hydraulic retention time at various organic loading rates. Dairy manure provided nutrients and acted as a buffer to the cheese whey. Rates of production of methane from the mixture were between those of cheese whey and screened dairy manure and in agreement with calculated theoretical methane production rates. Methane production rate showed a linear relationship with the organic loading rate. The highest methane production rate was 3.74 liter methane litre/sup -1/ day/sup -1/. Reduction in the chemical oxygen demand ranged from 46.3% to 67.5%. Anaerobic digestion of such mixtures could be used as an initial waste treatment for cheese whey.

Hydrolytic activities of extracellular enzymes in thermophilic and mesophilic anaerobic sequencing-batch reactors treating organic fractions of municipal solid wastes.

Science.gov (United States)

Kim, Hyun-Woo; Nam, Joo-Youn; Kang, Seok-Tae; Kim, Dong-Hoon; Jung, Kyung-Won; Shin, Hang-Sik

2012-04-01

Extracellular enzymes offer active catalysis for hydrolysis of organic solid wastes in anaerobic digestion. To evidence the quantitative significance of hydrolytic enzyme activities for major waste components, track studies of thermophilic and mesophilic anaerobic sequencing-batch reactors (TASBR and MASBR) were conducted using a co-substrate of real organic wastes. During 1day batch cycle, TASBR showed higher amylase activity for carbohydrate (46%), protease activity for proteins (270%), and lipase activity for lipids (19%) than MASBR. In particular, the track study of protease identified that thermophilic anaerobes degraded protein polymers much more rapidly. Results revealed that differences in enzyme activities eventually affected acidogenic and methanogenic performances. It was demonstrated that the superior nature of enzymatic capability at thermophilic condition led to successive high-rate acidogenesis and 32% higher CH(4) recovery. Consequently, these results evidence that the coupling thermophilic digestion with sequencing-batch operation is a viable option to promote enzymatic hydrolysis of organic particulates. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comparative study on the selective chalcopyrite bioleaching of a molybdenite concentrate with mesophilic and thermophilic bacteria.

Science.gov (United States)

Romano, P; Blázquez, M L; Alguacil, F J; Muñoz, J A; Ballester, A; González, F

2001-03-01

This study evaluates different bioleaching treatments of a molybdenite concentrate using mesophilic and thermophilic bacterial cultures. Further studies on the chemical leaching and the electrochemical behavior of the MoS(2) concentrate were carried out. Bioleaching tests showed a progressive removal of chalcopyrite from the molybdenite concentrate with an increase in temperature. Chemical leaching tests support the idea of an indirect attack of the concentrate. Electrochemical tests indicate that chalcopyrite dissolution is favored when molybdenite is present. Therefore, this type of bioleaching treatment could be applied to purify molybdenite flotation concentrates by selectively dissolving chalcopyrite.

Survival, injury and inactivation of Escherichia coli 0157:H7, salmonella and aerobic mesophilic bacteria in apple juice and cider amended with nisin-edta

Science.gov (United States)

For health reasons, people are consuming fresh juices or minimally processed fruit and vegetable juices, thereby, exposing themselves to the risk of foodborne illness if such juices are contaminated with bacteria pathogens. Behavior of aerobic mesophilic bacteria, Escherichia coli O157:H7 and Salmon...

Application of Anaerobic Digestion Model No. 1 for simulating anaerobic mesophilic sludge digestion

International Nuclear Information System (INIS)

Mendes, Carlos; Esquerre, Karla; Matos Queiroz, Luciano

2015-01-01

Highlights: • The behavior of a anaerobic reactor was evaluated through modeling. • Parametric sensitivity analysis was used to select most sensitive of the ADM1. • The results indicate that the ADM1 was able to predict the experimental results. • Organic load rate above of 35 kg/m 3 day affects the performance of the process. - Abstract: Improving anaerobic digestion of sewage sludge by monitoring common indicators such as volatile fatty acids (VFAs), gas composition and pH is a suitable solution for better sludge management. Modeling is an important tool to assess and to predict process performance. The present study focuses on the application of the Anaerobic Digestion Model No. 1 (ADM1) to simulate the dynamic behavior of a reactor fed with sewage sludge under mesophilic conditions. Parametric sensitivity analysis is used to select the most sensitive ADM1 parameters for estimation using a numerical procedure while other parameters are applied without any modification to the original values presented in the ADM1 report. The results indicate that the ADM1 model after parameter estimation was able to predict the experimental results of effluent acetate, propionate, composites and biogas flows and pH with reasonable accuracy. The simulation of the effect of organic shock loading clearly showed that an organic shock loading rate above of 35 kg/m 3 day affects the performance of the reactor. The results demonstrate that simulations can be helpful to support decisions on predicting the anaerobic digestion process of sewage sludge

Application of Anaerobic Digestion Model No. 1 for simulating anaerobic mesophilic sludge digestion

Energy Technology Data Exchange (ETDEWEB)

Mendes, Carlos, E-mail: carllosmendez@gmail.com; Esquerre, Karla, E-mail: karlaesquerre@ufba.br; Matos Queiroz, Luciano, E-mail: lmqueiroz@ufba.br

2015-01-15

Highlights: • The behavior of a anaerobic reactor was evaluated through modeling. • Parametric sensitivity analysis was used to select most sensitive of the ADM1. • The results indicate that the ADM1 was able to predict the experimental results. • Organic load rate above of 35 kg/m{sup 3} day affects the performance of the process. - Abstract: Improving anaerobic digestion of sewage sludge by monitoring common indicators such as volatile fatty acids (VFAs), gas composition and pH is a suitable solution for better sludge management. Modeling is an important tool to assess and to predict process performance. The present study focuses on the application of the Anaerobic Digestion Model No. 1 (ADM1) to simulate the dynamic behavior of a reactor fed with sewage sludge under mesophilic conditions. Parametric sensitivity analysis is used to select the most sensitive ADM1 parameters for estimation using a numerical procedure while other parameters are applied without any modification to the original values presented in the ADM1 report. The results indicate that the ADM1 model after parameter estimation was able to predict the experimental results of effluent acetate, propionate, composites and biogas flows and pH with reasonable accuracy. The simulation of the effect of organic shock loading clearly showed that an organic shock loading rate above of 35 kg/m{sup 3} day affects the performance of the reactor. The results demonstrate that simulations can be helpful to support decisions on predicting the anaerobic digestion process of sewage sludge.

Crude oil degradation by bacterial consortia under four different redox and temperature conditions.

Science.gov (United States)

Xiong, Shunzi; Li, Xia; Chen, Jianfa; Zhao, Liping; Zhang, Hui; Zhang, Xiaojun

2015-02-01

There is emerging interest in the anaerobic degradation of crude oil. However, there is limited knowledge about the geochemical effects and microbiological activities for it. A mixture of anaerobic sludge and the production water from an oil well was used as an inoculum to construct four consortia, which were incubated under sulfate-reducing or methanogenic conditions at either mesophilic or thermophilic temperatures. Significant degradation of saturated and aromatic hydrocarbons and the changing quantities of some marker compounds, such as pristane, phytane, hopane and norhopane, and their relative quantities, suggested the activity of microorganisms in the consortia. Notably, the redox conditions and temperature strongly affected the diversity and structure of the enriched microbial communities and the oil degradation. Although some specific biomarker showed larger change under methanogenic condition, the degradation efficiencies for total aromatic and saturated hydrocarbon were higher under sulfate-reducing condition. After the 540-day incubation, bacteria of unknown classifications were dominant in the thermophilic methanogenic consortia, whereas Clostridium dominated the mesophilic methanogenic consortia. With the exception of the dominant phylotypes that were shared with the methanogenic consortia, the sulfate-reducing consortia were predominantly composed of Thermotogae, Deltaproteobacteria, Spirochaeta, and Synergistetes phyla. In conclusion, results in this study demonstrated that the different groups of degraders were responsible for degradation in the four constructed crude oil degrading consortia and consequently led to the existence of different amount of marker compounds under these distinct conditions. There might be distinct metabolic mechanism for degrading crude oil under sulfate-reducing and methanogenic conditions.

Antibiotic Multiresistance Analysis of Mesophilic and Psychrotrophic Pseudomonas spp. Isolated from Goat and Lamb Slaughterhouse Surfaces throughout the Meat Production Process

OpenAIRE

Lavilla Lerma, Leyre; Benomar, Nabil; Casado Muñoz, María del Carmen; Gálvez, Antonio; Abriouel, Hikmate

2014-01-01

The aim of this study was to investigate the phenotypic and genotypic antibiotic resistance profiles of pseudomonads isolated from surfaces of a goat and lamb slaughterhouse, which were representative of areas that are possible sources of meat contamination. Mesophilic (85 isolates) and psychrotrophic (37 isolates) pseudomonads identified at the species level generally were resistant to sulfamethoxazole, erythromycin, amoxicillin, ampicillin, chloramphenicol, trimethoprim, rifampin, and cefta...

Bioleaching of multiple heavy metals from contaminated sediment by mesophile consortium.

Science.gov (United States)

Gan, Min; Zhou, Shuang; Li, Mingming; Zhu, Jianyu; Liu, Xinxing; Chai, Liyuan

2015-04-01

A defined mesophile consortium including Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirilum ferriphilum was applied in bioleaching sediments contaminated with multiple heavy metals. Flask experiments showed that sulfur favored the acidification in the early stage while pyrite led to a great acidification potential in the later stage. An equal sulfur/pyrite ratio got the best acidification effect. Substrate utilization started with sulfur in the early stage, and then the pH decline and the community shift give rise to the utilization of pyrite. Solubilization efficiency of Zn, Cu, Mn, and Cd reached 96.1, 93.3, 92.13, and 87.65%, respectively. Bioleaching efficiency of other elements (As, Hg, Pb) was not more than 30%. Heavy metal solubilization was highly negatively correlated with pH variation. Logistic models were well fitted with the solubilization efficiency, which can be used to predict the bioleaching process. The dominant species in the early stage of bioleaching were A. ferrooxidans and A. thiooxidans, and the abundance of L. ferriphilum increased together with pyrite utilization and pH decline.

Importance of storage time in mesophilic anaerobic digestion of food waste.

Science.gov (United States)

Lü, Fan; Xu, Xian; Shao, Liming; He, Pinjing

2016-07-01

Storage was used as a pretreatment to enhance the methanization performance of mesophilic anaerobic digestion of food waste. Food wastes were separately stored for 0, 1, 2, 3, 4, 5, 7, and 12days, and then fed into a methanogenic reactor for a biochemical methane potential (BMP) test lasting up to 60days. Relative to the methane production of food waste stored for 0-1day (285-308mL/g-added volatile solids (VSadded)), that after 2-4days and after 5-12days of storage increased to 418-530 and 618-696mL/g-VSadded, respectively. The efficiency of hydrolysis and acidification of pre-stored food waste in the methanization reactors increased with storage time. The characteristics of stored waste suggest that methane production was not correlated with the total hydrolysis efficiency of organics in pre-stored food waste but was positively correlated with the storage time and acidification level of the waste. From the results, we recommend 5-7days of storage of food waste in anaerobic digestion treatment plants. Copyright © 2016. Published by Elsevier B.V.

Surface exposed amino acid differences between mesophilic and thermophilic phosphoribosyl diphosphate synthase

DEFF Research Database (Denmark)

Hove-Jensen, Bjarne; McGuire, James N

2004-01-01

The amino acid sequence of 5-phospho-alpha-D-ribosyl 1-diphosphate synthase from the thermophile Bacillus caldolyticus is 81% identical to the amino acid sequence of 5-phospho-alpha-D-ribosyl 1-diphosphate synthase from the mesophile Bacillus subtilis. Nevertheless the enzyme from the two organisms...... possesses very different thermal properties. The B. caldolyticus enzyme has optimal activity at 60-65 degrees C and a half-life of 26 min at 65 degrees C, compared to values of 46 degrees C and 60 s at 65 degrees C, respectively, for the B. subtilis enzyme. Chemical cross-linking shows that both enzymes...... are hexamers. Vmax is determined as 440 micromol.min(-1).mg protein(-1) and Km values for ATP and ribose 5-phosphate are determined as 310 and 530 microM, respectively, for the B. caldolyticus enzyme. The enzyme requires 50 mM Pi as well as free Mg2+ for maximal activity. Manganese ion substitutes for Mg2...

Molecular dynamics of mesophilic-like mutants of a cold-adapted enzyme: insights into distal effects induced by the mutations.

Directory of Open Access Journals (Sweden)

Elena Papaleo

Full Text Available Networks and clusters of intramolecular interactions, as well as their "communication" across the three-dimensional architecture have a prominent role in determining protein stability and function. Special attention has been dedicated to their role in thermal adaptation. In the present contribution, seven previously experimentally characterized mutants of a cold-adapted α-amylase, featuring mesophilic-like behavior, have been investigated by multiple molecular dynamics simulations, essential dynamics and analyses of correlated motions and electrostatic interactions. Our data elucidate the molecular mechanisms underlying the ability of single and multiple mutations to globally modulate dynamic properties of the cold-adapted α-amylase, including both local and complex unpredictable distal effects. Our investigation also shows, in agreement with the experimental data, that the conversion of the cold-adapted enzyme in a warm-adapted variant cannot be completely achieved by the introduction of few mutations, also providing the rationale behind these effects. Moreover, pivotal residues, which are likely to mediate the effects induced by the mutations, have been identified from our analyses, as well as a group of suitable candidates for protein engineering. In fact, a subset of residues here identified (as an isoleucine, or networks of mesophilic-like salt bridges in the proximity of the catalytic site should be considered, in experimental studies, to get a more efficient modification of the features of the cold-adapted enzyme.

Stability of endoglucanases from mesophilic fungus and thermophilic bacterium in acidified polyols.

Science.gov (United States)

Chong, Barrie Fong; Harrison, Mark D; O'Hara, Ian M

2014-01-01

Recent developments in chemical pretreatments of lignocellulosic biomass using polyols as co-solvents (e.g., glycerol and ethylene glycol) at temperatures less than 100°C may allow the effective use of thermostable and non-thermostable cellulases in situ during the saccharification process. The potential of biomass saccharifying enzymes, endoglucanases (EG) from a thermophilic bacterium (Thermotoga maritima) and a mesophilic fungus (Trichoderma longibrachiatum), to retain their activity in aqueous buffer, acidified glycerol, and acidified ethylene glycol used as co-solvents at pretreatment temperatures at or below 100°C were examined. The results show that despite its origin, T. longibrachiatum EG (Tl-EG) retained 75% of its activity after exposure to 100°C for 5 min in aqueous buffer while T. maritima EG (Tm-EG) retained only 5% activity. However, at 90°C both enzymes retained over 87% of their activity. In acidified (0.1% (w/w) H2SO4) glycerol, Tl-EG retained similar activity (80%) to that obtained in glycerol alone, while Tm-EG retained only 35%. With acidified ethylene glycol under these conditions, both Tl-EG and Tm-EG retained 36% of their activity. The results therefore show that Tl-EG is more stable in both acidified glycerol and ethylene glycol than Tm-EG. A preliminary kinetic study showed that pure glycerol improved the thermal stability of Tl-EG but destabilized Tm-EG, relative to the buffer solution. The half-lives of both Tl-EG and Tm-EG are 4.5 min in acidified glycerol, indicating that the effectiveness of these enzymes under typical pretreatment times of greater than 15 min will be considerably diminished. Attempts have been made to explain the differences in the results obtained between the two enzymes. Copyright © 2014 Elsevier Inc. All rights reserved.

Identification and characterization of a mesophilic phytase highly resilient to high-temperatures from a fungus-garden associated metagenome.

Science.gov (United States)

Tan, Hao; Wu, Xiang; Xie, Liyuan; Huang, Zhongqian; Peng, Weihong; Gan, Bingcheng

2016-03-01

Phytases are enzymes degrading phytic acid and thereby releasing inorganic phosphate. While the phytases reported to date are majorly from culturable microorganisms, the fast-growing quantity of publicly available metagenomic data generated in the last decade has enabled bioinformatic mining of phytases in numerous data mines derived from a variety of ecosystems throughout the world. In this study, we are interested in the histidine acid phosphatase (HAP) family phytases present in insect-cultivated fungus gardens. Using bioinformatic approaches, 11 putative HAP phytase genes were initially screened from 18 publicly available metagenomes of fungus gardens and were further overexpressed in Escherichia coli. One phytase from a south pine beetle fungus garden showed the highest activity and was then chosen for further study. Biochemical characterization showed that the phytase is mesophilic but possesses strong ability to withstand high temperatures. To our knowledge, it has the longest half-life time at 100 °C (27 min) and at 80 °C (2.1 h) as compared to all the thermostable phytases publicly reported to date. After 100 °C incubation for 15 min, more than 93 % of the activity was retained. The activity was 3102 μmol P/min/mg at 37 °C and 4135 μmol P/min/mg at 52.5 °C, which is higher than all the known thermostable phytases. For the high activity level demonstrated at mesophilic temperatures as well as the high resilience to high temperatures, the phytase might be promising for potential application as an additive enzyme in animal feed.

Study of physiological properties of some probiotics in multiple cultures with mesophilic lactic acid bacteria by Flora Danica Ch. Hansen commercial starter

OpenAIRE

DANIELA PARASCHIV; AIDA VASILE; MADALINA CONSTANTIN; ALEXANDRU CIOBANU; GABRIELA BAHRIM

2011-01-01

The aim of this study was to establish the growth ability and stability of probiotic strains Lactobacillus acidophilus (commercial code La-5®), Lactobacillus casei ssp. paracasei (commercial code L. casei 431®) and Bifidobacterium bifidus (commercial code BB-12®) in multiple cultures with mesophilic lactic bacteria, Lactococcus lactis ssp. cremoris, Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. diacetylactis and Leuconostoc mesenteroides spp. cremoris, as Flora Danica Chr. Hansen co...

A mesophilic Clostridium species that produces butanol from monosaccharides and hydrogen from polysaccharides.

Science.gov (United States)

Bramono, Sandhi Eko; Lam, Yuen Sean; Ong, Say Leong; He, Jianzhong

2011-10-01

A unique mesophilic Clostridium species strain BOH3 is obtained in this study, which is capable of fermenting monosaccharides to produce butanol and hydrolyzing polysaccharides to produce hydrogen (H(2)) and volatile fatty acids (VFAs). From 30 g/L of glucose and xylose each, batch culture BOH3 was able to produce 4.67 and 4.63 g/L of butanol. Enhancement treatments by increasing the inoculated cells improved butanol production to 7.05 and 7.41 g/L, respectively. Hydrogen production (2.47 and 1.93 mmol) was observed when cellulose and xylan (10 g/L each) were used, suggesting that strain BOH3 possesses xylanolytic and cellulolytic capabilities. These unique features reveal the strain's novelty as most wild-type solventogenic strains have not been reported to have such properties. Therefore, culture BOH3 is promising in generating butanol and hydrogen from renewable feedstock. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Mesophilic anaerobic treatment of sludge from saline fish farm effluents with biogas production

Energy Technology Data Exchange (ETDEWEB)

Gebauer, R. [Finnmark University College, Alta (Norway). Dept. of Aquaculture and Natural Sciences

2004-06-01

The mesophilic anaerobic treatment of sludge from saline fish farm effluents (total solids (TS): 8.2-10.2 wt%, chemical oxygen demand (COD): 60-74 g/l, sodium (Na): 10-10.5 g/l) was carried out in continuously stirred tank reactors (CSTRs) at 35 {sup o}C. COD stabilization between 36% and 55% and methane yields between 0.114 and 0.184 l/g COD added were achieved. However, the process was strongly inhibited, presumably by sodium, and unstable, with propionic acid being the main compound of the volatile fatty acids (VFA). When diluting the sludge 1:1 with tap water (Na: 5.3 g/l), the inhibition could be overcome and a stable process with low VFA concentrations was achieved. The results of the study are used to make recommendations for the configuration of full-scale treatment plants for the collected sludge from one salmon farming licence and to estimate the energy production from these plants. (Author)

Laboratory scale studies on the mesophilic anaerobic digestion of cheese whey in different digester configurations

Energy Technology Data Exchange (ETDEWEB)

Lo, K.V.; Liao, P.H.

1988-02-01

A two-phase system consisting of two reactors in series was used to study the mesophilic anaerobic digestion of cheese whey. A completely-mixed reactor and an anaerobic rotating biological contact reactor were used in series. The results indicated that ethanol and volatile fatty acids were the major products in the first reactor. Acidogenic pretreatment prior to the methanogenic phase resulted in an increase in methane production in the second reactor over that in one-stage digestion. High treatment efficiency in terms of reduction of chemical oxygen demand was also obtained for the two-phase digestion than that of the one-stage digestion. When comparing the system's performance in terms of methane production rate, the two-phase digestion had no advantage over the one-stage digestion.

The Effect of Different Additives and Medium on the Bioleaching of Molybdenite for Cu and Mo Extraction Using Mix Mesophilic Microorganism

Directory of Open Access Journals (Sweden)

Hadi Abdollahia

2013-06-01

Full Text Available Bioleaching processes for extraction of Cu and Mo from molybdenite cons. are more environmentally friendly and consume less energy than conventional technologies, yet less economically efficient. One necessary step towards arriving at a cost-effective bioleaching process is using appropriate methodology to optimize pertinent factors in such processes. To this end, the present study employed Response Surface Methodology to optimize important factors in a molybdenite bioleaching process by mix mesophilic microorganism using shake flasks. The effect of change in the levels of molybdenite concentration, pyrite and silver ion concentration as additives - in the range 3-9%, 1-5%, and 0-1.2gr/l, respectively - on the rate of Cu and Mo bioleaching was studied using a Central Composite Design. The results showed a statistically significant effect of silver ion and molybdenite concentration, and to a lesser pyrite concentration, on the rate of bioleaching of Cu and Mo. Further, different mediums and additives were evaluated for copper and molybdenum extraction from molybdenite concentrate in bioleaching process. Small amounts of silver (100mgr/l AgSO4 dramatically accelerated the copper dissolution process. Addition of FeS2 and sulfur with ferrous sulfate accelerated the acidification and raised the oxidation-reduction potential of solution (medium with an inoculation of 15% (v/v of active and adapted indigenous mesophilic bacteria, thus resulting in an overall increase in Mo dissolution efficiency.

Active sulfur cycling by diverse mesophilic and thermophilic microorganisms in terrestrial mud volcanoes of Azerbaijan.

Science.gov (United States)

Green-Saxena, A; Feyzullayev, A; Hubert, C R J; Kallmeyer, J; Krueger, M; Sauer, P; Schulz, H-M; Orphan, V J

2012-12-01

Terrestrial mud volcanoes (TMVs) represent geochemically diverse habitats with varying sulfur sources and yet sulfur cycling in these environments remains largely unexplored. Here we characterized the sulfur-metabolizing microorganisms and activity in four TMVs in Azerbaijan. A combination of geochemical analyses, biological rate measurements and molecular diversity surveys (targeting metabolic genes aprA and dsrA and SSU ribosomal RNA) supported the presence of active sulfur-oxidizing and sulfate-reducing guilds in all four TMVs across a range of physiochemical conditions, with diversity of these guilds being unique to each TMV. The TMVs varied in potential sulfate reduction rates (SRR) by up to four orders of magnitude with highest SRR observed in sediments where in situ sulfate concentrations were highest. Maximum temperatures at which SRR were measured was 60°C in two TMVs. Corresponding with these trends in SRR, members of the potentially thermophilic, spore-forming, Desulfotomaculum were detected in these TMVs by targeted 16S rRNA analysis. Additional sulfate-reducing bacterial lineages included members of the Desulfobacteraceae and Desulfobulbaceae detected by aprA and dsrA analyses and likely contributing to the mesophilic SRR measured. Phylotypes affiliated with sulfide-oxidizing Gamma- and Betaproteobacteria were abundant in aprA libraries from low sulfate TMVs, while the highest sulfate TMV harboured 16S rRNA phylotypes associated with sulfur-oxidizing Epsilonproteobacteria. Altogether, the biogeochemical and microbiological data indicate these unique terrestrial habitats support diverse active sulfur-cycling microorganisms reflecting the in situ geochemical environment. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions

DEFF Research Database (Denmark)

Johansen, Anders; Bangsø Nielsen, Henrik; Hansen, Christian M.

2013-01-01

did not affect egg survival during the first 48h and it took up to 10days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites......, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C...

Impacto dos mediadores redox na remoção de cor de corantes azo e antraquinônico por lodo granular anaeróbio sob condições mesofílicas e termofílicas Impact of redox mediators on colour removal of azo and anthraquinone dyes by anaerobic granular sludge under mesophilic and thermophilic conditions

Directory of Open Access Journals (Sweden)

André Bezerra dos Santos

2007-03-01

Full Text Available Investigou-se o efeito de diferentes mediadores redox (MR na remoção de cor de corantes azo e antraquinônico pelo uso de lodo granular anaeróbio sob condições mesofílicas (30ºC e termofílicas (55ºC. Comprovou-se em experimento em batelada que a adição de concentrações catalíticas de MR pode ter um efeito marcante nas taxas de descoloração do corante azo Reactive Red 2 (RR2, mas o mesmo comportamento não pode ser obtido com o corante antraquinônico Reactive Blue 5 (RB5. Entretanto, com ambos os corantes, o simples aumento da temperatura de incubação para condições termofílicas fez acelerar consideravelmente os processos de descoloração, comparados com condições mesofílicas. Por exemplo, a constante de primeira ordem "k" da redução dos corantes RR2 e RB5, foi aumentada em 6,2 e 11 vezes, respectivamente, à 55ºC quando comparado com 30ºC. Por fim, comprovou-se em experimentos de fluxo contínuo, a boa performance do tratamento termofílico na descoloração redutiva de corantes azo.The effect of different redox mediators (RM on colour removal of azo and anthraquinone dyes was investigated with anaerobic granular sludge under mesophilic (30ºC and thermophilic (55ºC conditions. Batch experiments revealed that an addition of catalytic concentrations of RM provided a remarkable effect on the decolourisation rates of the azo dye Reactive Red 2 (RR2, but the same effect could not be obtained with the anthraquinone dye Reactive Blue 5 (RB5. Nevertheless, for both dyes, the temperature increase to thermophilic conditions was an effective strategy to considerably accelerate the decolourisation process compared to mesophilic conditions. For instance, the first-order rate constant "k" of RR2 and RB5 reduction, was increased in 6.2 and 11-fold, respectively, at 55ºC in comparison with 30ºC. Such an effect of the temperature on the reductive decolourisation of azo dye was also verified in continuous flow experiments.

Anaerobic digestion of onion residuals using a mesophilic Anaerobic Phased Solids Digester

International Nuclear Information System (INIS)

Romano, Rowena T.; Zhang, Ruihong

2011-01-01

The anaerobic digestion of onion residual from an onion processing plant was studied under batch-fed and continuously-fed mesophilic (35 ± 2 o C) conditions in an Anaerobic Phased Solids (APS) Digester. The batch digestion tests were performed at an initial loading of 2.8 gVS L -1 and retention time of 14 days. The biogas and methane yields, and volatile solids reduction from the onion residual were determined to be 0.69 ± 0.06 L gVS -1 , 0.38 ± 0.05 L CH 4 gVS -1 , and 64 ± 17%, respectively. Continuous digestion tests were carried out at organic loading rates (OLRs) of 0.5-2.0 gVS L -1 d -1 . Hydrated lime (Ca(OH) 2 ) was added to the APS-Digester along with the onion residual at 16 mg Ca(OH) 2 gVS -1 to control the pH of the biogasification reactor above 7.0. At steady state the average biogas yields were 0.51, 0.56, and 0.62 L gVS -1 for the OLRs of 0.5, 1.0, and 2.0 gVS L -1 d -1 respectively. The methane yields at steady state were 0.29, 0.32, and 0.31 L CH 4 gVS -1 for the OLRs of 0.5, 1.0, and 2.0 gVS L -1 d -1 respectively. The study shows that the digestion of onion residual required proper alkalinity and pH control, which was possible through the use of caustic chemicals. However, such chemicals will begin to have an inhibitory effect on the microbial population at high loading rates, and therefore alternative operational parameters are needed. -- Highlights: → An APS-Digester was used to study biogas production from onion solid residues. → Biogas and methane yields from onion solids were determined. → Study showed substantial findings for treating onion solid residues.

Surface (glyco-)proteins: primary structure and crystallization under microgravity conditions

Science.gov (United States)

Claus, H.; Akca, E.; Schultz, N.; Karbach, G.; Schlott, B.; Debaerdemaeker, T.; De Clercq, J.-P.; König, H.

2001-08-01

The Archaea comprise microorganisms that live under environmental extremes, like high temperature, low pH value or high salt concentration. Their cells are often covered by a single layer of (glyco)protein subunits (S-layer) in hexagonal arrangement. In order to get further hints about the molecular mechanisms of protein stabilization we compared the primary and secondary structures of archaeal S-layer (glyco)proteins. We found an increase of charged amino acids in the S-layer proteins of the extreme thermophilic species compared to their mesophilic counterparts. Our data and those of other authors suggest that ionic interactions, e.g., salt bridges seem to be played a major role in protein stabilization at high temperatures. Despite the differences in the growth optima and the predominance of some amino acids the primary structures of S-layers revealed also a significant degree of identity between phylogenetically related archaea. These obervations indicate that protein sequences of S-layers have been conserved during the evolution from extremely thermophilic to mesophilic life. To support these findings the three-dimensional structure of the S-layer proteins has to be elucidated. Recently, we described the first successful crystallization of an extreme thermophilic surface(glyco)protein under microgravity conditions.

Biogas from mesophilic anaerobic digestion of cow dung using gelatin as additive

Science.gov (United States)

Salam, Bodius; Rahman, Md Mizanur; Sikder, Md Asif R.; Islam, Majedul

2017-06-01

A research work was conducted to investigate the enhanced production ability of biogas from mesophilic anaerobic digestions of cow dung (CD) using gelatin as additive. Five laboratory scale digesters were constructed to digest cow dung, where one set up was used for digestion of cow dung without additive and the other set up were used for digestion with additive. Gelatin additive was added in the slurry of amount 0.29, 0,57, 0.85 and 1.14% (wt.). The digesters were made of glass conical flask of 1-liter capacity each. Cow dung was used 335 gm and water was used 365 gm in each experiment. In the slurry, total solid content was maintained 8% (wt.) for all the observations. The digesters were fed on batch basis. The digesters were operated at ambient temperatures of 26 - 35°C. The total gas yield was obtained about 14.4 L/kg CD for digestion without additive and about 65% more biogas for digestion with 0.29% gelatin additive. The retention time for digestion without additive was 38 days and with additive retention time varied between 24 and 52 days.

Microbiological analysis of coliforms and mesophilic aerobic spore formers in gamma irradiated cocoa beans (Theobroma cacao L.); Analise microbiologica de coliformes e aerobicos mesofilos em amendoas de cacau (Theobroma cacao L.) irradiadas com radiacao gama

Energy Technology Data Exchange (ETDEWEB)

Barata, Anderson Demetrio; Mansur Netto, Elias [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Faculdade de Farmacia

1995-12-31

The presence of coliforms in processed foods is an useful indicator of post-sanitization and post processing contamination, and members of the mesophilic aerobic spore formers have great importance in food spoilage. Spore - forming aerobic bacilli have been observed in fermenting cocoa in Jamaica and West Africa. The results of this work has shown a considerable reduction of the mesophilic aerobic spore formers in irradiated Brazilian Comun Cocoa beans as long as the irradiation dose was increased from 1.05 to 3.99 kGy. The presence of coliforms irradiated has not been found even in the coroa beans with the dose of 1.05 kGy. (author). 4 refs., 1 tab.

Anaerobic mesophilic co-digestion of ensiled sorghum, cheese whey and liquid cow manure in a two-stage CSTR system: Effect of hydraulic retention time.

Science.gov (United States)

Dareioti, Margarita Andreas; Kornaros, Michael

2015-01-01

The aim of this study was to investigate the effect of hydraulic retention time (HRT) on hydrogen and methane production using a two-stage anaerobic process. Two continuously stirred tank reactors (CSTRs) were used under mesophilic conditions (37°C) in order to enhance acidogenesis and methanogenesis. A mixture of pretreated ensiled sorghum, cheese whey and liquid cow manure (55:40:5, v/v/v) was used. The acidogenic reactor was operated at six different HRTs of 5, 3, 2, 1, 0.75 and 0.5d, under controlled pH5.5, whereas the methanogenic reactor was operated at three HRTs of 24, 16 and 12d. The maximum H2 productivity (2.14L/LRd) and maximum H2 yield (0.70mol H2/mol carbohydrates consumed) were observed at 0.5d HRT. On the other hand, the maximum CH4 production rate of 0.90L/LRd was achieved at HRT of 16d, whereas at lower HRT the process appeared to be inhibited and/or overloaded. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pan-Cellulosomics of Mesophilic Clostridia: Variations on a Theme

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Bareket Dassa

2017-11-01

Full Text Available The bacterial cellulosome is an extracellular, multi-enzyme machinery, which efficiently depolymerizes plant biomass by degrading plant cell wall polysaccharides. Several cellulolytic bacteria have evolved various elaborate modular architectures of active cellulosomes. We present here a genome-wide analysis of a dozen mesophilic clostridia species, including both well-studied and yet-undescribed cellulosome-producing bacteria. We first report here, the presence of cellulosomal elements, thus expanding our knowledge regarding the prevalence of the cellulosomal paradigm in nature. We explored the genomic organization of key cellulosome components by comparing the cellulosomal gene clusters in each bacterial species, and the conserved sequence features of the specific cellulosomal modules (cohesins and dockerins, on the background of their phylogenetic relationship. Additionally, we performed comparative analyses of the species-specific repertoire of carbohydrate-degrading enzymes for each of the clostridial species, and classified each cellulosomal enzyme into a specific CAZy family, thus indicating their putative enzymatic activity (e.g., cellulases, hemicellulases, and pectinases. Our work provides, for this large group of bacteria, a broad overview of the blueprints of their multi-component cellulosomal complexes. The high similarity of their scaffoldin clusters and dockerin-based recognition residues suggests a common ancestor, and/or extensive horizontal gene transfer, and potential cross-species recognition. In addition, the sporadic spatial organization of the numerous dockerin-containing genes in several of the genomes, suggests the importance of the cellulosome paradigm in the given bacterial species. The information gained in this work may be utilized directly or developed further by genetically engineering and optimizing designer cellulosome systems for enhanced biotechnological biomass deconstruction and biofuel production.

Effect of feedstock composition and organic loading rate during the mesophilic co-digestion of olive mill wastewater and swine manure

DEFF Research Database (Denmark)

Kougias, Panagiotis; Kotsopoulos, T.A.; Martzopoulos, G.G.

2014-01-01

In the present study, the optimisation of the mesophilic anaerobic co-digestion process of olive mill wastewaters (OMW) together with swine manure (SM) was investigated. Batch and continuous mode experiments were performed in order to define the most efficient mixing ratio and to determine...... yield of the reactors fed with 40% OMW reached 373mL CH4/gVS (78% of the theoretical yield). The findings of the present study proved that the co-digestion of OMW together with SM is a sustainable solution, capable to efficiently treat simultaneously these residual residues. © 2014 Elsevier Ltd....

Isolation of cultivable thermophilic lactic acid bacteria from cheeses made with mesophilic starter and molecular comparison with dairy-related Lactobacillus helveticus strains

DEFF Research Database (Denmark)

Jensen, Marie Elisabeth Penderup; Ardö, Ylva Margareta; Vogensen, Finn Kvist

2009-01-01

-related Lact. helveticus strains indicated that one isolate was a Lact. helveticus. Partial sequencing of 16S rRNA confirmed this, and the remaining four strains were identified as Lactobacillus delbrueckii, Lactobacillus fermentum and Enterococcus faecium. The rep-PCR profile of the isolated Lact. helveticus......Aims: To isolate cultivable thermophilic lactic acid bacteria from cheeses made with mesophilic starter and compare them with dairy-related Lactobacillus helveticus strains using molecular typing methods. Methods and Results: The number of thermophilic bacteria in seven commercial cheeses...

Genome-Guided Analysis and Whole Transcriptome Profiling of the Mesophilic Syntrophic Acetate Oxidising Bacterium Syntrophaceticus schinkii.

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Shahid Manzoor

Full Text Available Syntrophaceticus schinkii is a mesophilic, anaerobic bacterium capable of oxidising acetate to CO2 and H2 in intimate association with a methanogenic partner, a syntrophic relationship which operates close to the energetic limits of microbial life. Syntrophaceticus schinkii has been identified as a key organism in engineered methane-producing processes relying on syntrophic acetate oxidation as the main methane-producing pathway. However, due to strict cultivation requirements and difficulties in reconstituting the thermodynamically unfavourable acetate oxidation, the physiology of this functional group is poorly understood. Genome-guided and whole transcriptome analyses performed in the present study provide new insights into habitat adaptation, syntrophic acetate oxidation and energy conservation. The working draft genome of Syntrophaceticus schinkii indicates limited metabolic capacities, with lack of organic nutrient uptake systems, chemotactic machineries, carbon catabolite repression and incomplete biosynthesis pathways. Ech hydrogenase, [FeFe] hydrogenases, [NiFe] hydrogenases, F1F0-ATP synthase and membrane-bound and cytoplasmic formate dehydrogenases were found clearly expressed, whereas Rnf and a predicted oxidoreductase/heterodisulphide reductase complex, both found encoded in the genome, were not expressed under syntrophic growth condition. A transporter sharing similarities to the high-affinity acetate transporters of aceticlastic methanogens was also found expressed, suggesting that Syntrophaceticus schinkii can potentially compete with methanogens for acetate. Acetate oxidation seems to proceed via the Wood-Ljungdahl pathway as all genes involved in this pathway were highly expressed. This study shows that Syntrophaceticus schinkii is a highly specialised, habitat-adapted organism relying on syntrophic acetate oxidation rather than metabolic versatility. By expanding its complement of respiratory complexes, it might overcome

Propensity for biofilm formation by aerobic mesophilic and thermophilic spore forming bacteria isolated from Chinese milk powders.

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Sadiq, Faizan A; Flint, Steve; Yuan, Lei; Li, Yun; Liu, TongJie; He, GuoQing

2017-12-04

Biofilms on the surface of dairy manufacturing plants are potential reservoirs of microbial contamination. These microbial aggregates may harbour pathogenic and spoilage organisms which contaminate dairy products. The biofilm forming capacity of many spore forming isolates of dairy origin has not been given much attention. The present study explored the biofilm forming potential of 148 isolates, comprising mesophilic and thermophilic bacteria, with particular emphasis on Bacillus licheniformis on polystyrene and stainless steel (SS) surfaces. We concluded that only four species are of significance for biofilm development on the surface of SS in the presence of skimmed milk, namely, B. licheniformis, Geobacillus stearothermophilus, Geobacillus thermoleovorans group and Anoxybacillus flavithermus. The maximum number of cells recovered from the biofilms developed on SS coupons in the presence of skimmed milk for these four species was as follows: 4.8, 5.2, 4.5 and 5.3logCFU/cm 2 , respectively. Number of cells recovered from biofilms on 1cm 2 SS coupons increased in the presence of tryptic soy broth (TSB) for all mesophiles including B. licheniformis, while decreased for G. stearothermophilus, G. thermoleovorans group and A. flavithermus. The crystal violet staining assay on polystyrene proved to be inadequate to predict cell counts on SS for the bacteria tested in our trial in the presence of either TSB or skimmed milk. The results support the idea that biofilm formation is an important part of bacterial survival strategy as only the most prevalent isolates from milk powders formed good biofilms on SS in the presence of skimmed milk. Biofilm formation also proved to be a strain-dependent characteristic and interestingly significant variation in biofilm formation was observed within the same RAPD groups of B. licheniformis which supports the previously reported genetic and phenotypic heterogeneity within the same RAPD based groups. The work reported in this manuscript

Development and Diversity of Lactococcus lactis and Leuconostoc Bacteriophages in Dairies Using Undefined Mesophilic DL-Starter Cultures

DEFF Research Database (Denmark)

Muhammed, Musemma Kedir

complete loss of fermentation. Dairy phages have for long time been studied using traditional culture-dependent methods but not using metagenomic approaches. Part of this project was devoted to develop a method for dairy metavirome extraction and analysis. Several whey mixtures derived by defined......Bacteriophages (phages) attacking strains of Lactococcus (Lc.) lactis and Leuconostoc species, used as starter cultures in mesophilic dairy productions, produce huge problems through waste of ingredients, increased processing time, reduced product quality, consistency and safety, and occasionally...... in dairies using undefined starters and of mostly Lc. lactis c2 phages in dairies using defined cultures. Certain evidence indicating possible co-induction of temperate P335 phages and smaller Lc. lactis satellite phages was obtained. Also addressed was the issue of accurate and simultaneous quantification...

Domain-swapping of mesophilic xylanase with hyper-thermophilic glucanase

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Liu Liangwei

2012-06-01

Full Text Available Abstract Background Domain fusion is limited at enzyme one terminus. The issue was explored by swapping a mesophilic Aspergillus niger GH11 xylanase (Xyn with a hyper-thermophilic Thermotoga maritima glucanase (Glu to construct two chimeras, Xyn-Glu and Glu-Xyn, with an intention to create thermostable xylanase containing glucanase activity. Results When expressed in E. coli BL21(DE3, the two chimeras exhibited bi-functional activities of xylanase and glucanase. The Xyn-Glu Xyn moiety had optimal reaction temperature (Topt at 50 °C and thermal in-activation half-life (t1/2 at 50 °C for 47.6 min, compared to 47 °C and 17.6 min for the Xyn. The Glu-Xyn Xyn moiety had equivalent Topt to and shorter t1/2 (5.2 min than the Xyn. Both chimera Glu moieties were more thermostable than the Glu, and the three enzyme Topt values were higher than 96 °C. The Glu-Xyn Glu moiety optimal pH was 5.8, compared to 3.8 for the Xyn-Glu Glu moiety and the Glu. Both chimera two moieties cooperated with each other in degrading substrates. Conclusions Domain-swapping created different effects on each moiety properties. Fusing the Glu domain at C-terminus increased the xylanase thermostability, but fusing the Glu domain at N-terminus decreased the xylanase thermostability. Fusing the Xyn domain at either terminus increased the glucanase thermostability, and fusing the Xyn domain at C-terminus shifted the glucanase pH property 2 units higher towards alkaline environments. Fusing a domain at C-terminus contributes more to enzyme catalytic activity; whereas, fusing a bigger domain at N-terminus disturbs enzyme substrate binding affinity.

Influence of temperature shifts on survival, growth, and toxin production by psychrotrophic and mesophilic strains of Bacillus cereus in potatoes and chicken gravy.

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Mahakarnchanakul, W; Beuchat, L R

1999-03-15

A study was done to determine the influence of temperature on growth and toxin production characteristics of psychrotrophic and mesophilic strains of Bacillus cereus when inoculated into mashed potatoes and chicken gravy containing various concentrations of sodium chloride and held at temperatures different from those at which cells had been cultured. Logarithmic growth phase cells (10 h, 30 degrees C) of psychrotrophic (F3802A/84) and mesophilic (B4ac-1) strains of Bacillus cereus were inoculated into rehydrated commercially processed instant mashed potatoes and chicken gravy supplemented with 0, 2, or 4% sodium chloride. Growth, survival, and diarrheal toxin production in potatoes and gravy held at 30, 37, and 10 degrees C (strain F3802A/84) or 30, 40, and 10 degrees C (strain B4ac-1) were monitored. Both strains grew in both foods containing no added sodium chloride or 2% sodium chloride when held at 30, 37, or 40 degrees C for 2 days. Strain B4ac-1 grew better than strain F3802A/84 in foods containing 4% sodium chloride. Maximum amounts of enterotoxin (1024 ng/g) were produced by strain B4ac-1 in chicken gravy held at 30 and 40 degrees C. Strain F3802A/84 grew to populations of 7 log10 CFU/g in foods containing no added sodium chloride or 2% sodium chloride at 10 degrees C. Strain F3802A/84 produced the highest amount of enterotoxin (1024 ng/g) at 30 degrees C in chicken gravy containing 0.7 or 2% sodium chloride; however, little or low amounts of toxin (4-16 ng/g) were produced in chicken gravy at 10 degrees C. Compared to strain B4ac-1, cells of strain F3802A/84 subjected to a downward shift in incubation temperature (10 degrees C) grew more rapidly in chicken gravy. Strain B4ac-1 produced the highest amount of toxin (1024 ng/g) at 30 degrees C in gravy containing 4% sodium chloride and at 40 degrees C in gravy containing 0.7% sodium chloride. Toxin was not detected in inoculated mashed potatoes. Results of this study indicate that shifts in incubation

Following changes in total number of mesophilic bacteria and torry meter readings in samples of fresh trout packaged in modified atmosphere and vacuum

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Milijašević Milan

2011-01-01

Full Text Available Today, food must be healthy, subjected to minimal processing, and attractively packaged, as the expectations of consumers are ever higher. Consumers are highly sensitive to the use of additives in the food industry. There is a constant demand for fresh food that does not contain any unnecessarily added chemicals. In order to prevent spoilage of food items, an efficient and intelligent concept for preserving freshness has been developed - packaging in a modified atmosphere. Changes in a certain composition of the atmosphere within the packaging have resulted in a longer shelf life and a satisfactory quality of the food articles. Modified atmosphere packaging (MAP is well-known and has been applied in practice in the food processing industry for more than one century. The objective of these investigations was to determine the growth of the total number of mesophilic bacteria in the meat of trout packaged in a vacuum and a modified atmosphere and torry meter reading results due to changes in the dielectric characteristics of the skin that take place during the period of storage of the fresh fish. California trout (Oncorhynchus mykiss with an average weight of 293 g was used for the experimental part of the investigations. Four groups of fish samples were set up for the research. The first three groups of samples were packaged in a modified atmosphere with a different ratio of gases: Group I - 60%CO2+40%N2; Group II - 40%CO2+60%N2; Group III - 90%CO2+10%N2. Group IV comprised samples packaged in a vacuum. Investigations were carried out on days 0, 7, 14, and 21 of storage. The total number of mesophilic bacteria in the examined samples was determined according to the method ISO 4833. Measurements of changes in the dielectric characteristics of the fish skin were performed using a torry meter apparatus (The Torry Fish Freshness Meter. The results have shown that packaging of fresh trout in a modified atmosphere (60% CO2 + 40% N2 and 40% CO2 + 60% N2

Lignocellulose-derived thin stillage composition and efficient biological treatment with a high-rate hybrid anaerobic bioreactor system

KAUST Repository

Oosterkamp, Margreet J.; Mé ndez-Garcí a, Celia; Kim, Chang-H.; Bauer, Stefan; Ibá ñ ez, Ana B.; Zimmerman, Sabrina; Hong, Pei-Ying; Cann, Isaac K.; Mackie, Roderick I.

2016-01-01

Results showed that thin stillage contains easily degradable compounds suitable for anaerobic digestion and that hybrid reactors can efficiently convert thin stillage to methane under mesophilic and thermophilic conditions. Furthermore, we found that optimal conditions for biological treatment of thin stillage were similar for both mesophilic and thermophilic reactors. Bar-coded pyrosequencing of the 16S rRNA gene identified different microbial communities in mesophilic and thermophilic reactors and these differences in the microbial communities could be linked to the composition of the thin stillage.

Isolation and characterization of mesophilic, oxalate-degrading Streptomyces from plant rhizosphere and forest soils

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Sahin, Nurettin

2004-10-01

The present work was aimed at the isolation of additional new pure cultures of oxalate-degrading Streptomyces and its preliminary characterization for further work in the field of oxalate metabolism and taxonomic studies. Mesophilic, oxalate-degrading Streptomyces were enriched and isolated from plant rhizosphere and forest soil samples. Strains were examined for cultural, morphological (spore chain morphology, spore mass colour, diffusible and melanin pigment production), physiological (antibiosis, growth in the presence of inhibitory compounds, assimilation of organic acids and enzyme substrates) and chemotaxonomic characters (cellular lipid components and diagnostic cell-wall diamino acid). The taxonomic data obtained were analysed by using the simple matching (SSM) and Jaccard (SJ) coefficients, clustering was achieved using the UPGMA algorithm. All strains were able to utilize sodium-, potassium-, calcium- and ammonium-oxalate salts. Based on the results of numerical taxonomy, isolates were grouped into five cluster groups with a ≥70% SSM similarity level. Streptomyces rochei was the most common of the cluster groups, with a Willcox probability of P>0.8. Streptomyces antibioticus, S. anulatus, S. fulvissimus, S. halstedii and S. violaceusniger are newly reported as oxalate-utilizing Streptomyces.

Drivers of microbial community composition in mesophilic and thermophilic temperature-phased anaerobic digestion pre-treatment reactors.

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Pervin, Hasina M; Dennis, Paul G; Lim, Hui J; Tyson, Gene W; Batstone, Damien J; Bond, Philip L

2013-12-01

Temperature-phased anaerobic digestion (TPAD) is an emerging technology that facilitates improved performance and pathogen destruction in anaerobic sewage sludge digestion by optimising conditions for 1) hydrolytic and acidogenic organisms in a first-stage/pre-treatment reactor and then 2) methogenic populations in a second stage reactor. Pre-treatment reactors are typically operated at 55-65 °C and as such select for thermophilic bacterial communities. However, details of key microbial populations in hydrolytic communities and links to functionality are very limited. In this study, experimental thermophilic pre-treatment (TP) and control mesophilic pre-treatment (MP) reactors were operated as first-stages of TPAD systems treating activated sludge for 340 days. The TP system was operated sequentially at 50, 60 and 65 °C, while the MP rector was held at 35 °C for the entire period. The composition of microbial communities associated with the MP and TP pre-treatment reactors was characterised weekly using terminal-restriction fragment length polymorphism (T-RFLP) supported by clone library sequencing of 16S rRNA gene amplicons. The outcomes of this approach were confirmed using 454 pyrosequencing of gene amplicons and fluorescence in-situ hybridisation (FISH). TP associated bacterial communities were dominated by populations affiliated to the Firmicutes, Thermotogae, Proteobacteria and Chloroflexi. In particular there was a progression from Thermotogae to Lutispora and Coprothermobacter and diversity decreased as temperature and hydrolysis performance increased. While change in the composition of TP associated bacterial communities was attributable to temperature, that of MP associated bacterial communities was related to the composition of the incoming feed. This study determined processes driving the dynamics of key microbial populations that are correlated with an enhanced hydrolytic functionality of the TPAD system. Copyright © 2013 Elsevier Ltd. All rights

[Street food: analysis of hygienic and sanitary conditions of food handlers].

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de Souza, Giovanna Carbonera; dos Santos, Celso Tadeu Barbosa; Andrade, Anderson Assunção; Alves, Luciene

2015-08-01

The consumption of street food is an economical and practical alternative for the population. However, concerns regarding the safety of these foods are increasing. Thus, this study aimed to analyze the hygienic and sanitary conditions of the street food trade in Uberaba in the State of Minas Gerais. For this purpose, 30 street vending sites were evaluated using a structured questionnaire and microbiological analysis of food handlers' hands and food contact recipients and surfaces. The findings showed low adequacy of street food regarding hand hygiene and food contact surfaces. With respect to surfaces, the results for mesophilic aerobic microorganisms revealed that only 23.3% had satisfactory sanitary conditions. The level of contamination of hands by fecal thermotolerant coliforms and/or Coagulase positive Staphylococci was unsatisfactory in approximately 47% of food handlers. The conclusion drawn is that the hygienic and sanitary conditions of food handlers in Uberaba are poor. It is therefore necessary to adopt effective and permanent training programs on food safety for food handlers urgently.

Effect of maize silage addition on biomethane recovery from mesophilic co-digestion of chicken and cattle manure to suppress ammonia inhibition

International Nuclear Information System (INIS)

Yangin-Gomec, Cigdem; Ozturk, Izzet

2013-01-01

Highlights: • Daily biomethane and total energy productions improved 1.2 fold when maize silage is co-digested with the animal wastes. • Heat produced is sufficient for successful mesophilic co-digestion with an energy saving ∼36 × 10 3 kW h with maize silage. • Excess heat up to 16 × 10 3 kW h can be utilized elsewhere in the premises of the biogas plant. • Biogas plants including co-digestion of manure with a suitable co-substrate are becoming net producers of renewable energy. • pH values above 7.4 may cause severe inhibition of methanogenic cultures for an unadapted process to NH 3 . - Abstract: The aim of this study is to evaluate the biogas recovery potential if mesophilic (35 ± 2 °C) anaerobic co-digestion of two different types of manure sources (from chicken and cattle) is applied at a biogas plant. In order to evaluate the improvement in biogas production in the presence of the co-substrate, maize silage is digested together with the animal manure. Results indicated that daily biomethane and total energy (power + heat) productions improved about 1.2 fold when maize silage is co-digested with cattle and chicken wastes. The heat and power energy potentials from the produced biogas were determined using the conversion rates of a CHP unit. Significant energy recovery could be achieved for both cases; i.e. total methane productions were calculated as 5800 and 6580 m 3 /day corresponding to total energy productions of some 45.05 × 10 3 and 51.06 × 10 3 kW h without and with maize silage addition, respectively. A heat analysis was also performed where the resulting biomethane productions were the basis of the heat requirements. Results indicated that the major part of the heating requirements consisted of slurry heating to the operating temperature (in this study 35 °C). When the overall heat requirements are compared to the heat potential from a CHP unit, it is clear that the heat produced is sufficient for successful mesophilic co

"Hot cores" in proteins: Comparative analysis of the apolar contact area in structures from hyper/thermophilic and mesophilic organisms

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Bossa Francesco

2008-02-01

Full Text Available Abstract Background A wide variety of stabilizing factors have been invoked so far to elucidate the structural basis of protein thermostability. These include, amongst the others, a higher number of ion-pairs interactions and hydrogen bonds, together with a better packing of hydrophobic residues. It has been frequently observed that packing of hydrophobic side chains is improved in hyperthermophilic proteins, when compared to their mesophilic counterparts. In this work, protein crystal structures from hyper/thermophilic organisms and their mesophilic homologs have been compared, in order to quantify the difference of apolar contact area and to assess the role played by the hydrophobic contacts in the stabilization of the protein core, at high temperatures. Results The construction of two datasets was carried out so as to satisfy several restrictive criteria, such as minimum redundancy, resolution and R-value thresholds and lack of any structural defect in the collected structures. This approach allowed to quantify with relatively high precision the apolar contact area between interacting residues, reducing the uncertainty due to the position of atoms in the crystal structures, the redundancy of data and the size of the dataset. To identify the common core regions of these proteins, the study was focused on segments that conserve a similar main chain conformation in the structures analyzed, excluding the intervening regions whose structure differs markedly. The results indicated that hyperthermophilic proteins underwent a significant increase of the hydrophobic contact area contributed by those residues composing the alpha-helices of the structurally conserved regions. Conclusion This study indicates the decreased flexibility of alpha-helices in proteins core as a major factor contributing to the enhanced termostability of a number of hyperthermophilic proteins. This effect, in turn, may be due to an increased number of buried methyl groups in

Thermophilic Alkaline Fermentation Followed by Mesophilic Anaerobic Digestion for Efficient Hydrogen and Methane Production from Waste-Activated Sludge: Dynamics of Bacterial Pathogens as Revealed by the Combination of Metagenomic and Quantitative PCR Analyses.

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Wan, Jingjing; Jing, Yuhang; Rao, Yue; Zhang, Shicheng; Luo, Gang

2018-03-15

Thermophilic alkaline fermentation followed by mesophilic anaerobic digestion (TM) for hydrogen and methane production from waste-activated sludge (WAS) was investigated. The TM process was also compared to a process with mesophilic alkaline fermentation followed by a mesophilic anaerobic digestion (MM) and one-stage mesophilic anaerobic digestion (M) process. The results showed that both hydrogen yield (74.5 ml H 2 /g volatile solids [VS]) and methane yield (150.7 ml CH 4 /g VS) in the TM process were higher than those (6.7 ml H 2 /g VS and 127.8 ml CH 4 /g VS, respectively) in the MM process. The lowest methane yield (101.2 ml CH 4 /g VS) was obtained with the M process. Taxonomic results obtained from metagenomic analysis showed that different microbial community compositions were established in the hydrogen reactors of the TM and MM processes, which also significantly changed the microbial community compositions in the following methane reactors compared to that with the M process. The dynamics of bacterial pathogens were also evaluated. For the TM process, the reduced diversity and total abundance of bacterial pathogens in WAS were observed in the hydrogen reactor and were further reduced in the methane reactor, as revealed by metagenomic analysis. The results also showed not all bacterial pathogens were reduced in the reactors. For example, Collinsella aerofaciens was enriched in the hydrogen reactor, which was also confirmed by quantitative PCR (qPCR) analysis. The study further showed that qPCR was more sensitive for detecting bacterial pathogens than metagenomic analysis. Although there were some differences in the relative abundances of bacterial pathogens calculated by metagenomic and qPCR approaches, both approaches demonstrated that the TM process was more efficient for the removal of bacterial pathogens than the MM and M processes. IMPORTANCE This study developed an efficient process for bioenergy (H 2 and CH 4 ) production from WAS and elucidates the

Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions.

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Johansen, Anders; Nielsen, Henrik B; Hansen, Christian M; Andreasen, Christian; Carlsgart, Josefine; Hauggard-Nielsen, Henrik; Roepstorff, Allan

2013-04-01

Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this practice may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seeds of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37°C) and thermophilic (55°C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55°C) was very clear as complete mortality, irrespective of weed species, was reached after less than 2 days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzinckia micrantha still maintained low levels (~1%) of germination ability after 1 week. Chenopodium album was the only weed species which survived 1 week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55°C, no Ascaris eggs survived more than 3h of incubation. Incubation at 37°C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests. Copyright © 2012 Elsevier Ltd. All rights reserved.

A comparative molecular dynamics study of thermophilic and mesophilic β-fructosidase enzymes.

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Mazola, Yuliet; Guirola, Osmany; Palomares, Sucel; Chinea, Glay; Menéndez, Carmen; Hernández, Lázaro; Musacchio, Alexis

2015-09-01

Arabidopsis thaliana cell wall invertase 1 (AtcwINV1) and Thermotoga maritima β-fructosidase (BfrA) are among the best structurally studied members of the glycoside hydrolase family 32. Both enzymes hydrolyze sucrose as the main substrate but differ strongly in their thermal stability. Mesophilic AtcwINV1 and thermophilic BfrA have divergent sequence similarities in the N-terminal five bladed β-propeller catalytic domain (31 %) and the C-terminal β-sandwich domain (15 %) of unknown function. The two enzymes were subjected to 200 ns molecular dynamics simulations at 300 K (27 °C) and 353 K (80 °C). Regular secondary structure regions, but not loops, in AtcwINV1 and BfrA showed no significant fluctuation differences at both temperatures. BfrA was more rigid than AtcwINV1 at 300 K. The simulation at 353 K did not alter the structural stability of BfrA, but did increase the overall flexibility of AtcwINV1 exhibiting the most fluctuating regions in the β-propeller domain. The simulated heat treatment also increased the gyration radius and hydrophobic solvent accessible surface area of the plant enzyme, consistent with the initial steps of an unfolding process. The preservation of the conformational rigidity of BfrA at 353 K is linked to the shorter size of the protein loops. Shortening of BfrA loops appears to be a key mechanism for thermostability.

High-solid mesophilic methane fermentation of food waste with an emphasis on Iron, Cobalt, and Nickel requirements.

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Qiang, Hong; Lang, Dong-Li; Li, Yu-You

2012-01-01

The effect of trace metals on the mesophilic methane fermentation of high-solid food waste was investigated using both batch and continuous experiments. The continuous experiment was conducted by using a CSTR-type reactor with three run. During the first run, the HRT of the reactor was stepwise decreased from 100 days to 30 days. From operation day 50, the reactor efficiency deteriorated due to the lack of trace metals. The batch experiment showed that iron, cobalt, and nickel combinations had a significant effect on food waste. According to the results of the batch experiment, a combination of iron, cobalt, and nickel was added into the CSTR reactor by two different methods at run II, and III. Based on experimental results and theoretical calculations, the most suitable values of Fe/COD, Co/COD, and Ni/COD in the substrate were identified as 200, 6.0, and 5.7 mg/kg COD, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

In situ Removal of Hydrogen Sulfide During Biogas Fermentation at Microaerobic Condition.

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Wu, Mengmeng; Zhang, Yima; Ye, Yuanyuan; Lin, Chunmian

2016-11-01

In this paper, rice straw was used as a raw material to produce biogas by anaerobic batch fermentation at 35 °C (mesophilic) or 55 °C (thermophilic). The hydrogen sulfide in biogas can be converted to S 0 or sulfate and removed in-situ under micro-oxygen environment. Trace oxygen was conducted to the anaerobic fermentation tank in amount of 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, or 10.0 times stoichiometric equivalence, respectively, and the control experiment without oxygen addition was carried out. The results showed that the initial H 2 S concentrations of biogas are about 3235 ± 185 mg/m 3 (mesophilic) or 3394 ± 126 mg/m 3 (thermophilic), respectively. The desulfurization efficiency is 72.3 % (mesophilic) or 65.6 % (thermophilic), respectively, with oxygen addition by stoichiometric relation. When the oxygen feeded in amount of 2∼4 times, theoretical quantity demanded the removal efficiency of hydrogen sulfide could be over 92 %, and the oxygen residue in biogas could be maintained less than 0.5 %, which fit the requirement of biogas used as vehicle fuel or combined to the grid. Though further more oxygen addition could promote the removal efficiency of hydrogen sulfide (about 93.6 %), the oxygen residue in biogas would be higher than the application limit concentration (0.5 %). Whether mesophilic or thermophilic fermentation with the extra addition of oxygen, there were no obvious changes in the gas production and methane concentration. In conclusion, in-situ desulfurization can be achieved in the anaerobic methane fermentation system under micro-oxygen environment. In addition, air could be used as a substitute oxygen resource on the situation without strict demand for the methane content of biogas.

Hemicellulose conversion by anaerobic digestion

Energy Technology Data Exchange (ETDEWEB)

Ghosh, S; Honry, M P; Christopher, R W

1985-01-01

This research was undertaken to study the digestibility of the hemicellulose fractions of an aquatic biomass, a land-based biomass and a biomass-waste blend under various fermentation conditions. The conversion of hemicellulose was higher than those of cellulose and protein under the mesophilic condition. Hemicellulose was converted at a much lower efficency than cellulose during thermophilic digestion. In contrast, cellulose conversion was about the same under mesophilic and thermophilic conditions. Cellulose was utilized in preference to hemicellulose during mesophilic fermentation of nitrogen-supplemented Bermuda grass. It was speculated that Bermuda grass cellulose was converted at a higher efficiency than hemicellulose in the pressure of external nitrogen because the metabolism of the breakdown product (glucose) of cellulose required the least investment of enzymes and energy. 4 references.

Production of an acidic and thermostable lipase of the mesophilic fungus Penicillium simplicissimum by solid-state fermentation.

Science.gov (United States)

Gutarra, Melissa L E; Godoy, Mateus G; Maugeri, Francisco; Rodrigues, Maria Isabel; Freire, Denise M G; Castilho, Leda R

2009-11-01

The production of a lipase by a wild-type Brazilian strain of Penicillium simplicissimum in solid-state fermentation of babassu cake, an abundant residue of the oil industry, was studied. The enzyme production reached about 90 U/g in 72 h, with a specific activity of 4.5 U/mg of total proteins. The crude lipase showed high activities at 35-60 degrees C and pH 4.0-6.0, with a maximum activity at 50 degrees C and pH 4.0-5.0. Enzyme stability was enhanced at pH 5.0 and 6.0, with a maximum half-life of 5.02 h at 50 degrees C and pH 5.0. Thus, this lipase shows a thermophilic and thermostable behavior, what is not common among lipases from mesophilic filamentous fungi. The crude enzyme catalysed the hydrolysis of triglycerides and p-nitrophenyl esters (C4:0-C18:0), preferably acting on substrates with medium-chain fatty acids. This non-purified lipase in addition to interesting properties showed a reduced production cost making feasible its applicability in many fields.

Anaerobic carbon monoxide metabolism by Pleomorphomonas carboxyditropha sp. nov., a new mesophilic hydrogenogenic carboxydotroph.

Science.gov (United States)

Esquivel-Elizondo, Sofia; Maldonado, Juan; Krajmalnik-Brown, Rosa

2018-06-01

Carbon monoxide (CO)-metabolism and phenotypic and phylogenetic characterization of a novel anaerobic, mesophilic and hydrogenogenic carboxydotroph are reported. Strain SVCO-16 was isolated from anaerobic sludge and grows autotrophically and mixotrophically with CO. The genes cooS and cooF, coding for a CO dehydrogenase complex, and genes similar to hycE2, encoding a CO-induced hydrogenase, were present in its genome. The isolate produces H2 and CO2 from CO, and acetate and formate from organic substrates. Based on the 16S rRNA sequence, it is an Alphaproteobacterium most closely related to the genus Pleomorphomonas (98.9%-99.2% sequence identity). Comparison with other previously characterized Pleomorphomonas showed that P. diazotrophica and P. oryzae do not metabolize CO, and P. diazotrophica does not grow anaerobically with organic substrates. Average nucleotide identity values between strain SVCO-16 and P. diazotrophica, P. oryzae or P. koreensis were 86.66 ± 0.21%. These values are below the boundary to define species (95%-96%). Digital DNA-DNA hybridization estimates between strain SVCO-16 and reference strains were also below the 70% threshold for species delineation: 29.1%-34.5%. Based on the differences in CO metabolism, genome analyses and cellular fatty acid composition, the isolate should be classified into the genus Pleomorphomonas as a representative of a novel species, Pleomorphomonas carboxyditropha. The type strain of Pleomorphomonas carboxyditropha is SVCO-16T (strain deposit numbers, DSM 106132T and TSD-119T).

New Strategy for a Suitable Fast Stabilization of the Biomethanization Performance

Science.gov (United States)

Fernández-Güelfo, L. A.; Álvarez-Gallego, C. J.; Sales Márquez, D.; Romero García, L. I.

2012-01-01

The start-up strategies for thermophilic anaerobic reactors usually consist of an initial mesophilic stage (35°C), with an approximate duration of 185 days, and a subsequent thermophilic stage (55°C), which normally requires around 60 days to achieve the system stabilizatio. During the first 8–10 days of the mesophilic stage, the reactor is not fed so that the inoculum, which is generally a mesophilic anaerobic sludge, may be adapted to the organic solid waste. Between mesophilic and thermophilic conditions the reactor is still not fed in an effort to prevent possible imbalances in the proces. As a consequence, the start-up and stabilization of the biomethanization performance described in the literature require, at least, around 245 days. In this sense, a new strategy for the start-up and stabilization phases is presented in this study. This approach allows an important reduction in the overall time necessary for these stages in an anaerobic continuous stirred tank reactor (CSTR) operated at thermophilic-dry conditions for treating the organic fraction of the municipal solid waste (OFMSW): 60 days versus 245 days of conventional strategies. The new strategy uses modified SEBAC technology to adapt an inoculum to the OFMSW and the operational conditions prior to seeding the CSTR. PMID:23193374

New Strategy for a Suitable Fast Stabilization of the Biomethanization Performance

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L. A. Fernández-Güelfo

2012-01-01

Full Text Available The start-up strategies for thermophilic anaerobic reactors usually consist of an initial mesophilic stage (35°C, with an approximate duration of 185 days, and a subsequent thermophilic stage (55°C, which normally requires around 60 days to achieve the system stabilizatio. During the first 8–10 days of the mesophilic stage, the reactor is not fed so that the inoculum, which is generally a mesophilic anaerobic sludge, may be adapted to the organic solid waste. Between mesophilic and thermophilic conditions the reactor is still not fed in an effort to prevent possible imbalances in the proces. As a consequence, the start-up and stabilization of the biomethanization performance described in the literature require, at least, around 245 days. In this sense, a new strategy for the start-up and stabilization phases is presented in this study. This approach allows an important reduction in the overall time necessary for these stages in an anaerobic continuous stirred tank reactor (CSTR operated at thermophilic-dry conditions for treating the organic fraction of the municipal solid waste (OFMSW: 60 days versus 245 days of conventional strategies. The new strategy uses modified SEBAC technology to adapt an inoculum to the OFMSW and the operational conditions prior to seeding the CSTR.

Biogas production and methanogenic archaeal community in mesophilic and thermophilic anaerobic co-digestion processes.

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Yu, D; Kurola, J M; Lähde, K; Kymäläinen, M; Sinkkonen, A; Romantschuk, M

2014-10-01

Over 258 Mt of solid waste are generated annually in Europe, a large fraction of which is biowaste. Sewage sludge is another major waste fraction. In this study, biowaste and sewage sludge were co-digested in an anaerobic digestion reactor (30% and 70% of total wet weight, respectively). The purpose was to investigate the biogas production and methanogenic archaeal community composition in the anaerobic digestion reactor under meso- (35-37 °C) and thermophilic (55-57 °C) processes and an increasing organic loading rate (OLR, 1-10 kg VS m(-3) d(-1)), and also to find a feasible compromise between waste treatment capacity and biogas production without causing process instability. In summary, more biogas was produced with all OLRs by the thermophilic process. Both processes showed a limited diversity of the methanogenic archaeal community which was dominated by Methanobacteriales and Methanosarcinales (e.g. Methanosarcina) in both meso- and thermophilic processes. Methanothermobacter was detected as an additional dominant genus in the thermophilic process. In addition to operating temperatures, the OLRs, the acetate concentration, and the presence of key substrates like propionate also affected the methanogenic archaeal community composition. A bacterial cell count 6.25 times higher than archaeal cell count was observed throughout the thermophilic process, while the cell count ratio varied between 0.2 and 8.5 in the mesophilic process. This suggests that the thermophilic process is more stable, but also that the relative abundance between bacteria and archaea can vary without seriously affecting biogas production. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

Science.gov (United States)

Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

2016-01-15

With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simultaneous addition of zero-valent iron and activated carbon on enhanced mesophilic anaerobic digestion of waste-activated sludge.

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Wang, Tongyu; Qin, Yujie; Cao, Yan; Han, Bin; Ren, Junyi

2017-10-01

The performance of biogas generation and sludge degradation was studied under different zero-valent iron/activated carbon (ZVI/AC) ratios in detail in mesophilic anaerobic digestion of sludge. A good enhancement of methane production was obtained at the 10:1 ZVI/AC ratio, and the cumulative methane production was 132.1 mL/g VS, 37.6% higher than the blank. The methane content at the 10:1 ZVI/AC ratio reached 68.8%, which was higher than the blank (55.2%) and the sludge-added AC alone (59.6%). For sludge degradation, the removal efficiencies of total chemical oxygen demand (TCOD), proteins, and polysaccharides were all the highest at the 10:1 ZVI/AC ratio. The concentration of available phosphorus (AP) decreased after anaerobic digestion process. On the other hand, the concentrations of available nitrogen (AN) and available potassium (AK) increased after the anaerobic digestion process and showed a gradually decreasing trend with increasing ZVI/AC ratio. The concentrations of AN and AK were 2303.1-4200.3 and 274.7-388.3 mg/kg, showing a potential for land utilization.

Performance evaluation of a mesophilic (37 deg. C) upflow anaerobic sludge blanket reactor in treating distiller's grains wastewater

International Nuclear Information System (INIS)

Gao Mengchun; She Zonglian; Jin Chunji

2007-01-01

The performance of a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor treating distiller's grains wastewater was investigated for 420 days at 37 deg. C. After a successful start-up, 80-97.3% chemical oxygen demand (COD) removal efficiencies were achieved at hydraulic retention times (HRT) of 82-11 h with organic loading rates (OLR) of 5-48.3 kg COD m -3 d -1 . The biogas mainly consisted of methane and carbon dioxide, and the methane and carbon dioxide content in the biogas was 57-60 and 38-41%, respectively. The yield coefficient of methane production was 0.3182 l CH 4 g -1 COD removed until OLR at 33.3 kg COD m -3 d -1 , but afterwards began to decrease. The volatile fatty acid (VFA) in the effluent mainly consisted of acetate and propionate, accounting for more than 95% of total VFA as COD, and other VFA was detected at insignificant concentrations. The mesophilic granules developed in this study showed an excellent specific methanogenic activity (SMA) at 0.91 and 1.12 g methane COD g -1 VSS -1 d -1 using sucrose and acetate as individual substrates on day 200, respectively

Financial appraisal of wet mesophilic AD technology as a renewable energy and waste management technology.

Science.gov (United States)

Dolan, T; Cook, M B; Angus, A J

2011-06-01

Anaerobic digestion (AD) has the potential to support diversion of organic waste from landfill and increase renewable energy production. However, diffusion of this technology has been uneven, with countries such as Germany and Sweden taking the lead, but limited diffusion in other countries such as the UK. In this context, this study explores the financial viability of AD in the UK to offer reasons why it has not been more widely used. This paper presents a model that calculates the Internal Rate of Return (IRR) on a twenty year investment in a 30,000 tonnes per annum wet mesophilic AD plant in the UK for the treatment of source separated organic waste, which is judged to be a suitable technology for the UK climate. The model evaluates the financial significance of the different alternative energy outputs from this AD plant and the resulting economic subsidies paid for renewable energy. Results show that renewable electricity and renewable heat sales supported by renewable electricity and renewable heat tariffs generates the greatest IRR (31.26%). All other uses of biogas generate an IRR in excess of 15%, and are judged to be a financially viable investment. Sensitivity analysis highlights the financial significance of: economic incentive payments and a waste management gate fee; and demonstrates that the fate of the digestate by-product is a source of financial uncertainty for AD investors. Copyright © 2011 Elsevier B.V. All rights reserved.

High-temperature fermentation. How can processes for ethanol production at high temperatures become superior to the traditional process using mesophilic yeast?

Energy Technology Data Exchange (ETDEWEB)

Abdel-Banat, Babiker M.A.; Hoshida, Hisashi; Nonklang, Sanom; Akada, Rinji [Yamaguchi Univ. Graduate School of Medicine, Ube (Japan). Dept. of Applied Molecular Bioscience; Ano, Akihiko [Iwata Chemical Co. Ltd. (Japan)

2010-01-15

The process of ethanol fermentation has a long history in the production of alcoholic drinks, but much larger scale production of ethanol is now required to enable its use as a substituent of gasoline fuels at 3%, 10%, or 85% (referred to as E3, E10, and E85, respectively). Compared with fossil fuels, the production costs are a major issue for the production of fuel ethanol. There are a number of possible approaches to delivering cost-effective fuel ethanol production from different biomass sources, but we focus in our current report on high-temperature fermentation using a newly isolated thermotolerant strain of the yeast Kluyveromyces marxianus. We demonstrate that a 5 C increase only in the fermentation temperature can greatly affect the fuel ethanol production costs. We contend that this approach may also be applicable to the other microbial fermentations systems and propose that thermotolerant mesophilic microorganisms have considerable potential for the development of future fermentation technologies. (orig.)

Functional organization of a single nif cluster in the mesophilic archaeon Methanosarcina mazei strain Gö1

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Claudia Ehlers

2002-01-01

Full Text Available The mesophilic methanogenic archaeon Methanosarcina mazei strain Gö1 is able to utilize molecular nitrogen (N2 as its sole nitrogen source. We have identified and characterized a single nitrogen fixation (nif gene cluster in M. mazei Gö1 with an approximate length of 9 kbp. Sequence analysis revealed seven genes with sequence similarities to nifH, nifI1, nifI2, nifD, nifK, nifE and nifN, similar to other diazotrophic methanogens and certain bacteria such as Clostridium acetobutylicum, with the two glnB-like genes (nifI1 and nifI2 located between nifH and nifD. Phylogenetic analysis of deduced amino acid sequences for the nitrogenase structural genes of M. mazei Gö1 showed that they are most closely related to Methanosarcina barkeri nif2 genes, and also closely resemble those for the corresponding nif products of the gram-positive bacterium C. acetobutylicum. Northern blot analysis and reverse transcription PCR analysis demonstrated that the M. mazei nif genes constitute an operon transcribed only under nitrogen starvation as a single 8 kb transcript. Sequence analysis revealed a palindromic sequence at the transcriptional start site in front of the M. mazei nifH gene, which may have a function in transcriptional regulation of the nif operon.

Sanitary condition of electrical hand dryers in toilets of shopping centres in Kraków

Directory of Open Access Journals (Sweden)

Anna Lenart-Boroń

2015-06-01

Full Text Available Introduction. Shopping habits have changed over the past several years and consumers choose shopping centres, where they can spend time and visit restaurants. People usually wash hands before meals, but toilets in shopping centres are visited by hundreds of users every day which makes their cleanliness questionable. Therefore, the aim of this study was to assess the sanitary condition of electrical hand dryers in toilets of the selected shopping centres in Kraków. Material and methods. Air was sampled at the outlet of electrical hand dryers and surface swabs of hand dryers were taken in toilets of five shopping centres. Air sampling was conducted using the MAS-100 impactor. The number of mesophilic bacteria, fungi, actinomycetes, staphylococci and Escherichia coli was determined. The results of air analyses were compared with the limits provided by the Polish Standards on air quality. Results. The number of microorganisms varied between the studied centres. In terms of mesophilic bacteria and fungi the air was unpolluted. The concentration of actinomycetes however significantly exceeded the limits set by the Polish Standards. Numerous Escherichia coli were found both in the air and in swabs in one of the centres. However the number of E. coli and staphylococci did not exceed the minimum infective dose. Conclusions. The studies showed high concentrations of airborne actinomycetes and staphylococci. Also the presence of E. coli in the air and swabs allows the conclusion that legal regulations for concentrations of airborne microorganisms are necessary to make people aware of this problem. However, it was found that using electrical hand dryers does not have impact on human health.

Anaerobic bioconversion of organic waste into biogas by hot water treatment at near-critical conditions: application in bioregenerative life support.

Science.gov (United States)

Lissens, Geert; Verstraete, Willy; Albrecht, Tobias; Brunner, Gerd; Lasseur, Christophe

2003-01-01

The feasibility of nearly-complete conversion of lignocellulosic waste (70% food crops, 20% faecal matter and 10% green algae) into biogas was investigated in the context of a Life Support Project. The treatment comprised a series of processes, i.e. a mesophilic laboratory scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor and a hydrothermolysis system in near-critical water. By the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 l biogas g(-1) VSS (volatile suspended solids) added at a HRT (hydraulic retention time) of 20 d was obtained. Biogas yields further increased with 10-15% at HRT > 20 d, indicating the hydrolysis of lignocellulose to be the rate-limiting conversion step. The solids present in the CSTR-effluent were subsequently treated by hot water treatment (T approximately 310-350 degrees C, p approximately 240 bar), resulting in effective carbon liquefaction (50-60% without and 83% with carbon dioxide saturation) and complete hygienisation of the residue. Subsequent anaerobic digestion of the hydrolysate allowed further conversion of 48-60% on COD (chemical oxygen demand) basis. Thus, the total process yielded biogas corresponding with a COD conversion up to 90% of the original organic matter. It appears that mesophilic digestion in conjunction with hydrothermolysis at near-critical conditions offers interesting features for (nearly) complete, non-toxic and hygienic carbon and energy recovery from human waste in a bioregenerative life support context.

Food waste co-digestion with slaughterhouse waste and sewage sludge: Digestate conditioning and supernatant quality.

Science.gov (United States)

Borowski, Sebastian; Boniecki, Paweł; Kubacki, Przemysław; Czyżowska, Agata

2018-04-01

In this study, the anaerobic mesophilic co-digestion of food waste (FW) with municipal sewage sludge (MSS) and slaughterhouse waste (SHW) was undertaken in 3-dm 3 laboratory reactors as well as in 50-dm 3 reactors operated in semi-continuous conditions. The highest methane yield of around 0.63 m 3 CH 4 /kgVS fed was achieved for the mixture of FW and SHW treated in the laboratory digester operated at solids retention time (SRT) of 30 days, whereas the co-digestion of FW with MSS under similar operating conditions produced 0.46 m 3 of methane from 1 kgVS fed . No significant differences between methane yields from laboratory digesters and large-scale reactors were reported. The conditioning tests with the digestates from reactor experiments revealed the highest efficiency of inorganic coagulants among all investigated chemicals, which applied in a dose of 10 g/kg allowed to reduce capiliary suction time (CST) of the digestate below 20 s. The combined conditioning with coagulants and bentonite did not further reduce the CST value but improved the quality of the digestate supernatant. In particular, the concentrations of suspended solids, COD as well as metals in the supernatant were considerably lowered. Copyright © 2017. Published by Elsevier Ltd.

The impact of furfural concentrations and substrate-to-biomass ratios on biological hydrogen production from synthetic lignocellulosic hydrolysate using mesophilic anaerobic digester sludge.

Science.gov (United States)

Akobi, Chinaza; Hafez, Hisham; Nakhla, George

2016-12-01

This study evaluated the impact of furfural (a furan derivative) on hydrogen production rates and yields at initial substrate-to-microorganism ratios (S°/X°) of 4, 2, 1, and 0.5gCOD/gVSS and furfural concentrations of 4, 2, 1, and 0.5g/L. Fermentation studies were carried out in batches using synthetic lignocellulosic hydrolysate as substrate and mesophilic anaerobic digester sludge as seed. Contrary to other literature studies where furfural was inhibitory, this study showed that furfural concentrations of up to 1g/L enhanced hydrogen production with yields as high as 19% from the control (batch without furfural). Plots of hydrogen yields against gfurfural/gsugars and hydrogen yields versus gfurfural/gbiomass showed negative linear correlation indicating that these parameters influence biohydrogen production. Regression analysis indicated that gfurfural/gsugars initial exerted a greater effect on the degree of inhibition of hydrogen production than gfurfural/gVSS final . Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacteria and archaea communities in full-scale thermophilic and mesophilic anaerobic digesters treating food wastewater: Key process parameters and microbial indicators of process instability.

Science.gov (United States)

Lee, Joonyeob; Shin, Seung Gu; Han, Gyuseong; Koo, Taewoan; Hwang, Seokhwan

2017-12-01

In this study, four different mesophilic and thermophilic full-scale anaerobic digesters treating food wastewater (FWW) were monitored for 1-2years in order to investigate: 1) microbial communities underpinning anaerobic digestion of FWW, 2) significant factors shaping microbial community structures, and 3) potential microbial indicators of process instability. Twenty-seven bacterial genera were identified as abundant bacteria underpinning the anaerobic digestion of FWW. Methanosaeta harundinacea, M. concilii, Methanoculleus bourgensis, M. thermophilus, and Methanobacterium beijingense were revealed as dominant methanogens. Bacterial community structures were clearly differentiated by digesters; archaeal community structures of each digester were dominated by one or two methanogen species. Temperature, ammonia, propionate, Na + , and acetate in the digester were significant factors shaping microbial community structures. The total microbial populations, microbial diversity, and specific bacteria genera showed potential as indicators of process instability in the anaerobic digestion of FWW. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combined thermophilic aerobic process and conventional anaerobic digestion: effect on sludge biodegradation and methane production.

Science.gov (United States)

Dumas, C; Perez, S; Paul, E; Lefebvre, X

2010-04-01

The efficiency of hyper-thermophilic (65 degrees Celsius) aerobic process coupled with a mesophilic (35 degrees Celsius) digester was evaluated for the activated sludge degradation and was compared to a conventional mesophilic digester. For two Sludge Retention Time (SRT), 21 and 42 days, the Chemical Oxygen Demand (COD) solubilisation and biodegradation processes, the methanisation yield and the aerobic oxidation were investigated during 180 days. The best results were obtained at SRT of 44 days; the COD removal yield was 30% higher with the Mesophilic Anaerobic Digestion/Thermophilic Aerobic Reactor (MAD-TAR) co-treatment. An increase of the sludge intrinsic biodegradability is also observed (20-40%), showing that the unbiodegradable COD in mesophilic conditions becomes bioavailable. However, the methanisation yield was quite similar for both processes at a same SRT. Finally, such a process enables to divide by two the volume of digester with an equivalent efficiency. Copyright 2009 Elsevier Ltd. All rights reserved.

Monitoring transitory profiles of leachate humic substances in landfill aeration reactors in mesophilic and thermophilic conditions

Energy Technology Data Exchange (ETDEWEB)

Tong, Huanhuan [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 (Singapore); School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Yin, Ke; Ge, Liya; Giannis, Apostolos [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 (Singapore); Chuan, Valerie W.L. [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Wang, Jing-Yuan, E-mail: JYWANG@ntu.edu.sg [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One, 637141 (Singapore); School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

2015-04-28

Highlights: • Polymerization and condensation of humic substances (HS) were enhanced by aeration. • Carboxylic group was enriched in HS by aeration presenting improved hydrophilicity. • Mobility of humic acid, as a result was enhanced by aeration especially in young landfill. • Waste age plays an important role in leachate management during aeration. - Abstract: The presence of humic substances (HS) in landfill leachate is of great interest because of their structural stability and potential toxicity. This study examined the effects of temperature and waste age on the transformation of HS during in situ aeration of bioreactor landfills. By establishing aerobic conditions, dissolved organic carbon (DOC) rapidly accumulated in the bioreactor leachate. Fractional analysis showed that the elevated concentration of humic acids (HAs) was primarily responsible for the increment of leachate strength. Further structural characterization indicated that the molecular weight (MW) and aromacity of HS were enhanced by aeration in conjunction with thermophilic temperature. Interestingly, elevation of HAs concentration was not observed in the aeration reactor with a prolonged waste age, as the mobility of HAs was lowered by the high MW derived from extended waste age. Based on these results, aeration may be more favorable in aged landfills, since dissolution of HAs could be minimized by the evolution to larger MW compared to young landfills. Moreover, increased operation temperature during aeration likely offers benefits for the rapid maturation of HS.

Investigations on the inactivation of selected bacteria and viruses during mesophilic and thermophilic anaerobic alkaline cofermentation of biological waste materials, food residues and other animal residues; Seuchenhygienische Untersuchungen zur Inaktivierung ausgewaehlter Bakterien und Viren bei der mesophilen und thermophilen anaeroben alkalischen Faulung von Bio- und Kuechenabfaellen sowie anderen Rest- und Abfallstoffen tierischer Herkunft

Energy Technology Data Exchange (ETDEWEB)

Hoferer, M. [Hohenheim Univ., Stuttgart (Germany). Inst. fuer Umwelt- und Tierhygiene sowie Tiermedizin mit Tierklinik

2001-07-01

The purpose of this study is to investigate the inactivation kinetics of a number of different bacteria (Salmonella Senftenberg, Escherichia coli O157, Enterococcus faecium) and viruses (Bovine Enterovirus (ECBO), Equine Rhinovirus (ERV), Poliovirus, Bovine Parvovirus (BPV)) during the process of anaerobic cofermentation. Experiments were conducted in a semi-technical biogas plant at the University of Hohenheim. The fermenter was fed with a mixture of slurry from pigs or cattle (75%) and leftovers (25%) and was run under mesophilic (30 C + 35 C) as well as under thermophilic temperature conditions (50 C + 55 C). Volume and filter-sandwich germ-carriers were specifically developed and/or optimised for these analyses. Parallel to the experiments at the University of Hohenheim and under almost identical process conditions, various viruses (African Swine Fever Virus, Pseudorabies Virus, Classical Swine Fever Virus, Foot and Mouth Disease Virus, Swine Vesicular Disease Virus) were examined at the Federal Research Centre for Virus Diseases of Animals in Tuebingen. The results obtained at each research institution are directly compared. (orig.)

Lignocellulose-derived thin stillage composition and efficient biological treatment with a high-rate hybrid anaerobic bioreactor system

KAUST Repository

Oosterkamp, Margreet J.

2016-06-06

Background This study aims to chemically characterize thin stillage derived from lignocellulosic biomass distillation residues in terms of organic strength, nutrient, and mineral content. The feasibility of performing anaerobic digestion on these stillages at mesophilic (40 °C) and thermophilic (55 °C) temperatures to produce methane was demonstrated. The microbial communities involved were further characterized. Results Energy and sugar cane stillage have a high chemical oxygen demand (COD of 43 and 30 g/L, respectively) and low pH (pH 4.3). Furthermore, the acetate concentration in sugar cane stillage was high (45 mM) but was not detected in energy cane stillage. There was also a high amount of lactate in both types of stillage (35–37 mM). The amount of sugars was 200 times higher in energy cane stillage compared to sugar cane stillage. Although there was a high concentration of sulfate (18 and 23 mM in sugar and energy cane stillage, respectively), both thin stillages were efficiently digested anaerobically with high COD removal under mesophilic and thermophilic temperature conditions and with an organic loading rate of 15–21 g COD/L/d. The methane production rate was 0.2 L/g COD, with a methane percentage of 60 and 64, and 92 and 94 % soluble COD removed, respectively, by the mesophilic and thermophilic reactors. Although both treatment processes were equally efficient, there were different microbial communities involved possibly arising from the differences in the composition of energy cane and sugar cane stillage. There was more acetic acid in sugar cane stillage which may have promoted the occurrence of aceticlastic methanogens to perform a direct conversion of acetate to methane in reactors treating sugar cane stillage. Conclusions Results showed that thin stillage contains easily degradable compounds suitable for anaerobic digestion and that hybrid reactors can efficiently convert thin stillage to methane under mesophilic and thermophilic conditions

Lignocellulose-derived thin stillage composition and efficient biological treatment with a high-rate hybrid anaerobic bioreactor system.

Science.gov (United States)

Oosterkamp, Margreet J; Méndez-García, Celia; Kim, Chang-H; Bauer, Stefan; Ibáñez, Ana B; Zimmerman, Sabrina; Hong, Pei-Ying; Cann, Isaac K; Mackie, Roderick I

2016-01-01

This study aims to chemically characterize thin stillage derived from lignocellulosic biomass distillation residues in terms of organic strength, nutrient, and mineral content. The feasibility of performing anaerobic digestion on these stillages at mesophilic (40 °C) and thermophilic (55 °C) temperatures to produce methane was demonstrated. The microbial communities involved were further characterized. Energy and sugar cane stillage have a high chemical oxygen demand (COD of 43 and 30 g/L, respectively) and low pH (pH 4.3). Furthermore, the acetate concentration in sugar cane stillage was high (45 mM) but was not detected in energy cane stillage. There was also a high amount of lactate in both types of stillage (35-37 mM). The amount of sugars was 200 times higher in energy cane stillage compared to sugar cane stillage. Although there was a high concentration of sulfate (18 and 23 mM in sugar and energy cane stillage, respectively), both thin stillages were efficiently digested anaerobically with high COD removal under mesophilic and thermophilic temperature conditions and with an organic loading rate of 15-21 g COD/L/d. The methane production rate was 0.2 L/g COD, with a methane percentage of 60 and 64, and 92 and 94 % soluble COD removed, respectively, by the mesophilic and thermophilic reactors. Although both treatment processes were equally efficient, there were different microbial communities involved possibly arising from the differences in the composition of energy cane and sugar cane stillage. There was more acetic acid in sugar cane stillage which may have promoted the occurrence of aceticlastic methanogens to perform a direct conversion of acetate to methane in reactors treating sugar cane stillage. Results showed that thin stillage contains easily degradable compounds suitable for anaerobic digestion and that hybrid reactors can efficiently convert thin stillage to methane under mesophilic and thermophilic conditions. Furthermore, we found

Microbial community structure in a thermophilic aerobic digester used as a sludge pretreatment process for the mesophilic anaerobic digestion and the enhancement of methane production.

Science.gov (United States)

Jang, Hyun Min; Park, Sang Kyu; Ha, Jeong Hyub; Park, Jong Moon

2013-10-01

An effective two-stage sewage sludge digestion process, consisting of thermophilic aerobic digestion (TAD) followed by mesophilic anaerobic digestion (MAD), was developed for efficient sludge reduction and methane production. Using TAD as a biological pretreatment, the total volatile suspended solid reduction (VSSR) and methane production rate (MPR) in the MAD reactor were significantly improved. According to denaturing gradient gel electrophoresis (DGGE) analysis, the results indicated that the dominant bacteria species such as Ureibacillus thermophiles and Bacterium thermus in TAD were major routes for enhancing soluble organic matter. TAD pretreatment using a relatively short SRT of 1 day showed highly increased soluble organic products and positively affected an increment of bacteria populations which performed interrelated microbial metabolisms with methanogenic species in the MAD; consequently, a quantitative real-time PCR indicated greatly increased Methanosarcinales (acetate-utilizing methanogens) in the MAD, resulting in enhanced methane production. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Model of Solar Energy Utilisation in the Anaerobic Digestion of Cattle Manure

NARCIS (Netherlands)

Mashad, El H.; Loon, van W.K.P.; Zeeman, G.

2003-01-01

The anaerobic digestion of cow manure has a higher destruction of pathogens and weed seeds under thermophilic conditions compared to mesophilic conditions. To maintain such conditions, solar energy can be used. In this research, the consequences of the use of solar energy under Egyptian conditions

Saponification of fatty slaughterhouse wastes for enhancing anaerobic biodegradability.

Science.gov (United States)

Battimelli, Audrey; Carrère, Hélène; Delgenès, Jean-Philippe

2009-08-01

The thermochemical pretreatment by saponification of two kinds of fatty slaughterhouse waste--aeroflotation fats and flesh fats from animal carcasses--was studied in order to improve the waste's anaerobic degradation. The effect of an easily biodegradable compound, ethanol, on raw waste biodegradation was also examined. The aims of the study were to enhance the methanisation of fatty waste and also to show a link between biodegradability and bio-availability. The anaerobic digestion of raw waste, saponified waste and waste with a co-substrate was carried out in batch mode under mesophilic and thermophilic conditions. The results showed little increase in the total volume of biogas, indicating a good biodegradability of the raw wastes. Mean biogas volume reached 1200 mL/g VS which represented more than 90% of the maximal theoretical biogas potential. Raw fatty wastes were slowly biodegraded whereas pretreated wastes showed improved initial reaction kinetics, indicating a better initial bio-availability, particularly for mesophilic runs. The effects observed for raw wastes with ethanol as co-substrate depended on the process temperature: in mesophilic conditions, an initial improvement was observed whereas in thermophilic conditions a significant decrease in biodegradability was observed.

Discovery of Microorganisms and Enzymes Involved in High-Solids Decomposition of Rice Straw Using Metagenomic Analyses

Science.gov (United States)

D’haeseleer, Patrik; Khudyakov, Jane; Burd, Helcio; Hadi, Masood; Simmons, Blake A.; Singer, Steven W.; Thelen, Michael P.; VanderGheynst, Jean S.

2013-01-01

High-solids incubations were performed to enrich for microbial communities and enzymes that decompose rice straw under mesophilic (35°C) and thermophilic (55°C) conditions. Thermophilic enrichments yielded a community that was 7.5 times more metabolically active on rice straw than mesophilic enrichments. Extracted xylanase and endoglucanse activities were also 2.6 and 13.4 times greater, respectively, for thermophilic enrichments. Metagenome sequencing was performed on enriched communities to determine community composition and mine for genes encoding lignocellulolytic enzymes. Proteobacteria were found to dominate the mesophilic community while Actinobacteria were most abundant in the thermophilic community. Analysis of protein family representation in each metagenome indicated that cellobiohydrolases containing carbohydrate binding module 2 (CBM2) were significantly overrepresented in the thermophilic community. Micromonospora, a member of Actinobacteria, primarily housed these genes in the thermophilic community. In light of these findings, Micromonospora and other closely related Actinobacteria genera appear to be promising sources of thermophilic lignocellulolytic enzymes for rice straw deconstruction under high-solids conditions. Furthermore, these discoveries warrant future research to determine if exoglucanases with CBM2 represent thermostable enzymes tolerant to the process conditions expected to be encountered during industrial biofuel production. PMID:24205054

Discovery of microorganisms and enzymes involved in high-solids decomposition of rice straw using metagenomic analyses.

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Amitha P Reddy

Full Text Available High-solids incubations were performed to enrich for microbial communities and enzymes that decompose rice straw under mesophilic (35°C and thermophilic (55°C conditions. Thermophilic enrichments yielded a community that was 7.5 times more metabolically active on rice straw than mesophilic enrichments. Extracted xylanase and endoglucanse activities were also 2.6 and 13.4 times greater, respectively, for thermophilic enrichments. Metagenome sequencing was performed on enriched communities to determine community composition and mine for genes encoding lignocellulolytic enzymes. Proteobacteria were found to dominate the mesophilic community while Actinobacteria were most abundant in the thermophilic community. Analysis of protein family representation in each metagenome indicated that cellobiohydrolases containing carbohydrate binding module 2 (CBM2 were significantly overrepresented in the thermophilic community. Micromonospora, a member of Actinobacteria, primarily housed these genes in the thermophilic community. In light of these findings, Micromonospora and other closely related Actinobacteria genera appear to be promising sources of thermophilic lignocellulolytic enzymes for rice straw deconstruction under high-solids conditions. Furthermore, these discoveries warrant future research to determine if exoglucanases with CBM2 represent thermostable enzymes tolerant to the process conditions expected to be encountered during industrial biofuel production.

Financial appraisal of wet mesophilic AD technology as a renewable energy and waste management technology

International Nuclear Information System (INIS)

Dolan, T.; Cook, M.B.; Angus, A.J.

2011-01-01

Anaerobic digestion (AD) has the potential to support diversion of organic waste from landfill and increase renewable energy production. However, diffusion of this technology has been uneven, with countries such as Germany and Sweden taking the lead, but limited diffusion in other countries such as the UK. In this context, this study explores the financial viability of AD in the UK to offer reasons why it has not been more widely used. This paper presents a model that calculates the Internal Rate of Return (IRR) on a twenty year investment in a 30,000 tonnes per annum wet mesophilic AD plant in the UK for the treatment of source separated organic waste, which is judged to be a suitable technology for the UK climate. The model evaluates the financial significance of the different alternative energy outputs from this AD plant and the resulting economic subsidies paid for renewable energy. Results show that renewable electricity and renewable heat sales supported by renewable electricity and renewable heat tariffs generates the greatest IRR (31.26%). All other uses of biogas generate an IRR in excess of 15%, and are judged to be a financially viable investment. Sensitivity analysis highlights the financial significance of: economic incentive payments and a waste management gate fee; and demonstrates that the fate of the digestate by-product is a source of financial uncertainty for AD investors. - Research highlights: → Diffusion of AD technology is less rapid in the UK than other EU countries. → UK AD is financially viable if the energy output is supported by government subsidy. → Sensitivity analysis highlights the financial need for a waste management gate fee. → Digestate by-product creates a significant financial uncertainty for AD investors.

Financial appraisal of wet mesophilic AD technology as a renewable energy and waste management technology

Energy Technology Data Exchange (ETDEWEB)

Dolan, T. [School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL (United Kingdom); Cook, M.B. [Design Group, Department of Design, Development, Environment and Materials, Open University, Walton Hall, Milton Keynes, Bucks (United Kingdom); Angus, A.J., E-mail: a.angus@cranfield.ac.uk [School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL (United Kingdom)

2011-06-01

Anaerobic digestion (AD) has the potential to support diversion of organic waste from landfill and increase renewable energy production. However, diffusion of this technology has been uneven, with countries such as Germany and Sweden taking the lead, but limited diffusion in other countries such as the UK. In this context, this study explores the financial viability of AD in the UK to offer reasons why it has not been more widely used. This paper presents a model that calculates the Internal Rate of Return (IRR) on a twenty year investment in a 30,000 tonnes per annum wet mesophilic AD plant in the UK for the treatment of source separated organic waste, which is judged to be a suitable technology for the UK climate. The model evaluates the financial significance of the different alternative energy outputs from this AD plant and the resulting economic subsidies paid for renewable energy. Results show that renewable electricity and renewable heat sales supported by renewable electricity and renewable heat tariffs generates the greatest IRR (31.26%). All other uses of biogas generate an IRR in excess of 15%, and are judged to be a financially viable investment. Sensitivity analysis highlights the financial significance of: economic incentive payments and a waste management gate fee; and demonstrates that the fate of the digestate by-product is a source of financial uncertainty for AD investors. - Research highlights: {yields} Diffusion of AD technology is less rapid in the UK than other EU countries. {yields} UK AD is financially viable if the energy output is supported by government subsidy. {yields} Sensitivity analysis highlights the financial need for a waste management gate fee. {yields} Digestate by-product creates a significant financial uncertainty for AD investors.

Transformation of benzalkonium chloride under nitrate reducing conditions.

Science.gov (United States)

Tezel, Ulas; Pavlostathis, Spyros G

2009-03-01

The effect and transformation potential of benzalkonium chlorides (BAC) under nitrate reducing conditions were investigated at concentrations up to 100 mg/L in batch assays using a mixed, mesophilic (35 degrees C) methanogenic culture. Glucose was used as the carbon and energy source and the initial nitrate concentration was 70 mg N/L Dissimilatory nitrate reduction to ammonia (DNRA) and to dinitrogen (DNRN) were observed at BAC concentrations up to 25 mg/L At and above 50 mg BAC/L, DNRA was inhibited and DNRN was incomplete resulting in accumulation of nitrous oxide. Long-term inhibition of methanogenesis and accumulation of volatile fatty acids were observed at and above 50 mg BAC/L Over 99% of the added BAC was recovered from all cultures except the one amended with 100 mg BAC/L where 37% of the initially added BAC was transformed during the 100 day incubation period. Abiotic and biotic assays performed with 100 mg/L of BAC and 5 mM (in the liquid phase) of either nitrate, nitrite, or nitric oxide demonstrated that BAC transformation was abiotic and followed the modified Hofmann degradation pathway, i.e., bimolecular nucleophilic substitution with nitrite. Alkyl dimethyl amines (tertiary amines) were produced at equamolar levels to BAC transformed, but were not further degraded. This is the first report demonstrating the transformation of BAC under nitrate reducing conditions and elucidating the BAC transformation pathway.

Changes in the microbiological quality of mangrove oysters (Crassostrea brasiliana) during different storage conditions.

Science.gov (United States)

Montanhini, Maike Taís Maziero; Montanhini Neto, Roberto

2015-01-01

This study aimed to determine the effect of temperature and period of postharvest storage on the microbiological quality and shelf life of raw mangrove oysters, Crassostrea brasiliana. A total of 150 dozen oysters were collected directly from the points of extraction or cultivation in southern Brazil, and in the laboratory, they were stored raw at 5, 10, 15, 20, and 25°C for 1, 4, 8, 11, and 15 days. On each of these days, the oysters were subjected to microbiological analyses of aerobic mesophilic count, total coliforms, enterococci, Escherichia coli, Staphylococcus aureus, and Salmonella. None of the tested samples under any storage condition showed contamination levels above those allowed by Brazilian legislation for E. coli, S. aureus, and Salmonella, and there was no change (P > 0.05) in the counts of these microorganisms due to the temperature and/or period of oyster storage. Counts of enterococci and total coliforms showed a tendency to increase (P mangrove oysters remain in safe microbiological conditions for consumption up to 8 days after harvesting, regardless of temperature, and their shelf life may be extended to 15 days if they are stored at temperatures not exceeding 15°C.

An organic solvent-, detergent-, and thermo-stable alkaline protease from the mesophilic, organic solvent-tolerant Bacillus licheniformis 3C5.

Science.gov (United States)

Rachadech, W; Navacharoen, A; Ruangsit, W; Pongtharangkul, T; Vangnai, A S

2010-01-01

Bacillus licheniformis 3C5, isolated as mesophilic bacterium, exhibited tolerance towards a wide range of non-polar and polar organic solvents at 45 degrees C. It produced an extracellular organic solvent-stable protease with an apparent molecular mass of approximately 32 kDa. The inhibitory effect of PMSF and EDTA suggested it is likely to be an alkaline serine protease. The protease was active over abroad range of temperatures (45-70 degrees C) and pH (8-10) range with an optimum activity at pH 10 and 65 degrees C. It was comparatively stable in the presence ofa relatively high concentration (35% (v/v)) of organic solvents and various types of detergents even at a relatively high temperature (45 degrees C). The protease production by B. licheniformis 3C5 was growth-dependent. The optimization of carbon and nitrogen sources for cell growth and protease production revealed that yeast extract was an important medium component to support both cell growth and the protease production. The overall properties of the protease produced by B. licheniformis 3C5 suggested that this thermo-stable, solvent-stable, detergent-stable alkaline protease is a promising potential biocatalyst for industrial and environmental applications.

In vivo photosystem I reduction in thermophilic and mesophilic cyanobacteria: The thermal resistance of the process is limited by factors other than the unfolding of the partners

International Nuclear Information System (INIS)

Duran, Raul V.; Hervas, Manuel; Rosa, Miguel A. de la; Navarro, Jose A.

2005-01-01

Photosystem I reduction by plastocyanin and cytochrome c 6 in cyanobacteria has been extensively studied in vitro, but much less information is provided on this process inside the cell. Here, we report an analysis of the electron transfer from both plastocyanin and cytochrome c 6 to photosystem I in intact cells of several cyanobacterial species, including a comparative study of the temperature effect in mesophilic and thermophilic organisms. Our data show that cytochrome c 6 reduces photosystem I by following a reaction mechanism involving complex formation, whereas the copper-protein follows a simpler collisional mechanism. These results contrast with previous kinetic studies in vitro. The effect of temperature on photosystem I reduction leads us to conclude that the thermal resistance of this process is determined by factors other than the proper stability of the protein partners

Genome sequence of a mesophilic hydrogenotrophic methanogen Methanocella paludicola, the first cultivated representative of the order Methanocellales.

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Sanae Sakai

Full Text Available We report complete genome sequence of a mesophilic hydrogenotrophic methanogen Methanocella paludicola, the first cultured representative of the order Methanocellales once recognized as an uncultured key archaeal group for methane emission in rice fields. The genome sequence of M. paludicola consists of a single circular chromosome of 2,957,635 bp containing 3004 protein-coding sequences (CDS. Genes for most of the functions known in the methanogenic archaea were identified, e.g. a full complement of hydrogenases and methanogenesis enzymes. The mixotrophic growth of M. paludicola was clarified by the genomic characterization and re-examined by the subsequent growth experiments. Comparative genome analysis with the previously reported genome sequence of RC-I(MRE50, which was metagenomically reconstructed, demonstrated that about 70% of M. paludicola CDSs were genetically related with RC-I(MRE50 CDSs. These CDSs included the genes involved in hydrogenotrophic methane production, incomplete TCA cycle, assimilatory sulfate reduction and so on. However, the genetic components for the carbon and nitrogen fixation and antioxidant system were different between the two Methanocellales genomes. The difference is likely associated with the physiological variability between M. paludicola and RC-I(MRE50, further suggesting the genomic and physiological diversity of the Methanocellales methanogens. Comparative genome analysis among the previously determined methanogen genomes points to the genome-wide relatedness of the Methanocellales methanogens to the orders Methanosarcinales and Methanomicrobiales methanogens in terms of the genetic repertoire. Meanwhile, the unique evolutionary history of the Methanocellales methanogens is also traced in an aspect by the comparative genome analysis among the methanogens.

Contagem de bactérias mesófilas aeróbias e características físico-químicas do leite humano armazenado em embalagem de polietileno / Aerobic mesophilic bacteria count and physical and chemical characteristics of breast milk stored in polyethylene packages

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Mayara de Simas Mesquita

2016-08-01

quality of pasteurized human milk. Dornic acidity, energy, fat, lactose and proteins in raw and pasteurized human milk were taken before and after 15-day storage in the packages. The influence of the package was analyzed using ANOVA. Values of p < 0.05 were considered significant. Results: The occurrence of mesophiles in pasteurized human milk ranged from 0 to 12%. The raw and pasteurized human milk had < 8oD acidity, indicating good handling practices and appropriate sanitary hygienic conditions. The fat, energy, protein and lactose of human milk in the polyethylene bag and glass were averaged: 3.2–3,5%, 65–68 kcal/dL, 6.0% and 0.9–1.3%, respectively. No significant differences were observed in the physicochemical characteristics of human milk among the packages. Conclusion: Polyethylene packaging for human milk storage can be a viable alternative to milk banks.

Modeling the Growth of Epiphytic Bacteria on Kale Treated by Thermosonication Combined with Slightly Acidic Electrolyzed Water and Stored under Dynamic Temperature Conditions.

Science.gov (United States)

Mansur, Ahmad Rois; Oh, Deog-Hwan

2016-08-01

The growth of epiphytic bacteria (aerobic mesophilic bacteria or Pseudomonas spp.) on kale was modeled isothermally and validated under dynamic storage temperatures. Each bacterial count on kale stored at isothermal conditions (4 to 25 °C) was recorded. The results show that maximum growth rate (μmax ) of both epiphytic bacteria increased and lag time (λ) decreased with increasing temperature (P 0.97), whereas lower R(2) > 0.86 and R(2) > 0.87 was observed for the λ and Nmax , respectively. The overall predictions of both epiphytic bacterial growths under nonisothermal conditions with temperature abuse of 15 °C agreed with the observed data, whereas those with temperature abuse of 25 °C were greatly overestimated. The appropriate parameter q0 (physiological state of cells), therefore, was adjusted by a trial and error to fit the model. This study demonstrates that the developed model was able to predict accurately epiphytic bacterial growth on kale stored under nonisothermal conditions particularly those with low temperature abuse of 15 °C. © 2016 Institute of Food Technologists®

Effect of temperature on selenium removal from wastewater by UASB reactors.

Science.gov (United States)

Dessì, Paolo; Jain, Rohan; Singh, Satyendra; Seder-Colomina, Marina; van Hullebusch, Eric D; Rene, Eldon R; Ahammad, Shaikh Ziauddin; Carucci, Alessandra; Lens, Piet N L

2016-05-01

The effect of temperature on selenium (Se) removal by upflow anaerobic sludge blanket (UASB) reactors treating selenate and nitrate containing wastewater was investigated by comparing the performance of a thermophilic (55 °C) versus a mesophilic (30 °C) UASB reactor. When only selenate (50 μM) was fed to the UASB reactors (pH 7.3; hydraulic retention time 8 h) with excess electron donor (lactate at 1.38 mM corresponding to an organic loading rate of 0.5 g COD L(-1) d(-1)), the thermophilic UASB reactor achieved a higher total Se removal efficiency (94.4 ± 2.4%) than the mesophilic UASB reactor (82.0 ± 3.8%). When 5000 μM nitrate was further added to the influent, total Se removal was again better under thermophilic (70.1 ± 6.6%) when compared to mesophilic (43.6 ± 8.8%) conditions. The higher total effluent Se concentration in the mesophilic UASB reactor was due to the higher concentrations of biogenic elemental Se nanoparticles (BioSeNPs). The shape of the BioSeNPs observed in both UASB reactors was different: nanospheres and nanorods, respectively, in the mesophilic and thermophilic UASB reactors. Microbial community analysis showed the presence of selenate respirers as well as denitrifying microorganisms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microbiota dynamics related to environmental conditions during the fermentative production of Fen-Daqu, a Chinese industrial fermentation starter

NARCIS (Netherlands)

Zheng, X.; Yan, Z.; Nout, M.J.R.; Smid, E.J.; Zwietering, M.H.; Boekhout, T.; Han, J.S.; Han, B.

2014-01-01

Chinese Daqu is used as a starter for liquor and vinegar fermentations. It is produced by solid state fermentation of cereal–pulse mixtures. A succession of fungi, lactic acid bacteria and Bacillus spp. was observed during the production of Daqu. Mesophilic bacteria followed by fungi, dominated the

Microbiota dynamics related to environmental conditions during the fermentative production of Fen-Daqu, a Chinese industrial fermentation starter

NARCIS (Netherlands)

Zheng, Xiao-Wei; Yan, Zheng; Nout, M J Robert; Smid, Eddy J; Zwietering, Marcel H; Boekhout, Teun; Han, Jian-Shu; Han, Bei-Zhong

2014-01-01

Chinese Daqu is used as a starter for liquor and vinegar fermentations. It is produced by solid state fermentation of cereal-pulse mixtures. A succession of fungi, lactic acid bacteria and Bacillus spp. was observed during the production of Daqu. Mesophilic bacteria followed by fungi, dominated the

Supplementary Material for: Lignocellulose-derived thin stillage composition and efficient biological treatment with a high-rate hybrid anaerobic bioreactor system

KAUST Repository

Oosterkamp, Margreet

2016-01-01

Abstract Background This study aims to chemically characterize thin stillage derived from lignocellulosic biomass distillation residues in terms of organic strength, nutrient, and mineral content. The feasibility of performing anaerobic digestion on these stillages at mesophilic (40 °C) and thermophilic (55 °C) temperatures to produce methane was demonstrated. The microbial communities involved were further characterized. Results Energy and sugar cane stillage have a high chemical oxygen demand (COD of 43 and 30 g/L, respectively) and low pH (pH 4.3). Furthermore, the acetate concentration in sugar cane stillage was high (45 mM) but was not detected in energy cane stillage. There was also a high amount of lactate in both types of stillage (35–37 mM). The amount of sugars was 200 times higher in energy cane stillage compared to sugar cane stillage. Although there was a high concentration of sulfate (18 and 23 mM in sugar and energy cane stillage, respectively), both thin stillages were efficiently digested anaerobically with high COD removal under mesophilic and thermophilic temperature conditions and with an organic loading rate of 15–21 g COD/L/d. The methane production rate was 0.2 L/g COD, with a methane percentage of 60 and 64, and 92 and 94 % soluble COD removed, respectively, by the mesophilic and thermophilic reactors. Although both treatment processes were equally efficient, there were different microbial communities involved possibly arising from the differences in the composition of energy cane and sugar cane stillage. There was more acetic acid in sugar cane stillage which may have promoted the occurrence of aceticlastic methanogens to perform a direct conversion of acetate to methane in reactors treating sugar cane stillage. Conclusions Results showed that thin stillage contains easily degradable compounds suitable for anaerobic digestion and that hybrid reactors can efficiently convert thin stillage to methane under mesophilic and

Apport des analyses isotopiques et moléculaires pour la caractérisation des communautés fonctionnelles et des voies métaboliques au cours de la méthanogenèse dans des boues d'épuration

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Driss Limam, R.

2015-01-01

Full Text Available Characterization of functional communities and metabolic pathways during methanogenesis in wastewater sludge by isotopic and molecular analysis. Description of the subject. Investigation of the relationships between methanogenic community and metabolic pathway dynamics during methanogenesis. Objectives. The objective was to use an isotopic approach coupled with molecular analysis to identify metabolisms and to understand the dynamics of Archaea under different temperature conditions. Method. Sludge was incubated anaerobically under mesophilic and thermophilic conditions. Biogas production was monitored, together with stable isotopic signatures of produced CH4 and CO2. Results. Isotopic signature values for CH4 indicated a change in methanogenic metabolism with time and temperature. CH4 was predominantly produced from H2/CO2 and acetoclastic metabolism at the beginning of the mesophilic incubations and after acetate injection. A progressive shift towards an acetoclastic metabolism was observed at the end of mesophilic incubations. This period was associated with stability within archaeal communities as monitored by automated ribosomal intergenic spacer analysis (ARISA and FISH with oligonucleotidic probes targeting specifically the Archaea 16S rRNA gene. At the beginning of the thermophilic incubations and after acetate injection, methane was generated mostly from H2/CO2. At the end of the thermophilic incubations, an acetoclastic metabolism was observed and intergenic spacer analysis (ARISA and FISH showed important shifts in archaeal communities. Conclusions. Isotopic methods coupled with molecular analyses enabled us to better understand methanogenesis and the involvement of archaeal populations, which varied according to temperature. We also observed a preadaptation of archaeal communities in thermophilic conditions, which could be due to the fact that mesophilic microorganisms were progressively eliminated during the thermophilic incubation

Anaerobic digestion of macroalgal biomass and sediments sourced from the Orbetello lagoon, Italy

International Nuclear Information System (INIS)

Migliore, G.; Alisi, C.; Sprocati, A.R.; Massi, E.; Ciccoli, R.; Lenzi, M.; Wang, A.; Cremisini, C.

2012-01-01

The anaerobic digestion of marine macroalgae biomass could meet two currently important needs, the mitigation of the eutrophication effects and the production of renewable energy. Because of the abundance of seaweed biomass its conversion can be highly desirable and convenient, mostly for countries with long coastlines or eutrophic environments. The aim of the present work is to carry out an exploratory study of biogas production from macroalgal biomass collected from the Orbetello lagoon (Tuscany, Italy) by solely exploiting the intrinsic degradation potential of the ecosystem. A fresh algae mix and sediments has been used, as both feed and inoculum of an anaerobic digestion process under psychro-mesophilic, mesophilic and thermophilic conditions, in batch reactors, without any washing and drying treatment. The presence of sediment proved to be crucial in order to achieve a good methane yield (methane yield of 380 dm 3 kg −1 VS added ) comparable with literature data obtained through different approaches. The results gave evidence that such an approach will have to be considered when planning a selective anaerobic digestion of macroalgae that could be useful in local applications for coasts and eutrophic lagoons affected by seasonal or frequent algal blooms. -- Highlights: ► Biogas production from macroalgal biomass with minimal energy input is proposed. ► Psychro-mesophilic, mesophilic and thermophilic conditions were compared. ► Highly adapted bacterial pool was crucial to achieve a good methane yield. ► The applied process exploits the intrinsic degradation potential of the ecosystem.

Investigation of the bacteriophage community in induced lysates of undefined mesophilic mixed-strain DL-cultures using classical and metagenomic approaches.

Science.gov (United States)

Muhammed, Musemma K; Olsen, Mette L; Kot, Witold; Neve, Horst; Castro-Mejía, Josué L; Janzen, Thomas; Hansen, Lars H; Nielsen, Dennis S; Sørensen, Søren J; Heller, Knut J; Vogensen, Finn K

2018-05-02

To investigate the notion that starter cultures can be a reservoir of bacteriophages (phages) in the dairy environment, strains of three DL-starters (undefined mesophilic mixed-strain starters containing Lactococcus lactis subsp. lactis biovar. diacetylactis and Leuconostoc species) were selected and induced by mitomycin C, and the whole starters were induced spontaneously as well as by mitomycin C. Frequency of induction of 17%, 26% and 12% was estimated among the isolates of the three starters, with majority of the induced phages mostly showing morphological similarity to known P335 phages, and with a fraction of them showing atypical features. Sequences of P335 quasi-species phages were found to be the most frequent entities in almost all metaviromes derived from the induced lysates. However, sequences of Sk1virus phages (previously 936 phages) were emerged as the predominant entities following spontaneous induction of one of the starters, suggesting a phage-carrier state. Sequences of other phages such as 949, 1706, C2virus (previously c2 phages) and Leuconostoc species could also be observed but with a lower relative frequency. Taken together, the majority of the P335 quasi-species phages could represent the induced viral community of the starters and the remaining phage groups mainly represent the background ambient viral community. Copyright © 2018 Elsevier B.V. All rights reserved.

Impacts of zero valent iron, natural zeolite and Dnase on the fate of antibiotic resistance genes during thermophilic and mesophilic anaerobic digestion of swine manure.

Science.gov (United States)

Zhang, Junya; Sui, Qianwen; Zhong, Hui; Meng, Xiaoshan; Wang, Ziyue; Wang, Yawei; Wei, Yuansong

2018-06-01

This study investigated the fate of antibiotic resistance genes (ARGs) during mesophilic (mAD) and thermophilic digestion (tAD) of swine manure through zero valent iron (ZVI), natural zeolite and Dnase addition. Changes of microbial community, intI1, heavy metal resistance genes (MRGs) and virulence factors (VFs) were followed to clarify the influencing factors to ARGs reduction. Results showed that AD could realize ARGs reduction with tAD superior to mAD, and ZVI and natural zeolite could further enhance the reduction, especially for natural zeolite addition at mAD. The reduction efficiency of the relative abundance of ARGs was increased by 33.3% and 138.5% after ZVI and natural zeolite addition, respectively, but Dnase deteriorated ARGs reduction at mAD. Most of ARGs could be reduced effectively except sulII and tetM. Network analysis and partial redundancy analysis indicated that co-occurrence of MRGs followed by microbial community contributed the most to the variation of ARGs fate among treatments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Leaching behaviour of hazardous waste under the impact of different ambient conditions.

Science.gov (United States)

Pecorini, Isabella; Baldi, Francesco; Bacchi, Donata; Carnevale, Ennio Antonio; Corti, Andrea

2017-05-01

The overall objective of this study is to provide an improved basis for the assessment of the leaching behaviour of waste marked as hazardous partly stabilised (European waste catalogue code 19 03 04 ∗ ). Four samples of hazardous partly stabilised waste were subjected to two leaching tests: up-flow column tests and batch equilibrium tests. The research was carried out in two directions: the first aims at comparing the results of the two experimental setups while the second aims at assessing the impact of different ambient conditions on the leaching behaviour of waste. Concerning this latter objective the effect of mesophilic temperature, mechanical constraints and acid environment were tested through column percolation tests. Results showed no significant differences between batch and column leaching test outcomes when comparing average concentrations calculated at a liquid to solid ratio of 10:1 l kg -1  TS. Among the tested ambient conditions, the presence of an acid environment (pH=4.5) accelerated the leaching process resulting in a higher cumulative released quantity measured on the majority of the investigated polluting substances. On the contrary, the effect of temperature and mechanical constraints seemed to not affect the process showing final contents even lower than values found for the standard test. This result was furthermore confirmed by the application of the principal component analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of winery waste and waste activated sludge: assessment of process feasibility.

Science.gov (United States)

Da Ros, C; Cavinato, C; Cecchi, F; Bolzonella, D

2014-01-01

In this study the anaerobic co-digestion of wine lees together with waste activated sludge in mesophilic and thermophilic conditions was tested at pilot scale. Three organic loading rates (OLRs 2.8, 3.3 and 4.5 kgCOD/m(3)d) and hydraulic retention times (HRTs 21, 19 and 16 days) were applied to the reactors, in order to evaluate the best operational conditions for the maximization of the biogas yields. The addition of lee to sludge determined a higher biogas production: the best yield obtained was 0.40 Nm(3)biogas/kgCODfed. Because of the high presence of soluble chemical oxygen demand (COD) and polyphenols in wine lees, the best results in terms of yields and process stability were obtained when applying the lowest of the three organic loading rates tested together with mesophilic conditions.

Bioleaching of a low grade sphalerite concentrate produced from flotation tailings

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Javad Mehrabani

2016-12-01

Full Text Available In this research work, the zinc extraction was investigated, using bioleaching process from a low grade zinc concentrate which was produced from the accumulated flotation tailings. Zinc content was initially upgraded to 11.97% by flotation process. Bioleaching experiments were designed and carried out by a mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirilium ferrooxidans, as well as a mixed moderate thermophile bacteria in the shake flasks. Effect of two types bacteria, indigenous bacteria accompany by concentrate sample, and added mixture of bacteria were evaluated. The term of indigenous bacteria refers to the bacteria which initially exist in the natural concentrate sample. The results showed that more than 87% and 94% of Zn was dissolved in the bioleaching condition of mesophile and moderate thermophile bacteria, respectively. Comparing bioleaching and leaching tests indicated that mesophile bacteria improved Zn extraction 36%, in which contribution of concentrate indigenous bacteria (test condition of non-inoculation and added mesophile mixed bacteria were equal to 34% and 66% of that improvement, respectively. In addition, moderate thermophile bacteria improved sphalerite leaching up to 38% in which contribution of concentrate indigenous bacteria and added moderate bacteria were about 50% separately.

Survival of Antibiotic Resistant Bacteria and Horizontal Gene Transfer Control Antibiotic Resistance Gene Content in Anaerobic Digesters.

Science.gov (United States)

Miller, Jennifer H; Novak, John T; Knocke, William R; Pruden, Amy

2016-01-01

Understanding fate of antibiotic resistant bacteria (ARB) vs. their antibiotic resistance genes (ARGs) during wastewater sludge treatment is critical in order to reduce the spread of antibiotic resistance through process optimization. Here, we spiked high concentrations of tetracycline-resistant bacteria, isolated from mesophilic (Iso M1-1-a Pseudomonas sp.) and thermophilic (Iso T10-a Bacillus sp.) anaerobic digested sludge, into batch digesters and monitored their fate by plate counts and quantitative polymerase chain reaction (QPCR) of their corresponding tetracycline ARGs. In batch studies, spiked ARB plate counts returned to baseline (thermophilic) or 1-log above baseline (mesophilic) while levels of the ARG present in the spiked isolate [tet(G)] remained high in mesophilic batch reactors. To compare results under semi-continuous flow conditions with natural influent variation, tet(O), tet(W), and sul1 ARGs, along with the intI1 integrase gene, were monitored over a 9-month period in the raw feed sludge and effluent sludge of lab-scale thermophilic and mesophilic anaerobic digesters. sul1 and intI1 in mesophilic and thermophilic digesters correlated positively (Spearman rho = 0.457-0.829, P < 0.05) with the raw feed sludge. There was no correlation in tet(O) or tet(W) ratios in raw sludge and mesophilic digested sludge or thermophilic digested sludge (Spearman rho = 0.130-0.486, P = 0.075-0.612). However, in the thermophilic digester, the tet(O) and tet(W) ratios remained consistently low over the entire monitoring period. We conclude that the influent sludge microbial composition can influence the ARG content of a digester, apparently as a result of differential survival or death of ARBs or horizontal gene transfer of genes between raw sludge ARBs and the digester microbial community. Notably, mesophilic digestion was more susceptible to ARG intrusion than thermophilic digestion, which may be attributed to a higher rate of ARB survival and/or horizontal gene

Milk processed by pulsed electric fields: evaluation of microbial quality, physicochemical characteristics, and selected nutrients at different storage conditions.

Science.gov (United States)

Bermúdez-Aguirre, Daniela; Fernández, Sulmer; Esquivel, Heracleo; Dunne, Patrick C; Barbosa-Cánovas, Gustavo V

2011-01-01

Pulsed electric fields (PEF) technology was used to pasteurize raw milk under selected treatments. Processing conditions were: temperature 20, 30, and 40 °C, electric field 30.76 to 53.84 kV/cm, and pulse numbers 12, 24, and 30 for skim milk (SM), and 12, 21, and 30 for whole milk (WM) (2 μs pulse width, monopolar). Physicochemical parameters (pH, electrical conductivity, density, color, solids nonfat [SNF]) and composition (protein and fat content) were measured after processing. Shelf life of SM and WM was assessed after processing at 46.15 kV/cm, combined with temperature (20 to 60 °C) and 30 pulses. Mesophilic and psychrophilic loads and pH were evaluated during storage at 4 and 21 °C. Results showed minor variations in physicochemical properties after processing. There was an interesting trend in SM in SNF, which decreased as treatment became stronger; similar behavior was observed for fat and protein, showing a 0.18% and 0.17% decrease, respectively, under the strongest conditions. Protein and fat content decreased in WM samples treated at 40 °C, showing a decrease in protein (0.11%), and an even higher decrease in fat content. During storage, PEF-treated milk samples showed higher stability at 4 °C with minor variations in pH; after 33 d, pH was higher than 6. However samples at 21 °C showed faster spoilage and pH dropped to 4 after 5 d. Growth of mesophilic bacteria was delayed in both milks after PEF processing, showing a 6- and 7-log cycles for SM and WM, respectively, after day 25 (4 °C); however, psychrophilic bacteria grew faster in both cases. Pulsed electric fields (PEF) technology in the pasteurization of liquid food products has shown positive results. Processing times can be reduced considerably, which in turn reduces the loss of nutrients and offers important savings in energy. PEF has been used successfully to pasteurize some liquid foods, but it is still not used commercially in milk pasteurization, although several trials have shown

Occurrence of Shewanella algae in Danish coastal water and effects of water temperature and culture conditions on its survival

DEFF Research Database (Denmark)

Gram, Lone; Bundvad, Anemone; Melchiorsen, Jette

1999-01-01

increased to 10(5) to 10(7) CFU/ml at room temperature. Most probable number analysis showed this result to be due to regrowth rather than resuscitation. It was hypothesized that S. algae would survive cold exposure better if in the biofilm state; however, culturable counts from S. algae biofilms decreased......The marine bacterium Shewanella algae, which was identified as the cause of human cases of bacteremia and ear infections in Denmark in the summers of 1994 and 1995, was detected in seawater only during the months (July, August, September, and October) when the water temperature was above 13 degrees...... C. The bacterium is a typical mesophilic organism, and model experiments were conducted to elucidate the fate of the organism under cold and nutrient-limited conditions. The culturable count of S. algae decreased rapidly from 10(7) CFU/ml to 10(1) CFU/ml in approximately 1 month when cells grown...

Effect of CaO2 addition on anaerobic digestion of waste activated sludge at different temperatures and the promotion of valuable carbon source production under ambient condition.

Science.gov (United States)

Ping, Qian; Lu, Xiao; Zheng, Ming; Li, Yongmei

2018-06-06

The effect of calcium peroxide (CaO 2 ) addition on anaerobic digestion (AD) of waste activated sludge (WAS) at different temperatures (20 °C, 35 °C, and 55 °C) were investigated. The results show that CaO 2 addition had significant positive effect on short-chain fatty acids (SCFAs) production under ambient and mesophilic conditions. Polysaccharides and proteins embedded in extracellular polymeric substances (EPS) were effectively released from inner fraction to outer fraction, and non-biodegradable humic-like substances were decreased while easily biodegradable tryptophan-like proteins increased. These effects were most remarkable under ambient conditions. However, CaO 2 addition was unfavorable to thermophilic AD because of high free ammonia concentrations and the accumulation of humic-like substances. Temperature showed a stronger effect than CaO 2 on microbial community structure, but CaO 2 addition was more effective than temperature in enhancing hydrolytic and acidifying microorganisms. Predictive functional profiling indicated that microbial hydrolysis, metabolism and acidification were promoted by CaO 2 under ambient conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Inhibitory effects on anaerobic digestion of swine manure

Energy Technology Data Exchange (ETDEWEB)

Cheung, P.W.S.; Zhou, H. [Univ. of Guelph, School of Engineering, Guelph, Ontario (Canada)]. E-mail: hzhou@uoguelph.ca; Hacker, R. [Univ. of Guelph, Dept. of Animal and Poultry Science, Guelph, Ontario (Canada)

2002-06-15

This paper presents a laboratory study using anaerobic digestion for swine manure under both mesophilic and thermophilic conditions, with emphasis on the effects of inhibitory chemicals on biogas production. A series of batch tests were conducted to examine the effects of various process parameters by varying temperature, pH, ammonia and hydrogen sulfide concentrations. As well, continuous anaerobic digestion tests were conducted using a completely stirred reactor system with a sludge retention time of 15 days. The results showed that at the initial stage, biogas was generated rapidly in the thermophilic reactor, but was more and more inhibited during the later stage with the presence of ammonia and hydrogen sulfide. In contrast, the biogas production was initially delayed in the mesophilic reactor but afterwards had an even higher total gas production. In order to take advantages of both temperature effects in each reactor, the dual-stage system that consists of a thermophilic reactor followed by a mesophilic reactor was suggested. (author)

Inhibitory effects on anaerobic digestion of swine manure

International Nuclear Information System (INIS)

Cheung, P.W.S.; Zhou, H.; Hacker, R.

2002-01-01

This paper presents a laboratory study using anaerobic digestion for swine manure under both mesophilic and thermophilic conditions, with emphasis on the effects of inhibitory chemicals on biogas production. A series of batch tests were conducted to examine the effects of various process parameters by varying temperature, pH, ammonia and hydrogen sulfide concentrations. As well, continuous anaerobic digestion tests were conducted using a completely stirred reactor system with a sludge retention time of 15 days. The results showed that at the initial stage, biogas was generated rapidly in the thermophilic reactor, but was more and more inhibited during the later stage with the presence of ammonia and hydrogen sulfide. In contrast, the biogas production was initially delayed in the mesophilic reactor but afterwards had an even higher total gas production. In order to take advantages of both temperature effects in each reactor, the dual-stage system that consists of a thermophilic reactor followed by a mesophilic reactor was suggested. (author)

The effect of temperature on the fatty acids and isozymes of a psychrotrophic and two mesophilic species of Xenorhabdus, a bacterial symbiont of entomopathogenic nematodes

Energy Technology Data Exchange (ETDEWEB)

He, H. [Wisconsin Univ., Dept. of Biological Sciences, Milwaukee, WI (United States); Gordon, R. [Prince Edward Island Univ., Dept. of Biology, Charlottetown, PE (Canada); Gow, J. A. [Memorial University of Newfoundland, St. John' s NF (Canada)

2001-05-01

Generation times relative to temperature were determined for four strains of Xenorhabdus bacteria that represented three geographically distinct species in order to study the capacity of these bacteria to adapt to changes in temperature, as shown by changes in fatty acid composition. Species of the genus Xenorhabdus are carried in the gut of non-feeding infective juvenile nematodes where they release antibacterial and antifungal compounds, to create a non-competitive environment for nematode and bacterial growth. One of the species investigated was psychotropic (i.e. thriving at low temperatures), the other two mesophilic (i.e. growing at moderate temperatures). Results showed that as temperatures declined, proportions of two of the major fatty acids increased significantly in all strains, while the proportion of the prevalent fatty acid (palmitic acid) decreased. Certain other fatty acids decreased with declining temperatures in all strains. The synthesis of isozymes in response to changing temperatures was also investigated. Results showed a broad capacity for physiological temperature adaptation among strains of different climatic origin. It is suggested that these results support the proposition that entomopathogenic bacteria associated with nematodes adjust to temperature changes physiologically by altering the synthesis of isozymes. 36 refs.,6 tabs.

Structural comparison of tRNA m1A58 methyltransferases revealed different molecular strategies to maintain their oligomeric architecture under extreme conditions

Directory of Open Access Journals (Sweden)

Guelorget Amandine

2011-12-01

Full Text Available Abstract Background tRNA m1A58 methyltransferases (TrmI catalyze the transfer of a methyl group from S-adenosyl-L-methionine to nitrogen 1 of adenine 58 in the T-loop of tRNAs from all three domains of life. The m1A58 modification has been shown to be essential for cell growth in yeast and for adaptation to high temperatures in thermophilic organisms. These enzymes were shown to be active as tetramers. The crystal structures of five TrmIs from hyperthermophilic archaea and thermophilic or mesophilic bacteria have previously been determined, the optimal growth temperature of these organisms ranging from 37°C to 100°C. All TrmIs are assembled as tetramers formed by dimers of tightly assembled dimers. Results In this study, we present a comparative structural analysis of these TrmIs, which highlights factors that allow them to function over a large range of temperature. The monomers of the five enzymes are structurally highly similar, but the inter-monomer contacts differ strongly. Our analysis shows that bacterial enzymes from thermophilic organisms display additional intermolecular ionic interactions across the dimer interfaces, whereas hyperthermophilic enzymes present additional hydrophobic contacts. Moreover, as an alternative to two bidentate ionic interactions that stabilize the tetrameric interface in all other TrmI proteins, the tetramer of the archaeal P. abyssi enzyme is strengthened by four intersubunit disulfide bridges. Conclusions The availability of crystal structures of TrmIs from mesophilic, thermophilic or hyperthermophilic organisms allows a detailed analysis of the architecture of this protein family. Our structural comparisons provide insight into the different molecular strategies used to achieve the tetrameric organization in order to maintain the enzyme activity under extreme conditions.

Comparison of CSTR and UASB reactor configuration for the treatment of sulfate rich wastewaters under acidifying conditions

NARCIS (Netherlands)

Lopes, S.I.C.; Dreissen, C.; Capela, M.I.; Lens, P.N.L.

2008-01-01

The effects of lowering the operational pH from 6 to 5 on mesophilic (30 degrees C) sulfate reduction during the acidification of sucrose at an organic loading rate of 5 gCOD(1(reactor)d)(-1) and at a COD/SO42- ratio of 4 were evaluated in a CSTR and in a UASB reactor. The HRT was 24 h and 10 h,

Bioleaching of a low grade sphalerite concentrate produced from tailings flotation

International Nuclear Information System (INIS)

Mehrabani, J. V.; Shafaei, S. Z.; Noaparast, M.; Mousavi, S. M.

2016-01-01

In this research, the zinc extraction from a low grade zinc concentrate produced from the accumulated flotation tailings was investigated using the bio leaching process. Zinc content was initially upgraded to 11.97% through flotation process. Bio leaching experiments were designed and carried out by a mixed culture of Acidithiobacillus ferro oxidans, Acidithiobacillus thio oxidans, Leptospirilium ferro oxidans, as well as a mixed moderate thermophile bacteria in the shake flasks. The effect of two bacteria types, the indigenous bacteria accompanied by concentrate sample and added mixture of bacteria, were evaluated. The term of indigenous bacteria refers to the bacteria which initially exists in the natural concentrate sample. The results showed that more than 87% and 94% of Zn was dissolved in the bio leaching condition of mesophile and moderate thermophile bacteria, respectively. Comparing the bio leaching and leaching tests indicate that mesophile bacteria improves the Zn extraction by 36%, in which the contribution of concentrate indigenous bacteria (test condition of non-inoculation) and added mesophile mixed bacteria were equal to 34% and 66%, respectively. In addition, moderate thermophile bacteria improves the sphalerite leaching up to 38% in which contribution of the concentrate indigenous bacteria and added moderate thermophile bacteria were about 50% separately.

Factors controlling pathogen destruction during anaerobic digestion of biowastes

International Nuclear Information System (INIS)

Smith, S.R.; Lang, N.L.; Cheung, K.H.M.; Spanoudaki, K.

2005-01-01

Anaerobic digestion is the principal method of stabilising biosolids from urban wastewater treatment in the UK, and it also has application for the treatment of other types of biowaste. Increasing awareness of the potential risks to human and animal health from environmental sources of pathogens has focused attention on the efficacy of waste treatment processes at destroying pathogenic microorganisms in biowastes recycled to agricultural land. The degree of disinfection achieved by a particular anaerobic digester is influenced by a variety of interacting operational variables and conditions, which can often deviate from the ideal. Experimental investigations demonstrate that Escherichia coli and Salmonella spp. are not damaged by mesophilic temperatures, whereas rapid inactivation occurs by thermophilic digestion. A hydraulic, biokinetic and thermodynamic model of pathogen inactivation during anaerobic digestion showed that a 2 log 10 reduction in E. coli (the minimum removal required for agricultural use of conventionally treated biosolids) is likely to challenge most conventional mesophilic digesters, unless strict maintenance and management practices are adopted to minimise dead zones and by-pass flow. Efficient mixing and organic matter stabilisation are the main factors controlling the rate of inactivation under mesophilic conditions and not a direct effect of temperature per se on pathogenic organisms

Correlation between antibiotic and biocide resistance in mesophilic and psychrotrophic Pseudomonas spp. isolated from slaughterhouse surfaces throughout meat chain production.

Science.gov (United States)

Lavilla Lerma, Leyre; Benomar, Nabil; Casado Muñoz, María del Carmen; Gálvez, Antonio; Abriouel, Hikmate

2015-10-01

The aim of this study was to evaluate biocide susceptibility in mesophilic and psychrotrophic pseudomonads isolated from surfaces of a goat and lamb slaughterhouse, which was representative of the region. To determine biocide resistance in pseudomonads, we determined for the first time the epidemiological cut-off values (ECOFFs) of benzalkonium, cetrimide, chlorhexidine, hexachlorophene, P3 oxonia, polyhexamethylene guanidine hydrochloride (PHMG), topax 66 and triclosan being generally very similar in different Pseudomonas spp. with some exceptions. Thus, resistance of pseudomonads was mainly shown to triclosan, and in lesser extent to cetrimide and benzalkonium chloride depending on the species, however they were highly susceptible to industrial formulations of biocides. By means of statistical analysis, positive correlations between antibiotics, biocides and both antimicrobials in pseudomonads were detected suggesting a co- or cross resistance between different antimicrobials in goat and lamb slaughterhouse environment. Cross-resistance between biocides and antibiotics in pseudomonads were especially detected between PHMG or triclosan and different antibiotics depending on the biocide and the population type. Thus, the use of those biocides as disinfectant in slaughterhouse zones must be carefully evaluated because of the selection pressure effect of antimicrobials on the emergence of resistant bacteria which could be spread to the consumer. It is noteworthy that specific industrial formulations such as topax 66 and oxonia P3 showed few correlations with antibiotics (none or 1-2 antibiotics) which should be taken into consideration for disinfection practices in goat and lamb slaughterhouse. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anaerobic digestion as final step of a cellulosic ethanol biorefinery:

DEFF Research Database (Denmark)

Uellendahl, Hinrich; Ahring, Birgitte Kiær

2010-01-01

) and mesophilic (388C) operation of the UASB reactor was investigated. At an OLR of 3.5 kg- VS/(m3 day) a methane yield of 340 L/kg-VS was achieved for thermophilic operation (538C) while 270 L/kg-VS was obtained under mesophilic conditions (388C). For loading rates higher than 5 kg-VS/(m3 day) the methane yields...... of suspended matter reduced the degradation efficiency. The retention time of the anaerobic system could be reduced from 70 to 7 h by additional removal of suspended matter by clarification. Implementation of the biogas production from the fermentation effluent accounted for about 30% higher carbon utilization...

Growth media in anaerobic fermentative processes: The underestimated potential of thermophilic fermentation and anaerobic digestion.

Science.gov (United States)

Hendriks, A T W M; van Lier, J B; de Kreuk, M K

Fermentation and anaerobic digestion of organic waste and wastewater is broadly studied and applied. Despite widely available results and data for these processes, comparison of the generated results in literature is difficult. Not only due to the used variety of process conditions, but also because of the many different growth media that are used. Composition of growth media can influence biogas production (rates) and lead to process instability during anaerobic digestion. To be able to compare results of the different studies reported, and to ensure nutrient limitation is not influencing observations ascribed to process dynamics and/or reaction kinetics, a standard protocol for creating a defined growth medium for anaerobic digestion and mixed culture fermentation is proposed. This paper explains the role(s) of the different macro- and micronutrients, as well as the choices for a growth medium formulation strategy. In addition, the differences in nutrient requirements between mesophilic and thermophilic systems are discussed as well as the importance of specific trace metals regarding specific conversion routes and the possible supplementary requirement of vitamins. The paper will also give some insight into the bio-availability and toxicity of trace metals. A remarkable finding is that mesophilic and thermophilic enzymes are quite comparable at their optimum temperatures. This has consequences for the trace metal requirements of thermophiles under certain conditions. Under non-limiting conditions, the trace metal requirement of thermophilic systems is about 3 times higher than for mesophilic systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Genomic Characterization of Dairy Associated Leuconostoc Species and Diversity of Leuconostocs in Undefined Mixed Mesophilic Starter Cultures.

Science.gov (United States)

Frantzen, Cyril A; Kot, Witold; Pedersen, Thomas B; Ardö, Ylva M; Broadbent, Jeff R; Neve, Horst; Hansen, Lars H; Dal Bello, Fabio; Østlie, Hilde M; Kleppen, Hans P; Vogensen, Finn K; Holo, Helge

2017-01-01

Undefined mesophilic mixed (DL-type) starter cultures are composed of predominantly Lactococcus lactis subspecies and 1-10% Leuconostoc spp. The composition of the Leuconostoc population in the starter culture ultimately affects the characteristics and the quality of the final product. The scientific basis for the taxonomy of dairy relevant leuconostocs can be traced back 50 years, and no documentation on the genomic diversity of leuconostocs in starter cultures exists. We present data on the Leuconostoc population in five DL-type starter cultures commonly used by the dairy industry. The analyses were performed using traditional cultivation methods, and further augmented by next-generation DNA sequencing methods. Bacterial counts for starter cultures cultivated on two different media, MRS and MPCA, revealed large differences in the relative abundance of leuconostocs. Most of the leuconostocs in two of the starter cultures were unable to grow on MRS, emphasizing the limitations of culture-based methods and the importance of careful media selection or use of culture independent methods. Pan-genomic analysis of 59 Leuconostoc genomes enabled differentiation into twelve robust lineages. The genomic analyses show that the dairy-associated leuconostocs are highly adapted to their environment, characterized by the acquisition of genotype traits, such as the ability to metabolize citrate. In particular, Leuconostoc mesenteroides subsp. cremoris display telltale signs of a degenerative evolution, likely resulting from a long period of growth in milk in association with lactococci. Great differences in the metabolic potential between Leuconostoc species and subspecies were revealed. Using targeted amplicon sequencing, the composition of the Leuconostoc population in the five commercial starter cultures was shown to be significantly different. Three of the cultures were dominated by Ln. mesenteroides subspecies cremoris. Leuconostoc pseudomesenteroides dominated in two of the

Comparative study of two purified inulinases from thermophile Thielavia Terrestris NRRL 8126 and mesophile Aspergillus Foetidus NRRL 337 grown on Cichorium Intybus l

Directory of Open Access Journals (Sweden)

Eman Mohamed Fawzi

2011-06-01

Full Text Available Thirty fungal species grown on Cichorium intybus L. root extract as a sole carbon source, were screened for the production of exo-inulinase activities. The thermophile Thielavia terrestris NRRL 8126 and mesophile Aspergillus foetidus NRRL 337 gave the highest production levels of inulinases I & II at 50 and 24 ºC respectively. Yeast extract and peptone were the best nitrogen sources for highest production of inulinases I & II at five and seven days of incubation respectively. The two inulinases I & II were purified to homogeneity by gel-filtration and ion-exchange chromatography with 66.0 and 42.0 fold of purification respectively. The optimum temperatures of purified inulinases I & II were 75 and 50 ºC respectively. Inulinase I was more thermostable than the other one. The optimum pH for activity was found to be 4.5 and 5.5 for inulinases I & II respectively. A comparatively lower Michaelis-Menten constant (2.15 mg/ml and higher maximum initial velocity (115 µmol/min/mg of protein for inulinase I on inulin demonstrated the exoinulinase's greater affinity for inulin substrate. These findings are significant for its potential industrial application. The molecular mass of the inulinases I & II were estimated to be 72 & 78 kDa respectively by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

assesment of mesophilic co assesment of mesophilic co-digestion

African Journals Online (AJOL)

eobe

(fossil) and its attendant pollution menace have provided the avenue to consider alternative ... that anaerobic co-digestion of cow dung with lemon grass produced a high quality biogas. .... for wealth creation as they are harnessed as feed ... enhanced methane yield production [15, 16, 17, 18,. 19]. .... The values given by the.

Effect of temperature on removal of antibiotic resistance genes by anaerobic digestion of activated sludge revealed by metagenomic approach.

Science.gov (United States)

Zhang, Tong; Yang, Ying; Pruden, Amy

2015-09-01

As antibiotic resistance continues to spread globally, there is growing interest in the potential to limit the spread of antibiotic resistance genes (ARGs) from wastewater sources. In particular, operational conditions during sludge digestion may serve to discourage selection of resistant bacteria, reduce horizontal transfer of ARGs, and aid in hydrolysis of DNA. This study applied metagenomic analysis to examine the removal efficiency of ARGs through thermophilic and mesophilic anaerobic digestion using bench-scale reactors. Although the relative abundance of various ARGs shifted from influent to effluent sludge, there was no measureable change in the abundance of total ARGs or their diversity in either the thermophilic or mesophilic treatment. Among the 35 major ARG subtypes detected in feed sludge, substantial reductions (removal efficiency >90%) of 8 and 13 ARGs were achieved by thermophilic and mesophilic digestion, respectively. However, resistance genes of aadA, macB, and sul1 were enriched during the thermophilic anaerobic digestion, while resistance genes of erythromycin esterase type I, sul1, and tetM were enriched during the mesophilic anaerobic digestion. Efflux pump remained to be the major antibiotic resistance mechanism in sludge samples, but the portion of ARGs encoding resistance via target modification increased in the anaerobically digested sludge relative to the feed. Metagenomic analysis provided insight into the potential for anaerobic digestion to mitigate a broad array of ARGs.

A fuzzy-logic-based model to predict biogas and methane production rates in a pilot-scale mesophilic UASB reactor treating molasses wastewater

International Nuclear Information System (INIS)

Turkdogan-Aydinol, F. Ilter; Yetilmezsoy, Kaan

2010-01-01

A MIMO (multiple inputs and multiple outputs) fuzzy-logic-based model was developed to predict biogas and methane production rates in a pilot-scale 90-L mesophilic up-flow anaerobic sludge blanket (UASB) reactor treating molasses wastewater. Five input variables such as volumetric organic loading rate (OLR), volumetric total chemical oxygen demand (TCOD) removal rate (R V ), influent alkalinity, influent pH and effluent pH were fuzzified by the use of an artificial intelligence-based approach. Trapezoidal membership functions with eight levels were conducted for the fuzzy subsets, and a Mamdani-type fuzzy inference system was used to implement a total of 134 rules in the IF-THEN format. The product (prod) and the centre of gravity (COG, centroid) methods were employed as the inference operator and defuzzification methods, respectively. Fuzzy-logic predicted results were compared with the outputs of two exponential non-linear regression models derived in this study. The UASB reactor showed a remarkable performance on the treatment of molasses wastewater, with an average TCOD removal efficiency of 93 (±3)% and an average volumetric TCOD removal rate of 6.87 (±3.93) kg TCOD removed /m 3 -day, respectively. Findings of this study clearly indicated that, compared to non-linear regression models, the proposed MIMO fuzzy-logic-based model produced smaller deviations and exhibited a superior predictive performance on forecasting of both biogas and methane production rates with satisfactory determination coefficients over 0.98.

A fuzzy-logic-based model to predict biogas and methane production rates in a pilot-scale mesophilic UASB reactor treating molasses wastewater

Energy Technology Data Exchange (ETDEWEB)

Turkdogan-Aydinol, F. Ilter, E-mail: aydin@yildiz.edu.tr [Yildiz Technical University, Faculty of Civil Engineering, Department of Environmental Engineering, 34220 Davutpasa, Esenler, Istanbul (Turkey); Yetilmezsoy, Kaan, E-mail: yetilmez@yildiz.edu.tr [Yildiz Technical University, Faculty of Civil Engineering, Department of Environmental Engineering, 34220 Davutpasa, Esenler, Istanbul (Turkey)

2010-10-15

A MIMO (multiple inputs and multiple outputs) fuzzy-logic-based model was developed to predict biogas and methane production rates in a pilot-scale 90-L mesophilic up-flow anaerobic sludge blanket (UASB) reactor treating molasses wastewater. Five input variables such as volumetric organic loading rate (OLR), volumetric total chemical oxygen demand (TCOD) removal rate (R{sub V}), influent alkalinity, influent pH and effluent pH were fuzzified by the use of an artificial intelligence-based approach. Trapezoidal membership functions with eight levels were conducted for the fuzzy subsets, and a Mamdani-type fuzzy inference system was used to implement a total of 134 rules in the IF-THEN format. The product (prod) and the centre of gravity (COG, centroid) methods were employed as the inference operator and defuzzification methods, respectively. Fuzzy-logic predicted results were compared with the outputs of two exponential non-linear regression models derived in this study. The UASB reactor showed a remarkable performance on the treatment of molasses wastewater, with an average TCOD removal efficiency of 93 ({+-}3)% and an average volumetric TCOD removal rate of 6.87 ({+-}3.93) kg TCOD{sub removed}/m{sup 3}-day, respectively. Findings of this study clearly indicated that, compared to non-linear regression models, the proposed MIMO fuzzy-logic-based model produced smaller deviations and exhibited a superior predictive performance on forecasting of both biogas and methane production rates with satisfactory determination coefficients over 0.98.

Quantification of the effect of culturing temperature on salt-induced heat resistance of Bacillus species

NARCIS (Netherlands)

Besten, den H.M.W.; Mark, E.J.; Hensen, L.; Abee, T.; Zwietering, M.H.

2010-01-01

Short- and long-term exposure to mild stress conditions can activate stress adaptation mechanisms in pathogens, resulting in a protective effect toward otherwise lethal stresses. The mesophilic strains Bacillus cereus ATCC 14579 and ATCC 10987 and the psychrotolerant strain B. weihenstephanensis

Rational Design of Disulfide Bonds Increases Thermostability of a Mesophilic 1,3-1,4-β-Glucanase from Bacillus terquilensis.

Directory of Open Access Journals (Sweden)

Chengtuo Niu

Full Text Available 1,3-1,4-β-glucanase is an important biocatalyst in brewing industry and animal feed industry, while its low thermostability often reduces its application performance. In this study, the thermostability of a mesophilic β-glucanase from Bacillus terquilensis was enhanced by rational design and engineering of disulfide bonds in the protein structure. Protein spatial configuration was analyzed to pre-exclude the residues pairs which negatively conflicted with the protein structure and ensure the contact of catalytic center. The changes in protein overall and local flexibility among the wild-type enzyme and the designated mutants were predicted to select the potential disulfide bonds for enhancement of thermostability. Two residue pairs (N31C-T187C and P102C-N125C were chosen as engineering targets and both of them were proved to significantly enhance the protein thermostability. After combinational mutagenesis, the double mutant N31C-T187C/P102C-N125C showed a 48.3% increase in half-life value at 60°C and a 4.1°C rise in melting temperature (Tm compared to wild-type enzyme. The catalytic property of N31C-T187C/P102C-N125C mutant was similar to that of wild-type enzyme. Interestingly, the optimal pH of double mutant was shifted from pH6.5 to pH6.0, which could also increase its industrial application. By comparison with mutants with single-Cys substitutions, the introduction of disulfide bonds and the induced new hydrogen bonds were proved to result in both local and overall rigidification and should be responsible for the improved thermostability. Therefore, the introduction of disulfide bonds for thermostability improvement could be rationally and highly-effectively designed by combination with spatial configuration analysis and molecular dynamics simulation.

Study of the operational conditions for anaerobic digestion of urban solid wastes

International Nuclear Information System (INIS)

Castillo M, Edgar Fernando; Cristancho, Diego Edison; Victor Arellano, A.

2006-01-01

This paper describes an experimental evaluation of anaerobic digestion technology as an option for the management of organic solid waste in developing countries. As raw material, a real and heterogeneous organic waste from urban solid wastes was used. In the first experimental phase, seed selection was achieved through an evaluation of three different anaerobic sludges coming from wastewater treatment plants. The methanization potential of these sludges was assessed in three different batch digesters of 500 mL, at two temperature levels. The results showed that by increasing the temperature to 15 deg. C above room temperature, the methane production increases to three times. So, the best results were obtained in the digester fed with a mixed sludge, working at mesophilic conditions (38-40 deg. C). Then, this selected seed was used at the next experimental phase, testing at different digestion times (DT) of 25, 20 and 18 days in a bigger batch digester of 20 L with a reaction volume of 13 L. The conversion rates were registered at the lowest DT (18 days), reaching 44.9 L/kg -1 of wet waste day -1 . Moreover, DT also has a strong influence over COD removal, because there is a direct relationship between solids removal inside the reactor and DT

Microbiological properties of poultry breast meat treated with high-intensity ultrasound.

Science.gov (United States)

Piñon, M I; Alarcon-Rojo, A D; Renteria, A L; Carrillo-Lopez, L M

2018-01-03

Lactic acid, psychrophilic, and mesophilic bacteria, Escherichia coli, Salmonella spp. and Staphylococcus aureus were enumerated on chicken breasts after treatment with different high intensity ultrasound (frequency 40 kHz, intensity 9.6 W/cm -2 ) application times (0, 30, and 50 min) and packaging atmospheres (aerobic and vacuum) after a 7-day storage. The experiment was performed in commercial 7-week-old chicken breasts. Counts were performed prior to and immediately after ultrasonication, and on the 7th day of chill-storage. After sonication and storage, mesophiles, psychrophiles, LAB and S. aureus increased statistically. Psychrophiles decreased significantly under anaerobic packaging. There were no differences among ultrasonication times in terms of mesophiles, psychrophiles, LAB, E. coli and Salmonella spp. S. aureus numbers had a significant reduction after 50 min sonication. Under these experimental conditions, high-intensity ultrasound for 50 min is a control method of S. aureus and the anaerobic packaging reduces numbers of psychrophiles in chicken breast. The effect of ultrasound is only significant after the storage time. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of anaerobic digestion processes for short sludge-age waste activated sludge combined with anammox treatment of digestate liquor.

Science.gov (United States)

Ge, Huoqing; Batstone, Damien; Keller, Jurg

2016-01-01

The need to reduce energy input and enhance energy recovery from wastewater is driving renewed interest in high-rate activated sludge treatment (i.e. short hydraulic and solids retention times (HRT and SRT, respectively)). This process generates short SRT activated sludge stream, which should be highly degradable. However, the evaluation of anaerobic digestion of short SRT sludge has been limited. This paper assesses anaerobic digestion of short SRT sludge digestion derived from meat processing wastewater under thermophilic and mesophilic conditions. The thermophilic digestion system (55°C) achieved 60 and 68% volatile solids destruction at 8 day and 10 day HRT, respectively, compared with 50% in the mesophilic digestion system (35°C, 10 day HRT). The digestion effluents from the thermophilic (8-10 day HRT) and mesophilic systems were stable, as assessed by residual methane potentials. The ammonia rich sludge dewatering liquor was effectively treated by a batch anammox process, which exhibited comparable nitrogen removal rate as the tests using a control synthetic ammonia solution, indicating that the dewatering liquor did not have inhibiting/toxic effects on the anammox activity.

Modelling the number of viable vegetative cells of Bacillus cereus passing through the stomach

NARCIS (Netherlands)

Wijnands, L.M.; Pielaat, A.; Dufrenne, J.B.; Zwietering, M.H.; Leusden, van F.M.

2009-01-01

Aims: Model the number of viable vegetative cells of B. cereus surviving the gastric passage after experiments in simulated gastric conditions. Materials and Methods: The inactivation of stationary and exponential phase vegetative cells of twelve different strains of Bacillus cereus, both mesophilic

Adaptation to environmental temperature is a major determinant of molecular evolutionary rates in archaea.

Science.gov (United States)

Groussin, Mathieu; Gouy, Manolo

2011-09-01

Methods to infer the ancestral conditions of life are commonly based on geological and paleontological analyses. Recently, several studies used genome sequences to gain information about past ecological conditions taking advantage of the property that the G+C and amino acid contents of bacterial and archaeal ribosomal DNA genes and proteins, respectively, are strongly influenced by the environmental temperature. The adaptation to optimal growth temperature (OGT) since the Last Universal Common Ancestor (LUCA) over the universal tree of life was examined, and it was concluded that LUCA was likely to have been a mesophilic organism and that a parallel adaptation to high temperature occurred independently along the two lineages leading to the ancestors of Bacteria on one side and of Archaea and Eukarya on the other side. Here, we focus on Archaea to gain a precise view of the adaptation to OGT over time in this domain. It has been often proposed on the basis of indirect evidence that the last archaeal common ancestor was a hyperthermophilic organism. Moreover, many results showed the influence of environmental temperature on the evolutionary dynamics of archaeal genomes: Thermophilic organisms generally display lower evolutionary rates than mesophiles. However, to our knowledge, no study tried to explain the differences of evolutionary rates for the entire archaeal domain and to investigate the evolution of substitution rates over time. A comprehensive archaeal phylogeny and a non homogeneous model of the molecular evolutionary process allowed us to estimate ancestral base and amino acid compositions and OGTs at each internal node of the archaeal phylogenetic tree. The last archaeal common ancestor is predicted to have been hyperthermophilic and adaptations to cooler environments can be observed for extant mesophilic species. Furthermore, mesophilic species present both long branches and high variation of nucleotide and amino acid compositions since the last archaeal

Ammonia inhibition on hydrogen enriched anaerobic digestion of manure under mesophilic and thermophilic conditions

DEFF Research Database (Denmark)

Wang, Han; Zhang, Yifeng; Angelidaki, Irini

2016-01-01

Capturing of carbon dioxide by hydrogen derived from excess renewable energy (e.g., wind mills) to methane in a microbially catalyzed process offers an attractive technology for biogas production and upgrading. This bioconversion process is catalyzed by hydrogenotrophic methanogens, which are kno...

Species Distribution and Prevalence of Putative Virulence Factors in Mesophilic Aeromonas spp. Isolated from Fresh Retail Sushi

Directory of Open Access Journals (Sweden)

Sunniva Hoel

2017-05-01

Full Text Available Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens because of their widespread occurrence in food, especially seafood and vegetables. The aim of this work was to assess the species identity and phylogenetic relationship of 118 Aeromonas strains isolated from fresh retail sushi from three producers, and to characterize the isolates with respect to genetic and phenotypic virulence factors. We also evaluate the potential hazard associated with their presence in ready-to-eat seafood not subjected to heat treatment. Mesophilic Aeromonas salmonicida was most prevalent (74%, followed by A. bestiarum (9%, A. dhakensis (5%, A. caviae (5%, A. media (4%, A. hydrophila (2%, and A. piscicola (1%. All isolates were considered potentially pathogenic due to the high prevalence of genes encoding hemolysin (hlyA (99%, aerolysin (aerA (98%, cytotoxic enterotoxin (act (86%, heat-labile cytotonic enterotoxin (alt (99%, and heat-stable cytotonic enterotoxin (ast (31%. The shiga-like toxins 1 and 2 (stx-1 and stx-2 were not detected. Moreover, there was heterogeneity in toxin gene distribution among the isolates, and the combination of act/alt/hlyA/aerA was most commonly detected (63%. β-hemolysis was species-dependent and observed in 91% of the isolates. All A. media and A. caviae strains were non-hemolytic. For isolates belonging to this group, lack of hemolysis was possibly related to the absence of the act gene. Swimming motility, linked to adhesion and host invasion, occurred in 65% of the isolates. Partial sequencing of the gyrB gene demonstrated its suitability as a genetic marker for Aeromonas species identification and for assessment of the phylogenetic relationship between the isolates. The gyrB sequence divergence within a given species ranged from 1.3 to 2.9%. A. bestiarum, A. salmonicida, and A. piscicola were the most closely related species; their sequences differed by 2.7–3.4%. The average gyrB sequence

Methane production from marine, green macro-algae

Energy Technology Data Exchange (ETDEWEB)

Hansson, G.

1983-01-01

Fermentation studies have been carried out to produce methane from green algae native to Scandinavian water and suitable for large scale cultivation. Long term semi-continuous fermentations during mesophilic and thermophilic conditions were performed as well as batch fermentations in flasks and syringes. A mixed inoculum was prepared from sediments, rotting seaweed, sewage sludge and rumen contents. Methane production from the seaweed substrate, consisting of ground green algae without any nutrient additions, started immediately in this culture, mesophilicly as well as thermophilicly. Fermentations were carried out with retention times from 27 to 11 days and loading rates from 1.1 to 2.6 g volatile solids (VS added) per litre per day. In the mesophilic fermentation, gas yields were 250-350 ml CH/sub 4//g VS added and the VS-reduction was around 50-55% at all tested retention times and loading rates. The level of volatile fatty acids was very low in this system. In the thermophilic digestor, gas yields were somewhat lower although the VS-reduction was around 50% also in this systems. The VFA-levels were higher and the culture more sensitive to disturbances. Thus no advantages were found with the thermophilic fermentation. In mesophilic batch fermentations the gas production was rather rapid and almost completed after 12-15 days, in agreement with the continuous fermentations. The gas yields in batch experiments were high, 350-480 ml CH/sub 4//g VS added. (Refs. 20).

mesophilic co mesophilic co-digestion of cattle paunch with poultry

African Journals Online (AJOL)

eobe

poultry droppings shows that three digesters had highest cumulative biogas production ... Farm animal wastes contain mostly biodegradable matter and are malodorous, this makes it suitable for anaerobic digestion. Currently there is no organized system of treatment .... 52.8litres respectively, though within a close range.

Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment.

Science.gov (United States)

Olsson, Jesper; Feng, Xin Mei; Ascue, Johnny; Gentili, Francesco G; Shabiimam, M A; Nehrenheim, Emma; Thorin, Eva

2014-11-01

In this study two wet microalgae cultures and one dried microalgae culture were co-digested in different proportions with sewage sludge in mesophilic and thermophilic conditions. The aim was to evaluate if the co-digestion could lead to an increased efficiency of methane production compared to digestion of sewage sludge alone. The results showed that co-digestion with both wet and dried microalgae, in certain proportions, increased the biochemical methane potential (BMP) compared with digestion of sewage sludge alone in mesophilic conditions. The BMP was significantly higher than the calculated BMP in many of the mixtures. This synergetic effect was statistically significant in a mixture containing 63% (w/w VS based) undigested sewage sludge and 37% (w/w VS based) wet algae slurry, which produced 23% more methane than observed with undigested sewage sludge alone. The trend was that thermophilic co-digestion of microalgae and undigested sewage sludge did not give the same synergy. Copyright © 2014 Elsevier Ltd. All rights reserved.

The impact of engineered cobalt, iron, nickel and silver nanoparticles on soil bacterial diversity under field conditions

International Nuclear Information System (INIS)

Shah, Vishal; Collins, Daniel; Shah, Shreya; Walker, Virginia K

2014-01-01

Our understanding of how engineered nanoparticles (NPs) migrate through soil and affect microbial communities is scarce. In the current study we examined how metal NPs, including those from the iron triad (iron, cobalt and nickel), moved through pots of soil maintained under winter field conditions for 50 days, when mesophilic bacteria may not be dividing. Based on total metal analysis, cobalt and nickel were localized in the top layer of soil, even after exposure to high precipitation and freeze–thaw cycles. In contrast, a bimodal distribution of silver was observed. Due to high endogenous levels of iron, the migration pattern of these NPs could not be determined. Pyrosequence analysis of the bacterial communities revealed that there was no significant engineered NP-mediated decline in microbial richness. However, analysis of individual genera showed that Sphingomonas and Lysobacter were represented by fewer sequences in horizons containing elevated metal levels whereas there was an increase in the numbers of Flavobacterium and Niastella. Collectively, the results indicate that along with the differential migration behavior of NPs in the soil matrix, their impact on soil bacterial diversity appears to be dependent on environmental parameters. (paper)

Structural evidence for solvent-stabilisation by aspartic acid as a mechanism for halophilic protein stability in high salt concentrations.

Science.gov (United States)

Lenton, Samuel; Walsh, Danielle L; Rhys, Natasha H; Soper, Alan K; Dougan, Lorna

2016-07-21

Halophilic organisms have adapted to survive in high salt environments, where mesophilic organisms would perish. One of the biggest challenges faced by halophilic proteins is the ability to maintain both the structure and function at molar concentrations of salt. A distinct adaptation of halophilic proteins, compared to mesophilic homologues, is the abundance of aspartic acid on the protein surface. Mutagenesis and crystallographic studies of halophilic proteins suggest an important role for solvent interactions with the surface aspartic acid residues. This interaction, between the regions of the acidic protein surface and the solvent, is thought to maintain a hydration layer around the protein at molar salt concentrations thereby allowing halophilic proteins to retain their functional state. Here we present neutron diffraction data of the monomeric zwitterionic form of aspartic acid solutions at physiological pH in 0.25 M and 2.5 M concentration of potassium chloride, to mimic mesophilic and halophilic-like environmental conditions. We have used isotopic substitution in combination with empirical potential structure refinement to extract atomic-scale information from the data. Our study provides structural insights that support the hypothesis that carboxyl groups on acidic residues bind water more tightly under high salt conditions, in support of the residue-ion interaction model of halophilic protein stabilisation. Furthermore our data show that in the presence of high salt the self-association between the zwitterionic form of aspartic acid molecules is reduced, suggesting a possible mechanism through which protein aggregation is prevented.

Novel Anaerobic Wastewater Treatment System for Energy Generation at Forward Operating Bases

Science.gov (United States)

2016-08-01

quality , methane production , and mem- brane flux. The potential to operate under ambient temperature conditions was also identified as a research topic...AnMBR system decreased organics re- moval, methane production , and effluent quality compared to operation under mesophilic conditions (37 °C). Average...Around the time that we ini- tially shock-loaded the system, our GC became inoperable and thus biogas quality analysis has been outsourced and is still

A new post-treatment system for anaerobic effluents containing a high Ca2+ content

NARCIS (Netherlands)

Vogelaar, J.C.T.; Wal, van der F.; Lettinga, G.

2002-01-01

A novel reactor concept has been developed that combines Ca2 removal and BOD conversion under mesophilic (30 °C ) as well as under thermophilic (55 °C ) conditions. Soluble Ca2 , present in many industrial wastewaters, precipitates as a result of forced aeration in the aerobic bioreactor. The CaCO3

Anaerobic treatment of cassava stillage for hydrogen and methane production in continuously stirred tank reactor (CSTR) under high organic loading rate (OLR)

Energy Technology Data Exchange (ETDEWEB)

Luo, Gang; Xie, Li; Zou, Zhonghai; Wang, Wen; Zhou, Qi [Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), UNEP-Tongji, Tongji University, Siping Road No. 1239, Shanghai 200092 (China); Shim, Hojae [Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau SAR 999078 (China)

2010-11-15

Anaerobic hydrogen and methane production from cassava stillage in continuously stirred tank reactor (CSTR) were investigated in this study. Results showed that the heat-pretreatment of inoculum did not enhance hydrogen yield compared to raw inoculum under mesophilic condition after continuous operation. However, the hydrogen yield increased from about 14 ml H{sub 2}/gVS under mesophilic condition to 69.6 ml H{sub 2}/gVS under thermophilic condition due to the decrease of propionate concentration and inhibition of homoacetogens. Therefore, temperature was demonstrated to be more important than pretreatment of inoculum to enhance the hydrogen production. Under high organic loading rate (OLR) (>10 gVS/(L.d)), the two-phase thermophilic CSTR for hydrogen and methane production was stable with hydrogen and methane yields of 56.6 mlH{sub 2}/gVS and 249 mlCH{sub 4}/gVS. The one-phase thermophilic CSTR for methane production failed due to the accumulation of both acetate and propionate, leading to the pH lower than 6. Instead of propionate alone, the accumulations of both acetate and propionate were found to be related to the breakdown of methane reactor. (author)

Degradation kinetics of di-(2-ethylhexyl) phthalate (DEHP) and organic matter of sewage sludge during composting

International Nuclear Information System (INIS)

Cheng, H.-F.; Kumar, Mathava; Lin, J.-G.

2008-01-01

The potential degradation of di-(2-ethylhexyl) phthalate (DEHP) and organic matter of sewage sludge by composting was investigated using laboratory reactor at different operating conditions (E-1, E-2 and E-3). In all conditions, single stage thermophilic phase was observed within 2 days and almost, 60% of DEHP was degraded under this phase. At the end of composting, total DEHP degradation of more than 85% was observed in all conditions and total carbon reduction was 11.8% in E-1, 7.6% in E-2 and 10.8% in E-3. Similar trend was observed in the degradation of total nitrogen. The reduction of volatile solids (VS) in the composting reactors was 5.4% in E-1 (18 days), 5.5% in E-2 (12 days) and 4.3% in E-3 (18 days). The degradation kinetics of DEHP in thermophilic phase (including initial mesophilic phase) and the phase there after were determined by first order and fractional power kinetics, respectively. The significance of experimental parameters in DEHP degradation was assessed by Pearson correlation approach. Elevated temperature produced during composting was effective for the rapid degradation of DEHP from sewage sludge compared to mesophilic treatment

The fate and effect of monensin during anaerobic digestion of dairy manure under mesophilic conditions

Science.gov (United States)

There is growing concern about environmental impact of residual antibiotics and feed additives in the manure of treated animals. Monensin, a polyether ionophore coccidiostat, is the only feed additive permitted for use in the U.S. for lactating dairy cows. Previous research has shown that up to 5...

The fate and effect of monensin during anaerobic digestion of dairy manure under mesophilic conditions.

Directory of Open Access Journals (Sweden)

Osman A Arikan

Full Text Available There is growing concern about residual antibiotics and feed additives in the manure of treated animals because of the effects of these residues in the environment. Monensin is the most widely used ionophore coccidiostat in the U.S. The objective of this study was to determine the fate and effect of monensin during the anaerobic digestion of dairy manure. Duplicate plug flow field-scale digesters were operated using non-amended dairy manure and dairy manure amended with monensin to 1 and 10 mg/L for 56 days at 30°C at an organic loading rate of 1.4 kg VS/m3-d and 17-day hydraulic retention time. Results showed that monensin was reduced approximately 70% during anaerobic digestion. Methane production from digesters using manure amended with 1 mg/L monensin was comparable to that from digesters operated without added monensin. However, digesters using manure amended with 10 mg/L monensin yielded 75% less methane than digesters using manure without added monensin. These results suggest that anaerobic digestion is an effective treatment for reducing, but not eliminating, monensin in dairy manure. Monensin did not reduce methane production at concentrations expected in dairy manure at recommended dosage rates.

Batch anaerobic co-digestion of Kimchi factory waste silage and swine manure under mesophilic conditions.

Science.gov (United States)

Kafle, Gopi Krishna; Kim, Sang Hun; Sung, Kyung Ill

2012-11-01

The objective of this study was to investigate the feasibility of anaerobic co-digestion of Kimchi factory waste silage (KFWS) with swine manure (SM). Chinese cabbage (CC) is the major waste generated by a Kimchi factory and KFWS was prepared by mixing CC and rice bran (RB) (70:30 on a dry matter basis). In Experiment I, the biogas potential of CC and RB were measured and, in Experiment II, the test was conducted with different ratios of KFWS and SM (KFWS: SM=0:100; 33:67; 67:33; 100:0 by% volatile solids (VS) basis). KFWS produced a 27% higher biogas yield and a 59% higher methane yield compared to CC. The specific biogas yields increased by 19, 40 and 57% with KFWS-33%, KFWS-67% and KFWS-100%, respectively compared to SM-100% (394 mL/g VS). Similarly, VS removal increased by 37, 51 and 74% with KFWS-33%, KFWS-67% and KFWS-100%, respectively compared to SM-100%. These results suggested that Kimchi factory waste could be effectively treated by making silage, and the silage could be used as a potential co-substrate to enhance biogas production from SM digesters. Copyright © 2012 Elsevier Ltd. All rights reserved.

Winery waste recycling through anaerobic co-digestion with waste activated sludge.

Science.gov (United States)

Da Ros, C; Cavinato, C; Pavan, P; Bolzonella, D

2014-11-01

In this study biogas and high quality digestate were recovered from winery waste (wine lees) through anaerobic co-digestion with waste activated sludge both in mesophilic and thermophilic conditions. The two conditions studied showed similar yields (0.40 m(3)/kgCODfed) but different biological process stability: in fact the mesophilic process was clearly more stable than the thermophilic one in terms of bioprocess parameters. The resulting digestates showed good characteristics for both the tested conditions: heavy metals, dioxins (PCDD/F), and dioxin like bi-phenyls (PCBs) were concentred in the effluent if compared with the influent because of the important reduction of the solid dry matter, but remained at levels acceptable for agricultural reuse. Pathogens in digestate decreased. Best reductions were observed in thermophilic condition, while at 37°C the concentration of Escherichia coli was at concentrations level as high as 1000 UFC/g. Dewatering properties of digestates were evaluated by means of the capillary suction time (CST) and specific resistance to filtration (SRF) tests and it was found that a good dewatering level was achievable only when high doses of polymer (more than 25 g per kg dry solids) were added to sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Production of methane by co-digestion of cassava pulp with various concentrations of pig manure

DEFF Research Database (Denmark)

Panichnumsin, Pan; Nopharatana, Annop; Ahring, Birgitte Kiær

2010-01-01

digestion process, the potential of co-digestion of cassava pulp (CP) with pig manure (PM) was further examined. The effect of the co-substrate mixture ratio was carried out in a semi-continuously fed stirred tank reactor (CSTR) operated under mesophilic condition (37 C) and at a constant OLR of 3.5 kg VS m...

High microbial loads found in minimally-processed sliced mushrooms from Italian market.

Science.gov (United States)

Jiang, Haiyang; Miraglia, Dino; Ranucci, David; Donnini, Domizia; Roila, Rossana; Branciari, Raffaella; Li, Cheng

2018-03-31

There is an increased consumer interest in minimally processed vegetables that has led to the development of products, such as pre-cut sliced mushrooms. Few data are available on the hygienic condition and the presence of foodborne pathogens in such products. Therefore, the current study aimed to evaluate the safety and hygienic characteristics of both ready-to-eat and ready-to-cook, pre-cut sliced mushrooms obtained from a local Italian market. For the evaluation of the hygienic condition, the aerobic mesophilic bacteria, aerobic psychrotrophic bacteria and Escherichia coli enumerations were performed. Salmonella spp., Listeria monocytogenes and Campylobacter spp. were considered in the assessment of the foodborne pathogens. High microbial loads were detected, including counts higher than 5 log CFU/g for E. coli and 6 log CFU/g for the other bacteria counts considered, but no pathogens were found. Ready-to-eat and ready-to-cook products differed only for aerobic mesophilic counts (7.87 and 8.26 log CFU/g, respectively, P=0.003). Strategies to enhance the hygienic level of the mushrooms, particularly the ready-to-eat products, are needed.

Biogas recovery in anaerobic digestion plants for pig wastewater

International Nuclear Information System (INIS)

Collivigarelli, C.; Sorlini, S.

2001-01-01

This work deals with a monitoring of thee anaerobic digestion plants in mesophilic conditions treating pig wastewater with the aim to study the treatment efficiency and energetic aspects. A good waste stabilization is reached in all plants, as shown by the high removal efficiency of total and volatile solids and COD, mainly due to the digestion process. On the contrary, Kjeldahl nitrogen and ammonia (low) removal takes place mainly in the final storage tank, thanks to ammonia stripping. The digestion process not only produces a well stabilized wastewater, that can be more surely reused for agricultural spreading, but it offers also an important energy recovery from the biogas combustion, whose specific production varies from 0,78 to 0,99 Nm 3 t - 1 (live weight) d - 1. It is used in cogeneration plants for the combined production of thermal energy (that is reused for waste heating in the digestion tank at mesophilic conditions and for other internal utilizations) and electric energy (that is used for internal requirements while the surplus is sent into the public grid) [it

Changes of physicochemical and microbiologicalparameters of infiltration water at Debina intake in Poznan, unique conditions - a flood

Science.gov (United States)

Kołaska, Sylwia; Jeż-Walkowiak, Joanna; Dymaczewski, Zbysław

2018-02-01

The paper presents characteristics of Debina infiltration intake which provides water for Poznan and neighbouring communes. The evaluation of effectiveness of infiltration process has been done based on the quality parameters of river water and infiltration water. The analysed water quality parameters are as follows: temperature, iron, manganese, DOCKMnO4, TOC, turbidity, colour, dissolved oxygen, free carbon dioxide, conductivity, total hardness, carbonate hardness, pH, heavy metals, detergents and microorganisms. The paper also includes an assessment of the impact of flood conditions on the quality of infiltration water and operation of infiltration intake. In this part of the paper the following parameters were taken into account: iron, manganese, DOCKMnO4, TOC, turbidity, colour, dissolved oxygen, free carbon dioxide, conductivity, total hardness, the total number of microorganisms in 36°C (mesophilic), the total number of microorganisms in 22°C (psychrophilic), coli bacteria, Clostridium perfringens, Escherichia coli, Enterococci. Analysis of the effects of flood on infiltration process leads to the following conclusions: the deterioration of infiltration water quality was due to the deterioration of river water quality, substantial shortening of groundwater passage and partial disappearance of the aeration zone. The observed deterioration of infiltration water quality did not affect the treated water quality, produced at water treatment plant.

Effect of temperature and hydraulic retention time on hydrogen producing granules: Homoacetogenesis and morphological characteristics

International Nuclear Information System (INIS)

Abreu, A. A.; Danko, A. S.; Alves, M. M.

2009-01-01

The effect of temperature and hydraulic retention time (HRT) on the homoacetogenesisi and on the morphological characteristics of hydrogen producing granules was investigated. Hydrogen was produced using an expanded granular sludge blanket (EGSB) reactor, fed with glucose and L-arabinose, under mesophilic (37 degree centigrade), thermophilic (55 degree centigrade), and hyper thermophilic (70 degree centigrade) conditions. (Author)

Influence of two-phase anaerobic digestion on fate of selected antibiotic resistance genes and class I integrons in municipal wastewater sludge

DEFF Research Database (Denmark)

Wu, Ying; Cui, Erping; Zuo, Yiru

2016-01-01

The response of representative antibiotic resistance genes (ARGs) to lab-scale two-phase (acidogenic/methanogenic phase) anaerobic digestion processes under thermophilic and mesophilic conditions was explored. The associated microbial communities and bacterial pathogens were characterized by 16S ...... for ermB and blaTEM. ARGs patterns were correlated with Proteobacteria and Actinobacteria during the two-phase anaerobic digestion....

Influence of high temperature and ethanol on thermostable lignocellulolytic enzymes

DEFF Research Database (Denmark)

Skovgaard, Pernille Anastasia; Jørgensen, Henning

2013-01-01

the influence of temperature and ethanol on enzyme activity and stability in the distillation step, where most enzymes are inactivated due to high temperatures. Two enzyme mixtures, a mesophilic and a thermostable mixture, were exposed to typical process conditions [temperatures from 55 to 65 °C and up to 5...... % ethanol (w/v)] followed by specific enzyme activity analyses and SDS-PAGE. The thermostable and mesophilic mixture remained active at up to 65 and 55 °C, respectively. When the enzyme mixtures reached their maximum temperature limit, ethanol had a remarkable influence on enzyme activity, e.g., the more...... ethanol, the faster the inactivation. The reason could be the hydrophobic interaction of ethanol on the tertiary structure of the enzyme protein. The thermostable mixture was more tolerant to temperature and ethanol and could therefore be a potential candidate for recycling after distillation....

Anaerobic digestion in combination with 2nd generation ethanol production for maximizing biofuels yield from lignocellulosic biomass – testing in an integrated pilot-scale biorefinery plant

DEFF Research Database (Denmark)

Uellendahl, Hinrich; Ahring, Birgitte Kiær

An integrated biorefinery concept for 2nd generation bioethanol production together with biogas production from the fermentation effluent was tested in pilot-scale. The pilot plant comprised pretreatment, enzymatic hydrolysis, hexose and pentose fermentation into ethanol and anaerobic digestion......-VS/(m3•d) a methane yield of 340 L/kg-VS was achieved for thermophilic operation while 270 L/kg-VS was obtained under mesophilic conditions. Thermophilic operation was, however, less robust towards further increase of the loading rate and for loading rates higher than 5 kg-VS/(m3•d) the yield was higher...... for mesophilic than for thermophilic operation. The effluent from the ethanol fermentation showed no signs of toxicity to the anaerobic microorganisms. Implementation of the biogas production from the fermentation effluent accounted for about 30% higher biofuels yield in the biorefinery compared to a system...

Milk contamination in different points of the dairy process. ii mesophilic, psychrotrophic and proteolytic microorganisms/ Contaminação do leite em diferentes pontos da produção leiteira: ii microrganismos mesófilos, psicrotróficos e proteolíticos

Directory of Open Access Journals (Sweden)

Viviane Vieira Gusmão

2004-05-01

Full Text Available Psychrotrophics microorganisms are able to multiply under refrigeration temperatures. They can produce heat-resistant extracellular enzymes that cause organoleptic and structural changes in milk and dairy products. With the objective of determining the frequency of microorganisms in the dairy process, four farms were evaluated in Londrina city – Brazil and different points were assessed. Mesophilic (48hs at 35oC, psychrotrophic (25hs at 21oC and proteolytic (72hs at 22oC microorganisms were researched, and the proteolytic predominant microflora were determined by using the Gram stain technique. The main psychrotrophic contamination points were the residual water on milk cans, on bulk tank and bad cleaned teats, and milk cans and teats were the most important sources of proteolytics. Gram negative bacilli represented 69% of the microorganisms in the refrigerated milk that means 45% of the total proteolytics microorganisms in the dairy process. Gram negative bacilli is most frequent on bad cleaned teats, teatcups, residual water in milk cans and bulk tank. The psychrotroph count in the refrigerated milk was more than the mesophilic count, showing that that psychrotrophics are the best indicatator for refrigerated milk contamination. The psycrotrophics count at all points assessed were greater than the ideal limit (10% of the mesophilic count. Thus as refrigeration at 4oC is not sufficient to control the multiplication of the psycrotrophics group, good practices should be associated to avoid or control milk contamination by psycrotrophics.Os psicrotróficos são microrganismos que têm capacidade de multiplicação em temperaturas de refrigeração. Produzem enzimas termorresistentes como proteases e lipases que promovem alterações organolépticas no leite e comprometem a produção de derivados. Com o objetivo de determinar a freqüência desses microrganismos a produção do leite, foram estudadas 04 propriedades da região de Londrina, PR

Process performance and modelling of anaerobic digestion using source-sorted organic household waste

DEFF Research Database (Denmark)

Khoshnevisan, Benyamin; Tsapekos, Panagiotis; Alvarado-Morales, Merlin

2018-01-01

Three distinctive start-up strategies of biogas reactors fed with source-sorted organic fraction of municipal solid waste were investigated to reveal the most reliable procedure for rapid process stabilization. Moreover, the experimental results were compared with mathematical modeling outputs....... The combination of both experimental and modelling/simulation succeeded in optimizing the start-up process for anaerobic digestion of biopulp under mesophilic conditions....

The effect of sage, sodium erythorbate and a mixture of sage and sodium erythorbate on the quality of turkey meatballs stored under vacuum and modified atmosphere conditions.

Science.gov (United States)

Karpińska-Tymoszczyk, M

2010-12-01

1. The combined effect of sage (S), sodium erythorbate (SE), a mixture of sage and sodium erythorbate (MIX) and vacuum packaging (VP) and modified atmosphere packaging (MAP) on the quality of cooked turkey meatballs stored at 4°C was investigated. The physicochemical properties (colour, MDA, AV, pH, water activity), microbiological quality characteristics (counts of mesophilic and psychrotrophic bacteria, fungi, coliforms and Clostridium sp.) and flavour attributes of meatballs were determined. 2. The values of the colour parameters L*, a* and b* were affected by the additives and packaging method. The colour of meatballs was better protected by sodium erythorbate than by sage or a mixture of sage and sodium erythorbate. The additives effectively stabilised lipids against oxidation and slowed down hydrolytic changes in turkey meatballs. Sage and a mixture of sage and sodium erythorbate showed stronger antioxidant properties than sodium erythorbate added alone. Products with additives were characterised by better sensory quality than control samples. Sage and MIX prevented the growth of mesophilic and psychrotrophic bacteria. All additives inhibited the growth of coliforms. 3. MAP was more effective than VP in maintaining the microbial and sensory quality stability of cooked turkey meatballs. However, VP appears to be a better method as regards the maintaining of lipid stability in turkey meatballs.

Veterinary research, monitoring and advisory services in connection with the establishment and operation of a communal biomass conversion plant. Partial project 2 (VET-BIO-2). Veterinaer forskning, overvaagning og raadgivning i forbindelse med etablering og drift af biogasfaellesanlaeg. Delprojekt 2 (VET-BIO-2); Forsknings- og overvaagningsprogram vedroerende bakterier og parasitter med henblik paa opstilling af et driftsovervaagningsprogram for biogasfaellesanlaeg

Energy Technology Data Exchange (ETDEWEB)

Munch, B.; Bonde Larsen, A.

1990-01-15

From Feb. '88 through June '89, contents of Salmonella, M. paratuberculosis, total coliforms, faecal streptococci, eggs of Ascaris suum, eggs and larvae of Trichostrongylus spp., and oocysts of bovine Eimeria spp. were quantified in 481 samples of raw and treated biomass collected bi-monthly for up to 12 months from five biogas plants. All five were run semi- continuously, two being thermophilic, one mesophilic, and two mesophilic with thermophilic pre-treatment. Herds delivering slurry to each plant ranged rom 6 - 33 cattle and/or pig herds, and daily input of biomass from 40 - 100 tons. Slurry was treated when mixed with other types of biomass, e.g. waste from pig or poultry slaughterhouses, fish industries or oil mills, and separate samples of these biomasses were examined. It is concluded that thermophilic as well as mesophilic digestion with, thermophilic pre-treatment may be capable of reducing numbers of vegetative pathogenic bacteria and intestinal parasites potentially present in incoming material, thus to allow for unrestricted use of the degassed biomass in this respect. This requires a reducing capacity on faecal streptococci of at least 3-4 log{sub 10} units by digestons based on or including a thermophillic treatment, corresponding to a maximal concentration of these bacteria in treated biomass in the order of magnitude of 10{sup 2} per ml. Minimum temperature and biomass retention time in the reactors as registered automatically, together with determinations of faecal streptococci in the end-product, are suggested as suitable monitoring parameters in these cases, to check on compliance with criteria for unrestricted use of treated biomass. For mesophilic biogas plants adequate restrictions on the use of the end-product will depend on individual process technology and local conditions. (author) 24 refs.

Dynamics of antibiotic resistance genes and presence of putative pathogens during ambient temperature anaerobic digestion.

Science.gov (United States)

Resende, J A; Diniz, C G; Silva, V L; Otenio, M H; Bonnafous, A; Arcuri, P B; Godon, J-J

2014-12-01

This study was focused on evaluating the persistency of antimicrobial resistance (AR) genes and putative pathogenic bacteria in an anaerobic digesters operating at mesophilic ambient temperature, in two different year seasons: summer and winter. Abundance and dynamic of AR genes encoding resistance to macrolides (ermB), aminoglycosides (aphA2) and beta-lactams (blaTEM -1 ) and persistency of potentially pathogenic bacteria in pilot-scale anaerobic digesters were investigated. AR genes were determined in the influent and effluent in both conditions. Overall, after 60 days, reduction was observed for all evaluated genes. However, during the summer, anaerobic digestion was more related to the gene reduction as compared to winter. Persistency of potentially pathogenic bacteria was also evaluated by metagenomic analyses compared to an in-house created database. Clostridium, Acinetobacter and Stenotrophomonas were the most identified. Overall, considering the mesophilic ambient temperature during anaerobic digestion (summer and winter), a decrease in pathogenic bacteria detection through metagenomic analysis and AR genes is reported. Although the mesophilic anaerobic digestion has been efficient, the results may suggest medically important bacteria and AR genes persistency during the process. This is the first report to show AR gene dynamics and persistency of potentially pathogenic bacteria through metagenomic approach in cattle manure ambient temperature anaerobic digestion. © 2014 The Society for Applied Microbiology.

Ethylbenzene removal under mesophilic conditions in a multiple-stage biofilter with macadamia nutshells as carrier material

OpenAIRE

Volckaert, Diego; Alvarez Hornos, Francisco Javier; Heynderickx, Philippe; Van Langenhove, Herman

2011-01-01

A biofilter was used to treat air polluted with ethylbenzene. Macadamia nutshells, which are a cheap waste product in Thailand, were chosen as the packing material for the biofilter. The moisture content (6.6 w%), water holding capacity (16.8 w%), nutshell density (1.3 g ml-1) and organic content (78.0 w%) of the macadamia nutshell were measured. The biofilter was operated during 5 months, in which several inlet loads (IL), empty bed residence times (EBRT) and temperatures (T) were applied. A...

A Simple Mathematical Model of the Anaerobic Digestion of Wasted Fruits and Vegetables in Mesophilic Conditions

Directory of Open Access Journals (Sweden)

Elena Chorukova

2015-04-01

Full Text Available Anaerobic digestion is an effective biotechnological process for treatment of different agricultural, municipal and industrial wastes. Use of mathematical models is a powerful tool for investigations and optimisation of the anaerobic digestion. In this paper a simple mathematical model of the anaerobic digestion of wasted fruits and vegetables was developed and verified experimentally and by computer simulations using Simulink. A three-step mass-balance model was considered including the gas phase. The parameter identification was based on a set of 150 days of dynamical experiments in a laboratory bioreactor. Two step identification procedure to estimate 4 model parameters is presented. The results of 15 days of experiment in a pilot-scale bioreactor were then used to validate the model.

High microbial loads found in minimally-processed sliced mushrooms from Italian market

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Haiyang Jiang

2018-04-01

Full Text Available There is an increased consumer interest in minimally processed vegetables that has led to the development of products, such as pre-cut sliced mushrooms. Few data are available on the hygienic condition and the presence of foodborne pathogens in such products. Therefore, the current study aimed to evaluate the safety and hygienic characteristics of both ready-to-eat and ready-to-cook, pre-cut sliced mushrooms obtained from a local Italian market. For the evaluation of the hygienic condition, the aerobic mesophilic bacteria, aerobic psychrotrophic bacteria and Escherichia coli enumerations were performed. Salmonella spp., Listeria monocytogenes and Campylobacter spp. were considered in the assessment of the foodborne pathogens. High microbial loads were detected, including counts higher than 5 log CFU/g for E. coli and 6 log CFU/g for the other bacteria counts considered, but no pathogens were found. Ready-to-eat and ready-to-cook products differed only for aerobic mesophilic counts (7.87 and 8.26 log CFU/g, respectively, P=0.003. Strategies to enhance the hygienic level of the mushrooms, particularly the ready-to-eat products, are needed.

Modeling of uranium bioleaching by Acidithiobacillus ferrooxidans

International Nuclear Information System (INIS)

Rashidi, A.; Safdari, J.; Roosta-Azad, R.; Zokaei-Kadijani, S.

2012-01-01

Highlights: ► A mathematical model for the mesophilic bioleaching of uraninite is introduced. ► New rate expressions are used for the iron precipitation and uranium leaching rates. ► Good fits of the model are obtained, while the values of the parameters are within the range expected. ► The model can be applied to other bioleaching processes under the same conditions. - Abstract: In this paper, a mathematical model for the mesophilic bioleaching of uraninite is developed. The case of constant temperature, pH, and initial ore concentration is considered. The model is validated by comparing the calculated and measured values of uranium extraction, ferric and ferrous iron in solution, and cell concentration. Good fits of the model were obtained, while the values of the parameters were within the range expected. New rate expressions were used for the iron precipitation and uranium leaching rates. The rates of chemical leaching and ferric precipitation are related to the ratio of ferric to ferrous in solution. The fitted parameters can be considered applicable only to this study. In contrast, the model equation is general and can be applied to bioleaching under the same conditions.

Yannick J. Bomble, Ph.D. | NREL

Science.gov (United States)

) Characterization, modeling, and engineering of biomass degrading enzymes from mesophilic and thermophilic bacteria (2016) "Comparing Residue Clusters from Thermophilic and Mesophilic Enzymes Reveals Adaptive Yannick.Bomble@nrel.gov | 303-384-7729 Research Interests Development of thermophilic bacteria for improved

Development of empirical models for performance evaluation of UASB reactors treating poultry manure wastewater under different operational conditions

International Nuclear Information System (INIS)

Yetilmezsoy, Kaan; Sakar, Suleyman

2008-01-01

A nonlinear modeling study was carried out to evaluate the performance of UASB reactors treating poultry manure wastewater under different organic and hydraulic loading conditions. Two identical pilot scale up-flow anaerobic sludge blanket (UASB) reactors (15.7 L) were run at mesophilic conditions (30-35 deg. C) in a temperature-controlled environment with three hydraulic retention times (θ) of 15.7, 12 and 8.0 days. Imposed volumetric organic loading rates (L V ) ranged from 0.65 to 4.257 kg COD/(m 3 day). The pH of the feed varied between 6.68 and 7.82. The hydraulic loading rates (L H ) were controlled between 0.105 and 0.21 m 3 /(m 2 day). The daily biogas production rates ranged between 4.2 and 29.4 L/day. High volumetric COD removal rates (R V ) ranging from 0.546 to 3.779 kg COD removed /(m 3 day) were achieved. On the basis of experimental results, two empirical models having a satisfactory correlation coefficient of about 0.9954 and 0.9416 were developed to predict daily biogas production (Q g ) and effluent COD concentration (S e ), respectively. Findings of this modeling study showed that optimal COD removals ranging from 86.3% to 90.6% were predicted with HRTs of 7.9, 9.5, 11.2, 12.6, 13.7 and 14.3 days, and L V of 1.27, 1.58, 1.78, 1.99, 2.20 and 2.45 kg COD/(m 3 day) for the corresponding influent substrate concentrations (S i ) of 10,000, 15,000, 20,000, 25,000, 30,000 and 35,000 mg/L, respectively

The importance of temperature in the effective sanitization of aqueous effluents: A review of the case for a thermal treatment that is environmentally and economically credible

International Nuclear Information System (INIS)

Burtun, C.

2009-01-01

The survival time of pathogens in the environment is normally longest in cold conditions. A large number of published studies have demonstrated a fall in this period from months or years down to a matter of weeks as the ambient temperature rises into the twenties. The effect of temperature is thus not surprisingly a key actor in the sanitizing efficiency of any biological treatment process as conditions move through the mesophilic range (30 to 45 degree centigrade) towards thermophilic conditions (over 50 degree centigrade) again, many publications report a substantial positive impact of such elevated temperatures on many harmful organisms. (Author)

Avaliação das condições microbiológicas em unidades de alimentação e nutrição Evaluation of microbiological conditions in food service stablishiments

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Nélio José de Andrade

2003-06-01

se encontram, os restaurantes avaliados devem determinar, numa fase inicial, metas a serem atingidas. Em etapas posteriores, deverão atender a recomendações mais exigentes.The microbiological quality of the air in 63 processing areas, in the hands of 68 manipulator personnel, and on 36 equipments and utensils in food service establishments were evaluated. No more than 19% and 32% of the air in processing areas were in good hygienic conditions for mesophilic aerobics, and molds and yeasts, respectively. The number of microorganisms in those areas was below the APHA recommendation, 30 cfu/cm2/per week. As there is no microbiological specification or recommendation for manipulators, in this study, five ranges of microbiological numbers per hand were established (105, in cfu per hand. For mesophilic aerobic bacteria, it was determined the following percentages in the different ranges 12, 21, 35, 19, and 13%, for total coliforms: 54, 27, 13, 6, and 0%, for molds and yeasts: 63, 21, 13, 14, and 0%, and for S. aureus 72, 13, 16, 0, and 0%. Some results showed an inadequate personal hygiene procedure. For mesophilic aerobics, the results showed that 19% of the equipment and utensil surfaces were in good hygienic conditions, according to APHA recommendations (2 cfu/cm2. Using the same recommendations for total coliforms and molds and yeasts, it could be observed that 46 and 45% of the surfaces, respectively, were in good hygienic conditions. It was observed that is necessary to establish standards or specifications more adequate to control microbiological conditions in Brazilian food service establishments. Firstly, these establishments should determine goals for microbiological specification to be reached. After that, they should attend harder specifications.

Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

Science.gov (United States)

Arslan, C.; Sattar, A.; Ji, C.; Sattar, S.; Yousaf, K.; Hashim, S.

2015-11-01

The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste. The maximum cumulative bio-hydrogen production of 650 mL was obtained from noodle waste under thermophilic temperature condition. Most of the production was observed during the first 48 h of incubation, which continued until 72 h of incubation. The decline in pH during this interval was 4.3 and 4.4 from a starting value of 7 under mesophilic and thermophilic conditions, respectively. Most of the glucose consumption was also observed during 72 h of incubation and the maximum consumption was observed during the first 24 h, which was the same duration where the maximum pH drop occurred. The maximum hydrogen yields of 82.47 mL VS-1, 131.38 mL COD-1, and 44.90 mL glucose-1 were obtained from thermophilic food waste, thermophilic noodle waste and mesophilic rice waste, respectively. The production of volatile fatty acids increased with an increase in time and temperature in food waste and noodle waste reactors whereas they decreased with temperature in rice waste reactors. The statistical modelling returned good results with high values of coefficient of determination (R2) for each waste type and 3-D response surface plots developed by using models developed. These plots developed a better understanding regarding the impact of temperature and incubation time on bio-hydrogen production trend, glucose consumption during incubation and volatile fatty acids production.

Hygiene tests in the anaerobic digestion of household refuse

Energy Technology Data Exchange (ETDEWEB)

Maier, H.; Philipp, W.; Wekerle, J.; Strauch, D.

In a pilot plant the disinfecting effect of composting the effluent of an anaerobic mesophilic digestion process of the organic fraction of household refuse was investigated. The dewatered effluent was mixed with straw as bulking material, put in not aerated windrows and aerobically composted. It was further investigated whether the influent of the digester could be disinfected with lime milk prior to the anaerobic mesophilic digestion process. For the evaluation of the disinfection salmonellas, enterococci, klebsiellas, parvo-, polio- and rotavirus were used as test agents. Temperature, total aerobic germ count, enterobacteriaceae and coliforms were also considered. The effect of lime milk in the influent on the digestion process, survival of the test bacteria and gas production was also studied. Both treatments can result in a hygienically safe product. But composting under the conditions given should not be operated during the winter period. Lime treatment of the influent results in a disinfection of the effluent which immediately can be utilized as liquid sludge in agriculture. (orig.)

Comparison of solid-state and submerged-state fermentation for the bioprocessing of switchgrass to ethanol and acetate by Clostridium phytofermentans.

Science.gov (United States)

Jain, Abhiney; Morlok, Charles K; Henson, J Michael

2013-01-01

The conversion of sustainable energy crops using microbiological fermentation to biofuels and bioproducts typically uses submerged-state processes. Alternatively, solid-state fermentation processes have several advantages when compared to the typical submerged-state processes. This study compares the use of solid-state versus submerged-state fermentation using the mesophilic anaerobic bacterium Clostridium phytofermentans in the conversion of switchgrass to the end products of ethanol, acetate, and hydrogen. A shift in the ratio of metabolic products towards more acetate and hydrogen production than ethanol production was observed when C. phytofermentans was grown under solid-state conditions as compared to submerged-state conditions. Results indicated that the end product concentrations (in millimolar) obtained using solid-state fermentation were higher than using submerged-state fermentation. In contrast, the total fermentation products (in weight of product per weight of carbohydrates consumed) and switchgrass conversion were higher for submerged-state fermentation. The conversion of xylan was greater than glucan conversion under both fermentation conditions. An initial pH of 7 and moisture content of 80 % resulted in maximum end products formation. Scanning electron microscopy study showed the presence of biofilm formed by C. phytofermentans growing on switchgrass under submerged-state fermentation whereas bacterial cells attached to surface and no apparent biofilm was observed when grown under solid-state fermentation. To our knowledge, this is the first study reporting consolidated bioprocessing of a lignocellulosic substrate by a mesophilic anaerobic bacterium under solid-state fermentation conditions.

Fermentative hydrogen production from cassava stillage by mixed anaerobic microflora: Effects of temperature and pH

Energy Technology Data Exchange (ETDEWEB)

Luo, Gang; Xie, Li; Zou, Zhonghai; Zhou, Qi [Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), UNEP-Tongji, Tongji University, Siping Road No. 1239, Shanghai 200092 (China); Wang, Jing-Yuan (School of Civil and Environmental Engineering, Nanyang Technological University, N1-01b-45, 50 Nanyang Avenue, 639798 Singapore)

2010-12-15

Fermentative hydrogen production from cassava stillage was conducted to investigate the influences of temperature (37 C, 60 C, 70 C) and initial pH (4-10) in batch experiments. Although the seed sludge was mesophilic anaerobic sludge, maximum hydrogen yield (53.8 ml H{sub 2}/gVS) was obtained under thermophilic condition (60 C), 53.5% and 198% higher than the values under mesophilic (37 C) and extreme-thermophilic (70 C) conditions respectively. The difference was mainly due to the different VFA and ethanol distributions. Higher hydrogen production corresponded with higher ratios of butyrate/acetate and butyrate/propionate. Similar hydrogen yields of 66.3 and 67.8 ml H{sub 2}/gVS were obtained at initial pH 5 and 6 respectively under thermophilic condition. The total amount of VFA and ethanol increased from 3536 to 7899 mg/l with the increase of initial pH from 4 to 10. Initial pH 6 was considered as the optimal pH due to its 19% higher total VFA and ethanol concentration than that of pH 5. Homoacetogenesis and methonogenesis were very dependent on the initial pH and temperature even when the inoculum was heat-pretreated. Moreover, a difference between measured and theoretical hydrogen was observed in this study, which could be attributed to homoacetogenesis, methanogenesis and the degradation of protein. (author)

Relationships between botanical and chemical composition of forages: a multivariate approach to grasslands in the Western Italian Alps.

Science.gov (United States)

Ravetto Enri, Simone; Renna, Manuela; Probo, Massimiliano; Lussiana, Carola; Battaglini, Luca M; Lonati, Michele; Lombardi, Giampiero

2017-03-01

Plant composition of species-rich mountain grasslands can affect the sensorial and chemical attributes of dairy and meat products, with implications for human health. A multivariate approach was used to analyse the complex relationships between vegetation characteristics (botanical composition and plant community variables) and chemical composition (proximate constituents and fatty acid profile) in mesophilic and dry vegetation ecological groups, comprising six different semi-natural grassland types in the Western Italian Alps. Mesophilic and dry grasslands were comparable in terms of phenology, biodiversity indices and proportion of botanical families. The content of total fatty acids and that of the most abundant fatty acids (alpha-linolenic, linoleic and palmitic acids) were mainly associated to nutrient-rich plant species, belonging to the mesophilic grassland ecological group. Mesophilic grasslands showed also higher values of crude protein, lower values of fibre content and they were related to higher pastoral values of vegetation compared to dry grasslands. The proximate composition and fatty acid profile appeared mainly single species dependent rather than botanical family dependent. These findings highlight that forage from mesophilic grasslands can provide higher nutritive value for ruminants and may be associated to ruminant-derived food products with a healthier fatty acid profile. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Mechanism and Effect of Temperature on Variations in Antibiotic Resistance Genes during Anaerobic Digestion of Dairy Manure

Science.gov (United States)

Sun, Wei; Qian, Xun; Gu, Jie; Wang, Xiao-Juan; Duan, Man-Li

2016-07-01

Animal manure comprises an important reservoir for antibiotic resistance genes (ARGs), but the variation in ARGs during anaerobic digestion at various temperatures and its underlying mechanism remain unclear. Thus, we performed anaerobic digestion using dairy manure at three temperature levels (moderate: 20 °C, mesophilic: 35 °C, and thermophilic: 55 °C), to analyze the dynamics of ARGs and bacterial communities by quantitative PCR and 16S rRNA gene sequencing. We found that 8/10 detected ARGs declined and 5/10 decreased more than 1.0 log during thermophilic digestion, whereas only four and five ARGs decreased during moderate and mesophilic digestion, respectively. The changes in ARGs and bacterial communities were similar under the moderate and mesophilic treatments, but distinct from those in the thermophilic system. Potential pathogens such as Bacteroidetes, Proteobacteria, and Corynebacterium were removed by thermophilic digestion but not by moderate and mesophilic digestion. The bacterial community succession was the dominant mechanism that influenced the variation in ARGs and integrons during anaerobic digestion. Thermophilic digestion decreased the amount of mesophilic bacteria (Bacteroidetes and Proteobacteria) carrying ARGs. Anaerobic digestion generally decreased the abundance of integrons by eliminating the aerobic hosts of integrons (Actinomycetales and Bacilli). Thermophilic anaerobic digestion is recommended for the treatment and reuse of animal manure.

Mechanism and Effect of Temperature on Variations in Antibiotic Resistance Genes during Anaerobic Digestion of Dairy Manure.

Science.gov (United States)

Sun, Wei; Qian, Xun; Gu, Jie; Wang, Xiao-Juan; Duan, Man-Li

2016-07-22

Animal manure comprises an important reservoir for antibiotic resistance genes (ARGs), but the variation in ARGs during anaerobic digestion at various temperatures and its underlying mechanism remain unclear. Thus, we performed anaerobic digestion using dairy manure at three temperature levels (moderate: 20 °C, mesophilic: 35 °C, and thermophilic: 55 °C), to analyze the dynamics of ARGs and bacterial communities by quantitative PCR and 16S rRNA gene sequencing. We found that 8/10 detected ARGs declined and 5/10 decreased more than 1.0 log during thermophilic digestion, whereas only four and five ARGs decreased during moderate and mesophilic digestion, respectively. The changes in ARGs and bacterial communities were similar under the moderate and mesophilic treatments, but distinct from those in the thermophilic system. Potential pathogens such as Bacteroidetes, Proteobacteria, and Corynebacterium were removed by thermophilic digestion but not by moderate and mesophilic digestion. The bacterial community succession was the dominant mechanism that influenced the variation in ARGs and integrons during anaerobic digestion. Thermophilic digestion decreased the amount of mesophilic bacteria (Bacteroidetes and Proteobacteria) carrying ARGs. Anaerobic digestion generally decreased the abundance of integrons by eliminating the aerobic hosts of integrons (Actinomycetales and Bacilli). Thermophilic anaerobic digestion is recommended for the treatment and reuse of animal manure.

Effect of Physical and Chemical Operating Parameters on Anaerobic Digestion of Manure and Biogas Production: A Review

Directory of Open Access Journals (Sweden)

Saeed Samani Majd

2017-03-01

Conclusion: High COD removal decrease of VS were achieved in the range of 80-95 % and 65- 92 % respectively in bioreactors. The produced methane was also 48 mmol L-1 to 4681.3 m3 per month for reactors with a volume of 120 ml to 1330 m3 achieved respectively at 37 and 55˚C from the Mesophilic and thermophilic temperatures. Results summarized on the physical and chemical conditions in this paper, can be used to study the effective parameters and optimize conditions used in biogas production.

Metagenomic Analysis of Dairy Bacteriophages: Extraction Method and Pilot Study on Whey Samples Derived from Using Undefined and Defined Mesophilic Starter Cultures.

Science.gov (United States)

Muhammed, Musemma K; Kot, Witold; Neve, Horst; Mahony, Jennifer; Castro-Mejía, Josué L; Krych, Lukasz; Hansen, Lars H; Nielsen, Dennis S; Sørensen, Søren J; Heller, Knut J; van Sinderen, Douwe; Vogensen, Finn K

2017-10-01

Despite being potentially highly useful for characterizing the biodiversity of phages, metagenomic studies are currently not available for dairy bacteriophages, partly due to the lack of a standard procedure for phage extraction. We optimized an extraction method that allows the removal of the bulk protein from whey and milk samples with losses of less than 50% of spiked phages. The protocol was applied to extract phages from whey in order to test the notion that members of Lactococcus lactis 936 (now Sk1virus ), P335, c2 (now C2virus ) and Leuconostoc phage groups are the most frequently encountered in the dairy environment. The relative abundance and diversity of phages in eight and four whey mixtures from dairies using undefined mesophilic mixed-strain cultures containing Lactococcus lactis subsp. lactis biovar diacetylactis and Leuconostoc species (i.e., DL starter cultures) and defined cultures, respectively, were assessed. Results obtained from transmission electron microscopy and high-throughput sequence analyses revealed the dominance of Lc. lactis 936 phages (order Caudovirales , family Siphoviridae ) in dairies using undefined DL starter cultures and Lc. lactis c2 phages (order Caudovirales , family Siphoviridae ) in dairies using defined cultures. The 936 and Leuconostoc phages demonstrated limited diversity. Possible coinduction of temperate P335 prophages and satellite phages in one of the whey mixtures was also observed. IMPORTANCE The method optimized in this study could provide an important basis for understanding the dynamics of the phage community (abundance, development, diversity, evolution, etc.) in dairies with different sizes, locations, and production strategies. It may also enable the discovery of previously unknown phages, which is crucial for the development of rapid molecular biology-based methods for phage burden surveillance systems. The dominance of only a few phage groups in the dairy environment signifies the depth of knowledge

Cross-Comparison of Leaching Strains Isolated from Two Different Regions: Chambishi and Dexing Copper Mines

OpenAIRE

Ngom, Baba; Liang, Yili; Liu, Xueduan

2014-01-01

A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different...

Starter culture development for improving the flavour of Proosdij-type cheese

NARCIS (Netherlands)

Ayad, E.H.E.; Verheul, A.; Bruinenberg, P.; Wouters, J.T.M.; Smit, G.

2003-01-01

The use of the additional mesophilic strain B851, which has specific flavour forming abilities, was tested for improving the flavour development of a Proosdij-type cheese made with a combination of an acidifying mesophilic and an adjunct thermophilic culture. This strain was selected because of its

The impact of enterocin AS-48 on the shelf-life and safety of sardines (Sardina pilchardus) under different storage conditions.

Science.gov (United States)

Ananou, S; Zentar, H; Martínez-Bueno, M; Gálvez, A; Maqueda, M; Valdivia, E

2014-12-01

The purpose of this study was to determine the effect of enterocin AS-48, packaged under normal atmosphere (NA), vacuum (VP) or modified atmosphere (MAP) on the shelf life and safety of fresh sardines (Sardina pilchardus) stored at 5 °C. We studied the effect of these hurdles, alone or combined, on the relevant autochthonous bacterial populations. Total volatile basic nitrogen (TVB-N) content was used as indicative of freshness. Levels of biogenic amines cadaverine, putrescine, tyramine, and histamine were also determined. The application of AS-48 did not reduce the mesophilic, psychrotrophic, or Gram negative bacteria viable cell counts under any of the storage conditions tested. AS-48 did cause significant reductions in viable staphylococci counts, especially under VP. In sardines under NA treated with AS-48, the populations of histamine- and tyramine-forming total and lactic acid bacteria (LAB) showed no significant reductions. MAP or VP with AS-48 allowed reductions (significant at some storage times) in histamine- and tyramine-forming LAB. The TVB-N content was also reduced under normal atmosphere and, especially, in sardines stored under MAP. The most interesting results are those concerning the decrease (by several fold) in the levels of the biogenic amines cadaverine, putrescine, tyramine, and histamine determined after treatment with AS-48. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biodecolorization of the azo dye Reactive Red 2 by a halotolerant enrichment culture.

Science.gov (United States)

Beydilli, M Inan; Pavlostathis, Spyros G

2007-11-01

The decolorization of the azo dye Reactive Red 2 (RR2) under anoxic conditions was investigated using a mesophilic (35 degrees C) halotolerant enrichment culture capable of growth at 100 g/L sodium chloride (NaCl). Batch decolorization assays were conducted with the unacclimated halotolerant culture, and dye decolorization kinetics were determined as a function of the initial dye, biomass, carbon source, and an externally added oxidation-reduction mediator (anthraquinone-2,6-disulphonic acid) concentrations. The maximum biomass-normalized RR2 decolorization rate by the halotolerant enrichment culture under batch, anoxic incubation conditions was 26.8 mg dye/mg VSSxd. Although RR2 decolorization was inhibited at RR2 concentrations equal to and higher than 300 mg/L, the halotolerant culture achieved a 156-fold higher RR2 decolorization rate compared with a previously reported, biomass-normalized RR2 decolorization rate by a mixed mesophilic (35 degrees C) methanogenic culture in the absence of NaCl. Decolorization kinetics at inhibitory RR2 levels were described based on the Haldane model (Haldane, 1965). Five repetitive dyeing/decolorization cycles performed using the halotolerant culture and the same RR2 dyebath solution demonstrated the feasibility of biological renovation and reuse of commercial-strength spent reactive azo dyebaths.

Chemical and ecotoxicological evaluation of biochar produced from residues of biogas production.

Science.gov (United States)

Stefaniuk, Magdalena; Oleszczuk, Patryk; Bartmiński, Piotr

2016-11-15

Analyses were carried out for biochars produced at three temperatures of pyrolysis (400, 600 and 800°C) from solid residue from biogas production (RBP). Separated and non-separated RBP from biogas plants employing different biogas production conditions were pyrolyzed. The contents of heavy metals and polycyclic aromatic hydrocarbons (PAHs) (16 PAH US EPA) were analyzed in biochars. The analyses showed that with an increased pyrolysis temperature, there was an increase in the contents of PAHs and of certain heavy metals (Cr, Cu, Cd, Pb and Mn). In the ecotoxicological tests, it was noted that the effect depended on the temperature of pyrolysis and on the feedstock from which the biochar was produced. The least harmful effect on the test organisms was from biochar produced by separated RBP in a biogas plant operating in mesophilic conditions. The most negative effect on the test organisms was characteristic of biochar produced from non-separated mesophilic RBP. This study shows that the main factors determining the level of toxicity of biochars produced from RBP towards various living organisms are both the method of feedstock production and the temperature at which the process of pyrolysis is conducted. Copyright © 2016 Elsevier B.V. All rights reserved.

Improving Methane Production through Co-Digestion of Canola Straw and Buffalo Dung by H2O2 Pretreatment

Directory of Open Access Journals (Sweden)

ALTAF ALAM NOONARI

2017-01-01

Full Text Available In this study an effect of acidic pre-treatment on the CS (Canola Straw and BD (Buffalo Dung by anaerobic co-digestion was investigated. H2O2 (Hydrogen Peroxide is a mainly accustomed reagent, used as a bleaching agent in the different industries such as paper and wood. In the present study, it was used as a pre-treatment chemical at varying concentrations in batch reactors. The co-digestion of CS and BD was carried out in SAMPTS (Semi-Automatic Methane Potential Test System at mesophilic (37±1oC conditions. The CS was pretreated in glass bottles with different concentrations of the H2O2 for seven days. The inoculum used in the present study was an effluent of the CSTR (Continuous Stirred Tank Reactor, which was treating BD at mesophilic conditions. The specific methane production from the codigestion of canola straw and BD, by the pre-treatment of H2O2 at concentrations of 0.5, 1.0, and 1.5% were 530.8, 544.5, and 510.3 NmL CH4 g/VS, respectively. The significant reduction in the volatile solids of CS was observed at the optimum pre-treatment of 1.0% H2O2.

Improving methane production through co-digestion of canola straw and buffalo dung by H/sub 2/O/sub 2/ pretreatment

International Nuclear Information System (INIS)

Noonari, A.A.; Sahito, A.R.; Brohi, K.M.

2017-01-01

In this study an effect of acidic pre-treatment on the CS (Canola Straw) and BD (Buffalo Dung) by anaerobic co-digestion was investigated. H2O2 (Hydrogen Peroxide) is a mainly accustomed reagent, used as a bleaching agent in the different industries such as paper and wood. In the present study, it was used as a pre-treatment chemical at varying concentrations in batch reactors. The co-digestion of CS and BD was carried out in SAMPTS (Semi-Automatic Methane Potential Test System) at mesophilic (37+-1oC) conditions. The CS was pretreated in glass bottles with different concentrations of the H2O2 for seven days. The inoculum used in the present study was an effluent of the CSTR (Continuous Stirred Tank Reactor), which was treating BD at mesophilic conditions. The specific methane production from the codigestion of canola straw and BD, by the pre-treatment of H2O2 at concentrations of 0.5, 1.0, and 1.5% were 530.8, 544.5, and 510.3 NmL CH4 g/VS, respectively. The significant reduction in the volatile solids of CS was observed at the optimum pre-treatment of 1.0% H2O2. (author)

[Effects of selective methanogenic inhibitors on methanogenesis and methanogenic communities in acetate degrading cultures].

Science.gov (United States)

Ma, Tingting; Cheng, Lei; Liu, Laiyan; Dai, Lirong; Zhou, Zheng; Zhang, Hui

2015-05-04

We evaluated the role of syntrophic acetate oxidation coupled with hydrogenotrophic methanogens in three different methanogenic consortia. Three methanogenic hexadecane degrading consortia named Y15, M82 and SK were taken from the same oily sludge of Shengli oil-field and enriched. They were incubated at 15, 35 and 55 °C, respectively. The consortia amended with acetate and inhibitors of NH4Cl or CH3F were further transferred and incubated at corresponding temperatures. The cultures atlate logarithmic phase were collected for terminal restriction fragment length polymorphism (T-RFLP) combined with cloning and phylogenetic analysis of 16S rRNA gene fragments. Gas chromatograph analysis showed that all of the consortia could grow and produce methane, but the lag phase was delayed and the growth rate was retarded in the cultures amended with inhibitor. Combination analysis of T-RFLP and clone library revealed the predominance of obligate aceticlastic Methanosaeta in the acetate cultures of Y15, M82 and SK. Under the mesophilic and thermophilic conditions, after add inginhibitor the relative abundance of aceticlastic methanogen decreased but hydrogenotrophic methanogen increased. Syntrophic acetate oxidation during methanogenic degradation of petroleum hydrocarbons occurs under mesophilic and thermophilic conditions, although the situation at low temperature seems uncertain.

Development of empirical models for performance evaluation of UASB reactors treating poultry manure wastewater under different operational conditions

Energy Technology Data Exchange (ETDEWEB)

Yetilmezsoy, Kaan [Department of Environmental Engineering, Yildiz Technical University, 34349 Yildiz, Besiktas, Istanbul (Turkey)], E-mail: yetilmez@yildiz.edu.tr; Sakar, Suleyman [Department of Environmental Engineering, Yildiz Technical University, 34349 Yildiz, Besiktas, Istanbul (Turkey)

2008-05-01

A nonlinear modeling study was carried out to evaluate the performance of UASB reactors treating poultry manure wastewater under different organic and hydraulic loading conditions. Two identical pilot scale up-flow anaerobic sludge blanket (UASB) reactors (15.7 L) were run at mesophilic conditions (30-35 deg. C) in a temperature-controlled environment with three hydraulic retention times ({theta}) of 15.7, 12 and 8.0 days. Imposed volumetric organic loading rates (L{sub V}) ranged from 0.65 to 4.257 kg COD/(m{sup 3} day). The pH of the feed varied between 6.68 and 7.82. The hydraulic loading rates (L{sub H}) were controlled between 0.105 and 0.21 m{sup 3}/(m{sup 2} day). The daily biogas production rates ranged between 4.2 and 29.4 L/day. High volumetric COD removal rates (R{sub V}) ranging from 0.546 to 3.779 kg COD{sub removed}/(m{sup 3} day) were achieved. On the basis of experimental results, two empirical models having a satisfactory correlation coefficient of about 0.9954 and 0.9416 were developed to predict daily biogas production (Q{sub g}) and effluent COD concentration (S{sub e}), respectively. Findings of this modeling study showed that optimal COD removals ranging from 86.3% to 90.6% were predicted with HRTs of 7.9, 9.5, 11.2, 12.6, 13.7 and 14.3 days, and L{sub V} of 1.27, 1.58, 1.78, 1.99, 2.20 and 2.45 kg COD/(m{sup 3} day) for the corresponding influent substrate concentrations (S{sub i}) of 10,000, 15,000, 20,000, 25,000, 30,000 and 35,000 mg/L, respectively.

Temperature-driven adaptation of the bacterial community in peat measured by using thymidine and leucine incorporation.

Science.gov (United States)

Ranneklev, S B; Bååth, E

2001-03-01

The temperature-driven adaptation of the bacterial community in peat was studied, by altering temperature to simulate self-heating and a subsequent return to mesophilic conditions. The technique used consisted of extracting the bacterial community from peat using homogenization-centrifugation and measuring the rates of thymidine (TdR) or leucine (Leu) incorporation by the extracted bacterial community at different temperatures. Increasing the peat incubation temperature from 25 degrees C to 35, 45, or 55 degrees C resulted in a selection of bacterial communities whose optimum temperatures for activity correlated to the peat incubation temperatures. Although TdR and Leu incorporations were significantly correlated, the Leu/TdR incorporation ratios were affected by temperature. Higher Leu/TdR incorporation ratios were found at higher temperatures of incubation of the extracted bacterial community. Higher Leu/TdR incorporation ratios were also found for bacteria in peat samples incubated at higher temperatures. The reappearance of the mesophilic community and disappearance of the thermophilic community when the incubation temperature of the peat was shifted down were monitored by measuring TdR incorporation at 55 degrees C (thermophilic activity) and 25 degrees C (mesophilic activity). Shifting the peat incubation temperature from 55 to 25 degrees C resulted in a recovery of the mesophilic activity, with a subsequent disappearance of the thermophilic activity. The availability of substrate for bacterial growth varied over time and among different peat samples. To avoid confounding effects of substrate availability, a temperature adaptation index was calculated. This index consisted of the log(10) ratio of TdR incorporation at 55 and 25 degrees C. The temperature index decreased linearly with time, indicating that no thermophilic activity would be detected by the TdR technique 1 month after the temperature downshift. There were no differences between the slopes of the

Mechanism and Effect of Temperature on Variations in Antibiotic Resistance Genes during Anaerobic Digestion of Dairy Manure

Science.gov (United States)

Sun, Wei; Qian, Xun; Gu, Jie; Wang, Xiao-Juan; Duan, Man-Li

2016-01-01

Animal manure comprises an important reservoir for antibiotic resistance genes (ARGs), but the variation in ARGs during anaerobic digestion at various temperatures and its underlying mechanism remain unclear. Thus, we performed anaerobic digestion using dairy manure at three temperature levels (moderate: 20 °C, mesophilic: 35 °C, and thermophilic: 55 °C), to analyze the dynamics of ARGs and bacterial communities by quantitative PCR and 16S rRNA gene sequencing. We found that 8/10 detected ARGs declined and 5/10 decreased more than 1.0 log during thermophilic digestion, whereas only four and five ARGs decreased during moderate and mesophilic digestion, respectively. The changes in ARGs and bacterial communities were similar under the moderate and mesophilic treatments, but distinct from those in the thermophilic system. Potential pathogens such as Bacteroidetes, Proteobacteria, and Corynebacterium were removed by thermophilic digestion but not by moderate and mesophilic digestion. The bacterial community succession was the dominant mechanism that influenced the variation in ARGs and integrons during anaerobic digestion. Thermophilic digestion decreased the amount of mesophilic bacteria (Bacteroidetes and Proteobacteria) carrying ARGs. Anaerobic digestion generally decreased the abundance of integrons by eliminating the aerobic hosts of integrons (Actinomycetales and Bacilli). Thermophilic anaerobic digestion is recommended for the treatment and reuse of animal manure. PMID:27444518

Anaerobic composting of waste organic fraction. Compostaje anaerobico de la fraccion organica de los residuos

Energy Technology Data Exchange (ETDEWEB)

Baere, L. de; Verdonck, O.; Verstraete, W.

1994-01-01

The dry anaerobic composting can be carried out in mesophilic and thermophilic conditions. Gas production of 6,2 and 8.5 m''3 biogas m''3 daily in laboratory fermenters was obtained. The quality of waste is higher than obtained in aerobic process. The streptococcus sludge was destroyed. This experimental can be applied for big scale and it permits energy recovery and organic compost of municipal solid wastes. (Author)

Temperature-driven adaptation of the bacterial community in peat measured by using thymidine and leucine incorporation

OpenAIRE

Ranneklev, Sissel Brit; Bååth, Erland

2001-01-01

The temperature-driven adaptation of the bacterial community in peat was studied, by altering temperature to simulate self-heating and a subsequent return to mesophilic conditions. The technique used consisted of extracting the bacterial community from peat using homogenization-centrifugation and measuring the rates of thymidine (TdR) or leucine (Leu) incorporation by the extracted bacterial community at different temperatures. Increasing the peat incubation temperature from 25°C to 35, 45, o...

Biomethanation under psychrophilic conditions.

Science.gov (United States)

Dhaked, Ram Kumar; Singh, Padma; Singh, Lokendra

2010-12-01

The biomethanation of organic matter represents a long-standing, well-established technology. Although at mesophilic and thermophilic temperatures the process is well understood, current knowledge on psychrophilic biomethanation is somewhat scarce. Methanogenesis is particularly sensitive to temperature, which not only affects the activity and structure of the microbial community, but also results in a change in the degradation pathway of organic matter. There is evidence of psychrophilic methanogenesis in natural environments, and a number of methanogenic archaea have been isolated with optimum growth temperatures of 15-25 °C. At psychrophilic temperatures, large amounts of heat are needed to operate reactors, thus resulting in a marginal or negative overall energy yield. Biomethanation at ambient temperature can alleviate this requirement, but for stable biogas production, a microbial consortium adapted to low temperatures or a psychrophilic consortium is required. Single-step or two-step high rate anaerobic reactors [expanded granular sludge bed (EGSB) and up flow anaerobic sludge bed (UASB)] have been used for the treatment of low strength wastewater. Simplified versions of these reactors, such as anaerobic sequencing batch reactors (ASBR) and anaerobic migrating blanket reactor (AMBR) have also been developed with the aim of reducing volume and cost. This technology has been further simplified and extended for the disposal of night soil in high altitude, low temperature areas of the Himalayas, where the hilly terrain, non-availability of conventional energy, harsh climate and space constraints limit the application of complicated reactors. Biomethanation at psychrophilic temperatures and the contribution made to night-soil degradation in the Himalayas are reviewed in this article. Copyright © 2010 Elsevier Ltd. All rights reserved.

Quantification of viable but nonculturable Salmonella spp. and Shigella spp. during sludge anaerobic digestion and their reactivation during cake storage.

Science.gov (United States)

Fu, B; Jiang, Q; Liu, H-B; Liu, H

2015-10-01

The presence of viable but nonculturable (VBNC) bacterial pathogens which often fail to be detected by cultivation and can regain the cultivability if the living conditions improve were reported. The objective of this study was to determine the occurrence of VBNC Salmonella spp. and Shigella spp. in the biosolids during anaerobic digestion and its reactivation during the cake storage. The occurrence of VBNC Salmonella spp. and Shigella spp. during mesophilic, temperature-phased, thermophilic anaerobic digestion of sewage sludge and the subsequent storage were studied by RT-qPCR and most probable number (MPN) method. The VBNC incidence of Salmonella spp. and Shigella spp. during thermophilic digestion was four orders of magnitude higher than those of mesophilic digestion. Accordingly, higher resuscitation ratio of VBNC pathogens was also achieved in thermophilic digested sludge. As a result, the culturable Salmonella typhimurium contents in thermophilic digested sludge after cake storage were two orders of magnitude higher than mesophilic digestion. Both quantitative PCR and reverse transcription quantitative PCR assay results showed the two bacterial counting numbers remained stable throughout the cake storage. The results indicate that the increase in the culturable Salmonella spp. and Shigella spp. after centrifugal dewatering was attributed to the resuscitation from the VBNC state to the culturable state. Thermophilic anaerobic digestion mainly induced Salmonella spp. and Shigella spp. into VBNC state rather than killed them, suggesting that the biological safety of sewage sludge by temperature-phased anaerobic digestion should be carefully assessed. © 2015 The Society for Applied Microbiology.

Effects of loading rate and temperature on anaerobic co-digestion of food waste and waste activated sludge in a high frequency feeding system, looking in particular at stability and efficiency.

Science.gov (United States)

Li, Qian; Li, Hao; Wang, Gaojun; Wang, Xiaochang

2017-08-01

A continuously stirred tank reactor (CSTR) with a high feeding frequency (HFF) of once every 15min was employed in order to ease the loading shock frequently occurred in digester with a low feeding frequency. The effects of the organic loading rate (OLR) and temperature on the co-digestion of food waste and waste activated sludge was evaluated in a 302-day long-term experiment. Due to the high hydrolysis rate, the maximum CH 4 yield in a thermophilic reactor was 407mL CH 4 /gVS added , a value that was significantly higher than the 350mL CH 4 /gVS added that occurred in a mesophilic reactor. Although the alkalinity declined when HRT was shorted than 10d, caused by the decrease of conversion ratio from protein to ammonium, the increase of specific methanogenic activity helped HFF system to achieve stable performance at an OLR of 11.2 (HRT 7.5d) and 30.2gVS/L/d (HRT 3d) under mesophilic and thermophilic conditions, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

SPECIFIC FEATURES OF NATIVE CHEMOLITHOTROPHIC MICROBIOTA WASTES PRODUCED BY ENERGY INDUSTRY

Directory of Open Access Journals (Sweden)

I. A. Blayda

2015-10-01

Full Text Available The study's aims were to isolate and establish pure cultures of prevailing microorganisms from the aboriginal consortium in coal fly ash (FAAC, describe their physiology, biochemistry and practically-useful properties, and compare the efficiency of bioleaching metals from fly ash using pure cultures and the consortium. Through enrichment cultures on standard media we isolated pure cultures of the microorganisms which were then preliminarily identified using standard techniques. This allowed us to isolate from FAAC pure cultures of three prevailing strains of mesophilic and moderately thermophilic acidophilic chemolithotrophic bacteriae, belonging to Acidithiobacillus, such as Acidithiobacillus ferrooxidans, and Sulfobacillus. The strains exhibited high oxidative activity in leaching the rare metals Gallium and Germanium, as well as some heavy metals, from fly ash substrate. A comparison of oxidative activity of the isolated strains and the aboriginal consortium under mesophilic conditions led to the conclusion about advantage of consortium, because it had arisen from syntrophy of microbes in the community. This should be taken into account at the developing of bacterial preparations that are optimal for the technogenic substrate.

Development of radicidation process for eradicating Salmonella and Staphylococcus from pork meat products

International Nuclear Information System (INIS)

Alur, M.D.; Kamat, A.S.; Doke, S.N.; Nair, P.M.

1998-01-01

Processed meat products including pork salami, luncheon meat, ham and cocktail sausages maintained at sub-zero temperatures in retail cold storage were found to possess counts of mesophilic aerobes, Staphylococcus and Salmonella counts in the ranges of 10 6 - 10 7 and 10 4 - 10 5 and 10 - 100 cfu/g, respectively. When these processed meat products were subjected to a gamma radiation dose of 2.5 kGy, under cryogenic condition, counts of mesophilic aerobes and Staphylococcus of the samples were reduced by 3-4 log cycles. At the same time, products were completely free from Salmonella. Inoculated pack studies indicated that gamma radiation dose of 4 kGy would suffice to eliminate Salmonella completely even in the case of samples, which were artificially inoculated with a heavy initial inoculum of 10 6 cfu/g. A trained taste panel gave high organoleptic ratings, the radicidized meat products in terms of odour, colour and texture, establishing 4 kGy as an optimum radicidation dose for frozen pork meat products. (author)

Influence of two-phase anaerobic digestion on fate of selected antibiotic resistance genes and class I integrons in municipal wastewater sludge.

Science.gov (United States)

Wu, Ying; Cui, Erping; Zuo, Yiru; Cheng, Weixiao; Rensing, Christopher; Chen, Hong

2016-07-01

The response of representative antibiotic resistance genes (ARGs) to lab-scale two-phase (acidogenic/methanogenic phase) anaerobic digestion processes under thermophilic and mesophilic conditions was explored. The associated microbial communities and bacterial pathogens were characterized by 16S rRNA gene sequencing. A two-phase thermophilic digestion reduced the presence of tetA, tetG, tetX, sul1, ermB, dfrA1, dfrA12 and intI1 exhibiting 0.1-0.72 log unit removal; in contrast, tetO, tetW, sul3, ermF and blaTEM even increased relative to the feed, and sul2 showed no significant decrease. The acidogenic phase of thermophilic digestion was primarily responsible for reducing the quantity of these genes, while the subsequent methanogenic phase caused a rebound in their quantity. In contrast, a two-phase mesophilic digestion process did not result in reducing the quantity of all ARGs and intI1 except for ermB and blaTEM. ARGs patterns were correlated with Proteobacteria and Actinobacteria during the two-phase anaerobic digestion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bio-processing of copper from combined smelter dust and flotation concentrate: a comparative study on the stirred tank and airlift reactors.

Science.gov (United States)

Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

2012-11-30

To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu(2)S, CuS, and Cu(5)FeS(4).Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results. Copyright © 2012 Elsevier B.V. All rights reserved.

Potential for methane production from typical Mediterranean agro-industrial by-products

Energy Technology Data Exchange (ETDEWEB)

Fountoulakis, M.S.; Drakopoulou, S.; Terzakis, S.; Georgaki, E.; Manios, T. [Laboratory of Solid Waste and Wastewater Management, School of Agricultural Technology, Technological Educational Institute of Crete, GR-71004 Iraklio, Crete (Greece)

2008-02-15

This work examines the potential for methane production from anaerobic co-digestion of olive mill wastewater and wine-grape residues with slaughterhouse wastewater. Continuous (mesophilic) and batch (mesophilic and thermophilic) experiments were studied, both with the separate types of by-products and with mixtures. Methane yields from olive oil wastewater, winery residues and slaughterhouse wastewater were 108, 147 and 297 L CH{sub 4} kg{sup -1} COD fed respectively. Co-digestion with 50% olive oil wastewater and 50% slaughterhouse wastewater or 50% winery residues gave a methane yield of 184 and 214 L CH{sub 4} kg{sup -1} COD, respectively. Furthermore, the methane yield was 188 L CH{sub 4} kg{sup -1} COD added, co-digesting a mixture of 50% winery residues and slaughterhouse wastewater. Finally, the same mixtures under thermophilic conditions gave methane yields of 282, 301 and 219 L CH{sub 4} kg{sup -1} COD, respectively. These results suggest that methane can be produced very efficiently by co-digesting olive oil wastewater, wine-grape residues and slaughterhouse wastewater. (author)

Status on Science and Application of Thermophilic Anaerobic Digestion

DEFF Research Database (Denmark)

Ahring, Birgitte Kiær

1994-01-01

Thermophilic anaerobic processes are often regarded as less stable than mesophilic processes. In the paper this postulate is examined and disproved based on real operational data from of full-scale mesophilic and thermophilic biogas plants. The start-up produce for the thermophilic plants was...... for thermophilic digestion along with the implications for the methanogenic bacteria active at these temperatures....

Optimization of expression and properties of the recombinant acetohydroxyacid synthase of Thermotoga maritima

Directory of Open Access Journals (Sweden)

Mohammad S. Eram

2015-12-01

Full Text Available The data provide additional support of the characterization of the biophysical and biochemical properties of the enzyme acetohydroxyacid synthase from the hyperthermophilic bacterium Thermotoga maritima (Eram et al., 2015 [1]. The genes encoding the enzyme subunits have been cloned and expressed in the mesophilic host Escherichia coli. Detailed data include information about the optimization of the expression conditions, biophysical properties of the enzyme and reconstitution of the holoenzyme from individually expressed and purified subunits.

Hydrolytic bacteria in mesophilic and thermophilic degradation of plant biomass

Energy Technology Data Exchange (ETDEWEB)

Zverlov, Vladimir V.; Hiegl, Wolfgang; Koeck, Daniela E.; Koellmeier, Tanja; Schwarz, Wolfgang H. [Department of Microbiology, Technische Universitaet Muenchen, Freising-Weihenstephan (Germany); Kellermann, Josef [Max Planck Institute for Biochemistry, Am Klopferspitz, Martinsried (Germany)

2010-12-15

Adding plant biomass to a biogas reactor, hydrolysis is the first reaction step in the chain of biological events towards methane production. Maize silage was used to enrich efficient hydrolytic bacterial consortia from natural environments under conditions imitating those in a biogas plant. At 55-60 C a more efficient hydrolyzing culture could be isolated than at 37 C. The composition of the optimal thermophilic bacterial consortium was revealed by sequencing clones from a 16S rRNA gene library. A modified PCR-RFLP pre-screening method was used to group the clones. Pure anaerobic cultures were isolated. 70% of the isolates were related to Clostridium thermocellum. A new culture-independent method for identification of cellulolytic enzymes was developed using the isolation of cellulose-binding proteins. MALDI-TOF/TOF analysis and end-sequencing of peptides from prominent protein bands revealed cellulases from the cellulosome of C. thermocellum and from a major cellulase of Clostridium stercorarium. A combined culture of C. thermocellum and C. stercorarium was shown to excellently degrade maize silage. A spore preparation method suitable for inoculation of maize silage and optimal hydrolysis was developed for the thermophilic bacterial consortium. This method allows for concentration and long-term storage of the mixed culture for instance for inoculation of biogas fermenters. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Establishment of thermophilic anaerobic terephthalic acid degradation system through one-step temperature increase startup strategy - Revealed by Illumina Miseq Sequencing.

Science.gov (United States)

Ma, Kai-Li; Li, Xiang-Kun; Wang, Ke; Meng, Ling-Wei; Liu, Gai-Ge; Zhang, Jie

2017-10-01

Over recent years, thermophilic digestion was constantly focused owing to its various advantage over mesophilic digestion. Notably, the startup approach of thermophilic digester needs to be seriously considered as unsuitable startup ways may result in system inefficiency. In this study, one-step temperature increase startup strategy from 37 °C to 55 °C was applied to establish a thermophilic anaerobic system treating terephthalic acid (TA) contained wastewater, meanwhile, the archaeal and bacterial community compositions at steady periods of 37 °C and 55 °C during the experimental process was also compared using Illumina Miseq Sequencing. The process operation demonstrated that the thermophilic TA degradation system was successfully established at 55 °C with over 95% COD reduction. For archaea community, the elevation of operational temperature from 37 °C to 55 °C accordingly increase the enrichment of hydrogenotrophic methanogens but decrease the abundance of the acetotrophic ones. While for bacterial community, the taxonomic analysis suggested that Syntrophorhabdus (27.40%) was the dominant genus promoting the efficient TA degradation under mesophilic condition, whereas OPB95 (24.99%) and TA06 (14.01%) related populations were largely observed and probably take some crucial role in TA degradation under thermophilic condition. Copyright © 2017 Elsevier Ltd. All rights reserved.

Coupling digestion in a pilot-scale UASB reactor and electrochemical oxidation over BDD anode to treat diluted cheese whey.

Science.gov (United States)

Katsoni, Alphathanasia; Mantzavinos, Dionissios; Diamadopoulos, Evan

2014-11-01

The efficiency of the anaerobic treatment of cheese whey (CW) at mesophilic conditions was investigated. In addition, the applicability of electrochemical oxidation as an advanced post-treatment for the complete removal of chemical oxygen demand (COD) from the anaerobically treated cheese whey was evaluated. The diluted cheese whey, having a pH of 6.5 and a total COD of 6 g/L, was first treated in a 600-L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB process, which was operated for 87 days at mesophilic conditions (32 ± 2 °C) at a hydraulic retention time (HRT) of 3 days, led to a COD removal efficiency between 66 and 97 %, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 9 and 18 A and in the presence of NaCl as the supporting electrolyte, complete removal of COD was attained after 3-4 h of reaction. During electrochemical experiments, three groups of organochlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs), and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, alongside free chlorine, are thought to increase the matrix ecotoxicity to Artemia salina.

Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

Energy Technology Data Exchange (ETDEWEB)

Vakylabad, Ali Behrad, E-mail: alibehzad86@yahoo.co.uk [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Engineers of Nano and Bio Advanced Sciences Company (ENBASCo.), ATIC, Mohaghegh University (Iran, Islamic Republic of); Schaffie, Mahin [Department of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ranjbar, Mohammad [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Manafi, Zahra [Sarcheshmeh Copper Complex, National Iranian Copper Industry Company (Iran, Islamic Republic of); Darezereshki, Esmaeel [Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Energy and Environmental Engineering Research Center (EERC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

2012-11-30

Highlights: Black-Right-Pointing-Pointer Flotation concentrate and smelter dust were sampled and combined. Black-Right-Pointing-Pointer Copper bioleaching from the combined was investigated. Black-Right-Pointing-Pointer Two bio-reactors were investigated and optimized: stirred and airlift. Black-Right-Pointing-Pointer STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu{sub 2}S, CuS, and Cu{sub 5}FeS{sub 4}.Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

Corexit 9500 Enhances Oil Biodegradation and Changes ...

Science.gov (United States)

While COREXIT 9500 is widely applied after oil spills for its reported dispersing activity, there is still a debate on the effectiveness on enhancing oil biodegradation and its potential toxic effect on microbial communities. To better understand the impact of COREXIT 9500 on the structure and activity levels of hydrocarbon degrading microbial communities, we analyzed next-generation 16S rRNA gene sequencing libraries of hydrocarbon enrichments grown at cryophilic and mesophilic conditions and using both DNA and RNA extracts as sequencing templates. Oil biodegradation patterns in both cryophilic and mesophilic enrichments were consistent with those reported in the literature (i.e., aliphatics were degraded faster than aromatics). A slight increase in biodegradation was observed in the presence of COREXIT at both 25°C and 5°C experiments. Differences in community structure were observed between treatment conditions in the DNA-based libraries. The 25°C consortia was dominated by unclassified members of the Vibrio, Pseudoidiomarina, Marinobacter, Alcanivorax, and Thallassospira species, while the 5°C consortia were dominated by several genera of Flavobacteria, Alcanivorax and Oleispira. With the exception of Vibrio-like species, members of these genera have been linked to hydrocarbon degradation and have been observed after oil spills. Colwellia and Cycloclasticus, known aromatic degraders, was also found in these enrichments. RNA-based sequencing of 25°C

Investigation into the effect of high concentrations of volatile fatty acids in anaerobic digestion on methanogenic communities

Energy Technology Data Exchange (ETDEWEB)

Franke-Whittle, Ingrid H., E-mail: ingrid.whittle@uibk.ac.at [Institut für Mikrobiologie, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck (Austria); Walter, Andreas [Institut für Mikrobiologie, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck (Austria); Ebner, Christian [Abwasserverband Zirl und Umgebung, Meilbrunnen 5, 6170 Zirl (Austria); Insam, Heribert [Institut für Mikrobiologie, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck (Austria)

2014-11-15

Highlights: • Different methanogenic communities in mesophilic and thermophilic reactors. • High VFA levels do not cause major changes in archaeal communities. • Real-time PCR indicated greater diversity than ANAEROCHIP microarray. - Abstract: A study was conducted to determine whether differences in the levels of volatile fatty acids (VFAs) in anaerobic digester plants could result in variations in the indigenous methanogenic communities. Two digesters (one operated under mesophilic conditions, the other under thermophilic conditions) were monitored, and sampled at points where VFA levels were high, as well as when VFA levels were low. Physical and chemical parameters were measured, and the methanogenic diversity was screened using the phylogenetic microarray ANAEROCHIP. In addition, real-time PCR was used to quantify the presence of the different methanogenic genera in the sludge samples. Array results indicated that the archaeal communities in the different reactors were stable, and that changes in the VFA levels of the anaerobic digesters did not greatly alter the dominating methanogenic organisms. In contrast, the two digesters were found to harbour different dominating methanogenic communities, which appeared to remain stable over time. Real-time PCR results were inline with those of microarray analysis indicating only minimal changes in methanogen numbers during periods of high VFAs, however, revealed a greater diversity in methanogens than found with the array.

Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

International Nuclear Information System (INIS)

Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

2012-01-01

Highlights: ► Flotation concentrate and smelter dust were sampled and combined. ► Copper bioleaching from the combined was investigated. ► Two bio-reactors were investigated and optimized: stirred and airlift. ► STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu 2 S, CuS, and Cu 5 FeS 4 .Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

Anaerobic digestion of Chinese cabbage waste silage with swine manure for biogas production: batch and continuous study.

Science.gov (United States)

Kafle, Gopi Krishna; Bhattarai, Sujala; Kim, Sang Hun; Chen, Lide

2014-01-01

The aim of this study was to investigate the potential for anaerobic co-digestion of Chinese cabbage waste silage (CCWS) with swine manure (SM). Batch and continuous experiments were carried out under mesophilic anaerobic conditions (36-38°C). The batch test evaluated the effect of CCWS co-digestion with SM (SM: CCWS=100:0; 25:75; 33:67; 0:100, % volatile solids (VS) basis). The continuous test evaluated the performance of a single stage completely stirred tank reactor with SM alone and with a mixture of SM and CCWS. Batch test results showed no significant difference in biogas yield up to 25-33% of CCWS; however, biogas yield was significantly decreased when CCWS contents in feed increased to 67% and 100%. When testing continuous digestion, the biogas yield at organic loading rate (OLR) of 2.0 g VSL⁻¹ d⁻¹ increased by 17% with a mixture of SM and CCWS (SM:CCWS=75:25) (423 mL g⁻¹ VS) than with SM alone (361 mL g⁻¹ VS). The continuous anaerobic digestion process (biogas production, pH, total volatile fatty acids (TVFA) and TVFA/total alkalinity ratios) was stable when co-digesting SM and CCWS (75:25) at OLR of 2.0 g VSL⁻¹ d⁻¹ and hydraulic retention time of 20 days under mesophilic conditions.

[Microbiological and physicochemical evaluation of pasteurized nectar elaborated with tree tomato (Cyphomandra betaceae Sendth)pulp].

Science.gov (United States)

Moreno Alvarez, Mario José; Girán, Nathaly; Serrano, Karla; García, David; Belén Camacho, Douglas R

2003-09-01

Tree tomato (Cyphomandra betaceae Sendth) is a species from high tropical regions. In Venezuela, it is cultivate at the Andean and Aragua state but its consumption is restricted as fruit-fresh, though it a nutritious and industrial potential due its provitamin A content. In this research four nectars were elaborated in proportion I L pulp/4 L of water (1:4) and addition of ascorbic acid (I: 0%; II: 0.5%; III: 1.0 y IV: 1.5%). The nectars were pasteurized (60 degrees C for 30 min), tuned into amber bottle, and stored under refrigeration conditions (7.0 +/- 1.0 degrees C). Weekly during 21 days the mesophilic bacteria, molds, yeasts, total coliforms (MPN/mL), pH, degree Brix, acidity, total carotenoids, vitamin C and total sugars were evaluated. The mesophilic bacteria content was 0.05) were founded on: pH. degree Brix and total sugars. Significant differences (P < 0.05) were founded in vitamin C and total carotenoids content. Sensorial analysis did not show significant differences between formulations for the smell and flavor attributes, when the color was discriminate during the evaluations. The formulation I (without acid ascorbic) had more preference due its color. In conclusion, the nectars showed useful life of 14-21 days under refrigeration condition storage due to the adequate physicochemical and microbiological quality of the product.

Physiology of thermophilic bacteria

Energy Technology Data Exchange (ETDEWEB)

Ljungdahl, L G

1979-01-01

Thermophilic micro-organisms have all of the properties normally found in mesophilic micro-organisms. These include metabolic pathways, regulatory mechanisms such as allosteric or feedback control, repression and induction of protein synthesis, growth yields and metabolic rates. The main difference between thermophiles and mesophiles is the former's capacity to grow at high temperatures. The basis for this capacity is the thermophile's capability to synthesize proteins, complex structures and membranes that are stable or are stabilized and functional at thermophilic temperatures. It is proposed that the maximum and minimum growth temperatures are normally determined by properties associated with proteins, and that the membrane plays a lesser role in determining these temperatures. Enzymes and other proteins from thermophiles, except for having higher thermostability, are very similar to corresponding proteins from mesophiles. The higher thermostability is generally dependent on subtle changes in the composition and sequence of the amino acids and rarely dependent on non-proteinaceous factors. Although over 100 proteins have been purified from thermophiles and compared with corresponding proteins from mesophiles, the exact nature of the higher thermostability has yet to be determined in a protein from a thermophile.

MICROBIOLOGICAL ASPECTS OF ESCHERICHIA COLI IN URINARY TRACT INFECTIONS IN SOWS OF COMMERCIAL FARMS IN SINOP-MT

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L. F. B. Venancio

2017-12-01

Full Text Available Urinary infections (UI in nuts are highly prevalent in modern intensive farming systems and cause significant economic losses, especially for reproductive failure and shortening the life of the array. The most frequently isolated agent is the bacterium Escherichia coli (E. coli. Variables such as environmental contamination pressure, management, nutrition, physiological and anatomical facilities and conditions of the animal itself are directly linked to illness. The objective of this work was to monitor microbiological urine nuts with suspected UI on commercial farms in the municipality of Sinop-MT, by counting of aerobic mesophilic total of Escherichia coli research and antimicrobial susceptibility profile. Urine samples with aerobic mesophilic total counts above 105UFC / mL were considered positive, confirming IU in 12 samples (28.57% of the 42 females subjected to collections. Of the 42 urine samples, 305 were isolated colonies of Gram negative bacteria and through biochemical tests it was confirmed E.coli in 165 (54.09% of these. In 37 (88.09% of the 42 samples collected had involvement of E. coli, with or without other pathogens and all positive samples for UI by total aerobic mesophilic bacteria count showed. Through the antimicrobial susceptibility profile test, E. coli strains showed sensitivity to the following percentages: Gentamicin (100%, Streptomycin (98.70%, Neomycin (92.85% Doxycycline (91.55% , Enrofloxacin (80.51%, Sulfazotrim (64.28%, Ampicillin (62.97%, tetracycline (61.68% and Amoxicillin (24.04%. The diagnosis of UI should be carried out thoroughly, assessing clinical and microbiological aspects, for the identification of the microorganism involved and the realization of antimicrobial susceptibility testing prevents the appearance of multi-resistant bacterial strains.

Detoxification of biomass derived acetate via metabolic conversion to ethanol, acetone, isopropanol, or ethyl acetate

Science.gov (United States)

Sillers, William Ryan; Van Dijken, Hans; Licht, Steve; Shaw, IV, Arthur J.; Gilbert, Alan Benjamin; Argyros, Aaron; Froehlich, Allan C.; McBride, John E.; Xu, Haowen; Hogsett, David A.; Rajgarhia, Vineet B.

2017-03-28

One aspect of the invention relates to a genetically modified thermophilic or mesophilic microorganism, wherein a first native gene is partially, substantially, or completely deleted, silenced, inactivated, or down-regulated, which first native gene encodes a first native enzyme involved in the metabolic production of an organic acid or a salt thereof, thereby increasing the native ability of said thermophilic or mesophilic microorganism to produce lactate or acetate as a fermentation product. In certain embodiments, the aforementioned microorganism further comprises a first non-native gene, which first non-native gene encodes a first non-native enzyme involved in the metabolic production of lactate or acetate. Another aspect of the invention relates to a process for converting lignocellulosic biomass to lactate or acetate, comprising contacting lignocellulosic biomass with a genetically modified thermophilic or mesophilic microorganism.

Dancing to a Different Tune: Adaptive Evolution Fine-Tunes Protein Dynamics

Science.gov (United States)

2015-09-01

efficiency at low temperatures when the enzymes from mesophilic bacteria were evolved to have stabilities as high as their thermophilic homologs. The work...wild-type enzyme . This unfolding temperature is relatively high for a non- thermophilic enzyme ,15 as mesophilic enzymes typically unfold below 60 °C...The work described in this thesis provides a case study exploring the molecular changes underlying adaptive evolution in a key allosteric enzyme . It

Preliminary study of acrylamide monomer decomposition during methane fermentation of dairy waste sludge.

Science.gov (United States)

Mroczek, Ewelina; Konieczny, Piotr; Lewicki, Andrzej; Waśkiewicz, Agnieszka; Dach, Jacek

2016-07-01

Polyacrylamide (PAM) used in sludge dewatering exists widely in high-solid anaerobic digestion. Acrylamide is registered in the list of chemicals demonstrating toxic, carcinogenic and mutagenic properties. Therefore, it is reasonable to ask about the mobility of such residual substances in the environment. The study was carried out to assess the impact of the mesophilic (39±1°C) and thermophilic (54±1°C) fermentation process on the level of acrylamide monomer (AMD) content in the dairy sludge. The material was analysed using high-performance liquid chromatography (HPLC) for quantification of AMD. The results indicate that the process of methane fermentation continues regardless of the temperature effects on the degradation of AMD in dairy sludge. The degree of reduction of acrylamide monomer for thermophilic fermentation is 100%, while for mesophilic fermentation it is 91%. In practice, this means that biogas technology eliminates the risk of AMD migration to plant tissue. Moreover, it should be stressed that 90% of cumulative biogas and methane production was reached one week earlier under thermophilic conditions - the dynamics of the methanisation process were over 20% faster. Copyright © 2016. Published by Elsevier B.V.

EVALUATION OF THE MICROBIAL CONTAMINATION OF HOSPITAL-MADE ENTERAL FEEDINGS

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KATHIA ROSSI ROLIM LOPES

2009-07-01

Full Text Available

ABSTRACT: The quality of enteral feeding formulations prepared at hospital, which are intended for feeding children with malnutrition and diarrhoea, was investigated. A total of eight freshly prepared samples and ten frozen samples were analised. Five of the frozen samples were thawed in the hospital, and the other five in the laboratory, in similar conditions, i. e. in water bath at 50ºC. The freshly prepared samples showed mesophilic aerobic bacteria count varying between 10 to 104 CFU/ml. The presence of total coliform (three samples, fecal coliform (two samples and B. cereus (one sample was also detected. The samples thawed in the laboratory showed a satisfactory quality whilst the formulations thawed in hospital showed higher mesophiles counts and improper counts of S. aureus (two samples and B. cereus (one sample. These results were probably due to a erroneous manipulation of some untrained personnel and emphasize the importance to keep a permanent quality control to avoid the occurrence of contamination, specially for feeding formulations intended for populations at high risk. KEYWORDS: Enteral feeding; bacterial contamination; control.

Structural basis for the aminoacid composition of proteins from halophilic archea.

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Xavier Tadeo

2009-12-01

Full Text Available Proteins from halophilic organisms, which live in extreme saline conditions, have evolved to remain folded at very high ionic strengths. The surfaces of halophilic proteins show a biased amino acid composition with a high prevalence of aspartic and glutamic acids, a low frequency of lysine, and a high occurrence of amino acids with a low hydrophobic character. Using extensive mutational studies on the protein surfaces, we show that it is possible to decrease the salt dependence of a typical halophilic protein to the level of a mesophilic form and engineer a protein from a mesophilic organism into an obligate halophilic form. NMR studies demonstrate complete preservation of the three-dimensional structure of extreme mutants and confirm that salt dependency is conferred exclusively by surface residues. In spite of the statistically established fact that most halophilic proteins are strongly acidic, analysis of a very large number of mutants showed that the effect of salt on protein stability is largely independent of the total protein charge. Conversely, we quantitatively demonstrate that halophilicity is directly related to a decrease in the accessible surface area.

A rigidifying salt-bridge favors the activity of thermophilic enzyme at high temperatures at the expense of low-temperature activity.

Science.gov (United States)

Lam, Sonia Y; Yeung, Rachel C Y; Yu, Tsz-Ha; Sze, Kong-Hung; Wong, Kam-Bo

2011-03-01

Thermophilic enzymes are often less active than their mesophilic homologues at low temperatures. One hypothesis to explain this observation is that the extra stabilizing interactions increase the rigidity of thermophilic enzymes and hence reduce their activity. Here we employed a thermophilic acylphosphatase from Pyrococcus horikoshii and its homologous mesophilic acylphosphatase from human as a model to study how local rigidity of an active-site residue affects the enzymatic activity. Acylphosphatases have a unique structural feature that its conserved active-site arginine residue forms a salt-bridge with the C-terminal carboxyl group only in thermophilic acylphosphatases, but not in mesophilic acylphosphatases. We perturbed the local rigidity of this active-site residue by removing the salt-bridge in the thermophilic acylphosphatase and by introducing the salt-bridge in the mesophilic homologue. The mutagenesis design was confirmed by x-ray crystallography. Removing the salt-bridge in the thermophilic enzyme lowered the activation energy that decreased the activation enthalpy and entropy. Conversely, the introduction of the salt-bridge to the mesophilic homologue increased the activation energy and resulted in increases in both activation enthalpy and entropy. Revealed by molecular dynamics simulations, the unrestrained arginine residue can populate more rotamer conformations, and the loss of this conformational freedom upon the formation of transition state justified the observed reduction in activation entropy. Our results support the conclusion that restricting the active-site flexibility entropically favors the enzymatic activity at high temperatures. However, the accompanying enthalpy-entropy compensation leads to a stronger temperature-dependency of the enzymatic activity, which explains the less active nature of the thermophilic enzymes at low temperatures.

A rigidifying salt-bridge favors the activity of thermophilic enzyme at high temperatures at the expense of low-temperature activity.

Directory of Open Access Journals (Sweden)

Sonia Y Lam

2011-03-01

Full Text Available Thermophilic enzymes are often less active than their mesophilic homologues at low temperatures. One hypothesis to explain this observation is that the extra stabilizing interactions increase the rigidity of thermophilic enzymes and hence reduce their activity. Here we employed a thermophilic acylphosphatase from Pyrococcus horikoshii and its homologous mesophilic acylphosphatase from human as a model to study how local rigidity of an active-site residue affects the enzymatic activity.Acylphosphatases have a unique structural feature that its conserved active-site arginine residue forms a salt-bridge with the C-terminal carboxyl group only in thermophilic acylphosphatases, but not in mesophilic acylphosphatases. We perturbed the local rigidity of this active-site residue by removing the salt-bridge in the thermophilic acylphosphatase and by introducing the salt-bridge in the mesophilic homologue. The mutagenesis design was confirmed by x-ray crystallography. Removing the salt-bridge in the thermophilic enzyme lowered the activation energy that decreased the activation enthalpy and entropy. Conversely, the introduction of the salt-bridge to the mesophilic homologue increased the activation energy and resulted in increases in both activation enthalpy and entropy. Revealed by molecular dynamics simulations, the unrestrained arginine residue can populate more rotamer conformations, and the loss of this conformational freedom upon the formation of transition state justified the observed reduction in activation entropy.Our results support the conclusion that restricting the active-site flexibility entropically favors the enzymatic activity at high temperatures. However, the accompanying enthalpy-entropy compensation leads to a stronger temperature-dependency of the enzymatic activity, which explains the less active nature of the thermophilic enzymes at low temperatures.

Protein Thermostability Is Owing to Their Preferences to Non-Polar Smaller Volume Amino Acids, Variations in Residual Physico-Chemical Properties and More Salt-Bridges.

Science.gov (United States)

Panja, Anindya Sundar; Bandopadhyay, Bidyut; Maiti, Smarajit

2015-01-01

Protein thermostability is an important field for its evolutionary perspective of mesophilic versus thermophilic relationship and for its industrial/ therapeutic applications. Presently, a total 400 (200 thermophilic and 200 mesophilic homologue) proteins were studied utilizing several software/databases to evaluate their amino acid preferences. Randomly selected 50 homologous proteins with available PDB-structure of each group were explored for the understanding of the protein charges, isoelectric-points, hydrophilicity, hydrophobicity, tyrosine phosphorylation and salt-bridge occurrences. These 100 proteins were further probed to generate Ramachandran plot/data for the gross secondary structure prediction in and comparison between the thermophilic and mesophilic proteins. Present results strongly suggest that nonpolar smaller volume amino acids Ala (χ2 = 238.54, psalt bridges in this study. The average percentage of salt-bridge of thermophiles is found to be higher by 20% than their mesophilic homologue. The GLU-HIS and GLU-LYS salt-bridge dyads are calculated to be significantly higher (psalt-bridges and smaller volume nonpolar residues (Gly, Ala and Val) and lesser occurrence of bulky polar residues in the thermophilic proteins. A more stoichiometric relationship amongst these factors minimized the hindrance due to side chain burial and increased compactness and secondary structural stability in thermophilic proteins.

Progress in food irradiation: Belgium

International Nuclear Information System (INIS)

Hespeels, L.

1982-01-01

The Belgian ''Institut National des Radioelements - National Institut voor Radio-Elementen, I.R.E.'' at Fleurus performed the studies described in this report over the years of 1979-82. Subjected to treatment with gamma radiation were: natural gums, dried vegetables, animal protein, egg products, mush rooms, tea leaves, herb teas and gelatine, and the preservation effect on mesophilic, coli-form bacteria as well as on thermophilic and mesophilic spores of Bacillus was examined. The foodstuffs were further tested for mesophilic Chlostridium spores, pathogenic staphylococci, Salmonellae, moulds and yeasts. A slightly increased radiation tolerance following several treatments, but reduced sensitivity to antibiotics was found. Gamma irradiation has shown to be a good preservation method of industrially manufactures enxymes. On whole someness studied, there was no indication of increased mutagenicity or increase in the number of reversions of Salmonella. (AJ) [de

Biomass for energy from field crops

Energy Technology Data Exchange (ETDEWEB)

Zubr, J.

1988-01-01

On the basis of a field experiment, selected crops were evaluated for feasibility in producing biomass applicable as raw material for fuels. Both the main products and byproducts of the crops were investigated in the laboratory for qualitative characteristics and were subjected to methanogenic fermentation under mesophilic conditions. The biogas energy potential and gross energy potential were determined. Under the climatic conditions of Northern Europe, sugar beet (Beta vulgaris) was found to be a superior energy crop. White cabbage (Brassica oleracea var. Capitata), rhubarb (Rheum rhaponticum) and comfrey (Symphytum asperum) can be considered as potential crops for biomass. The agrotechnical and the economic aspects of the biomass production are being subjected to further investigation.

Optimization of the anaerobic co-digestion of pasteurized slaughterhouse waste, pig slurry and glycerine

OpenAIRE

Rodríguez-Abalde, Ángela; Flotats Ripoll, Xavier; Fernández García, Belén

2016-01-01

The feasibility of co-digestion of blends of two different animal by-products (pig manure and pasteurized slaughterhouse waste) and recovered glycerine was studied in mesophilic conditions. Experiments were performed in a lab-scale CSTR along 490 days, with a hydraulic retention time of 21–33 days and with a step-wise increased organic loading rate, by adding and/or changing the wastes ratio, from 0.8 to 3.2 kgCOD m-3 d-1. The best methane production rate (0.64 Nm3CH4 m-3 d-1) represented an ...

Start-up phase of a two-stage anaerobic co-digestion process: Hydrogen and methane production from food waste and vinasse from ethanol industry

DEFF Research Database (Denmark)

Náthia-Neves, Grazielle; Neves, Thiago de Alencar; Berni, Mauro

2018-01-01

The start-up conditions of mesophilic anaerobic co-digestion of restaurant food waste and vinasse, a waste from sugarcane industry, was investigated for efficient biogas production. A pilot plant, containing two reactors, was designed and used sequentially and semi-continuously for biogas...... production. All effective operational parameters were controlled in both reactors over the course of the study. The results indicated that the organic matters were quickly decreased during the start-up phase in the first reactor, resulting in 52% and 64% reduction in total solids and total volatile solids...

MICROBIOLOGICAL SURVEY OF RETAIL HERBS AND SPICES

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A. Santoro

2009-12-01

Full Text Available In the present study, 80 samples of herbs and spices were analyzed for the presence of Bacillus cereus, Salmonella spp., , Escherichia coli, total and fecal coliforms, Enterobacteriacaee, total mesophilic and psychrophilic aerobic organisms, and fungi. Samples were packaged in polyethylene bags or glass containers.High levels of mesophilic aerobic microorganisms were found in most of the samples. B. cereus was present in 27 samples, Clostrium perfringens was isolated from 3 samples, Salmonella spp. was not detected.

Characterization of acetate-utilizing methanogenic bacteria, depending on varying acetate concentrations, in a biogas plant. Phase 1

International Nuclear Information System (INIS)

Ahring, B.K.

1994-12-01

The present report contains the results of a project concerning behaviour of acetate-utilizing methanogenic bacteria in mesophilic and thermophilic biogas plants, collected in 1992 - 1994 period. Labelled acetates (2-C 14 -CH 3 COOH) have been used to characterize the types of methane bacteria populations in the Danish biogas plants, the optimum acetate concentration for these bacteria and acetate metabolism in mesophilic and thermophilic biogas reactors with low acetate concentrations. 2 publications are included. (EG)

Avaliação microbiológica e físico-química de leites uht produzidos no Estado do Paraná - Brasil

OpenAIRE

Dos Santos Bersot, Luciano; Galvão, Júlia Arantes; Raymundo, Nelson Kodama Lançoni; Barcellos, Vinicius Cunha; Pinto, José Paes de Almeida Nogueira [UNESP; Maziero, Maike Taís

2010-01-01

The present work analyzed 150 UHT whole milk samples from three different brands, commercialized in city of Palotina (Paraná, Brazil), between October of 2004 and February of 2005. Mesophilic aerobic bacteria counting results were compared to the Agriculture Ministry of Brazil official standards (RTIQ) for UHT milk. 36 (24%) of the sample presented higher mesophilic bacteria counting according to the standards. Also, were proceeded physic-chemical analyses of those samples. 7.3% of the acidit...

Avaliação da qualidade microbiológica e nutritiva de carnes exóticas

OpenAIRE

Sfaciotte, Ricardo Antonio Pilegi; Universidade Estadual de Maringá; Vignoto, Vanessa Karla Capoia; Universidade Estadual de Maringá; Cardozo, Rejane Machado; Universidade Estadual de Maringá; Munhoz, Patrícia Marques; Universidade Estadual de Maringá; Pinto, Adriana Aparecida; Universidade Estadual de Maringá; Wosiacki, Sheila Rezler; Universidade Estadual de Maringá; Ferraro, Gisela Cristiane; Universidade Estadual de Maringá; Barbosa, Maria José Baptista; Universidade Estadual de Maringá

2015-01-01

Vacuum-packed and frozen of ostrich (Struthio camelus), alligator (Caiman latirostris) and wild boar (Sus scrofa) meat samples were obtained in an authorized commercial store in Maringá/Paraná. Of each kind meat were analyzed 6 samples, where were studied counts of mesophilic aerobic bacteria, aerobic bacteria psichrophilic, coliforms, Escherichia coli and Staphylococcus spp., and protein and fat analysis. The results of aerobic mesophilic bacteria ranged between <1.0 a 3.6 log CFU/g, bein...

Integrated biogas upgrading and hydrogen utilization in an anaerobic reactor containing enriched hydrogenotrophic methanogenic culture

DEFF Research Database (Denmark)

Luo, Gang; Angelidaki, Irini

2012-01-01

Biogas produced by anaerobic digestion, is mainly used in a gas motor for heat and electricity production. However, after removal of CO2, biogas can be upgraded to natural gas quality, giving more utilization possibilities, such as utilization as autogas, or distant utilization by using...... the existing natural gas grid. The current study presents a new biological method for biogas upgrading in a separate biogas reactor, containing enriched hydrogenotrophic methanogens and fed with biogas and hydrogen. Both mesophilic- and thermophilic anaerobic cultures were enriched to convert CO2 to CH4...... by addition of H2. Enrichment at thermophilic temperature (55°C) resulted in CO2 and H2 bioconversion rate of 320 mL CH4/(gVSS h), which was more than 60% higher than that under mesophilic temperature (37°C). Different dominant species were found at mesophilic- and thermophilic-enriched cultures, as revealed...

Primary productivity, heterotrophy, metabolic indicators of stress and interactions in algal-bacterial mat communities affected by a fluctuating thermal regime

International Nuclear Information System (INIS)

Tison, D.L.

1980-01-01

Thermal habitats in effluent cooling waters from production nuclear reactors at the Savannah River Plant are unlike natural thermal habitats in that reactor operations are periodically halted, exposing the organisms growing in these thermal habitats to ambient temperatures for unpredictable lengths of time. Rates of primary production, glucose heterotrophy, and the composition of algal-bacterial mat communities growing along a thermal gradient from about 50 to 35 0 C during periods of reactor operation were studied. Cyanobacteria were the only photoautotrophs in mat communities above 40 0 C while cyanobacteria and eucaryotic algae comprised the photoautotrophic component of mat communities below 40 0 C. The heterotrophic component of these communities above 40 0 C was made up of stenothermic and eurythermic thermophilic bacteria while both eurythermic thermophiles and mesophilic bacteria were found in communities below 40 0 C. Net CO 2 -fixation rates during thermal conditions dropped after initial exposure to ambient temperatures. After prolonged exposure of the thermal communities to ambient temperatures, adaptation and colonization by mesophilic algae occurred. Rates of glucose utilization under varying degrees of thermal influence suggested that the heterotrophic component may not have been optimally adapted to thermal conditions. During periods of changing thermal conditions, an increase in the percentage extracellular release of photosynthetically fixed 14 CO 2 by cyanobacteria and algae and an increase in the percentage of glucose mineralized (respired) by the heterotrophic component of the mat communities was observed. Results of temperature shift experiments indicated that the short-term response of the photoautotrophic component of these communities to thermal stress was an increase in the percentage of photosynthate released extracellularly

A comparison of structural and evolutionary attributes of Escherichia coli and Thermus thermophilus small ribosomal subunits: signatures of thermal adaptation.

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Saurav Mallik

Full Text Available Here we compare the structural and evolutionary attributes of Thermus thermophilus and Escherichia coli small ribosomal subunits (SSU. Our results indicate that with few exceptions, thermophilic 16S ribosomal RNA (16S rRNA is densely packed compared to that of mesophilic at most of the analogous spatial regions. In addition, we have located species-specific cavity clusters (SSCCs in both species. E. coli SSCCs are numerous and larger compared to T. thermophilus SSCCs, which again indicates densely packed thermophilic 16S rRNA. Thermophilic ribosomal proteins (r-proteins have longer disordered regions than their mesophilic homologs and they experience larger disorder-to-order transitions during SSU-assembly. This is reflected in the predicted higher conformational changes of thermophilic r-proteins compared to their mesophilic homologs during SSU-assembly. This high conformational change of thermophilic r-proteins may help them to associate with the 16S ribosomal RNA with high complementary interfaces, larger interface areas, and denser molecular contacts, compared to those of mesophilic. Thus, thermophilic protein-rRNA interfaces are tightly associated with 16S rRNA than their mesophilic homologs. Densely packed 16S rRNA interior and tight protein-rRNA binding of T. thermophilus (compared to those of E. coli are likely the signatures of its thermal adaptation. We have found a linear correlation between the free energy of protein-RNA interface formation, interface size, and square of conformational changes, which is followed in both prokaryotic and eukaryotic SSU. Disorder is associated with high protein-RNA interface polarity. We have found an evolutionary tendency to maintain high polarity (thereby disorder at protein-rRNA interfaces, than that at rest of the protein structures. However, some proteins exhibit exceptions to this general trend.

Hybrid alkali-hydrodynamic disintegration of waste-activated sludge before two-stage anaerobic digestion process.

Science.gov (United States)

Grübel, Klaudiusz; Suschka, Jan

2015-05-01

The first step of anaerobic digestion, the hydrolysis, is regarded as the rate-limiting step in the degradation of complex organic compounds, such as waste-activated sludge (WAS). The aim of lab-scale experiments was to pre-hydrolyze the sludge by means of low intensive alkaline sludge conditioning before applying hydrodynamic disintegration, as the pre-treatment procedure. Application of both processes as a hybrid disintegration sludge technology resulted in a higher organic matter release (soluble chemical oxygen demand (SCOD)) to the liquid sludge phase compared with the effects of processes conducted separately. The total SCOD after alkalization at 9 pH (pH in the range of 8.96-9.10, SCOD = 600 mg O2/L) and after hydrodynamic (SCOD = 1450 mg O2/L) disintegration equaled to 2050 mg/L. However, due to the synergistic effect, the obtained SCOD value amounted to 2800 mg/L, which constitutes an additional chemical oxygen demand (COD) dissolution of about 35 %. Similarly, the synergistic effect after alkalization at 10 pH was also obtained. The applied hybrid pre-hydrolysis technology resulted in a disintegration degree of 28-35%. The experiments aimed at selection of the most appropriate procedures in terms of optimal sludge digestion results, including high organic matter degradation (removal) and high biogas production. The analyzed soft hybrid technology influenced the effectiveness of mesophilic/thermophilic anaerobic digestion in a positive way and ensured the sludge minimization. The adopted pre-treatment technology (alkalization + hydrodynamic cavitation) resulted in 22-27% higher biogas production and 13-28% higher biogas yield. After two stages of anaerobic digestion (mesophilic conditions (MAD) + thermophilic anaerobic digestion (TAD)), the highest total solids (TS) reduction amounted to 45.6% and was received for the following sample at 7 days MAD + 17 days TAD. About 7% higher TS reduction was noticed compared with the sample after 9

Long-term effect of inoculum pretreatment on fermentative hydrogen production by repeated batch cultivations: homoacetogenesis and methanogenesis as competitors to hydrogen production

DEFF Research Database (Denmark)

Luo, Gang; Karakashev, Dimitar Borisov; Xie, Li

2011-01-01

Long-term effects of inoculum pretreatments(heat, acid, loading-shock) on hydrogen production from glucose under different temperatures (378C, 558C) and initial pH (7 and 5.5) were studied by repeated batch cultivations. Results obtained showed that it was necessary to investigate the long......-term effect of inoculum pretreatment on hydrogen production since pretreatments may just temporarily inhibit the hydrogen consuming processes. After long-term cultivation, pretreated inocula did not enhance hydrogen production compared to untreated inocula under mesophilic conditions (initial pH 7 and pH 5.......5) and thermophilic conditions (initial pH 7). However, pretreatment could inhibit lactate production and lead to higher hydrogen yield under thermophilic conditions at initial pH 5.5. The results further demonstrated that inoculum pretreatment could not permanently inhibit either methanogenesis or homoacetogenesis...

Evaluation of working conditions of workers engaged in tending horses

Directory of Open Access Journals (Sweden)

Bożena Nowakowicz-Dębek

2014-11-01

Full Text Available [b]introduction[/b]. A growing interest in the horse business has resulted in the increased engagement of many people in this area, and the health problems occurring among workers create the need to search for prophylactic measures. [b]objective[/b]. The objective of the study was evaluation of the level of exposure to air pollution in a stable, and estimation of the degree of work load among workers engaged in tending horses. [b]material and methods[/b]. The study was conducted twice, during the winter season, in a stable maintaining race horses, and in a social room. In order to evaluate workers’ exposure, air samples were collected by the aspiration method. After the incubation of material, the total number of bacteria and fungi in the air was determined, as well as the number of aerobic mesophilic and thermophilic bacteria, expressed as the number of colony forming units per cubic meter of air (CFU/m[sup]3[/sup]. The measurement of total dust concentration in the air was also performed, simultaneously with the measurement of microclimatic parameters. The study of work load also covered the measurement of energy expenditure, evaluation of static physical load, and monotony of movements performed. [b]conclusions[/b]. The stable may be considered as a workplace with considerable risk of the occurrence of unfavourable health effects.

Relative contributions of archaea and bacteria to microbial ammonia oxidation differ under different conditions during agricultural waste composting.

Science.gov (United States)

Zeng, Guangming; Zhang, Jiachao; Chen, Yaoning; Yu, Zhen; Yu, Man; Li, Hui; Liu, Zhifeng; Chen, Ming; Lu, Lunhui; Hu, Chunxiao

2011-10-01

The aim of this study was to compare the relative contribution of ammonia-oxidizing archaea (AOA) and bacteria (AOB) to nitrification during agricultural waste composting. The AOA and AOB amoA gene abundance and composition were determined by quantitative PCR and denaturing gradient gel electrophoresis (DGGE), respectively. The results showed that the archaeal amoA gene was abundant throughout the composting process, while the bacterial amoA gene abundance decreased to undetectable level during the thermophilic and cooling stages. DGGE showed more diverse archaeal amoA gene composition when the potential ammonia oxidation (PAO) rate reached peak values. A significant positive relationship was observed between the PAO rate and the archaeal amoA gene abundance (R²=0.554; Parchaea dominated ammonia oxidation during the thermophilic and cooling stages. Bacteria were also related to ammonia oxidation activity (R²=0.503; P=0.03) especially during the mesophilic and maturation stages. Copyright © 2011 Elsevier Ltd. All rights reserved.

Use of natural compounds to improve the microbial stability of Amaranth-based homemade fresh pasta.

Science.gov (United States)

Del Nobile, M A; Di Benedetto, N; Suriano, N; Conte, A; Lamacchia, C; Corbo, M R; Sinigaglia, M

2009-04-01

A study on the use of natural antimicrobial compounds to improve the microbiological stability of refrigerated amaranth-based homemade fresh pasta is presented in this work. In particular, the antimicrobial activity of thymol, lemon extract, chitosan and grapefruit seed extract (GFSE) has been tested against mesophilic and psychrotrophic bacteria, total coliforms, Staphylococcus spp., yeasts and moulds. A sensory analysis on both fresh and cooked pasta was also run. Results suggest that chitosan and GFSE strongly increase the microbial acceptability limit of the investigated spoilage microorganisms, being the former the most effective. Thymol efficiently reduces the growth of mesophilic bacteria, psychrotrophic bacteria and Staphylococcus spp., whereas it does not affect, substantially, the growth cycle of total coliforms. Lemon extract is the less effective in preventing microbial growth. In fact, it is able to delay only total mesophilic and psychrotrophic bacterial evolution. From a sensorial point of view no significant differences were recorded between the control samples and all the types of loaded amaranth-based pasta.

Simulation of Bioleaching Heat Effects for Enhancement of Copper Recovery from Sarcheshmeh Chalcopyrite

Science.gov (United States)

Mahmoudian, Ali Reza; Sadrnezhaad, S. K.; Manafi, Zahra

2014-08-01

A heat-transfer model was formulated to determine the distribution of temperature within a bioheap of chalcopyrite of Sarcheshmeh copper mine. Bioleaching employs mixed mesophilic and thermophilic microbes for Cu extraction. Thermophiles are better than mesophiles to dissolve CuFeS2. The solution irrigation and aeration rates were taken into account as the main operational factors. The model was validated by comparing the temperature profiles of test columns with those of bioheap. The model was used to find the optimal ratio of irrigation to aeration. It was found that when the solution was fed at a flow rate of 5 kg/m2 h and air was blown at a flow rate of 7.5 kg/m2 h, the transition from a mesophilic to thermophilic state inside the heap was possible. In this situation, the maximum temperature rise inside the heap was about 332 K (59 °C) after 60 days.

Thermophilic anaerobic digestion of Lurgi coal gasification wastewater in a UASB reactor

Energy Technology Data Exchange (ETDEWEB)

Wang, W.; Ma, W.C.; Han, H.J.; Li, H.Q.; Yuan, M. [Harbin Institute of Technology, Harbin (China)

2011-02-15

Lurgi coal gasification wastewater (LCGW) is a refractory wastewater, whose anaerobic treatment has been a severe problem due to its toxicity and poor biodegradability. Using a mesophilic (35 {+-} 2{sup o}C) reactor as a control, thermophilic anaerobic digestion (55 {+-} 2{sup o}C) of LCGW was investigated in a UASB reactor. After 120 days of operation, the removal of COD and total phenols by the thermophilic reactor could reach 50-55% and 50-60% respectively, at an organic loading rate of 2.5 kg COD/(m{sup 3} d) and HRT of 24h: the corresponding efficiencies were both only 20-30% in the mesophilic reactor. After thermophilic digestion, the wastewater concentrations of the aerobic effluent COD could reach below 200 mg/L compared with around 294 mg/L if mesophilic digestion was done and around 375 mg/L if sole aerobic pre-treatment was done. The results suggested that thermophilic anaerobic digestion improved significantly both anaerobic and aerobic biodegradation of LCGW.

Short-Term Effect of Vermicompost Application on Biological Properties of an Alkaline Soil with High Lime Content from Mediterranean Region of Turkey

Science.gov (United States)

Uz, Ilker; Tavali, Ismail Emrah

2014-01-01

This study was conducted to investigate direct short-term impact of vermicompost on some soil biological properties by monitoring changes after addition of vermicompost as compared to farmyard manure in an alkaline soil with high lime content from semiarid Mediterranean region of Turkey. For this purpose, mixtures of soil and organic fertilizers in different doses were incubated under greenhouse condition. Soil samples collected in regular intervals were analyzed for biological parameters including dehydrogenase, β-glucosidase, urease, alkaline phosphatase activities, and total number of aerobic mesophilic bacteria. Even though soil dehydrogenase activity appeared to be dose-independent based on overall evaluation, organic amendments were found to elevate dehydrogenase activity when sampling periods are evaluated individually. β-glucosidase, urease, alkaline phosphatase activity, and aerobic mesophilic bacterial numbers in vermicompost treatments fluctuated but remained significantly above the control. A slight but statistically significant difference was detected between organic amendments in terms of urease activity. Vermicompost appeared to more significantly increase bacterial number in soil. Clearly, vermicompost has a potential to be used as an alternative to farmyard manure to improve and maintain soil biological activity in alkaline calcareous soils from the Mediterranean region of Turkey. Further studies are needed to assess its full potential for these soils. PMID:25254238

Using temperature and time criteria to control the effectiveness of continuous thermal sanitation of piggery effluent in terms of set microbial indicators.

Science.gov (United States)

Cunault, C; Pourcher, A M; Burton, C H

2011-12-01

To determine the minimal conditions (temperature-time), necessary to achieve set sanitation targets for selected microbial indicators during the continuous thermal treatment of pig slurry. The effectiveness of thermal treatment between 55 and 96°C was studied using Escherichia coli, enterococci, sulfite-reducing Clostridia (SRC), mesophilic culturable bacteria (MCB), F+-specific and somatic phages. Identification of SRC and MCB was performed using 16S rRNA gene analysis. Ten minutes at 70°C or 1 h at 60°C was sufficient to reduce the vegetative bacteria by 4-5 log(10), but it had little effect on somatic phages nor on spore formers, dominated by Clostridium sp. At 96°C, somatic phages were still detected, but there was a reduction of 3.1 log(10) for SRC and of 1.4 log(10) for MCB. At 96°C, Clostridium botulinum was identified among the thermotolerant MCB. Only those hygienic risks relating to mesophilic vegetative bacteria can be totally eliminated from pig slurry treated at 60°C (60 min) or 70°C (cost treatment using heat recovery). However, even at 96°C, certain pathogens may persist. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology. No claim to French Government works.

Stability of a sweet product of tamarillo (Cyphomandra betacea preserved by combined methods

Directory of Open Access Journals (Sweden)

Villegas-Ruíz Xadeni

2013-06-01

Full Text Available The aim of this study was the use of the hurdle technology for preparing a sweet product (SPT of tamarillo (Cyphomandra betacea and assess its storage stability. SPT was prepared at the fruit natural pH (3.72, lowering the water activity (aw (0.901 by adding sucrose and sodium benzoate (0.1% as antimicrobial. SPT was stored under refrigeration (4 °C conditions protected from light and it was analyzed every third day for 60 days. Physicochemical (color, aw, pH, and titratable acidity as citric acid, antioxidant (antioxidant capacity, total phenolics, and anthocyanins, and microbiological (aerobic mesophilic bacteria, molds, and yeasts, were determined. SPT was mixed with plain yogurt to evaluate the overall sensory acceptance during storage. The evaluation took place every seventh day during 49 days. The storage time had no effect neither on aw, pH or acidity of the SPT. It was observed an increase in the net change of color (0 to 4.9 and a decrease in total phenolic compounds (1.213-0.816 mg gallic acid/g SPT, total monomeric anthocyanins (0.910-0.611 mg cyanidin-3-glucoside/g SPT g, and antioxidant capacity (5.816-3.576 µmole Trolox/g SPT. The aerobic mesophilic bacteria ( 0.05 during storage.

Holocene vegetation and fire history of the mountains of northern Sicily (Italy)

Science.gov (United States)

Tinner, Willy; Vescovi, Elisa; Van Leeuwen, Jacqueline; Colombaroli, Daniele; Henne, Paul; Kaltenrieder, Petra; Morales-Molino, Cesar; Beffa, Giorgia; Gnaegi, Bettina; Van der Knaap, Pim W O; La Mantia, Tommaso; Pasta, Salvatore

2016-01-01

Knowledge about vegetation and fire history of the mountains of Northern Sicily is scanty. We analysed five sites to fill this gap and used terrestrial plant macrofossils to establish robust radiocarbon chronologies. Palynological records from Gorgo Tondo, Gorgo Lungo, Marcato Cixé, Urgo Pietra Giordano and Gorgo Pollicino show that under natural or near natural conditions, deciduous forests (Quercus pubescens, Q. cerris, Fraxinus ornus, Ulmus), that included a substantial portion of evergreen broadleaved species (Q. suber, Q. ilex, Hedera helix), prevailed in the upper meso-mediterranean belt. Mesophilous deciduous and evergreen broadleaved trees (Fagus sylvatica, Ilex aquifolium) dominated in the natural or quasi-natural forests of the oro-mediterranean belt. Forests were repeatedly opened for agricultural purposes. Fire activity was closely associated with farming, providing evidence that burning was a primary land use tool since Neolithic times. Land use and fire activity intensified during the Early Neolithic at 5000 bc, at the onset of the Bronze Age at 2500 bc and at the onset of the Iron Age at 800 bc. Our data and previous studies suggest that the large majority of open land communities in Sicily, from the coastal lowlands to the mountain areas below the thorny-cushion Astragalus belt (ca. 1,800 m a.s.l.), would rapidly develop into forests if land use ceased. Mesophilous Fagus-Ilex forests developed under warm mid Holocene conditions and were resilient to the combined impacts of humans and climate. The past ecology suggests a resilience of these summer-drought adapted communities to climate warming of about 2 °C. Hence, they may be particularly suited to provide heat and drought-adaptedFagus sylvatica ecotypes for maintaining drought-sensitive Central European beech forests under global warming conditions.

Phylogenetic comparison of the methanogenic communities from an acidic, oligotrophic fen and an anaerobic digester treating municipal wastewater sludge.

Science.gov (United States)

Steinberg, Lisa M; Regan, John M

2008-11-01

Methanogens play a critical role in the decomposition of organics under anaerobic conditions. The methanogenic consortia in saturated wetland soils are often subjected to large temperature fluctuations and acidic conditions, imposing a selective pressure for psychro- and acidotolerant community members; however, methanogenic communities in engineered digesters are frequently maintained within a narrow range of mesophilic and circumneutral conditions to retain system stability. To investigate the hypothesis that these two disparate environments have distinct methanogenic communities, the methanogens in an oligotrophic acidic fen and a mesophilic anaerobic digester treating municipal wastewater sludge were characterized by creating clone libraries for the 16S rRNA and methyl coenzyme M reductase alpha subunit (mcrA) genes. A quantitative framework was developed to assess the differences between these two communities by calculating the average sequence similarity for 16S rRNA genes and mcrA within a genus and family using sequences of isolated and characterized methanogens within the approved methanogen taxonomy. The average sequence similarities for 16S rRNA genes within a genus and family were 96.0 and 93.5%, respectively, and the average sequence similarities for mcrA within a genus and family were 88.9 and 79%, respectively. The clone libraries of the bog and digester environments showed no overlap at the species level and almost no overlap at the family level. Both libraries were dominated by clones related to uncultured methanogen groups within the Methanomicrobiales, although members of the Methanosarcinales and Methanobacteriales were also found in both libraries. Diversity indices for the 16S rRNA gene library of the bog and both mcrA libraries were similar, but these indices indicated much lower diversity in the 16S digester library than in the other three libraries.

Characterization of three plant biomass-degrading microbial consortia by metagenomics- and metasecretomics-based approaches

DEFF Research Database (Denmark)

Jiménez, Diego Javier; Brossi, Maria Julia de Lima; Schückel, Julia

2016-01-01

). The highest degradation rates of lignin (~59 %) were observed with SG-M, whereas CS-M showed a high consumption of cellulose and hemicellulose. Analyses of the carbohydrate-active enzymes in the three microbial consortia showed the dominance of glycosyl hydrolases (e.g. of families GH3, GH43, GH13, GH10, GH29......), switchgrass (SG-M) and corn stover (CS-M) under aerobic and mesophilic conditions. Molecular fingerprintings, bacterial 16S ribosomal RNA (rRNA) gene amplicon sequencing and metagenomic analyses showed that the three microbial consortia were taxonomically distinct. Based on the taxonomic affiliation...

Macro algae as substrate for biogas production

DEFF Research Database (Denmark)

Møller, Henrik; Sarker, Shiplu; Gautam, Dhan Prasad

Algae as a substrate for biogas is superior to other crops since it has a much higher yield of biomass per unit area and since algae grows in the seawater there will be no competition with food production on agricultural lands. So far, the progress in treating different groups of algae as a source...... of energy is promising. In this study 5 different algae types were tested for biogas potential and two algae were subsequent used for co-digestion with manure. Green seaweed, Ulva lactuca and brown seaweed Laminaria digitata was co-digested with cattle manure at mesophilic and thermophilic condition...

ANAEROBIC BIOREMEDIATION OF PAH-CONTAMINATED SOIL: ASSESSMENT OF THE DEGRADATION OF CONTAMINANTS AND BIOGAS PRODUCTION UNDER THERMOPHILIC AND MESOPHILIC CONDITIONS

Czech Academy of Sciences Publication Activity Database

Sayara, T.; Čvančarová, Monika; Cajthaml, Tomáš; Sarra, M.; Sánchez, A.

2015-01-01

Roč. 14, č. 1 (2015), s. 153-165 ISSN 1582-9596 R&D Projects: GA ČR GA525/09/1058 Institutional support: RVO:61388971 Keywords : anaerobic digestion * central composite design * PAH-contaminated soil Subject RIV: EE - Microbiology, Virology Impact factor: 1.008, year: 2015

[Condition optimization for bio-oxidation of high-S and high-As gold concentrate].

Science.gov (United States)

Yang, Caiyun; Dong, Bowen; Wang, Meijun; Ye, Zhiyong; Zheng, Tianling; Huang, Huaiguo

2015-12-04

To study the effects of temperature and lixivium return on the concentrate bio-oxidation and rate of gold cyanide leaching. The bioleaching of a high-sulphur (S) and high-arsenic (As) refractory gold concentrate was conducted, and we studied the effects of different temperature (40 ° and 45 °C) and lixivium return (0 and 600 mL) on the bio-oxidation efficiency. The bacterial community structure also was investigated by 16S rRNA gene clone library. The results showed that both the temperature and lixivium return significantly influenced the oxidation system. The temperature rising elevated the oxidation level, while the addition of lixivium depressed the oxidation. Dissimilarity and DCA (detrended correspondence analysis) indicated the effect of temperature on oxidation system was much greater than lixivium. The bacterial community was comprised by Acidithiocacillus caldu (71%) Leptospirillum ferriphilum (23%) and Sulfobacillus thermosulfidooxidans (6%) indicated by the clone library, and the OTU coverage based on 97% sequence similarity was as high as 93.67%. Temperature rising to 45 T would improve the oxidation efficiency while lixivium return would decrease it. This study is helpful to provide an important guiding value for the industry cost optimization of mesophile bacterial oxidation and reduction process.

Microbiological Safety of Kitchen Sponges Used in Food Establishments

Directory of Open Access Journals (Sweden)

Tesfaye Wolde

2016-01-01

Full Text Available Kitchen sponges are among the possible sources of contaminants in food establishments. The main purpose of the current study was, therefore, to assess the microbiological safety of sponges as it has been used in selected food establishments of Jimma town. Accordingly, the microbiological safety of a total of 201 kitchen sponges randomly collected from food establishments was evaluated against the total counts of aerobic mesophilic bacteria (AMB, Enterobacteriaceae, coliforms, and yeast and molds. The mean counts of aerobic mesophilic bacteria ranged from 7.43 to 12.44 log CFU/mm3. The isolated genera were dominated by Pseudomonas (16.9%, Bacillus (11.1%, Micrococcus (10.6%, Streptococcus (7.8%, and Lactobacillus (6% excluding the unidentified Gram positive rods (4.9% and Gram negative rods (9.9%. The high microbial counts (aerobic mesophilic bacteria, coliforms, Enterobacteriaceae, and yeast and molds reveal the existence of poor kitchen sponge sanitization practice. Awareness creation training on basic hygienic practices to food handlers and periodic change of kitchen sponges are recommended.

Multiple Syntrophic Interactions in a Terephthalate-Degrading Methanogenic Consortium

Energy Technology Data Exchange (ETDEWEB)

Lykidis, Athanasios; Chen, Chia-Lung; Tringe, Susannah G.; McHardy, Alice C.; Copeland, Alex 5; Kyrpides, Nikos C.; Hugenholtz, Philip; Liu, Wen-Tso

2010-08-05

Terephthalate (TA) is one of the top 50 chemicals produced worldwide. Its production results in a TA-containing wastewater that is treated by anaerobic processes through a poorly understood methanogenic syntrophy. Using metagenomics, we characterized the methanogenic consortium tinside a hyper-mesophilic (i.e., between mesophilic and thermophilic), TA-degrading bioreactor. We identified genes belonging to dominant Pelotomaculum species presumably involved in TA degradation through decarboxylation, dearomatization, and modified ?-oxidation to H{sub 2}/CO{sub 2} and acetate. These intermediates are converted to CH{sub 4}/CO{sub 2} by three novel hyper-mesophilic methanogens. Additional secondary syntrophic interactions were predicted in Thermotogae, Syntrophus and candidate phyla OP5 and WWE1 populations. The OP5 encodes genes capable of anaerobic autotrophic butyrate production and Thermotogae, Syntrophus and WWE1 have the genetic potential to oxidize butyrate to COsub 2}/H{sub 2} and acetate. These observations suggest that the TA-degrading consortium consists of additional syntrophic interactions beyond the standard H{sub 2}-producing syntroph ? methanogen partnership that may serve to improve community stability.

Biogas from mesophilic digestion of cow dung using charcoal and gelatin as additives

Science.gov (United States)

Islam, Md Rashedul; Salam, Bodius; Rahman, Md Mizanur; Mamun, Abdullah Al

2017-06-01

Biogas, a source of renewable energy is produced from bacteria in the process of biodegradation of organic matter under anaerobic conditions. A research work was performed to find out the production of biogas from cow dung using charcoal and gelatin as additives. Five laboatory scale experimental set-up were constructed using 0, 0.2, 0.4, 0.6 and 0.8% gelatin with cow dung as additive to perform the research work. For all the set-up 0.5% charcoal was also added. All the set-ups were made from 1-liter capacity conical flask. The amount of water and cow dung was used respectively 382 gm. and 318 gm. in every set-up. Total solid content was maintained 8% throughout all set-ups. The digesters were operated at ambient temperature of 26°-32°C. The total gas yield without using gelatin additive was found to be 12 L/kg cow dung. The maximum gas yield was found from 0.2% gelatin additive and 23% more as compared to without gelatin gas production. The retention time varied from 28 to 79 days for the experiments.

Anaerobic solid state fermentation of cellulosic substrates with possible application to cellulase production

Energy Technology Data Exchange (ETDEWEB)

Vandevoorde, L; Verstraete, W

1987-08-01

A solid state fermentation process was developed for the conversion of straw and cellulose under anaerobic conditions by a mixed culture of cellulolytic and methanogenic organisms. The bioconversion rate and efficiency were compared under mesophilic (35/sup 0/C) and thermophilic (55/sup 0/C) conditions. Cellulolytic activity was assayed in terms of sugar and overall soluble organic matter (chemical oxygen demand, COD) production. Maximum conversion rates were obtained under thermophilic conditions, i.e. 8.4 g and 14.2 g COD/kg.d, respectively, when wheat straw and cellulose were used as substrates. The cellulolytic activity of the reactor contents (23% dry matter), measured under substrate excess conditions, amounted to 50 g COD/kg.d. As a comparison, the activity of rumen contents (15 % dry matter) measured by the same assay amounted to 150 g COD/kg . d. The anaerobic cellulases appeared to be substrate bound. This and the relative low activity levels attained, limit the perspectives of producing cellulase enzymes by this type of process.

Electron transport chain in a thermotolerant yeast.

Science.gov (United States)

Mejía-Barajas, Jorge A; Martínez-Mora, José A; Salgado-Garciglia, Rafael; Noriega-Cisneros, Ruth; Ortiz-Avila, Omar; Cortés-Rojo, Christian; Saavedra-Molina, Alfredo

2017-04-01

Yeasts capable of growing and surviving at high temperatures are regarded as thermotolerant. For appropriate functioning of cellular processes and cell survival, the maintenance of an optimal redox state is critical of reducing and oxidizing species. We studied mitochondrial functions of the thermotolerant Kluyveromyces marxianus SLP1 and the mesophilic OFF1 yeasts, through the evaluation of its mitochondrial membrane potential (ΔΨ m ), ATPase activity, electron transport chain (ETC) activities, alternative oxidase activity, lipid peroxidation. Mitochondrial membrane potential and the cytoplasmic free Ca 2+ ions (Ca 2+ cyt) increased in the SLP1 yeast when exposed to high temperature, compared with the mesophilic yeast OFF1. ATPase activity in the mesophilic yeast diminished 80% when exposed to 40° while the thermotolerant SLP1 showed no change, despite an increase in the mitochondrial lipid peroxidation. The SLP1 thermotolerant yeast exposed to high temperature showed a diminution of 33% of the oxygen consumption in state 4. The uncoupled state 3 of oxygen consumption did not change in the mesophilic yeast when it had an increase of temperature, whereas in the thermotolerant SLP1 yeast resulted in an increase of 2.5 times when yeast were grown at 30 o , while a decrease of 51% was observed when it was exposed to high temperature. The activities of the ETC complexes were diminished in the SLP1 when exposed to high temperature, but also it was distinguished an alternative oxidase activity. Our results suggest that the mitochondria state, particularly ETC state, is an important characteristic of the thermotolerance of the SLP1 yeast strain.

Quantitative effects of composting state variables on C/N ratio through GA-aided multivariate analysis

International Nuclear Information System (INIS)

Sun Wei; Huang, Guo H.; Zeng Guangming; Qin Xiaosheng; Yu Hui

2011-01-01

It is widely known that variation of the C/N ratio is dependent on many state variables during composting processes. This study attempted to develop a genetic algorithm aided stepwise cluster analysis (GASCA) method to describe the nonlinear relationships between the selected state variables and the C/N ratio in food waste composting. The experimental data from six bench-scale composting reactors were used to demonstrate the applicability of GASCA. Within the GASCA framework, GA searched optimal sets of both specified state variables and SCA's internal parameters; SCA established statistical nonlinear relationships between state variables and the C/N ratio; to avoid unnecessary and time-consuming calculation, a proxy table was introduced to save around 70% computational efforts. The obtained GASCA cluster trees had smaller sizes and higher prediction accuracy than the conventional SCA trees. Based on the optimal GASCA tree, the effects of the GA-selected state variables on the C/N ratio were ranged in a descending order as: NH 4 + -N concentration > Moisture content > Ash Content > Mean Temperature > Mesophilic bacteria biomass. Such a rank implied that the variation of ammonium nitrogen concentration, the associated temperature and the moisture conditions, the total loss of both organic matters and available mineral constituents, and the mesophilic bacteria activity, were critical factors affecting the C/N ratio during the investigated food waste composting. This first application of GASCA to composting modelling indicated that more direct search algorithms could be coupled with SCA or other multivariate analysis methods to analyze complicated relationships during composting and many other environmental processes. - Research Highlights: → A genetic algorithm aided stepwise cluster analysis method in food waste composting. → Nonlinear relationships between the selected state variables and the C/N ratio. → Introduced proxy tables save around 70% computational

Utilization of buffered vinegar to increase the shelf life of chicken retail cuts packaged in carbon dioxide.

Science.gov (United States)

Desai, Monil A; Kurve, Vikram; Smith, Brian S; Campano, Stephen G; Soni, Kamlesh; Schilling, M Wes

2014-07-01

Poultry processors commonly place whole parts of broilers in plastic packages and seal them in an atmosphere of 100% carbon dioxide before shipping them to food service and retail customers. This practice extends the shelf life of retail cuts to approximately 12 d under refrigerated conditions. The objective of this study was to determine the antimicrobial efficacy of vinegar for growth inhibition of mesophilic and lactic acid bacterial counts and enhancement of shelf life in CO2-packaged refrigerated chicken thigh samples. Meat quality, sensory differences, and microbial enumeration were evaluated for chicken thighs that were sprayed with 0, 0.5, or 1.0% vinegar. No differences were observed (P > 0.05) among treatments (control vs. 0.5 and 1.0% vinegar-treated chicken thighs) with respect to pH and Commission Internationale d'Eclairage L*a*b*for both chicken skin and the meat tissue. The difference from the control test indicated that trained panelists were not able to detect a difference (P > 0.05) in flavor between the chicken thigh treatments. The mesophilic and Lactobacillus bacterial counts were enumerated after 0, 4, 8, 12, 16, and 20 d of storage. The mesophilic bacterial load for the 1.0% vinegar treatment was less than all other treatments after 8, 12, 16, and 20 d of storage, whereas the 0.5% vinegar treatment had lower bacterial counts at d 12 than both controls and had an approximate shelf life of 16 d. For lactic acid bacteria, the vinegar 1.0% treatment had lower counts than the control treatments at d 12 and 16. The results from the study indicate that a combination of 1.0% vinegar with CO2 packaging can extend the shelf life from 12 to 20 d for chicken retail cuts without negatively affecting the quality and sensory properties of the broiler meat. © 2014 Poultry Science Association Inc.

Quantitative effects of composting state variables on C/N ratio through GA-aided multivariate analysis

Energy Technology Data Exchange (ETDEWEB)

Sun Wei [Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada); Huang, Guo H., E-mail: huangg@iseis.org [Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada); MOE Key Laboratory of Regional Energy Systems Optimization, Sino-Canada Energy and Environmental Research Academy, North China Electric Power University, Beijing, 102206 (China); Zeng Guangming [MOE Key Laboratory of Environmental Biology and Pollution Control, College of Environmental Science and Engineering, Hunan University, Changsha, Hunan, 410082 (China); Qin Xiaosheng [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yu Hui [Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan, S4S 0A2 (Canada)

2011-03-01

It is widely known that variation of the C/N ratio is dependent on many state variables during composting processes. This study attempted to develop a genetic algorithm aided stepwise cluster analysis (GASCA) method to describe the nonlinear relationships between the selected state variables and the C/N ratio in food waste composting. The experimental data from six bench-scale composting reactors were used to demonstrate the applicability of GASCA. Within the GASCA framework, GA searched optimal sets of both specified state variables and SCA's internal parameters; SCA established statistical nonlinear relationships between state variables and the C/N ratio; to avoid unnecessary and time-consuming calculation, a proxy table was introduced to save around 70% computational efforts. The obtained GASCA cluster trees had smaller sizes and higher prediction accuracy than the conventional SCA trees. Based on the optimal GASCA tree, the effects of the GA-selected state variables on the C/N ratio were ranged in a descending order as: NH{sub 4}{sup +}-N concentration > Moisture content > Ash Content > Mean Temperature > Mesophilic bacteria biomass. Such a rank implied that the variation of ammonium nitrogen concentration, the associated temperature and the moisture conditions, the total loss of both organic matters and available mineral constituents, and the mesophilic bacteria activity, were critical factors affecting the C/N ratio during the investigated food waste composting. This first application of GASCA to composting modelling indicated that more direct search algorithms could be coupled with SCA or other multivariate analysis methods to analyze complicated relationships during composting and many other environmental processes. - Research Highlights: {yields} A genetic algorithm aided stepwise cluster analysis method in food waste composting. {yields} Nonlinear relationships between the selected state variables and the C/N ratio. {yields} Introduced proxy tables

Community size and metabolic rates of psychrophilic sulfate-reducing bacteria in Arctic marine sediments

DEFF Research Database (Denmark)

Knoblauch, C.; Jørgensen, BB; Harder, J.

1999-01-01

The numbers of sulfate reducers in two Arctic sediments within situ temperatures of 2.6 and -1.7 degrees C were determined. Most-probable-number counts were higher at 10 degrees C than at 20 degrees C, indicating the predominance of a psychrophilic community. Mean specific sulfate reduction rates...... of 19 isolated psychrophiles were compared to corresponding rates of 9 marine, mesophilic sulfate-reducing bacteria. The results indicate that, as a physiological adaptation to the permanently cold Arctic environment, psychrophilic sulfate reducers have considerably higher specific metabolic rates than...... their mesophilic counterparts at similarly low temperatures....

Effect of low dose irradiation of pork loins on the microflora, sensory characteristics and fat stability

International Nuclear Information System (INIS)

Mattison, M.L.; Kraft, A.A.; Olson, D.G.; Walker, H.W.; Rust, R.E.; James, D.B.

1986-01-01

The effects of low dose (100 krad) irradiation on microflora, sensory characteristics, and development of oxidative rancidity of vacuum packaged pork loins was investigated after irradiation and during low temperature (4 0 C) storage up to 21 days. Irradiation reduced numbers of mesophiles, psychrotrophs, anaerobic bacteria (P<0.01), and staphylococci (P<0.05), with the effect on mesophiles and psychrotrophic spoilage organisms the greatest. Effect of irradiation on sensory characteristics of pork loin was minimal with no detectable differences between irradiated and nonirradiated pork after 14 days of storage. Irradiation of pork did not affect cooking loss or thiobarbituric acid values

Effect of irradiation on shelf - life and quality characteristics of two (2) solanum species

International Nuclear Information System (INIS)

Riverson, N. M

2013-07-01

Garden eggs (solanum spp) are grown as a commercial crop for domestic consumption and also for export. In addition to major production challenges such as limited shelf-life, poor post-harvest handling and the lack of quality standards, garden eggs are prone to infection by pest and diseases at all stages of growth. This theses provides information on the effect of gamma radiation doses (1 - 3kGy) on the shelf life and some quality characteristics of three varieties of garden eggs Solanum aethiopicum GH 8772 and aethiopicum GH 8773, and aethiopicum torvum under two packaging conditions. Quality attributes of colour, firmness, and wrinkleness were assessed using a nine-point hedonic scale in decreasing order of acceptability. The numbers of rotten fruits were recorded on weekly basis throughout the storage period of four weeks. The physiochemical properties (moisture content, weight loss and pH) were determined by standard methods. The microbiological quality was assessed by estimating the population of aerobic mesophiles and yeast and moulds using the methods of serial dilution and pour plating. The three varieties of garden eggs used in the study responded differently to gamma radiation and storage. Salannum torvum showed discolouration and subsequent fungal spoilage in the first week of storage after irradiation under both unpackaged and packaged conditions; howbeit the unirradiated had acceptable scores (>4.33) in terms of colour, firmness, and wrinkleness throughout the storage period. At the end of the storage period samples of S. torvum had lower values in terms of moisture (26.78%), weight loss (9.3 g) and pH (2.9) under unpackaged condition, but high vitamin C content of 14.83 mg/100g. Samples S. torvum under packaged conditions had higher values in terms of colour, firmness, and wrinkleness as well as pH and vitamin C. However the effect of packaging was not significant with respect to the quality attributes and physiochemical properties. Decline in colour

Cold adaptation of the mononuclear molybdoenzyme periplasmic nitrate reductase from the Antarctic bacterium Shewanella gelidimarina

Energy Technology Data Exchange (ETDEWEB)

Simpson, Philippa J.L. [School of Chemistry, University of Sydney, New South Wales 2006 (Australia); Codd, Rachel, E-mail: rachel.codd@sydney.edu.au [School of Chemistry, University of Sydney, New South Wales 2006 (Australia); School of Medical Sciences (Pharmacology) and Bosch Institute, University of New South Wales, New South Wales 2006 (Australia)

2011-11-04

Highlights: Black-Right-Pointing-Pointer Cold-adapted phenotype of NapA from the Antarctic bacterium Shewanella gelidimarina. Black-Right-Pointing-Pointer Protein homology model of NapA from S. gelidimarina and mesophilic homologue. Black-Right-Pointing-Pointer Six amino acid residues identified as lead candidates governing NapA cold adaptation. Black-Right-Pointing-Pointer Molecular-level understanding of designing cool-temperature in situ oxyanion sensors. -- Abstract: The reduction of nitrate to nitrite is catalysed in bacteria by periplasmic nitrate reductase (Nap) which describes a system of variable protein subunits encoded by the nap operon. Nitrate reduction occurs in the NapA subunit, which contains a bis-molybdopterin guanine dinucleotide (Mo-MGD) cofactor and one [4Fe-4S] iron-sulfur cluster. The activity of periplasmic nitrate reductase (Nap) isolated as native protein from the cold-adapted (psychrophilic) Antarctic bacterium Shewanella gelidimarina (Nap{sub Sgel}) and middle-temperature adapted (mesophilic) Shewanella putrefaciens (Nap{sub Sput}) was examined at varied temperature. Irreversible deactivation of Nap{sub Sgel} and Nap{sub Sput} occurred at 54.5 and 65 Degree-Sign C, respectively. When Nap{sub Sgel} was preincubated at 21-70 Degree-Sign C for 30 min, the room-temperature nitrate reductase activity was maximal and invariant between 21 and 54 Degree-Sign C, which suggested that Nap{sub Sgel} was poised for optimal catalysis at modest temperatures and, unlike Nap{sub Sput}, did not benefit from thermally-induced refolding. At 20 Degree-Sign C, Nap{sub Sgel} reduced selenate at 16% of the rate of nitrate reduction. Nap{sub Sput} did not reduce selenate. Sequence alignment showed 46 amino acid residue substitutions in Nap{sub Sgel} that were conserved in NapA from mesophilic Shewanella, Rhodobacter and Escherichia species and could be associated with the Nap{sub Sgel} cold-adapted phenotype. Protein homology modeling of Nap{sub Sgel} using a

Cold adaptation of the mononuclear molybdoenzyme periplasmic nitrate reductase from the Antarctic bacterium Shewanella gelidimarina

International Nuclear Information System (INIS)

Simpson, Philippa J.L.; Codd, Rachel

2011-01-01

Highlights: ► Cold-adapted phenotype of NapA from the Antarctic bacterium Shewanella gelidimarina. ► Protein homology model of NapA from S. gelidimarina and mesophilic homologue. ► Six amino acid residues identified as lead candidates governing NapA cold adaptation. ► Molecular-level understanding of designing cool-temperature in situ oxyanion sensors. -- Abstract: The reduction of nitrate to nitrite is catalysed in bacteria by periplasmic nitrate reductase (Nap) which describes a system of variable protein subunits encoded by the nap operon. Nitrate reduction occurs in the NapA subunit, which contains a bis-molybdopterin guanine dinucleotide (Mo–MGD) cofactor and one [4Fe–4S] iron–sulfur cluster. The activity of periplasmic nitrate reductase (Nap) isolated as native protein from the cold-adapted (psychrophilic) Antarctic bacterium Shewanella gelidimarina (Nap Sgel ) and middle-temperature adapted (mesophilic) Shewanella putrefaciens (Nap Sput ) was examined at varied temperature. Irreversible deactivation of Nap Sgel and Nap Sput occurred at 54.5 and 65 °C, respectively. When Nap Sgel was preincubated at 21–70 °C for 30 min, the room-temperature nitrate reductase activity was maximal and invariant between 21 and 54 °C, which suggested that Nap Sgel was poised for optimal catalysis at modest temperatures and, unlike Nap Sput , did not benefit from thermally-induced refolding. At 20 °C, Nap Sgel reduced selenate at 16% of the rate of nitrate reduction. Nap Sput did not reduce selenate. Sequence alignment showed 46 amino acid residue substitutions in Nap Sgel that were conserved in NapA from mesophilic Shewanella, Rhodobacter and Escherichia species and could be associated with the Nap Sgel cold-adapted phenotype. Protein homology modeling of Nap Sgel using a mesophilic template with 66% amino acid identity showed the majority of substitutions occurred at the protein surface distal to the Mo–MGD cofactor. Two mesophilic ↔ psychrophilic

Anaerobic digestion of spent mushroom substrate under thermophilic conditions: performance and microbial community analysis.

Science.gov (United States)

Xiao, Zheng; Lin, Manhong; Fan, Jinlin; Chen, Yixuan; Zhao, Chao; Liu, Bin

2018-01-01

Spent mushroom substrate (SMS) is the residue of edible mushroom production occurring in huge amounts. The SMS residue can be digested for biogas production in the mesophilic anaerobic digestion. In the present study, performance of batch thermophilic anaerobic digestion (TAD) of SMS was investigated as well as the interconnected microbial population structure changes. The analyzed batch TAD process lasted for 12 days with the cumulative methane yields of 177.69 mL/g volatile solid (VS). Hydrolytic activities of soluble sugar, crude protein, and crude fat in SMS were conducted mainly in the initial phase, accompanied by the excessive accumulation of volatile fatty acids and low methane yield. Biogas production increased dramatically from days 4 to 6. The degradation rates of cellulose and hemicellulose were 47.53 and 55.08%, respectively. The high-throughput sequencing of 16S rRNA gene amplicons revealed that Proteobacteria (56.7%-62.8%) was the dominant phylum in different fermentative stages, which was highly specific compared with other anaerobic processes of lignocellulosic materials reported in the literature. Crenarchaeota was abundant in the archaea. The most dominant genera of archaea were retrieved as Methanothermobacter and Methanobacterium, but the latter decreased sharply with time. This study shows that TAD is a feasible method to handle the waste SMS.

Alteration of protein patterns in black rock inhabiting fungi as a response to different temperatures

Science.gov (United States)

Tesei, Donatella; Marzban, Gorji; Zakharova, Kristina; Isola, Daniela; Selbmann, Laura; Sterflinger, Katja

2012-01-01

Rock inhabiting fungi are among the most stress tolerant organisms on Earth. They are able to cope with different stressors determined by the typical conditions of bare rocks in hot and cold extreme environments. In this study first results of a system biological approach based on two-dimensional protein profiles are presented. Protein patterns of extremotolerant black fungi – Coniosporium perforans, Exophiala jeanselmei – and of the extremophilic fungus – Friedmanniomyces endolithicus – were compared with the cosmopolitan and mesophilic hyphomycete Penicillium chrysogenum in order to follow and determine changes in the expression pattern under different temperatures. The 2D protein gels indicated a temperature dependent qualitative change in all the tested strains. Whereas the reference strain P. chrysogenum expressed the highest number of proteins at 40 °C, thus exhibiting real signs of temperature induced reaction, black fungi, when exposed to temperatures far above their growth optimum, decreased the number of proteins indicating a down-regulation of their metabolism. Temperature of 1 °C led to an increased number of proteins in all of the analysed strains, with the exception of P. chrysogenum. These first results on temperature dependent reactions in rock inhabiting black fungi indicate a rather different strategy to cope with non-optimal temperature than in the mesophilic hyphomycete P. chrysogenum. PMID:22862921

Mesophilic and psychrophilic digestion of liquid manure

NARCIS (Netherlands)

Zeeman, G.

1991-01-01

IN GENERAL

In this thesis the possibilities for digestion of cow and pig manure are described for a completely stirred tank reactor system (CSTR) and an accumulation system (AC-system).
For this purpose were researched:
1. Anaerobic digestion

Comparative Analysis of Performance and Microbial Characteristics Between High-Solid and Low-Solid Anaerobic Digestion of Sewage Sludge Under Mesophilic Conditions.

Science.gov (United States)

Lu, Qin; Yi, Jing; Yang, Dianhai

2016-01-01

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 high-throughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

Condition Indicators for Gearbox Condition Monitoring Systems

Directory of Open Access Journals (Sweden)

P. Večeř

2005-01-01

Full Text Available Condition monitoring systems for manual transmissions based on vibration diagnostics are widely applied in industry. The systems deal with various condition indicators, most of which are focused on a specific type of gearbox fault. Frequently used condition indicators (CIs are described in this paper. The ability of a selected condition indicator to describe the degree of gearing wear was tested using vibration signals acquired during durability testing of manual transmission with helical gears. 

Viral Diversity Threshold for Adaptive Immunity in Prokaryotes

Science.gov (United States)

Weinberger, Ariel D.; Wolf, Yuri I.; Lobkovsky, Alexander E.; Gilmore, Michael S.; Koonin, Eugene V.

2012-01-01

ABSTRACT Bacteria and archaea face continual onslaughts of rapidly diversifying viruses and plasmids. Many prokaryotes maintain adaptive immune systems known as clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated genes (Cas). CRISPR-Cas systems are genomic sensors that serially acquire viral and plasmid DNA fragments (spacers) that are utilized to target and cleave matching viral and plasmid DNA in subsequent genomic invasions, offering critical immunological memory. Only 50% of sequenced bacteria possess CRISPR-Cas immunity, in contrast to over 90% of sequenced archaea. To probe why half of bacteria lack CRISPR-Cas immunity, we combined comparative genomics and mathematical modeling. Analysis of hundreds of diverse prokaryotic genomes shows that CRISPR-Cas systems are substantially more prevalent in thermophiles than in mesophiles. With sequenced bacteria disproportionately mesophilic and sequenced archaea mostly thermophilic, the presence of CRISPR-Cas appears to depend more on environmental temperature than on bacterial-archaeal taxonomy. Mutation rates are typically severalfold higher in mesophilic prokaryotes than in thermophilic prokaryotes. To quantitatively test whether accelerated viral mutation leads microbes to lose CRISPR-Cas systems, we developed a stochastic model of virus-CRISPR coevolution. The model competes CRISPR-Cas-positive (CRISPR-Cas+) prokaryotes against CRISPR-Cas-negative (CRISPR-Cas−) prokaryotes, continually weighing the antiviral benefits conferred by CRISPR-Cas immunity against its fitness costs. Tracking this cost-benefit analysis across parameter space reveals viral mutation rate thresholds beyond which CRISPR-Cas cannot provide sufficient immunity and is purged from host populations. These results offer a simple, testable viral diversity hypothesis to explain why mesophilic bacteria disproportionately lack CRISPR-Cas immunity. More generally, fundamental limits on the adaptability of biological

Development of a gene cloning system in a fast-growing and moderately thermophilic Streptomyces species and heterologous expression of Streptomyces antibiotic biosynthetic gene clusters

Science.gov (United States)

2011-01-01

Background Streptomyces species are a major source of antibiotics. They usually grow slowly at their optimal temperature and fermentation of industrial strains in a large scale often takes a long time, consuming more energy and materials than some other bacterial industrial strains (e.g., E. coli and Bacillus). Most thermophilic Streptomyces species grow fast, but no gene cloning systems have been developed in such strains. Results We report here the isolation of 41 fast-growing (about twice the rate of S. coelicolor), moderately thermophilic (growing at both 30°C and 50°C) Streptomyces strains, detection of one linear and three circular plasmids in them, and sequencing of a 6996-bp plasmid, pTSC1, from one of them. pTSC1-derived pCWH1 could replicate in both thermophilic and mesophilic Streptomyces strains. On the other hand, several Streptomyces replicons function in thermophilic Streptomyces species. By examining ten well-sporulating strains, we found two promising cloning hosts, 2C and 4F. A gene cloning system was established by using the two strains. The actinorhodin and anthramycin biosynthetic gene clusters from mesophilic S. coelicolor A3(2) and thermophilic S. refuineus were heterologously expressed in one of the hosts. Conclusions We have developed a gene cloning and expression system in a fast-growing and moderately thermophilic Streptomyces species. Although just a few plasmids and one antibiotic biosynthetic gene cluster from mesophilic Streptomyces were successfully expressed in thermophilic Streptomyces species, we expect that by utilizing thermophilic Streptomyces-specific promoters, more genes and especially antibiotic genes clusters of mesophilic Streptomyces should be heterologously expressed. PMID:22032628

Suitability of biocompost as a bedding material for stabled horses: respiratory hygiene and management practicalities.

Science.gov (United States)

Seedorf, J; Schröder, M; Köhler, L; Hartung, J

2007-03-01

Bedding material in stables has an important influence on air hygiene and information on the suitability of biocompost and wood shavings is incomplete. To compare the suitability and benefit of biocompost and wood shavings as bedding in horse stables and to determine key air factors for the evaluation of the potential impact of these materials on respiratory health. The study was conducted in a naturally ventilated stable with 4 horses. Air hygiene parameters were measured 24 h/day for 7 days with each bedding type: ammonia (NH3), inhalable and respirable dust, endotoxins, colony forming units (CFU) of total mesophilic bacteria, fungi, actinomycetes and thermophilic actinomycetes. Both bedding materials were analysed for general chemical composition, particle size distribution and natural microbial content. The animals' behaviour was monitored by video cameras, and their health and cleanliness status determined by clinical and visual examination. Concentrations of NH3, dust, endoxins and fungi were significantly higher during the monitoring period with wood shavings than with biocompost. In contrast concentrations of mesophilic bacteria, mesophilic actinomycetes and thermophilic actinomycetes microbial pollutants were highest with biocompost. The water content of bulk biocompost was considerably higher than that of wood shavings. Particles market.

Deanne W. Sammond | NREL

Science.gov (United States)

"Comparing Residue Clusters from Thermophilic and Mesophilic Enzymes Reveals Adaptive Mechanisms improving the function of cellulases Consolidated bioprocessing-engineering thermophilic bacteria to produce

Exploring optimal conditions for thermophilic fermentative hydrogen production from cassava stillage

Energy Technology Data Exchange (ETDEWEB)

Luo, Gang; Zou, Zhonghai; Wang, Wen [Key Laboratory of Yangtze River Water Environment, Ministry(Tongji University), Siping Road no 1239, Shanghai 200092 (China); Xie, Li; Zhou, Qi [Key Laboratory of Yangtze River Water Environment, Ministry(Tongji University), Siping Road no 1239, Shanghai 200092 (China); UNEP-Tongji University Institute of Environment for Sustainable Development, Siping Road no 1239, Shanghai 200092 (China)

2010-06-15

This study investigated the effects of seed sludges, alkalinity and HRT on the thermophilic fermentative hydrogen production from cassava stillage. Five different kinds of sludges were used as inocula without any pretreatment. Though batch experiments showed that mesophilic anaerobic sludge was the best inoculum, the hydrogen yields with different seed sludges were quite similar in continuous experiments in the range of 82.9-92.3 ml H{sub 2}/gVS without significant differences which could be attributed to the establishment of Uncultured Thermoanaerobacteriaceae bacterium-dominant microbial communities in all reactors. It is indicated that results obtained from batch experiments are not consistent with those from continuous experiments and all the tested seed sludges are good sources for continuous thermophilic hydrogen production from cassava stillage. The influent alkalinity of 6 g NaHCO{sub 3}/L and HRT 24 h were optimal for hydrogen production with hydrogen yield of 76 ml H{sub 2}/gVS and hydrogen production rate of 3215 ml H{sub 2}/L/d. Butyrate was the predominant metabolite in all experiments. With the increase in alkalinity of more than 6 g/L, the concentration of VFA/ethanol increased while hydrogen yield decreased due to the higher concentration of acetate and propionate. The decrease in HRT resulted in the higher hydrogen production rate but lower hydrogen yield. Variation of hydrogen yields were quite correlated with butyrate/acetate (B/A) ratio with different influent alkalinities, however, butyrate was important parameter to justify the hydrogen yields with various HRTs. (author)

Evolution of quality characteristics of minimally processed asparagus during storage in different lighting conditions.

Science.gov (United States)

Sanz, S; Olarte, C; Ayala, F; Echávarri, J F

2009-08-01

The effect of different types of lighting (white, green, red, and blue light) on minimally processed asparagus during storage at 4 degrees C was studied. The gas concentrations in the packages, pH, mesophilic counts, and weight loss were also determined. Lighting caused an increase in physiological activity. Asparagus stored under lighting achieved atmospheres with higher CO(2) and lower O(2) content than samples kept in the dark. This activity increase explains the greater deterioration experienced by samples stored under lighting, which clearly affected texture and especially color, accelerating the appearance of greenish hues in the tips and reddish-brown hues in the spears. Exposure to light had a negative effect on the quality parameters of the asparagus and it caused a significant reduction in shelf life. Hence, the 11 d shelf life of samples kept in the dark was reduced to only 3 d in samples kept under red and green light, and to 7 d in those kept under white and blue light. However, quality indicators such as the color of the tips and texture showed significantly better behavior under blue light than with white light, which allows us to state that it is better to use this type of light or blue-tinted packaging film for the display of minimally processed asparagus to consumers.

Ultrasonic disintegration of microalgal biomass and consequent improvement of bioaccessibility/bioavailability in microbial fermentation.

Science.gov (United States)

Jeon, Byong-Hun; Choi, Jeong-A; Kim, Hyun-Chul; Hwang, Jae-Hoon; Abou-Shanab, Reda Ai; Dempsey, Brian A; Regan, John M; Kim, Jung Rae

2013-01-01

Microalgal biomass contains a high level of carbohydrates which can be biochemically converted to biofuels using state-of-the-art strategies that are almost always needed to employ a robust pretreatment on the biomass for enhanced energy production. In this study, we used an ultrasonic pretreatment to convert microalgal biomass (Scenedesmus obliquus YSW15) into feasible feedstock for microbial fermentation to produce ethanol and hydrogen. The effect of sonication condition was quantitatively evaluated with emphases on the characterization of carbohydrate components in microalgal suspension and on subsequent production of fermentative bioenergy. Scenedesmus obliquus YSW15 was isolated from the effluent of a municipal wastewater treatment plant. The sonication durations of 0, 10, 15, and 60 min were examined under different temperatures at a fixed frequency and acoustic power resulted in morphologically different states of microalgal biomass lysis. Fermentation was performed to evaluate the bioenergy production from the non-sonicated and sonicated algal biomasses after pretreatment stage under both mesophilic (35°C) and thermophilic (55°C) conditions. A 15 min sonication treatment significantly increased the concentration of dissolved carbohydrates (0.12 g g(-1)), which resulted in an increase of hydrogen/ethanol production through microbial fermentation. The bioconvertibility of microalgal biomass sonicated for 15 min or longer was comparable to starch as a control, indicating a high feasibility of using microalgae for fermentative bioenergy production. Increasing the sonication duration resulted in increases in both algal surface hydrophilicity and electrostatic repulsion among algal debris dispersed in aqueous solution. Scanning electron microscope images supported that ruptured algal cell allowed fermentative bacteria to access the inner space of the cell, evidencing an enhanced bioaccessibility. Sonication for 15 min was the best for fermentative

Development of a combined bio-hydrogen- and methane-production unit using dark fermentation

Energy Technology Data Exchange (ETDEWEB)

Brunstermann, R.; Widmann, R. [Duisburg-Essen Univ. (Germany). Dept. of Urban Water and Waste Management

2010-07-01

Hydrogen is regarded as a source of energy of the future. Currently, hydrogen is produced, predominantly, by electrolysis of water by using electricity or by stream reforming of natural gas. So both methods are based on fossil fuels. If the used electricity is recovered from renewable recourses, hydrogen produced by water electrolysis may be a clean solution. At present, the production of hydrogen by biological processes finds more and more attention world far. The biology provides a wide range of approaches to produce hydrogen, including bio-photolysis as well as photo-fermentation and dark-fermentation. Currently these biological technologies are not suitable for solving every day energy problems [1]. But the dark-fermentation is a promising approach to produce hydrogen in a sustainable way and was already examined in some projects. At mesophilic conditions this process provides a high yield of hydrogen by less energy demand, [2]. Short hydraulic retention times (HRT) and high metabolic rates are advantages of the process. The incomplete transformation of the organic components into various organic acids is a disadvantage. Thus a second process step is required. Therefore the well known biogas-technique is used to degrade the organic acids predominantly acetic and butyric acid from the hydrogen-production unit into CH{sub 4} and CO{sub 2}. This paper deals with the development of a combined hydrogen and methane production unit using dark fermentation at mesophilic conditions. The continuous operation of the combined hydrogen and methane production out of DOC loaded sewages and carbohydrate rich biowaste is necessary for the examination of the technical and economical implementation. The hydrogen step shows as first results hydrogen concentration in the biogas between 40 % and 60 %.The operating efficiency of the combined production of hydrogen and methane shall be checked as a complete system. (orig.)

Sequential treatment of diluted olive pomace leachate by digestion in a pilot scale UASB reactor and BDD electrochemical oxidation.

Science.gov (United States)

Katsoni, Alphathanasia; Mantzavinos, Dionissios; Diamadopoulos, Evan

2014-06-15

The efficiency of the anaerobic treatment of olive pomace leachate (OPL) at mesophilic conditions was investigated. Daily and cumulative biogas production was measured during the operational period. The maximum biogas flowrate was 65 L/d, of which 50% was methane. In addition, the applicability of electrochemical oxidation as an advanced post-treatment method for the complete removal of chemical oxygen demand (COD) from the anaerobically treated OPL was evaluated. The diluted OPL, having a pH of 6.5 and a total COD of 5 g/L, was first treated in a 600 L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor was operated for 71 days at mesophilic conditions (32 ± 2 °C) in a temperature-controlled environment at a hydraulic retention time of 3 days, and organic loading rates (OLR) between 0.33 and 1.67 g COD/(L.d). The UASB process led to a COD removal efficiency between 35 and 70%, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 18 A and in the presence of 0.17% NaCl as the supporting electrolyte, complete removal of COD was attained after 7 h of treatment predominantly through total oxidation reactions. During electrochemical experiments, three groups of organo-chlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs) and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, along with the residual chlorine are thought to increase the matrix ecotoxicity to Artemia salina. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of current operating standards for chlorine dioxide in disinfection of dump tank and flume for fresh tomatoes.

Science.gov (United States)

Tomás-Callejas, Alejandro; López-Velasco, Gabriela; Valadez, Angela M; Sbodio, Adrian; Artés-Hernández, Francisco; Danyluk, Michelle D; Suslow, Trevor V

2012-02-01

Standard postharvest unit operations that rely on copious water contact, such as fruit unloading and washing, approach the criteria for a true critical control point in fresh tomato production. Performance data for approved sanitizers that reflect commercial systems are needed to set standards for audit compliance. This study was conducted to evaluate the efficacy of chlorine dioxide (ClO(2)) for water disinfection as an objective assessment of recent industry-adopted standards for dump tank and flume management in fresh tomato packing operations. On-site assessments were conducted during eight temporally distinct shifts in two Florida packinghouses and one California packinghouse. Microbiological analyses of incoming and washed fruit and dump and flume system water were evaluated. Water temperature, pH, turbidity, conductivity, and oxidation-reduction potential (ORP) were monitored. Reduction in populations of mesophilic and coliform bacteria on fruit was not significant, and populations were significantly higher (P Turbidity and conductivity increased with loads of incoming tomatoes. Water temperature varied during daily operations, but pH and ORP mostly remained constant. The industry standard positive temperature differential of 5.5°C between water and fruit pulp was not maintained in tanks during the full daily operation. ORP values were significantly higher in the flume than in the dump tank. A positive correlation was found between ORP and temperature, and negative correlations were found between ORP and turbidity, total mesophilic bacteria, and coliforms. This study provides in-plant data indicating that ClO(2) can be an effective sanitizer in flume and spray-wash systems, but current operational limitations restrict its performance in dump tanks. Under current conditions, ClO(2) alone is unlikely to allow the fresh tomato industry to meet its microbiological quality goals under typical commercial conditions.

Influence of temperature on the fixation and penetration of silver during the chalcopyrite leaching using moderate thermophilic microorganisms; Influencia de la temperatura en la fijacion y penetracion de la plata durante la lixiviacion de calcopirita con microorganismos termofilos moderados

Energy Technology Data Exchange (ETDEWEB)

Cancho, L.; Blazquez, M. L.; Munoz, J. A.; Gonzalez, F.; Ballester, A.

2004-07-01

Bio leaching of chalcopyrite using mesophilic microorganisms considerable improves in the presence of silver. However, the studies carried out with moderate thermophilic microorganisms do not show a significant improvement with regard to the use of mesophilic bacteria. The main objective of the present work has been to study the silver fixation on chalcopyrite ar 35 and 45 degree centigree and its influence on the microbiological attack. Different observations using SEM, EDS microanalysis and concentration profiles using electron microprobe have been carried out. The study of the different samples showed that silver fixation was more favourable at 35 degree centigree than at 45 degree centigree. In addition, bacterial action improved silver penetration through attack cracks. (Author)

Influence of temperature on the fixation and penetration of silver during the chalcopyrite leaching using moderate thermophilic microorganisms

International Nuclear Information System (INIS)

Cancho, L.; Blazquez, M. L.; Munoz, J. A.; Gonzalez, F.; Ballester, A.

2004-01-01

Bio leaching of chalcopyrite using mesophilic microorganisms considerable improves in the presence of silver. However, the studies carried out with moderate thermophilic microorganisms do not show a significant improvement with regard to the use of mesophilic bacteria. The main objective of the present work has been to study the silver fixation on chalcopyrite ar 35 and 45 degree centigree and its influence on the microbiological attack. Different observations using SEM, EDS microanalysis and concentration profiles using electron microprobe have been carried out. The study of the different samples showed that silver fixation was more favourable at 35 degree centigree than at 45 degree centigree. In addition, bacterial action improved silver penetration through attack cracks. (Author)

Relative Numbers of Certain Microbial Groups Present in Compost Used for Mushroom (Agaricus bisporus) Propagation

Science.gov (United States)

Fordyce, C.

1970-01-01

The relative numbers of microorganisms associated with compost during mushroom production were studied by the dilution plate method. Thermophilic actinomycetes and fungi were isolated with a very high frequency early in the growing season. Although numbers of thermophilic bacteria diminished slowly during the season, the thermophilic fungi and actinomycetes diminished rapidly with the latter disappearing after 6 weeks. Mesophilic fungi other than Agaricus or Trichoderma remained relatively stable throughout the growing period. Agaricus could be isolated between the first and third break. Trichoderma became dominant after the fourth break. The mesophilic bacterial counts diminished during the most productive portion of the mushroom cropping season and then increased to much higher numbers toward the end of the season. PMID:5529631

New process controls in the co-fermentation of organic waste and municipal sewage sludge; Neue Verfahrensfuehrungen bei der Co-Vergaerung von Bioabfaellen und kommunalen Klaerschlaemmen

Energy Technology Data Exchange (ETDEWEB)

Schaepers, D.; Schierholt, M.; Buer, T.; Risse, H. [Technische Hochschule Aachen (DE). Inst. fuer Siedlungswasserwirtschaft (ISA)

1999-07-01

For the co-fermentation of organic waste and sewage sludge in digester towers at municipal sewage treatment plant, mainly single-stage processes have so far been studied or are in use in part. Within the framework of a project sponsored by the foundation Oswald-Schulze-Stiftung, the use of a two-stage mode of operation (thermophilic/mesophilic) for co-fermenting organic waste and sewage sludge was investigated. By adding organic waste to the digester content, biogas production per reactor volume was more than doubled in comparison with exclusive sewage sludge fermentation. Because of the thermophilic stage for the conditioning of organic waste, specific biogas yield for an organic load of 1.5 kg organic dry residue TR/m{sup 3*}d was slightly enhanced in comparison with single-stage co-fermentation. (orig.) [German] Zur Co-Vergaerung von Bioabfaellen und Klaerschlamm in Faultuermen kommunaler Klaeranlagen werden bislang hauptsaechlich einstufige Verfahren untersucht und teilweise eingesetzt. Im Rahmen eines von der Oswald-Schulze-Stiftung gefoerderten Projektes wurde der Einsatz einer 2-stufigen Betriebsweise (thermophil/mesophil) bei der Co-Vergaerung von Bioabfaellen und Klaerschlamm untersucht. Die Biogasproduktion pro Reaktorvolumen konnte durch die Zugabe von Bioabfall in die Faulbehaelter gegenueber der reinen Klaerschlammfaulung mehr als verdoppelt werden. Durch die thermophile Stufe zur Vorbehandlung der Bioabfaelle konnte die spezifische Biogasausbeute bei einer organischen Raumbelastung von 1,5 kg o TR/m{sup 3*}d gegenueber der 1-stufigen Co-Vergaerung leicht erhoeht werden. (orig.)

Optimizing PHB and Protease Production by Box Behnken Design

Directory of Open Access Journals (Sweden)

Amro Abd al fattah Amara

2013-04-01

Full Text Available Mixed culture is more suitable to adapt more flexible fermentation process and produce different product simultaneously. In this study a mixed Bacillus culture was investigated for their ability to produce the bioplastic "Polyhydroxybutyrate" and both of the mesophilic and the thermophilic proteases in one flask. Box-Behnken experimental design was used. The produced amount of PHB has been increased significantly. Meanwhile there is a competition between PHB and proteases. The maximum produced amount of PHB using Box-Behnken design was 2.82 g/l/48 h with protease activity equal to 41.9 Units/ml/48 h for thermophilic proteases and 99.65 Units/ml/48 h for mesophilic proteases. Excel solver was used for extra-optimization for the optimum conditions obtained from Box-Behnken experiments and its model. The maximum PHB obtained after using Excel solver was 2.88 g/l/48 h. The maximum mesophilic and thermophilic activities obtained at the same PHB production conditions were 175.68 and 243.38 Units/ml respectively. The model accuracy as obtained from Excel solver was 118.8%, which prove the power of the experimental design in optimizing such complicated process. The strategies used in this study are recommended for the production of PHB and different proteases simultaneously using Bacillus mixed culture. ABSTRAK: Kultur campuran adalah lebih sesuai bagi proses penapaian yang fleksibel dan ia boleh menghasilkan produk yang berbeza secara serentak. Dalam kajian ini keupayaan  menghasilkan "Polyhydroxybutyrate" bioplastik serta mesofilik dan termofilik protease dalam satu flask oleh  kultur Bacillus campuran telah disiasat. Eksperimen rekabentuk Box-Behnken telah digunakan. Jumlah PHB yang dikeluarkan meningkat dengan ketara dan terdapat persaingan antara PHB dan protease. Jumlah keluaran PHB maksima menggunakan rekabentuk Box-Behnken adalah 2.82 g/l/48 jam dengan aktiviti protease sama dengan 41.9 Unit/ml/48 jam untuk protease termofilik dan 99.65 Unit

Microbial Contamination of Date Rutab Collected from the Markets of Al-Hofuf City in Saudi Arabia

Directory of Open Access Journals (Sweden)

Siddig H. Hamad

2012-01-01

Full Text Available The microbial contamination of 60 samples from six date cultivars in the rutab stage purchased from different retail outlets in AL-Hofuf City, Saudi Arabia was studied. All samples were found contaminated with aerobic mesophilic bacteria at loads in the order 102 to 105 cfu/cm2 with some significant differences among varieties that can be attributed to differences in the weather conditions during rutab season. Also all samples, except only one, were contaminated with molds and yeasts at loads in the order 102 to 103 cfu/cm2. Potentially pathogenic Staphylococcus aureus was detected in 57 samples and A. flavus/parasiticus in 13 samples, while coliforms were detected in 39 samples.

Ecophysiological behaviour of hardwood species in renaturalization processes of coniferous plantations [Campania

International Nuclear Information System (INIS)

Borghetti, M.; Saracino, A.; D'Alessandro, C.M.

2005-01-01

Coniferous plantations may play a nurse effect for natural regeneration of native hardwood species, which would otherwise be conditioned by intraspecific competition due to trees of the upper layers or be prevented by high radiation load of open environments. Regulation of canopy cover by means of thinning generates temporary or permanent variations of levels of irradiance in lower forest layers. These affect the capability of recruitment and establishment and the ecophysiological behaviour of natural regeneration. Here we present a review of the notions on effects of relative irradiance variations on ecophysiological behaviour of native tree species in lower layers of mesophile and meso-xerophile forests, giving some specific examples produced during the national project PRIN 2003 FOR BIO [it

Fungus-Mediated Preferential Bioleaching of Waste Material Such as Fly - Ash as a Means of Producing Extracellular, Protein Capped, Fluorescent and Water Soluble Silica Nanoparticles

Science.gov (United States)

Khan, Shadab Ali; Uddin, Imran; Moeez, Sana; Ahmad, Absar

2014-01-01

In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Energy dispersive analysis of X-rays (EDAX). PMID:25244567

Degradation of petroleum hydrocarbons in a laboratory aquifer column

International Nuclear Information System (INIS)

Billowits, M.; Whyte, L.; Greer, C.; Ramsay, J.

1998-01-01

One of the primary mechanisms for eliminating hydrocarbon pollutants from the environment is degradation of hydrocarbons by indigenous microorganisms. This report describes a study in which samples from a petroleum polluted shallow aquifer in the Yukon were used which contained a hundred times greater concentration of psychrotropic bacteria than mesophilic bacteria. Results showed a maximum degradation of 47 per cent of the total petroleum hydrocarbon in columns which simulated the aquifer conditions and to which nutrients were added. It was concluded that although in this case bioaugmentation of the columns with a psychrotropic hydrocarbon-degrading consortium increased microbial numbers, total petroleum hydrocarbon degradation was not much greater than could be achieved by remediation with nutrients alone

Fungus-mediated preferential bioleaching of waste material such as fly - ash as a means of producing extracellular, protein capped, fluorescent and water soluble silica nanoparticles.

Directory of Open Access Journals (Sweden)

Shadab Ali Khan

Full Text Available In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL, Transmission electron microscopy (TEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and Energy dispersive analysis of X-rays (EDAX.

Engineering Deinococcus geothermailis for Bioremediation of High-Temperature Radioactive Waste Environments

International Nuclear Information System (INIS)

Brim, Hassan; Venkateswaran, Amudhan; Kostandarithes, Heather M.; Fredrickson, Jim K.; Daly, Michael J.

2003-01-01

Deinococcus geothermalis is an extremely radiation-resistant thermophilic bacterium closely related to the mesophile Deinococcus radiodurans, which is being engineered for in situ bioremediation of radioactive wastes

Serotonin and conditioning: focus on Pavlovian psychostimulant drug conditioning.

Science.gov (United States)

Carey, Robert J; Damianopoulos, Ernest N

2015-04-01

Serotonin containing neurons are located in nuclei deep in the brainstem and send axons throughout the central nervous system from the spinal cord to the cerebral cortex. The vast scope of these connections and interactions enable serotonin and serotonin analogs to have profound effects upon sensory/motor processes. In that conditioning represents a neuroplastic process that leads to new sensory/motor connections, it is apparent that the serotonin system has the potential for a critical role in conditioning. In this article we review the basics of conditioning as well as the serotonergic system and point up the number of non-associative ways in which manipulations of serotonin neurotransmission have an impact upon conditioning. We focus upon psychostimulant drug conditioning and review the contribution of drug stimuli in the use of serotonin drugs to investigate drug conditioning and the important impact drug stimuli can have on conditioning by introducing new sensory stimuli that can create or mask a CS. We also review the ways in which experimental manipulations of serotonin can disrupt conditioned behavioral effects but not the associative processes in conditioning. In addition, we propose the use of the recently developed memory re-consolidation model of conditioning as an approach to assess the possible role of serotonin in associative processes without the complexities of performance effects related to serotonin treatment induced alterations in sensory/motor systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Differential stability of TATA box binding proteins from archaea with different optimal growth temperatures

Science.gov (United States)

Kopitz, Annette; Soppa, Jörg; Krejtschi, Carsten; Hauser, Karin

2009-09-01

The TATA box binding protein (TBP) is involved in promoter recognition, the first step of transcription initiation. TBP is universally conserved and essential in archaea and eukaryotes. In archaea, TBPs have to be stable and to function in species that cover an extremely wide range of optimal growth temperatures (OGTs), from below 0 °C to more than 100 °C. Thus, the archaeal TBP family is ideally suited to study the evolutionary adaptation of proteins to an extremely wide range of temperatures. We characterized the thermostability of one mesophilic and one thermophilic TBP by infrared spectroscopy. Transition temperatures ( Tms) of thermal unfolding have been determined using TBPs from Methanosarcina mazei (OGT 37 °C) and from Methanothermobacter thermautotrophicus (OGT 65 °C). Furthermore, the influence of protein and salt concentration on thermostability has been characterized. Together with previous studies, our results reveal that the Tms of archaeal TBPs are closely correlated with the OGTs of the respective species. Noteworthy, this is also true for the TBP from M. mazei representing the first characterized TBP from a mesophilic archaeon. In contrast, the only characterized eukaryotic TBP of the mesophilic plant Arabidopsis thaliana has a Tm more than 40 °C above the OGT.

Structure and dynamics of the microbial communities underlying the carboxylate platform for biofuel production

Energy Technology Data Exchange (ETDEWEB)

Hollister, Emily B.; Gentry, Terry J. [Texas A and M Univ., College Station, TX (United States). Dept. of Soil and Crop Sciences; Forrest, Andrea K.; Holtzapple, Mark T. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering; Wilkinson, Heather H.; Ebbole, Daniel J. [Texas A and M Univ., College Station, TX (United States). Dept. of Plant Pathology and Microbiology; Malfatti, Stephanie A.; Tringe, Susannah G. [DOE Joint Genome Institute, Walnut Creek, CA (United States)

2010-09-15

The carboxylate platform utilizes a mixed microbial community to convert lignocellulosic biomass into chemicals and fuels. While much of the platform is well understood, little is known about its microbiology. Mesophilic (40 C) and thermophilic (55 C) fermentations employing a sorghum feedstock and marine sediment inoculum were profiled using 16S rRNA tag-pyrosequencing over the course of a 30-day incubation. The contrasting fermentation temperatures converted similar amounts of biomass, but the mesophilic community was significantly more productive, and the two temperatures differed significantly with respect to propionic and butyric acid production. Pyrotag sequencing revealed the presence of dynamic communities that responded rapidly to temperature and changed substantially over time. Both temperatures were dominated by bacteria resembling Clostridia, but they shared few taxa in common. The species-rich mesophilic community harbored a variety of Bacteroidetes, Actinobacteria, and {gamma}-Proteobacteria, whereas the thermophilic community was composed mainly of Clostridia and Bacilli. Despite differences in composition and productivity, similar patterns of functional class dynamics were observed. Over time, organisms resembling known cellulose degraders decreased in abundance, while organisms resembling known xylose degraders increased. Improved understanding of the carboxylate platform's microbiology will help refine platform performance and contribute to our growing knowledge regarding biomass conversion and biofuel production processes. (orig.)

Endotoxin Structures in the Psychrophiles Psychromonas marina and Psychrobacter cryohalolentis Contain Distinctive Acyl Features

Directory of Open Access Journals (Sweden)

Charles R. Sweet

2014-07-01

Full Text Available Lipid A is the essential component of endotoxin (Gram-negative lipopolysaccharide, a potent immunostimulatory compound. As the outer surface of the outer membrane, the details of lipid A structure are crucial not only to bacterial pathogenesis but also to membrane integrity. This work characterizes the structure of lipid A in two psychrophiles, Psychromonas marina and Psychrobacter cryohalolentis, and also two mesophiles to which they are related using MALDI-TOF MS and fatty acid methyl ester (FAME GC-MS. P. marina lipid A is strikingly similar to that of Escherichia coli in organization and total acyl size, but incorporates an unusual doubly unsaturated tetradecadienoyl acyl residue. P. cryohalolentis also shows structural organization similar to a closely related mesophile, Acinetobacter baumannii, however it has generally shorter acyl constituents and shows many acyl variants differing by single methylene (-CH2- units, a characteristic it shares with the one previously reported psychrotolerant lipid A structure. This work is the first detailed structural characterization of lipid A from an obligate psychrophile and the second from a psychrotolerant species. It reveals distinctive structural features of psychrophilic lipid A in comparison to that of related mesophiles which suggest constitutive adaptations to maintain outer membrane fluidity in cold environments.

Structure and dynamics of the microbial communities underlying the carboxylate platform for biofuel production

Energy Technology Data Exchange (ETDEWEB)

Hollister, Emily B; Gentry, Terry J [Texas A and M Univ., College Station, TX (United States). Dept. of Soil and Crop Sciences; Forrest, Andrea K; Holtzapple, Mark T [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering; Wilkinson, Heather H; Ebbole, Daniel J [Texas A and M Univ., College Station, TX (United States). Dept. of Plant Pathology and Microbiology; Malfatti, Stephanie A; Tringe, Susannah G [DOE Joint Genome Institute, Walnut Creek, CA (United States)

2010-09-15

The carboxylate platform utilizes a mixed microbial community to convert lignocellulosic biomass into chemicals and fuels. While much of the platform is well understood, little is known about its microbiology. Mesophilic (40 C) and thermophilic (55 C) fermentations employing a sorghum feedstock and marine sediment inoculum were profiled using 16S rRNA tag-pyrosequencing over the course of a 30-day incubation. The contrasting fermentation temperatures converted similar amounts of biomass, but the mesophilic community was significantly more productive, and the two temperatures differed significantly with respect to propionic and butyric acid production. Pyrotag sequencing revealed the presence of dynamic communities that responded rapidly to temperature and changed substantially over time. Both temperatures were dominated by bacteria resembling Clostridia, but they shared few taxa in common. The species-rich mesophilic community harbored a variety of Bacteroidetes, Actinobacteria, and {gamma}-Proteobacteria, whereas the thermophilic community was composed mainly of Clostridia and Bacilli. Despite differences in composition and productivity, similar patterns of functional class dynamics were observed. Over time, organisms resembling known cellulose degraders decreased in abundance, while organisms resembling known xylose degraders increased. Improved understanding of the carboxylate platform's microbiology will help refine platform performance and contribute to our growing knowledge regarding biomass conversion and biofuel production processes. (orig.)

Cereulide formation by Bacillus weihenstephanensis and mesophilic emetic Bacillus cereus at temperature abuse depends on pre-incubation conditions

DEFF Research Database (Denmark)

Thorsen, Line; Budde, Birgitte Bjørn; Henrichsen, Lars

2009-01-01

at temperature abuse has not been investigated previously. Results of the present study indicate that storage at 5 and 8 °C will not lead to emetic intoxications, however the time at, and choice of chill temperature will determine the amount of cereulide produced in a temperature abuse situation. These results...

Biokinetics and bacterial communities of propionate oxidizing bacteria in phased anaerobic sludge digestion systems.

Science.gov (United States)

Zamanzadeh, Mirzaman; Parker, Wayne J; Verastegui, Yris; Neufeld, Josh D

2013-03-15

Phased anaerobic digestion is a promising technology and may be a potential source of bio-energy production. Anaerobic digesters are widely used for sewage sludge stabilization and thus a better understanding of the microbial process and kinetics may allow increased volatile solids reduction and methane production through robust process operation. In this study, we analyzed the impact of phase separation and operational conditions on the bio-kinetic characteristics and communities of bacteria associated with four phased anaerobic digestion systems. In addition to significant differences between bacterial communities associated with different digester operating temperatures, our results also revealed that bacterial communities in the phased anaerobic digestion systems differed between the 1st and 2nd phase digesters and we identified strong community composition correlations with several measured physicochemical parameters. The maximum specific growth rates of propionate oxidizing bacteria (POB) in the mesophilic and thermophilic 1st phases were 11 and 23.7 mgCOD mgCOD(-1) d(-1), respectively, while those of the mesophilic and thermophilic 2nd-phase digesters were 6.7 and 18.6 mgCOD mgCOD(-1) d(-1), respectively. Hence, the biokinetic characteristics of the POB population were dependent on the digester loading. In addition, we observed that the temperature dependency factor (θ) values were higher for the less heavily loaded digesters as compared to the values obtained for the 1st-phase digesters. Our results suggested the appropriate application of two sets of POB bio-kinetic that reflect the differing growth responses as a function of propionate concentration (and/or organic loading rates). Also, modeling acetogenesis in phased anaerobic sludge digestion systems will be improved considering a population shift in separate phases. On the basis of the bio-kinetic values estimated in various digesters, high levels of propionate in the thermophilic digesters may be

Chromosomal Conditions

Science.gov (United States)

... and more. Stony Point, NY 10980 Close X Home > Complications & Loss > Birth defects & other health conditions > Chromosomal conditions Chromosomal conditions ... Disorders See also: Genetic counseling , Your family health history Last reviewed: February, 2013 ... labor & premature birth The newborn intensive care unit (NICU) Birth defects & ...

Estudo da estabilidade quÍmica e microbiológica do suco de caju in natura armazenado em diferentes condições de estocagem Study of the chemical and microbiological stability of cashew apple juice in different storage conditions

Directory of Open Access Journals (Sweden)

Flávia Conde Lavinas

2006-12-01

. In the juice kept at room temperature, an increase in the count of mesophile bacteria and yeasts and moulds was observed. In the juices stored when refrigerated for seven days, mesophile bacteria counts decreased and yeast and mould counts increased. In the frozen juices, the yeast and mould counts remained lower than the initial counts, while mesophile bacteria showed variation until the thirtieth day and remained stable in less than one logarithmic cycle above the initial count. Throughout the study period, refrigeration and freezing were efficient for ascorbic acid and microbiological quality preservation of the cashew apple juice.

Reconstruction of boundary conditions from internal conditions using viability theory

KAUST Repository

Hofleitner, Aude; Claudel, Christian G.; Bayen, Alexandre M.

2012-01-01

This article presents a method for reconstructing downstream boundary conditions to a HamiltonJacobi partial differential equation for which initial and upstream boundary conditions are prescribed as piecewise affine functions and an internal condition is prescribed as an affine function. Based on viability theory, we reconstruct the downstream boundary condition such that the solution of the Hamilton-Jacobi equation with the prescribed initial and upstream conditions and reconstructed downstream boundary condition satisfies the internal value condition. This work has important applications for estimation in flow networks with unknown capacity reductions. It is applied to urban traffic, to reconstruct signal timings and temporary capacity reductions at intersections, using Lagrangian sensing such as GPS devices onboard vehicles.

Reconstruction of boundary conditions from internal conditions using viability theory

KAUST Repository

Hofleitner, Aude

2012-06-01

This article presents a method for reconstructing downstream boundary conditions to a HamiltonJacobi partial differential equation for which initial and upstream boundary conditions are prescribed as piecewise affine functions and an internal condition is prescribed as an affine function. Based on viability theory, we reconstruct the downstream boundary condition such that the solution of the Hamilton-Jacobi equation with the prescribed initial and upstream conditions and reconstructed downstream boundary condition satisfies the internal value condition. This work has important applications for estimation in flow networks with unknown capacity reductions. It is applied to urban traffic, to reconstruct signal timings and temporary capacity reductions at intersections, using Lagrangian sensing such as GPS devices onboard vehicles.

Betting on conditionals

OpenAIRE

Politzer , Guy; Over , David P; Baratgin , Jean

2010-01-01

A study is reported testing two hypotheses about a close parallel relation between indicative conditionals, if A then B, and conditional bets, I bet you that if A then B. The first is that both the indicative conditional and the conditional bet are related to the conditional probability, P(B|A). The second is that de Finetti's three-valued truth table has psychological reality for both types of conditional – true, false, or void for indicative conditionals and win, lose or void for conditiona...

Bacillus sp. JR3 esterase LipJ: A new mesophilic enzyme showing traces of a thermophilic past.

Directory of Open Access Journals (Sweden)

Judit Ribera

Full Text Available A search for extremophile enzymes from ancient volcanic soils in El Hierro Island (Canary Islands, Spain allowed isolation of a microbial sporulated strain collection from which several enzymatic activities were tested. Isolates were obtained after sample cultivation under several conditions of nutrient contents and temperature. Among the bacterial isolates, supernatants from the strain designated JR3 displayed high esterase activity at temperatures ranging from 30 to 100°C, suggesting the presence of at least a hyper-thermophilic extracellular lipase. Sequence alignment of known thermophilic lipases allowed design of degenerated consensus primers for amplification and cloning of the corresponding lipase, named LipJ. However, the cloned enzyme displayed maximum activity at 30°C and pH 7, showing a different profile from that observed in supernatants of the parental strain. Sequence analysis of the cloned protein showed a pentapeptide motif -GHSMG- distinct from that of thermophilic lipases, and much closer to that of esterases. Nevertheless, the 3D structural model of LipJ displayed the same folding as that of thermophilic lipases, suggesting a common evolutionary origin. A phylogenetic study confirmed this possibility, positioning LipJ as a new member of the thermophilic family of bacterial lipases I.5. However, LipJ clusters in a clade close but separated from that of Geobacillus sp. thermophilic lipases. Comprehensive analysis of the cloned enzyme suggests a common origin of LipJ and other bacterial thermophilic lipases, and highlights the most probable divergent evolutionary pathway followed by LipJ, which during the harsh past times would have probably been a thermophilic enzyme, having lost these properties when the environment changed to more benign conditions.

Bacillus sp. JR3 esterase LipJ: A new mesophilic enzyme showing traces of a thermophilic past.

Science.gov (United States)

Ribera, Judit; Estupiñán, Mónica; Fuentes, Alba; Fillat, Amanda; Martínez, Josefina; Diaz, Pilar

2017-01-01

A search for extremophile enzymes from ancient volcanic soils in El Hierro Island (Canary Islands, Spain) allowed isolation of a microbial sporulated strain collection from which several enzymatic activities were tested. Isolates were obtained after sample cultivation under several conditions of nutrient contents and temperature. Among the bacterial isolates, supernatants from the strain designated JR3 displayed high esterase activity at temperatures ranging from 30 to 100°C, suggesting the presence of at least a hyper-thermophilic extracellular lipase. Sequence alignment of known thermophilic lipases allowed design of degenerated consensus primers for amplification and cloning of the corresponding lipase, named LipJ. However, the cloned enzyme displayed maximum activity at 30°C and pH 7, showing a different profile from that observed in supernatants of the parental strain. Sequence analysis of the cloned protein showed a pentapeptide motif -GHSMG- distinct from that of thermophilic lipases, and much closer to that of esterases. Nevertheless, the 3D structural model of LipJ displayed the same folding as that of thermophilic lipases, suggesting a common evolutionary origin. A phylogenetic study confirmed this possibility, positioning LipJ as a new member of the thermophilic family of bacterial lipases I.5. However, LipJ clusters in a clade close but separated from that of Geobacillus sp. thermophilic lipases. Comprehensive analysis of the cloned enzyme suggests a common origin of LipJ and other bacterial thermophilic lipases, and highlights the most probable divergent evolutionary pathway followed by LipJ, which during the harsh past times would have probably been a thermophilic enzyme, having lost these properties when the environment changed to more benign conditions.

Microwave enhanced digestion of aerobic SBR sludge | Kennedy ...

African Journals Online (AJOL)

MWs) for improving characteristics of aerobic sequencing batch reactor (SBR) sludge to enhance mesophilic anaerobic digestion. Effects of pretreatment temperature, MW irradiation intensity and solids concentration on sludge characterisation ...

Relationship between concentrations of microbiological agents in the air of agricultural settings and occurrence of work-related symptoms in exposed persons

Directory of Open Access Journals (Sweden)

Barbara Mackiewicz

2015-09-01

related symptoms and the concentration of total airborne microorganisms (R=0.748555; P=0.020317, mesophilic bacteria (R=0.7573; P=0.029548, Gram-negative bacteria (R=0.835938; P=0.019129, and endotoxins (R=0.705356; P=0.03378. The correlations between the concentrations of thermophilic actinomycetes and fungi, on one side, and frequency of work-related symptoms on the other, did not attain the threshold of significance (P=0.087049 and P=0.062963, respectively. Results of the meta-analysis confirm harmful health effects of the total airborne microorganisms, total airborne mesophilic bacteria, airborne Gram-negative bacteria, and airborne bacterial endotoxin on the occupationally-exposed agricultural workers, and indicate a need for the establishment of internationally recognized occupational exposure limits for these microbial agents.

[Study on the quantitative and qualitative composition of moulds colonizing sunflower seeds (Helianthus annus L.)].

Science.gov (United States)

Janda, Katarzyna; Wolska, Jolanta; Debia, Kamila

2015-01-01

The aim of study was to estimate the qualitative and quantitative composition of moulds colonizing sunflower seeds on RBCA, YpSs, DG18 media at 25, 37, and 45°C. Twenty samples of sunflower seeds (not roasted and not salted) were used for the analysis. The highest number of moulds were xerophilic species isolated on DG18 at 25°C (33), followed by mesophilic species (29) on RBCA medium at 25°C, and mesophilic (22) and thermophilic species (10) on YpSs medium at 37, and 45°C, respectively. Eurotium herbariorum was isolated from all samples. A total of 287 strains belonging to 52 mould species were isolated from sunflower seeds. The study revealed new species not previously isolated from sunflower seeds mycobiota.

The Negated Conditional: A Litmus Test for the Suppositional Conditional?

Science.gov (United States)

Handley, Simon J.; Evans, Jonathan St. B. T.; Thompson, Valerie A.

2006-01-01

Under the suppositional account of conditionals, when people think about a conditional assertion, "if p then q," they engage in a mental simulation in which they imagine p holds and evaluate the probability that q holds under this supposition. One implication of this account is that belief in a conditional equates to conditional probability…

Classic conditioning in aged rabbits: delay, trace, and long-delay conditioning.

Science.gov (United States)

Solomon, P R; Groccia-Ellison, M E

1996-06-01

Young (0.5 years) and aged (2+, 3+, and 4+ years) rabbits underwent acquisition of the classically conditioned nictitating membrane response in a delay (500-ms conditioned stimulus [CS], 400-ms interstimulus interval [ISI]), long-delay (1,000-ms CS, 900-ms ISI), or trace (500-ms CS, 400-ms stimulus-free period) paradigm. Collapsing across age groups, there is a general tendency for animals to acquire trace conditioning more slowly than delay conditioning. Collapsing across conditioning paradigms, there is a general tendency for aged animals to acquire more slowly than younger animals. Of greater significance, however, are the age differences in the different conditioning paradigms. In the delay and long-delay paradigms, significant conditioning deficits first appeared in the 4(+)-year-old group. In the trace conditioning paradigm, significant conditioning deficits became apparent in the 2(+)-year-old animals.

Production of extracellular lipase by a new strain Staphylococcus ...

African Journals Online (AJOL)

SAM

2014-07-09

Jul 9, 2014 ... mesophilic and solvent tolerant lipase with industrial potential. Key words: ..... amount of enzyme production indicating the inducible nature of the .... biodiesel production, oleochemical industry, polymer syn- thesis and ...

Pseudo-affinity chromatography of rumen microbial cellulase on ...

African Journals Online (AJOL)

Administrator

2011-06-06

Jun 6, 2011 ... was shown that freeze drying and precipitation of enzyme using ammonium sulphate were the best. Based on ... potassium sodium tartrate, di-potassium hydrogen phosphate anhy- ..... Cellulosomes from mesophilic bacteria.

Backbone and side-chain 1H, 15N and 13C resonance assignments of two Sac10b family members Mvo10b and Mth10bTQQA from archaea.

Science.gov (United States)

Xuan, Jinsong; Yao, Hongwei; Feng, Yingang; Wang, Jinfeng

2017-10-01

The Sac10b family proteins, also named as Alba, are small, basic, nucleic acid-binding proteins widely distributed in archaea. They possess divergent physiological functions such as binding to both DNA and RNA with a high affinity and involving in genomic DNA compaction, RNA transactions and transcriptional regulations. The structures of many Sac10b family proteins from hyperthermophilic archaea have been reported, while those from thermophilic and mesophilic archaea are largely unknown. As was pointed out, the homologous members from thermophilic and mesophilic archaea may have functions different from the hyperthermophilic members. Therefore, comparison of these homologous members can provide biophysical and structural insight into the functional diversity and thermal adaptation mechanism. The present work mainly focused on the NMR study of two Sac10b family members, Mvo10b and Mth10b, from the mesophilic and thermophilic archaea, respectively. To overcome the difficulties caused by the oligomerization and conformation heterogeneity of Mth10b, a M13T/L17Q/I20Q/P56A mutant Mth10b (Mth10bTQQA) was constructed and used together with Mvo10b for multi-dimensional NMR experiments. The resonance assignments of Mvo10b and Mth10bTQQA are reported for further structural determination which is a basis for understanding the functional diversity and their thermal adaption mechanisms.

454 pyrosequencing analyses of bacterial and archaeal richness in 21 full-scale biogas digesters.

Science.gov (United States)

Sundberg, Carina; Al-Soud, Waleed A; Larsson, Madeleine; Alm, Erik; Yekta, Sepehr S; Svensson, Bo H; Sørensen, Søren J; Karlsson, Anna

2013-09-01

The microbial community of 21 full-scale biogas reactors was examined using 454 pyrosequencing of 16S rRNA gene sequences. These reactors included seven (six mesophilic and one thermophilic) digesting sewage sludge (SS) and 14 (ten mesophilic and four thermophilic) codigesting (CD) various combinations of wastes from slaughterhouses, restaurants, households, etc. The pyrosequencing generated more than 160,000 sequences representing 11 phyla, 23 classes, and 95 genera of Bacteria and Archaea. The bacterial community was always both more abundant and more diverse than the archaeal community. At the phylum level, the foremost populations in the SS reactors included Actinobacteria, Proteobacteria, Chloroflexi, Spirochetes, and Euryarchaeota, while Firmicutes was the most prevalent in the CD reactors. The main bacterial class in all reactors was Clostridia. Acetoclastic methanogens were detected in the SS, but not in the CD reactors. Their absence suggests that methane formation from acetate takes place mainly via syntrophic acetate oxidation in the CD reactors. A principal component analysis of the communities at genus level revealed three clusters: SS reactors, mesophilic CD reactors (including one thermophilic CD and one SS), and thermophilic CD reactors. Thus, the microbial composition was mainly governed by the substrate differences and the process temperature. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Persistence of pathogenic prion protein during simulated wastewater treatment processes

Science.gov (United States)

Hinckley, G.T.; Johnson, C.J.; Jacobson, K.H.; Bartholomay, C.; Mcmahon, K.D.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.

2008-01-01

Transmissible spongiform encephalopathies (TSEs, prion diseases) are a class of fatal neurodegenerative diseases affecting a variety of mammalian species including humans. A misfolded form of the prion protein (PrP TSE) is the major, if not sole, component of the infectious agent. Prions are highly resistant to degradation and to many disinfection procedures suggesting that, if prions enter wastewater treatment systems through sewers and/or septic systems (e.g., from slaughterhouses, necropsy laboratories, rural meat processors, private game dressing) or through leachate from landfills that have received TSE-contaminated material, prions could survive conventional wastewater treatment Here, we report the results of experiments examining the partitioning and persistence of PrPTSE during simulated wastewater treatment processes including activated and mesophilic anaerobic sludge digestion. Incubation with activated sludge did not result in significant PrPTSE degradation. PrPTSE and prion infectivity partitioned strongly to activated sludge solids and are expected to enter biosolids treatment processes. A large fraction of PrPTSE survived simulated mesophilic anaerobic sludge digestion. The small reduction in recoverable PrPTSE after 20-d anaerobic sludge digestion appeared attributable to a combination of declining extractability with time and microbial degradation. Our results suggest that if prions were to enter municipal wastewater treatment systems, most would partition to activated sludge solids, survive mesophilic anaerobic digestion, and be present in treated biosolids. ?? 2008 American Chemical Society.

Sensory quality of Camembert-type cheese: Relationship between starter cultures and ripening molds.

Science.gov (United States)

Galli, Bruno Domingues; Martin, José Guilherme Prado; da Silva, Paula Porrelli Moreira; Porto, Ernani; Spoto, Marta Helena Fillet

2016-10-03

Starter cultures and ripening molds used in the manufacture of moldy cheese aimed at obtaining characteristic flavors and textures considerably differ among dairy industries. Thus, the study of variables inherent to the process and their influence on sensory patterns in cheese can improve the standardization and control of the production process. The aim of this work was to study the influence of three different variables on the sensory quality of Camembert-type cheese: type of lactic bacteria, type of ripener molds and inoculation method. Batches of Camembert-type cheese were produced using O or DL-type mesophilic starter culture, ripened with Penicillium camemberti or Penicillium candidum and mold inoculation was made directly into the milk or by spraying. All batches were sensorially evaluated using Quantitative Descriptive Analysis (QDA) with panelists trained for various attributes. Among the combinations analyzed, those resulting in more typical Camembert-type cheese were those using O-type mesophilic starter culture and P. candidum maturation mold directly applied into the milk or sprayed and those using DL-type mesophilic starter and P. camemberti ripener mold applied by surface spraying. These results demonstrate, therefore, that the combination of different ripener molds, inoculation methods and starter cultures directly influences the sensory quality of Camembert-type cheese, modifying significantly its texture, appearance, aroma and taste. Copyright © 2016 Elsevier B.V. All rights reserved.

Combined effect of γ-irradiation and bacterial-fermented dextrose on microbiological quality of refrigerated pork sausages

Science.gov (United States)

Dussault, D.; Benoit, C.; Lacroix, M.

2012-08-01

The objective of this study was to evaluate the effect of a concentrated fermented dextrose (FD), a natural antimicrobial product, combined with low dose γ-irradiation (1.5 kGy) on the microbiological quality of fresh pork sausages. Fresh pork sausages containing the FD (0.25%, 0.5% and 0.75%) were prepared in a meat pilot plant and were irradiated using a UC-15A irradiator equipped with a 60Cobalt source. The γ-irradiation treatment alone was able to reduce the initial psychrophilic and mesophilic bacteria by more than 2 log CFU/g and kept the lactobacillus population under the detection limit (100 CFU/g). Results also showed that the FD alone was able to extend the shelf life of the sausages from 5 days up to 13 days. At day 13, the FD or irradiation alone showed 2 log CFU/g less mesophilic bacteria than the control. After combining FD and irradiation another reduction of the microbial count of 1 log CFU/g was observed. When combining the irradiation treatment with the FD results it showed a reduced growth rate of the psychrophilic and mesophilic bacteria compared to both treatments alone. This study demonstrated that FD with low dose gamma irradiation act in synergy to reduce the multiplication of the total bacterial flora in fresh sausages.

The Microbiologic Quality of the Air in Broiler Houses

Directory of Open Access Journals (Sweden)

Silvana Popescu

2010-10-01

Full Text Available The aim of this paper was to assess the microbiologic quality of air in broiler houses. The number of bacteria (mesophile, staphylococci, streptococci and gram-negatives and fungi was determined in 6 broiler houses with chicken of different ages (1-6 weeks old through specific methods. The results were statistically processed by using the SPSS software, version 17. The number of bacteria and fungi varied in the 6 broiler houses, ranging from 2.25 x 105 to 2.17 x 106 for the total number of mesophilic bacteria, between 3.5 x 104 – 1.27 x 106 for staphylococci, 7.4 x 104 – 5.01 x 105 for streptococci, 3.5 x 103 – 1.53 x 104 for gram-negatives and from 1.67 x 104 to 8.13 x 104 for fungi, respectively. The number of bacteria and fungi were significantly lower for the younger chicken (p < 0.05. The proportions of groups with hygienic significance within the total mesophilic bacteria number were: 15.7% - 68.6% staphylococci, 6.7% - 45.6% streptococci and 0.2% - 4.5% gram-negatives. The comparative appraisal of the microbiologic quality in the broiler houses showed better air quality in the youngest chicken’s house (one week of age. The obtained results indicate the necessity for increased ventilation and for air disinfection during the chicken’s fattening period.

CHARACTERIZATION OF AUTOCHTHONUS LACTIC FLORA OF A CAMPANIAN CHILLI CHEESE PRODUCED FROM RAW SHEEP MILK

Directory of Open Access Journals (Sweden)

A. Mormile

2012-08-01

Full Text Available The natural lactic flora of the artisanal chilli “Tramonti” cheese, a typical product manufactured in the “Lattari mountains”, area of Salerno province (Italy, was investigated. Particular attention was paid to the growth dynamics assessment and to the molecular identification of the indigenous lactic acid bacteria involved in the ripening of this cheese made with raw sheep milk without starter cultures. One batch was monitored taking 4 sample on 0, 30, 50 and 105 ripening days. Lactobacillus and Lactococcus were enumerated and randomly isolated on MRS and LM17 agar (32ºC x 48h -mesophilic flora- and 42°C x 48h -thermophilic flora, respectively. N. 66 presumptive lactic acid bacteria isolates, gram positive and catalase negative, were genotipically identified by Ribotyping. Mesophilic Lactobacillus remained at levels of 107 cfu/g during whole maturation time and thermophilic Lactobacillus, from initial values of 105 cfu/g, reached concentratios of 106 cfu/g at the end of maturation. Mesophilic and thermophilic Lactococcus showed, on average, levels of 106 since the beginning of the ripening. Ribotyping allowed to detect 4 lactic acid bacteria species: Enterococcus faecium (65,15%, Lactococcus lactis spp. cremoris (24,24%, Enterococcus faecalis (6,06% and Enterococcus durans (4,54%, showing the diversity of indigenous lactic acid bacteria of chilli “Tramonti” cheese.

The Feasibility of Thermophilic Caldimonas manganoxidans as a Platform for Efficient PHB Production.

Science.gov (United States)

Hsiao, Li-Jung; Lin, Ji-Hong; Sankatumvong, Pantitra; Wu, Tzong-Ming; Li, Si-Yu

2016-11-01

Recently, poly(3-hydroxybutyrate) (PHB) has been found in a few thermophilic strains where several advantages can be gained from running fermentation at high temperatures. Caldimonas manganoxidans, a thermophilic gram-negative bacterium, was investigated for the feasibility as a PHB-producing strain. It is suggested that the best fermentation strategy for achieving the highest PHB concentration of 5.4 ± 1.1 g/L (from 20 g/L glucose) in 24 h is to use the fermentation conditions that are favored for the bacterial growth, yet temperature and pH should be chosen at conditions that are favored for the PHB content. Besides, the above fermentation conditions produce PHB that has a high molecular weight of 1274 kDa with a low polydispersity index (PDI) of 1.45, where the highest Mw of PHB of 1399 kDa (PDI of 1.32) is obtained in this study. To the best knowledge of authors, C. manganoxidans has the best PHB productivity among the thermophiles and is comparable to those common PHB-producing mesophiles.

ANAEROBIC DIGESTION OF WASTEWATER WITH HIGH SULFATE CONCENTRATION USING MICRO-AERATION AND NATURAL ZEOLITES

Directory of Open Access Journals (Sweden)

S. Montalvo

Full Text Available Abstract The behavior of anaerobic digestion in batch and UASB reactors using a microaerobic process and natural zeolites was studied. Laboratory assays were carried out across 4 sets of variables: different COD/SO42- ratios, different airflow levels, with and without natural zeolites and room and mesophilic controlled temperatures. The microaerobic process demonstrated hydrogen sulfide removal levels exceeding 90% in most cases, while maintaining the flammable condition of the generated biogas. The level of COD removal exceeded 75% in UASB reactors despite their operation under very low hydraulic retention times (2.8-4.8 hours. The effectiveness of natural zeolites in accelerating UASB reactor startup was demonstrated. Results showing the positive influence of zeolites on the granulation process in UASB reactors were also achieved.

1342-IJBCS-Article-Ifeoma Mbeayi Nwooha

African Journals Online (AJOL)

KODJIO NORBERT

solids, copper, iron, alkalinity, appearance, taste, colour, aerobic mesophilic count, coliform counts were evaluated. ... water supply schemes are being adapted to ... Therefore an adequate supply of ... to the flourishing demand for such street.

Hydrophobic environment is a key factor for the stability of thermophilic proteins.

Science.gov (United States)

Gromiha, M Michael; Pathak, Manish C; Saraboji, Kadhirvel; Ortlund, Eric A; Gaucher, Eric A

2013-04-01

The stability of thermophilic proteins has been viewed from different perspectives and there is yet no unified principle to understand this stability. It would be valuable to reveal the most important interactions for designing thermostable proteins for such applications as industrial protein engineering. In this work, we have systematically analyzed the importance of various interactions by computing different parameters such as surrounding hydrophobicity, inter-residue interactions, ion-pairs and hydrogen bonds. The importance of each interaction has been determined by its predicted relative contribution in thermophiles versus the same contribution in mesophilic homologues based on a dataset of 373 protein families. We predict that hydrophobic environment is the major factor for the stability of thermophilic proteins and found that 80% of thermophilic proteins analyzed showed higher hydrophobicity than their mesophilic counterparts. Ion pairs, hydrogen bonds, and interaction energy are also important and favored in 68%, 50%, and 62% of thermophilic proteins, respectively. Interestingly, thermophilic proteins with decreased hydrophobic environments display a greater number of hydrogen bonds and/or ion pairs. The systematic elimination of mesophilic proteins based on surrounding hydrophobicity, interaction energy, and ion pairs/hydrogen bonds, led to correctly identifying 95% of the thermophilic proteins in our analyses. Our analysis was also applied to another, more refined set of 102 thermophilic-mesophilic pairs, which again identified hydrophobicity as a dominant property in 71% of the thermophilic proteins. Further, the notion of surrounding hydrophobicity, which characterizes the hydrophobic behavior of residues in a protein environment, has been applied to the three-dimensional structures of elongation factor-Tu proteins and we found that the thermophilic proteins are enriched with a hydrophobic environment. The results obtained in this work highlight the

MICROBIOLOGICAL EVOLUTION OF DACIA SAUSAGE, A DRY CURED ROMANIAN SAUSAGE

Directory of Open Access Journals (Sweden)

Ana Maria Simion Ciuciu

2011-09-01

Full Text Available Selected starter cultures were used to produce the traditional Romanian dry cured sausage, Dacia. A control sausage was produced without starter culture (sausage A, one with L. sakei CECT 5964 and S. equorum SA25 (sausage B and one with L. sakei CECT 5964, S. equorum SA25 and L. acidophilus CECT 903 (sausage C. Samples from each batch of sausages were taken at 0 (mix before stuffing, and after 2, 4, 7, 14, 21 and 28 days of ripening. Counts of total aerobic mesophilic flora, lactic acid bacteria, salt tolerant flora, and Enterobacteriaceae and some physical-chemical parameters (moisture, NaCl, pH and aw values were determined. High microbial counts (log CFU were observed with values at the end of ripening period: for lactic acid bacteria 9.77 (A, 11.47 (B and 11.19 (C; for total aerobic mesophilic flora 9.89 (A, 11.38 (B and 11.30 (C; for salt tolerant flora 4.45 (A, 5.31 (B and 5.27 (C. The starter cultures had a significant inhibitory effect on Enterobacteriaceae counts (log CFU, values at the end of ripening period being 1.32 (A, 0.33 (B and not detected (C. A significant decrease in the pH values is observed until the seventh day of ripening, showing a slight, but progressive increase after the 14th day of ripening. Results show that the production and ripening process in a pilot scale chamber under controlled conditions contributes in obtaining safe and homogeneous products.

Can anaerobic digestion of sugar beet pulp support the circular economy? a study of biogas and nutrient potential

Science.gov (United States)

Suhartini, S.; Heaven, S.; Banks, C. J.

2018-03-01

Anaerobic digestion (AD), known as a biological process without oxygen to convert complex organic materials into biogas, is capable of processing large tonnage quantities of biomass, such as sugar beet pulp (SBP). In addition to biogas production, its use allows nutrients and organic carbon recycle back to agriculture through the spreading of digestate. Digestate still contains high amount of nutrients (N, P, K) for use as biofertiliser. The aims of this research were to determine biogas/methane potential as a baseline for comparison with performance in semi-continuous digestion, and to determine nutrient and potentially toxic elements (PTE) of digestate fractions with respect to their potential for utilisation in agriculture. The Biochemical Methane Potential (BMP) test was performed in triplicate against blank and positive controls over a period of 28 days with gas measured at regular intervals. Semi-continuous AD of SBP was operated under mesophilic and thermophilic condition for 206 and 165 days. The results indicated that SBP is a very promising feedstock for AD, with the average BMP of 0.321 l CH4 g-1 VS and biogas potential of 0.605 l g-1 VS. Under semi-continuous operation, SBP also demonstrated positive results. Digestates from mesophilic and thermophilic AD of SBP contained useful quantities of N, P and K, with an acceptable Ni concentration in accordance to limits for PTE. These results suggest that digestate has the potential to be utilised on agricultural and arable land. This study illustrated the positive effects of applying AD to the achievement of economic savings and environmental-friendly performance.

Conditional uncertainty principle

Science.gov (United States)

Gour, Gilad; Grudka, Andrzej; Horodecki, Michał; Kłobus, Waldemar; Łodyga, Justyna; Narasimhachar, Varun

2018-04-01

We develop a general operational framework that formalizes the concept of conditional uncertainty in a measure-independent fashion. Our formalism is built upon a mathematical relation which we call conditional majorization. We define conditional majorization and, for the case of classical memory, we provide its thorough characterization in terms of monotones, i.e., functions that preserve the partial order under conditional majorization. We demonstrate the application of this framework by deriving two types of memory-assisted uncertainty relations, (1) a monotone-based conditional uncertainty relation and (2) a universal measure-independent conditional uncertainty relation, both of which set a lower bound on the minimal uncertainty that Bob has about Alice's pair of incompatible measurements, conditioned on arbitrary measurement that Bob makes on his own system. We next compare the obtained relations with their existing entropic counterparts and find that they are at least independent.

Application of Carnobacterium maltaromaticum as a feed additive for weaned rabbits to improve meat microbial quality and safety.

Science.gov (United States)

Koné, Amenan Prisca; Zea, Juliana Maria Velez; Gagné, Dominic; Cinq-Mars, Dany; Guay, Frédéric; Saucier, Linda

2018-01-01

This study addresses the improvement of meat microbial quality by enriching the diet of farm animals with a protective culture. Weaned Grimaud rabbits were divided into two experimental groups: a control and a diet supplemented with Micocin® (Carnobacterium maltaromaticum CB1; 8Log 10 CFU/kg of feed). Overall, meat quality was not affected substantially by the treatment. Total Aerobic Mesophilic (TAM), Escherichia coli and other coliforms, Enterobacteriaceae, Staphylococcus aureus, Pseudomonas spp., Listeria spp. and presumptive lactic acid bacteria counts were evaluated on whole thighs stored under aerobic (0, 3, 6, 8days) and anaerobic (0, 5, 10, 15, 20days) conditions at 4°C. The results demonstrated that the microflora on refrigerated thighs was modulated by the addition of Micocin® (Pmeat stored under anaerobic conditions at 4°C with a 2 Log difference at the end of a 15-day storage (P=0.025). Copyright © 2017 Elsevier Ltd. All rights reserved.

Reactor performance and microbial community dynamics during anaerobic co-digestion of municipal wastewater sludge with restaurant grease waste at steady state and overloading stages.

Science.gov (United States)

Razaviarani, Vahid; Buchanan, Ian D

2014-11-01

Linkage between reactor performance and microbial community dynamics was investigated during mesophilic anaerobic co-digestion of restaurant grease waste (GTW) with municipal wastewater sludge (MWS) using 10L completely mixed reactors and a 20day SRT. Test reactors received a mixture of GTW and MWS while control reactors received only MWS. Addition of GTW to the test reactors enhanced the biogas production and methane yield by up to 65% and 120%, respectively. Pyrosequencing revealed that Methanosaeta and Methanomicrobium were the dominant acetoclastic and hydrogenotrophic methanogen genera, respectively, during stable reactor operation. The number of Methanosarcina and Methanomicrobium sequences increased and that of Methanosaeta declined when the proportion of GTW in the feed was increased to cause an overload condition. Under this overload condition, the pH, alkalinity and methane production decreased and VFA concentrations increased dramatically. Candidatus cloacamonas, affiliated within phylum Spirochaetes, were the dominant bacterial genus at all reactor loadings. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bayesian prediction of bacterial growth temperature range based on genome sequences

DEFF Research Database (Denmark)

Jensen, Dan Børge; Vesth, Tammi Camilla; Hallin, Peter Fischer

2012-01-01

Background: The preferred habitat of a given bacterium can provide a hint of which types of enzymes of potential industrial interest it might produce. These might include enzymes that are stable and active at very high or very low temperatures. Being able to accurately predict this based...... on a genomic sequence, would thus allow for an efficient and targeted search for production organisms, reducing the need for culturing experiments. Results: This study found a total of 40 protein families useful for distinction between three thermophilicity classes (thermophiles, mesophiles and psychrophiles...... that protein families associated with specific thermophilicity classes can provide effective input data for thermophilicity prediction, and that the naive Bayesian approach is effective for such a task. The program created for this study is able to efficiently distinguish between thermophilic, mesophilic...

Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

DEFF Research Database (Denmark)

ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

1994-01-01

sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...... C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... P60, were isolated and characterized as Desulfotomaculum kuznetsovii. The temperature response of growth and respiration of strain P60 agreed well with the measured sulfate reduction at 50 degrees-70 degrees C. Bacteria similar to strain P60 could thus be responsible for the measured thermophilic...

Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

DEFF Research Database (Denmark)

ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

1994-01-01

C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...... P60, were isolated and characterized as Desulfotomaculum kuznetsovii. The temperature response of growth and respiration of strain P60 agreed well with the measured sulfate reduction at 50 degrees-70 degrees C. Bacteria similar to strain P60 could thus be responsible for the measured thermophilic...

Studies on the bactericidal effect of ionizing radiation on pig manure

Energy Technology Data Exchange (ETDEWEB)

Kleiner, U; Trenner, P [Ministerium fuer Land-, Forst- und Nahrungsgueterwirtschaft der DDR, Eberswalde. Inst. fuer Angewandte Tierhygiene

1983-03-01

Pig manure was treated with electrons and gamma rays at radiation doses of 4, 8, 15 and 30 kGy, resp. The mesophile bacteria were significantly reduced by all electron doses, but with repropagation at the 7. post-irradiation day. Gamma radiation at 4 and 8 kGy resulted also in not lasting reduction of mesophile bacteria. 15 kGy caused a significant and persistent elimination of the germs. 15 kGy electron irradiation and 8 kGy gamma irradiation killed the proteolytic bacteria. Euterococci and lactose-splitting bacteria were killed at 4 kGy irradiation of both kinds. Lasting elimination of manure specific germs was reached with 15 kGy ..gamma..-rays and more than 30 kGy electrons, resp. All the treatments are expensive and cannot be recommended.

Skin Condition Finder

Science.gov (United States)

... SKIN CONDITIONS HEALTH TOPICS FOR PROFESSIONALS Rash and Skin Condition Finder 1 Select Age Group Infant Child ... Toe Toe Webspace Toe Nail CLOSE About the Skin Condition Finder Have a health question or concern? ...

Biodigestion of cassava peels blended with pig dung for methane ...

African Journals Online (AJOL)

OKOROIGWE

2013-10-02

Oct 2, 2013 ... Biogas production from cassava (Manihot esculentus) peels and pig dung under a mesophilic ... is a gap to be filled up by further investigation. Ezekoye ..... Biofertilizer and Chemical Fertilizer Application on Maize Production.

Fixed or adapted conditioning intensity for repeated conditioned pain modulation.

Science.gov (United States)

Hoegh, M; Petersen, K K; Graven-Nielsen, T

2017-12-29

Aims Conditioned pain modulation (CPM) is used to assess descending pain modulation through a test stimulation (TS) and a conditioning stimulation (CS). Due to potential carry-over effects, sequential CPM paradigms might alter the intensity of the CS, which potentially can alter the CPM-effect. This study aimed to investigate the difference between a fixed and adaptive CS intensity on CPM-effect. Methods On the dominant leg of 20 healthy subjects the cuff pressure detection threshold (PDT) was recorded as TS and the pain tolerance threshold (PTT) was assessed on the non-dominant leg for estimating the CS. The difference in PDT before and during CS defined the CPM-effect. The CPM-effect was assessed four times using a CS with intensities of 70% of baseline PTT (fixed) or 70% of PTT measured throughout the session (adaptive). Pain intensity of the conditioning stimulus was assessed on a numeric rating scale (NRS). Data were analyzed with repeated-measures ANOVA. Results No difference was found comparing the four PDTs assessed before CSs for the fixed and the adaptive paradigms. The CS pressure intensity for the adaptive paradigm was increasing during the four repeated assessments (P CPM-effect was higher using the fixed condition compared with the adaptive condition (P CPM paradigms using a fixed conditioning stimulus produced an increased CPM-effect compared with adaptive and increasing conditioning intensities.

Optimisation Study on the Production of Anaerobic Digestate ...

African Journals Online (AJOL)

DR. AMIN

optimise the production of ADC from organic fractions of domestic wastes and the effects of ADC amendments on soil .... (22%), cooked meat (9%), lettuce (11%), carrots. (3%), potato (44%) ... seed was obtained from a mesophilic anaerobic.

Lipid A structural modifications in extreme conditions and identification of unique modifying enzymes to define the Toll-like receptor 4 structure-activity relationship.

Science.gov (United States)

Scott, Alison J; Oyler, Benjamin L; Goodlett, David R; Ernst, Robert K

2017-11-01

Strategies utilizing Toll-like receptor 4 (TLR4) agonists for treatment of cancer, infectious diseases, and other targets report promising results. Potent TLR4 antagonists are also gaining attention as therapeutic leads. Though some principles for TLR4 modulation by lipid A have been described, a thorough understanding of the structure-activity relationship (SAR) is lacking. Only through a complete definition of lipid A-TLR4 SAR is it possible to predict TLR4 signaling effects of discrete lipid A structures, rendering them more pharmacologically relevant. A limited 'toolbox' of lipid A-modifying enzymes has been defined and is largely composed of enzymes from mesophile human and zoonotic pathogens. Expansion of this 'toolbox' will result from extending the search into lipid A biosynthesis and modification by bacteria living at the extremes. Here, we review the fundamentals of lipid A structure, advances in lipid A uses in TLR4 modulation, and the search for novel lipid A-modifying systems in extremophile bacteria. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop. Copyright © 2017 Elsevier B.V. All rights reserved.

Taxonomy and functional roles of biogas microbiota binned from multiple metagenomes of anaerobic digestion systems

DEFF Research Database (Denmark)

Angelidaki, Irini; Treu, Laura; Campanaro, Stefano

Anaerobic digestion, a biologically mediated process, is a worldwide spread technology for biogas production. This work represents the first comprehensive catalogue of microbial genomes populating mesophilic and thermophilic biogas reactors treating manure, agro-industrial organic residues. High ...

Microbiology and physiology of anaerobic fermentations of cellulose. Progress report, September 1, 1979-May 15, 1980

Energy Technology Data Exchange (ETDEWEB)

Peck, H.D. Jr.; Ljungdahl, L.G.

1980-01-01

Reseach progress is reported for the period September, 1979 to May, 1980. Studies on the mesophilic and thermophilic microorganisms fermenting cellulose to various products (ethanol, acetate, CO/sub 2/, H/sub 2/, and methane) are summarized. (ACR)

Relationship between Air Pollution and Weather Conditions under Complicated Geographical conditions

Science.gov (United States)

Cheng, Q.; Jiang, P.; Li, M.

2017-12-01

Air pollution is one of the most serious issues all over the world, especially in megacities with constrained geographical conditions for air pollution diffusion. However, the dynamic mechanism of air pollution diffusion under complicated geographical conditions is still be confused. Researches to explore relationship between air pollution and weather conditions from the perspective of local atmospheric circulations can contribute more to solve such problem. We selected three megacities (Beijing, Shanghai and Guangzhou) under different geographical condition (mountain-plain transition region, coastal alluvial plain and coastal hilly terrain) to explore the relationship between air pollution and weather conditions. RDA (Redundancy analysis) model was used to analyze how the local atmospheric circulation acts on the air pollutant diffusion. The results show that there was a positive correlation between the concentration of air pollutants and air pressure, while temperature, precipitation and wind speed have negative correlations with the concentration of air pollutants. Furthermore, geographical conditions, such as topographic relief, have significant effects on the direction, path and intensity of local atmospheric circulation. As a consequence, air pollutants diffusion modes in different cities under various geographical conditions are diverse from each other.

Impact of relative humidity, inoculum carrier and size, and native microbiota on Salmonella ser. Typhimurium survival in baby lettuce.

Science.gov (United States)

López-Gálvez, Francisco; Gil, Maria Isabel; Allende, Ana

2018-04-01

The effects of relative humidity (RH), fluctuating climate conditions, inoculum size and carrier on the survival of Salmonella enterica serovar Typhimurium on baby lettuce in environmental test chambers were studied. Buffered peptone water (BPW), distilled water (DW), and irrigation water (IW) were compared as inoculum carriers. Additionally, survival of Salmonella in suspensions prepared using filtered and unfiltered IW was assessed. Salmonella Typhimurium survived better on baby lettuce plants at high RH independently of the inoculum size. When lettuce plants were grown under fluctuating environmental conditions, Salmonella survival was similar under both RH conditions. Regarding the inoculum carrier, the inoculated microorganism survived better on lettuce plants when BPW was used as carrier both at high and low RH. Survival rate of Salmonella in IW was affected by the presence of native microbiota. Native microbiota present in IW did not affect survival of Salmonella or the levels of mesophilic bacteria on the baby lettuce leaves. The information obtained in the present study contributes to the knowledge on the effect of environmental conditions on pathogenic bacteria survival on growing edible plants. These results are useful when selecting the methodology to carry out experimental studies on the survival of microbial pathogens under different pre-harvest conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

The antimicrobial effects of chopped garlic in ground beef and raw meatball (ciğ köfte).

Science.gov (United States)

Aydin, Ali; Bostan, Kamil; Erkan, Mehmet Emin; Bingöl, Bariş

2007-03-01

This study was carried out to investigate the antimicrobial effects of chopped garlic in ground beef and raw meatball (çig köfte), which is a traditional food product eaten raw. Fresh minced ground beef and raw meatball batter prepared with traditional methods were separated into groups. Chopped and crushed garlic was added to each batch in order to reach various concentrations from 0% to 10%. The ground beef samples were stored at refrigerator and ambient temperatures. The raw meatball samples were only stored at room temperature. All samples were analyzed in order to determine the microbial counts at the 2(nd), 6(th), 12(th), and 24(th) hours of storage. Garlic addition decreased the microbial growth in some ground beef samples kept either at room temperature or in the refrigerator. However, microbial growth increased in some ground beef samples kept in similar conditions. The difference was found in samples kept in the refrigerator for 24 hours in terms of total aerobic mesophilic bacteria and coliform bacteria when garlic used at 10%. The effects of garlic on the microbial growth of both coliforms and Staphylococcus/Micrococcus in the samples kept at room temperature were increased. The yeast and mold counts in ground beef samples kept in any condition were not affected by garlic addition. However, the addition of garlic to the raw meatball mix decreased the microbial count, in terms of total aerobic mesophilic bacteria and yeast and mold counts, when the garlic was added at 5% or 10% (P meatball caused a permanent decrease in yeast and mold count, unlike in ground beef. The results of this study indicate that the chopped garlic has a slowing-down effect on microbiological growth in ground meat depending on the garlic concentration, but this effect was not at an expected level even at the highest concentration, because potential antimicrobial agents in chopped garlic were probably insufficiently extracted.

Microbiological variation amongst fresh and minimally processed vegetables from retail establishers - a public health study in Pakistan

Directory of Open Access Journals (Sweden)

Sair, A.T.

2017-07-01

Full Text Available Fresh and minimally processed ready to eat vegetables are very attractive eatables amongst consumers as convenient, healthy and readily available foods, especially in the South Asian states. They provide numerous nutrients, phytochemicals, and vitamins but also harbor extensive quantity of potentially pathogenic bacteria. The aim of this study was to determine microbiological variation amongst fresh vegetables that were commercially available to the public at numerous retail establishments in Pakistan in order to present an overview of the quality of fresh produce. A total of 133 samples, collected from local distributors and retailers were tested for aerobic mesophilic and psychrotrophic, coliform and yeast and mould counts. Standard plating techniques were used to analyze all samples. Mesophilic count ranged from 3.1 to 10.3 log CFU/g with lowest and highest counts observed in onions and fresh cut vegetables. Psychrotrophic microorganisms count was as high as mesophilic microorganisms. Maximum counts for coliform were found in fresh cut vegetables with 100% samples falling over 6 log CFU/g. These results were consistent with yeast and moulds as well. In our study, Escherichia coli was determined as an indicator organism for 133 samples of fresh and minimally processed vegetables. Fresh cut vegetables showed the highest incidence of presumptive E. coli (69.9%. The results showed a poor quality of fresh vegetables in Pakistan and point to the implementation of good hygiene practices and food safety awareness amongst local distributors, food handlers at retail establishments.

Chemically pretreating slaughterhouse solid waste to increase the efficiency of anaerobic digestion.

Science.gov (United States)

Flores-Juarez, Cyntia R; Rodríguez-García, Adrián; Cárdenas-Mijangos, Jesús; Montoya-Herrera, Leticia; Godinez Mora-Tovar, Luis A; Bustos-Bustos, Erika; Rodríguez-Valadez, Francisco; Manríquez-Rocha, Juan

2014-10-01

The combined effect of temperature and pretreatment of the substrate on the anaerobic treatment of the organic fraction of slaughterhouse solid waste was studied. The goal of the study was to evaluate the effect of pretreating the waste on the efficiency of anaerobic digestion. The effect was analyzed at two temperature ranges (the psychrophilic and the mesophilic ranges), in order to evaluate the effect of temperature on the performance of the anaerobic digestion process for this residue. The experiments were performed in 6 L batch reactors for 30 days. Two temperature ranges were studied: the psychrophilic range (at room temperature, 18°C average) and the mesophilic range (at 37°C). The waste was pretreated with NaOH before the anaerobic treatment. The result of pretreating with NaOH was a 194% increase in the soluble chemical oxygen demand (COD) with a dose of 0.6 g NaOH per g of volatile suspended solids (VSS). In addition, the soluble chemical oxygen demand/total chemical oxygen demand ratio (sCOD/tCOD) increased from 0.31 to 0.7. For the anaerobic treatment, better results were observed in the mesophilic range, achieving 70.7%, 47% and 47.2% removal efficiencies for tCOD, total solids (TS), and volatile solids (VS), respectively. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Airborne Microorganisms in Tie-stall Dairy Barns from Brasov County

Directory of Open Access Journals (Sweden)

Silvana Popescu

2011-05-01

Full Text Available The aim of this study was the assessment of the airborne microorganisms in tie-stall dairy cattle barns, through determination of the total number of bacteria (mesophilic bacteria, staphylococci, streptococci and gram-negative bacteria and fungi. We investigated 8 dairy cattle barns with tie-stalls in Brasov County during the winter of 2009. The mean numbers of bacteria and fungi in the morning and in the evening were: 1.02 °— 105 - 1.26 °— 105 CFU/m3 for mesophilic bacteria, 5.34 °— 104 - 5.91 °— 104 CFU/m3 for staphylococci, 2.93 °— 104 - 3.60 °— 104 CFU/m3 for streptococci, 2.17 °— 103 - 3.48 °— 103 CFU/m3 for gram-negative bacteria and 1.54 °— 104 - 2.75 °— 104 CFU/m3 for fungi. In the investigated cattle houses staphylococci represented 52.35 – 46.90%, streptococci were 28.73 – 28.57%, and the gram-negative bacteria were 2.13 – 2.76% within the overall number of mesophilic bacteria. The numbers of bacteria and fungi were slightly elevated in the evening comparative to the morning, but the differences were statistically insignificant (p>0.05. The great numbers of bacteria and fungi in the air of dairy cattle tie-stall barns indicate an elevated risk of disease for animals and human workers.

A microbiota da carcaça e da carne ovina tratada com ácido acético, embalada a vácuo e maturada por 48 dias Microbial status of the lamb carcass and the meat treated with acetic acid, vacuum packaged and aging for 48 days

Directory of Open Access Journals (Sweden)

Elayne C. de Vasconcelos

2002-12-01

Full Text Available Foi avaliada a carga de bactérias mesófilas e coliformes totais e fecais na superfície da carcaça ovina após 12 horas do abate. Posteriormente, a carne foi cortada em fatias de aproximadamente 3cm de espessura, imersas por um minuto em ácido acético 1% ou em água, embaladas individualmente a vácuo e armazenadas a 1°C. Nos dias 3,13, 23, 33 e 48 de maturação as carnes foram analisadas para bactérias mesófilas e psicrotróficas, mofos e leveduras, coliformes totais e fecais, salmonela e clostrídios sulfito-redutores. As contagens de bactérias mesófilas e psicrotróficas foram menores (pThe load of mesophylic, fecal and total coliform microorganisms on lamb carcass was assessed after 12 hours of slaughtering. Meat was then cut into 3 steaks about 3cm thick. Steaks were dipped for 1 min in either 1% acetic acid solution or plain water, packaged in nylon-polyethylene bags and vacuum-sealed before storing at 1°C. On days 3, 13, 23, 33 and 48 of aging meats were analyzed for mesophilic and psycrotrophic bacteria, moulds and yeasts, total and fecal coliform bacteria, Salmonella and sulfite-reducing Clostridia. Mesophilic and psycrophilic bacterial counts were lower (p<0.05 in meats treated with acetic acid than in the untreated meats on days 13 and 23 and on days 3 and 13, respectively. Mould and yeast counts were lower (p<0.05 in meats treated with acetic acid as compared with those untreated only on days 3 and 13 of aging. On day 3 of aging treated meats were lower (p<0.05 in both total and fecal coliform counts than untreated meats. Meat samples were found positive for Salmonella with 3, 13 and 23 days of aging and negative with 33 and 48 days of aging. Sulfite-reducing bacteria were absent in meat samples all through the experimental period. It can be concluded that dipping lamb meat pieces in 1% acetic acid and the aging conditions used in this study can keep low counts of mesophilic, psycrotrophic, and coliform bacteria, as well

A robust nitrifying community in a bioreactor at 50°C opens up the path for thermophilic nitrogen removal

NARCIS (Netherlands)

Courtens, E.N.P.; Spieck, E.; Vilchez-Vargas, R.; Bodé, S.; Boeckx, P.; Schouten, S.; Jáuregui, R.; Pieper, D.H.; Vlaeminck, S.E.; Boon, N.

2016-01-01

The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes

Appréciation et amélioration de la qualité bactériologique du poisson commercialisé au Burundi. Cas de Stolothrissa tanganicae et Luciolates stappersii

Directory of Open Access Journals (Sweden)

Sindayigaya, E.

1990-01-01

Full Text Available Appreciation and improvement of the bacteriological quality of fish commercialized in Burundi. Cases of Stolothrissa tanganicae and Luciolates stappersii. The bacteriological quality of Stolothrissa tanganicae and Luciolates stappersii has been estimated by determining the aerobic mesophilic flora, Staphylococcus aureus as pathogenic bacteria, Escherichia coli and Streptococcus faecalis as fecal contamination indices. The freshness has been evaluated by the determination of the total volatile bases (T.V.B.. At the arrival of fresh fish on the market, the aerobic mesophilic flora was sometimes high due to inadequate handling and processing on board. Escherichia coli, Streptococcus faecalis and Staphylococcus aureus can be found in fresh fish. The determination of the T.V.B. and the bacteriological analysis provided concordant informations. An improvement of bacteriological quality has been obtained by a combination of the traditional conservation methods : drying, salting and smoking.

Spore prevalence and toxigenicity of Bacillus cereus and Bacillus thuringiensis isolates from U.S. retail spices.

Science.gov (United States)

Hariram, Upasana; Labbé, Ronald

2015-03-01

Recent incidents of foodborne illness associated with spices as the vehicle of transmission prompted this examination of U.S. retail spices with regard to Bacillus cereus. This study focused on the levels of aerobic-mesophilic spore-forming bacteria and B cereus spores associated with 247 retail spices purchased from five states in the United States. Samples contained a wide range of aerobic-mesophilic bacterial spore counts (spices had high levels of aerobic spores (> 10(7) CFU/g). Using a novel chromogenic agar, B. cereus and B. thuringiensis spores were isolated from 77 (31%) and 11 (4%) samples, respectively. Levels of B. cereus were spice isolates to form spores, produce diarrheal toxins, and grow at moderately abusive temperatures makes retail spices an important potential vehicle for foodborne illness caused by B. cereus strains, in particular those that produce diarrheal toxins.

[Bioregeneration of the solutions obtained during the leaching of nonferrous metals from waste slag by acidophilic microorganisms].

Science.gov (United States)

Fomchenko, N V; Murav'ev, M I; Kondrat'eva, T F

2014-01-01

The bioregeneration of the solutions obtained after the leaching of copper and zinc from waste slag by sulfuric solutions of ferric sulfate is examined. For bioregeneration, associations of mesophilic and moderately thermqophilic acidophilic chemolithotrophic microorganisms were made. It has been shown that the complete oxidation of iron ions in solutions obtained after the leaching of nonferrous metals from waste slag is possible at a dilution of the pregnant solution with a nutrient medium. It has been found that the maximal rate of oxidation of iron ions is observed at the use of a mesophilic association of microorganisms at a threefold dilution of the pregnant solution with a nutrient medium. The application ofbioregeneration during the production of nonferrous metals from both waste and converter slags would make it possible to approach the technology of their processing using the closed cycle of workflows.

Morganella psychrotolerans sp. nov., a histamine-producing bacterium isolated from various seafoods

DEFF Research Database (Denmark)

Emborg, Jette; Dalgaard, Paw; Ahrens, Peter

2006-01-01

Morganella morganii subsp. morganii (strain LMG 7874T) and Morganella morganii subsp. sibonii (strain DSM 14850T), respectively. Analysis of the 16S rRNA gene sequences showed a similarity of 98.6 % between mesophilic and psychrotolerant isolates. However, fragments of seven protein-encoding housekeeping...... genes (atpD, dnaN, gyrB, hdc, infB, rpoB and tuf) all showed less than 90.9 % sequence similarity between the two groups. The psychrotolerant isolates grew at 0-2 {degrees}C and also differed from the mesophilic M. morganii isolates with respect to growth at 37 {degrees}C and in 8.5 % (w/v) Na......Cl and fermentation of D-galactose. The psychrotolerant strains appear to represent a novel species, for which the name Morganella psychrotolerans sp. nov. is proposed. The type strain is U2/3T (=LMG 23374T=DSM 17886T)....

Strategies for the anaerobic digestion of the organic fraction of municipal solid waste: an overview

DEFF Research Database (Denmark)

Hartmann, H.; Ahring, Birgitte Kiær

2006-01-01

Different process strategies for anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) are reviewed weighing high-solids versus low-solids, mesophilic versus thermophilic and single-stage versus multi-stage processes. The influence of different waste characteristics...... such as composition of biodegradable fractions, C:N ratio and particle size is described. Generally, source sorting of OFMSW and a high content of food waste leads to higher biogas yields than the use of mechanically sorted OFMSW. Thermophilic processes are more efficient than mesophilic processes in terms of higher...... biogas yields at different organic loading rates (OLR). Highest biogas yields are achieved by means of wet thermophilic processes at OLRs lower than 6 kg-VS(.)m(-3) d(-1). High-solids processes appear to be relatively more efficient when OLRs higher than 6 kg-VS(.)m(-3) d(-1) are applied. Multi...

Characterizing a thermostable Cas9 for bacterial genome editing and silencing

NARCIS (Netherlands)

Mougiakos, Ioannis; Mohanraju, Prarthana; Bosma, Elleke F.; Vrouwe, Valentijn; Finger Bou, Max; Naduthodi, Mihris I.S.; Gussak, Alex; Brinkman, Rudolf B.L.; Kranenburg, Van Richard; Oost, Van Der John

2017-01-01

CRISPR-Cas9-based genome engineering tools have revolutionized fundamental research and biotechnological exploitation of both eukaryotes and prokaryotes. However, the mesophilic nature of the established Cas9 systems does not allow for applications that require enhanced stability, including

Stabilization of enzymes against thermal stress and freeze-drying by mannosylglycerate

NARCIS (Netherlands)

Ramos, A.; Raven, N.; Sharp, R.J.; Bartolucci, S.; Rossi, M.; Cannio, R.; Lebbink, J.; Oost, van der J.; Vos, de W.M.; Santos, H.

1997-01-01

2-O-(beta)-Mannosylglycerate, a solute that accumulates in some (hyper)thermophilic organisms, was purified from Pyrococcus furiosus cells, and its effect on enzyme stabilization in vitro was assessed. Enzymes from hyperthermophilic, thermophilic, and mesophilic sources were examined. The

Characterizing a thermostable Cas9 for bacterial genome editing and silencing

DEFF Research Database (Denmark)

Mougiakos, Ioannis; Mohanraju, Prarthana; Bosma, Elleke Fenna

2017-01-01

CRISPR-Cas9-based genome engineering tools have revolutionized fundamental research and biotechnological exploitation of both eukaryotes and prokaryotes. However, the mesophilic nature of the established Cas9 systems does not allow for applications that require enhanced stability, including...

Complete genome sequence of the photoautotrophic and bacteriochlorophyll e-synthesizing green sulfur bacterium Chlorobaculum limnaeum DSM 1677T

DEFF Research Database (Denmark)

Tank, Marcus; Liu, Zhenfeng; Frigaard, Niels-Ulrik

2017-01-01

Chlorobaculum limnaeum DSM 1677T is a mesophilic, brown-colored, chlorophototrophic green sulfur bacterium that produces bacteriochlorophyll e and the carotenoid isorenieratene as major pigments. This bacterium serves as a model organism in molecular research on photosynthesis, sulfur metabolism...

Different cultivation methods to acclimatise ammonia-tolerant methanogenic consortia

DEFF Research Database (Denmark)

Tian, Hailin; Fotidis, Ioannis; Mancini, Enrico

2017-01-01

reactors (i.e. batch, fed-batch and continuous stirred-tank reactors (CSTR)) operated at mesophilic (37°C) and thermophilic (55°C) conditions were assessed, based on methane production efficiency, incubation time, TAN/FAN (total ammonium nitrogen/free ammonia nitrogen) levels and maximum methanogenic...... activity. Overall, fed-batch cultivation was clearly the most efficient method compared to batch and CSTR. Specifically, by saving incubation time up to 150%, fed-batch reactors were acclimatised to nearly 2-fold higher FAN levels with a 37%-153% methanogenic activity improvement, compared to batch method....... Meanwhile, CSTR reactors were inhibited at lower ammonia levels. Finally, specific methanogenic activity test showed that hydrogenotrophic methanogens were more active than aceticlastic methanogens in all FAN levels above 540 mg NH3-N L-1....

Immobilization of CotA, an extremophilic laccase from Bacillus subtilis, on glassy carbon electrodes for biofuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Beneyton, T.; El Harrak, A.; Griffiths, A.D.; Taly, V. [Institut de Science et d' Ingenierie Supramoleculaire, CNRS UMR, Strasbourg (France); Hellwig, P. [Institut de Chimie, Universite de Strasbourg, CNRS UMR, Strasbourg (France)

2011-01-15

Thanks to their high stability over a wide range of experimental conditions, extremophilic enzymes represent an interesting alternative to mesophilic enzymes as catalysts for biofuel cell applications. In the present work, we report for the first time the immobilization of a thermophilic laccase (CotA from Bacillus subtilis endospore coat) on glassy carbon electrodes functionalized via electrochemical reduction of in situ generated aminophenyl monodiazonium salts. We compare the performance of CotA-modified electrodes for the reduction of O{sub 2} to mutant variants and demonstrate that the measured electrical current is directly correlated to the catalytic efficiencies (k{sub cat}/K{sub m}) of the immobilized enzyme. CotA-modified electrodes showed an optimal operation temperature of 45-50 C and stable catalytic activity for at least 7 weeks. (author)

Optimization of biogas production from olive-oil mill wastewater, by codigesting with diluted poultry-manure

International Nuclear Information System (INIS)

Gelegenis, John; Georgakakis, Dimitris; Angelidaki, Irini; Christopoulou, Nicholetta; Goumenaki, Maria

2007-01-01

Optimization of biogas production from olive-mill wastewater (OMW) was attempted by codigesting with diluted poultry-manure (DPM) at mesophilic conditions. A series of laboratory experiments were performed in continuously-operating reactors, fed with mixtures of OMW and DPM at various concentrations. It was concluded that codigestion of OMW with DPM is possible without any dilution of OMW or addition of any chemicals. Biogas production was slightly higher when OMW was added to DPM up to a critical concentration (about 40%, expressed as contribution of OMW to the volatile solids of the mixture), after which production is decreased. The results were further verified by scaling up to a continuously-operating pilot-plant reactor digesting DPM, and confirmed that no negative impact was imposed by adding OMW up to the above critical value

Ancient photosynthetic eukaryote biofilms in an Atacama Desert coastal cave

Science.gov (United States)

Azua-Bustos, A.; Gonzalez-Silva, C.; Mancilla, R.A.; Salas, L.; Palma, R.E.; Wynne, J.J.; McKay, C.P.; Vicuna, R.

2009-01-01

Caves offer a stable and protected environment from harsh and changing outside prevailing conditions. Hence, they represent an interesting habitat for studying life in extreme environments. Here, we report the presence of a member of the ancient eukaryote red algae Cyanidium group in a coastal cave of the hyperarid Atacama Desert. This microorganism was found to form a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic "cave" Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described in this work may represent an evolutionary island for life in the midst of the Atacama Desert. ?? Springer Science + Business Media, LLC 2009.

Miscellaneous conditions

International Nuclear Information System (INIS)

Berquist, T.H.; Hoffman, A.D.

1989-01-01

This paper reports on numerous conditions (systemic diseases, metabolic diseases, etc.) that may also affect the foot and ankle. In many cases, imaging of the foot and ankle is not performed for primary diagnostic purposes. However, radiographic changes do occur with these conditions. Therefore, it is important to be aware of radiographic abnormalities that these diseases may cause in the foot and ankle

Multidimensional HAM-conditions

DEFF Research Database (Denmark)

Hansen, Ernst Jan de Place

Heat, Air and Moisture (HAM) conditions, experimental data are needed. Tests were performed in the large climate simulator at SBi involving full-scale wall elements. The elements were exposed for steady-state conditions, and temperature cycles simulating April and September climate in Denmark....... The effect on the moisture and temperature conditions of the addition of a vapour barrier and an outer cladding on timber frame walls was studied. The report contains comprehensive appendices documenting the full-scale tests. The tests were performed as a part of the project 'Model for Multidimensional Heat......, Air and Moisture Conditions in Building Envelope Components' carried out as a co-project between DTU Byg and SBi....

ADP-dependent Phosphofructokinases in Mesophilic and Thermophilic Methanogenic Archaea

NARCIS (Netherlands)

Verhees, C.H.; Tuininga, J.E.; Kengen, S.W.M.; Stams, A.J.M.; Oost, van der J.; Vos, de W.M.

2001-01-01

Phosphofructokinase (PFK) is a key enzyme of the glycolytic pathway in all domains of life. Two related PFKs, ATP-dependent and PPi-dependent PFK, have been distinguished in bacteria and eucarya, as well as in some archaea. Hyperthermophilic archaea of the order Thermococcales, including Pyrococcus

Detecting bacterial spores in soup manufacturing

NARCIS (Netherlands)

van Zuijlen, A.C.M.; Oomes, S.J.C.M.; Vos, P.; Brul, S.

2009-01-01

Spores from mesophilic aerobic sporeforming bacteria (Bacillus) are sometimes able to survive the thermal process of commercial sterile products and sporadically cause spoilage or food poisoning. Because of an increasing demand for more fresh products, ideally the processing temperatures should be

Thermozymes and their applications

NARCIS (Netherlands)

Bruins, M.E.; Janssen, A.E.M.; Boom, R.M.

2001-01-01

Enzymes from thermophilic microorganisms, thermozymes, have unique characteristics such as temperature, chemical, and pH stability. They can be used in several industrial processes, in which they replace mesophilic enzymes or chemicals. Thermozymes are often used when the enzymatic process is

Establishment of markerless gene deletion tools in thermophilic Bacillus smithii and construction of multiple mutant strains

NARCIS (Netherlands)

Bosma, E.F.; Weijer, van de A.H.P.; Vlist, L.; Vos, de W.M.; Oost, van der J.; Kranenburg, van R.

2015-01-01

BACKGROUND: Microbial conversion of biomass to fuels or chemicals is an attractive alternative for fossil-based fuels and chemicals. Thermophilic microorganisms have several operational advantages as a production host over mesophilic organisms, such as low cooling costs, reduced contamination risks

Genome sequences of two Leuconostoc pseudomesenteroides strains isolated from Danish dairy starter cultures

DEFF Research Database (Denmark)

Pedersen, Thomas Bæk; Kot, Witold Piotr; Hansen, L.H.

2014-01-01

The lactic acid bacterium Leuconostoc pseudomesenteroides can be found in mesophilic cheese starters, where it produces aromatic compounds from, e.g., citrate. Here, we present the draft genome sequences of two L. pseudomesenteroides strains isolated from traditional Danish cheese starters....

Synonymous codon usage in different protein secondary structural ...

Indian Academy of Sciences (India)

PRAKASH KUMAR

2007-06-21

Jun 21, 2007 ... in the DSSP file, beta-sheets by E and B and coils by the rest. 3. Results ...... Authors are thankful to the Department of Biotechnology,. New Delhi for ... thermophilic Aquifex aeolicus and mesophilic Bacillus subtilis;. J. Biomol.

Treatability and kinetics studies of mesophilic aerobic biodegradation of high oil and grease pet food wastewater

International Nuclear Information System (INIS)

Liu, Victor Lei; Nakhla, G.; Bassi, A.

2004-01-01

In this work, batch activated sludge studies were investigated for the treatment of raw pet food wastewater characterized by oil and grease concentrations of 50,000-66,000 mg/L, COD and BOD concentrations of 100,000 and 80,000 mg/L, respectively, as well as effluent from an existing anaerobic digester treating the aforementioned wastewater. A pre-treatment process, dissolved air flotation (DAF) achieved 97-99% reduction in O and G to about 400-800 mg/L, which is still atypically high for AS. The batch studies were conducted using a 4-L bioreactor at room temperature (21 deg. C) under different conditions. The experimental results showed for the DAF pretreated effluent, 92% COD removal efficiency can be achieved by using conventional activated sludge system at a 5 days contact time and applied initial soluble COD to biomass ratio of 1.17 mg COD/mg VSS. Similarly for the digester effluent at average oil and grease concentrations of 13,500 mg/L, activated sludge affected 63.7-76.2% soluble COD removal at 5 days. The results also showed that all kinetic data best conformed to the zero order biodegradation model with a low biomass specific maximum substrate utilization rate of 0.168 mg COD/mg VSS day reflecting the slow biodegradability of the wastewater even after 99% removal of oil and grease

Linkages between mineralogy, fluid chemistry, and microbial communities within hydrothermal chimneys from the Endeavour Segment, Juan de Fuca Ridge

Science.gov (United States)

Lin, T. J.; Ver Eecke, H. C.; Breves, E. A.; Dyar, M. D.; Jamieson, J. W.; Hannington, M. D.; Dahle, H.; Bishop, J. L.; Lane, M. D.; Butterfield, D. A.; Kelley, D. S.; Lilley, M. D.; Baross, J. A.; Holden, J. F.

2016-02-01

Rock and fluid samples were collected from three hydrothermal chimneys at the Endeavour Segment, Juan de Fuca Ridge to evaluate linkages among mineralogy, fluid chemistry, and microbial community composition within the chimneys. Mössbauer, midinfrared thermal emission, and visible-near infrared spectroscopies were utilized for the first time to characterize vent mineralogy, in addition to thin-section petrography, X-ray diffraction, and elemental analyses. A 282°C venting chimney from the Bastille edifice was composed primarily of sulfide minerals such as chalcopyrite, marcasite, and sphalerite. In contrast, samples from a 300°C venting chimney from the Dante edifice and a 321°C venting chimney from the Hot Harold edifice contained a high abundance of the sulfate mineral anhydrite. Geochemical modeling of mixed vent fluids suggested the oxic-anoxic transition zone was above 100°C at all three vents, and that the thermodynamic energy available for autotrophic microbial redox reactions favored aerobic sulfide and methane oxidation. As predicted, microbes within the Dante and Hot Harold chimneys were most closely related to mesophilic and thermophilic aerobes of the Betaproteobacteria and Gammaproteobacteria and sulfide-oxidizing autotrophic Epsilonproteobacteria. However, most of the microbes within the Bastille chimney were most closely related to mesophilic and thermophilic anaerobes of the Deltaproteobacteria, especially sulfate reducers, and anaerobic hyperthermophilic archaea. The predominance of anaerobes in the Bastille chimney indicated that other environmental factors promote anoxic conditions. Possibilities include the maturity or fluid flow characteristics of the chimney, abiotic Fe2+ and S2- oxidation in the vent fluids, or O2 depletion by aerobic respiration on the chimney outer wall.

Study of the combined effect of spices and marination on beef meat vacuum packaged

Directory of Open Access Journals (Sweden)

DANIELA ISTRATI

2011-12-01

Full Text Available Fresh beef slices were marinated by immersion in marinades based on dry red wine, lime-tree honey, salt, spices and seasoning plants as thyme (Thymus vulgaris, marjoram (Majorana hortensis, garlic (Allium sativum and horseradish (Armoracia rusticana. Control samples were represented by raw meat without marination treatment but stored in the same conditions as marinated samples. After marination, meat pieces were packed under vacuum and stored at refrigeration temperature of 4°C for 12 days. The influence of the combined effect of spices and marination on beef stability was evaluated by monitoring pH evolution, degree of lipid oxidation and by microbiological analysis. For control samples, a mean increase of 0.47 log CFU/g of total mesophilic aerobic bacteria was observed during the 48 h of storage, but for the samples marinated with the addition of spices was observed a decrease of 0.57 log CFU/g. The growth of LAB in control samples was generally limited and did not exceed 5 log CFU/g. During storage at 4°C, marination with the addition in the base marinade (wine, honey, garlic, pepper and salt of thyme, marjoram and horseradish separately inhibited the growth of LAB while marination with the addition in the base marinade of thyme, marjoram and horseradish together resulted in significantly lower levels of LAB. All marination treatments resulted in significantly lower TBA and POV values at the end of storage compared to the control. Marination with dry red wine, lime-tree honey, thyme marjoram, garlic, and horseradish can evidently control total mesophilic aerobic bacteria, lactic acid bacteria and oxidation of beef meat.

Risky consumption habits and safety of fluid milk available in retail sales outlets in Viçosa, Minas Gerais State, Brazil.

Science.gov (United States)

Pieri, Fabio Alessandro; Colombo, Monique; Merhi, Carolina Milner; Juliati, Vinícius Augusto; Ferreira, Marcello Sebe; Nero, Marcelo Antônio; Nero, Luis Augusto

2014-06-01

This study aimed to assess raw milk consumption habits in the urban population of Viçosa, Minas Gerais, Brazil, and the microbiological safety and quality of the fluid milk available in retail sales outlets in the same region. A simplified questionnaire regarding raw milk consumption was applied to the persons responsible for food acquisition in 411 residences. The regular consumption of raw milk was observed by 18.5% of the interviewers, and lack of knowledge of possible risks related to this food product. Microbiological safety and quality were assessed for raw (n=69), pasteurized (n=80), and ultra-high-temperature (UHT)-treated milk (n=80) by analyzing the counts of mesophilic aerobes, coliforms, and Escherichia coli, and detection of Listeria monocytogenes and Salmonella spp.; raw milk samples were also subjected to enumeration of coagulase-positive Staphylococcus. Concerning raw milk, 59.4% of the samples were considered as produced in inadequate hygienic conditions, 5.8% of the samples presented counts of coagulase-positive Staphylococcus lower than 100 colony-forming units (CFU)/mL, and no samples presented with positive results for L. monocytogenes or Salmonella spp. All pasteurized and UHT milk samples presented with low counts of mesophilic aerobes and coliforms, while L. monocytogenes and Salmonella spp. were absent. The data demonstrated that raw milk was consumed by the population studied. Despite the absence of potential hazards, raw milk was of poor hygienic quality, in contrast with the processed fluid milk available in retail sales outlets that was safe and of good hygienic quality, highlighting the suitability of pasteurized and UHT milk for human consumption.

Application and microbial ecology of psychrotrophs in domestic wastewater treatment at low temperature.

Science.gov (United States)

Xu, Zhenzhen; Ben, Yue; Chen, Zhonglin; Jiang, Anxi; Shen, Jimin; Han, Xiaoyun

2018-01-01

The feasibility of a bunch of screened psychrotrophs being applied to low-temperature wastewater treatment was investigated. The screened psychrophillic strains are capable of growth at a broad temperature-range from 0 to 40 °C and exhibit a preferable TTC-dehydrogenase activity at low temperature (4-10 °C). Along the sharply fluctuant temperatures (25-4-25 °C), the screened psychrotrophs (compared with the indigenous mesophiles) demonstrate less fluctuations of COD removal and more rapid recovery after temperature shocks. COD removal of approximate 80% was recorded by single psychrotrophs (while only 10% by single mesophiles) at low temperature (4 °C). Soft polyurethane foam showed better performance for psychrotrophs immobilization, with the optimal filling rate of 30% (v/v) in the bioreactor. The observation shows that the immobilized psychrotrophs demonstrated a relatively high performance on both conventional and emerging organic contaminants removals at low temperature. In order to check the feasibility of the screened psychrotrophs in treating actual domestic wastewater, a pilot-scale ICABR bioreactor was operated firstly at low temperature (4 °C) and then at seasonal varying temperatures (0-30 °C) for one year, the influent COD of 150-600 mg L -1 was efficiently reduced to 40 ± 18 mg L -1 under the conditions of an overall hydraulic retention time of 10 h. Furthermore, psychrotrophs performed stably as the predominant bacteria family during the whole operation. This study provides evidence that microbial intensification with psychrotrophs was a feasible strategy to improve the efficiency of conventional wastewater treatment process at low temperature. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantitative effects of composting state variables on C/N ratio through GA-aided multivariate analysis.

Science.gov (United States)

Sun, Wei; Huang, Guo H; Zeng, Guangming; Qin, Xiaosheng; Yu, Hui

2011-03-01

It is widely known that variation of the C/N ratio is dependent on many state variables during composting processes. This study attempted to develop a genetic algorithm aided stepwise cluster analysis (GASCA) method to describe the nonlinear relationships between the selected state variables and the C/N ratio in food waste composting. The experimental data from six bench-scale composting reactors were used to demonstrate the applicability of GASCA. Within the GASCA framework, GA searched optimal sets of both specified state variables and SCA's internal parameters; SCA established statistical nonlinear relationships between state variables and the C/N ratio; to avoid unnecessary and time-consuming calculation, a proxy table was introduced to save around 70% computational efforts. The obtained GASCA cluster trees had smaller sizes and higher prediction accuracy than the conventional SCA trees. Based on the optimal GASCA tree, the effects of the GA-selected state variables on the C/N ratio were ranged in a descending order as: NH₄+-N concentration>Moisture content>Ash Content>Mean Temperature>Mesophilic bacteria biomass. Such a rank implied that the variation of ammonium nitrogen concentration, the associated temperature and the moisture conditions, the total loss of both organic matters and available mineral constituents, and the mesophilic bacteria activity, were critical factors affecting the C/N ratio during the investigated food waste composting. This first application of GASCA to composting modelling indicated that more direct search algorithms could be coupled with SCA or other multivariate analysis methods to analyze complicated relationships during composting and many other environmental processes. Copyright © 2010 Elsevier B.V. All rights reserved.

Advanced anaerobic bioconversion of lignocellulosic waste for bioregenerative life support following thermal water treatment and biodegradation by Fibrobacter succinogenes.

Science.gov (United States)

Lissens, Geert; Verstraete, Willy; Albrecht, Tobias; Brunner, Gerd; Creuly, Catherine; Seon, Jerome; Dussap, Gilles; Lasseur, Christophe

2004-06-01

The feasibility of nearly-complete conversion of lignocellulosic waste (70% food crops, 20% faecal matter and 10% green algae) into biogas was investigated in the context of a life support project. The treatment comprised a series of processes, i.e., a mesophilic laboratory scale CSTR (continuously stirred tank reactor), an upflow biofilm reactor, a fiber liquefaction reactor employing the rumen bacterium Fibrobacter succinogenes and a hydrothermolysis system in near-critical water. By the one-stage CSTR, a biogas yield of 75% with a specific biogas production of 0.37 l biogas g(-1) VSS (volatile suspended solids) added at a RT (hydraulic retention time) of 20-25 d was obtained. Biogas yields could not be increased considerably at higher RT, indicating the depletion of readily available substrate after 25 d. The solids present in the CSTR-effluent were subsequently treated in two ways. Hydrothermal treatment (T approximately 310-350 degrees C, p approximately 240 bar) resulted in effective carbon liquefaction (50-60% without and 83% with carbon dioxide saturation) and complete sanitation of the residue. Application of the cellulolytic Fibrobacter succinogenes converted remaining cellulose contained in the CSTR-effluent into acetate and propionate mainly. Subsequent anaerobic digestion of the hydrothermolysis and the Fibrobacter hydrolysates allowed conversion of 48-60% and 30%, respectively. Thus, the total process yielded biogas corresponding with conversions up to 90% of the original organic matter. It appears that particularly mesophilic digestion in conjunction with hydrothermolysis at near-critical conditions offers interesting features for (nearly) complete and hygienic carbon and energy recovery from human waste in a bioregenerative life support context.

Energetics Conditioning Facility

Data.gov (United States)

Federal Laboratory Consortium — The Energetics Conditioning Facility is used for long term and short term aging studies of energetic materials. The facility has 10 conditioning chambers of which 2...

A comparative study of ribosomal proteins: linkage between amino acid distribution and ribosomal assembly

International Nuclear Information System (INIS)

Lott, Brittany Burton; Wang, Yongmei; Nakazato, Takuya

2013-01-01

Assembly of the ribosome from its protein and RNA constituents must occur quickly and efficiently in order to synthesize the proteins necessary for all cellular activity. Since the early 1960’s, certain characteristics of possible assembly pathways have been elucidated, yet the mechanisms that govern the precise recognition events remain unclear. We utilize a comparative analysis to investigate the amino acid composition of ribosomal proteins (r-proteins) with respect to their role in the assembly process. We compared small subunit (30S) r-protein sequences to those of other housekeeping proteins from 560 bacterial species and searched for correlations between r-protein amino acid content and factors such as assembly binding order, environmental growth temperature, protein size, and contact with ribosomal RNA (rRNA) in the 30S complex. We find r-proteins have a significantly high percent of positive residues, which are highly represented at rRNA contact sites. An inverse correlation between the percent of positive residues and r-protein size was identified and is mainly due to the content of Lysine residues, rather than Arginine. Nearly all r-proteins carry a net positive charge, but no statistical correlation between the net charge and the binding order was detected. Thermophilic (high-temperature) r-proteins contain increased Arginine, Isoleucine, and Tyrosine, and decreased Serine and Threonine compared to mesophilic (lower-temperature), reflecting a known distinction between thermophiles and mesophiles, possibly to account for protein thermostability. However, this difference in amino acid content does not extend to rRNA contact sites, as the proportions of thermophilic and mesophilic contact residues are not significantly different. Given the significantly higher level of positively charged residues in r-proteins and at contact sites, we conclude that ribosome assembly relies heavily on an electrostatic component of interaction. However, the binding order of

Conditional Poisson models: a flexible alternative to conditional logistic case cross-over analysis.

Science.gov (United States)

Armstrong, Ben G; Gasparrini, Antonio; Tobias, Aurelio

2014-11-24

The time stratified case cross-over approach is a popular alternative to conventional time series regression for analysing associations between time series of environmental exposures (air pollution, weather) and counts of health outcomes. These are almost always analyzed using conditional logistic regression on data expanded to case-control (case crossover) format, but this has some limitations. In particular adjusting for overdispersion and auto-correlation in the counts is not possible. It has been established that a Poisson model for counts with stratum indicators gives identical estimates to those from conditional logistic regression and does not have these limitations, but it is little used, probably because of the overheads in estimating many stratum parameters. The conditional Poisson model avoids estimating stratum parameters by conditioning on the total event count in each stratum, thus simplifying the computing and increasing the number of strata for which fitting is feasible compared with the standard unconditional Poisson model. Unlike the conditional logistic model, the conditional Poisson model does not require expanding the data, and can adjust for overdispersion and auto-correlation. It is available in Stata, R, and other packages. By applying to some real data and using simulations, we demonstrate that conditional Poisson models were simpler to code and shorter to run than are conditional logistic analyses and can be fitted to larger data sets than possible with standard Poisson models. Allowing for overdispersion or autocorrelation was possible with the conditional Poisson model but when not required this model gave identical estimates to those from conditional logistic regression. Conditional Poisson regression models provide an alternative to case crossover analysis of stratified time series data with some advantages. The conditional Poisson model can also be used in other contexts in which primary control for confounding is by fine

Irreversibility and conditional probability

International Nuclear Information System (INIS)

Stuart, C.I.J.M.

1989-01-01

The mathematical entropy - unlike physical entropy - is simply a measure of uniformity for probability distributions in general. So understood, conditional entropies have the same logical structure as conditional probabilities. If, as is sometimes supposed, conditional probabilities are time-reversible, then so are conditional entropies and, paradoxically, both then share this symmetry with physical equations of motion. The paradox is, of course that probabilities yield a direction to time both in statistical mechanics and quantum mechanics, while the equations of motion do not. The supposed time-reversibility of both conditionals seems also to involve a form of retrocausality that is related to, but possibly not the same as, that described by Costa de Beaurgard. The retrocausality is paradoxically at odds with the generally presumed irreversibility of the quantum mechanical measurement process. Further paradox emerges if the supposed time-reversibility of the conditionals is linked with the idea that the thermodynamic entropy is the same thing as 'missing information' since this confounds the thermodynamic and mathematical entropies. However, it is shown that irreversibility is a formal consequence of conditional entropies and, hence, of conditional probabilities also. 8 refs. (Author)

Low Water Activity Induces the Production of Bioactive Metabolites in Halophilic and Halotolerant Fungi

Directory of Open Access Journals (Sweden)

Nina Gunde-Cimerman

2010-12-01

Full Text Available The aim of the present study was to investigate indigenous fungal communities isolated from extreme environments (hypersaline waters of solar salterns and subglacial ice, for the production of metabolic compounds with selected biological activities: hemolysis, antibacterial, and acetylcholinesterase inhibition. In their natural habitats, the selected fungi are exposed to environmental extremes, and therefore the production of bioactive metabolites was tested under both standard growth conditions for mesophilic microorganisms, and at high NaCl and sugar concentrations and low growth temperatures. The results indicate that selected halotolerant and halophilic species synthesize specific bioactive metabolites under conditions that represent stress for non-adapted species. Furthermore, adaptation at the level of the chemical nature of the solute lowering the water activity of the medium was observed. Increased salt concentrations resulted in higher hemolytic activity, particularly within species dominating the salterns. The appearance of antibacterial potential under stress conditions was seen in the similar pattern of fungal species as for hemolysis. The active extracts exclusively affected the growth of the Gram-positive bacterium tested, Bacillus subtilis. None of the extracts tested showed inhibition of acetylcholinesterase activity.

Ammonia effect on hydrogenotrophic methanogens and syntrophic acetate oxidizing bacteria

DEFF Research Database (Denmark)

Wang, Han; Fotidis, Ioannis; Angelidaki, Irini

2015-01-01

tested in the study; which is contradicting to the general belief that thermophilic methanogens are more vulnerable to high ammonia loads compared to mesophilic. This unexpected finding underlines the fact that the complete knowledge of ammonia inhibition effect on hydrogenotrophic methanogens is still...

Supplementary Material for: Lignocellulose-derived thin stillage composition and efficient biological treatment with a high-rate hybrid anaerobic bioreactor system

KAUST Repository

Oosterkamp, Margreet; Mé ndez-Garcí a, Celia; Kim, Chang-H.; Bauer, Stefan; Ibá ñ ez, Ana; Zimmerman, Sabrina; Hong, Pei-Ying; Cann, Isaac; Mackie, Roderick

2016-01-01

on these stillages at mesophilic (40 °C) and thermophilic (55 °C) temperatures to produce methane was demonstrated. The microbial communities involved were further characterized. Results Energy and sugar cane stillage have a high chemical oxygen demand (COD of 43

Fulltext PDF

Indian Academy of Sciences (India)

2005-09-15

Sep 15, 2005 ... phate, A TP - an energy-rich molecule which is the principal donor of energy in ... ture range in which these organisms grow is similar to that of the mesophiles which grow at ..... Researchers therefore think that our ultimate ...

Syntrophic interactions drive the hydrogen production from glucose at low temperature in microbial electrolysis cells

KAUST Repository

Lu, Lu; Xing, Defeng; Ren, Nanqi; Logan, Bruce E.

2012-01-01

H2 can be obtained from glucose by fermentation at mesophilic temperatures, but here we demonstrate that hydrogen can also be obtained from glucose at low temperatures using microbial electrolysis cells (MECs). H2 was produced from glucose at 4°C

Biotransformation of algal waste by biological fermentation

African Journals Online (AJOL)

GRACE

2006-07-03

Jul 3, 2006 ... garbage contains different groups of bacteria whose number is variable: the total aerobic mesophilic ... was obtained after heating to a temperature of 550°C for. 24 h. ... solution 1 ml and made up to 1000 ml distilled water and.

Author Details

African Journals Online (AJOL)

Mesophilic Co-Digestion of Cattle Paunch with Poultry Droppings: Mixture Effect Assessment on Biogas Production Potentials Abstract PDF · Vol 35, No 4 (2016) - Agricultural, Bioresources, Biomedical, Food, Environmental & Water Resources Engineering Spatial statistics of poultry production in Anambra state of Nigeria: ...

Transformation of tetrachloroethene in an upflow anaerobic sludgeblanket reactor

DEFF Research Database (Denmark)

Christiansen, N.; Christensen, S.R.; Arvin, E.

1997-01-01

Reductive dechlorination of tetrachloroethene was studied in a mesophilic upflow anaerobic sludge blanket reactor. Operating the reactor in batch mode the dynamic transformation of tetrachloroethene, trichloroethene and dichloroethene (DCE) was monitored. Tetrachloroethene was reductively...... methane-producing bacteria were inhibited by the chlorinated ethenes....

MICROBIOLOGICAL QUALITY OF CONFECTIONARY PRODUCTS

Directory of Open Access Journals (Sweden)

Ľubomíra Juhaniaková

2013-02-01

Full Text Available The aim of this work was to determine microbiological quality of confectionery products. In confectionery products microbiological parameters: total count of bacteria, coliforms bacteria,mesophilic aerobes bacteria and microscopic filamentous fungi were observed. The confectionery products were evaluated: Kremeš and Venčekcake. For microbiological tests 20 samples of confectionery products were used. The numbers of total count of bacteria ranged from 3.29 log CFU.g-1, the number of mesophilic aerobes bacteria ranged from 1.86 to 2.85 log CFU.g-1, coliforms bacteria in confectionery products ranged from 0to 2.06CFU.g-1and the number of microscopic fungi ranged from 1.13 to 1.96CFU.g-1. The samples of cake prom private production showed better microbiological quality as samples from market production. All investigated samples of confectionary products were inaccordance with the Codex Alimentarius of the Slovak Republic.

Use of Propolis in the Sanitization of Lettuce

Directory of Open Access Journals (Sweden)

Xesús Feás

2014-07-01

Full Text Available The present study aimed to determine the effectiveness of propolis in reducing the microbial load in ready-to-eat (RTE and fresh whole head (FWH lettuces (Lactuca sativa L. type Batavia. Two sanitizing solutions were employed: sodium hypochlorite (SH and propolis (PS, during 15 and 30 min. Tap water (TW was used as a control. Regarding the mean reduction on aerobic mesophiles, psychrotrophic and fecal coliforms, the SH and PS treatments showed the same pattern of variation. In all cases, PS was slightly more effective in the microbiological reduction in comparison with commercial SH. Reductions between two and three log cycles were obtained with PS on aerobic mesophiles and psychrotrophic counts. The information obtained in the present study can be used to evaluate the potential use of propolis as product for sanitizing other vegetables and for developing other food preservation technologies, with impact on human health.

Fermentative hydrogen production by diverse microflora

International Nuclear Information System (INIS)

Baghchehsaraee, B.; Nakhla, G.; Karamanev, D.; Margaritis, A.

2009-01-01

'Full text': In this study of hydrogen production with activated sludge, a diverse bacterial source has been investigated and compared to microflora from anaerobic digester sludge, which is less diverse. Batch experiments were conducted at mesophilic (37 o C) and thermophilic (55 o C) temperatures. The hydrogen production yields with activated sludge at 37 o C and 55 o C were 0.25 and 0.93 mol H 2 /mol glucose, respectively. The maximum hydrogen production rates with activated sludge in both temperatures were 4.2 mL/h. Anaerobic digester sludge showed higher hydrogen production yields and rates at both mesophilic and thermophilic temperatures. The results of repeated batch experiments with activated sludge showed an increase in the hydrogen production during the consecutive batches. However, hydrogen production was not stable along the repeated batches. The observed instability was due to the formation of lactic acid and ethanol. (author)

Mining anaerobic digester consortia metagenomes for secreted carbohydrate active enzymes

DEFF Research Database (Denmark)

Wilkens, Casper; Busk, Peter Kamp; Pilgaard, Bo

thermophilic and mesophilic ADs a wide variety of carbohydrate active enzyme functions were discovered in the metagenomic sequencing of the microbial consortia. The most dominating type of glycoside hydrolases were β-glucosidases (up to 27%), α-amylases (up to 10%), α-glucosidases (up to 8%), α......, and food wastes (Alvarado et al., 2014). The processes and the roles of the microorganisms that are involved in biomass conversion and methane production in ADs are still not fully understood. We are investigating thermophilic and mesophilic ADs that use wastewater surplus sludge for methane production...... was done with the Peptide Pattern Recognition (PPR) program (Busk and Lange, 2013), which is a novel non-alignment based approach that can predict function of e.g. CAZymes. PPR identifies a set of short conserved sequences, which can be used as a finger print when mining genomes for novel enzymes. In both...

Microbiological studies of irradiated dried mackerel (Cybium guttatum Bloch and Schnieder)

International Nuclear Information System (INIS)

Ahmed, M.; Joardar, S.K.; Bhuiya, A.D.; Islam, M.S.

1985-01-01

Microbiological studies of sun-dried mackerel fish, Cybium guttatum, were conducted by exposing the fish to doses of gamma-rays from 0.50 to 8.00 kGy at the storage temperatures of 10.20 and 30oC. The reduction of bacterial flora was determined both qualitatively and quantitatively. At 4 kGyone log cycle reduction of bacterial flora was achieved and at 8 kGy the reduction was nearly 2 log cycles. The irradiated samples were stored for two months and viable bacterial counts were taken. Except in a few cases, reduction in viable counts occurred. Bacterial isolates were made and both Mesophiles and Psychrophiles were identified. Micrococcus, Staphylococcus, Corymebacterium and some Bacillus were found to be the prominent groups in mesophiles, while Bacillus dominated in psychrophiles. Staphylococcus was found to be the most dominant bacterial flora in unirradiated samples, but they were highly affected by irradiation

Fate of pathogens and micro-pollutants during organic wastes and by-products anaerobic digestion - a review; Etat des connaissances sur le devenir des germes pathogenes et des micropolluants au cours de la methanisation des dechets et sous-produits organiques

Energy Technology Data Exchange (ETDEWEB)

Couturier, Ch; Galtier, L

1998-09-01

Based on 300 scientific papers, the following bibliographical research deals with the fate of micro-pollutants (pathogens, heavy metals, organic pollutants) during anaerobic digestion. Different biological and chemical mechanisms allow organic compounds elimination, except from some Polycyclic Aromatic Hydrocarbons (PAHs) and heavy metals which are fixed to the solid biomass, permitting water contamination risks attenuation. Unlike mesophilic digestion, thermophilic digestion is a 'sanitation' process regarding pathogens elimination. However, mesophilic digestion offers an important reliability compared with competitive or complementary processes. In particular, energy recovery from anaerobic digestion allows temperature control and makes easier further sanitation heat treatments. In general, anaerobic digestion represents a tool which can be included in an organic waste treatment line assuming waste selection and good agricultural practices. Otherwise, sanitation problem is still badly handled by waste operators and constructors which have been consulted. Research orientations seem especially interesting in improving knowledge of real industrial processes performances. (author)

Evolutions of Yang Phase Under Cyclic Condition and Adiabatic Condition

International Nuclear Information System (INIS)

Qian Shangwu; Gu Zhiyu

2005-01-01

There are three non-integrable phases in literatures: Berry phase, Aharonov-Anandan phase, and Yang phase. This article discusses the evolutions of Yang phase under the cyclic condition and the adiabatic condition for the general time-dependent harmonic oscillator, thus reveals the intimate relations between these three non-integrable phases.

The Biocatalytic Potential of Extremophiles and Extremozymes

Directory of Open Access Journals (Sweden)

Walter Steiner

2004-01-01

Full Text Available Extremophiles are bizarre microorganisms that can grow and thrive in extreme environments, which were formerly considered too hostile to support life. The extreme conditions may be high or low temperature, high or low pH, high salinity, high metal concentrations, very low nutrient content, very low water activity, high radiation, high pressure and low oxygen tension. Some extremophiles are subject to multiple stress conditions. Extremophiles are structurally adapted at the molecular level to withstand these harsh conditions. The biocatalysts, called extremozymes, produced by these microorganisms, are proteins that function under extreme conditions. Due to their extreme stability, extremozymes offer new opportunities for biocatalysis and biotransformation. Examples of extremozymes include cellulases, amylases, xylanases, proteases, pectinases, keratinases, lipases, esterases, catalases, peroxidases and phytases, which have great potential for application in various biotechnological processes. Currently, only 1–2 % of the microorganisms on the Earth have been commercially exploited and amongst these there are only a few examples of extremophiles. However, the renewed interest that is currently emerging as a result of new developments in the cultivation and production of extremophiles and success in the cloning and expression of their genes in mesophilic hosts will increase the biocatalytic applications of extremozymes.

Substrate Type and Free Ammonia Determine Bacterial Community Structure in Full-Scale Mesophilic Anaerobic Digesters Treating Cattle or Swine Manure.

Science.gov (United States)

Li, Jiabao; Rui, Junpeng; Yao, Minjie; Zhang, Shiheng; Yan, Xuefeng; Wang, Yuanpeng; Yan, Zhiying; Li, Xiangzhen

2015-01-01

The microbial-mediated anaerobic digestion (AD) process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA) play key roles in determining the bacterial community structure. The COD: [Formula: see text] (C:N) ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters.

Development of an efficient anaerobic co-digestion process for garbage, excreta, and septic tank sludge to create a resource recycling-oriented society.

Science.gov (United States)

Sun, Zhao-Yong; Liu, Kai; Tan, Li; Tang, Yue-Qin; Kida, Kenji

2017-03-01

In order to develop a resource recycling-oriented society, an efficient anaerobic co-digestion process for garbage, excreta and septic tank sludge was studied based on the quantity of each biomass waste type discharged in Ooki machi, Japan. The anaerobic digestion characteristics of garbage, excreta and 5-fold condensed septic tank sludge (hereafter called condensed sludge) were determined separately. In single-stage mesophilic digestion, the excreta with lower C/N ratios yielded lower biogas volumes and accumulated higher volumes of volatile fatty acid (VFA). On the other hand, garbage allowed for a significantly larger volatile total solid (VTS) digestion efficiency as well as biogas yield by thermophilic digestion. Thus, a two-stage anaerobic co-digestion process consisting of thermophilic liquefaction and mesophilic digestion phases was proposed. In the thermophilic liquefaction of mixed condensed sludge and household garbage (wet mass ratio of 2.2:1), a maximum VTS loading rate of 24g/L/d was achieved. In the mesophilic digestion of mixed liquefied material and excreta (wet mass ratio of 1:1), biogas yield reached approximately 570ml/g-VTS fed with a methane content of 55% at a VTS loading rate of 1.0g/L/d. The performance of the two-stage process was evaluated by comparing it with a single-stage process in which biomass wastes were treated separately. Biogas production by the two-stage process was found to increase by approximately 22.9%. These results demonstrate the effectiveness of a two-stage anaerobic co-digestion process in enhancement of biogas production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biphasic Study to Characterize Agricultural Biogas Plants by High-Throughput 16S rRNA Gene Amplicon Sequencing and Microscopic Analysis.

Science.gov (United States)

Maus, Irena; Kim, Yong Sung; Wibberg, Daniel; Stolze, Yvonne; Off, Sandra; Antonczyk, Sebastian; Pühler, Alfred; Scherer, Paul; Schlüter, Andreas

2017-02-28

Process surveillance within agricultural biogas plants (BGPs) was concurrently studied by high-throughput 16S rRNA gene amplicon sequencing and an optimized quantitative microscopic fingerprinting (QMF) technique. In contrast to 16S rRNA gene amplicons, digitalized microscopy is a rapid and cost-effective method that facilitates enumeration and morphological differentiation of the most significant groups of methanogens regarding their shape and characteristic autofluorescent factor 420. Moreover, the fluorescence signal mirrors cell vitality. In this study, four different BGPs were investigated. The results indicated stable process performance in the mesophilic BGPs and in the thermophilic reactor. Bacterial subcommunity characterization revealed significant differences between the four BGPs. Most remarkably, the genera Defluviitoga and Halocella dominated the thermophilic bacterial subcommunity, whereas members of another taxon, Syntrophaceticus , were found to be abundant in the mesophilic BGP. The domain Archaea was dominated by the genus Methanoculleus in all four BGPs, followed by Methanosaeta in BGP1 and BGP3. In contrast, Methanothermobacter members were highly abundant in the thermophilic BGP4. Furthermore, a high consistency between the sequencing approach and the QMF method was shown, especially for the thermophilic BGP. The differences elucidated that using this biphasic approach for mesophilic BGPs provided novel insights regarding disaggregated single cells of Methanosarcina and Methanosaeta species. Both dominated the archaeal subcommunity and replaced coccoid Methanoculleus members belonging to the same group of Methanomicrobiales that have been frequently observed in similar BGPs. This work demonstrates that combining QMF and 16S rRNA gene amplicon sequencing is a complementary strategy to describe archaeal community structures within biogas processes.

Microbiological quality of goat milk on rural properties in the region of Macaíba/RN

Directory of Open Access Journals (Sweden)

Joyce Bruna Paiva Silva

2018-02-01

Full Text Available Goat’s milk is an excellent food that can guarantee beneficial effects to human health, but its characteristics are easily altered by the action of microorganisms and by manipulation. The present study aimed to evaluate the microbiological quality of goat milk in 11 farms in the region of Macaíba/RN. Samples of milk and swabs from the hands of milkers, utensils and goat teats were collected and transported in a thermal box (10 ºC – 12 ºC to the Laboratory of Food Engineering of UFRN. The microorganisms studied were the aerobic mesophilic bacteria, psychrotrophic, coagulase positive and negative staphylococci, coliforms at 35 ºC and 45 ºC. Regarding the hands of milkers, 56% presented contamination by aerobic mesophilic bacteria. In the analyzed utensils were found, in 18.2%, coliforms at 45 ºC and coagulase positive staphylococci, as well as coagulase negative staphylococci (63.6% and coliforms at 35 ºC in 27.3% of the samples. For cold raw goat milk, 10% of the samples presented contamination with psychrotrophic and 17% with coliforms at 45 ºC. Regarding goat teats, 52% of the samples had aerobic mesophilic bacteria counts above 103 CFU/ceiling, 61% presented coagulase negative staphylococci and 10% coagulase positive staphylococci, this one of the main agents causing mastitis. Thus, these values indicate that hygienic procedures need to be adopted appropriately in the milking of raw goat milk, requiring guidelines that enable producers to obtain higher quality milk.

Conditional Aid Effectiveness

DEFF Research Database (Denmark)

Doucouliagos, Hristos; Paldam, Martin

of the differences in results between studies. Taking all available studies in consideration, we find no support for conditionality with respect to policy, while conditionality regarding aid itself is dubious. However, the results differ depending on the authors’ institutional affiliation....

Development of fermented milk “Leben” made from spontaneous ...

African Journals Online (AJOL)

Yomi

2012-01-24

Jan 24, 2012 ... shaking it back and forth till the coalescence of the fat globules. ... proteins, mesophilic lactis acid bacteria (LAB) were the predominant ... the following steps: five liters of raw milk was left spontaneously at. 25 ± 2°C in a jar ...

Waterborne Exophiala species causing disease in cold-blooded animals

NARCIS (Netherlands)

de Hoog, G.S.; Vicente, V.A.; Najafzadeh, M.J.; Harrak, M.J.; Badali, H.; Seyedmousavi, S.

2011-01-01

The majority of mesophilic waterborne species of the black yeast genus Exophiala (Chaetothyriales) belong to a single clade judging from SSU rDNA data. Most taxa are also found to cause cutaneous or disseminated infections in cold-blooded, water animals, occasionally reaching epidemic proportions.

Waterborne Exophiala species causing disease in cold-blooded animals

NARCIS (Netherlands)

de Hoog, G.S.; Vicente, V.A.; Najafzadeh, M.J.; Harrak, M.J.; Badali, H.; Seyedmousavi, S.

2012-01-01

The majority of mesophilic waterborne species of the black yeast genus Exophiala (Chaetothyriales) belong to a single clade judging from SSU rDNA data. Most taxa are also found to cause cutaneous or disseminated infections in cold-blooded, water animals, occasionally reaching epidemic proportions.

Microbial (per)chlorate reduction in hot subsurface environments

NARCIS (Netherlands)

Liebensteiner, M.

2014-01-01

The microbial reduction of chlorate and perchlorate has been known for long as a respiratory process of mesophilic bacteria that thrive in diverse environments such as soils, marine and freshwater sediments. Chlorate and perchlorate are found in nature deriving from anthropogenic and natural

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