A meta-analysis of soil microbial biomass responses to forest disturbances

Directory of Open Access Journals (Sweden)

Sandra Robin Holden

2013-06-01

Full Text Available Climate warming is likely to increase the frequency and severity of forest disturbances, with uncertain consequences for soil microbial communities and their contribution to ecosystem C dynamics. To address this uncertainty, we conducted a meta-analysis of 139 published soil microbial responses to forest disturbances. These disturbances included abiotic (fire, harvesting, storm and biotic (insect, pathogen disturbances. We hypothesized that soil microbial biomass would decline following forest disturbances, but that abiotic disturbances would elicit greater reductions in microbial biomass than biotic disturbances. In support of this hypothesis, across all published studies, disturbances reduced soil microbial biomass by an average of 29.4%. However, microbial responses differed between abiotic and biotic disturbances. Microbial responses were significantly negative following fires, harvest, and storms (48.7%, 19.1%, and 41.7% reductions in microbial biomass, respectively. In contrast, changes in soil microbial biomass following insect infestation and pathogen-induced tree mortality were non-significant, although biotic disturbances were poorly represented in the literature. When measured separately, fungal and bacterial responses to disturbances mirrored the response of the microbial community as a whole. Changes in microbial abundance following disturbance were significantly positively correlated with changes in microbial respiration. We propose that the differential effect of abiotic and biotic disturbances on microbial biomass may be attributable to differences in soil disruption and organic C removal from forests among disturbance types. Altogether, these results suggest that abiotic forest disturbances may significantly decrease soil microbial abundance, with corresponding consequences for microbial respiration. Further studies are needed on the effect of biotic disturbances on forest soil microbial communities and soil C dynamics.

Nutrients and temperature additively increase stream microbial respiration

Science.gov (United States)

David W. P. Manning; Amy D. Rosemond; Vladislav Gulis; Jonathan P. Benstead; John S. Kominoski

2017-01-01

Rising temperatures and nutrient enrichment are co‐occurring global‐change drivers that stimulate microbial respiration of detrital carbon, but nutrient effects on the temperature dependence of respiration in aquatic ecosystems remain uncertain. We measured respiration rates associated with leaf litter, wood, and fine benthic organic matter (FBOM) across...

Soil microbial responses to nitrogen addition in arid ecosystems

Directory of Open Access Journals (Sweden)

Robert L Sinsabaugh

2015-08-01

Full Text Available The N cycle of arid ecosystems is influenced by low soil organic matter, high soil pH and extremes in water potential and temperature that lead to open canopies and development of biological soil crusts (biocrusts. We investigated the effects of N amendment on soil microbial dynamics in a Larrea tridentata-Ambrosia dumosa shrubland site in southern Nevada USA. Sites were fertilized with a NO3-NH4 mix at 0, 7, and 15 kg ha-1 yr-1 from March 2012 to March 2013. In March 2013, biocrust (0-0.5 cm and bulk soils (0-10 cm were collected beneath Ambrosia canopies and in the interspaces between plants. Biomass responses were assessed as bacterial and fungal SSU rRNA gene copy number and chlorophyll a concentration. Metabolic responses were measured by five ecoenzyme activities (EEA and rates of N transformation. By most measures, nutrient availability, microbial biomass and process rates were greater in soils beneath the shrub canopy compared to the interspace between plants, and greater in the surface biocrust horizon compared to the deeper 10 cm soil profile. Most measures responded positively to experimental N addition. Effect sizes were generally greater for bulk soil than biocrust. Results were incorporated into a meta-analysis of arid ecosystem responses to N.

Microbial response of an acid forest soil to experimental soil warming

Science.gov (United States)

S.S. Arnold; I.J. Fernandez; L.E. Rustad; L.M. Zibilske

1999-01-01

Effects of increased soil temperature on soil microbial biomass and dehydrogenase activity were examined on organic (O) horizon material in a low-elevation spruce-fir ecosystem. Soil temperature was maintained at 5 °C above ambient during the growing season in the experimental plots, and soil temperature, moisture, microbial biomass, and dehydrogenase activity were...

Shifts in the Physiology and Stoichiometric Needs of Soil Microbial Communities from Subarctic Soils in Response to Warming: Icelandic Geothermal Gradients as a Model.

Science.gov (United States)

Marañón-Jiménez, S.; Soong, J.; Leblans, N. I. W.; Sigurdsson, B. D.; Peñuelas, J.; Richter, A.; Asensio, D.; Fransen, E.; Janssens, I. A.

2017-12-01

Large amounts of CO2 can be released to the atmosphere from a faster mineralization of soil organic matter at warmer temperatures, thus inducing climate change feedbacks. Specifically, soils at high northern latitudes store more than half of the global surface soil carbon and are particularly vulnerable to temperature-driven C losses, since they warm more rapidly. Alterations to the temperature sensitivity, physiological functioning and stoichiometric constrains of soil microorganisms in response to rising temperatures can play a key role in these soil carbon (C) losses. We present results of several incubation experiments using soils from geothermal soil temperature gradients in Iceland that have undergone a range of warming intensities for seven years, encompassing the full range of IPCC warming scenarios for the northern region. Soil microbes from warmed soils did not show changes in their temperature sensitivity at the physiological level. On the contrary, seven years of chronic soil warming provoked a permanent increase of microbial metabolic quotients (i.e., respiration per unit of biomass), and a subsequent reduction in the C retained in biomass as substrate became limiting. After the initial depletion of labile soil C, increasing energy demands for metabolic maintenance and resource acquisition at higher temperatures may have triggered permanent functional changes or community shifts towards increasing respiratory costs of soil decomposers. Pointing to this, microbial communities showed a strong C limitation even at ambient soil temperatures, obscuring any metabolic response to nitrogen and phosphorous additions. The tight C:N stoichiometric constrains of soil microbial communities and the strong C limitation for microbial biomass may lead to a reduced capacity of microbial N retention, explaining the equivalent soil C and N losses found in response to soil warming. These results highlight the need to incorporate potential changes in microbial physiological

Similar temperature dependencies of glycolytic enzymes : An evolutionary adaptation to temperature dynamics?

NARCIS (Netherlands)

Cruz, L.A.B.; Hebly, M.; Duong, G.H.; Wahl, S.A.; Pronk, J.T.; Heijnen, J.J.; Daran-Lapujade, P.; Van Gulik, W.M.

2012-01-01

Background Temperature strongly affects microbial growth, and many microorganisms have to deal with temperature fluctuations in their natural environment. To understand regulation strategies that underlie microbial temperature responses and adaptation, we studied glycolytic pathway kinetics in

Effects of microbial loading and sporulation temperature on atmospheric plasma inactivation of Bacillus subtilis spores

Science.gov (United States)

Deng, X. T.; Shi, J. J.; Shama, G.; Kong, M. G.

2005-10-01

Current inactivation studies of Bacillus subtilis spores using atmospheric-pressure glow discharges (APGD) do not consider two important factors, namely microbial loading at the surface of a substrate and sporulation temperature. Yet these are known to affect significantly microbial resistance to heat and hydrogen peroxide. This letter investigates effects of microbial loading and sporulation temperature on spore resistance to APGD. It is shown that microbial loading can lead to a stacking structure as a protective shield against APGD treatment and that high sporulation temperature increases spore resistance by altering core water content and cross-linked muramic acid content of B. subtilis spores.

Humboldt's spa: microbial diversity is controlled by temperature in geothermal environments.

Science.gov (United States)

Sharp, Christine E; Brady, Allyson L; Sharp, Glen H; Grasby, Stephen E; Stott, Matthew B; Dunfield, Peter F

2014-06-01

Over 200 years ago Alexander von Humboldt (1808) observed that plant and animal diversity peaks at tropical latitudes and decreases toward the poles, a trend he attributed to more favorable temperatures in the tropics. Studies to date suggest that this temperature-diversity gradient is weak or nonexistent for Bacteria and Archaea. To test the impacts of temperature as well as pH on bacterial and archaeal diversity, we performed pyrotag sequencing of 16S rRNA genes retrieved from 165 soil, sediment and biomat samples of 36 geothermal areas in Canada and New Zealand, covering a temperature range of 7.5-99 °C and a pH range of 1.8-9.0. This represents the widest ranges of temperature and pH yet examined in a single microbial diversity study. Species richness and diversity indices were strongly correlated to temperature, with R(2) values up to 0.62 for neutral-alkaline springs. The distributions were unimodal, with peak diversity at 24 °C and decreasing diversity at higher and lower temperature extremes. There was also a significant pH effect on diversity; however, in contrast to previous studies of soil microbial diversity, pH explained less of the variability (13-20%) than temperature in the geothermal samples. No correlation was observed between diversity values and latitude from the equator, and we therefore infer a direct temperature effect in our data set. These results demonstrate that temperature exerts a strong control on microbial diversity when considered over most of the temperature range within which life is possible.

Microbial Metabolism in Soil at Subzero Temperatures: Adaptation Mechanisms Revealed by Position-Specific 13C Labeling

Directory of Open Access Journals (Sweden)

Ezekiel K. Bore

2017-05-01

Full Text Available Although biogeochemical models designed to simulate carbon (C and nitrogen (N dynamics in high-latitude ecosystems incorporate extracellular parameters, molecular and biochemical adaptations of microorganisms to freezing remain unclear. This knowledge gap hampers estimations of the C balance and ecosystem feedback in high-latitude regions. To analyze microbial metabolism at subzero temperatures, soils were incubated with isotopomers of position-specifically 13C-labeled glucose at three temperatures: +5 (control, -5, and -20°C. 13C was quantified in CO2, bulk soil, microbial biomass, and dissolved organic carbon (DOC after 1, 3, and 10 days and also after 30 days for samples at -20°C. Compared to +5°C, CO2 decreased 3- and 10-fold at -5 and -20°C, respectively. High 13C recovery in CO2 from the C-1 position indicates dominance of the pentose phosphate pathway at +5°C. In contrast, increased oxidation of the C-4 position at subzero temperatures implies a switch to glycolysis. A threefold higher 13C recovery in microbial biomass at -5 than +5°C points to synthesis of intracellular compounds such as glycerol and ethanol in response to freezing. Less than 0.4% of 13C was recovered in DOC after 1 day, demonstrating complete glucose uptake by microorganisms even at -20°C. Consequently, we attribute the fivefold higher extracellular 13C in soil than in microbial biomass to secreted antifreeze compounds. This suggests that with decreasing temperature, intracellular antifreeze protection is complemented by extracellular mechanisms to avoid cellular damage by crystallizing water. The knowledge of sustained metabolism at subzero temperatures will not only be useful for modeling global C dynamics in ecosystems with periodically or permanently frozen soils, but will also be important in understanding and controlling the adaptive mechanisms of food spoilage organisms.

Different Mechanisms of Soil Microbial Response to Global Change Result in Different Outcomes in the MIMICS-CN Model

Science.gov (United States)

Kyker-Snowman, E.; Wieder, W. R.; Grandy, S.

2017-12-01

Microbial-explicit models of soil carbon (C) and nitrogen (N) cycling have improved upon simulations of C and N stocks and flows at site-to-global scales relative to traditional first-order linear models. However, the response of microbial-explicit soil models to global change factors depends upon which parameters and processes in a model are altered by those factors. We used the MIcrobial-MIneral Carbon Stabilization Model with coupled N cycling (MIMICS-CN) to compare modeled responses to changes in temperature and plant inputs at two previously-modeled sites (Harvard Forest and Kellogg Biological Station). We spun the model up to equilibrium, applied each perturbation, and evaluated 15 years of post-perturbation C and N pools and fluxes. To model the effect of increasing temperatures, we independently examined the impact of decreasing microbial C use efficiency (CUE), increasing the rate of microbial turnover, and increasing Michaelis-Menten kinetic rates of litter decomposition, plus several combinations of the three. For plant inputs, we ran simulations with stepwise increases in metabolic litter, structural litter, whole litter (structural and metabolic), or labile soil C. The cumulative change in soil C or N varied in both sign and magnitude across simulations. For example, increasing kinetic rates of litter decomposition resulted in net releases of both C and N from soil pools, while decreasing CUE produced short-term increases in respiration but long-term accumulation of C in litter pools and shifts in soil C:N as microbial demand for C increased and biomass declined. Given that soil N cycling constrains the response of plant productivity to global change and that soils generate a large amount of uncertainty in current earth system models, microbial-explicit models are a critical opportunity to advance the modeled representation of soils. However, microbial-explicit models must be improved by experiments to isolate the physiological and stoichiometric

New steady-state microbial community compositions and process performances in biogas reactors induced by temperature disturbances

DEFF Research Database (Denmark)

Luo, Gang; De Francisci, Davide; Kougias, Panagiotis

2015-01-01

that stochastic factors had a minor role in shaping the profile of the microbial community composition and activity in biogas reactors. On the contrary, temperature disturbance was found to play an important role in the microbial community composition as well as process performance for biogas reactors. Although...... three different temperature disturbances were applied to each biogas reactor, the increased methane yields (around 10% higher) and decreased volatile fatty acids (VFAs) concentrations at steady state were found in all three reactors after the temperature disturbances. After the temperature disturbance...... in shaping the profile of the microbial community composition and activity in biogas reactors. New steady-state microbial community profiles and reactor performances were observed in all the biogas reactors after the temperature disturbance....

Carbon use efficiency (CUE) and biomass turnover of soil microbial communities as affected by bedrock, land management and soil temperature and moisture

Science.gov (United States)

Zheng, Qing; Hu, Yuntao; Richter, Andreas; Wanek, Wolfgang

2017-04-01

Soil microbial carbon use efficiency (CUE), defined as the proportion of organic C taken up that is allocated to microbial growth, represents an important synthetic representation of microbial community C metabolism that describes the flux partitioning between microbial respiration and growth. Therefore, studying microbial CUE is critical for the understanding of soil C cycling. Microbial CUE is thought to vary with environmental conditions (e.g. temperature and soil moisture). Microbial CUE is thought to decrease with increasing temperature and declining soil moisture, as the latter may trigger stress responses (e.g. the synthesis of stress metabolites), which may consequently lower microbial community CUE. However, these effects on microbial CUE have not been adequately measured so far due to methodological restrictions. The most widely used methods for microbial CUE estimation are based on tracing 13C-labeled substrates into microbial biomass and respiratory CO2, approaches that are known to overestimate microbial CUE of native organic matter in soil. Recently, a novel substrate-independent approach based on the measurement of (i) respiration rates and (ii) the incorporation rates of 18O from labelled water into newly formed microbial DNA has been developed in our laboratory for measuring microbial CUE. This approach overcomes the shortcomings of previously used methods and has already been shown to yield realistic estimations of soil microbial CUE. This approach can also be applied to concurrently measure microbial biomass turnover rates, which also influence the sequestration of soil organic C. Microbial turnover rates are also thought to be impacted by environmental factors, but rarely have been directly measured so far. Here, we aimed at determining the short-term effects of environmental factors (soil temperature and soil moisture) on microbial CUE and microbial biomass turnover rates based on the novel 18O approach. Soils from three land-use types (arable

Are Microbial Nanowires Responsible for Geoelectrical Changes at Hydrocarbon Contaminated Sites?

Science.gov (United States)

Hager, C.; Atekwana, E. A.; Gorby, Y. A.; Duris, J. W.; Allen, J. P.; Atekwana, E. A.; Ownby, C.; Rossbach, S.

2007-05-01

Significant advances in near-surface geophysics and biogeophysics in particular, have clearly established a link between geoelectrical response and the growth and enzymatic activities of microbes in geologic media. Recent studies from hydrocarbon contaminated sites suggest that the activities of distinct microbial populations, specifically syntrophic, sulfate reducing, and dissimilatory iron reducing microbial populations are a contributing factor to elevated sediment conductivity. However, a fundamental mechanistic understanding of the processes and sources resulting in the measured electrical response remains uncertain. The recent discovery of bacterial nanowires and their electron transport capabilities suggest that if bacterial nanowires permeate the subsurface, they may in part be responsible for the anomalous conductivity response. In this study we investigated the microbial population structure, the presence of nanowires, and microbial-induced alterations of a hydrocarbon contaminated environment and relate them to the sediments' geoelectrical response. Our results show that microbial communities varied substantially along the vertical gradient and at depths where hydrocarbons saturated the sediments, ribosomal intergenic spacer analysis (RISA) revealed signatures of microbial communities adapted to hydrocarbon impact. In contrast, RISA profiles from a background location showed little community variations with depth. While all sites showed evidence of microbial activity, a scanning electron microscope (SEM) study of sediment from the contaminated location showed pervasive development of "nanowire-like structures" with morphologies consistent with nanowires from laboratory experiments. SEM analysis suggests extensive alteration of the sediments by microbial Activity. We conclude that, excess organic carbon (electron donor) but limited electron acceptors in these environments cause microorganisms to produce nanowires to shuttle the electrons as they seek for

Spatio-temporal reproducibility of the microbial food web structure associated with the change in temperature: Long-term observations in the Adriatic Sea

Science.gov (United States)

Šolić, Mladen; Grbec, Branka; Matić, Frano; Šantić, Danijela; Šestanović, Stefanija; Ninčević Gladan, Živana; Bojanić, Natalia; Ordulj, Marin; Jozić, Slaven; Vrdoljak, Ana

2018-02-01

Global and atmospheric climate change is altering the thermal conditions in the Adriatic Sea and, consequently, the marine ecosystem. Along the eastern Adriatic coast sea surface temperature (SST) increased by an average of 1.03 °C during the period from 1979 to 2015, while in the recent period, starting from 2008, a strong upward almost linear trend of 0.013 °C/month was noted. Being mainly oligotrophic, the middle Adriatic Sea is characterized by the important role played by the microbial food web in the production and transfer of biomass and energy towards higher trophic levels. It is very important to understand the effect of warming on microbial communities, since small temperature increases in surface seawater can greatly modify the microbial role in the global carbon cycle. In this study, the Self-Organizing Map (SOM) procedure was used to analyse the time series of a number of microbial parameters at two stations with different trophic status in the central Adriatic Sea. The results show that responses of the microbial food web (MFW) structure to temperature changes are reproducible in time. Furthermore, qualitatively similar changes in the structure of the MFW occurred regardless of the trophic status. The rise in temperature was associated with: (1) the increasing importance of microbial heterotrophic activities (increase bacterial growth and bacterial predator abundance, particularly heterotrophic nanoflagellates) and (2) the increasing importance of autotrophic picoplankton (APP) in the MFW.

Soil microbial community response to land use and various soil ...

African Journals Online (AJOL)

Soil microbial community response to land use and various soil elements in a city landscape of north China. ... African Journal of Biotechnology ... Legumes played an important role in stimulating the growth and reproduction of various soil microbial populations, accordingly promoting the microbial catabolic activity.

Electricity generation of single-chamber microbial fuel cells at low temperatures

KAUST Repository

Cheng, Shaoan; Xing, Defeng; Logan, Bruce E.

2011-01-01

Practical applications of microbial fuel cells (MFCs) for wastewater treatment will require operation of these systems over a wide range of wastewater temperatures. MFCs at room or higher temperatures (20-35°C) are relatively well studied compared

Response of microbial communities to experimental warming and precipitation decrease in Rzecin peatland (Poland)

Science.gov (United States)

Basińska, Anna M.; Gąbka, Maciej; Reczuga, Monika; Łuców, Dominika; Stróżecki, Marcin; Samson, Mateusz; Józefczyk, Damian; Chojnicki, Bogdan; Urbaniak, Marek; Leśny, Jacek; Olejnik, Janusz; Gilbert, Daniel; Silvennoinen, Hanna; Juszczak, Radosław; Lamentowicz, Mariusz

2017-04-01

In the last decade researchers are intensively testing the consequences of different climate change scenarios. Due to high biodiversity, huge amount of stored carbon and their sensitivity to environmental changes, peatlands became important for the temperature increase and drought experiments. Analyses showed that mosses, vascular plants and microbial communities were affected by warming or drought, but still not all effects are clear. Studying the response of microbial groups and indicators (e.g. mixotrophic species of testate amoeba) to warming in combination with decrease of precipitation will allow to better understand the future environmental changes. To recognize the inflow of organic matter and the carbon fixing processes in disturbed environment, we need to analyse the structure and biomass of main groups living in peatlands and the response of those groups to disturbances. The Polish - Norway "WETMAN" project was designed to recognize biotic and abiotic components of ecosystem response to active warming and decrease of precipitation. In this study we present the response of microbial communities and chosen testate amoeba species (TA) to different treatments: warming, warming and decreased precipitation and only decreased precipitation, in relation to control plots. The microbial biomass of upper and lower Sphagnum segments were analysed separately. Particular microbial groups were positively correlated with manipulations e. g. microalgae and rotifers, and other were negatively affected by combination of drought and warming e.g. cyanobacteria and testate amoeba. The structure of community was modified by manipulations, and differed in the case of upper and lower segment of Sphagnum. RDA analyses showed that different factors were crucial for the biomass of microbial groups in upper (conductivity, temperature and phosphorus) and lower (nitrates and sodium) segment. Considering higher taxonomic resolution we found that at the beginning of the experiment TA

Historical precipitation predictably alters the shape and magnitude of microbial functional response to soil moisture.

Science.gov (United States)

Averill, Colin; Waring, Bonnie G; Hawkes, Christine V

2016-05-01

Soil moisture constrains the activity of decomposer soil microorganisms, and in turn the rate at which soil carbon returns to the atmosphere. While increases in soil moisture are generally associated with increased microbial activity, historical climate may constrain current microbial responses to moisture. However, it is not known if variation in the shape and magnitude of microbial functional responses to soil moisture can be predicted from historical climate at regional scales. To address this problem, we measured soil enzyme activity at 12 sites across a broad climate gradient spanning 442-887 mm mean annual precipitation. Measurements were made eight times over 21 months to maximize sampling during different moisture conditions. We then fit saturating functions of enzyme activity to soil moisture and extracted half saturation and maximum activity parameter values from model fits. We found that 50% of the variation in maximum activity parameters across sites could be predicted by 30-year mean annual precipitation, an indicator of historical climate, and that the effect is independent of variation in temperature, soil texture, or soil carbon concentration. Based on this finding, we suggest that variation in the shape and magnitude of soil microbial response to soil moisture due to historical climate may be remarkably predictable at regional scales, and this approach may extend to other systems. If historical contingencies on microbial activities prove to be persistent in the face of environmental change, this approach also provides a framework for incorporating historical climate effects into biogeochemical models simulating future global change scenarios. © 2016 John Wiley & Sons Ltd.

Microbial phylogeny determines transcriptional response of resistome to dynamic composting processes.

Science.gov (United States)

Wang, Cheng; Dong, Da; Strong, P J; Zhu, Weijing; Ma, Zhuang; Qin, Yong; Wu, Weixiang

2017-08-16

Animal manure is a reservoir of antibiotic resistance genes (ARGs) that pose a potential health risk globally, especially for resistance to the antibiotics commonly used in livestock production (such as tetracycline, sulfonamide, and fluoroquinolone). Currently, the effects of biological treatment (composting) on the transcriptional response of manure ARGs and their microbial hosts are not well characterized. Composting is a dynamic process that consists of four distinct phases that are distinguished by the temperature resulting from microbial activity, namely the mesophilic, thermophilic, cooling, and maturing phases. In this study, changes of resistome expression were determined and related to active microbiome profiles during the dynamic composting process. This was achieved by integrating metagenomic and time series metatranscriptomic data for the evolving microbial community during composting. Composting noticeably reduced the aggregated expression level of the manure resistome, which primarily consisted of genes encoding for tetracycline, vancomycin, fluoroquinolone, beta-lactam, and aminoglycoside resistance, as well as efflux pumps. Furthermore, a varied transcriptional response of resistome to composting at the ARG levels was highlighted. The expression of tetracycline resistance genes (tetM-tetW-tetO-tetS) decreased during composting, where distinctive shifts in the four phases of composting were related to variations in antibiotic concentration. Composting had no effect on the expression of sulfonamide and fluoroquinolone resistance genes, which increased slightly during the thermophilic phase and then decreased to initial levels. As indigenous populations switched greatly throughout the dynamic composting, the core resistome persisted and their reservoir hosts' composition was significantly correlated with dynamic active microbial phylogenetic structure. Hosts for sulfonamide and fuoroquinolone resistance genes changed notably in phylognetic structure

Effect of temperature on shelf life, chemical and microbial properties ...

African Journals Online (AJOL)

Cream cheese samples were analyzed to find out the effect of recommended storage temperature (4±1°C) and ambient room temperature (21±1°C) on pH, titratable acidity (% lactic acid), moisture content and microbial growth. Percent reduction in moisture content and increase in titratable acidity of cheeses were found to ...

Soil Temperature and Moisture Effects on Soil Respiration and Microbial Community Abundance

Science.gov (United States)

2015-04-13

Bárcenas-Moreno, G., M. Gómez-Brandón, J. Rousk, and E. Bååth. 2009. Adaptation of soil microbial communities to temperature: Comparison of fungi and...ER D C/ CR RE L TR -1 5- 6 ERDC 6.2 Geospatial Research and Engineering (GRE) ARTEMIS TSP-SA Soil Temperature and Moisture Effects on... Soil Respiration and Microbial Community Abundance Co ld R eg io ns R es ea rc h an d En gi ne er in g La bo ra to ry Robyn A. Barbato

2010 MICROBIAL STRESS RESPONSE GORDON RESEARCH CONFERENCE, JULY 18-23, 2010

Energy Technology Data Exchange (ETDEWEB)

Sarah Ades

2011-07-23

The 2010 Gordon Research Conference on Microbial Stress Responses provides an open and exciting forum for the exchange of scientific discoveries on the remarkable mechanisms used by microbes to survive in nearly every niche on the planet. Understanding these stress responses is critical for our ability to control microbial survival, whether in the context of biotechnology, ecology, or pathogenesis. From its inception in 1994, this conference has traditionally employed a very broad definition of stress in microbial systems. Sessions will cover the major steps of stress responses from signal sensing to transcriptional regulation to the effectors that mediate responses. A wide range of stresses will be represented. Some examples include (but are not limited to) oxidative stress, protein quality control, antibiotic-induced stress and survival, envelope stress, DNA damage, and nutritional stress. The 2010 meeting will also focus on the role of stress responses in microbial communities, applied and environmental microbiology, and microbial development. This conference brings together researchers from both the biological and physical sciences investigating stress responses in medically- and environmentally relevant microbes, as well as model organisms, using cutting-edge techniques. Computational, systems-level, and biophysical approaches to exploring stress responsive circuits will be integrated throughout the sessions alongside the more traditional molecular, physiological, and genetic approaches. The broad range of excellent speakers and topics, together with the intimate and pleasant setting at Mount Holyoke College, provide a fertile ground for the exchange of new ideas and approaches.

Membrane fouling related to microbial community and extracellular polymeric substances at different temperatures.

Science.gov (United States)

Gao, Da-Wen; Wen, Zhi-Dan; Li, Bao; Liang, Hong

2013-09-01

An anoxic-aerobic membrane bioreactor was established to investigate the role of microorganisms and microbial metabolites in membrane fouling at different temperatures. The results showed that the membrane fouling cycle at 303, 293, and 283 K were 30, 29, and 5.5 days, respectively. Polysaccharides dominated the extracellular polymeric substances (EPS) and soluble microbial products (SMP) at 303 and 293 K, instead, proteins was the predominant composition of metabolites at 283 K. The correlation coefficient (r(2)) was calculated to identify the relationship between temperature (T), filtration resistance (R) and compositions of EPS and SMP. In biocake, the EPS polysaccharides (EPSc) was the most correlative factor to temperature (T) and filtration resistance (R); in mixed liquor, the ratio of SMP polysaccharides to proteins (SMPc/p) was the most correlative factor. The microbial community structure and the dominant species was the major reason causing the change of EPS and SMP composition. Copyright © 2013 Elsevier Ltd. All rights reserved.

Responses to microbial challenges by SLAMF receptors

Directory of Open Access Journals (Sweden)

Boaz Job Van Driel

2016-01-01

Full Text Available The SLAMF Family (SLAMF of cell surface glycoproteins is comprised of nine glycoproteins and whilst SLAMF1, 3, 5, 6, 7, 8, 9 are self-ligand receptors, SLAMF2 and SLAMF4 interact with each other. Their interactions induce signal transduction networks in trans, thereby shaping immune cell-cell communications. Collectively, these receptors modulate a wide range of functions, such as myeloid cell and lymphocyte development and, T and B cell responses to microbes and parasites. In addition, several SLAMF receptors serve as microbial sensors, which either positively or negatively modulate the function of macrophages, dendritic cells, neutrophils and NK cells in response to microbial challenges. The SLAMF receptor-microbe interactions contribute both to intracellular microbicidal activity as well as to migration of phagocytes to the site of inflammation. In this review, we describe the current knowledge on how the SLAMF receptors and their specific adapters SAP and EAT-2 regulate innate and adaptive immune responses to microbes.

Microbial impacts on geothermometry temperature predictions

Energy Technology Data Exchange (ETDEWEB)

Yoshiko Fujita; David W. Reed; Kaitlyn R. Nowak; Vicki S. Thompson; Travis L. McLing; Robert W. Smith

2013-02-01

Conventional geothermometry approaches assume that the composition of a collected water sample originating in a deep geothermal reservoir still reflects chemical equilibration of the water with the deep reservoir rocks. However, for geothermal prospecting samples whose temperatures have dropped to <120°C, temperature predictions may be skewed by the activity of microorganisms; microbial metabolism can drastically and rapidly change the water’s chemistry. We hypothesize that knowledge of microbial impacts on exploration sample geochemistry can be used to constrain input into geothermometry models and thereby improve the reliability of reservoir temperature predictions. To evaluate this hypothesis we have chosen to focus on sulfur cycling, because of the significant changes in redox state and pH associated with sulfur chemistry. Redox and pH are critical factors in defining the mineral-fluid equilibria that form the basis of solute geothermometry approaches. Initially we are developing assays to detect the process of sulfate reduction, using knowledge of genes specific to sulfate reducing microorganisms. The assays rely on a common molecular biological technique known as quantitative polymerase chain reaction (qPCR), which allows estimation of the number of target organisms in a particular sample by enumerating genes specific to the organisms rather than actually retrieving and characterizing the organisms themselves. For quantitation of sulfate reducing genes using qPCR, we constructed a plasmid (a piece of DNA) containing portions of two genes (known as dsrA and dsrB) that are directly involved with sulfate reduction and unique to sulfate reducing microorganisms. Using the plasmid as well as DNA from other microorganisms known to be sulfate reducers or non-sulfate reducers, we developed qPCR protocols and showed the assay’s specificity to sulfate reducers and that a qPCR standard curve using the plasmid was linear over >5 orders of magnitude. As a first test

Nitrous oxide emissions at low temperatures

International Nuclear Information System (INIS)

Martikainen, P.J.

2002-01-01

Microbial processes in soil are generally stimulated by temperature, but at low temperatures there are anomalies in the response of microbial activities. Soil physical-chemical characteristics allow existence of unfrozen water in soil also at temperatures below zero. Therefore, some microbial activities, including those responsible for nitrous oxide (N 2 0) production, can take place even in 'frozen' soil. Nitrous oxide emissions during winter are important even in boreal regions where they can account for more than 50% of the annual emissions. Snow pack therefore has great importance for N 2 0 emissions, as it insulates soil from the air allowing higher temperatures in soil than in air, and possible changes in snoav cover as a result of global warming would thus affect the N 2 0 emission from northern soils. Freezing-thawing cycles highly enhance N 2 0 emissions from soil, probably because microbial nutrients, released from disturbed soil aggregates and lysed microbial cells, support microbial N 2 0 production. However, the overall interactions between soil physics, chemistry, microbiology and N 2 0 production at low temperatures, including effects of freezing-thawing cycles, are still poorly known. (au)

Microbial biomass dynamics dominate N cycle responses to warming in a sub-arctic peatland

Science.gov (United States)

Weedon, J. T.; Aerts, R.; Kowalchuk, G. K.; van Bodegom, P. M.

2012-04-01

The balance of primary production and decomposition in sub-arctic peatlands may shift with climate change. Nitrogen availability will modulate this shift, but little is known about the drivers of soil nitrogen dynamics in these environments, and how they are influenced by rising soil temperatures. We used a long-term open top chamber warming experiment in Abisko, Sweden, to test for the interactive effects of spring warming, summer warming and winter snow addition on soil organic and inorganic nitrogen fluxes, potential activities of carbon and nitrogen cycle enzymes, and the structure of the soil-borne microbial communities. Summer warming increased the flux of soil organic nitrogen over the growing season, while simultaneously causing a seasonal decrease in microbial biomass, suggesting that N flux is driven by large late-season dieback of microbes. This change in N cycle dynamics was not reflected in any of the measured potential enzyme activities. Moreover, the soil microbial community structure was stable across treatments, suggesting non-specific microbial dieback. To further test whether the observed patterns were driven by direct temperature effects or indirect effects (via microbial biomass dynamics), we conducted follow-up controlled experiments in soil mesocosms. Experimental additions of dead microbial cells had stronger effects on N pool sizes and enzyme activities than either plant litter addition or a 5 °C alteration in incubation temperatures. Peat respiration was positively affected by both substrate addition and higher incubation temperatures, but the temperature-only effect was not sufficient to account for the increases in respiration observed in previous field experiments. We conclude that warming effects on peatland N cycling (and to some extent C cycling) are dominated by indirect effects, acting through alterations to the seasonal flux of microbe-derived organic matter. We propose that climate change models of soil carbon and nitrogen

Microbial ecology in a future climate: effects of temperature and moisture on microbial communities of two boreal fens.

Science.gov (United States)

Peltoniemi, Krista; Laiho, Raija; Juottonen, Heli; Kiikkilä, Oili; Mäkiranta, Päivi; Minkkinen, Kari; Pennanen, Taina; Penttilä, Timo; Sarjala, Tytti; Tuittila, Eeva-Stiina; Tuomivirta, Tero; Fritze, Hannu

2015-07-01

Impacts of warming with open-top chambers on microbial communities in wet conditions and in conditions resulting from moderate water-level drawdown (WLD) were studied across 0-50 cm depth in northern and southern boreal sedge fens. Warming alone decreased microbial biomass especially in the northern fen. Impact of warming on microbial PLFA and fungal ITS composition was more obvious in the northern fen and linked to moisture regime and sample depth. Fungal-specific PLFA increased in the surface peat in the drier regime and decreased in layers below 10 cm in the wet regime after warming. OTUs representing Tomentella and Lactarius were observed in drier regime and Mortierella in wet regime after warming in the northern fen. The ectomycorrhizal fungi responded only to WLD. Interestingly, warming together with WLD decreased archaeal 16S rRNA copy numbers in general, and fungal ITS copy numbers in the northern fen. Expectedly, many results indicated that microbial response on warming may be linked to the moisture regime. Results indicated that microbial community in the northern fen representing Arctic soils would be more sensitive to environmental changes. The response to future climate change clearly may vary even within a habitat type, exemplified here by boreal sedge fen. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Response of soil microbial activities and microbial community structure to vanadium stress.

Science.gov (United States)

Xiao, Xi-Yuan; Wang, Ming-Wei; Zhu, Hui-Wen; Guo, Zhao-Hui; Han, Xiao-Qing; Zeng, Peng

2017-08-01

High levels of vanadium (V) have long-term, hazardous impacts on soil ecosystems and biological processes. In the present study, the effects of V on soil enzymatic activities, basal respiration (BR), microbial biomass carbon (MBC), and the microbial community structure were investigated through 12-week greenhouse incubation experiments. The results showed that V content affected soil dehydrogenase activity (DHA), BR, and MBC, while urease activity (UA) was less sensitive to V stress. The average median effective concentration (EC 50 ) thresholds of V were predicted using a log-logistic dose-response model, and they were 362mgV/kg soil for BR and 417mgV/kg soil for DHA. BR and DHA were more sensitive to V addition and could be used as biological indicators for soil V pollution. According to a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis, the structural diversity of the microbial community decreased for soil V contents ranged between 254 and 1104mg/kg after 1 week of incubation. As the incubation time increased, the diversity of the soil microbial community structure increased for V contents ranged between 354 and 1104mg/kg, indicating that some new V-tolerant bacterial species might have replicated under these conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

Molecular analysis of the microbial community structures in water-flooding petroleum reservoirs with different temperatures

Science.gov (United States)

Wang, L.-Y.; Duan, R.-Y.; Liu, J.-F.; Yang, S.-Z.; Gu, J.-D.; Mu, B.-Z.

2012-04-01

Temperature is one of the most important environmental factors regulating the activity and determining the composition of the microbial community. Analysis of microbial communities from six water-flooding petroleum reservoirs at temperatures from 20 to 63 °C by 16S rRNA gene clone libraries indicates the presence of physiologically diverse and temperature-dependent microorganisms in these subterrestrial ecosystems. In high-temperature petroleum reservoirs, most of the archaeal sequences belong to the thermophilic archaea including the genera Thermococcus, Methanothermobacter and Thermoplasmatales, most of the bacterial sequences belong to the phyla Firmicutes, Thermotogae and Thermodesulfobacteria; in low-temperature petroleum reservoirs, most of the archaeal sequences are affiliated with the genera Methanobacterium, Methanoculleus and Methanocalculus, most of the bacterial sequences to the phyla Proteobacteria, Bacteroidetes and Actinobacteria. Canonical correspondence analysis (CCA) revealed that temperature, mineralization, ionic type as well as volatile fatty acids showed correlation with the microbial community structures. These organisms may be adapted to the environmental conditions of these petroleum reservoirs over geologic time by metabolizing buried organic matter from the original deep subsurface environment and became the common inhabitants in subsurface environments.

Comparison of Two Mechanistic Microbial Growth Models to Estimate Shelf Life of Perishable Food Package under Dynamic Temperature Conditions

Directory of Open Access Journals (Sweden)

Dong Sun Lee

2014-01-01

Full Text Available Two mechanistic microbial growth models (Huang’s model and model of Baranyi and Roberts given in differential and integrated equation forms were compared in predicting the microbial growth and shelf life under dynamic temperature storage and distribution conditions. Literatures consistently reporting the microbial growth data under constant and changing temperature conditions were selected to obtain the primary model parameters, set up the secondary models, and apply them to predict the microbial growth and shelf life under fluctuating temperatures. When evaluated by general estimation behavior, bias factor, accuracy factor, and root-mean-square error, Huang’s model was comparable to Baranyi and Roberts’ model in the capability to estimate microbial growth under dynamic temperature conditions. Its simple form of single differential equation incorporating directly the growth rate and lag time may work as an advantage to be used in online shelf life estimation by using the electronic device.

2012 Gordon Research Conference on Microbial Stress Response, Schedule and Speaker/Poster Program

Energy Technology Data Exchange (ETDEWEB)

Donohue, Timothy J. [Univ. of Wisconsin, Madison, WI (United States)

2012-07-20

The Gordon Research Conference on Microbial Stress Response was held at Mount Holyoke College, South Hadley, Massachusetts, July 15-20, 2012. The Conference was well-attended with 180 participants. The 2012 Microbial Stress Responses Gordon Research Conference will provide a forum for the open reporting of recent discoveries on the diverse mechanisms employed by microbes to respond to stress. Approaches range from analysis at the molecular level (how are signals perceived and transmitted to change gene expression or function) to cellular and microbial community responses. Attached is a copy of the formal schedule and speaker program and the poster program.

Investigating the legacy effect of drought on microbial responses to drying and rewetting along a Texan precipitation gradient

Science.gov (United States)

Hicks, Lettice; Leizeaga, Ainara; Hawkes, Christine; Rousk, Johannes

2017-04-01

Hydrological regimes will intensify due to climate change, thus increasing the duration and intensity of drought and rainfall events. Rewetting of dry soil is known to stimulate dramatic CO2 releases. A clear understanding of the mechanisms that determine the dynamics of CO2 loss upon rewetting is therefore required to characterise ecosystem C-budgets and predict responses to climate change. Laboratory studies have identified two distinct responses upon rewetting; bacterial growth either increases linearly immediately, with maximal respiration also occurring immediately and decreasing exponentially with time ("Type 1"), or bacterial growth increases exponentially after a period of near-zero growth, with a sustained period of elevated respiration, sometimes followed by a secondary increase in respiration coinciding with the onset of bacterial growth ("Type 2"). A shift from a Type 1 to a Type 2 response has been observed with increasing duration and intensity of drying prior to rewetting. The size of the surviving microbial community after drying, relative to resources available after rewetting, is suggested to dictate whether a Type 1 or 2 response occurs, with more 'harsh' (i.e. longer or more severe) drying reducing microbial biomass such that carbon available upon rewetting is sufficient to support exponential growth (leading to Type 2 response). However, this is yet to be tested in intact ecosystems. We investigated the legacy of drought on microbial responses to drying and rewetting using grassland soils from a natural precipitation gradient in Texas. Mean annual precipitation spanned a 500 mm range (400-900 mm year-1) across the 400 km gradient, while mean annual temperature was constant. Soil properties (pH, SOM) did not vary systematically across the gradient, with differences reflecting land-use history rather than rainfall. Air dried soils from 18 sites were rewetted to 50 % water holding capacity with bacterial growth, fungal growth and respiration

New insights into microbial responses to oil spills from the Deepwater Horizon incident

Energy Technology Data Exchange (ETDEWEB)

Mason, O.U.; Hazen, T.C.

2011-06-15

On April 20, 2010, a catastrophic eruption of methane caused the Deepwater Horizon exploratory drill rig drilling the Macondo Well in Mississippi Canyon Block 252 (MC252) to explode. The Deepwater Horizon oil spill was unprecendeted for several reasons: the volume of oil released; the spill duration; the well depth; the distance from the shore-line (77 km or about 50 miles); the type of oil (light crude); and the injection of dispersant directly at the wellhead. This study clearly demonstrated that there was a profound and significant response by certain members of the in situ microbial community in the deep-sea in the Gulf of Mexico. In particular putative hydrocarbon degrading Bacteria appeared to bloom in response to the Deepwater Horizon oil spill, even though the temperature at these depths is never >5 C. As the plume aged the shifts in the microbial community on a temporal scale suggested that different, yet metabolically important members of the community were able to respond to a myriad of plume constituents, e.g. shifting from propane/ethane to alkanes and finally to methane. Thus, the biodegradation of hydrocarbons in the plume by Bacteria was a highly significant process in the natural attenuation of many compounds released during the Deepwater Horizon oil spill.

Augmenting Plant Immune Responses and Biological Control by Microbial Determinants

Directory of Open Access Journals (Sweden)

Sang Moo Lee

2015-09-01

Full Text Available Plant have developed sophisticated defence mechanisms against microbial pathogens. The recent accumulated information allow us to understand the nature of plant immune responses followed by recognition of microbial factors/determinants through cutting-edge genomics and multi-omics techniques. However, the practical approaches to sustain plant health using enhancement of plant immunity is yet to be fully appreciated. Here, we overviewed the general concept and representative examples on the plant immunity. The fungal, bacterial, and viral determinants that was previously reported as the triggers of plant immune responses are introduced and described as the potential protocol of biological control. Specifically, the role of chitin, glucan, lipopolysaccharides/extracellular polysaccharides, microbe/pathogen-associated molecular pattern, antibiotics, mimic-phytohormones, N-acyl homoserine lactone, harpin, vitamins, and volatile organic compounds are considered. We hope that this review stimulates scientific community and farmers to broaden their knowledge on the microbial determinant-based biological control and to apply the technology on the integrated pest management program.

Thermodynamic and Kinetic Response of Microbial Reactions to High CO2.

Science.gov (United States)

Jin, Qusheng; Kirk, Matthew F

2016-01-01

Geological carbon sequestration captures CO 2 from industrial sources and stores the CO 2 in subsurface reservoirs, a viable strategy for mitigating global climate change. In assessing the environmental impact of the strategy, a key question is how microbial reactions respond to the elevated CO 2 concentration. This study uses biogeochemical modeling to explore the influence of CO 2 on the thermodynamics and kinetics of common microbial reactions in subsurface environments, including syntrophic oxidation, iron reduction, sulfate reduction, and methanogenesis. The results show that increasing CO 2 levels decreases groundwater pH and modulates chemical speciation of weak acids in groundwater, which in turn affect microbial reactions in different ways and to different extents. Specifically, a thermodynamic analysis shows that increasing CO 2 partial pressure lowers the energy available from syntrophic oxidation and acetoclastic methanogenesis, but raises the available energy of microbial iron reduction, hydrogenotrophic sulfate reduction and methanogenesis. Kinetic modeling suggests that high CO 2 has the potential of inhibiting microbial sulfate reduction while promoting iron reduction. These results are consistent with the observations of previous laboratory and field studies, and highlight the complexity in microbiological responses to elevated CO 2 abundance, and the potential power of biogeochemical modeling in evaluating and quantifying these responses.

Thermodynamic and kinetic response of microbial reactions to high CO2

Directory of Open Access Journals (Sweden)

Qusheng Jin

2016-11-01

Full Text Available Geological carbon sequestration captures CO2 from industrial sources and stores the CO2 in subsurface reservoirs, a viable strategy for mitigating global climate change. In assessing the environmental impact of the strategy, a key question is how microbial reactions respond to the elevated CO2 concentration. This study uses biogeochemical modeling to explore the influence of CO2 on the thermodynamics and kinetics of common microbial reactions in subsurface environments, including syntrophic oxidation, iron reduction, sulfate reduction, and methanogenesis. The results show that increasing CO2 levels decreases groundwater pH and modulates chemical speciation of weak acids in groundwater, which in turn affect microbial reactions in different ways and to different extents. Specifically, a thermodynamic analysis shows that increasing CO2 partial pressure lowers the energy available from syntrophic oxidation and acetoclastic methanogenesis, but raises the available energy of microbial iron reduction, hydrogenotrophic sulfate reduction and methanogenesis. Kinetic modeling suggests that high CO2 has the potential of inhibiting microbial sulfate reduction while promoting iron reduction. These results are consistent with the observations of previous laboratory and field studies, and highlight the complexity in microbiological responses to elevated CO2 abundance, and the potential power of biogeochemical modeling in evaluating and quantifying these responses.

Impact of warm winters on microbial growth

Science.gov (United States)

Birgander, Johanna; Rousk, Johannes; Axel Olsson, Pål

2014-05-01

Growth of soil bacteria has an asymmetrical response to higher temperature with a gradual increase with increasing temperatures until an optimum after which a steep decline occurs. In laboratory studies it has been shown that by exposing a soil bacterial community to a temperature above the community's optimum temperature for two months, the bacterial community grows warm-adapted, and the optimum temperature of bacterial growth shifts towards higher temperatures. This result suggests a change in the intrinsic temperature dependence of bacterial growth, as temperature influenced the bacterial growth even though all other factors were kept constant. An intrinsic temperature dependence could be explained by either a change in the bacterial community composition, exchanging less tolerant bacteria towards more tolerant ones, or it could be due to adaptation within the bacteria present. No matter what the shift in temperature tolerance is due to, the shift could have ecosystem scale implications, as winters in northern Europe are getting warmer. To address the question of how microbes and plants are affected by warmer winters, a winter-warming experiment was established in a South Swedish grassland. Results suggest a positive response in microbial growth rate in plots where winter soil temperatures were around 6 °C above ambient. Both bacterial and fungal growth (leucine incorporation, and acetate into ergosterol incorporation, respectively) appeared stimulated, and there are two candidate explanations for these results. Either (i) warming directly influence microbial communities by modulating their temperature adaptation, or (ii) warming indirectly affected the microbial communities via temperature induced changes in bacterial growth conditions. The first explanation is in accordance with what has been shown in laboratory conditions (explained above), where the differences in the intrinsic temperature relationships were examined. To test this explanation the

High activity and low temperature optima of extracellular enzymes in Arctic sediments: implications for carbon cycling by heterotrophic microbial communities

DEFF Research Database (Denmark)

Arnosti, C.; Jørgensen, BB

2003-01-01

(chondroitin sulfate, fucoidan, xylan and pullulan) to determine the temperature-activity responses of hydrolysis of a related class of compounds. All 4 enzyme activities showed similarly low temperature optima in the range of 15 to 18degreesC. These temperature optima are considerably lower than most previous......The rate of the initial step in microbial remineralization of organic carbon, extracellular enzymatic hydrolysis, was investigated as a function of temperature in permanently cold sediments from 2 fjords on the west coast of Svalbard (Arctic Ocean). We used 4 structurally distinct polysaccharides...... reports of temperature optima for enzyme activities in marine sediments. At 0degreesC, close to the in situ temperature, these enzyme activities achieved 13 to 38% of their rates at optimum temperatures. In one experiment, sulfate reduction rates were measured in parallel with extracellular enzymatic...

Fire vs. Metal: A Laboratory Study Demonstrating Microbial Responses to Soil Disturbances

Science.gov (United States)

Stromberger, Mary E.

2005-01-01

Incubation studies are traditionally used in soil microbiology laboratory classes to demonstrate microbial respiration and N mineralization-immobilization processes. Sometimes these exercises are done to calculate a N balance in N fertilizer-amended soils. However, examining microbial responses to environmental perturbations would appeal to soil…

Seasonal variations of indoor microbial exposures and their relation to temperature, relative humidity, and air exchange rate.

Science.gov (United States)

Frankel, Mika; Bekö, Gabriel; Timm, Michael; Gustavsen, Sine; Hansen, Erik Wind; Madsen, Anne Mette

2012-12-01

Indoor microbial exposure has been related to adverse pulmonary health effects. Exposure assessment is not standardized, and various factors may affect the measured exposure. The aim of this study was to investigate the seasonal variation of selected microbial exposures and their associations with temperature, relative humidity, and air exchange rates in Danish homes. Airborne inhalable dust was sampled in five Danish homes throughout the four seasons of 1 year (indoors, n = 127; outdoors, n = 37). Measurements included culturable fungi and bacteria, endotoxin, N-acetyl-beta-d-glucosaminidase, total inflammatory potential, particles (0.75 to 15 μm), temperature, relative humidity, and air exchange rates. Significant seasonal variation was found for all indoor microbial exposures, excluding endotoxin. Indoor fungi peaked in summer (median, 235 CFU/m(3)) and were lowest in winter (median, 26 CFU/m(3)). Indoor bacteria peaked in spring (median, 2,165 CFU/m(3)) and were lowest in summer (median, 240 CFU/m(3)). Concentrations of fungi were predominately higher outdoors than indoors, whereas bacteria, endotoxin, and inhalable dust concentrations were highest indoors. Bacteria and endotoxin correlated with the mass of inhalable dust and number of particles. Temperature and air exchange rates were positively associated with fungi and N-acetyl-beta-d-glucosaminidase and negatively with bacteria and the total inflammatory potential. Although temperature, relative humidity, and air exchange rates were significantly associated with several indoor microbial exposures, they could not fully explain the observed seasonal variations when tested in a mixed statistical model. In conclusion, the season significantly affects indoor microbial exposures, which are influenced by temperature, relative humidity, and air exchange rates.

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

The influence of temperature and moisture contents regimes on the aerobic microbial activity of a biosolids composting blend.

Science.gov (United States)

Liang, C; Das, K C; McClendon, R W

2003-01-01

To understand the relationships between temperature, moisture content, and microbial activity during the composting of biosolids (municipal wastewater treatment sludge), well-controlled incubation experiments were conducted using a 2-factor factorial design with six temperatures (22, 29, 36, 43, 50, and 57 degrees C) and five moisture contents (30, 40, 50, 60, and 70%). The microbial activity was measured as O2 uptake rate (mg g(-1) h(-1)) using a computer controlled respirometer. In this study, moisture content proved to be a dominant factor impacting aerobic microbial activity of the composting blend. Fifty percent moisture content appeared to be the minimal requirement for obtaining activities greater than 1.0 mg g(-1) h(-1). Temperature was also documented to be an important factor for biosolids composting. However, its effect was less influential than moisture content. Particularly, the enhancement of composting activities induced by temperature increment could be realized by increasing moisture content alone.

Water regime history drives responses of soil Namib Desert microbial communities to wetting events

Science.gov (United States)

Frossard, Aline; Ramond, Jean-Baptiste; Seely, Mary; Cowan, Don A.

2015-07-01

Despite the dominance of microorganisms in arid soils, the structures and functional dynamics of microbial communities in hot deserts remain largely unresolved. The effects of wetting event frequency and intensity on Namib Desert microbial communities from two soils with different water-regime histories were tested over 36 days. A total of 168 soil microcosms received wetting events mimicking fog, light rain and heavy rainfall, with a parallel “dry condition” control. T-RFLP data showed that the different wetting events affected desert microbial community structures, but these effects were attenuated by the effects related to the long-term adaptation of both fungal and bacterial communities to soil origins (i.e. soil water regime histories). The intensity of the water pulses (i.e. the amount of water added) rather than the frequency of wetting events had greatest effect in shaping bacterial and fungal community structures. In contrast to microbial diversity, microbial activities (enzyme activities) showed very little response to the wetting events and were mainly driven by soil origin. This experiment clearly demonstrates the complexity of microbial community responses to wetting events in hyperarid hot desert soil ecosystems and underlines the dynamism of their indigenous microbial communities.

Ecological and soil hydraulic implications of microbial responses to stress - A modeling analysis

Science.gov (United States)

Brangarí, Albert C.; Fernàndez-Garcia, Daniel; Sanchez-Vila, Xavier; Manzoni, Stefano

2018-06-01

A better understanding of microbial dynamics in porous media may lead to improvements in the design and management of a number of technological applications, ranging from the degradation of contaminants to the optimization of agricultural systems. To this aim, there is a recognized need for predicting the proliferation of soil microbial biomass (often organized in biofilms) under different environments and stresses. We present a general multi-compartment model to account for physiological responses that have been extensively reported in the literature. The model is used as an explorative tool to elucidate the ecological and soil hydraulic consequences of microbial responses, including the production of extracellular polymeric substances (EPS), the induction of cells into dormancy, and the allocation and reuse of resources between biofilm compartments. The mechanistic model is equipped with indicators allowing the microorganisms to monitor environmental and biological factors and react according to the current stress pressures. The feedbacks of biofilm accumulation on the soil water retention are also described. Model runs simulating different degrees of substrate and water shortage show that adaptive responses to the intensity and type of stress provide a clear benefit to microbial colonies. Results also demonstrate that the model may effectively predict qualitative patterns in microbial dynamics supported by empirical evidence, thereby improving our understanding of the effects of pore-scale physiological mechanisms on the soil macroscale phenomena.

The Influence of Loading Rate and Variable Temperatures on Microbial Communities in Anaerobic Digesters

Directory of Open Access Journals (Sweden)

Richard J. Ciotola

2014-02-01

Full Text Available The relationship between seasonal temperatures, organic loading rate (OLR and the structure of archaeal communities in anaerobic digesters was investigated. Previous studies have often assessed archaeal community structure at fixed temperatures and constant OLRs, or at variable temperatures not characteristic of temperate climates. The goal of this study was to determine the maximum OLR that would maintain a balanced microbial ecosystem during operation in a variable temperature range expected in a temperate climate (27–10 °C. Four-liter laboratory digesters were operated in a semi-continuous mode using dairy cow manure as the feedstock. At OLRs of 1.8 and 0.8 kg VS/m3·day the digesters soured (pH < 6.5 as a result of a decrease in temperature. The structure of the archaeal community in the sour digesters became increasingly similar to the manure feedstock with gains in the relative abundance of hydrogenotrophic methanogens. At an OLR of 0.3 kg VS/m3·day the digesters did not sour, but the archaeal community was primarily hydrogenotrophic methanogens. Recommendations for operating an ambient temperature digester year round in a temperate climate are to reduce the OLR to at least 0.3 kg VS/m3·day in colder temperatures to prevent a shift to the microbial community associated with the sour digesters.

Soil microbial responses to climate warming in Northern Andean alpine ecosystems

Science.gov (United States)

Gallery, R. E.; Lasso, E.

2017-12-01

The historically cooler temperatures and waterlogged soils of tropical alpine grasslands (páramo) have resulted in low decomposition rates and a large buildup of organic matter, making páramo one of the most important carbon sinks in tropical biomes. The climatic factors that favored the carbon accumulation are changing, and as a result páramo could play a disproportionate role in driving climate feedbacks through increased carbon released from these large soil carbon stores. Open top chamber warming experiments were established in the Colombian Andes in 2016 to quantify the magnitude of climate change on carbon balance and identify microbial and plant traits that regulate these impacts. Two focal sites differ in mean annual temperature, precipitation, and plant community richness. Heterotrophic respiration (RH,) was measured from soil cores incubated at temperatures representing current and projected warming. The warming effect on RH was sensitive to soil moisture, which could reflect shifts in microbial community composition and/or extracellular enzyme production or efficiency as soils dry. Bacterial, archaeal, and fungal communities in ambient and warmed plots were measured through high-throughput amplicon sequencing of the 16S rRNA and ITS1 rRNA gene regions. Communities showed strong spatial structuring both within and among páramo, reflecting the topographic heterogeneity of these ecosystems. Significant differences in relative abundance of dominant microbial taxa between páramo could be largely explained by soil bulk density, water holding capacity, and non-vascular plant cover. Phototrophs common to anoxic soils (e.g., Rhodospirillaceae, Hyphomicrobiaceae) were abundant. Taxa within Euryarchaeota were recovered, suggesting methanogenesis potential. Exploration of the magnitude and temperature sensitivity of methane flux is needed in these seasonally anoxic soils whose dynamics could have significant implications for the global climate system.

Effects of diurnal temperature variation on microbial community and petroleum hydrocarbon biodegradation in contaminated soils from a sub-Arctic site.

Science.gov (United States)

Akbari, Ali; Ghoshal, Subhasis

2015-12-01

Contaminated soils are subject to diurnal and seasonal temperature variations during on-site ex-situ bioremediation processes. We assessed how diurnal temperature variations similar to that in summer at the site from which petroleum hydrocarbon-contaminated soil was collected affect the soil microbial community and the extent of biodegradation of petroleum hydrocarbons compared with constant temperature regimes. Microbial community analyses for 16S rRNA and alkB genes by pyrosequencing indicated that the microbial community for soils incubated under diurnal temperature variation from 5°C to 15°C (VART5-15) evolved similarly to that for soils incubated at constant temperature of 15°C (CST15). In contrast, under a constant temperature of 5°C (CST5), the community evolved significantly different. The extent of biodegradation of C10-C16 hydrocarbons in the VART5-15 systems was 48%, comparable with the 41% biodegradation in CST15 systems, but significantly higher than CST5 systems at 11%. The enrichment of Gammaproteobacteria was observed in the alkB gene-harbouring communities in VART5-15 and CST15 but not in CST5 systems. However, the Actinobacteria was abundant at all temperature regimes. The results suggest that changes in microbial community composition as a result of diurnal temperature variations can significantly influence petroleum hydrocarbon bioremediation performance in cold regions. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Shifts in the microbial community structure explain the response of soil respiration to land-use change but not to climate warming

DEFF Research Database (Denmark)

Nazaries, Loïc; Tottey, William; Robinson, Lucinda

2015-01-01

Soil stores more carbon (C) than plants and atmosphere combined and it is vulnerable to increased microbial respiration under projected global changes including land-use change and future climate scenarios (mainly elevated temperature). Land-use change is known to have a direct impact on soil...... of this feedback response of Rs to global change. To identify the mechanisms of Rs response to land-use change and climate warming, we first investigated Rs from different land use types. Soil respiration was estimated seasonally from four different Scottish land uses: moorland, birch woodland, grassland and pine......, estimated by Multiplex Terminal-Restriction Fragment Length Polymorphism (MT-RFLP) and 454 pyrosequencing, was significantly different under each land use type. A strong correlation of Rs with soil properties (pH, inorganic N, C:N ratio and moisture) and with microbial community structure was identified...

Biochar increases plant growth and alters microbial communities via regulating the moisture and temperature of green roof substrates.

Science.gov (United States)

Chen, Haoming; Ma, Jinyi; Wei, Jiaxing; Gong, Xin; Yu, Xichen; Guo, Hui; Zhao, Yanwen

2018-09-01

Green roofs have increasingly been designed and applied to relieve environmental problems, such as water loss, air pollution as well as heat island effect. Substrate and vegetation are important components of green roofs providing ecosystem services and benefiting the urban development. Biochar made from sewage sludge could be potentially used as the substrate amendment for green roofs, however, the effects of biochar on substrate quality and plant performance in green roofs are still unclear. We evaluated the effects of adding sludge biochar (0, 5, 10, 15 and 20%, v/v) to natural soil planted with three types of plant species (ryegrass, Sedum lineare and cucumber) on soil properties, plant growth and microbial communities in both green roof and ground ecosystems. Our results showed that sludge biochar addition significantly increased substrate moisture, adjusted substrate temperature, altered microbial community structure and increased plant growth. The application rate of 10-15% sludge biochar on the green roof exerted the most significant effects on both microbial and plant biomass by 63.9-89.6% and 54.0-54.2% respectively. Path analysis showed that biochar addition had a strong effect on microbial biomass via changing the soil air-filled porosity, soil moisture and temperature, and promoted plant growth through the positive effects on microbial biomass. These results suggest that the applications of biochar at an appropriate rate can significantly alter plant growth and microbial community structure, and increase the ecological benefits of green roofs via exerting effects on the moisture, temperature and nutrients of roof substrates. Copyright © 2018 Elsevier B.V. All rights reserved.

Impact of temperature and time storage on the microbial detection of oral samples by Checkerboard DNA-DNA hybridization method.

Science.gov (United States)

do Nascimento, Cássio; dos Santos, Janine Navarro; Pedrazzi, Vinícius; Pita, Murillo Sucena; Monesi, Nadia; Ribeiro, Ricardo Faria; de Albuquerque, Rubens Ferreira

2014-01-01

Molecular diagnosis methods have been largely used in epidemiological or clinical studies to detect and quantify microbial species that may colonize the oral cavity in healthy or disease. The preservation of genetic material from samples remains the major challenge to ensure the feasibility of these methodologies. Long-term storage may compromise the final result. The aim of this study was to evaluate the effect of temperature and time storage on the microbial detection of oral samples by Checkerboard DNA-DNA hybridization. Saliva and supragingival biofilm were taken from 10 healthy subjects, aliquoted (n=364) and processed according to proposed protocols: immediate processing and processed after 2 or 4 weeks, and 6 or 12 months of storage at 4°C, -20°C and -80°C. Either total or individual microbial counts were recorded in lower values for samples processed after 12 months of storage, irrespective of temperatures tested. Samples stored up to 6 months at cold temperatures showed similar counts to those immediately processed. The microbial incidence was also significantly reduced in samples stored during 12 months in all temperatures. Temperature and time of oral samples storage have relevant impact in the detection and quantification of bacterial and fungal species by Checkerboard DNA-DNA hybridization method. Samples should be processed immediately after collection or up to 6 months if conserved at cold temperatures to avoid false-negative results. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microbial Community Dynamics from Permafrost Across the Pleistocene-Holocene Boundary and Response to Abrupt Climate Change

Science.gov (United States)

Hammad, A.; Mahony, M.; Froese, D. G.; Lanoil, B. D.

2014-12-01

Earth is currently undergoing rapid warming similar to that observed about 10,000 years ago at the end of the Pleistocene. We know a considerable amount about the adaptations and extinctions of mammals and plants at the Pleistocene/Holocene (P/H) boundary, but relatively little about changes at the microbial level. Due to permafrost soils' freezing anoxic conditions, they act as microbial diversity archives allowing us to determine how microbial communities adapted to the abrupt warming at the end of P. Since microbial community composition only helps differentiate viable and extant microorganisms in frozen permafrost, microbial activity in thawing permafrost must be investigated to provide a clear understanding of microbial response to climate change. Current increased temperatures will result in warming and potential thaw of permafrost and release of stored organic carbon, freeing it for microbial utilization; turning permafrost into a carbon source. Studying permafrost viable microbial communities' diversity and activity will provide a better understanding of how these microorganisms respond to soil edaphic variability due to climate change across the P/H boundary, providing insight into the changes that the soil community is currently undergoing in this modern era of rapid climate change. Modern soil, H and P permafrost cores were collected from Lucky Lady II site outside Dawson City, Yukon. 16S rRNA high throughput sequencing of permafrost DNA showed the same trends for total and viable community richness and diversity with both decreasing with permafrost depth and only the richness increasing in mid and early P. The modern, H and P soils had 50.9, 33.9, and 27.3% unique viable species and only 14% of the total number of viable species were shared by all soils. Gas flux measurements of thawed permafrost showed metabolic activity in modern and permafrost soils, aerobic CH­­4 consumption in modern, some H and P soils, and anaerobic CH­­4 production in one H

Biodegradation of n-alkanes on oil-seawater interfaces at different temperatures and microbial communities associated with the degradation.

Science.gov (United States)

Lofthus, Synnøve; Netzer, Roman; Lewin, Anna S; Heggeset, Tonje M B; Haugen, Tone; Brakstad, Odd Gunnar

2018-04-01

Oil biodegradation studies have mainly focused on microbial processes in dispersions, not specifically on the interfaces between the oil and the seawater in the dispersions. In this study, a hydrophobic adsorbent system, consisting of Fluortex fabrics, was used to investigate biodegradation of n-alkanes and microbial communities on oil-seawater interfaces in natural non-amended seawater. The study was performed over a temperature range from 0 to 20 °C, to determine how temperature affected biodegradation at the oil-seawater interfaces. Biodegradation of n-alkanes were influenced both by seawater temperature and chain-length. Biotransformation rates of n-alkanes decreased by reduced seawater temperature. Low rate coefficients at a seawater temperature of 0 °C were probably associated with changes in physical-chemical properties of alkanes. The primary bacterial colonization of the interfaces was predominated by the family Oceanospirillaceae at all temperatures, demonstrating the wide temperature range of these hydrocarbonoclastic bacteria. The mesophilic genus Oleibacter was predominant at the seawater temperature of 20 °C, and the psychrophilic genus Oleispira at 5 and 0 °C. Upon completion of n-alkane biotransformation, other oil-degrading and heterotrophic bacteria became abundant, including Piscirickettsiaceae (Cycloclasticus), Colwelliaceae (Colwellia), Altermonadaceae (Altermonas), and Rhodobacteraceae. This is one of a few studies that describe the biodegradation of oil, and the microbial communities associated with the degradation, directly at the oil-seawater interfaces over a large temperature interval.

Effect of temperature and cycle length on microbial competition in PHB-producing sequencing batch reactor

NARCIS (Netherlands)

Jiang, Y.; Marang, L.; Kleerebezem, R.; Muyzer, G.; van Loosdrecht, M.C.M.

2011-01-01

The impact of temperature and cycle length on microbial competition between polyhydroxybutyrate (PHB)-producing populations enriched in feast-famine sequencing batch reactors (SBRs) was investigated at temperatures of 20 °C and 30 °C, and in a cycle length range of 1-18 h. In this study, the

Temperature response of denitrification rate and greenhouse gas production in agricultural river marginal wetland soils.

Science.gov (United States)

Bonnett, S A F; Blackwell, M S A; Leah, R; Cook, V; O'Connor, M; Maltby, E

2013-05-01

Soils are predicted to exhibit significant feedback to global warming via the temperature response of greenhouse gas (GHG) production. However, the temperature response of hydromorphic wetland soils is complicated by confounding factors such as oxygen (O2 ), nitrate (NO3-) and soil carbon (C). We examined the effect of a temperature gradient (2-25 °C) on denitrification rates and net nitrous oxide (N2 O), methane (CH4 ) production and heterotrophic respiration in mineral (Eutric cambisol and Fluvisol) and organic (Histosol) soil types in a river marginal landscape of the Tamar catchment, Devon, UK, under non-flooded and flooded with enriched NO3- conditions. It was hypothesized that the temperature response is dependent on interactions with NO3--enriched flooding, and the physicochemical conditions of these soil types. Denitrification rate (mean, 746 ± 97.3 μg m(-2)  h(-1) ), net N2 O production (mean, 180 ± 26.6 μg m(-2)  h(-1) ) and net CH4 production (mean, 1065 ± 183 μg m(-2)  h(-1) ) were highest in the organic Histosol, with higher organic matter, ammonium and moisture, and lower NO3- concentrations. Heterotrophic respiration (mean, 127 ± 4.6 mg m(-2)  h(-1) ) was not significantly different between soil types and dominated total GHG (CO2 eq) production in all soil types. Generally, the temperature responses of denitrification rate and net N2 O production were exponential, whilst net CH4 production was unresponsive, possibly due to substrate limitation, and heterotrophic respiration was exponential but limited in summer at higher temperatures. Flooding with NO3- increased denitrification rate, net N2 O production and heterotrophic respiration, but a reduction in net CH4 production suggests inhibition of methanogenesis by NO3- or N2 O produced from denitrification. Implications for management and policy are that warming and flood events may promote microbial interactions in soil between distinct microbial communities and increase

Linking temperature sensitivity of soil organic matter decomposition to its molecular structure, accessibility, and microbial physiology.

Science.gov (United States)

Wagai, Rota; Kishimoto-Mo, Ayaka W; Yonemura, Seiichiro; Shirato, Yasuhito; Hiradate, Syuntaro; Yagasaki, Yasumi

2013-04-01

Temperature sensitivity of soil organic matter (SOM) decomposition may have a significant impact on global warming. Enzyme-kinetic hypothesis suggests that decomposition of low-quality substrate (recalcitrant molecular structure) requires higher activation energy and thus has greater temperature sensitivity than that of high-quality, labile substrate. Supporting evidence, however, relies largely on indirect indices of substrate quality. Furthermore, the enzyme-substrate reactions that drive decomposition may be regulated by microbial physiology and/or constrained by protective effects of soil mineral matrix. We thus tested the kinetic hypothesis by directly assessing the carbon molecular structure of low-density fraction (LF) which represents readily accessible, mineral-free SOM pool. Using five mineral soil samples of contrasting SOM concentrations, we conducted 30-days incubations (15, 25, and 35 °C) to measure microbial respiration and quantified easily soluble C as well as microbial biomass C pools before and after the incubations. Carbon structure of LFs (soil was measured by solid-state (13) C-NMR. Decomposition Q10 was significantly correlated with the abundance of aromatic plus alkyl-C relative to O-alkyl-C groups in LFs but not in bulk soil fraction or with the indirect C quality indices based on microbial respiration or biomass. The warming did not significantly change the concentration of biomass C or the three types of soluble C despite two- to three-fold increase in respiration. Thus, enhanced microbial maintenance respiration (reduced C-use efficiency) especially in the soils rich in recalcitrant LF might lead to the apparent equilibrium between SOM solubilization and microbial C uptake. Our results showed physical fractionation coupled with direct assessment of molecular structure as an effective approach and supported the enzyme-kinetic interpretation of widely observed C quality-temperature relationship for short-term decomposition. Factors

The microbial community in a high-temperature enhanced biological phosphorus removal (EBPR process

Directory of Open Access Journals (Sweden)

Ying Hui Ong

2016-01-01

Full Text Available An enhanced biological phosphorus removal (EBPR process operated at a relatively high temperature, 28 °C, removed 85% carbon and 99% phosphorus from wastewater over a period of two years. This study investigated its microbial community through fluorescent in situ hybridization (FISH and clone library generation. Through FISH, considerably more Candidatus “Accumulibacter phosphatis” (Accumulibacter-polyphosphate accumulating organisms (PAOs than Candidatus ‘Competibacter phosphatis’ (Competibacter-glycogen accumulating organisms were detected in the reactor, at 36 and 7% of total bacterial population, respectively. A low ratio of Glycogen/Volatile Fatty Acid of 0.69 further indicated the dominance of PAOs in the reactor. From clone library generated, 26 operational taxonomy units were retrieved from the sludge and a diverse population was shown, comprising Proteobacteria (69.6%, Actinobacteria (13.7%, Bacteroidetes (9.8%, Firmicutes (2.94%, Planctomycetes (1.96%, and Acidobacteria (1.47%. Accumulibacter are the only recognized PAOs revealed by the clone library. Both the clone library and FISH results strongly suggest that Accumulibacter are the major PAOs responsible for the phosphorus removal in this long-term EBPR at relatively high temperature.

Rapid Response of Eastern Mediterranean Deep Sea Microbial Communities to Oil

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiang; Techtmann, Stephen M.; Woo, Hannah L.; Ning, Daliang; Fortney, Julian L.; Hazen, Terry C.

2017-07-18

Deep marine oil spills like the Deepwater Horizon (DWH) in the Gulf of Mexico have the potential to drastically impact marine systems. Crude oil contamination in marine systems remains a concern, especially for countries around the Mediterranean Sea with off shore oil production. The goal of this study was to investigate the response of indigenous microbial communities to crude oil in the deep Eastern Mediterranean Sea (E. Med.) water column and to minimize potential bias associated with storage and shifts in microbial community structure from sample storage. 16S rRNA amplicon sequencing was combined with GeoChip metagenomic analysis to monitor the microbial community changes to the crude oil and dispersant in on-ship microcosms set up immediately after water collection. After 3 days of incubation at 14 °C, the microbial communities from two different water depths: 824 m and 1210 m became dominated by well-known oil degrading bacteria. The archaeal population and the overall microbial community diversity drastically decreased. Similarly, GeoChip metagenomic analysis revealed a tremendous enrichment of genes related to oil biodegradation, which was consistent with the results from the DWH oil spill. These results highlight a rapid microbial adaption to oil contamination in the deep E. Med., and indicate strong oil biodegradation potentia

Response of soil microbial communities and microbial interactions to long-term heavy metal contamination.

Science.gov (United States)

Li, Xiaoqi; Meng, Delong; Li, Juan; Yin, Huaqun; Liu, Hongwei; Liu, Xueduan; Cheng, Cheng; Xiao, Yunhua; Liu, Zhenghua; Yan, Mingli

2017-12-01

Due to the persistence of metals in the ecosystem and their threat to all living organisms, effects of heavy metal on soil microbial communities were widely studied. However, little was known about the interactions among microorganisms in heavy metal-contaminated soils. In the present study, microbial communities in Non (CON), moderately (CL) and severely (CH) contaminated soils were investigated through high-throughput Illumina sequencing of 16s rRNA gene amplicons, and networks were constructed to show the interactions among microbes. Results showed that the microbial community composition was significantly, while the microbial diversity was not significantly affected by heavy metal contamination. Bacteria showed various response to heavy metals. Bacteria that positively correlated with Cd, e.g. Acidobacteria_Gp and Proteobacteria_thiobacillus, had more links between nodes and more positive interactions among microbes in CL- and CH-networks, while bacteria that negatively correlated with Cd, e.g. Longilinea, Gp2 and Gp4 had fewer network links and more negative interactions in CL and CH-networks. Unlike bacteria, members of the archaeal domain, i.e. phyla Crenarchaeota and Euryarchaeota, class Thermoprotei and order Thermoplasmatales showed only positive correlation with Cd and had more network interactions in CH-networks. The present study indicated that (i) the microbial community composition, as well as network interactions was shift to strengthen adaptability of microorganisms to heavy metal contamination, (ii) archaea were resistant to heavy metal contamination and may contribute to the adaption to heavy metals. It was proposed that the contribution might be achieved either by improving environment conditions or by cooperative interactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

An Evaluation of Subsurface Microbial Activity Conditional to Subsurface Temperature, Porosity, and Permeability at North American Carbon Sequestration Sites

Energy Technology Data Exchange (ETDEWEB)

Wilson, B. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Mordensky, S. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Verba, Circe [National Energy Technology Lab. (NETL), Albany, OR (United States); Rabjohns, K. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Colwell, F. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences

2016-06-21

Several nations, including the United States, recognize global climate change as a force transforming the global ecosphere. Carbon dioxide (CO₂) is a greenhouse gas that contributes to the evolving climate. Reduction of atmospheric CO₂ levels is a goal for many nations and carbon sequestration which traps CO₂ in the Earth’s subsurface is one method to reduce atmospheric CO₂ levels. Among the variables that must be considered in developing this technology to a national scale is microbial activity. Microbial activity or biomass can change rock permeability, alter artificial seals around boreholes, and play a key role in biogeochemistry and accordingly may determine how CO₂ is sequestered underground. Certain physical parameters of a reservoir found in literature (e.g., temperature, porosity, and permeability) may indicate whether a reservoir can host microbial communities. In order to estimate which subsurface formations may host microbes, this report examines the subsurface temperature, porosity, and permeability of underground rock formations that have high potential to be targeted for CO₂ sequestration. Of the 268 North American wellbore locations from the National Carbon Sequestration Database (NATCARB; National Energy and Technology Laboratory, 2015) and 35 sites from Nelson and Kibler (2003), 96 sequestration sites contain temperature data. Of these 96 sites, 36 sites have temperatures that would be favorable for microbial survival, 48 sites have mixed conditions for supporting microbial populations, and 11 sites would appear to be unfavorable to support microbial populations. Future studies of microbe viability would benefit from a larger database with more formation parameters (e.g. mineralogy, structure, and groundwater chemistry), which would help to increase understanding of where CO₂ sequestration could be most efficiently implemented.

Ready or Not: Microbial Adaptive Responses in Dynamic Symbiosis Environments.

Science.gov (United States)

Cao, Mengyi; Goodrich-Blair, Heidi

2017-08-01

In mutually beneficial and pathogenic symbiotic associations, microbes must adapt to the host environment for optimal fitness. Both within an individual host and during transmission between hosts, microbes are exposed to temporal and spatial variation in environmental conditions. The phenomenon of phenotypic variation, in which different subpopulations of cells express distinctive and potentially adaptive characteristics, can contribute to microbial adaptation to a lifestyle that includes rapidly changing environments. The environments experienced by a symbiotic microbe during its life history can be erratic or predictable, and each can impact the evolution of adaptive responses. In particular, the predictability of a rhythmic or cyclical series of environments may promote the evolution of signal transduction cascades that allow preadaptive responses to environments that are likely to be encountered in the future, a phenomenon known as adaptive prediction. In this review, we summarize environmental variations known to occur in some well-studied models of symbiosis and how these may contribute to the evolution of microbial population heterogeneity and anticipatory behavior. We provide details about the symbiosis between Xenorhabdus bacteria and Steinernema nematodes as a model to investigate the concept of environmental adaptation and adaptive prediction in a microbial symbiosis. Copyright © 2017 American Society for Microbiology.

Effect of temperature and cycle length on microbial competition in PHB-producing sequencing batch reactor.

Science.gov (United States)

Jiang, Yang; Marang, Leonie; Kleerebezem, Robbert; Muyzer, Gerard; van Loosdrecht, Mark C M

2011-05-01

The impact of temperature and cycle length on microbial competition between polyhydroxybutyrate (PHB)-producing populations enriched in feast-famine sequencing batch reactors (SBRs) was investigated at temperatures of 20 °C and 30 °C, and in a cycle length range of 1-18 h. In this study, the microbial community structure of the PHB-producing enrichments was found to be strongly dependent on temperature, but not on cycle length. Zoogloea and Plasticicumulans acidivorans dominated the SBRs operated at 20 °C and 30 °C, respectively. Both enrichments accumulated PHB more than 75% of cell dry weight. Short-term temperature change experiments revealed that P. acidivorans was more temperature sensitive as compared with Zoogloea. This is particularly true for the PHB degradation, resulting in incomplete PHB degradation in P. acidivorans at 20 °C. Incomplete PHB degradation limited biomass growth and allowed Zoogloea to outcompete P. acidivorans. The PHB content at the end of the feast phase correlated well with the cycle length at a constant solid retention time (SRT). These results suggest that to establish enrichment with the capacity to store a high fraction of PHB, the number of cycles per SRT should be minimized independent of the temperature.

Actual measurement, hygrothermal response experiment and growth prediction analysis of microbial contamination of central air conditioning system in Dalian, China.

Science.gov (United States)

Lv, Yang; Hu, Guangyao; Wang, Chunyang; Yuan, Wenjie; Wei, Shanshan; Gao, Jiaoqi; Wang, Boyuan; Song, Fangchao

2017-04-03

The microbial contamination of central air conditioning system is one of the important factors that affect the indoor air quality. Actual measurement and analysis were carried out on microbial contamination in central air conditioning system at a venue in Dalian, China. Illumina miseq method was used and three fungal samples of two units were analysed by high throughput sequencing. Results showed that the predominant fungus in air conditioning unit A and B were Candida spp. and Cladosporium spp., and two fungus were further used in the hygrothermal response experiment. Based on the data of Cladosporium in hygrothermal response experiment, this paper used the logistic equation and the Gompertz equation to fit the growth predictive model of Cladosporium genera in different temperature and relative humidity conditions, and the square root model was fitted based on the two environmental factors. In addition, the models were carried on the analysis to verify the accuracy and feasibility of the established model equation.

Temperature regulates deterministic processes and the succession of microbial interactions in anaerobic digestion process

Czech Academy of Sciences Publication Activity Database

Lin, Qiang; De Vrieze, J.; Li, Ch.; Li, J.; Li, J.; Yao, M.; Heděnec, Petr; Li, H.; Li, T.; Rui, J.; Frouz, Jan; Li, X.

2017-01-01

Roč. 123, October (2017), s. 134-143 ISSN 0043-1354 Institutional support: RVO:60077344 Keywords : anaerobic digestion * deterministic process * microbial interactions * modularity * temperature gradient Subject RIV: DJ - Water Pollution ; Quality OBOR OECD: Water resources Impact factor: 6.942, year: 2016

Microbially induced corrosion of carbon steel in deep groundwater environment

Directory of Open Access Journals (Sweden)

Pauliina eRajala

2015-07-01

Full Text Available The metallic low and intermediate level radioactive waste generally consists of carbon steel and stainless steels. The corrosion rate of carbon steel in deep groundwater is typically low, unless the water is very acidic or microbial activity in the environment is high. Therefore, the assessment of microbially induced corrosion of carbon steel in deep bedrock environment has become important for evaluating the safety of disposal of radioactive waste. Here we studied the corrosion inducing ability of indigenous microbial community from a deep bedrock aquifer. Carbon steel coupons were exposed to anoxic groundwater from repository site 100 m depth (Olkiluoto, Finland for periods of three and eight months. The experiments were conducted at both in situ temperature and room temperature to investigate the response of microbial population to elevated temperature. Our results demonstrate that microorganisms from the deep bedrock aquifer benefit from carbon steel introduced to the nutrient poor anoxic deep groundwater environment. In the groundwater incubated with carbon steel the planktonic microbial community was more diverse and 100-fold more abundant compared to the environment without carbon steel. The betaproteobacteria were the most dominant bacterial class in all samples where carbon steel was present, whereas in groundwater incubated without carbon steel the microbial community had clearly less diversity. Microorganisms induced pitting corrosion and were found to cluster inside the corrosion pits. Temperature had an effect on the species composition of microbial community and also affected the corrosion deposits layer formed on the surface of carbon steel.

The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China

Science.gov (United States)

Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

2015-11-01

Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50-90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3-74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60-80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6-90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2- per cell d-1 with a temperature change from 50 to 70 °C.

The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China.

Science.gov (United States)

Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

2015-11-26

Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50-90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3-74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60-80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6-90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2(-) per cell d(-1) with a temperature change from 50 to 70 °C.

Development of a High Temperature Microbial Fermentation Processfor Butanol Production

Energy Technology Data Exchange (ETDEWEB)

Jeor, Jeffery D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Reed, David W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Daubaras, Dayna L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Vicki S. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-06-01

Transforming renewable biomass into cost competitive high-performance biofuels and bioproducts is key to US energy security. Butanol production by microbial fermentation and chemical conversion to polyolefins, elastomers, drop-in jet or diesel fuel, and other chemicals is a promising solution. A high temperature fermentation process can facilitate butanol recovery up to 40%, by using gas stripping. Other benefits of fermentation at high temperatures are optimal hydrolysis rates in the saccharification of biomass which leads to maximized butanol production, decrease in energy costs associated with reactor cooling and capital cost associated with reactor design, and a decrease in contamination and cost for maintaining a sterile environment. Butanol stripping at elevated temperatures gives higher butanol production through constant removal and continuous fermentation. We describe methods used in an attempt to genetically prepare Geobacillus caldoxylosiliticus for insertion of a butanol pathway. Methods used were electroporation of electrocompetent cells, ternary conjugation with E. coli, and protoplast fusion.

Development of a High Temperature Microbial Fermentation Processfor Butanol Production

International Nuclear Information System (INIS)

Jeor, Jeffery D.; Reed, David W.; Daubaras, Dayna L.; Thompson, Vicki S.

2016-01-01

Transforming renewable biomass into cost competitive high-performance biofuels and bioproducts is key to US energy security. Butanol production by microbial fermentation and chemical conversion to polyolefins, elastomers, drop-in jet or diesel fuel, and other chemicals is a promising solution. A high temperature fermentation process can facilitate butanol recovery up to 40%, by using gas stripping. Other benefits of fermentation at high temperatures are optimal hydrolysis rates in the saccharification of biomass which leads to maximized butanol production, decrease in energy costs associated with reactor cooling and capital cost associated with reactor design, and a decrease in contamination and cost for maintaining a sterile environment. Butanol stripping at elevated temperatures gives higher butanol production through constant removal and continuous fermentation. We describe methods used in an attempt to genetically prepare Geobacillus caldoxylosiliticus for insertion of a butanol pathway. Methods used were electroporation of electrocompetent cells, ternary conjugation with E. coli, and protoplast fusion.

Investigation on the response of anaerobic membrane bioreactor to temperature decrease from 25°C to 10°C in sewage treatment.

Science.gov (United States)

Watanabe, Ryoya; Nie, Yulun; Wakahara, Shinichiro; Komori, Daisuke; Li, Yu-You

2017-11-01

Anaerobic membrane bioreactor (AnMBR) for sewage treatment was operated for 650days with the decrease of temperature from 25°C to 10°C. At higher temperature >15°C, COD removal was above 94% while sewage treatment efficiency and relevant CH 4 production decreased below 15°C. The effluent COD at 10°C was 134mg/L at HRT of 16h. Moreover, low temperature can result in a higher membrane fouling rate due to the microbial self-protection behavior in coping with the temperature decrease by releasing soluble microbial products (SMP) and extracellular polymeric substances (EPS). The contribution of pore blocking to membrane fouling caused by protein from SMP and EPS increased from 17% to 45% and that of cake layer decreased from 81% to 53% at 25°C and 15°C respectively. The inhibition to hydrolysis and acidification process was responsible to the decrease of sewage treatment at lower temperature. Copyright © 2017 Elsevier Ltd. All rights reserved.

Functional response of a near-surface soil microbial community to a simulated underground CO2 storage leak.

Science.gov (United States)

Morales, Sergio E; Holben, William E

2013-01-01

Understanding the impacts of leaks from geologic carbon sequestration, also known as carbon capture and storage, is key to developing effective strategies for carbon dioxide (CO2) emissions management and mitigation of potential negative effects. Here, we provide the first report on the potential effects of leaks from carbon capture and storage sites on microbial functional groups in surface and near-surface soils. Using a simulated subsurface CO2 storage leak scenario, we demonstrate how CO2 flow upward through the soil column altered both the abundance (DNA) and activity (mRNA) of microbial functional groups mediating carbon and nitrogen transformations. These microbial responses were found to be seasonally dependent and correlated to shifts in atmospheric conditions. While both DNA and mRNA levels were affected by elevated CO2, they did not react equally, suggesting two separate mechanisms for soil microbial community response to high CO2 levels. The results did not always agree with previous studies on elevated atmospheric (rather than subsurface) CO2 using FACE (Free-Air CO2 Enrichment) systems, suggesting that microbial community response to CO2 seepage from the subsurface might differ from its response to atmospheric CO2 increases.

Aerobic carbon-cycle related microbial communities in boreal peatlands: responses to water-level drawdown

Energy Technology Data Exchange (ETDEWEB)

Peltoniemi, K

2010-07-01

Boreal peatlands represent a considerable portion of the global carbon (C) pool. Water-level drawdown (WLD) causes peatland drying and induces a vegetation change, which affects the decomposition of soil organic matter and the release of greenhouse gases (CO{sub 2} and CH{sub 4}). The objective of this thesis was to study the microbial communities related to the C cycle and their response to WLD in two boreal peatlands. Both sampling depth and site type had a strong impact on all microbial communities. In general, bacteria dominated the deeper layers of the nutrient-rich fen and the wettest surfaces of the nutrient-poor bog sites, whereas fungi seemed more abundant in the drier surfaces of the bog. WLD clearly affected the microbial communities but the effect was dependent on site type. The fungal and methane-oxidizing bacteria (MOB) community composition changed at all sites but the actinobacterial community response was apparent only in the fen after WLD. Microbial communities became more similar among sites after long-term WLD. Litter quality had a large impact on community composition, whereas the effects of site type and WLD were relatively minor. The decomposition rate of fresh organic matter was influenced slightly by actinobacteria, but not at all by fungi. Field respiration measurements in the northern fen indicated that WLD accelerates the decomposition of soil organic matter. In addition, a correlation between activity and certain fungal sequences indicated that community composition affects the decomposition of older organic matter in deeper peat layers. WLD had a negative impact on CH{sub 4} oxidation, especially in the oligotrophic fen. Fungal sequences were matched to taxa capable of utilizing a broad range of substrates. Most of the actinobacterial sequences could not be matched to characterized taxa in reference databases. This thesis represents the first investigation of microbial communities and their response to WLD among a variety of boreal

Effects of biochar and elevated soil temperature on soil microbial activity and abundance in an agricultural system

Science.gov (United States)

Bamminger, Chris; Poll, Christian; Marhan, Sven

2014-05-01

As a consequence of Global Warming, rising surface temperatures will likely cause increased soil temperatures. Soil warming has already been shown to, at least temporarily, increase microbial activity and, therefore, the emissions of greenhouse gases like CO2 and N2O. This underlines the need for methods to stabilize soil organic matter and to prevent further boost of the greenhouse gas effect. Plant-derived biochar as a soil amendment could be a valuable tool to capture CO2 from the atmosphere and sequestrate it in soil on the long-term. During the process of pyrolysis, plant biomass is heated in an oxygen-low atmosphere producing the highly stable solid matter biochar. Biochar is generally stable against microbial degradation due to its chemical structure and it, therefore, persists in soil for long periods. Previous experiments indicated that biochar improves or changes several physical or chemical soil traits such as water holding capacity, cation exchange capacity or soil structure, but also biotic properties like microbial activity/abundance, greenhouse gas emissions and plant growth. Changes in the soil microbial abundance and community composition alter their metabolism, but likely also affect plant productivity. The interaction of biochar addition and soil temperature increase on soil microbial properties and plant growth was yet not investigated on the field scale. To investigate whether warming could change biochar effects in soil, we conducted a field experiment attached to a soil warming experiment on an agricultural experimental site near the University of Hohenheim, already running since July 2008. The biochar field experiment was set up as two-factorial randomized block design (n=4) with the factors biochar amendment (0, 30 t ha-1) and soil temperature (ambient, elevated=ambient +2.5° C) starting from August 2013. Each plot has a dimension of 1x1m and is equipped with combined soil temperature and moisture sensors. Slow pyrolysis biochar from the C

Microbial habitat connectivity across spatial scales and hydrothermal temperature gradients at Guaymas Basin

Directory of Open Access Journals (Sweden)

Stefanie eMeyer

2013-07-01

Full Text Available The Guaymas Basin (Gulf of California hydrothermal vent area is known as a dynamic and hydrothermally vented sedimentary system, where the advection and production of a variety of different metabolic substrates support a high microbial diversity and activity in the seafloor. The main objective of our study was to explore the role of temperature and other environmental factors on community diversity, such as the presence of microbial mats and seafloor bathymetry within one hydrothermally vented field of 200 × 250 m dimension. In this field, temperature increased strongly with sediment depth reaching the known limit to life within a few decimeters. Potential sulfate reduction rate as a key community activity parameter was strongly affected by in situ temperature and sediment depth, declining from high rates of 1-5 μmol ml-1 d-1 at the surface to the detection limit below 5 cm sediment depth, despite the presence of sulfate and hydrocarbons. Automated Ribosomal Intergenic Spacer Analysis yielded a high-resolution fingerprint of the dominant members of the bacterial community. Our analyses showed strong temperature and sediment depth effects on bacterial cell abundance and Operational Taxonomic Units (OTUs number, both declining by more than one order of magnitude below the top 5 cm of the sediment surface. Another fraction of the variation in diversity and community structure was explained by differences in the local bathymetry and spatial position within the vent field. Nevertheless, more than 80% of all detected OTUs were shared among the different temperature realms and sediment depths, after being classified as cold (T<10°C, medium (10°C≤T<40°C or hot (T≥40°C temperature conditions, with significant OTU overlap with the richer surface communities. Overall, this indicates a high connectivity of benthic bacterial habitats in this dynamic and heterogeneous marine ecosystem influenced by strong hydrothermalism.

The Impact of Hydration and Temperature on Bacterial Diversity in Arid Soil Mesocosms

Directory of Open Access Journals (Sweden)

Adam Št'ovíček

2017-06-01

Full Text Available Hot desert ecosystems experience rare and unpredictable rainfall events that resuscitate the arid flora and fauna. However, the effect of this sudden abundance of water on soil microbial communities is still under debate. We modeled varying rainfall amounts and temperatures in desert soil mesocosms and monitored the microbial community response over a period of 21 days. We studied two different wetting events, simulating heavy (50 mm and light (10 mm rain, as well as three different temperature regimes: constant 25° or 36°C, or a temperature diurnal cycle alternating between 36 and 10 °C. Amplicon sequencing of the bacterial ribosomal RNA revealed that rain intensity affects the soil bacterial community, but the effects are mitigated by temperature. The combination of water-pulse intensity with lower temperature had the greatest effect on the bacterial community. These experiments demonstrated that the soil microbial response to rain events is dependent not only on the intensity of the water pulse but also on the ambient temperature, thus emphasizing the complexity of bacterial responses to highly unpredictable environments.

A sandwich-designed temperature-gradient incubator for studies of microbial temperature responses

DEFF Research Database (Denmark)

Elsgaard, Lars; Jørgensen, L.W.

2002-01-01

of 28-ml test tubes. An electric plate heats one end of the TGI end and the other end is cooled by thermoelectric Peltier elements in combination with a liquid cooling system. The TGI is equipped with 24 calibrated Pt-100 temperature sensors and insulated by polyurethane plates. A PC-operated SCADA...

CATALASE FROM A FUNGAL MICROBIAL PESTICIDE INDUCES A UNIQUE IGE RESPONSE.

Science.gov (United States)

BALB/c mice exposed by involuntary aspiration to Metarhizium anisopliae extract (MACA), a microbial pesticide, have shown responses characteristic of human allergic lung disease/asthma. IgE-binding proteins have been identified in MACA by Western blot analysis, 2-dimensio...

Taxonomic and Functional Responses of Soil Microbial Communities to Annual Removal of Aboveground Plant Biomass

Science.gov (United States)

Guo, Xue; Zhou, Xishu; Hale, Lauren; Yuan, Mengting; Feng, Jiajie; Ning, Daliang; Shi, Zhou; Qin, Yujia; Liu, Feifei; Wu, Liyou; He, Zhili; Van Nostrand, Joy D.; Liu, Xueduan; Luo, Yiqi; Tiedje, James M.; Zhou, Jizhong

2018-01-01

Clipping, removal of aboveground plant biomass, is an important issue in grassland ecology. However, few studies have focused on the effect of clipping on belowground microbial communities. Using integrated metagenomic technologies, we examined the taxonomic and functional responses of soil microbial communities to annual clipping (2010–2014) in a grassland ecosystem of the Great Plains of North America. Our results indicated that clipping significantly (P microbial respiration rates. Annual temporal variation within the microbial communities was much greater than the significant changes introduced by clipping, but cumulative effects of clipping were still observed in the long-term scale. The abundances of some bacterial and fungal lineages including Actinobacteria and Bacteroidetes were significantly (P microbial communities were significantly correlated with soil respiration and plant productivity. Intriguingly, clipping effects on microbial function may be highly regulated by precipitation at the interannual scale. Altogether, our results illustrated the potential of soil microbial communities for increased soil organic matter decomposition under clipping land-use practices. PMID:29904372

Is the mineralisation response to root exudation controlled by the microbial stoichiometric demand in subarctic soils?

Science.gov (United States)

Rousk, Johannes; Hicks, Lettice; Leizeaga, Ainara; Michelsen, Anders; Rousk, Kathrin

2017-04-01

Climate change will expose arctic and subarctic systems to warming and a shift towards plant communities with more rhizosphere labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1˚ C over ambient using open top chambers) and the addition of plant litter (90 g m-2 y-1) or organic nitrogen (N) (fungal fruit bodies; 90 g m-2 y-1) in the Subarctic influenced the susceptibility of SOM mineralisation to priming, and its microbial underpinnings. Root exudation were simulated with the addition of labile organic matter both in the form of only labile C (13C-glucose) or in the form of labile C and N (13C-alanine). We hypothesized that labile C would induce a higher mineralization of N than C sourced from SOM ("N mining"); a response unrelated to microbial growth responses. We also hypothesized that the N mining effect would be more pronounced in climate change simulation treatments of higher C/N (plant litter) than treatments with lower C/N (fungal fruitbodies and warming), with the control treatments intermediate. We also hypothesized that the addition of labile C and N would not result in selective N mining, but instead coupled responses of C and N mineralisation sourced from SOM; a response that would coincide with stimulated microbial growth responses. Labile C appeared to inhibit the mineralisation of C from SOM by up to 60% within hours. In contrast, the mineralisation of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile-C inhibited C mineralisation is compatible with previously reported findings termed 'preferential substrate utilisation' or 'negative apparent priming', while the stimulated N mineralisation responses echo recent reports of 'real priming' of SOM mineralisation. However, C and N mineralisation responses

Microbial Community Response to Simulated Petroleum Seepage in Caspian Sea Sediments

Directory of Open Access Journals (Sweden)

Katrin Knittel

2017-04-01

Full Text Available Anaerobic microbial hydrocarbon degradation is a major biogeochemical process at marine seeps. Here we studied the response of the microbial community to petroleum seepage simulated for 190 days in a sediment core from the Caspian Sea using a sediment-oil-flow-through (SOFT system. Untreated (without simulated petroleum seepage and SOFT sediment microbial communities shared 43% bacterial genus-level 16S rRNA-based operational taxonomic units (OTU0.945 but shared only 23% archaeal OTU0.945. The community differed significantly between sediment layers. The detection of fourfold higher deltaproteobacterial cell numbers in SOFT than in untreated sediment at depths characterized by highest sulfate reduction rates and strongest decrease of gaseous and mid-chain alkane concentrations indicated a specific response of hydrocarbon-degrading Deltaproteobacteria. Based on an increase in specific CARD-FISH cell numbers, we suggest the following groups of sulfate-reducing bacteria to be likely responsible for the observed decrease in aliphatic and aromatic hydrocarbon concentration in SOFT sediments: clade SCA1 for propane and butane degradation, clade LCA2 for mid- to long-chain alkane degradation, clade Cyhx for cycloalkanes, pentane and hexane degradation, and relatives of Desulfobacula for toluene degradation. Highest numbers of archaea of the genus Methanosarcina were found in the methanogenic zone of the SOFT core where we detected preferential degradation of long-chain hydrocarbons. Sequencing of masD, a marker gene for alkane degradation encoding (1-methylalkylsuccinate synthase, revealed a low diversity in SOFT sediment with two abundant species-level MasD OTU0.96.

Similar temperature dependencies of glycolytic enzymes: an evolutionary adaptation to temperature dynamics?

Directory of Open Access Journals (Sweden)

Cruz Luisa Ana B

2012-12-01

Full Text Available Abstract Background Temperature strongly affects microbial growth, and many microorganisms have to deal with temperature fluctuations in their natural environment. To understand regulation strategies that underlie microbial temperature responses and adaptation, we studied glycolytic pathway kinetics in Saccharomyces cerevisiae during temperature changes. Results Saccharomyces cerevisiae was grown under different temperature regimes and glucose availability conditions. These included glucose-excess batch cultures at different temperatures and glucose-limited chemostat cultures, subjected to fast linear temperature shifts and circadian sinoidal temperature cycles. An observed temperature-independent relation between intracellular levels of glycolytic metabolites and residual glucose concentration for all experimental conditions revealed that it is the substrate availability rather than temperature that determines intracellular metabolite profiles. This observation corresponded with predictions generated in silico with a kinetic model of yeast glycolysis, when the catalytic capacities of all glycolytic enzymes were set to share the same normalized temperature dependency. Conclusions From an evolutionary perspective, such similar temperature dependencies allow cells to adapt more rapidly to temperature changes, because they result in minimal perturbations of intracellular metabolite levels, thus circumventing the need for extensive modification of enzyme levels.

Lineage-specific responses of microbial communities to environmental change.

Science.gov (United States)

Youngblut, Nicholas D; Shade, Ashley; Read, Jordan S; McMahon, Katherine D; Whitaker, Rachel J

2013-01-01

A great challenge facing microbial ecology is how to define ecologically relevant taxonomic units. To address this challenge, we investigated how changing the definition of operational taxonomic units (OTUs) influences the perception of ecological patterns in microbial communities as they respond to a dramatic environmental change. We used pyrosequenced tags of the bacterial V2 16S rRNA region, as well as clone libraries constructed from the cytochrome oxidase C gene ccoN, to provide additional taxonomic resolution for the common freshwater genus Polynucleobacter. At the most highly resolved taxonomic scale, we show that distinct genotypes associated with the abundant Polynucleobacter lineages exhibit divergent spatial patterns and dramatic changes over time, while the also abundant Actinobacteria OTUs are highly coherent. This clearly demonstrates that different bacterial lineages demand different taxonomic definitions to capture ecological patterns. Based on the temporal distribution of highly resolved taxa in the hypolimnion, we demonstrate that change in the population structure of a single genotype can provide additional insight into the mechanisms of community-level responses. These results highlight the importance and feasibility of examining ecological change in microbial communities across taxonomic scales while also providing valuable insight into the ecological characteristics of ecologically coherent groups in this system.

Using community trait-distributions to assign microbial responses to pH changes and Cd in forest soils treated with wood ash

DEFF Research Database (Denmark)

Cruz Paredes, Carla; Wallander, Håkan; Kjøller, Rasmus

2017-01-01

is the current land-use. In forestry, wood ash has been proposed as a liming agent and a fertilizer, but has been questioned due to the risk associated with its Cd content. The aim of this study was to determine the effects of wood ash on the structure and function of decomposer microbial communities in forest......The identification of causal links between microbial community structure and ecosystem functions are required for a mechanistic understanding of ecosystem responses to environmental change. One of the most influential factors affecting plants and microbial communities in soil in managed ecosystems...... soils and to assign them to causal mechanisms. To do this, we assessed the responses to wood ash application of (i) the microbial community size and structure, (ii) microbial community trait-distributions, including bacterial pH relationships and Cd-tolerance, to assign the microbial responses to p...

Effect of temperature on microbial growth rate - thermodynamic analysis, the arrhenius and eyring-polanyi connection

Science.gov (United States)

The objective of this work is to develop a new thermodynamic mathematical model for evaluating the effect of temperature on the rate of microbial growth. The new mathematical model is derived by combining the Arrhenius equation and the Eyring-Polanyi transition theory. The new model, suitable for ...

Final technical report. Can microbial functional traits predict the response and resilience of decomposition to global change?

Energy Technology Data Exchange (ETDEWEB)

Allison, Steven D. [Univ. of California, Irvine, CA (United States)

2015-09-24

The role of specific micro-organisms in the carbon cycle, and their responses to environmental change, are unknown in most ecosystems. This knowledge gap limits scientists’ ability to predict how important ecosystem processes, like soil carbon storage and loss, will change with climate and other environmental factors. The investigators addressed this knowledge gap by transplanting microbial communities from different environments into new environments and measuring the response of community composition and carbon cycling over time. Using state-of-the-art sequencing techniques, computational tools, and nanotechnology, the investigators showed that microbial communities on decomposing plant material shift dramatically with natural and experimentally-imposed drought. Microbial communities also shifted in response to added nitrogen, but the effects were smaller. These changes had implications for carbon cycling, with lower rates of carbon loss under drought conditions, and changes in the efficiency of decomposition with nitrogen addition. Even when transplanted into the same conditions, microbial communities from different environments remained distinct in composition and functioning for up to one year. Changes in functioning were related to differences in enzyme gene content across different microbial groups. Computational approaches developed for this project allowed the conclusions to be tested more broadly in other ecosystems, and new computer models will facilitate the prediction of microbial traits and functioning across environments. The data and models resulting from this project benefit the public by improving the ability to predict how microbial communities and carbon cycling functions respond to climate change, nutrient enrichment, and other large-scale environmental changes.

Responses of redwood soil microbial community structure and N transformations to climate change

Science.gov (United States)

Damon C. Bradbury; Mary K. Firestone

2012-01-01

Soil microorganisms perform critical ecosystem functions, including decomposition, nitrogen (N) mineralization and nitrification. Soil temperature and water availability can be critical determinants of the rates of these processes as well as microbial community composition and structure. This research examined how changes in climate affect bacterial and fungal...

Cross-reactive microbial peptides can modulate HIV-specific CD8+ T cell responses.

Directory of Open Access Journals (Sweden)

Christopher W Pohlmeyer

Full Text Available Heterologous immunity is an important aspect of the adaptive immune response. We hypothesized that this process could modulate the HIV-1-specific CD8+ T cell response, which has been shown to play an important role in HIV-1 immunity and control. We found that stimulation of peripheral blood mononuclear cells (PBMCs from HIV-1-positive subjects with microbial peptides that were cross-reactive with immunodominant HIV-1 epitopes resulted in dramatic expansion of HIV-1-specific CD8+ T cells. Interestingly, the TCR repertoire of HIV-1-specific CD8+ T cells generated by ex vivo stimulation of PBMCs using HIV-1 peptide was different from that of cells stimulated with cross-reactive microbial peptides in some HIV-1-positive subjects. Despite these differences, CD8+ T cells stimulated with either HIV-1 or cross-reactive peptides effectively suppressed HIV-1 replication in autologous CD4+ T cells. These data suggest that exposure to cross-reactive microbial antigens can modulate HIV-1-specific immunity.

Microbial interactions with the cyanobacterium Microcystis aeruginosa and their dependence on temperature

DEFF Research Database (Denmark)

Dziallas, Claudia; Grossart, Hans-Peter

2012-01-01

and their associated community often masked this temperature effect. Both macro- and microenvironment of active cyanobacterial strains were characterized by high pH and oxygen values creating a unique habitat that potentially affects microbial diversity and function. For example, archaea including ‘anaerobic......Associated heterotrophic bacteria alter the microenvironment of cyanobacteria and potentially influence cyanobacterial development. Therefore, we studied interactions of the unicellular freshwater cyanobacterium Microcystis aeruginosa with heterotrophic bacteria. The associated bacterial community...... was greatly driven by temperature as seen by DNA Wngerprinting. However, the associated microbes also closely interacted with the cyanobacteria indicating changing ecological consequence of the associated bacterial community with temperature. Whereas concentration of dissolved organic carbon in cyanobacterial...

Effects of triclosan on host response and microbial biomarkers during experimental gingivitis.

Science.gov (United States)

Pancer, Brooke A; Kott, Diana; Sugai, James V; Panagakos, Fotinos S; Braun, Thomas M; Teles, Ricardo P; Giannobile, William V; Kinney, Janet S

2016-05-01

This exploratory randomized, controlled clinical trial sought to evaluate anti-inflammatory and -microbial effects of triclosan during experimental gingivitis as assessed by host response biomarkers and biofilm microbial pathogens. Thirty participants were randomized to triclosan or control dentifrice groups who ceased homecare for 21 days in an experimental gingivitis (EG) protocol. Plaque and gingival indices and saliva, plaque, and gingival crevicular fluid (GCF) were assessed/collected at days 0, 14, 21 and 35. Levels and proportions of 40 bacterial species from plaque samples were determined using checkerboard DNA-DNA hybridization. Ten biomarkers associated with inflammation, matrix degradation, and host protection were measured from GCF and saliva and analysed using a multiplex array. Participants were stratified as "high" or "low" responders based on gingival index and GCF biomarkers and bacterial biofilm were combined to generate receiver operating characteristic curves and predict gingivitis susceptibility. No differences in mean PI and GI values were observed between groups and non-significant trends of reduction of host response biomarkers with triclosan treatment. Triclosan significantly reduced levels of A. actinomycetemcomitans and P. gingivalis during induction of gingivitis. Triclosan reduced microbial levels during gingivitis development (ClinicalTrials.gov NCT01799226). © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Temperature modulates phototrophic periphyton response to chronic copper exposure

International Nuclear Information System (INIS)

Lambert, Anne Sophie; Dabrin, Aymeric; Morin, Soizic; Gahou, Josiane; Foulquier, Arnaud; Coquery, Marina; Pesce, Stéphane

2016-01-01

Streams located in vineyard areas are highly prone to metal pollution. In a context of global change, aquatic systems are generally subjected to multi-stress conditions due to multiple chemical and/or physical pressures. Among various environmental factors that modulate the ecological effects of toxicants, special attention should be paid to climate change, which is driving an increase in extreme climate events such as sharp temperature rises. In lotic ecosystems, periphyton ensures key ecological functions such as primary production and nutrient cycling. However, although the effects of metals on microbial communities are relatively well known, there is scant data on possible interactions between temperature increase and metal pollution. Here we led a study to evaluate the influence of temperature on the response of phototrophic periphyton to copper (Cu) exposure. Winter communities, collected in a 8 °C river water, were subjected for six weeks to four thermal conditions in microcosms in presence or not of Cu (nominal concentration of 15 μg L"−"1). At the initial river temperature (8 °C), our results confirmed the chronic impact of Cu on periphyton, both in terms of structure (biomass, distribution of algal groups, diatomic composition) and function (photosynthetic efficiency). At higher temperatures (13, 18 and 23 °C), Cu effects were modulated. Indeed, temperature increase reduced Cu effects on algal biomass, algal class proportions, diatom assemblage composition and photosynthetic efficiency. This reduction of Cu effects on periphyton may be related to lower bioaccumulation of Cu and/or to selection of more Cu-tolerant species at higher temperatures. - Highlights: • At in situ temperature, Cu impacted structure and activity of phototrophic biofilms. • Cu effects were reduced with increasing temperature (from +5 °C to +15 °C). • The decrease in Cu effects may be related to lower Cu bioaccumulation in biofilms. • Changes in diatom

Electricity generation of single-chamber microbial fuel cells at low temperatures

KAUST Repository

Cheng, Shaoan

2011-01-01

Practical applications of microbial fuel cells (MFCs) for wastewater treatment will require operation of these systems over a wide range of wastewater temperatures. MFCs at room or higher temperatures (20-35°C) are relatively well studied compared those at lower temperatures. MFC performance was examined here over a temperature range of 4-30°C in terms of startup time needed for reproducible power cycles, and performance. MFCs initially operated at 15°C or higher all attained a reproducible cycles of power generation, but the startup time to reach stable operation increased from 50h at 30°C to 210h at 15°C. At temperatures below 15°C, MFCs did not produce appreciable power even after one month of operation. If an MFC was first started up at temperature of 30°C, however, reproducible cycles of power generation could then be achieved at even the two lowest temperatures of 4°C and 10°C. Power production increased linearly with temperature at a rate of 33±4mW°C-1, from 425±2mWm-2 at 4°C to 1260±10mWm-2 at 30°C. Coulombic efficiency decreased by 45% over this same temperature range, or from CE=31% at 4°C to CE=17% at 30°C. These results demonstrate that MFCs can effectively be operated over a wide range of temperatures, but our findings have important implications for the startup of larger scale reactors where low wastewater temperatures could delay or prevent adequate startup of the system. © 2010 Elsevier B.V.

Atmospheric plasma processes for microbial inactivation: food applications and stress response in Listeria monocytogenes

OpenAIRE

Gozzi, Giorgia

2015-01-01

This PhD thesis is focused on cold atmospheric plasma treatments (GP) for microbial inactivation in food applications. In fact GP represents a promising emerging technology alternative to the traditional methods for the decontamination of foods. The objectives of this work were to evaluate: - the effects of GP treatments on microbial inactivation in model systems and in real foods; - the stress response in L. monocytogenes following exposure to different GP treatments. As far as t...

The transcriptional response of microbial communities in thawing Alaskan permafrost soils

Science.gov (United States)

Coolen, Marco J. L.; Orsi, William D.

2015-01-01

Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gasses, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after 11 days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM) was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw. PMID:25852660

The transcriptional response of microbial communities in thawing Alaskan permafrost soils

Directory of Open Access Journals (Sweden)

M J L Coolen

2015-03-01

Full Text Available Thawing of permafrost soils is expected to stimulate microbial decomposition and respiration of sequestered carbon. This could, in turn, increase atmospheric concentrations of greenhouse gases, such as carbon dioxide and methane, and create a positive feedback to climate warming. Recent metagenomic studies suggest that permafrost has a large metabolic potential for carbon processing, including pathways for fermentation and methanogenesis. Here, we performed a pilot study using ultrahigh throughput Illumina HiSeq sequencing of reverse transcribed messenger RNA to obtain a detailed overview of active metabolic pathways and responsible organisms in up to 70 cm deep permafrost soils at a moist acidic tundra location in Arctic Alaska. The transcriptional response of the permafrost microbial community was compared before and after eleven days of thaw. In general, the transcriptional profile under frozen conditions suggests a dominance of stress responses, survival strategies, and maintenance processes, whereas upon thaw a rapid enzymatic response to decomposing soil organic matter (SOM was observed. Bacteroidetes, Firmicutes, ascomycete fungi, and methanogens were responsible for largest transcriptional response upon thaw. Transcripts indicative of heterotrophic methanogenic pathways utilizing acetate, methanol, and methylamine were found predominantly in the permafrost table after thaw. Furthermore, transcripts involved in acetogenesis were expressed exclusively after thaw suggesting that acetogenic bacteria are a potential source of acetate for acetoclastic methanogenesis in freshly thawed permafrost. Metatranscriptomics is shown here to be a useful approach for inferring the activity of permafrost microbes that has potential to improve our understanding of permafrost SOM bioavailability and biogeochemical mechanisms contributing to greenhouse gas emissions as a result of permafrost thaw.

Microbial responses to carbon and nitrogen supplementation in an Antarctic dry valley soil

DEFF Research Database (Denmark)

Dennis, P. G.; Sparrow, A. D.; Gregorich, E. G.

2013-01-01

The soils of the McMurdo Dry Valleys are exposed to extremely dry and cold conditions. Nevertheless, they contain active biological communities that contribute to the biogeochemical processes. We have used ester-linked fatty acid (ELFA) analysis to investigate the effects of additions of carbon...... and nitrogen in glucose and ammonium chloride, respectively, on the soil microbial community in a field experiment lasting three years in the Garwood Valley. In the control treatment, the total ELFA concentration was small by comparison with temperate soils, but very large when expressed relative to the soil...... organic carbon concentration, indicating efficient conversion of soil organic carbon into microbial biomass and rapid turnover of soil organic carbon. The ELFA concentrations increased significantly in response to carbon additions, indicating that carbon supply was the main constraint to microbial...

Annual Removal of Aboveground Plant Biomass Alters Soil Microbial Responses to Warming

Directory of Open Access Journals (Sweden)

Kai Xue

2016-09-01

Full Text Available Clipping (i.e., harvesting aboveground plant biomass is common in agriculture and for bioenergy production. However, microbial responses to clipping in the context of climate warming are poorly understood. We investigated the interactive effects of grassland warming and clipping on soil properties and plant and microbial communities, in particular, on microbial functional genes. Clipping alone did not change the plant biomass production, but warming and clipping combined increased the C4 peak biomass by 47% and belowground net primary production by 110%. Clipping alone and in combination with warming decreased the soil carbon input from litter by 81% and 75%, respectively. With less carbon input, the abundances of genes involved in degrading relatively recalcitrant carbon increased by 38% to 137% in response to either clipping or the combined treatment, which could weaken long-term soil carbon stability and trigger positive feedback with respect to warming. Clipping alone also increased the abundance of genes for nitrogen fixation, mineralization, and denitrification by 32% to 39%. Such potentially stimulated nitrogen fixation could help compensate for the 20% decline in soil ammonium levels caused by clipping alone and could contribute to unchanged plant biomass levels. Moreover, clipping tended to interact antagonistically with warming, especially with respect to effects on nitrogen cycling genes, demonstrating that single-factor studies cannot predict multifactorial changes. These results revealed that clipping alone or in combination with warming altered soil and plant properties as well as the abundance and structure of soil microbial functional genes. Aboveground biomass removal for biofuel production needs to be reconsidered, as the long-term soil carbon stability may be weakened.

Responses of microbial biomass carbon and nitrogen to experimental warming: a meta-analysis

Science.gov (United States)

Xu, W.; Yuan, W.

2017-12-01

Soil microbes play important roles in regulating terrestrial carbon and nitrogen cycling and strongly influence feedbacks of ecosystem to global warming. However, the inconsistent responses of microbial biomass carbon (MBC) and nitrogen (MBN) to experimental warming have been observed, and the response on ratio between MBC and MBN (MBC:MBN) has not been identified. This meta-analysis synthesized the warming experiments at 58 sites globally to investigate the responses of MBC:MBN to climate warming. Our results showed that warming significantly increased MBC by 3.61 ± 0.80% and MBN by 5.85 ± 0.90% and thus decreased the MBC:MBN by 3.34 ± 0.66%. MBC showed positive responses to warming but MBN exhibited negative responses to warming at low warming magnitude (2°C) the results were inverted. The different effects of warming magnitude on microbial biomass resulted from the warming-induced decline in soil moisture and substrate supply. Moreover, MBC and MBN had strong positive responses to warming at the mid-term (3-4 years) or short-term (1-2 years) duration, but the responses tended to decrease at long-term (≥ 5 years) warming duration. This study fills the knowledge gap on the responses of MBC:MBN to warming and may benefit the development of coupled carbon and nitrogen models.

Soil microbial community responses to acid exposure and neutralization treatment.

Science.gov (United States)

Shin, Doyun; Lee, Yunho; Park, Jeonghyun; Moon, Hee Sun; Hyun, Sung Pil

2017-12-15

Changes in microbial community induced by acid shock were studied in the context of potential release of acids to the environment due to chemical accidents. The responses of microbial communities in three different soils to the exposure to sulfuric or hydrofluoric acid and to the subsequent neutralization treatment were investigated as functions of acid concentration and exposure time by using 16S-rRNA gene based pyrosequencing and DGGE (Denaturing Gradient Gel Electrophoresis). Measurements of soil pH and dissolved ion concentrations revealed that the added acids were neutralized to different degrees, depending on the mineral composition and soil texture. Hydrofluoric acid was more effectively neutralized by the soils, compared with sulfuric acid at the same normality. Gram-negative ß-Proteobacteria were shown to be the most acid-sensitive bacterial strains, while spore-forming Gram-positive Bacilli were the most acid-tolerant. The results of this study suggest that the Gram-positive to Gram-negative bacterial ratio may serve as an effective bio-indicator in assessing the impact of the acid shock on the microbial community. Neutralization treatments helped recover the ratio closer to their original values. The findings of this study show that microbial community changes as well as geochemical changes such as pH and dissolved ion concentrations need to be considered in estimating the impact of an acid spill, in selecting an optimal remediation strategy, and in deciding when to end remedial actions at the acid spill impacted site. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microbial Community Response to Terrestrially Derived Dissolved Organic Matter in the Coastal Arctic

Directory of Open Access Journals (Sweden)

Rachel E. Sipler

2017-06-01

Full Text Available Warming at nearly twice the global rate, higher than average air temperatures are the new ‘normal’ for Arctic ecosystems. This rise in temperature has triggered hydrological and geochemical changes that increasingly release carbon-rich water into the coastal ocean via increased riverine discharge, coastal erosion, and the thawing of the semi-permanent permafrost ubiquitous in the region. To determine the biogeochemical impacts of terrestrially derived dissolved organic matter (tDOM on marine ecosystems we compared the nutrient stocks and bacterial communities present under ice-covered and ice-free conditions, assessed the lability of Arctic tDOM to coastal microbial communities from the Chukchi Sea, and identified bacterial taxa that respond to rapid increases in tDOM. Once thought to be predominantly refractory, we found that ∼7% of dissolved organic carbon and ∼38% of dissolved organic nitrogen from tDOM was bioavailable to receiving marine microbial communities on short 4 – 6 day time scales. The addition of tDOM shifted bacterial community structure toward more copiotrophic taxa and away from more oligotrophic taxa. Although no single order was found to respond universally (positively or negatively to the tDOM addition, this study identified 20 indicator species as possible sentinels for increased tDOM. These data suggest the true ecological impact of tDOM will be widespread across many bacterial taxa and that shifts in coastal microbial community composition should be anticipated.

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.

Microbial transformations of C and N in a boreal forest floor as affected by temperature

NARCIS (Netherlands)

Verburg, P.S.J.; Dam, van D.; Hefting, M.M.; Tietema, A.

1999-01-01

The effects of temperature on N mineralization were studied in two organic surface horizons (LF and H) of soil from a boreal forest. The soil was incubated at 5 °C and 15 °C after adding 15 N and gross N fluxes were calculated using a numerical simulation model. The model was calibrated on microbial

Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments.

Science.gov (United States)

Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

2016-12-01

Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m -2  yr -1 ) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed 'preferential substrate utilization' or 'negative apparent priming', while the stimulated N mineralization responses echo recent reports of 'real priming' of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use. © 2016 John Wiley

Representing Microbial Dormancy in Soil Decomposition Models Improves Model Performance and Reveals Key Ecosystem Controls on Microbial Activity

Science.gov (United States)

He, Y.; Yang, J.; Zhuang, Q.; Wang, G.; Liu, Y.

2014-12-01

Climate feedbacks from soils can result from environmental change and subsequent responses of plant and microbial communities and nutrient cycling. Explicit consideration of microbial life history traits and strategy may be necessary to predict climate feedbacks due to microbial physiology and community changes and their associated effect on carbon cycling. In this study, we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of dormancy at six temperate forest sites with observed soil efflux ranged from 4 to 10 years across different forest types. We then extrapolated the model to all temperate forests in the Northern Hemisphere (25-50°N) to investigate spatial controls on microbial and soil C dynamics. Both models captured the observed soil heterotrophic respiration (RH), yet no-dormancy model consistently exhibited large seasonal amplitude and overestimation in microbial biomass. Spatially, the total RH from temperate forests based on dormancy model amounts to 6.88PgC/yr, and 7.99PgC/yr based on no-dormancy model. However, no-dormancy model notably overestimated the ratio of microbial biomass to SOC. Spatial correlation analysis revealed key controls of soil C:N ratio on the active proportion of microbial biomass, whereas local dormancy is primarily controlled by soil moisture and temperature, indicating scale-dependent environmental and biotic controls on microbial and SOC dynamics. These developments should provide essential support to modeling future soil carbon dynamics and enhance the avenue for collaboration between empirical soil experiment and modeling in the sense that more microbial physiological measurements are needed to better constrain and evaluate the models.

Importance of temperature and anodic medium composition on microbial fuel cell (MFC) performance

DEFF Research Database (Denmark)

Min, Booki; Romàn, Ó.B.; Angelidaki, Irini

2008-01-01

The performance of a microbial fuel cell (MFC) was investigated at different temperatures and anodic media. A lag phase of 30 h occurred at 30°C which was half that at room temperature (22°C). The maximum power density at 30°C was 70 mW/m2 and at 22°C was 43 mW/m2. At 15°C, no successful operation...... was observed even after several loadings for a long period of operation. Maximum power density of 320 mW/m2 was obtained with wastewater medium containing phosphate buffer (conductivity: 11.8 mS/cm), which was approx. 4 times higher than the value without phosphate additions (2.89 mS/cm)....

Non-microbial methane emissions from soils

Science.gov (United States)

Wang, Bin; Hou, Longyu; Liu, Wei; Wang, Zhiping

2013-12-01

Traditionally, methane (CH4) is anaerobically formed by methanogenic archaea. However, non-microbial CH4 can also be produced from geologic processes, biomass burning, animals, plants, and recently identified soils. Recognition of non-microbial CH4 emissions from soils remains inadequate. To better understand this phenomenon, a series of laboratory incubations were conducted to examine effects of temperature, water, and hydrogen peroxide (H2O2) on CH4 emissions under both aerobic and anaerobic conditions using autoclaved (30 min, 121 °C) soils and aggregates (>2000 μm, A1; 2000-250 μm, A2; 250-53 μm, M1; and A2 > A1 > M2 and C-based emission an order of M2 > M1 > A1 > A2, demonstrating that both organic carbon quantity and property are responsible for CH4 emissions from soils at the scale of aggregate. Whole soil-based order of A2 > A1 > M1 > M2 suggests that non-microbial CH4 release from forest soils is majorly contributed by macro-aggregates (i.e., >250 μm). The underlying mechanism is that organic matter through thermal treatment, photolysis, or reactions with free radicals produce CH4, which, in essence, is identical with mechanisms of other non-microbial sources, indicating that non-microbial CH4 production may be a widespread phenomenon in nature. This work further elucidates the importance of non-microbial CH4 formation which should be distinguished from the well-known microbial CH4 formation in order to define both roles in the atmospheric CH4 global budget.

Microbial Community Structure of a Leachfield Soil: Response to Intermittent Aeration and Tetracycline Addition

Directory of Open Access Journals (Sweden)

David A. Potts

2013-04-01

Full Text Available Soil-based wastewater treatment systems, or leachfields, rely on microbial processes for improving the quality of wastewater before it reaches the groundwater. These processes are affected by physicochemical system properties, such as O2 availability, and disturbances, such as the presence of antimicrobial compounds in wastewater. We examined the microbial community structure of leachfield mesocosms containing native soil and receiving domestic wastewater under intermittently-aerated (AIR and unaerated (LEACH conditions before and after dosing with tetracycline (TET. Community structure was assessed using phospholipid fatty acid analysis (PLFA, analysis of dominant phylotypes using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR–DGGE, and cloning and sequencing of 16S rRNA genes. Prior to dosing, the same PLFA biomarkers were found in soil from AIR and LEACH treatments, although AIR soil had a larger active microbial population and higher concentrations for nine of 32 PLFA markers found. AIR soil also had a larger number of dominant phylotypes, most of them unique to this treatment. Dosing of mesocosms with TET had a more marked effect on AIR than LEACH soil, reducing the size of the microbial population and the number and concentration of PLFA markers. Dominant phylotypes decreased by ~15% in response to TET in both treatments, although the AIR treatment retained a higher number of phylotypes than the LEACH treatment. Fewer than 10% of clones were common to both OPEN ACCESS Water 2013, 5 506 AIR and LEACH soil, and fewer than 25% of the clones from either treatment were homologous with isolates of known genus and species. These included human pathogens, as well as bacteria involved in biogeochemical transformations of C, N, S and metals, and biodegradation of various organic contaminants. Our results show that intermittent aeration has a marked effect on the size and structure of the microbial community that develops in

Performance and microbial community structure of a polar Arctic Circle aerobic granular sludge system operating at low temperature.

Science.gov (United States)

Gonzalez-Martinez, Alejandro; Muñoz-Palazon, Barbara; Maza-Márquez, Paula; Rodriguez-Sanchez, Alejandro; Gonzalez-Lopez, Jesus; Vahala, Riku

2018-05-01

The aim of this work was to study the performance and microbial community structure of a polar Arctic Circle aerobic granular sludge (AGS) system operating at low temperature. Thus, an AGS bioreactor was operated at 7, 5 and 3 °C of temperature using a cold-adapted sludge from Lapland. At 5 °C, it yielded acceptable conversion rates, in terms of nitrogen, phosphorous, and organic matter. However, under 3 °C a negligible nitrogen and phosphorous removal performance was observed. Below 5 °C, scanning electron microscopy studies showed a wispy, non-dense and irregular granular structure with a strong outgrowth of filamentous. Moreover, Illumina next-generation sequencing showed a heterogeneous microbial population where SM1K20 (Archaea), Trichosporon domesticum (Fungus), and Zooglea, Arcobacter and Acinetobacter (Bacteria) were the dominant phylotypes. Our study suggests that AGS technologies inoculated with North Pole sludge could be operated, in cold regions for a period longer than 3 months (winter season) under 5 °C of water temperature. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of changing temperature on anaerobic hydrogen production and microbial community composition in an open-mixed culture bioreactor

Energy Technology Data Exchange (ETDEWEB)

Karadag, Dogan; Puhakka, Jaakko A. [Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere (Finland)

2010-10-15

The temperature effect (37-65 C) on H{sub 2} production from glucose in an open-mixed culture bioreactor using an enrichment culture from a hot spring was studied. The dynamics of microbial communities was investigated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). At 45 and 60 C the H{sub 2} production was the highest i.e. 1.71 and 0.85 mol H{sub 2}/mol glucose, respectively. No H{sub 2} was produced at temperatures 50 and 55 C. At 37-45 C, H{sub 2} production was produced by butyrate type fermentation while fermentation mechanism changed to ethanol type at 60 C. Clostridium species were dominant at 37-45 C while at 50-55 C and 60 C the culture was dominated by Bacillus coagulans and Thermoanaerobacterium, respectively. In the presence of B. Coagulans the metabolism was directed to lactate production. The results show that the mixed culture had two optima for H{sub 2} production and that the microbial communities and metabolic patterns promptly changed according to changing temperatures. (author)

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

Science.gov (United States)

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

Temporal variability in Cu speciation, phytotoxicity, and soil microbial activity of Cu-polluted soils as affected by elevated temperature.

Science.gov (United States)

Fu, Qing-Long; Weng, Nanyan; Fujii, Manabu; Zhou, Dong-Mei

2018-03-01

Global warming has obtained increasing attentions due to its multiple impacts on agro-ecosystem. However, limited efforts had been devoted to reveal the temporal variability of metal speciation and phytotoxicity of heavy metal-polluted soils affected by elevated temperature under the global warming scenario. In this study, effects of elevated temperature (15 °C, 25 °C, and 35 °C) on the physicochemical properties, microbial metabolic activities, and phytotoxicity of three Cu-polluted soils were investigated by a laboratory incubation study. Soil physicochemical properties were observed to be significantly altered by elevated temperature with the degree of temperature effect varying in soil types and incubation time. The Biolog and enzymatic tests demonstrated that soil microbial activities were mainly controlled and decreased with increasing incubation temperature. Moreover, plant assays confirmed that the phytotoxicity and Cu uptake by wheat roots were highly dependent on soil types but less affected by incubation temperature. Overall, the findings in this study have highlighted the importance of soil types to better understand the temperature-dependent alternation of soil properties, Cu speciation and bioavailability, as well as phytotoxicity of Cu-polluted soils under global warming scenario. The present study also suggests the necessary of investigating effects of soil types on the transport and accumulation of toxic elements in soil-crop systems under global warming scenario. Copyright © 2017 Elsevier Ltd. All rights reserved.

Temperature response of soil respiration is dependent on concentration of readily decomposable C

Science.gov (United States)

Larionova, A. A.; Yevdokimov, I. V.; Bykhovets, S. S.

2007-12-01

Temperature acclimation of soil organic matter (SOM) decomposition is one of the major uncertainties in predicting soil CO2 efflux associated with the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006) based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax) and half-saturation constant (Ks) cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of data obtained in incubation experiments with forest and arable soils. Our data support the hypothesis and suggest that concentration of readily decomposable C substrate (as glucose equivalents) and temperature dependent substrate release are the important factors controlling temperature sensitivity of soil respiration. The highest temperature sensitivity of soil respiration was observed when substrate release was temperature dependent and C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant by glucose addition resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, attributing this phenomenon to changes in concentration of readily decomposable C substrate.

Taxonomic and functional diversity provides insight into microbial pathways and stress responses in the saline Qinghai Lake, China.

Directory of Open Access Journals (Sweden)

Qiuyuan Huang

Full Text Available Microbe-mediated biogeochemical cycles contribute to the global climate system and have sensitive responses and feedbacks to environmental stress caused by climate change. Yet, little is known about the effects of microbial biodiversity (i.e., taxonmic and functional diversity on biogeochemical cycles in ecosytems that are highly sensitive to climate change. One such sensitive ecosystem is Qinghai Lake, a high-elevation (3196 m saline (1.4% lake located on the Tibetan Plateau, China. This study provides baseline information on the microbial taxonomic and functional diversity as well as the associated stress response genes. Illumina metagenomic and metatranscriptomic datasets were generated from lake water samples collected at two sites (B and E. Autotrophic Cyanobacteria dominated the DNA samples, while heterotrophic Proteobacteria dominated the RNA samples at both sites. Photoheterotrophic Loktanella was also present at both sites. Photosystem II was the most active pathway at site B; while, oxidative phosphorylation was most active at site E. Organisms that expressed photosystem II or oxidative phosphorylation also expressed genes involved in photoprotection and oxidative stress, respectively. Assimilatory pathways associated with the nitrogen cycle were dominant at both sites. Results also indicate a positive relationship between functional diversity and the number of stress response genes. This study provides insight into the stress resilience of microbial metabolic pathways supported by greater taxonomic diversity, which may affect the microbial community response to climate change.

Response of core microbial consortia to hydrocarbon contaminations in coastal sediment habitats

Directory of Open Access Journals (Sweden)

Mathilde Jeanbille

2016-10-01

Full Text Available Traditionally, microbial surveys investigating the effect of chronic anthropogenic pressure such as polyaromatic hydrocarbons (PAHs contaminations consider just the alpha and beta diversity and ignore the interactions among the different taxa forming the microbial community. Here, we investigated the ecological relationships between the three domains of life (i.e. Bacteria, Archaea and Eukarya using 454 pyrosequencing data of the 16S rRNA and 18S rRNA genes from chronically impacted and pristine sediments, along the coasts of the Mediterranean Sea (Gulf of Lion, Vermillion coast, Corsica, Bizerte lagoon and Lebanon and the French Atlantic Ocean (Bay of Biscay and English Channel. Our approach provided a robust ecological framework for the partition of the taxa abundance distribution into 859 core OTUs and 6629 satellite OTUs. OTUs forming the core microbial community showed the highest sensitivity to changes in environmental and contaminant variations, with salinity, latitude, temperature, particle size distribution, total organic carbon (TOC and PAH concentrations as main drivers of community assembly. The core communities were dominated by Gammaproteobacteria and Deltaproteobacteria for Bacteria, by Thaumarchaeota, Bathyarchaeota and Thermoplasmata for Archaea and Metazoa and Dinoflagellata for Eukarya. In order to find associations among microorganisms, we generated a co-occurrence network in which PAHs were found to impact significantly the potential predator – prey relationship in one microbial consortium composed of ciliates and Actinobacteria. Comparison of network topological properties between contaminated and non-contaminated samples showed substantial differences in the structure of the network and indicated a higher vulnerability to environmental perturbations in the contaminated sediments.

The response of CD1d-restricted invariant NKT cells to microbial pathogens and their products

Directory of Open Access Journals (Sweden)

Luc eVan Kaer

2015-05-01

Full Text Available Invariant natural killer T (iNKT cells become activated during a wide variety of infections. This includes organisms lacking cognate CD1d-binding glycolipid antigens recognized by the semi-invariant T cell receptor of iNKT cells. Additional studies have shown that iNKT cells also become activated in vivo in response to microbial products such as bacterial lipopolysaccharide, a potent inducer of cytokine production in antigen-presenting cells (APCs. Other studies have shown that iNKT cells are highly responsive to stimulation by cytokines such as interleukin-12. These findings have led to the concept that microbial pathogens can activate iNKT cells either directly via glycolipids, or indirectly by inducing cytokine production in APCs. iNKT cells activated in this manner produce multiple cytokines that can influence the outcome of infection, usually in favor of the host, although potent iNKT cell activation may contribute to an uncontrolled cytokine storm and sepsis. One aspect of the response of iNKT cells to microbial pathogens is that it is short-lived and followed by an extended time period of unresponsiveness to reactivation. This refractory period may represent a means to avoid chronic activation and cytokine production by iNKT cells, thus protecting the host against some of the negative effects of iNKT cell activation, but potentially putting the host at risk for secondary infections. These effects of microbial pathogens and their products on iNKT cells are not only important for understanding the role of these cells in immune responses against infections but also for the development of iNKT cell-based therapies.

Community structure and function of high-temperature chlorophototrophic microbial mats inhabiting diverse geothermal environments

DEFF Research Database (Denmark)

Klatt, Christian G.; Inskeep, William P.; Herrgard, Markus

2013-01-01

Six phototrophic microbial mat communities from different geothermal springs (YNP) were studied using metagenome sequencing and geochemical analyses. The primary goals of this work were to determine differences in community composition of high-temperature phototrophic mats distributed across...... the Yellowstone geothermal ecosystem, and to identify metabolic attributes of predominant organisms present in these communities that may correlate with environmental attributes important in niche differentiation. Random shotgun metagenome sequences from six phototrophic communities (average 53Mbp/site) were...

Differential Gene Expression in Response to Salinity and Temperature in a Haloarcula Strain from Great Salt Lake, Utah

Directory of Open Access Journals (Sweden)

Swati Almeida-Dalmet

2018-01-01

Full Text Available Haloarchaea that inhabit Great Salt Lake (GSL, a thalassohaline terminal lake, must respond to the fluctuating climate conditions of the elevated desert of Utah. We investigated how shifting environmental factors, specifically salinity and temperature, affected gene expression in the GSL haloarchaea, NA6-27, which we isolated from the hypersaline north arm of the lake. Combined data from cultivation, microscopy, lipid analysis, antibiotic sensitivity, and 16S rRNA gene alignment, suggest that NA6-27 is a member of the Haloarcula genus. Our prior study demonstrated that archaea in the Haloarcula genus were stable in the GSL microbial community over seasons and years. In this study, RNA arbitrarily primed PCR (RAP-PCR was used to determine the transcriptional responses of NA6-27 grown under suboptimal salinity and temperature conditions. We observed alteration of the expression of genes related to general stress responses, such as transcription, translation, replication, signal transduction, and energy metabolism. Of the ten genes that were expressed differentially under stress, eight of these genes responded in both conditions, highlighting this general response. We also noted gene regulation specific to salinity and temperature conditions, such as osmoregulation and transport. Taken together, these data indicate that the GSL Haloarcula strain, NA6-27, demonstrates both general and specific responses to salinity and/or temperature stress, and suggest a mechanistic model for homeostasis that may explain the stable presence of this genus in the community as environmental conditions shift.

Microbial phylogeny determines transcriptional response of resistome to dynamic composting processes

OpenAIRE

Wang, Cheng; Dong, Da; Strong, P. J.; Zhu, Weijing; Ma, Zhuang; Qin, Yong; Wu, Weixiang

2017-01-01

Background Animal manure is a reservoir of antibiotic resistance genes (ARGs) that pose a potential health risk globally, especially for resistance to the antibiotics commonly used in livestock production (such as tetracycline, sulfonamide, and fluoroquinolone). Currently, the effects of biological treatment (composting) on the transcriptional response of manure ARGs and their microbial hosts are not well characterized. Composting is a dynamic process that consists of four distinct phases tha...

Response of microbial activities and diversity to PAHs contamination at coal tar contaminated land

Science.gov (United States)

Zhao, Xiaohui; Sun, Yujiao; Ding, Aizhong; Zhang, Dan; Zhang, Dayi

2015-04-01

Coal tar is one of the most hazardous and concerned organic pollutants and the main hazards are polycyclic aromatic hydrocarbons (PAHs). The indigenous microorganisms in soils are capable to degrade PAHs, with essential roles in biochemical process for PAHs natural attenuation. This study investigated 48 soil samples (from 8 depths of 6 boreholes) in Beijing coking and chemistry plant (China) and revealed the correlation between PAHs contamination, soil enzyme activities and microbial community structure, by 16S rRNA denaturing gradient gel electrophoresis (DGGE). At the site, the key contaminants were identified as naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene and anthracene, and the total PAHs concentration ranged from 0.1 to 923.9 mg/kg dry soil. The total PAHs contamination level was positively correlated (pcatalase activities (0.554-6.230 mL 0.02 M KMnO4/g•h) and dehydrogenase activities (1.9-30.4 TF μg/g•h soil), showing the significant response of microbial population and degrading functions to the organic contamination in soils. The PAHs contamination stimulated the PAHs degrading microbes and promoted their biochemical roles in situ. The positive relationship between bacteria count and dehydrogenase activities (p<0.05) suggested the dominancy of PAHs degrading bacteria in the microbial community. More interestingly, the microbial community deterioration was uncovered via the decline of microbial biodiversity (richness from 16S rRNA DGGE) against total PAHs concentration (p<0.05). Our research described the spatial profiles of PAHs contamination and soil microbial functions at the PAHs heavily contaminated sites, offering deeper understanding on the roles of indigenous microbial community in natural attenuation process.

Divergent taxonomic and functional responses of microbial communities to field simulation of aeolian soil erosion and deposition.

Science.gov (United States)

Ma, Xingyu; Zhao, Cancan; Gao, Ying; Liu, Bin; Wang, Tengxu; Yuan, Tong; Hale, Lauren; Nostrand, Joy D Van; Wan, Shiqiang; Zhou, Jizhong; Yang, Yunfeng

2017-08-01

Aeolian soil erosion and deposition have worldwide impacts on agriculture, air quality and public health. However, ecosystem responses to soil erosion and deposition remain largely unclear in regard to microorganisms, which are the crucial drivers of biogeochemical cycles. Using integrated metagenomics technologies, we analysed microbial communities subjected to simulated soil erosion and deposition in a semiarid grassland of Inner Mongolia, China. As expected, soil total organic carbon and plant coverage were decreased by soil erosion, and soil dissolved organic carbon (DOC) was increased by soil deposition, demonstrating that field simulation was reliable. Soil microbial communities were altered (p soil erosion and deposition, with dramatic increase in Cyanobacteria related to increased stability in soil aggregates. amyA genes encoding α-amylases were specifically increased (p = .01) by soil deposition and positively correlated (p = .02) to DOC, which likely explained changes in DOC. Surprisingly, most of microbial functional genes associated with carbon, nitrogen, phosphorus and potassium cycling were decreased or unaltered by both erosion and deposition, probably arising from acceleration of organic matter mineralization. These divergent responses support the necessity to include microbial components in evaluating ecological consequences. Furthermore, Mantel tests showed strong, significant correlations between soil nutrients and functional structure but not taxonomic structure, demonstrating close relevance of microbial function traits to nutrient cycling. © 2017 John Wiley & Sons Ltd.

Ecosystem and physiological scales of microbial responses to nutrients in a detritus-based stream: results of a 5-year continuous enrichment

Science.gov (United States)

Keller Suberkropp; Vladislav Gulis; Amy D. Rosemond; Jonathan Benstead

2010-01-01

Our study examined the response of leaf detritus–associated microorganisms (both bacteria and fungi) to a 5-yr continuous nutrient enrichment of a forested headwater stream. Leaf litter dominates detritus inputs to such streams and, on a system wide scale, serves as the key substrate for microbial colonization. We determined physiological responses as microbial biomass...

Temperature response of soil respiration is dependent on concentration of readily decomposable C

Directory of Open Access Journals (Sweden)

A. A. Larionova

2007-12-01

Full Text Available Temperature acclimation of soil organic matter (SOM decomposition is one of the major uncertainties in predicting soil CO₂ efflux associated with the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006 based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (V_max and half-saturation constant (K_s cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of data obtained in incubation experiments with forest and arable soils. Our data support the hypothesis and suggest that concentration of readily decomposable C substrate (as glucose equivalents and temperature dependent substrate release are the important factors controlling temperature sensitivity of soil respiration. The highest temperature sensitivity of soil respiration was observed when substrate release was temperature dependent and C substrate concentration was much lower than K_s. Increase of substrate content to the half-saturation constant by glucose addition resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate V_max leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, attributing this phenomenon to changes in concentration of readily decomposable C substrate.

Divergent Responses of Forest Soil Microbial Communities under Elevated CO2 in Different Depths of Upper Soil Layers.

Science.gov (United States)

Yu, Hao; He, Zhili; Wang, Aijie; Xie, Jianping; Wu, Liyou; Van Nostrand, Joy D; Jin, Decai; Shao, Zhimin; Schadt, Christopher W; Zhou, Jizhong; Deng, Ye

2018-01-01

Numerous studies have shown that the continuous increase of atmosphere CO 2 concentrations may have profound effects on the forest ecosystem and its functions. However, little is known about the response of belowground soil microbial communities under elevated atmospheric CO 2 (eCO 2 ) at different soil depth profiles in forest ecosystems. Here, we examined soil microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) after a 10-year eCO 2 exposure using a high-throughput functional gene microarray (GeoChip). The results showed that eCO 2 significantly shifted the compositions, including phylogenetic and functional gene structures, of soil microbial communities at both soil depths. Key functional genes, including those involved in carbon degradation and fixation, methane metabolism, denitrification, ammonification, and nitrogen fixation, were stimulated under eCO 2 at both soil depths, although the stimulation effect of eCO 2 on these functional markers was greater at the soil depth of 0 to 5 cm than of 5 to 15 cm. Moreover, a canonical correspondence analysis suggested that NO 3 -N, total nitrogen (TN), total carbon (TC), and leaf litter were significantly correlated with the composition of the whole microbial community. This study revealed a positive feedback of eCO 2 in forest soil microbial communities, which may provide new insight for a further understanding of forest ecosystem responses to global CO 2 increases. IMPORTANCE The concentration of atmospheric carbon dioxide (CO 2 ) has continuously been increasing since the industrial revolution. Understanding the response of soil microbial communities to elevated atmospheric CO 2 (eCO 2 ) is important for predicting the contribution of the forest ecosystem to global atmospheric change. This study analyzed the effect of eCO 2 on microbial communities at two soil depths (0 to 5 cm and 5 to 15 cm) in a forest ecosystem. Our findings suggest that the compositional and functional structures of microbial

Grassland to woodland transitions: Dynamic response of microbial community structure and carbon use patterns

Science.gov (United States)

Creamer, Courtney A.; Filley, Timothy R.; Boutton, Thomas W.; Rowe, Helen I.

2016-06-01

Woodland encroachment into grasslands is a globally pervasive phenomenon attributed to land use change, fire suppression, and climate change. This vegetation shift impacts ecosystem services such as ground water allocation, carbon (C) and nutrient status of soils, aboveground and belowground biodiversity, and soil structure. We hypothesized that woodland encroachment would alter microbial community structure and function and would be related to patterns in soil C accumulation. To address this hypothesis, we measured the composition and δ13C values of soil microbial phospholipids (PLFAs) along successional chronosequences from C4-dominated grasslands to C3-dominated woodlands (small discrete clusters and larger groves) spanning up to 134 years. Woodland development increased microbial biomass, soil C and nitrogen (N) concentrations, and altered microbial community composition. The relative abundance of gram-negative bacteria (cy19:0) increased linearly with stand age, consistent with decreases in soil pH and/or greater rhizosphere development and corresponding increases in C inputs. δ13C values of all PLFAs decreased with time following woody encroachment, indicating assimilation of woodland C sources. Among the microbial groups, fungi and actinobacteria in woodland soils selectively assimilated grassland C to a greater extent than its contribution to bulk soil. Between the two woodland types, microbes in the groves incorporated relatively more of the relict C4-C than those in the clusters, potentially due to differences in below ground plant C allocation and organo-mineral association. Changes in plant productivity and C accessibility (rather than C chemistry) dictated microbial C utilization in this system in response to shrub encroachment.

Resilience of Soil Microbial Communities to Metals and Additional Stressors: DNA-Based Approaches for Assessing “Stress-on-Stress” Responses

Directory of Open Access Journals (Sweden)

Hamed Azarbad

2016-06-01

Full Text Available Many microbial ecology studies have demonstrated profound changes in community composition caused by environmental pollution, as well as adaptation processes allowing survival of microbes in polluted ecosystems. Soil microbial communities in polluted areas with a long-term history of contamination have been shown to maintain their function by developing metal-tolerance mechanisms. In the present work, we review recent experiments, with specific emphasis on studies that have been conducted in polluted areas with a long-term history of contamination that also applied DNA-based approaches. We evaluate how the “costs” of adaptation to metals affect the responses of metal-tolerant communities to other stress factors (“stress-on-stress”. We discuss recent studies on the stability of microbial communities, in terms of resistance and resilience to additional stressors, focusing on metal pollution as the initial stress, and discuss possible factors influencing the functional and structural stability of microbial communities towards secondary stressors. There is increasing evidence that the history of environmental conditions and disturbance regimes play central roles in responses of microbial communities towards secondary stressors.

Soil Microbial Activity Responses to Fire in a Semi-arid Savannah Ecosystem Pre- and Post-Monsoon Season

Science.gov (United States)

Jimenez, J. R.; Raub, H. D.; Jong, E. L.; Muscarella, C. R.; Smith, W. K.; Gallery, R. E.

2017-12-01

Extracellular enzyme activities (EEA) of soil microorganisms can act as important proxies for nutrient limitation and turnover in soil and provide insight into the biochemical requirements of microbes in terrestrial ecosystems. In semi-arid ecosystems, microbial activity is influenced by topography, disturbances such as fire, and seasonality from monsoon rains. Previous studies from forest ecosystems show that microbial communities shift to similar compositions after severe fires despite different initial conditions. In semi-arid ecosystems with high spatial heterogeniety, we ask does fire lead to patch intensification or patch homogenization and how do monsoon rains influence the successional trajectories of microbial responses? We analyzed microbial activity and soil biogeochemistry throughout the monsoon season in paired burned and unburned sites in the Santa Rita Experimental Range, AZ. Surface soil (5cm) from bare-ground patches, bole, canopy drip line, and nearby grass patches for 5 mesquite trees per site allowed tests of spatiotemporal responses to fire and monsoon rain. Microbial activity was low during the pre-monsoon season and did not differ between the burned and unburned sites. We found greater activity near mesquite trees that reflects soil water and nutrient availability. Fire increased soil alkalinity, though soils near mesquite trees were less affected. Soil water content was significantly higher in the burned sites post-monsoon, potentially reflecting greater hydrophobicity of burned soils. Considering the effects of fire in these semi-arid ecosystems is especially important in the context of the projected changing climate regime in this region. Assessing microbial community recovery pre-, during, and post-monsoon is important for testing predictions about whether successional pathways post-fire lead to recovery or novel trajectories of communities and ecosystem function.

Effect of temperature on the anaerobic degradation of phenol and the microbial community

International Nuclear Information System (INIS)

Leven, L.; Schnurer, A.

2009-01-01

The residue produced during anaerobic digestion of organic waste is rich in nutrient and can be used as fertiliser However, one concern is the content of organic pollutants, as these may influence the soil fertility negatively and should therefore only occur at low levels. In this study, the effect of the process temperature on the anaerobic degradation of different phenolic compounds was investigated. Phenols have been shown to have a negative impact on soil microbial activity and can appear in anaerobic bioreactors both as components of the in-going substrate, and as intermediates during degradation of different complex aromatic compounds. (Author)

Mechanisms of microbial destabilization of soil C shifts over decades of warming

Science.gov (United States)

DeAngelis, K.; Pold, G.; Chowdhury, P. R.; Schnabel, J.; Grandy, S.; Melillo, J. M.

2017-12-01

Microbes are major actors in regulating the earth's biogeochemical cycles, with temperature-sensitive microbial tradeoffs improving ecosystem biogeochemical models. Meanwhile, the Earth's climate is changing, with decades of warming undercutting the ability of soil to store carbon. Our work explores trends of 26 years of experimental warming in temperate deciduous forest soils, which is associated with cycles of soil carbon degradation punctuated by periods of changes in soil microbial dynamics. Using a combination of biogeochemistry and molecular analytical methods, we explore the hypotheses that substrate availability, community structure, altered temperature sensitivity of microbial turnover-growth efficiency tradeoff, and microbial evolution are responsible for observations of accelerated degradation of soil carbon over time. Amplicon sequencing of microbial communities suggests a small role of changing microbial community composition over decades of warming, but a sustained suppression of fungal biomass is accompanied by increased biomass of Actinobacteria, Actinobacteria, Alphaproteobacteria, Verrucomicrobia and Planctomycetes. Substrate availability plays an important role in microbial dynamics, with depleted labile carbon in the first decade and depleted lignin in the second decade. Increased lignin-degrading enzyme activity supports the suggestion that lignin-like organic matter is an important substrate in chronically warmed soils. Metatranscriptomics data support the suggestion that increased turnover is associated with long-term warming, with metagenomic signals of increased carbohydrate-degrading enzymes in the organic horizon but decreased in the mineral soils. Finally, traits analysis of over 200 cultivated isolates of bacterial species from heated and control soils suggests an expanded ability for degradation of cellulose and hemicellulose but not chitin, supporting the hypothesis that long-term warming is exerting evolutionary pressure on microbial

Changes in coral-associated microbial communities during a bleaching event.

Science.gov (United States)

Bourne, David; Iida, Yuki; Uthicke, Sven; Smith-Keune, Carolyn

2008-04-01

Environmental stressors such as increased sea surface temperatures are well-known for contributing to coral bleaching; however, the effect of increased temperatures and subsequent bleaching on coral-associated microbial communities is poorly understood. Colonies of the hard coral Acropora millepora were tagged on a reef flat off Magnetic Island (Great Barrier Reef) and surveyed over 2.5 years, which included a severe bleaching event in January/February 2002. Daily average water temperatures exceeded the previous 10-year average by more than 1 degrees C for extended periods with field-based visual surveys recording all tagged colonies displaying signs of bleaching. During the bleaching period, direct counts of coral zooxanthellae densities decreased by approximately 64%, before recovery to pre-bleaching levels after the thermal stress event. A subset of three tagged coral colonies were sampled through the bleaching event and changes in the microbial community elucidated. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrated conserved bacterial banding profiles between the three coral colonies, confirming previous studies highlighting specific microbial associations. As coral colonies bleached, the microbial community shifted and redundancy analysis (RDA) of DGGE banding patterns revealed a correlation of increasing temperature with the appearance of Vibrio-affiliated sequences. Interestingly, this shift to a Vibrio-dominated community commenced prior to visual signs of bleaching. Clone libraries hybridized with Vibrio-specific oligonucleotide probes confirmed an increase in the fraction of Vibrio-affiliated clones during the bleaching period. Post bleaching, the coral microbial associations again shifted, returning to a profile similar to the fingerprints prior to bleaching. This provided further evidence for corals selecting and shaping their microbial partners. For non-bleached samples, a close association with Spongiobacter-related sequences were

VSS Degradation Kinetics in High Temperature Aerobic Digestion and Microbial Community Characteristics

Directory of Open Access Journals (Sweden)

Yunfen Shi

2018-01-01

Full Text Available Piggery wastewater is a kind of high concentration organic wastewater with high concentration of pollutants, large amount of emissions, and serious environmental pollution and is difficult to deal with. Piggery wastewater was treated with autothermal hyperthermia aerobic digestion process (ATAD and its biodegradation kinetics was studied. The ATAD system was automatically heated up and the reaction temperature rose from ambient temperature of 20°C to a maximum temperature of 64°C. Based on Arrhenius formula, the empirical model is obtained through dimensional analysis. The removal of volatile suspended solids (VSS was correlated with the initial VSS concentration, water inlet temperature, aeration rate, and agitation rate in the model. In the empirical model, the apparent activation energy was 2.827 kJ·mol−1. The exponentials for the initial VSS concentration, aeration rate, and stirring rate were 1.0587, −0.0976, and −0.1618, respectively. The correlation coefficient of the exponential factor was 0.9971. The VSS removal efficiency predicted by the model was validated with an actual test, showing a maximum relative deviation of 8.82%. Sludge systems show a lower diversity of microbial populations and Bacillus occupies a very important position in the reactor. The data obtained will be useful for optimizing piggery wastewater treatment process. The new model provided good theoretical guidance with good practicality.

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.

Comparison of the microbial communities of hot springs waters and the microbial biofilms in the acidic geothermal area of Copahue (Neuquén, Argentina).

Science.gov (United States)

Urbieta, María Sofía; González-Toril, Elena; Bazán, Ángeles Aguilera; Giaveno, María Alejandra; Donati, Edgardo

2015-03-01

Copahue is a natural geothermal field (Neuquén province, Argentina) dominated by the Copahue volcano. As a consequence of the sustained volcanic activity, Copahue presents many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. The occurrence of microbial biofilms was observed on the surrounding rocks and the borders of the ponds, where water movements and thermal activity are less intense. Microbial biofilms are particular ecological niches within geothermal environments; they present different geochemical conditions from that found in the water of the ponds and hot springs which is reflected in different microbial community structure. The aim of this study is to compare microbial community diversity in the water of ponds and hot springs and in microbial biofilms in the Copahue geothermal field, with particular emphasis on Cyanobacteria and other photosynthetic species that have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms.

Development of a high temperature microbial fermentation process for butanol

Energy Technology Data Exchange (ETDEWEB)

Jeor, Jeffery D. St. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Reed, David W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Daubaras, Dayna L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Vicki S. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-08-01

Transforming renewable biomass into cost-competitive high-performance biofuels and bioproducts is key to the U.S. future energy and chemical needs. Butanol production by microbial fermentation for chemical conversion to polyolefins, elastomers, drop-in jet or diesel fuel, and other chemicals is a promising solution. A high temperature fermentation process could decrease energy costs, capital cost, give higher butanol production, and allow for continuous fermentation. In this paper, we describe our approach to genetically transform Geobacillus caldoxylosiliticus, using a pUCG18 plasmid, for potential insertion of a butanol production pathway. Transformation methods tested were electroporation of electrocompetent cells, ternary conjugation with E. coli donor and helper strains, and protoplast fusion. These methods have not been successful using the current plasmid. Growth controls show cells survive the various methods tested, suggesting the possibility of transformation inhibition from a DNA restriction modification system in G. caldoxylosiliticus, as reported in the literature.

Temperature and relative humidity influence the microbial and physicochemical characteristics of Camembert-type cheese ripening.

Science.gov (United States)

Leclercq-Perlat, M-N; Sicard, M; Trelea, I C; Picque, D; Corrieu, G

2012-08-01

To evaluate the effects of temperature and relative humidity (RH) on microbial and biochemical ripening kinetics, Camembert-type cheeses were prepared from pasteurized milk seeded with Kluyveromyces marxianus, Geotrichum candidum, Penicillium camemberti, and Brevibacterium aurantiacum. Microorganism growth and biochemical changes were studied under different ripening temperatures (8, 12, and 16°C) and RH (88, 92, and 98%). The central point runs (12°C, 92% RH) were both reproducible and repeatable, and for each microbial and biochemical parameter, 2 kinetic descriptors were defined. Temperature had significant effects on the growth of both K. marxianus and G. candidum, whereas RH did not affect it. Regardless of the temperature, at 98% RH the specific growth rate of P. camemberti spores was significantly higher [between 2 (8°C) and 106 times (16°C) higher]. However, at 16°C, the appearance of the rind was no longer suitable because mycelia were damaged. Brevibacterium aurantiacum growth depended on both temperature and RH. At 8°C under 88% RH, its growth was restricted (1.3 × 10(7) cfu/g), whereas at 16°C and 98% RH, its growth was favored, reaching 7.9 × 10(9) cfu/g, but the rind had a dark brown color after d 20. Temperature had a significant effect on carbon substrate consumption rates in the core as well as in the rind. In the rind, when temperature was 16°C rather than 8°C, the lactate consumption rate was approximately 2.9 times higher under 88% RH. Whatever the RH, temperature significantly affected the increase in rind pH (from 4.6 to 7.7 ± 0.2). At 8°C, an increase in rind pH was observed between d 6 and 9, whereas at 16°C, it was between d 2 and 3. Temperature and RH affected the increasing rate of the underrind thickness: at 16°C, half of the cheese thickness appeared ripened on d 14 (wrapping day). However, at 98% RH, the underrind was runny. In conclusion, some descriptors, such as yeast growth and the pH in the rind, depended solely on

Soil mineral composition matters: response of microbial communities to phenanthrene and plant litter addition in long-term matured artificial soils.

Science.gov (United States)

Babin, Doreen; Vogel, Cordula; Zühlke, Sebastian; Schloter, Michael; Pronk, Geertje Johanna; Heister, Katja; Spiteller, Michael; Kögel-Knabner, Ingrid; Smalla, Kornelia

2014-01-01

The fate of polycyclic aromatic hydrocarbons (PAHs) in soil is determined by a suite of biotic and abiotic factors, and disentangling their role in the complex soil interaction network remains challenging. Here, we investigate the influence of soil composition on the microbial community structure and its response to the spiked model PAH compound phenanthrene and plant litter. We used long-term matured artificial soils differing in type of clay mineral (illite, montmorillonite) and presence of charcoal or ferrihydrite. The soils received an identical soil microbial fraction and were incubated for more than two years with two sterile manure additions. The matured artificial soils and a natural soil were subjected to the following spiking treatments: (I) phenanthrene, (II) litter, (III) litter + phenanthrene, (IV) unspiked control. Total community DNA was extracted from soil sampled on the day of spiking, 7, 21, and 63 days after spiking. Bacterial 16S rRNA gene and fungal internal transcribed spacer amplicons were quantified by qPCR and subjected to denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed that the bacterial community composition, which was strongly shaped by clay minerals after more than two years of incubation, changed in response to spiked phenanthrene and added litter. DGGE and qPCR showed that soil composition significantly influenced the microbial response to spiking. While fungal communities responded only in presence of litter to phenanthrene spiking, the response of the bacterial communities to phenanthrene was less pronounced when litter was present. Interestingly, microbial communities in all artificial soils were more strongly affected by spiking than in the natural soil, which might indicate the importance of higher microbial diversity to compensate perturbations. This study showed the influence of soil composition on the microbiota and their response to phenanthrene and litter, which may increase our understanding of

Microbial bebop: creating music from complex dynamics in microbial ecology.

Science.gov (United States)

Larsen, Peter; Gilbert, Jack

2013-01-01

In order for society to make effective policy decisions on complex and far-reaching subjects, such as appropriate responses to global climate change, scientists must effectively communicate complex results to the non-scientifically specialized public. However, there are few ways however to transform highly complicated scientific data into formats that are engaging to the general community. Taking inspiration from patterns observed in nature and from some of the principles of jazz bebop improvisation, we have generated Microbial Bebop, a method by which microbial environmental data are transformed into music. Microbial Bebop uses meter, pitch, duration, and harmony to highlight the relationships between multiple data types in complex biological datasets. We use a comprehensive microbial ecology, time course dataset collected at the L4 marine monitoring station in the Western English Channel as an example of microbial ecological data that can be transformed into music. Four compositions were generated (www.bio.anl.gov/MicrobialBebop.htm.) from L4 Station data using Microbial Bebop. Each composition, though deriving from the same dataset, is created to highlight different relationships between environmental conditions and microbial community structure. The approach presented here can be applied to a wide variety of complex biological datasets.

Differences in stability of seed-associated microbial assemblages in response to invasion by phytopathogenic microorganisms

Directory of Open Access Journals (Sweden)

Samir Rezki

2016-04-01

Full Text Available Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. However, little is known about the structure of seed-associated microbial assemblages and the regulators of assemblage structure. In this work, we have assessed the response of seed-associated microbial assemblages of Raphanus sativus to invading phytopathogenic agents, the bacterial strain Xanthomonas campestris pv. campestris (Xcc 8004 and the fungal strain Alternaria brassicicola Abra43. According to the indicators of bacterial (16S rRNA gene and gyrB sequences and fungal (ITS1 diversity employed in this study, seed transmission of the bacterial strain Xcc 8004 did not change the overall composition of resident microbial assemblages. In contrast seed transmission of Abra43 strongly modified the richness and structure of fungal assemblages without affecting bacterial assemblages. The sensitivity of seed-associated fungal assemblage to Abra43 is mostly related to changes in relative abundance of closely related fungal species that belong to the Alternaria genus. Variation in stability of the seed microbiota in response to Xcc and Abra43 invasions could be explained by differences in seed transmission pathways employed by these micro-organisms, which ultimately results in divergence in spatio-temporal colonization of the seed habitat.

Microbial inactivation of paprika by a high-temperature short-X time treatment. Influence on color properties.

Science.gov (United States)

Almela, Luis; Nieto-Sandoval, José M; Fernández López, José A

2002-03-13

High-temperature short-time (HTST) treatments have been used to destroy the bioburden of paprika. With this in mind, we have designed a device to treat samples of paprika with a gas whose temperature, pressure, and composition can be selected. Temperatures and treatment times ranged from 130 to 170 degrees C and 4 to 6 s, respectively. The survival of the most commonly found microorganisms in paprika and any alteration in extractable and superficial color were examined. Data showed that the optimum HTST conditions were 145 degrees C, 1.5 kg/cm2 of overpressure, 6 s operation time, and a thermal fluid of saturated steam. No microbial growth was detected during storage after thermal treatment. To minimize the color losses, treated (HTST) paprika samples should be kept under refrigeration.

Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

Science.gov (United States)

Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

2016-03-01

We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities.

Soil warming increases metabolic quotients of soil microorganisms without changes in temperature sensitivity of soil respiration

Science.gov (United States)

Marañón-Jiménez, Sara; Soong, Jenniffer L.; Leblans, Niki I. W.; Sigurdsson, Bjarni D.; Dauwe, Steven; Fransen, Erik; Janssens, Ivan A.

2017-04-01

Increasing temperatures can accelerate soil organic matter (SOM) decomposition and release large amounts of CO2 to the atmosphere, potentially inducing climate change feedbacks. Alterations to the temperature sensitivity and metabolic pathways of soil microorganisms in response to soil warming can play a key role in these soil carbon (C) losses. Here, we present results of an incubation experiment using soils from a geothermal gradient in Iceland that have been subjected to different intensities of soil warming (+0, +1, +3, +5, +10 and +20 °C above ambient) over seven years. We hypothesized that 7 years of soil warming would led to a depletion of labile organic substrates, with a subsequent decrease of the "apparent" temperature sensitivity of soil respiration. Associated to this C limitation and more sub-optimal conditions for microbial growth, we also hypothesized increased microbial metabolic quotients (soil respiration per unit of microbial biomass), which is associated with increases in the relative amount of C invested into catabolic pathways along the warming gradient. Soil respiration and basal respiration rates decreased with soil warming intensity, in parallel with a decline in soil C availability. Contrasting to our first hypothesis, we did not detect changes in the temperature sensitivity of soil respiration with soil warming or on the availability of nutrients and of labile C substrates at the time of incubation. However, in agreement to our second hypothesis, microbial metabolic quotients (soil respiration per unit of microbial biomass) increased at warmer temperatures, while the C retained in biomass decreased as substrate became limiting. Long-term (7 years) temperature increases thus triggered a change in the metabolic functioning of the soil microbial communities towards increasing energy costs for maintenance or resource acquisition, thereby lowering the capacity of C retention and stabilization of warmed soils. These results highlight the need

Temperature influence on chemical toxicity to aquatic organisms

International Nuclear Information System (INIS)

Cairns, J. Jr.; Heath, A.G.; Parker, B.C.

1975-01-01

The literature on the effects of temperature on chemical toxicity to aquatic animals and microorganisms is reviewed. Microbial photosynthesis and respiration is briefly discussed. It is concluded that there is a paucity of information on the inter-relations of temperature and toxicants to algae, bacteria, and protozoa and that standards based on the in situ response of indigenous organisms to specific discharge areas should be developed

Environmental proteomics reveals early microbial community responses to biostimulation at a uranium- and nitrate-contaminated site

Energy Technology Data Exchange (ETDEWEB)

Chourey, Karuna [ORNL; Nissen, Silke [ORNL; Vishnivetskaya, T. [University of Tennessee, Knoxville (UTK); Shah, Manesh B [ORNL; Pffifner, Susan [University of Tennessee, Knoxville (UTK); Hettich, Robert {Bob} L [ORNL; Loeffler, Frank E [ORNL

2013-01-01

High performance mass spectrometry instrumentation coupled with improved protein extraction techniques enable metaproteomics to identify active members of soil and groundwater microbial communities. Metaproteomics workflows were applied to study the initial responses (i.e., 4 days post treatment) of the indigenous aquifer microbiota to biostimulation with emulsified vegetable oil (EVO) at a uranium-contaminated site. Members of the Betaproteobacteria (i.e., Dechloromonas, Ralstonia, Rhodoferax, Polaromonas, Delftia, Chromobacterium) and Firmicutes dominated the biostimulated aquifer community. Proteome characterization revealed distinct differences in protein expression between the microbial biomass collected from groundwater influenced by biostimulation and groundwater collected up-gradient of the EVO injection points. In particular, proteins involved in ammonium assimilation, EVO degradation, and polyhydroxybutyrate (PHB) granule formation were prominent following biostimulation. Interestingly, the atypical NosZ of a Dechloromonas sp. was highly expressed suggesting active nitrous oxide (N2O) respiration. c-type cytochromes were barely detected, as was citrate synthase, a biomarker for hexavalent uranium reduction activity, suggesting that metal reduction has not commenced 4 days post EVO delivery. Environmental metaproteomics identified microbial community responses to biostimulation and elucidated active pathways demonstrating the value of this technique for complementing nucleic acid-based approaches.

RESPONSE OF SOIL MICROBIAL BIOMASS AND COMMUNITY COMPOSITION TO CHRONIC NITROGEN ADDITIONS AT HARVARD FOREST

Science.gov (United States)

Soil microbial communities may respond to anthropogenic increases in ecosystem nitrogen (N) availability, and their response may ultimately feedback on ecosystem carbon and N dynamics. We examined the long-term effects of chronic N additions on soil microbes by measuring soil mi...

Microbial biosensors for environmental monitoring

Directory of Open Access Journals (Sweden)

David VOGRINC

2015-12-01

Full Text Available Microbial biosensors are analytical devices capable of sensing substances in the environment due to the specific biological reaction of the microorganism or its parts. Construction of a microbial biosensor requires knowledge of microbial response to the specific analyte. Linking this response with the quantitative data, using a transducer, is the crucial step in the construction of a biosensor. Regarding the transducer type, biosensors are divided into electrochemical, optical biosensors and microbial fuel cells. The use of the proper configuration depends on the selection of the biosensing element. With the use of transgenic E. coli strains, bioluminescence or fluorescence based biosensors were developed. Microbial fuel cells enable the use of the heterogeneous microbial populations, isolated from wastewater. Different microorganisms are used for different pollutants – pesticides, heavy metals, phenolic compounds, organic waste, etc. Biosensing enables measurement of their concentration and their toxic or genotoxic effects on the microbes. Increasing environmental awareness has contributed to the increase of interest for biomonitoring. Although technologies, such as bioinformatics and genetic engineering, allow us to design complex and efficient microbial biosensors for environmental pollutants, the transfer of the laboratory work to the field still remains a problem to solve.

The YNP Metagenome Project: Environmental Parameters Responsible for Microbial Distribution in the Yellowstone Geothermal Ecosystem

Directory of Open Access Journals (Sweden)

William P. Inskeep

2013-05-01

Full Text Available The Yellowstone geothermal complex contains over 10,000 diverse geothermal features that host numerous phylogenetically deeply-rooted and poorly understood archaea, bacteria and viruses. Microbial communities in high-temperature environments are generally less diverse than soil, marine, sediment or lake habitats and therefore offer a tremendous opportunity for studying the structure and function of different model microbial communities using environmental metagenomics. One of the broader goals of this study was to establish linkages among microbial distribution, metabolic potential and environmental variables. Twenty geochemically distinct geothermal ecosystems representing a broad spectrum of Yellowstone hot-spring environments were used for metagenomic and geochemical analysis and included approximately equal numbers of: (1 phototrophic mats, (2 ‘filamentous streamer’ communities, and (3 archaeal-dominated sediments. The metagenomes were analyzed using a suite of complementary and integrative bioinformatic tools, including phylogenetic and functional analysis of both individual sequence reads and assemblies of predominant phylotypes. This volume identifies major environmental determinants of a large number of thermophilic microbial lineages, many of which have not been fully described in the literature nor previously cultivated to enable functional and genomic analyses. Moreover, protein family abundance comparisons and in-depth analyses of specific genes and metabolic pathways relevant to these hot-spring environments reveal hallmark signatures of metabolic capabilities that parallel the distribution of phylotypes across specific types of geochemical environments.

Changes in the microbial community structure of bacteria, archaea and fungi in response to elevated CO(2) and warming in an Australian native grassland soil.

Science.gov (United States)

Hayden, Helen L; Mele, Pauline M; Bougoure, Damian S; Allan, Claire Y; Norng, Sorn; Piceno, Yvette M; Brodie, Eoin L; Desantis, Todd Z; Andersen, Gary L; Williams, Amity L; Hovenden, Mark J

2012-12-01

The microbial community structure of bacteria, archaea and fungi is described in an Australian native grassland soil after more than 5 years exposure to different atmospheric CO2 concentrations ([CO2]) (ambient, +550 ppm) and temperatures (ambient, + 2°C) under different plant functional types (C3 and C4 grasses) and at two soil depths (0-5 cm and 5-10 cm). Archaeal community diversity was influenced by elevated [CO2], while under warming archaeal 16S rRNA gene copy numbers increased for C4 plant Themeda triandra and decreased for the C3 plant community (P fungi in soil responded differently to elevated [CO2], warming and their interaction. Taxa identified as significantly climate-responsive could show differing trends in the direction of response ('+' or '-') under elevated CO2 or warming, which could then not be used to predict their interactive effects supporting the need to investigate interactive effects for climate change. The approach of focusing on specific taxonomic groups provides greater potential for understanding complex microbial community changes in ecosystems under climate change. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Temporal dynamics of hot desert microbial communities reveal structural and functional responses to water input.

Science.gov (United States)

Armstrong, Alacia; Valverde, Angel; Ramond, Jean-Baptiste; Makhalanyane, Thulani P; Jansson, Janet K; Hopkins, David W; Aspray, Thomas J; Seely, Mary; Trindade, Marla I; Cowan, Don A

2016-09-29

The temporal dynamics of desert soil microbial communities are poorly understood. Given the implications for ecosystem functioning under a global change scenario, a better understanding of desert microbial community stability is crucial. Here, we sampled soils in the central Namib Desert on sixteen different occasions over a one-year period. Using Illumina-based amplicon sequencing of the 16S rRNA gene, we found that α-diversity (richness) was more variable at a given sampling date (spatial variability) than over the course of one year (temporal variability). Community composition remained essentially unchanged across the first 10 months, indicating that spatial sampling might be more important than temporal sampling when assessing β-diversity patterns in desert soils. However, a major shift in microbial community composition was found following a single precipitation event. This shift in composition was associated with a rapid increase in CO 2 respiration and productivity, supporting the view that desert soil microbial communities respond rapidly to re-wetting and that this response may be the result of both taxon-specific selection and changes in the availability or accessibility of organic substrates. Recovery to quasi pre-disturbance community composition was achieved within one month after rainfall.

Temporal dynamics of hot desert microbial communities reveal structural and functional responses to water input

Energy Technology Data Exchange (ETDEWEB)

Armstrong, Alacia; Valverde, Angel; Ramond, Jean-Baptiste; Makhalanyane, Thulani P.; Jansson, Janet K.; Hopkins, David W.; Aspray, Thomas J.; Seely, Mary; Trindade, Marla I.; Cowan, Don A.

2016-09-29

The temporal dynamics of desert soil microbial communities are poorly understood. Given the implications for ecosystem functioning under a global change scenario, a better understanding of desert microbial community stability is crucial. Here, we sampled soils in the central Namib Desert on sixteen different occasions over a one-year period. Using Illumina-based amplicon sequencing of the 16S rRNA gene, we found that α-diversity (richness) was more variable at a given sampling date (spatial variability) than over the course of one year (temporal variability). Community composition remained essentially unchanged across the first 10 months, indicating that spatial sampling might be more important than temporal sampling when assessing β-diversity patterns in desert soils. However, a major shift in microbial community composition was found following a single precipitation event. This shift in composition was associated with a rapid increase in CO2 respiration and productivity, supporting the view that desert soil microbial communities respond rapidly to re-wetting and that this response may be the result of both taxon-specific selection and changes in the availability or accessibility of organic substrates. Recovery to quasi pre-disturbance community composition was achieved within one month after rainfall.

Response of soil microbial communities to roxarsone pollution along a concentration gradient.

Science.gov (United States)

Liu, Yaci; Zhang, Zhaoji; Li, Yasong; Wen, Yi; Fei, Yuhong

2017-07-29

The extensive use of roxarsone (3-nitro-4-hydroxyphenylarsonic acid) as a feed additive in the broiler poultry industry can lead to environmental arsenic contamination. This study was conducted to reveal the response of soil microbial communities to roxarsone pollution along a concentration gradient. To explore the degradation process and degradation kinetics of roxarsone concentration gradients in soil, the concentration shift of roxarsone at initial concentrations of 0, 50, 100, and 200 mg/kg, as well as that of the arsenic derivatives, was detected. The soil microbial community composition and structure accompanying roxarsone degradation were investigated by high-throughput sequencing. The results showed that roxarsone degradation was inhibited by a biological inhibitor, confirming that soil microbes were absolutely essential to its degradation. Moreover, soil microbes had considerable potential to degrade roxarsone, as a high initial concentration of roxarsone resulted in a substantially increased degradation rate. The concentrations of the degradation products HAPA (3-amino-4-hydroxyphenylarsonic acid), AS(III), and AS(V) in soils were significantly positively correlated. The soil microbial community composition and structure changed significantly across the roxarsone contamination gradient, and the addition of roxarsone decreased the microbial diversity. Some bacteria tended to be inhibited by roxarsone, while Bacillus, Paenibacillus, Arthrobacter, Lysobacter, and Alkaliphilus played important roles in roxarsone degradation. Moreover, HAPA, AS(III), and AS(V) were significantly positively correlated with Symbiobacterium, which dominated soils containing roxarsone, and their abundance increased with increasing initial roxarsone concentration. Accordingly, Symbiobacterium could serve as indicator of arsenic derivatives released by roxarsone as well as the initial roxarsone concentration. This is the first investigation of microbes closely related to roxarsone

Seasonal Variations of Indoor Microbial Exposures and Their Relation to Temperature, Relative Humidity, and Air Exchange Rate

DEFF Research Database (Denmark)

Frankel, Mika; Bekö, Gabriel; Timm, Michael

2012-01-01

with temperature, relative humidity, and air exchange rates in Danish homes. Airborne inhalable dust was sampled in five Danish homes throughout the four seasons of 1 year (indoors, n = 127; outdoors, n = 37). Measurements included culturable fungi and bacteria, endotoxin, N-acetyl-beta-d-glucosaminidase, total...... inflammatory potential, particles (0.75 to 15 μm), temperature, relative humidity, and air exchange rates. Significant seasonal variation was found for all indoor microbial exposures, excluding endotoxin. Indoor fungi peaked in summer (median, 235 CFU/m3) and were lowest in winter (median, 26 CFU/m3). Indoor...... of inhalable dust and number of particles. Temperature and air exchange rates were positively associated with fungi and N-acetyl-beta-d-glucosaminidase and negatively with bacteria and the total inflammatory potential. Although temperature, relative humidity, and air exchange rates were significantly...

Syntrophic interactions drive the hydrogen production from glucose at low temperature in microbial electrolysis cells

KAUST Repository

Lu, Lu

2012-11-01

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 in single-chamber MECs at a yield of about 6mol H2mol-1 glucose, and at rates of 0.25±0.03-0.37±0.04m3 H2m-3d-1. Pyrosequencing of 16S rRNA gene and electrochemical analyses showed that syntrophic interactions combining glucose fermentation with the oxidization of fermentation products by exoelectrogens was the predominant pathway for current production at a low temperature other than direct glucose oxidization by exoelectrogens. Another syntrophic interaction, methanogenesis and homoacetogenesis, which have been found in 25°C reactors, were not detected in MECs at 4°C. These results demonstrate the feasibility of H2 production from abundant biomass of carbohydrates at low temperature in MECs. © 2012 Elsevier Ltd.

Microbial bebop: creating music from complex dynamics in microbial ecology.

Directory of Open Access Journals (Sweden)

Peter Larsen

Full Text Available In order for society to make effective policy decisions on complex and far-reaching subjects, such as appropriate responses to global climate change, scientists must effectively communicate complex results to the non-scientifically specialized public. However, there are few ways however to transform highly complicated scientific data into formats that are engaging to the general community. Taking inspiration from patterns observed in nature and from some of the principles of jazz bebop improvisation, we have generated Microbial Bebop, a method by which microbial environmental data are transformed into music. Microbial Bebop uses meter, pitch, duration, and harmony to highlight the relationships between multiple data types in complex biological datasets. We use a comprehensive microbial ecology, time course dataset collected at the L4 marine monitoring station in the Western English Channel as an example of microbial ecological data that can be transformed into music. Four compositions were generated (www.bio.anl.gov/MicrobialBebop.htm. from L4 Station data using Microbial Bebop. Each composition, though deriving from the same dataset, is created to highlight different relationships between environmental conditions and microbial community structure. The approach presented here can be applied to a wide variety of complex biological datasets.

Microbial Sulfate Reduction in Deep-Sea Sediments at the Guaymas Basin - Hydrothermal Vent Area - Influence of Temperature and Substrates

DEFF Research Database (Denmark)

ELSGAARD, L.; ISAKSEN, MF; JØRGENSEN, BB

1994-01-01

Microbial sulfate reduction was studied by a S-35 tracer technique in sediments from the hydrothermal vent site in Guaymas Basin, Gulf of California, Mexico. In situ temperatures ranged from 2.7-degrees-C in the overlying seawater to > 120-degrees-C at 30 cm depth in the hydrothermal sediment...

Multitaxon activity profiling reveals differential microbial response to reduced seawater pH and oil pollution.

Science.gov (United States)

Coelho, Francisco J R C; Cleary, Daniel F R; Costa, Rodrigo; Ferreira, Marina; Polónia, Ana R M; Silva, Artur M S; Simões, Mário M Q; Oliveira, Vanessa; Gomes, Newton C M

2016-09-01

There is growing concern that predicted changes to global ocean chemistry will interact with anthropogenic pollution to significantly alter marine microbial composition and function. However, knowledge of the compounding effects of climate change stressors and anthropogenic pollution is limited. Here, we used 16S and 18S rRNA (cDNA)-based activity profiling to investigate the differential responses of selected microbial taxa to ocean acidification and oil hydrocarbon contamination under controlled laboratory conditions. Our results revealed that a lower relative abundance of sulphate-reducing bacteria (Desulfosarcina/Desulfococcus clade) due to an adverse effect of seawater acidification and oil hydrocarbon contamination (reduced pH-oil treatment) may be coupled to changes in sediment archaeal communities. In particular, we observed a pronounced compositional shift and marked reduction in the prevalence of otherwise abundant operational taxonomic units (OTUs) belonging to the archaeal Marine Benthic Group B and Marine Hydrothermal Vent Group (MHVG) in the reduced pH-oil treatment. Conversely, the abundance of several putative hydrocarbonoclastic fungal OTUs was higher in the reduced pH-oil treatment. Sediment hydrocarbon profiling, furthermore, revealed higher concentrations of several alkanes in the reduced pH-oil treatment, corroborating the functional implications of the structural changes to microbial community composition. Collectively, our results advance the understanding of the response of a complex microbial community to the interaction between reduced pH and anthropogenic pollution. In future acidified marine environments, oil hydrocarbon contamination may alter the typical mixotrophic and k-/r-strategist composition of surface sediment microbiomes towards a more heterotrophic state with lower doubling rates, thereby impairing the ability of the ecosystem to recover from acute oil contamination events. © 2016 John Wiley & Sons Ltd.

Microbial Shifts in the Intestinal Microbiota of Salmonella Infected Chickens in Response to Enrofloxacin.

Science.gov (United States)

Li, Jun; Hao, Haihong; Cheng, Guyue; Liu, Chunbei; Ahmed, Saeed; Shabbir, Muhammad A B; Hussain, Hafiz I; Dai, Menghong; Yuan, Zonghui

2017-01-01

Fluoroquinolones (FQs) are important antibiotics used for treatment of Salmonella infection in poultry in many countries. However, oral administration of fluoroquinolones may affect the composition and abundance of a number of bacterial taxa in the chicken intestine. Using 16S rRNA gene sequencing, the microbial shifts in the gut of Salmonella infected chickens in response to enrofloxacin treatments at different dosages (0, 0.1, 4, and 100 mg/kg b.w.) were quantitatively evaluated. The results showed that the shedding levels of Salmonella were significantly reduced in the high dosage group as demonstrated by both the culturing method and 16S rRNA sequencing method. The average values of diversity indices were higher in the control group than in the three medicated groups. Non-metric multidimensional scaling (NMDS) analysis results showed that the microbial community of high dosage group was clearly separated from the other three groups. In total, 25 genera were significantly enriched (including 6 abundant genera: Lactococcus , Bacillus , Burkholderia , Pseudomonas , Rhizobium , and Acinetobacter ) and 23 genera were significantly reduced in the medicated groups than in the control group for the treatment period, but these bacterial taxa recovered to normal levels after therapy withdrawal. Additionally, 5 genera were significantly reduced in both treatment and withdrawal periods (e.g., Blautia and Anaerotruncus ) and 23 genera (e.g., Enterobacter and Clostridium ) were significantly decreased only in the withdrawal period, indicating that these genera might be the potential targets for the fluoroquinolones antimicrobial effects. Specially, Enterococcus was significantly reduced under high dosage of enrofloxacin treatment, while significantly enriched in the withdrawal period, which was presumably due to the resistance selection. Predicted microbial functions associated with genetic information processing were significantly decreased in the high dosage group. Overall

Microbial Shifts in the Intestinal Microbiota of Salmonella Infected Chickens in Response to Enrofloxacin

Directory of Open Access Journals (Sweden)

Jun Li

2017-09-01

Full Text Available Fluoroquinolones (FQs are important antibiotics used for treatment of Salmonella infection in poultry in many countries. However, oral administration of fluoroquinolones may affect the composition and abundance of a number of bacterial taxa in the chicken intestine. Using 16S rRNA gene sequencing, the microbial shifts in the gut of Salmonella infected chickens in response to enrofloxacin treatments at different dosages (0, 0.1, 4, and 100 mg/kg b.w. were quantitatively evaluated. The results showed that the shedding levels of Salmonella were significantly reduced in the high dosage group as demonstrated by both the culturing method and 16S rRNA sequencing method. The average values of diversity indices were higher in the control group than in the three medicated groups. Non-metric multidimensional scaling (NMDS analysis results showed that the microbial community of high dosage group was clearly separated from the other three groups. In total, 25 genera were significantly enriched (including 6 abundant genera: Lactococcus, Bacillus, Burkholderia, Pseudomonas, Rhizobium, and Acinetobacter and 23 genera were significantly reduced in the medicated groups than in the control group for the treatment period, but these bacterial taxa recovered to normal levels after therapy withdrawal. Additionally, 5 genera were significantly reduced in both treatment and withdrawal periods (e.g., Blautia and Anaerotruncus and 23 genera (e.g., Enterobacter and Clostridium were significantly decreased only in the withdrawal period, indicating that these genera might be the potential targets for the fluoroquinolones antimicrobial effects. Specially, Enterococcus was significantly reduced under high dosage of enrofloxacin treatment, while significantly enriched in the withdrawal period, which was presumably due to the resistance selection. Predicted microbial functions associated with genetic information processing were significantly decreased in the high dosage group

Responses of microbial tolerance to heavy metals along a century-old metal ore pollution gradient in a subarctic birch forest.

Science.gov (United States)

Rousk, Johannes; Rousk, Kathrin

2018-05-07

Heavy metals are some of the most persistent and potent anthropogenic environmental contaminants. Although heavy metals may compromise microbial communities and soil fertility, it is challenging to causally link microbial responses to heavy metals due to various confounding factors, including correlated soil physicochemistry or nutrient availability. A solution is to investigate whether tolerance to the pollutant has been induced, called Pollution Induced Community Tolerance (PICT). In this study, we investigated soil microbial responses to a century-old gradient of metal ore pollution in an otherwise pristine subarctic birch forest generated by a railway source of iron ore transportation. To do this, we determined microbial biomass, growth, and respiration rates, and bacterial tolerance to Zn and Cu in replicated distance transects (1 m-4 km) perpendicular to the railway. Microbial biomass, growth and respiration rates were stable across the pollution gradient. The microbial community structure could be distinguished between sampled distances, but most of the variation was explained by soil pH differences, and it did not align with distance from the railroad pollution source. Bacterial tolerance to Zn and Cu started from background levels at 4 km distance from the pollution source, and remained at background levels for Cu throughout the gradient. Yet, bacterial tolerance to Zn increased 10-fold 100 m from the railway source. Our results show that the microbial community structure, size and performance remained unaffected by the metal ore exposure, suggesting no impact on ecosystem functioning. Copyright © 2018 Elsevier Ltd. All rights reserved.

An Alternative Approach to Non-Log-Linear Thermal Microbial Inactivation: Modelling the Number of Log Cycles Reduction with Respect to Temperature

Directory of Open Access Journals (Sweden)

Vasilis Panagiotis Valdramidis

2005-01-01

Full Text Available A mathematical approach incorporating the shoulder effect during the quantification of microbial heat inactivation is being developed based on »the number of log cycles of reduction « concept. Hereto, the heat resistance of Escherichia coli K12 in BHI broth has been quantitatively determined in a generic and accurate way by defining the time t for x log reductions in the microbial population, i.e. txD, as a function of the treatment temperature T. Survival data of the examined microorganism are collected in a range of temperatures between 52–60.6 °C. Shoulder length Sl and specific inactivation rate kmax are derived from a mathematical expression that describes a non-log-linear behaviour. The temperature dependencies of Sl and kmax are used for structuring the txD(T function. Estimation of the txD(T parameters through a global identification procedure permits reliable predictions of the time to achieve a pre-decided microbial reduction. One of the parameters of the txD(T function is proposed as »the reference minimum temperature for inactivation«. For the case study considered, a value of 51.80 °C (with a standard error, SE, of 3.47 was identified. Finally, the time to achieve commercial sterilization and pasteurization for the product at hand, i.e. BHI broth, was found to be 11.70 s (SE=5.22, and 5.10 min (SE=1.22, respectively. Accounting for the uncertainty (based on the 90 % confidence intervals, CI a fail-safe treatment of these two processes takes 20.36 s and 7.12 min, respectively.

Inhibitors degradation and microbial response during continuous anaerobic conversion of hydrothermal liquefaction wastewater.

Science.gov (United States)

Si, Buchun; Li, Jiaming; Zhu, Zhangbing; Shen, Mengmeng; Lu, Jianwen; Duan, Na; Zhang, Yuanhui; Liao, Qiang; Huang, Yun; Liu, Zhidan

2018-07-15

One critical challenge of hydrothermal liquefaction (HTL) is its complex aqueous product, which has a high concentration of organic pollutants (up to 100gCOD/L) and diverse fermentation inhibitors, such as furfural, phenolics and N-heterocyclic compounds. Here we report continuous anaerobic digestion of HTL wastewater via an up-flow anaerobic sludge bed reactor (UASB) and packed bed reactor (PBR). Specifically, we investigated the transformation of fermentation inhibitors and microbial response. GC-MS identified the complete degradation of furfural and 5-hydroxymethylfurfural (5-HMF), and partial degradation (54.0-74.6%) of organic nitrogen and phenolic compounds, including 3-hydroxypyridine, phenol and 4-ethyl-phenol. Illumina MiSeq sequencing revealed that the bacteria families related to detoxification increased in response to the HTL aqueous phase. In addition, the increase of acetate-oxidizing bacteria in UASB and acetogens in PBR showed a strengthened acetogenesis. As for the archaeal communities, an increase in hydrogenotrophic methanogens was observed. Based on GC-MS/HPLC and microbial analysis, we speculate that dominant fermentation inhibitors were transformed into intermediates (Acetyl-CoA and acetate), further contributing to biomethane formation. Copyright © 2018 Elsevier B.V. All rights reserved.

Analyses of soil microbial community compositions and functional genes reveal potential consequences of natural forest succession.

Science.gov (United States)

Cong, Jing; Yang, Yunfeng; Liu, Xueduan; Lu, Hui; Liu, Xiao; Zhou, Jizhong; Li, Diqiang; Yin, Huaqun; Ding, Junjun; Zhang, Yuguang

2015-05-06

The succession of microbial community structure and function is a central ecological topic, as microbes drive the Earth's biogeochemical cycles. To elucidate the response and mechanistic underpinnings of soil microbial community structure and metabolic potential relevant to natural forest succession, we compared soil microbial communities from three adjacent natural forests: a coniferous forest (CF), a mixed broadleaf forest (MBF) and a deciduous broadleaf forest (DBF) on Shennongjia Mountain in central China. In contrary to plant communities, the microbial taxonomic diversity of the DBF was significantly (P the DBF. Furthermore, a network analysis of microbial carbon and nitrogen cycling genes showed the network for the DBF samples was relatively large and tight, revealing strong couplings between microbes. Soil temperature, reflective of climate regimes, was important in shaping microbial communities at both taxonomic and functional gene levels. As a first glimpse of both the taxonomic and functional compositions of soil microbial communities, our results suggest that microbial community structure and function potentials will be altered by future environmental changes, which have implications for forest succession.

Regular Exercise Enhances the Immune Response Against Microbial Antigens Through Up-Regulation of Toll-like Receptor Signaling Pathways

Directory of Open Access Journals (Sweden)

Qishi Zheng

2015-09-01

Full Text Available Background/Aims: Regular physical exercise can enhance resistance to many microbial infections. However, little is known about the mechanism underlying the changes in the immune system induced by regular exercise. Methods: We recruited members of a university badminton club as the regular exercise (RE group and healthy sedentary students as the sedentary control (SC group. We investigated the distribution of peripheral blood mononuclear cell (PBMC subsets and functions in the two groups. Results: There were no significant differences in plasma cytokine levels between the RE and SC groups in the true resting state. However, enhanced levels of IFN-γ, TNF-α, IL-6, IFN-α and IL-12 were secreted by PBMCs in the RE group following microbial antigen stimulation, when compared to the SC group. In contrast, the levels of TNF-α and IL-6 secreted by PBMC in the RE group were suppressed compared with those in SC group following non-microbial antigen stimulation (concanavalin A or α-galactosylceramide. Furthermore, PBMC expression of TLR2, TLR7 and MyD88 was significantly increased in the RE group in response to microbial antigen stimulation. Conclusion: Regular exercise enhances immune cell activation in response to pathogenic stimulation leading to enhanced cytokine production mediated via the TLR signaling pathways.

The effect of temperature change on the microbial diversity and community structure along the chronosequence of the sub-arctic glacier forefield of Styggedalsbreen (Norway).

Science.gov (United States)

Mateos-Rivera, Alejandro; Yde, Jacob C; Wilson, Bryan; Finster, Kai W; Reigstad, Laila J; Øvreås, Lise

2016-04-01

Microbial communities in the glacier forefield of Styggedalsbreen, Norway, were investigated along a chronosequence from newly exposed soil to vegetated soils using next-generation sequencing of the 16S rRNA gene. In order to monitor the short-term effect of temperature on community successions along the soil gradient, the soil samples were incubated at three different temperatures (5°C, 10°C and 22°C). The microbial community composition along the chronosequence differed according to distance from the glacial terminus and incubation temperature. Samples close to the glacier terminus were dominated by Proteobacteria at 5°C and 10°C, while at 22°C members of Chloroflexi, Acidobacteria and Verrucomicrobia in addition to Proteobacteria accounted for most of the diversity, indicating that sites close to the glacier terminus are more closely related to former subglacial environments. Within the Archaea domain, members of the phylum Euryarchaeota dominated in samples closer to the glacier terminus with a shift to members of the phyla Thaumarchaeota-Crenarchaeota with increased soil age. Our data indicate that composition and diversity of the microbial communities along the glacier forefield depend not only on exposure time but are also to a large degree influenced by soil surface temperature and soil maturation. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Cold adaptation and replicable microbial community development during long-term low-temperature anaerobic digestion treatment of synthetic sewage.

Science.gov (United States)

Keating, C; Hughes, D; Mahony, T; Cysneiros, D; Ijaz, U Z; Smith, C J; O'Flaherty, V

2018-07-01

The development and activity of a cold-adapting microbial community was monitored during low-temperature anaerobic digestion (LtAD) treatment of wastewater. Two replicate hybrid anaerobic sludge bed-fixed-film reactors treated a synthetic sewage wastewater at 12°C, at organic loading rates of 0.25-1.0 kg chemical oxygen demand (COD) m-3 d-1, over 889 days. The inoculum was obtained from a full-scale anaerobic digestion reactor, which was operated at 37°C. Both LtAD reactors readily degraded the influent with COD removal efficiencies regularly exceeding 78% for both the total and soluble COD fractions. The biomass from both reactors was sampled temporally and tested for activity against hydrolytic and methanogenic substrates at 12°C and 37°C. Data indicated that significantly enhanced low-temperature hydrolytic and methanogenic activity developed in both systems. For example, the hydrolysis rate constant (k) at 12°C had increased 20-30-fold by comparison to the inoculum by day 500. Substrate affinity also increased for hydrolytic substrates at low temperature. Next generation sequencing demonstrated that a shift in a community structure occurred over the trial, involving a 1-log-fold change in 25 SEQS (OTU-free approach) from the inoculum. Microbial community structure changes and process performance were replicable in the LtAD reactors.

Response of Functional Structure of Soil Microbial Community to Multi-level Nitrogen Additions on the Central Tibetan Plateau

Science.gov (United States)

Zhang, G.; Yuan, Y.

2015-12-01

The use of fossil fuels and fertilizers has increased the amount of biologically reactive nitrogen in the atmosphere over the past century. Tibet is the one of the most threatened regions by nitrogen deposition, thus understanding how its microbial communities function maybe of high importance to predicting microbial responses to nitrogen deposition. Here we describe a short-time nitrogen addition conducted in an alpine steppe ecosystem to investigate the response of functional structure of soil microbial community to multi-level nitrogen addition. Using a GeoChip 4.0, we showed that functional diversities and richness of functional genes were unchanged at low level of nitrogen fertilizer inputs (=40 kg N ha-1 yr-1). Detrended correspondence analysis indicated that the functional structure of microbial communities was markedly different across the nitrogen gradients. Most C degradation genes whose abundances significantly increased under elevated N fertilizer were those involved in the degradation of relatively labile C (starch, hemicellulose, cellulose), whereas the abundance of certain genes involved in the degradation of recalcitrant C (i.e. lignin) was largely decreased (such as manganese peroxidase, mnp). The results suggest that the elevated N fertilization rates might significantly accelerate the labile C degradation, but might not spur recalcitrant C degradation. The combined effect of gdh and ureC genes involved in N cycling appeared to shift the balance between ammonia and organic N toward organic N ammonification and hence increased the N mineralization potential. Moreover, Urease directly involved in urea mineralization significantly increased. Lastly, Canonical correspondence analysis showed that soil (TOC+NH4++NO3-+NO2-+pH) and plant (Aboveground plant productivity + Shannon Diversity) variables could explain 38.9% of the variation of soil microbial community composition. On the basis of above observations, we predict that increasing of nitrogen

Microbial community responses to organophosphate substrate additions in contaminated subsurface sediments.

Directory of Open Access Journals (Sweden)

Robert J Martinez

Full Text Available BACKGROUND: Radionuclide- and heavy metal-contaminated subsurface sediments remain a legacy of Cold War nuclear weapons research and recent nuclear power plant failures. Within such contaminated sediments, remediation activities are necessary to mitigate groundwater contamination. A promising approach makes use of extant microbial communities capable of hydrolyzing organophosphate substrates to promote mineralization of soluble contaminants within deep subsurface environments. METHODOLOGY/PRINCIPAL FINDINGS: Uranium-contaminated sediments from the U.S. Department of Energy Oak Ridge Field Research Center (ORFRC Area 2 site were used in slurry experiments to identify microbial communities involved in hydrolysis of 10 mM organophosphate amendments [i.e., glycerol-2-phosphate (G2P or glycerol-3-phosphate (G3P] in synthetic groundwater at pH 5.5 and pH 6.8. Following 36 day (G2P and 20 day (G3P amended treatments, maximum phosphate (PO4(3- concentrations of 4.8 mM and 8.9 mM were measured, respectively. Use of the PhyloChip 16S rRNA microarray identified 2,120 archaeal and bacterial taxa representing 46 phyla, 66 classes, 110 orders, and 186 families among all treatments. Measures of archaeal and bacterial richness were lowest under G2P (pH 5.5 treatments and greatest with G3P (pH 6.8 treatments. Members of the phyla Crenarchaeota, Euryarchaeota, Bacteroidetes, and Proteobacteria demonstrated the greatest enrichment in response to organophosphate amendments and the OTUs that increased in relative abundance by 2-fold or greater accounted for 9%-50% and 3%-17% of total detected Archaea and Bacteria, respectively. CONCLUSIONS/SIGNIFICANCE: This work provided a characterization of the distinct ORFRC subsurface microbial communities that contributed to increased concentrations of extracellular phosphate via hydrolysis of organophosphate substrate amendments. Within subsurface environments that are not ideal for reductive precipitation of uranium

Soil microbial community structure and nitrogen cycling responses to agroecosystem management and carbon substrate addition

Science.gov (United States)

Berthrong, S. T.; Buckley, D. H.; Drinkwater, L. E.

2011-12-01

Fertilizer application in conventional agriculture leads to N saturation and decoupled soil C and N cycling, whereas organic practices, e.g. complex rotations and legume incorporation, often results in increased SOM and tightly coupled cycles of C and N. These legacy effects of management on soils likely affect microbial community composition and microbial process rates. This project tested if agricultural management practices led to distinct microbial communities and if those communities differed in ability to utilize labile plant carbon substrates and to produce more plant available N. We addressed several specific questions in this project. 1) Do organic and conventional management legacies on similar soils produce distinct soil bacterial and fungal community structures and abundances? 2) How do these microbial community structures change in response to carbon substrate addition? 3) How do the responses of the microbial communities influence N cycling? To address these questions we conducted a laboratory incubation of organically and conventionally managed soils. We added C-13 labelled glucose either in one large dose or several smaller pulses. We extracted genomic DNA from soils before and after incubation for TRFLP community fingerprinting. We measured C in soil pools and respiration and N in soil extracts and leachates. Management led to different compositions of bacteria and fungi driven by distinct components in organic soils. Biomass did not differ across treatments indicating that differences in cycling were due to composition rather than abundance. C substrate addition led to convergence in bacterial communities; however management still strongly influenced the difference in communities. Fungal communities were very distinct between managements and plots with substrate addition not altering this pattern. Organic soils respired 3 times more of the glucose in the first week than conventional soils (1.1% vs 0.4%). Organic soils produced twice as much

Mycobacterial r32-kDa antigen-specific T-cell responses correlate with successful treatment and a heightened anti-microbial response in human leprosy patients.

Science.gov (United States)

Neela, Venkata Sanjeev Kumar; Devalraju, Kamakshi Prudhula; Pydi, Satya Sudheer; Sunder, Sharada Ramaseri; Adiraju, Kameswara Rao; Singh, Surya Satyanarayana; Anandaraj, M P J S; Valluri, Vijaya Lakshmi

2016-09-01

Immunological characterization of mycobacterial peptides may help not only in the preparation of a vaccine for leprosy but also in developing in vitro T-cell assays that could perhaps be used as an in vitro correlate for treatment outcome. The main goal of this study was to evaluate the use of Mycobacterium bovis recombinant 32-kDa protein (r32-kDa) antigen-stimulated T-cell assay as a surrogate marker for treatment outcome and monitor vitamin D receptor (VDR)-mediated anti-microbial responses during multidrug therapy (MDT) in leprosy. Newly diagnosed tuberculoid and lepromatous leprosy patients were enrolled and followed up during their course of MDT at 6 and 12 months. IFN-γ, IL-10, IL-17 and IL-23 levels in culture supernatants and expression of VDR, TLR2, LL37 and DEFB in r32-kDa-stimulated PBMCs were measured. Controls comprised household contacts (HHCs) and healthy endemic subjects (HCs). Significant differences were observed in the levels of IFN-γ, IL-17, IL-23, VDR and anti-microbial peptides LL37 and DEFB after treatment and when compared with that of HHCs and HCs, respectively. These findings suggest that responses to r32-kDa antigen reflect an improved immunological and anti-microbial response in leprosy patients during therapy, thereby indicating its potential use as an immune correlate in the treatment of leprosy patients. © The Japanese Society for Immunology. 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Elucidating Microbial Adaptation Dynamics via Autonomous Exposure and Sampling

Science.gov (United States)

Grace, Joseph M.; Verseux, Cyprien; Gentry, Diana; Moffet, Amy; Thayabaran, Ramanen; Wong, Nathan; Rothschild, Lynn

2013-01-01

The adaptation of micro-organisms to their environments is a complex process of interaction between the pressures of the environment and of competition. Reducing this multifactorial process to environmental exposure in the laboratory is a common tool for elucidating individual mechanisms of evolution, such as mutation rates. Although such studies inform fundamental questions about the way adaptation and even speciation occur, they are often limited by labor-intensive manual techniques. Current methods for controlled study of microbial adaptation limit the length of time, the depth of collected data, and the breadth of applied environmental conditions. Small idiosyncrasies in manual techniques can have large effects on outcomes; for example, there are significant variations in induced radiation resistances following similar repeated exposure protocols. We describe here a project under development to allow rapid cycling of multiple types of microbial environmental exposure. The system allows continuous autonomous monitoring and data collection of both single species and sampled communities, independently and concurrently providing multiple types of controlled environmental pressure (temperature, radiation, chemical presence or absence, and so on) to a microbial community in dynamic response to the ecosystem's current status. When combined with DNA sequencing and extraction, such a controlled environment can cast light on microbial functional development, population dynamics, inter- and intra-species competition, and microbe-environment interaction. The project's goal is to allow rapid, repeatable iteration of studies of both natural and artificial microbial adaptation. As an example, the same system can be used both to increase the pH of a wet soil aliquot over time while periodically sampling it for genetic activity analysis, or to repeatedly expose a culture of bacteria to the presence of a toxic metal, automatically adjusting the level of toxicity based on the

Evaluating the influence of process parameters on soluble microbial products formation using response surface methodology coupled with grey relational analysis.

Science.gov (United States)

Xu, Juan; Sheng, Guo-Ping; Luo, Hong-Wei; Fang, Fang; Li, Wen-Wei; Zeng, Raymond J; Tong, Zhong-Hua; Yu, Han-Qing

2011-01-01

Soluble microbial products (SMPs) present a major part of residual chemical oxygen demand (COD) in the effluents from biological wastewater treatment systems, and the SMP formation is greatly influenced by a variety of process parameters. In this study, response surface methodology (RSM) coupled with grey relational analysis (GRA) method was used to evaluate the effects of substrate concentration, temperature, NH(4)(+)-N concentration and aeration rate on the SMP production in batch activated sludge reactors. Carbohydrates were found to be the major component of SMP, and the influential priorities of these factors were: temperature>substrate concentration > aeration rate > NH(4)(+)-N concentration. On the basis of the RSM results, the interactive effects of these factors on the SMP formation were evaluated, and the optimal operating conditions for a minimum SMP production in such a batch activated sludge system also were identified. These results provide useful information about how to control the SMP formation of activated sludge and ensure the bioreactor high-quality effluent. Copyright © 2010 Elsevier Ltd. All rights reserved.

Microbial Activity Response to Solar Radiation across Contrasting Environmental Conditions in Salar de Huasco, Northern Chilean Altiplano.

Science.gov (United States)

Hernández, Klaudia L; Yannicelli, Beatriz; Olsen, Lasse M; Dorador, Cristina; Menschel, Eduardo J; Molina, Verónica; Remonsellez, Francisco; Hengst, Martha B; Jeffrey, Wade H

2016-01-01

In high altitude environments, extreme levels of solar radiation and important differences of ionic concentrations over narrow spatial scales may modulate microbial activity. In Salar de Huasco, a high-altitude wetland in the Andean mountains, the high diversity of microbial communities has been characterized and associated with strong environmental variability. Communities that differed in light history and environmental conditions, such as nutrient concentrations and salinity from different spatial locations, were assessed for bacterial secondary production (BSP, 3 H-leucine incorporation) response from short-term exposures to solar radiation. We sampled during austral spring seven stations categorized as: (a) source stations, with recently emerged groundwater (no-previous solar exposure); (b) stream running water stations; (c) stations connected to source waters but far downstream from source points; and (d) isolated ponds disconnected from ground sources or streams with a longer isolation and solar exposure history. Very high values of 0.25 μE m -2 s -1 , 72 W m -2 and 12 W m -2 were measured for PAR, UVA, and UVB incident solar radiation, respectively. The environmental factors measured formed two groups of stations reflected by principal component analyses (near to groundwater sources and isolated systems) where isolated ponds had the highest BSP and microbial abundance (35 microalgae taxa, picoeukaryotes, nanoflagellates, and bacteria) plus higher salinities and PO 4 3- concentrations. BSP short-term response (4 h) to solar radiation was measured by 3 H-leucine incorporation under four different solar conditions: full sun, no UVB, PAR, and dark. Microbial communities established in waters with the longest surface exposure (e.g., isolated ponds) had the lowest BSP response to solar radiation treatments, and thus were likely best adapted to solar radiation exposure contrary to ground source waters. These results support our light history (solar exposure

Pyrosequencing reveals high-temperature cellulolytic microbial consortia in Great Boiling Spring after in situ lignocellulose enrichment.

Directory of Open Access Journals (Sweden)

Joseph P Peacock

Full Text Available To characterize high-temperature cellulolytic microbial communities, two lignocellulosic substrates, ammonia fiber-explosion-treated corn stover and aspen shavings, were incubated at average temperatures of 77 and 85°C in the sediment and water column of Great Boiling Spring, Nevada. Comparison of 109,941 quality-filtered 16S rRNA gene pyrosequences (pyrotags from eight enrichments to 37,057 quality-filtered pyrotags from corresponding natural samples revealed distinct enriched communities dominated by phylotypes related to cellulolytic and hemicellulolytic Thermotoga and Dictyoglomus, cellulolytic and sugar-fermenting Desulfurococcales, and sugar-fermenting and hydrogenotrophic Archaeoglobales. Minor enriched populations included close relatives of hydrogenotrophic Thermodesulfobacteria, the candidate bacterial phylum OP9, and candidate archaeal groups C2 and DHVE3. Enrichment temperature was the major factor influencing community composition, with a negative correlation between temperature and richness, followed by lignocellulosic substrate composition. This study establishes the importance of these groups in the natural degradation of lignocellulose at high temperatures and suggests that a substantial portion of the diversity of thermophiles contributing to consortial cellulolysis may be contained within lineages that have representatives in pure culture.

Competition between autotrophic and heterotrophic microbial plankton for inorganic nutrients induced by variability in estuarine biophysicochemical conditions

Science.gov (United States)

Williams, A.; Quigg, A.

2016-02-01

Competition for inorganic nutrients between autotrophic and heterotrophic fractions of microbial plankton (0.2-20μm) was investigated at two stations in a sub-tropical estuary, Galveston Bay, Texas. Competition potential between these groups is enhanced because individuals are similar in size, reducing variability among their nutrient uptake efficiencies. Further, in estuaries, allochthonous supplements to autochthonous carbon may satisfy heterotrophic requirements, allowing alternative factors to limit abundance. The relative abundance of autotrophs and heterotrophs stained with SYBR Green I and enumerated on a Beckman Coulter Gallios flow cytometer were evaluated monthly during a year-long study. Shifts in the relative in situ abundance were significantly related to temperature, dissolved inorganic nitrogen (DIN), phosphorous (Pi), and total organic carbon (TOC) concentrations revealing opposing gradients of limitation by different abiotic factors. In corresponding in vitro nutrient enrichment bioassays the relative contribution of autotrophic or heterotrophic microbial plankton to significant enrichment responses varied. Only during macro- (>20μm) phytoplankton blooms do autotrophic microbial plankton respond to nutrient enrichment. Contrastingly, the heterotrophic microbial plankton responded to nutrient enrichment primarily when temperature limitation was alleviated. Therefore, the potential for autotrophic and heterotrophic microbial plankton competition for limiting nutrients is highest when autotrophic microbial plankton are also competing with larger phytoplankton during bloom events. Based on this evidence, we hypothesize that the autotrophic microbial fraction has a competitive advantage over the heterotrophs for inorganic nutrients in Galveston Bay. The observed microbial competition during estuarine phytoplankton blooms may have important consequences on biogeochemical processes including carbon and nutrient cycling.

Reduced neonatal regulatory T cell response to microbial stimuli associates with subsequent eczema in high-risk infants.

Science.gov (United States)

Ismail, Intan H; Boyle, Robert J; Mah, Li-Jeen; Licciardi, Paul V; Tang, Mimi L K

2014-11-01

Regulatory T cells (Treg) play an essential role in early immune programming and shaping the immune response towards a pro-allergic or tolerant state. We evaluated cord blood Treg and cytokine responses to microbial and non-microbial stimuli in infants at high risk of allergic disease and their associations with development of allergic disease in the first year. Cord blood mononuclear cells from 72 neonates were cultured with toll-like receptors (TLR2) ligands: lipoteichoic acid (LTA) and heat-killed Lactobacillus rhamnosus GG (HKL); TLR4 ligand: lipopolysaccharide (LPS); ovalbumin (OVA); anti-CD3; or media for 48 h. Treg numbers and Treg cytokines were assessed in relation to allergic disease outcomes during the first year of life (eczema and atopic sensitization). Infants with eczema (n = 24) had reduced percentages of FoxP3(hi)CD25(hi) Treg in LTA (p = 0.01, adj p = 0.005) and HKL (p = 0.04, adj p = 0.02) stimulated cultures as well as reduced IL-10 (p = 0.01) production following HKL stimulation compared to those without eczema (n = 48). No differences in Treg or cytokine responses to LPS, OVA or anti-CD3 were seen. Infants who developed sensitization had lower percentages of Treg following TLR2 stimulation (but not other stimuli) compared to non-sensitized infants. High-risk children who develop allergic disease in the first year of life have deficient Treg responses to microbial stimuli but not allergen from the time of birth, which may contribute to failure of immune tolerance development in infancy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Detrital floc and surface soil microbial biomarker responses to active management of the nutrient impacted Florida everglades.

Science.gov (United States)

Bellinger, Brent J; Hagerthey, Scot E; Newman, Susan; Cook, Mark I

2012-11-01

Alterations in microbial community composition, biomass, and function in the Florida Everglades impacted by cultural eutrophication reflect a new physicochemical environment associated with monotypic stands of Typha domingensis. Phospholipid fatty acid (PLFA) biomarkers were used to quantify microbial responses in detritus and surface soils in an active management experiment in the eutrophic Everglades. Creation of open plots through removal of Typha altered the physical and chemical characteristics of the region. Mass of PLFA biomarkers increased in open plots, but magnitude of changes differed among microbial groups. Biomarkers indicative of Gram-negative bacteria and fungi were significantly greater in open plots, reflective of the improved oxic environment. Reduction in the proportion of cyclopropyl lipids and the ratio of Gram-positive to Gram-negative bacteria in open plots further suggested an altered oxygen environment and conditions for the rapid growth of Gram-negative bacteria. Changes in the PLFA composition were greater in floc relative to soils, reflective of rapid inputs of new organic matter and direct interaction with the new physicochemical environment. Created open plot microbial mass and composition were significantly different from the oligotrophic Everglades due to differences in phosphorus availability, plant community structure, and a shift to organic peat from marl-peat soils. PLFA analysis also captured the dynamic inter-annual hydrologic variability, notably in PLFA concentrations, but to a lesser degree content. Recently, use of concentration has been advocated over content in studies of soil biogeochemistry, and our results highlight the differential response of these two quantitative measures to similar pressures.

Distinct respiratory responses of soils to complex organic substrate are governed predominantly by soil architecture and its microbial community.

Science.gov (United States)

Fraser, F C; Todman, L C; Corstanje, R; Deeks, L K; Harris, J A; Pawlett, M; Whitmore, A P; Ritz, K

2016-12-01

Factors governing the turnover of organic matter (OM) added to soils, including substrate quality, climate, environment and biology, are well known, but their relative importance has been difficult to ascertain due to the interconnected nature of the soil system. This has made their inclusion in mechanistic models of OM turnover or nutrient cycling difficult despite the potential power of these models to unravel complex interactions. Using high temporal-resolution respirometery (6 min measurement intervals), we monitored the respiratory response of 67 soils sampled from across England and Wales over a 5 day period following the addition of a complex organic substrate (green barley powder). Four respiratory response archetypes were observed, characterised by different rates of respiration as well as different time-dependent patterns. We also found that it was possible to predict, with 95% accuracy, which type of respiratory behaviour a soil would exhibit based on certain physical and chemical soil properties combined with the size and phenotypic structure of the microbial community. Bulk density, microbial biomass carbon, water holding capacity and microbial community phenotype were identified as the four most important factors in predicting the soils' respiratory responses using a Bayesian belief network. These results show that the size and constitution of the microbial community are as important as physico-chemical properties of a soil in governing the respiratory response to OM addition. Such a combination suggests that the 'architecture' of the soil, i.e. the integration of the spatial organisation of the environment and the interactions between the communities living and functioning within the pore networks, is fundamentally important in regulating such processes.

Differential Responses of Soil Microbial Community to Four-Decade Long Grazing and Cultivation in a Semi-Arid Grassland

Directory of Open Access Journals (Sweden)

Yating He

2017-01-01

Full Text Available Grazing and cultivation are two important management practices worldwide that can cause significant soil organic carbon (SOC losses. However, it remains elusive how soil microbes have responded to soil carbon changes under these two practices. Based on a four-decade long field experiment, this study investigated the effects of grazing and cultivation on SOC stocks and microbial properties in the semi-arid grasslands of China. We hypothesize that grazing and cultivation would deplete SOC and depress microbial activities under both practices. However, our hypotheses were only partially supported. As compared with the adjacent indigenous grasslands, SOC and microbial biomass carbon (MBC were decreased by 20% or more under grazing and cultivation, which is consistent with the reduction of fungi abundance by 40% and 71%, respectively. The abundance of bacteria and actinomycetes was decreased under grazing but increased under cultivation, which likely enhanced microbial diversity in cultivation. Invertase activity decreased under the two treatments, while urease activity increased under grazing. These results suggest that nitrogen fertilizer input during cultivation may preferentially favor bacterial growth, in spite of SOC loss, due to rapid decomposition, while overgrazing may deteriorate the nitrogen supply to belowground microbes, thus stimulating the microbial production of nitrogen acquisition enzymes. This decade-long study demonstrated differential soil microbial responses under grazing and cultivation and has important applications for better management practices in the grassland ecosystem.

Quantifying the Importance of the Rare Biosphere for Microbial Community Response to Organic Pollutants in a Freshwater Ecosystem.

Science.gov (United States)

Wang, Yuanqi; Hatt, Janet K; Tsementzi, Despina; Rodriguez-R, Luis M; Ruiz-Pérez, Carlos A; Weigand, Michael R; Kizer, Heidi; Maresca, Gina; Krishnan, Raj; Poretsky, Rachel; Spain, Jim C; Konstantinidis, Konstantinos T

2017-04-15

A single liter of water contains hundreds, if not thousands, of bacterial and archaeal species, each of which typically makes up a very small fraction of the total microbial community (biosphere." How often, and via what mechanisms, e.g., clonal amplification versus horizontal gene transfer, the rare taxa and genes contribute to microbial community response to environmental perturbations represent important unanswered questions toward better understanding the value and modeling of microbial diversity. We tested whether rare species frequently responded to changing environmental conditions by establishing 20-liter planktonic mesocosms with water from Lake Lanier (Georgia, USA) and perturbing them with organic compounds that are rarely detected in the lake, including 2,4-dichlorophenoxyacetic acid (2,4-D), 4-nitrophenol (4-NP), and caffeine. The populations of the degraders of these compounds were initially below the detection limit of quantitative PCR (qPCR) or metagenomic sequencing methods, but they increased substantially in abundance after perturbation. Sequencing of several degraders (isolates) and time-series metagenomic data sets revealed distinct cooccurring alleles of degradation genes, frequently carried on transmissible plasmids, especially for the 2,4-D mesocosms, and distinct species dominating the post-enrichment microbial communities from each replicated mesocosm. This diversity of species and genes also underlies distinct degradation profiles among replicated mesocosms. Collectively, these results supported the hypothesis that the rare biosphere can serve as a genetic reservoir, which can be frequently missed by metagenomics but enables community response to changing environmental conditions caused by organic pollutants, and they provided insights into the size of the pool of rare genes and species. IMPORTANCE A single liter of water or gram of soil contains hundreds of low-abundance bacterial and archaeal species, the so called rare biosphere. The

Forest ecotone response to climate change: sensitivity to temperature response functional forms

Energy Technology Data Exchange (ETDEWEB)

Loehle, C. [National Council for Air and Stream Improvement, Naperville, IL (United States)

2000-10-01

Past simulation studies have been in general agreement that climatic change could have adverse effects on forests, including geographic range shrinkages, conversion to grassland, and catastrophic forest decline or dieback. Some other recent studies, however, concluded that this agreement is generally based on parabolic temperature response rather than functional responses or data, and may therefore exaggerate dieback effects. This paper proposes a new model of temperature response that is based on a trade-off between cold tolerance and growth rate. In this model, the growth rate increases at first, and then levels off with increasing growing degree-days. Species from more southern regions have a higher minimum temperature and a faster maximum height growth rate. It is argued that faster growth rates of southern types lead to their competitive superiority in warmer environments and that such temperature response should produce less dieback and slower rates of change than the more common parabolic response model. Theoretical justification of this model is provided, followed by application of the model to a simulated ecotone under a warming scenario. Results of the study based on the proposed asymptotic model showed no dieback and only a gradual ecotone movement north, suggesting that ecotone shifts will, in fact, take many hundreds to thousands of years, with the result that species will not face the risk of extinction. 56 refs., 1 tab., 8 figs.

Distinct responses of soil microbial communities to elevated CO2 and O3 in a soybean agro-ecosystem.

Science.gov (United States)

He, Zhili; Xiong, Jinbo; Kent, Angela D; Deng, Ye; Xue, Kai; Wang, Gejiao; Wu, Liyou; Van Nostrand, Joy D; Zhou, Jizhong

2014-03-01

The concentrations of atmospheric carbon dioxide (CO2) and tropospheric ozone (O3) have been rising due to human activities. However, little is known about how such increases influence soil microbial communities. We hypothesized that elevated CO2 (eCO2) and elevated O3 (eO3) would significantly affect the functional composition, structure and metabolic potential of soil microbial communities, and that various functional groups would respond to such atmospheric changes differentially. To test these hypotheses, we analyzed 96 soil samples from a soybean free-air CO2 enrichment (SoyFACE) experimental site using a comprehensive functional gene microarray (GeoChip 3.0). The results showed the overall functional composition and structure of soil microbial communities shifted under eCO2, eO3 or eCO2+eO3. Key functional genes involved in carbon fixation and degradation, nitrogen fixation, denitrification and methane metabolism were stimulated under eCO2, whereas those involved in N fixation, denitrification and N mineralization were suppressed under eO3, resulting in the fact that the abundance of some eO3-supressed genes was promoted to ambient, or eCO2-induced levels by the interaction of eCO2+eO3. Such effects appeared distinct for each treatment and significantly correlated with soil properties and soybean yield. Overall, our analysis suggests possible mechanisms of microbial responses to global atmospheric change factors through the stimulation of C and N cycling by eCO2, the inhibition of N functional processes by eO3 and the interaction by eCO2 and eO3. This study provides new insights into our understanding of microbial functional processes in response to global atmospheric change in soybean agro-ecosystems.

Phenotypic responses to interspecies competition and commensalism in a naturally-derived microbial co-culture

Energy Technology Data Exchange (ETDEWEB)

Khan, Nymul; Maezato, Yukari; McClure, Ryan S.; Brislawn, Colin J.; Mobberley, Jennifer M.; Isern, Nancy; Chrisler, William B.; Markillie, Lye Meng; Barney, Brett M.; Song, Hyun-Seob; Nelson, William C.; Bernstein, Hans C.

2018-01-10

The fundamental question of whether different microbial species will co-exist or compete in a given environment depends on context, composition and environmental constraints. Model microbial systems can yield some general principles related to this question. In this study we employed a naturally occurring co-culture composed of heterotrophic bacteria, Halomonas sp. HL-48 and Marinobacter sp. HL-58, to ask two fundamental scientific questions: 1) how do the phenotypes of two naturally co-existing species respond to partnership as compared to axenic growth? and 2) how do growth and molecular phenotypes of these species change with respect to competitive and commensal interactions? We hypothesized – and confirmed – that co-cultivation under glucose as the sole carbon source would result in a competitive interactions. Similarly, when glucose was swapped with xylose, the interactions became commensal because Marinobacter HL-58 was supported by metabolites derived from Halomonas HL-48. Each species responded to partnership by changing both its growth and molecular phenotype as assayed via batch growth kinetics and global transcriptomics. These phenotypic responses depended nutrient availability and so the environment ultimately controlled how they responded to each other. This simplified model community revealed that microbial interactions are context-specific and different environmental conditions dictate how interspecies partnerships will unfold.

Compositional differences in simulated root exudates elicit a limited functional and compositional response in soil microbial communities.

Science.gov (United States)

Strickland, Michael S; McCulley, Rebecca L; Nelson, Jim A; Bradford, Mark A

2015-01-01

Inputs of low molecular weight carbon (LMW-C) to soil - primarily via root exudates- are expected to be a major driver of microbial activity and source of stable soil organic carbon. It is expected that variation in the type and composition of LMW-C entering soil will influence microbial community composition and function. If this is the case then short-term changes in LMW-C inputs may alter processes regulated by these communities. To determine if change in the composition of LMW-C inputs influences microbial community function and composition, we conducted a 90 day microcosm experiment whereby soils sourced from three different land covers (meadows, deciduous forests, and white pine stands) were amended, at low concentrations, with one of eight simulated root exudate treatments. Treatments included no addition of LMW-C, and the full factorial combination of glucose, glycine, and oxalic acid. After 90 days, we conducted a functional response assay and determined microbial composition via phospholipid fatty acid analysis. Whereas we noted a statistically significant effect of exudate treatments, this only accounted for ∼3% of the variation observed in function. In comparison, land cover and site explained ∼46 and ∼41% of the variation, respectively. This suggests that exudate composition has little influence on function compared to site/land cover specific factors. Supporting the finding that exudate effects were minor, we found that an absence of LMW-C elicited the greatest difference in function compared to those treatments receiving any LMW-C. Additionally, exudate treatments did not alter microbial community composition and observable differences were instead due to land cover. These results confirm the strong effects of land cover/site legacies on soil microbial communities. In contrast, short-term changes in exudate composition, at meaningful concentrations, may have little impact on microbial function and composition.

Review of microbial responses to abiotic environmental factors in the context of the proposed Yucca Mountain repository

Energy Technology Data Exchange (ETDEWEB)

Meike, A [Lawrence Livermore National Lab., Livermore, CA (United States); Stroes-Gascoyne, S

2000-10-01

second, that modified environment would then be perturbed by the radioactive waste itself during the lifetime of the repository (heat, redistribution of moisture and possibly radioactivity. Part Two (Chapters 4, 5 and 6) discusses the microbial capabilities established in part one, in a site specific framework that will help define the limits of expected microbial activity. The expected evolution of a potential repository at Yucca Mountain is reviewed as well as those factors identified to be potential issues to microbial activity (i.e., high temperatures, changes in pH, desiccation, salinity changes and radiation). Expectations for microbial activity, where possible in the context of explicit input to design decisions for the proposed Yucca Mountain Repository, are discussed. (author)

Review of microbial responses to abiotic environmental factors in the context of the proposed Yucca Mountain repository

Energy Technology Data Exchange (ETDEWEB)

Meike, A. [Lawrence Livermore National Lab., Livermore, CA (United States); Stroes-Gascoyne, S

2000-10-01

repository and second, that modified environment would then be perturbed by the radioactive waste itself during the lifetime of the repository (heat, redistribution of moisture and possibly radioactivity. Part Two (Chapters 4, 5 and 6) discusses the microbial capabilities established in part one, in a site specific framework that will help define the limits of expected microbial activity. The expected evolution of a potential repository at Yucca Mountain is reviewed as well as those factors identified to be potential issues to microbial activity (i.e., high temperatures, changes in pH, desiccation, salinity changes and radiation). Expectations for microbial activity, where possible in the context of explicit input to design decisions for the proposed Yucca Mountain Repository, are discussed. (author)

Investigation of extractive microbial transformation in nonionic surfactant micelle aqueous solution using response surface methodology.

Science.gov (United States)

Xue, Yingying; Qian, Chen; Wang, Zhilong; Xu, Jian-He; Yang, Rude; Qi, Hanshi

2010-01-01

Extractive microbial transformation of L-phenylacetylcarbinol (L-PAC) in nonionic surfactant Triton X-100 micelle aqueous solution was investigated by response surface methodology. Based on the Box-Behnken design, a mathematical model was developed for the predication of mutual interactions between benzaldehyde, Triton X-100, and glucose on L-PAC production. It indicated that the negative or positive effect of nonionic surfactant strongly depended on the substrate concentration. The model predicted that the optimal concentration of benzaldehyde, Triton X-100, and glucose was 1.2 ml, 15 g, and 2.76 g per 100 ml, respectively. Under the optimal condition, the maximum L-PAC production was 27.6 mM, which was verified by a time course of extractive microbial transformation. A discrete fed-batch process for verification of cell activity was also presented.

Effect of environmental conditions on the fatty acid fingerprint of microbial communities

Science.gov (United States)

Biryukov, Mikhail; Dippold, Michaela; Kuzyakov, Yakov

2014-05-01

Lipid biomarkers, especially phospholipids, are routinely used to characterize microbial community structure in environmental samples. Interpretations of these fingerprints mainly depend on rare results of pure cultures which were cultivated under standardized batch conditions. However, membrane lipids (e.g. phopholipid biomarker) build up the interface between microorganisms and their environment and consequently are prone to be adapted according to the environmental conditions. We cultivated several bacteria, isolated from soil (gram-positive and gram-negative) under various conditions e.g. C supply and temperature regimes. Effect of growth conditions on phospholipids fatty acid (PLFA) as well as neutral lipid fatty acids (NLFA) and glycolipid fatty acids (GLFA) was investigated by conventional method of extraction and derivatization, followed by assessments with gas chromatography mass spectrometry (GC-MS). In addition, phospholipids were measured as intact molecules by ultra high performance liquid chromatography - quadrupole - time of flight mass spectrometer (UHPLC-Q-ToF) to further assess the composition of headgroups with fatty acids residues and their response on changing environmental conditions. PLFA fingerprints revealed a strong effect of growth stage, C supply and temperature e.g. decrease of temperature increased the amount of branched and/or unsaturated fatty acids to maintain the membrane fluidity. This strongly changes the ratio of specific to unspecific fatty acids depending on environmental conditions. Therefore, amounts of specific fatty acids cannot be used to assess biomass of a functional microbial group in soil. Intracellular neutral lipids depended less on environmental conditions reflecting a more stable biomarker group but also showed less specific fatty acids then PLFA. Therefore, combination of several lipid classes is suggested as more powerful tool to assess amounts and functionality of environmental microbial communities. Further

Microbial DNA; a possible tracer of groundwater

Science.gov (United States)

Sugiyama, Ayumi; Segawa, Takuya; Furuta, Tsuyumi; Nagaosa, Kazuyo; Tsujimura, Maki; Kato, Kenji

2017-04-01

Though chemical analysis of groundwater shows an averaged value of chemistry of the examined water which was blended by various water with different sources and routes in subsurface environment, microbial DNA analysis may suggest the place where they originated, which may give information of the source and transport routes of the water examined. A huge amount of groundwater is stored in lava layer with maximum depth of 300m in Mt. Fuji (3,776m asl ), the largest volcanic mountain in Japan. Although the density of prokaryotes was low in the examined groundwater of Mt. Fuji, thermophilic prokaryotes as Thermoanaerobacterales, Gaiellales and Thermoplasmatales were significantly detected. They are optimally adapted to the temperature higher than 40oC. This finding suggests that at least some of the source of the examined groundwater was subsurface environment with 600m deep or greater, based on a temperature gradient of 4oC/100m and temperature of spring water ranges from 10 to 15oC in the foot of Mt. Fuji. This depth is far below the lava layer. Thus, the groundwater is not simply originated from the lava layer. In addition to those findings, we observed a very fast response of groundwater just a couple of weeks after the heavy rainfall exceeding 2 or 300 mm/event in Mt. Fuji. The fast response was suggested by a sharp increase in bacterial abundance in spring water located at 700m in height in the west foot of Mt. Fuji, where the average recharge elevation of groundwater was estimated to be 1,500m - 1,700m (Kato et. al. EGU 2016). This increase was mainly provided by soil bacteria as Burkholderiales, which might be detached from soil by strengthened subsurface flow caused by heavy rainfall. This suggests that heavy rainfall promotes shallow subsurface flow contributing to the discharge in addition to the groundwater in the deep aquifer. Microbial DNA, thus could give information about the route of the examined groundwater, which was never elucidated by analysis of

Soil respiration fluxes in a temperate mixed forest: seasonality and temperature sensitivities differ among microbial and root-rhizosphere respiration.

Science.gov (United States)

Ruehr, Nadine K; Buchmann, Nina

2010-02-01

Although soil respiration, a major CO(2) flux in terrestrial ecosystems, is known to be highly variable with time, the response of its component fluxes to temperature and phenology is less clear. Therefore, we partitioned soil respiration (SR) into microbial (MR) and root-rhizosphere respiration (RR) using small root exclusion treatments in a mixed mountain forest in Switzerland. In addition, fine root respiration (FRR) was determined with measurements of excised roots. RR and FRR were strongly related to each other (R(2) = 0.92, n = 7), with RR contributing about 46% and FRR about 32% to total SR. RR rates increased more strongly with temperature (Q(10) = 3.2) than MR rates (Q(10) = 2.3). Since the contribution of RR to SR was found to be higher during growing (50%) than during dormant periods (40%), we separated the 2-year data set into phenophases. During the growing period of 2007, the temperature sensitivity of RR (Q(10) = 2.5, R(2) = 0.62) was similar to that of MR (Q(10) = 2.2, R(2) = 0.57). However, during the dormant period of 2006/2007, RR was not related to soil temperature (R(2) = 0.44, n.s.), in contrast to MR (Q(10) = 7.2; R(2) = 0.92). To better understand the influence of plant activity on root respiration, we related RR and FRR rates to photosynthetic active radiation (both R(2) = 0.67, n = 7, P = 0.025), suggesting increased root respiration rates during times with high photosynthesis. During foliage green-up in spring 2008, i.e., from bud break to full leaf expansion, RR increased by a factor of 5, while soil temperature increased only by about 5 degrees C, leading to an extraordinary high Q(10) of 10.6; meanwhile, the contribution of RR to SR increased from 29 to 47%. This clearly shows that root respiration and its apparent temperature sensitivity highly depend on plant phenology and thus on canopy assimilation and carbon allocation belowground.

Coral microbial community dynamics in response to anthropogenic impacts near a major city in the central Red Sea

KAUST Repository

Ziegler, Maren; Roik, Anna Krystyna; Porter, Adam; Zubier, Khalid; Mudarris, Mohammed S.; Ormond, Rupert; Voolstra, Christian R.

2016-01-01

Coral-associated bacteria play an increasingly recognized part in coral health. We investigated the effect of local anthropogenic impacts on coral microbial communities on reefs near Jeddah, the largest city on the Saudi Arabian coast of the central Red Sea. We analyzed the bacterial community structure of water and corals (Pocillopora verrucosa and Acropora hemprichii) at sites that were relatively unimpacted, exposed to sedimentation & local sewage, or in the discharge area of municipal wastewaters. Coral microbial communities were significantly different at impacted sites: in both corals the main symbiotic taxon decreased in abundance. In contrast, opportunistic bacterial families, such as e.g. Vibrionaceae and Rhodobacteraceae, were more abundant in corals at impacted sites. In conclusion, microbial community response revealed a measurable footprint of anthropogenic impacts to coral ecosystems close to Jeddah, even though the corals appeared visually healthy.

Coral microbial community dynamics in response to anthropogenic impacts near a major city in the central Red Sea

KAUST Repository

Ziegler, Maren

2016-01-04

Coral-associated bacteria play an increasingly recognized part in coral health. We investigated the effect of local anthropogenic impacts on coral microbial communities on reefs near Jeddah, the largest city on the Saudi Arabian coast of the central Red Sea. We analyzed the bacterial community structure of water and corals (Pocillopora verrucosa and Acropora hemprichii) at sites that were relatively unimpacted, exposed to sedimentation & local sewage, or in the discharge area of municipal wastewaters. Coral microbial communities were significantly different at impacted sites: in both corals the main symbiotic taxon decreased in abundance. In contrast, opportunistic bacterial families, such as e.g. Vibrionaceae and Rhodobacteraceae, were more abundant in corals at impacted sites. In conclusion, microbial community response revealed a measurable footprint of anthropogenic impacts to coral ecosystems close to Jeddah, even though the corals appeared visually healthy.

Responses of Soil Microbial Community Structure and Diversity to Agricultural Deintensification

Institute of Scientific and Technical Information of China (English)

ZHANG Wei-Jian; S.HU; RUI Wen-Yi; C.TU; H.G.DIAB; F.J.LOUWS; J.P.MUELLER; N.CREAMER; M.BELL; M.G.WAGGER

2005-01-01

Using a scheme of agricultural fields with progressively less intensive management (deintensification), different management practices in six agroecosystems located near Goldsboro, NC, USA were tested in a large-scale experiment, including two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT), an organic farming system (OR), an integrated cropping system with animals (IN), a successional field (SU), and a plantation woodlot (WO). Microbial phospholipid fatty acid (PLFA) profiles and substrate utilization patterns (BIOLOG ECO plates) were measured to examine the effects of deintensification on the structure and diversity of soil microbial communities. Principle component analyses of PLFA and BIOLOG data showed that the microbial community structure diverged among the soils of the six systems.Lower microbial diversity was found in lowly managed ecosystem than that in intensive and moderately managed agroecosystems, and both fungal contribution to the total identified PLFAs and the ratio of microbial biomass C/N increased along with agricultural deintensification. Significantly higher ratios of C/N (P ＜ 0.05) were found in the WO and SU systems, and for fungal/bacterial PLFAs in the WO system (P ＜ 0.05). There were also significant decreases (P ＜ 0.05)along with agricultural deintensification for contributions of total bacterial and gram positive (G+) bacterial PLFAs.Agricultural deintensification could facilitate the development of microbial communities that favor soil fungi over bacteria.

Stream microbial diversity responds to environmental changes: Review and synthesis of existing research

Directory of Open Access Journals (Sweden)

Lydia eZeglin

2015-05-01

Full Text Available The importance of microbial activity to ecosystem function in aquatic ecosystems is well established, but microbial diversity has been less frequently addressed. This review and synthesis of the hundreds of published studies on stream microbial diversity shows that factors known to drive ecosystem processes, such as nutrient availability, hydrology, metal contamination, contrasting land-use and temperature, also cause heterogeneity in bacterial diversity. Temporal heterogeneity in stream bacterial diversity was frequently observed, reflecting the dynamic nature of both stream ecosystems and microbial community composition. However, within-stream spatial differences in stream bacterial diversity were more commonly observed, driven specifically by different organic matter compartments. Bacterial phyla showed similar patterns in relative abundance with regard to compartment type across different streams. For example, surface water contained the highest relative abundance of Actinobacteria, while epilithon contained the highest relative abundance of Cyanobacteria and Bacteroidetes. This suggests that contrasting physical and/or nutritional habitats characterized by different stream organic matter compartment types may select for certain bacterial lineages. When comparing the prevalence of physicochemical effects on stream bacterial diversity, effects of changing metal concentrations were most, while effects of differences in nutrient concentrations were least frequently observed. This may indicate that although changing nutrient concentrations do tend to affect microbial diversity, other environmental factors are more likely to alter stream microbial diversity and function. The common observation of connections between ecosystem process drivers and microbial diversity suggests that microbial taxonomic turnover could mediate ecosystem-scale responses to changing environmental conditions, including both microbial habitat distribution and

Temperature response of soil respiration largely unaltered with experimental warming

Science.gov (United States)

Carey, Joanna C.; Tang, Jianwu; Templer, Pamela H.; Kroeger, Kevin D.; Crowther, Thomas W.; Burton, Andrew J.; Dukes, Jeffrey S.; Emmett, Bridget; Frey, Serita D.; Heskel, Mary A.; Jiang, Lifen; Machmuller, Megan B.; Mohan, Jacqueline; Panetta, Anne Marie; Reich, Peter B.; Reinsch, Sabine; Wang, Xin; Allison, Steven D.; Bamminger, Chris; Bridgham, Scott; Collins, Scott L.; de Dato, Giovanbattista; Eddy, William C.; Enquist, Brian J.; Estiarte, Marc; Harte, John; Henderson, Amanda; Johnson, Bart R.; Steenberg Larsen, Klaus; Luo, Yiqi; Marhan, Sven; Melillo, Jerry M.; Penuelas, Josep; Pfeifer-Meister, Laurel; Poll, Christian; Rastetter, Edward B.; Reinmann, Andrew B.; Reynolds, Lorien L.; Schmidt, Inger K.; Shaver, Gaius R.; Strong, Aaron L.; Suseela, Vidya; Tietema, Albert

2016-01-01

The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

Overfishing and nutrient pollution interact with temperature to disrupt coral reefs down to microbial scales.

Science.gov (United States)

Zaneveld, Jesse R; Burkepile, Deron E; Shantz, Andrew A; Pritchard, Catharine E; McMinds, Ryan; Payet, Jérôme P; Welsh, Rory; Correa, Adrienne M S; Lemoine, Nathan P; Rosales, Stephanie; Fuchs, Corinne; Maynard, Jeffrey A; Thurber, Rebecca Vega

2016-06-07

Losses of corals worldwide emphasize the need to understand what drives reef decline. Stressors such as overfishing and nutrient pollution may reduce resilience of coral reefs by increasing coral-algal competition and reducing coral recruitment, growth and survivorship. Such effects may themselves develop via several mechanisms, including disruption of coral microbiomes. Here we report the results of a 3-year field experiment simulating overfishing and nutrient pollution. These stressors increase turf and macroalgal cover, destabilizing microbiomes, elevating putative pathogen loads, increasing disease more than twofold and increasing mortality up to eightfold. Above-average temperatures exacerbate these effects, further disrupting microbiomes of unhealthy corals and concentrating 80% of mortality in the warmest seasons. Surprisingly, nutrients also increase bacterial opportunism and mortality in corals bitten by parrotfish, turning normal trophic interactions deadly for corals. Thus, overfishing and nutrient pollution impact reefs down to microbial scales, killing corals by sensitizing them to predation, above-average temperatures and bacterial opportunism.

Interactions Between Stress and Sex in Microbial Responses Within the Microbiota-Gut-Brain Axis in a Mouse Model.

Science.gov (United States)

Tsilimigras, Matthew C B; Gharaibeh, Raad Z; Sioda, Michael; Gray, Laura; Fodor, Anthony A; Lyte, Mark

2018-05-01

Animal models are frequently used to examine stress response, but experiments seldom include females. The connection between the microbiota-gut-brain axis and behavioral stress response is investigated here using a mixed-sex mouse cohort. CF-1 mice underwent alternating days of restraint and forced swim for 19 days (male n = 8, female n = 8) with matching numbers of control animals at which point the 16S rRNA genes of gut microbiota were sequenced. Mixed linear models accounting for stress status and sex with individuals nested in cage to control for cage effects evaluated these data. Murine behaviors in elevated plus-maze, open-field, and light/dark box were investigated. Community-level associations with sex, stress, and their interaction were significant. Males had higher microbial diversity than females (p = .025). Of the 638 operational taxonomic units detected in at least 25% of samples, 94 operational taxonomic units were significant: 31 (stress), 61 (sex), and 34 (sex-stress interaction). Twenty of the 39 behavioral measures were significant for stress, 3 for sex, and 6 for sex-stress. However, no significant associations between behavioral measures and specific microbes were detected. These data suggest sex influences stress response and the microbiota-gut-brain axis and that studies of behavior and the microbiome therefore benefit from consideration of how sex differences drive behavior and microbial community structure. Host stress resilience and absence of associations between stress-induced behaviors with specific microbes suggests that hypothalamic-pituitary-adrenal axis activation represents a threshold for microbial influence on host behavior. Future studies are needed in examining the intersection of sex, stress response, and the microbiota-gut-brain axis.

Modulation of neonatal microbial recognition: TLR-mediated innate immune responses are specifically and differentially modulated by human milk.

Science.gov (United States)

LeBouder, Emmanuel; Rey-Nores, Julia E; Raby, Anne-Catherine; Affolter, Michael; Vidal, Karine; Thornton, Catherine A; Labéta, Mario O

2006-03-15

The mechanisms controlling innate microbial recognition in the neonatal gut are still to be fully understood. We have sought specific regulatory mechanisms operating in human breast milk relating to TLR-mediated microbial recognition. In this study, we report a specific and differential modulatory effect of early samples (days 1-5) of breast milk on ligand-induced cell stimulation via TLRs. Although a negative modulation was exerted on TLR2 and TLR3-mediated responses, those via TLR4 and TLR5 were enhanced. This effect was observed in human adult and fetal intestinal epithelial cell lines, monocytes, dendritic cells, and PBMC as well as neonatal blood. In the latter case, milk compensated for the low capacity of neonatal plasma to support responses to LPS. Cell stimulation via the IL-1R or TNFR was not modulated by milk. This, together with the differential effect on TLR activation, suggested that the primary effect of milk is exerted upstream of signaling proximal to TLR ligand recognition. The analysis of TLR4-mediated gene expression, used as a model system, showed that milk modulated TLR-related genes differently, including those coding for signal intermediates and regulators. A proteinaceous milk component of > or =80 kDa was found to be responsible for the effect on TLR4. Notably, infant milk formulations did not reproduce the modulatory activity of breast milk. Together, these findings reveal an unrecognized function of human milk, namely, its capacity to influence neonatal microbial recognition by modulating TLR-mediated responses specifically and differentially. This in turn suggests the existence of novel mechanisms regulating TLR activation.

Microbial kinetic for In-Storage-Psychrophilic Anaerobic Digestion (ISPAD).

Science.gov (United States)

Madani-Hosseini, Mahsa; Mulligan, Catherine N; Barrington, Suzelle

2014-12-15

In-Storage-Psychrophilic-Anaerobic-Digestion (ISPAD) is a wastewater storage tank converted into an anaerobic digestion (AD) system by means of an airtight floating geo-membrane. For process optimization, ISPAD requires modelling with well-established microbial kinetics coefficients. The present objectives were to: obtain kinetics coefficients for the modelling of ISPAD; compare the prediction of the conventional and decomposition fitting approach, an innovative fitting technique used in other fields of science, and; obtain equations to predict the maximum growth rate (μmax) of microbial communities as a function of temperature. The method consisted in conducting specific Substrate Activity Tests (SAT) using ISPAD inoculum to monitor the rate of degradation of specific substrates at 8, 18 and 35 °C. Microbial kinetics coefficients were obtained by fitting the Monod equations to SAT. The statistical procedure of Least Square Error analysis was used to minimize the Sum of Squared Errors (SSE) between the measured ISPAD experimental data and the Monod equation values. Comparing both fitting methods, the decomposition approach gave higher correlation coefficient (R) for most kinetics values, as compared to the conventional approach. Tested to predict μmax with temperature, the Square Root equation better predicted temperature dependency of both acidogens and propionate degrading acetogens, while the Arrhenius equation better predicted that of methanogens and butyrate degrading acetogens. Increasing temperature from 18 to 35 °C did not affect butyrate degrading acetogens, likely because of their dominance, as demonstrated by microbial population estimation. The estimated ISPAD kinetics coefficients suggest a robust psychrophilic and mesophilic coexisting microbial community demonstrating acclimation to ambient temperature. Copyright © 2014 Elsevier Ltd. All rights reserved.

Maximum in the Middle: Nonlinear Response of Microbial Plankton to Ultraviolet Radiation and Phosphorus

OpenAIRE

Medina-S?nchez, Juan Manuel; Delgado-Molina, Jos? Antonio; Bratbak, Gunnar; Bullejos, Francisco Jos?; Villar-Argaiz, Manuel; Carrillo, Presentaci?n

2013-01-01

The responses of heterotrophic microbial food webs (HMFW) to the joint action of abiotic stressors related to global change have been studied in an oligotrophic high-mountain lake. A 2??5 factorial design field experiment performed with large mesocosms for >2 months was used to quantify the dynamics of the entire HMFW (bacteria, heterotrophic nanoflagellates, ciliates, and viruses) after an experimental P-enrichment gradient which approximated or surpassed current atmospheric P pulses in the ...

Comparison of Microbial Communities in Swine Manure at Various Temperatures and storage times.

Science.gov (United States)

Lim, Joung-Soo; Yang, Seung Hak; Kim, Bong-Soo; Lee, Eun Young

2018-01-26

This study was designed to investigate the effects of temperature and storage time on the evolution of bacterial communities in swine manure. Manure was stored at -20°C, 4°C, 20°C, or 37°C and sampled at 7-day intervals over 28 days of storage, for a total of 5 time points. To assess the bacterial species present, 16S ribosomal RNA gene sequences were analyzed using pyrosequencing. After normalization, 113,934 sequence reads were obtained, with an average length of 466.6 ± 4.4 bp. The diversity indices of the communities reduced as temperature and storage time increased, and the slopes of rarefaction curves decreased from the second week in samples stored at -20 °C and 4 °C. These results indicate that the richness of the bacterial community in the manure reduced as temperature and storage time increased. Firmicutes were the dominant phylum in all samples examined, ranging from 89.3% to 98.8% of total reads, followed by Actinobacteria, which accounted for 0.6% to 7.9%. A change in community composition was observed in samples stored at 37 °C during the first 7 days, indicating that temperature plays an important role in determining the microbiota of swine manure. Clostridium, Turicibacter, Streptococcus, and Lactobacillus within Firmicutes, and Corynebacterium within Actinobacteria were the most dominant genera in fresh manure and all stored samples. Based on our findings, we propose Clostridium as an indicator genus of swine manure decomposition in an anaerobic environment. The proportions of dominant genera changed in samples stored at 20 °C and 37 °C during the fourth week. Based on these results, it was concluded that the microbial communities of swine manure change rapidly as storage time and temperature increase.

Olive Ridley Sea Turtle Hatching Success as a Function of Microbial Abundance and the Microenvironment of In Situ Nest Sand at Ostional, Costa Rica

Directory of Open Access Journals (Sweden)

Vanessa S. Bézy

2014-01-01

Full Text Available Sea turtle hatching success at mass nesting beaches is typically lower than at solitary nesting beaches, presumably due in part to high rates of microbial metabolism resulting from the large input of organic matter from turtle eggs. Therefore, we tested the hypothesis that hatching success varies across areas of the beach in conjunction with differences in the physical nest environment and microbial abundance of in situ olive ridley sea turtle nests at Ostional, Costa Rica. We marked natural nests in high-density, low-density, and tidal-wash nesting areas of the beach and monitored clutch pO2 and temperature throughout the incubation period. We quantified hatching success and collected samples of nest sand during nest excavations. We quantified microbial abundance (bacteria and fungi with a quantitative polymerase chain reaction (qPCR analysis. Hatching success was lower in nests with lower pO2, higher temperatures, higher organic matter content, and higher microbial abundance. Our results suggest that the lower oxygen within the nest environment is likely a result of the high microbial abundance and rates of decomposition in the nest sand and that these factors, along with increased temperature of clutches in the high-density nesting area, are collectively responsible for the low hatching success at Ostional.

Plant nutrient mobilization in temperate heathland responds to elevated CO2, temperature and drought

DEFF Research Database (Denmark)

Andresen, Louise C.; Michelsen, Anders; Jonasson, Sven

2010-01-01

Temperate terrestrial ecosystems are currently exposed to increased atmospheric CO2 and progressive climatic changes with increased temperature and periodical drought. We here present results from a field experiment, where the effects of these three main climate change related factors...... decreased in response to drought. These complex changes in availability and release of nutrients from soil organic matter turnover and mineralization in response to elevated CO2 and climate change may influence the future plant carbon sequestration and species composition at temperate heathlands....... in Deschampsia soil, and microbial immobilization of N and P decreased in warmed Calluna soil. Warming tended to increase microbial N and P in Calluna but not in Deschampsia soil in fall, and more microbial C was accumulated under drought in Calluna soil. The effects of warming were often counteracted or erased...

[Effects of variable temperature on organic carbon mineralization in typical limestone soils].

Science.gov (United States)

Wang, Lian-Ge; Gao, Yan-Hong; Ding, Chang-Huan; Ci, En; Xie, De-Ti

2014-11-01

Soil sampling in the field and incubation experiment in the laboratory were conducted to investigate the responses of soil organic carbon (SOC) mineralization to variable temperature regimes in the topsoil of limestone soils from forest land and dry land. Two incubated limestone soils were sampled from the 0-10 cm layers of typical forest land and dry land respectively, which were distributed in Tianlong Mountain area of Puding county, Guizhou province. The soils were incubated for 56 d under two different temperature regimes including variable temperature (range: 15-25 degrees C, interval: 12 h) and constant temperature (20 degrees C), and the cumulative temperature was the same in the two temperature treatments. In the entire incubation period (56 d), the SOC cumulative mineralization (63.32 mg x kg(-1)) in the limestone soil from dry land (SH) under the variable temperature was lower than that (63.96 mg x kg(-1)) at constant 20 degrees C, and there was no significant difference in the SOC cumulative mineralization between the variable and constant temperature treatments (P variable temperature was significantly lower than that (209.52 mg x kg(-1)) at constant 20 degrees C. The results indicated that the responses of SOC mineralization to the variable temperature were obviously different between SL and SH soils. The SOC content and composition were significantly different between SL and SH soils affected by vegetation and land use type, which suggested that SOC content and composition were important factors causing the different responses of SOC mineralization to variable temperature between SL and SH soils. In addition, the dissolved organic carbon (DOC) content of two limestone soils were highly (P variable temperature mainly influenced SOC mineralization by changing microbial community activity rather than by changing microbial quantity.

New microbial resource: microbial diversity, function and dynamics in Chinese liquor starter.

Science.gov (United States)

Huang, Yuhong; Yi, Zhuolin; Jin, Yanling; Zhao, Yonggui; He, Kaize; Liu, Dayu; Zhao, Dong; He, Hui; Luo, Huibo; Zhang, Wenxue; Fang, Yang; Zhao, Hai

2017-11-06

Traditional Chinese liquor (Baijiu) solid state fermentation technology has lasted for several thousand years. The microbial communities that enrich in liquor starter are important for fermentation. However, the microbial communities are still under-characterized. In this study, 454 pyrosequencing technology was applied to comprehensively analyze the microbial diversity, function and dynamics of two most-consumed liquor starters (Jiang- and Nong-flavor) during production. In total, 315 and 83 bacterial genera and 72 and 47 fungal genera were identified in Jiang- and Nong-flavor liquor starter, respectively. The relatively high diversity was observed when the temperature increased to 70 and 62 °C for Jiang- and Nong-flavor liquor starter, respectively. Some thermophilic fungi have already been isolated. Microbial communities that might contribute to ethanol fermentation, saccharification and flavor development were identified and shown to be core communities in correlation-based network analysis. The predictively functional profile of bacterial communities showed significant difference in energy, carbohydrate and amino acid metabolism and the degradation of aromatic compounds between the two kinds of liquor starters. Here we report these liquor starters as a new functionally microbial resource, which can be used for discovering thermophilic and aerobic enzymes and for food and feed preservation.

Oral temperature and cardiovascular responses of apparently ...

African Journals Online (AJOL)

Oral temperature and cardiovascular responses of apparently healthy subjects to passive and active warm-up. BOA Adegoke, OO Ogwumike, FA Maruf. Abstract. This study investigated and compared the effects of active and passive warm-up on oral temperature and cardiovascular parameters of forty (20 males and 20 ...

TLR-dependent human mucosal epithelial cell responses to microbial pathogens.

Directory of Open Access Journals (Sweden)

Paola eMassari

2014-08-01

Full Text Available AbstractToll-Like Receptor (TLR signaling represents one of the best studied pathways to implement defense mechanisms against invading microbes in humans as well as in animals. TLRs respond to specific microbial ligands and to danger signals produced by the host during infection, and initiate downstream cascades that activate both innate and adaptive immunity. TLRs are expressed by professional immune cells and by the large majority of non-hematopoietic cells, including epithelial cells. In epithelial tissues, TLR functions are particularly important because these sites are constantly exposed to microorganisms, due to their location at the host interface with the environment. While at these sites, specific defense mechanisms and inflammatory responses are initiated via TLR signaling against pathogens, suppression or lack of TLR activation is also observed in response to the commensal microbiota. The mechanisms by which TLR signaling is regulated in mucosal epithelial cells include differential expression and levels of TLRs (and their signaling partners, their cellular localization and positioning within the tissue in a fashion that favors responses to pathogens while dampening responses to commensals and maintaining tissue homeostasis in physiologic conditions. In this review, the expression and activation of TLRs in mucosal epithelial cells of several sites of the human body are examined. Specifically, the oral cavity, the ear canal and eye, the airways, the gut and the reproductive tract are discussed, along with how site-specific host defense mechanisms are implemented via TLR signaling.

Compositional differences in simulated root exudates elicit a limited functional and compositional response in soil microbial communities

Directory of Open Access Journals (Sweden)

Michael S Strickland

2015-08-01

Full Text Available Inputs of low molecular weight carbon (LMW-C to soil −primarily via root exudates− are expected to be a major driver of microbial activity and source of stable soil organic carbon. It is expected that variation in the type and composition of LMW-C entering soil will influence microbial community composition and function. If this is the case then short-term changes in LMW-C inputs may alter processes regulated by these communities. To determine if change in the composition of LMW-C inputs influences microbial community function and composition, we conducted a 90 day microcosm experiment whereby soils sourced from three different land covers (meadows, deciduous forests, and white pine stands were amended, at low concentrations, with one of eight simulated root exudate treatments. Treatments included no addition of LMW-C, and the full factorial combination of glucose, glycine, and oxalic acid. After 90 days, we conducted a functional response assay and determined microbial composition via phospholipid fatty acid analysis. Whereas we noted a statistically significant effect of exudate treatments, this only accounted for ~3% of the variation observed in function. In comparison, land cover and site explained ~46 and ~41% of the variation, respectively. This suggests that exudate composition has little influence on function

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

Science.gov (United States)

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

2015-12-01

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

Microbial UV fluence-response assessment using a novel UV-LED collimated beam system.

Science.gov (United States)

Bowker, Colleen; Sain, Amanda; Shatalov, Max; Ducoste, Joel

2011-02-01

A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms. Copyright © 2010 Elsevier Ltd. All rights reserved.

Microbial Threats to Health: Emergence, Detection, and Response

National Research Council Canada - National Science Library

Smolinski, Mark S; Hamburg, Margaret A; Lederberg, Joshua

2003-01-01

.... The recent SARS outbreak is a prime example. Knowing neither geographic nor political borders, often arriving silently and lethally, microbial pathogens constitute a grave threat to the health of humans...

Systems-level analysis of Escherichia coli response to silver nanoparticles: the roles of anaerobic respiration in microbial resistance.

Science.gov (United States)

Du, Huamao; Lo, Tat-Ming; Sitompul, Johnner; Chang, Matthew Wook

2012-08-10

Despite extensive use of silver nanoparticles for antimicrobial applications, cellular mechanisms underlying microbial response to silver nanoparticles remain to be further elucidated at the systems level. Here, we report systems-level response of Escherichia coli to silver nanoparticles using transcriptome-based biochemical and phenotype assays. Notably, we provided the evidence that anaerobic respiration is induced upon exposure to silver nanoparticles. Further we showed that anaerobic respiration-related regulators and enzymes play an important role in E. coli resistance to silver nanoparticles. In particular, our results suggest that arcA is essential for resistance against silver NPs and the deletion of fnr, fdnH and narH significantly increases the resistance. We envision that this study offers novel insights into modes of antimicrobial action of silver nanoparticles, and cellular mechanisms contributing to the development of microbial resistance to silver nanoparticles. Copyright © 2012 Elsevier Inc. All rights reserved.

Temperature response of permafrost soil carbon is attenuated by mineral protection.

Science.gov (United States)

Gentsch, Norman; Wild, Birgit; Mikutta, Robert; Čapek, Petr; Diáková, Katka; Schrumpf, Marion; Turner, Stephanie; Minnich, Cynthia; Schaarschmidt, Frank; Shibistova, Olga; Schnecker, Jörg; Urich, Tim; Gittel, Antje; Šantrůčková, Hana; Bárta, Jiři; Lashchinskiy, Nikolay; Fuß, Roland; Richter, Andreas; Guggenberger, Georg

2018-05-18

Climate change in Arctic ecosystems fosters permafrost thaw and makes massive amounts of ancient soil organic carbon (OC) available to microbial breakdown. However, fractions of the organic matter (OM) may be protected from rapid decomposition by their association with minerals. Little is known about the effects of mineral-organic associations (MOA) on the microbial accessibility of OM in permafrost soils and it is not clear which factors control its temperature sensitivity. In order to investigate if and how permafrost soil OC turnover is affected by mineral controls, the heavy fraction (HF) representing mostly MOA was obtained by density fractionation from 27 permafrost soil profiles of the Siberian Arctic. In parallel laboratory incubations, the unfractionated soils (bulk) and their HF were comparatively incubated for 175 days at 5 and 15°C. The HF was equivalent to 70 ± 9% of the bulk CO 2 respiration as compared to a share of 63 ± 1% of bulk OC that was stored in the HF. Significant reduction of OC mineralization was found in all treatments with increasing OC content of the HF (HF-OC), clay-size minerals and Fe or Al oxyhydroxides. Temperature sensitivity (Q10) decreased with increasing soil depth from 2.4 to 1.4 in the bulk soil and from 2.9 to 1.5 in the HF. A concurrent increase in the metal-to-HF-OC ratios with soil depth suggests a stronger bonding of OM to minerals in the subsoil. There, the younger 14 C signature in CO 2 than that of the OC indicates a preferential decomposition of the more recent OM and the existence of a MOA fraction with limited access of OM to decomposers. These results indicate strong mineral controls on the decomposability of OM after permafrost thaw and on its temperature sensitivity. Thus, we here provide evidence that OM temperature sensitivity can be attenuated by MOA in permafrost soils. © 2018 John Wiley & Sons Ltd.

Tropical Land Use Conversion Effects on Soil Microbial Community Structure and Function: Emerging Patterns and Knowledge Gaps

Science.gov (United States)

Seeley, M.; Marin-Spiotta, E.

2016-12-01

Modifications in vegetation due to land use conversions (LUC) between primary forests, pasture, cropping systems, tree plantations, and secondary forests drive shifts in soil microbial communities. These microbial community alterations affect carbon sequestration, nutrient cycling, aboveground biomass, and numerous other soil processes. Despite their importance, little is known about soil microbial organisms' response to LUC, especially in tropical regions where LUC rates are greatest. This project identifies current trends and uncertainties in tropical soil microbiology by comparing 56 published studies on LUC in tropical regions. This review indicates that microbial biomass and functional groups shifted in response to LUC, supporting demonstrated trends in changing soil carbon stocks due to LUC. Microbial biomass was greatest in primary forests when compared to secondary forests and in all forests when compared to both cropping systems and tree plantations. No trend existed when comparing pasture systems and forests, likely due to variations in pasture fertilizer use. Cropping system soils had greater gram positive and less gram negative bacteria than forest soils, potentially resulting in greater respiration of older carbon stocks in agricultural soils. Bacteria dominated primary forests while fungal populations were greatest in secondary forests. To characterize changes in microbial communities resulting from land use change, research must reflect the biophysical variation across the tropics. A chi-squared test revealed that the literature sites represented mean annual temperature variation across the tropics (p-value=0.66).

Temperature sensitivity of respiration scales with organic matter recalcitrance

Science.gov (United States)

Craine, J. M.; Fierer, N.; McLauchlan, K. K.

2010-12-01

Microbial decomposition of soil organic matter is a key process in determining the carbon sequestration potential of ecosystems and carbon fluxes to the atmosphere. Since microbial decomposition is highly sensitive to short-term changes in temperature, predicting the temperature sensitivity of microbial decomposition is critical to predicting future atmospheric carbon dioxide concentrations and feedbacks to anthropogenic warming. Fundamental principles of enzyme kinetics, embodied in the carbon-quality temperature hypothesis, predict that the temperature sensitivity of microbial decomposition should increase with increasing biochemical recalcitrance of a substrate. To test the generality of this principle, we measured the temperature sensitivity of microbial respiration of soil organic matter with serial short-term temperature manipulations over 365 days for 28 North American soils. When joined with data from similar studies that represent a wide variety of contrasts, we show that the temperature sensitivity of organic matter decomposition scales with biochemical recalcitrance. With physico-chemical protection likely an important covariate for relating plant and soil organic matter decomposition scalars, biochemically recalcitrant organic matter is highly susceptible to short-term increases in temperature, a key link in predicting the effects of warming on carbon cycling.

Temperature Response in Hardened Concrete Subjected to Tropical Rainforest Environment

Directory of Open Access Journals (Sweden)

E. I. Egba

2017-06-01

Full Text Available The objective of this paper is to characterize concrete micro-environment temperature response to the natural climate of the tropical rainforest. The peculiar warmth, high humidity, and low pressure nature of the tropical rainforest necessitated the present study. Temperature probes were inserted into concrete specimens subjected to the sheltered and unsheltered environment to measure the micro-environment temperature of the concrete, and study the hysteresis characteristics in relation to the climate temperature. Some mathematical relationships for forecasting the internal temperature of concrete in the tropical rainforest environment were proposed and tested. The proposed relationships were found reliable. It was observed that the micro-environment temperature was lower at the crest, and higher at the trough than the climate environment temperature with a temperature difference of 1-3 oC. Also, temperature response in concrete for the unsheltered micro-environment was 1.85 times faster than the response in the sheltered micro-environment. The findings of the study may be used to assist the durability assessment of concrete.

Soil microbial community response to aboveground vegetation and ...

African Journals Online (AJOL)

lenovo

2011-11-21

Nov 21, 2011 ... magnitude, activity, structure and function of soil microbial community may .... CaO were quantified by inductively coupled plasmaatomic emission spectroscopy ...... Validation of signature polarlipid fatty acid biomarkers for ...

Microbial endogenous response to acute inhibitory impact of antibiotics.

Science.gov (United States)

Pala-Ozkok, I; Kor-Bicakci, G; Çokgör, E U; Jonas, D; Orhon, D

2017-06-13

Enhanced endogenous respiration was observed as the significant/main response of the aerobic microbial culture under pulse exposure to antibiotics: sulfamethoxazole, tetracycline and erythromycin. Peptone mixture and acetate were selected as organic substrates to compare the effect of complex and simple substrates. Experiments were conducted with microbial cultures acclimated to different sludge ages of 10 and 2 days, to visualize the effect of culture history. Evaluation relied on modeling of oxygen uptake rate profiles, reflecting the effect of all biochemical reactions associated with substrate utilization. Model calibration exhibited significant increase in values of endogenous respiration rate coefficient with all antibiotic doses. Enhancement of endogenous respiration was different with antibiotic type and initial dose. Results showed that both peptone mixture and acetate cultures harbored resistance genes against the tested antibiotics, which suggests that biomass spends cellular maintenance energy for activating the required antibiotic resistance mechanisms to survive, supporting higher endogenous decay rates. [Formula: see text]: maximum growth rate for X H (day -1 ); K S : half saturation constant for growth of X H (mg COD/L); b H : endogenous decay rate for X H (day -1 ); k h : maximum hydrolysis rate for S H1 (day -1 ); K X : hydrolysis half saturation constant for S H1 (mg COD/L); k hx : maximum hydrolysis rate for X S1 (day -1 ); K XX : hydrolysis half saturation constant for X S1 (mg COD/L); k STO : maximum storage rate of PHA by X H (day -1 ); [Formula: see text]: maximum growth rate on PHA for X H (day -1 ); K STO : half saturation constant for storage of PHA by X H (mg COD/L); X H1 : initial active biomass (mg COD/L).

Soil microbial community structure is unaltered by plant invasion, vegetation clipping, and nitrogen fertilization in experimental semi-arid grasslands

Directory of Open Access Journals (Sweden)

Chelsea J Carey

2015-05-01

Full Text Available Global and regional environmental changes often co-occur, creating complex gradients of disturbance on the landscape. Soil microbial communities are an important component of ecosystem response to environmental change, yet little is known about how microbial structure and function respond to multiple disturbances, or whether multiple environmental changes lead to unanticipated interactive effects. Our study used experimental semi-arid grassland plots in a Mediterranean-climate to determine how soil microbial communities in a seasonally variable ecosystem respond to one, two, or three simultaneous environmental changes: exotic plant invasion, plant invasion + vegetation clipping (to simulate common management practices like mowing or livestock grazing, plant invasion + nitrogen (N fertilization, and plant invasion + clipping + N fertilization. We examined microbial community structure 5-6 years after plot establishment via sequencing of >1 million 16S rRNA genes. Abiotic soil properties (soil moisture, temperature, pH, and inorganic N and microbial functioning (nitrification and denitrification potentials were also measured and showed treatment-induced shifts, including altered NO3- availability, temperature, and nitrification potential. Despite these changes, bacterial and archaeal communities showed little variation in composition and diversity across treatments. Even communities in plots exposed to three interacting environmental changes were similar to those in restored native grassland plots. Historical exposure to large seasonal and inter-annual variations in key soil properties, in addition to prior site cultivation, may select for a functionally plastic or largely dormant microbial community, resulting in a microbial community that is structurally robust to single and multiple environmental changes.

Eye surface temperature detects stress response in budgerigars (Melopsittacus undulatus).

Science.gov (United States)

Ikkatai, Yuko; Watanabe, Shigeru

2015-08-05

Previous studies have suggested that stressors not only increase body core temperature but also body surface temperature in many animals. However, it remains unclear whether surface temperature could be used as an alternative to directly measure body core temperature, particularly in birds. We investigated whether surface temperature is perceived as a stress response in budgerigars. Budgerigars have been used as popular animal models to investigate various neural mechanisms such as visual perception, vocal learning, and imitation. Developing a new technique to understand the basic physiological mechanism would help neuroscience researchers. First, we found that cloacal temperature correlated with eye surface temperature. Second, eye surface temperature increased after handling stress. Our findings suggest that eye surface temperature is closely related to cloacal temperature and that the stress response can be measured by eye surface temperature in budgerigars.

Phospholipids fatty acids of drinking water reservoir sedimentary microbial community: Structure and function responses to hydrostatic pressure and other physico-chemical properties.

Science.gov (United States)

Chai, Bei-Bei; Huang, Ting-Lin; Zhao, Xiao-Guang; Li, Ya-Jiao

2015-07-01

Microbial communities in three drinking water reservoirs, with different depth in Xi'an city, were quantified by phospholipids fatty acids analysis and multivariate statistical analysis was employed to interpret their response to different hydrostatic pressure and other physico-chemical properties of sediment and overlying water. Principle component analyses of sediment characteristics parameters showed that hydrostatic pressure was the most important effect factor to differentiate the overlying water quality from three drinking water reservoirs from each other. NH4+ content in overlying water was positive by related to hydrostatic pressure, while DO in water-sediment interface and sediment OC in sediment were negative by related with it. Three drinking water reservoir sediments were characterized by microbial communities dominated by common and facultative anaerobic Gram-positive bacteria, as well as, by sulfur oxidizing bacteria. Hydrostatic pressure and physico-chemical properties of sediments (such as sediment OC, sediment TN and sediment TP) were important effect factors to microbial community structure, especially hydrostatic pressure. It is also suggested that high hydrostatic pressure and low dissolved oxygen concentration stimulated Gram-positive and sulfate-reducing bacteria (SRB) bacterial population in drinking water reservoir sediment. This research supplied a successful application of phospholipids fatty acids and multivariate analysis to investigate microbial community composition response to different environmental factors. Thus, few physico-chemical factors can be used to estimate composition microbial of community as reflected by phospholipids fatty acids, which is difficult to detect.

Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes

Science.gov (United States)

Portner, H.; Wolf, A.; Bugmann, H.

2009-04-01

Many biogeochemical models have been applied to study the response of the carbon cycle to changes in climate, whereby the process of carbon uptake (photosynthesis) has usually gained more attention than the equally important process of carbon release by respiration. The decomposition of soil organic matter is driven by a combination of factors with a prominent one being soil temperature [Berg and Laskowski(2005)]. One uncertainty concerns the response function used to describe the sensitivity of soil organic matter decomposition to temperature. This relationship is often described by one out of a set of similar exponential functions, but it has not been investigated how uncertainties in the choice of the response function influence the long term predictions of biogeochemical models. We built upon the well-established LPJ-GUESS model [Smith et al.(2001)]. We tested five candidate functions and calibrated them against eight datasets from different Ameriflux and CarboEuropeIP sites [Hibbard et al.(2006)]. We used a simple Exponential function with a constant Q10, the Arrhenius function, the Gaussian function [Tuomi et al.(2008), O'Connell(1990)], the Van't Hoff function [Van't Hoff(1901)] and the Lloyd&Taylor function [Lloyd and Taylor(1994)]. We assessed the impact of uncertainty in model formulation of temperature response on estimates of present and future long-term carbon storage in ecosystems and hence on the CO2 feedback potential to the atmosphere. We specifically investigated the relative importance of model formulation and the error introduced by using different data sets for the parameterization. Our results suggested that the Exponential and Arrhenius functions are inappropriate, as they overestimated the respiration rates at lower temperatures. The Gaussian, Van't Hoff and Lloyd&Taylor functions all fit the observed data better, whereby the functions of Gaussian and Van't Hoff underestimated the response at higher temperatures. We suggest, that the

Coping with temperature at the warm edge--patterns of thermal adaptation in the microbial eukaryote Paramecium caudatum.

Directory of Open Access Journals (Sweden)

Sascha Krenek

Full Text Available Ectothermic organisms are thought to be severely affected by global warming since their physiological performance is directly dependent on temperature. Latitudinal and temporal variations in mean temperatures force ectotherms to adapt to these complex environmental conditions. Studies investigating current patterns of thermal adaptation among populations of different latitudes allow a prediction of the potential impact of prospective increases in environmental temperatures on their fitness.In this study, temperature reaction norms were ascertained among 18 genetically defined, natural clones of the microbial eukaryote Paramecium caudatum. These different clones have been isolated from 12 freshwater habitats along a latitudinal transect in Europe and from 3 tropical habitats (Indonesia. The sensitivity to increasing temperatures was estimated through the analysis of clone specific thermal tolerances and by relating those to current and predicted temperature data of their natural habitats. All investigated European clones seem to be thermal generalists with a broad thermal tolerance and similar optimum temperatures. The weak or missing co-variation of thermal tolerance with latitude does not imply local adaptation to thermal gradients; it rather suggests adaptive phenotypic plasticity among the whole European subpopulation. The tested Indonesian clones appear to be locally adapted to the less variable, tropical temperature regime and show higher tolerance limits, but lower tolerance breadths.Due to the lack of local temperature adaptation within the European subpopulation, P. caudatum genotypes at the most southern edge of their geographic range seem to suffer from the predicted increase in magnitude and frequency of summer heat waves caused by climate change.

Biodiversity of the microbial mat of the Garga hot spring.

Science.gov (United States)

Rozanov, Alexey Sergeevich; Bryanskaya, Alla Victorovna; Ivanisenko, Timofey Vladimirovich; Malup, Tatyana Konstantinovna; Peltek, Sergey Evgenievich

2017-12-28

Microbial mats are a good model system for ecological and evolutionary analysis of microbial communities. There are more than 20 alkaline hot springs on the banks of the Barguzin river inflows. Water temperature reaches 75 °C and pH is usually 8.0-9.0. The formation of microbial mats is observed in all hot springs. Microbial communities of hot springs of the Baikal rift zone are poorly studied. Garga is the biggest hot spring in this area. In this study, we investigated bacterial and archaeal diversity of the Garga hot spring (Baikal rift zone, Russia) using 16S rRNA metagenomic sequencing. We studied two types of microbial communities: (i) small white biofilms on rocks in the points with the highest temperature (75 °C) and (ii) continuous thick phototrophic microbial mats observed at temperatures below 70 °C. Archaea (mainly Crenarchaeota; 19.8% of the total sequences) were detected only in the small biofilms. The high abundance of Archaea in the sample from hot springs of the Baikal rift zone supplemented our knowledge of the distribution of Archaea. Most archaeal sequences had low similarity to known Archaea. In the microbial mats, primary products were formed by cyanobacteria of the genus Leptolyngbya. Heterotrophic microorganisms were mostly represented by Actinobacteria and Proteobacteria in all studied samples of the microbial mats. Planctomycetes, Chloroflexi, and Chlorobi were abundant in the middle layer of the microbial mats, while heterotrophic microorganisms represented mostly by Firmicutes (Clostridia, strict anaerobes) dominated in the bottom part. Besides prokaryotes, we detect some species of Algae with help of detection their chloroplasts 16 s rRNA. High abundance of Archaea in samples from hot springs of the Baikal rift zone supplemented our knowledge of the distribution of Archaea. Most archaeal sequences had low similarity to known Archaea. Metagenomic analysis of microbial communities of the microbial mat of Garga hot spring showed that

Response of African marigold (Tagetes erecta L. to different concentrations of chlorpyrifos and microbial diversity in root rhizosphere

Directory of Open Access Journals (Sweden)

Mani Santhoshkumar

2017-04-01

Full Text Available Objective: To assess the response of African marigold (Tagetes erecta L. to exposed different concentration of chlorpyrifos by evaluating morphology (root and shoot length, biomass (fresh weight and dry weight, photosynthetic pigments (chlorophyll a and b, protein and microbial diversity in root rhizosphere. Methods: The study was carried out in pot culture and treated with various concentrations (0.5%, 1.0%, 2.0%, and 2.5% as well as control treatments. The morphological, biomass, photosynthetic pigments, protein, and microbial diversity were analyzed on 30, 60, and 90 days. Results: The obtained results revealed that the tested pesticide reduced the growth, biomass and photosynthetic pigment of African marigold when applied at higher concentration than the optimum dosage. But the lower dose the pesticide had some stimulatory effect of analyzed parameters. A similar effect of pesticide was observed on the microbial population of root rhizosphere that is decreased in microbial population was caused at higher doses. But it was increased at lower doses. Conclusions: It can be concluded that pesticide above the certain dosage level adversely affect all the analyzed parameters at higher doses. The application of recommended doses should be discouraged. Further study is needed for the effect of pesticide use on microbial diversity, since these studies are carried out in a controlled pot experiment, including the current study. Thus, future study directed towards by studying the phyoremediation of theses contaminted site with intraction of microbes.

Unfolding Role of a Danger Molecule Adenosine Signaling in Modulation of Microbial Infection and Host Cell Response

Directory of Open Access Journals (Sweden)

Jaden S. Lee

2018-01-01

Full Text Available Ectonucleotidases CD39 and CD73, specific nucleotide metabolizing enzymes located on the surface of the host, can convert a pro-inflammatory environment driven by a danger molecule extracellular-ATP to an adenosine-mediated anti-inflammatory milieu. Accordingly, CD39/CD73 signaling has been strongly implicated in modulating the intensity, duration, and composition of purinergic danger signals delivered to host. Recent studies have eluted potential roles for CD39 and CD73 in selective triggering of a variety of host immune cells and molecules in the presence of pathogenic microorganisms or microbial virulence molecules. Growing evidence also suggests that CD39 and CD73 present complimentary, but likely differential, actions against pathogens to shape the course and severity of microbial infection as well as the associated immune response. Similarly, adenosine receptors A2A and A2B have been proposed to be major immunomodulators of adenosine signaling during chronic inflammatory conditions induced by opportunistic pathogens, such as oral colonizer Porphyromonas gingivalis. Therefore, we here review the recent studies that demonstrate how complex network of molecules in the extracellular adenosine signaling machinery and their interactions can reshape immune responses and may also be targeted by opportunistic pathogens to establish successful colonization in human mucosal tissues and modulate the host immune response.

Behavioral Responses of Concholepas concholepas (Bruguière, 1789) Larvae to Natural and Artificial Settlement Cues and Microbial Films.

Science.gov (United States)

Rodriguez, S R; Riquelme, C; Campos, E O; Chavez, P; Brandan, E; Inestrosa, N C

1995-12-01

The behavioral responses of veliger larvae of the gastropod Concholepas concholepas were studied in the presence of different natural and artificial settlement cues and microbial films. Early pre-competent larvae stopped swimming, sank (due to ciliary arrests, retraction of the velum into the shell, or both), and remained inactive on the substratum when exposed to conspecific mucus and hemolymph. In both cases the effect was time-dependent and the number of larvae showing these behaviors decreased over time. Larvae exposed to NH4Cl (ammonium ion) showed a similar time- and dose-dependent response. A positive and time-dependent response was also observed when larvae were exposed to different extracellular matrix (ECM) components (i.e., collagen, gelatin, and fibronectin) and sulfated polysaccharides (i.e., carrageenan, heparin, and chondroitin sulfate). In this case the larvae remained attached to the substratum. However, the effect of sulfated polysaccharides on C. concholepas larval behavior was faster than that observed with other ECM molecules. We also studied the responses of premetamorphic C. concholepas larvae exposed to different microbial films. In chemotaxis experiments with different films, with glass as the substratum, larvae showed a significant preference for multispecific and diatoms films. When shells of C. concholepas were used as the substratum, the preference for multispecific films was clear and significant. Likewise, larvae showed velar contractions in the presence of all the films tested. Larvae exposed to multispecific films and to the microalga Prasinocladus marinus showed an increased ciliar movement. The finding that mucus and hemolymph of conspecific adults and ECM molecules (mainly sulfated polysaccharides) induce the cessation of swimming of C. concholepas larvae suggests a possible role for cell-surface receptors in mediating the larval response of marine organisms. Likewise, the positive chemotaxis responses of C. concholepas larvae to

Effects of phosphorus and nitrogen additions on tropical soil microbial activity in the context of experimental warming

Science.gov (United States)

Foley, M.; Nottingham, A.; Turner, B. L.

2017-12-01

Soil warming is generally predicted to increase microbial mineralization rates and accelerate soil C losses which could establish a positive feedback to climatic warming. Tropical rain forests account for a third of global soil C, yet the responseto of tropical soil C a warming climate remains poorly understood. Despite predictions of soil C losses, decomposition of soil organic matter (SOM) in tropical soils may be constrained by several factors including microbial nutrient deficiencies. We performed an incubation experiment in conjunction with an in-situ soil warming experiment in a lowland tropical forest on Barro Colorado Island, Panama, to measure microbial response to two key nutrient additions in shallow (0-10cm) and deep (50-100 cm) soils. We compared the response of lowland tropical soils to montane tropical soils, predicting that lowland soils would display the strongest response to phosphorus additions. Soils were treated with either carbon alone (C), nitrogen (CN), phosphorus (CP) or nitrogen and phosphorus combined (CNP). Carbon dioxide (CO2) production was measured by NaOH capture and titrimetric analysis for 10 days. Cumulative CO2 production in montane soils increased significantly with all additions, suggesting these soils are characterized by a general microbial nutrient deficiency. The cumulative amount of C respired in deep soils from the lowland site increased significantly with CP and CNP additions, suggesting that microbial processes in deep lowland tropical soils are phosphorus-limited. These results support the current understanding that lowland tropical forests are growing on highly weathered, phosphorus-deplete soils, and provide novel insight that deep tropical SOM may be stabilized by a lack of biologically-available phosphorus. Further, this data suggests tropical soil C losses under elevated temperature may be limited by a strong microbial phosphorus deficiency.

Soil microbial communities buffer physiological responses to drought stress in three hardwood species.

Science.gov (United States)

Kannenberg, Steven A; Phillips, Richard P

2017-03-01

Trees possess myriad adaptations for coping with drought stress, but the extent to which their drought responses are influenced by interactions with soil microbes is poorly understood. To explore the role of microbes in mediating tree responses to drought stress, we exposed saplings of three species (Acer saccharum, Liriodendron tulipifera, and Quercus alba) to a four week experimental drought in mesocosms. Half of the pots were inoculated with a live soil slurry (i.e., a microbial inoculum derived from soils beneath the canopies of mature A. saccharum, L. tulipifera or Q. alba stands), while the other half of the pots received a sterile soil slurry. Soil microbes ameliorated drought stress in L. tulipifera by minimizing reductions in leaf water potential and by reducing photosynthetic declines. In A. saccharum, soil microbes reduced drought stress by lessening declines in leaf water potential, though these changes did not buffer the trees from declining photosynthetic rates. In Q. alba, soil microbes had no effects on leaf physiological parameters during drought stress. In all species, microbes had no significant effects on dynamic C allocation during drought stress, suggesting that microbial effects on plant physiology were unrelated to source-sink dynamics. Collectively, our results suggest that soil microbes have the potential to alter key parameters that are used to diagnose drought sensitivity (i.e., isohydry or anisohydry). To the extent that our results reflect dynamics occurring in forests, a revised perspective on plant hydraulic strategies that considers root-microbe interactions may lead to improved predictions of forest vulnerability to drought.

Temperature transient response measurement in flowing water

International Nuclear Information System (INIS)

Rainbird, J.C.

1980-01-01

A specially developed procedure is described for determining the thermal transient response of thermocouples and other temperature transducers when totally immersed in flowing water. The high velocity heat transfer conditions associated with this facility enable thermocouple response times to be predicted in other fluids. These predictions can be confirmed by electrical analogue experiments. (author)

Carbon turnover in topsoil and subsoil: The microbial response to root litter additions and different environmental conditions in a reciprocal soil translocation experiment

Science.gov (United States)

Preusser, Sebastian; Poll, Christian; Marhan, Sven; Kandeler, Ellen

2017-04-01

At the global scale, soil organic carbon (SOC) represents the largest active terrestrial organic carbon (OC) pool. Carbon dynamics in subsoil, however, vary from those in topsoil with much lower C concentrations in subsoil than in topsoil horizons, although more than 50 % of SOC is stored in subsoils below 30 cm soil depth. In addition, microorganisms in subsoil are less abundant, more heterogeneously distributed and the microbial communities have a lower diversity than those in topsoil. Especially in deeper soil, the impact of changes in habitat conditions on microorganisms involved in carbon cycling are largely unexplored and consequently the understanding of microbial functioning is limited. A reciprocal translocation experiment allowed us to investigate the complex interaction effects of altered environmental and substrate conditions on microbial decomposer communities in both topsoil and subsoil habitats under in situ conditions. We conducted this experiment with topsoil (5 cm soil depth) and subsoil (110 cm) samples of an acid and sandy Dystric Cambisol from a European beech (Fagus sylvatica L.) forest in Lower Saxony, Germany. In total 144 samples were buried into three depths (5 cm, 45 cm and 110 cm) and 13C-labelled root litter was added to expose the samples to different environmental conditions and to increase the substrate availability, respectively. Samples were taken in three month intervals up to a maximum exposure time of one year to follow the temporal development over the experimental period. Analyses included 13Cmic and 13C PLFA measurements to investigate the response of microbial abundance, community structure and 13C-root decomposition activity under the different treatments. Environmental conditions in the respective soil depths such as soil temperature and water content were recorded throughout the experimental period. All microbial groups (gram+ and gram- bacteria, fungi) showed highest relative 13C incorporation in 110 cm depth and samples

Invasion in microbial communities: Role of community composition and assembly processes

DEFF Research Database (Denmark)

Kinnunen, Marta

of microbial community assembly. Biotic factors include interactions between different microbial groups as well as the community response to alien species – invaders. Microbial invasions can have significant effects on the composition and functioning of resident communities. There is, however, lack......Microbes contribute to all biogeochemical cycles on earth and are responsible for key biological processes that support the survival of plants and animals. There is increased interest in controlling and managing microbial communities in different ecosystems in order to make targeted microbiological...... processes more effective. In order to manage microbial communities, it is essential to understand the factors that shape and influence microbial community composition. In addition to abiotic factors, such as environmental conditions and resource availability, biotic factors also shape the dynamics...

Response of aerobic granular sludge to the long-term presence to nanosilver in sequencing batch reactors: Reactor performance, sludge property, microbial activity and community

Energy Technology Data Exchange (ETDEWEB)

Quan, Xiangchun, E-mail: xchquan@bnu.edu.cn; Cen, Yan; Lu, Fang; Gu, Lingyun; Ma, Jingyun

2015-02-15

The increasing use of silver nanoparticles (Ag NPs) raises concerns about their potential toxic effects on the environment. Granular shape sludge is a special type of microbial aggregate. The response of aerobic granular sludge (AGS) to the long-term presence of Ag NPs has not been well studied. In this study, AGS was exposed to 5 and 50 mg/L Ag NPs in sequence batch reactors (SBRs) for 69 days, and its response was evaluated based on the sludge properties, microbial activity and community, and reactor performance. The results showed that Ag NPs caused inhibition to microbial activities of AGS from Day 35. At the end of 69 days of Ag NPs exposure, the microbial activity of AGS was significantly inhibited in terms of inhibitions of the ammonia oxidizing rate (33.0%), respiration rate (17.7% and 45.6%) and denitrification rate (6.8%), as well as decreases in the ammonia mono-oxygenase and nitrate reductase activities. During the long-term exposure, the AGS maintained its granular shape and large granule size (approximately 900 μm); the microbial community of AGS slightly changed, but the dominant microbial population remained. Overall, the AGS tolerated the toxicity of Ag NPs well, but a long-term exposure may produce chronic toxicity to the AGS, which is concerning. - Highlights: • AGS demonstrated a good tolerance to the long-term presence of Ag NPs. • Ag NPs did not produce acute toxicity but cause chronic toxicity to AGS. • AGS maintained granular shape, granule size and good settling ability. • The microbial community of AGS slightly changed after long-term Ag NPs exposure.

Response of aerobic granular sludge to the long-term presence to nanosilver in sequencing batch reactors: Reactor performance, sludge property, microbial activity and community

International Nuclear Information System (INIS)

Quan, Xiangchun; Cen, Yan; Lu, Fang; Gu, Lingyun; Ma, Jingyun

2015-01-01

The increasing use of silver nanoparticles (Ag NPs) raises concerns about their potential toxic effects on the environment. Granular shape sludge is a special type of microbial aggregate. The response of aerobic granular sludge (AGS) to the long-term presence of Ag NPs has not been well studied. In this study, AGS was exposed to 5 and 50 mg/L Ag NPs in sequence batch reactors (SBRs) for 69 days, and its response was evaluated based on the sludge properties, microbial activity and community, and reactor performance. The results showed that Ag NPs caused inhibition to microbial activities of AGS from Day 35. At the end of 69 days of Ag NPs exposure, the microbial activity of AGS was significantly inhibited in terms of inhibitions of the ammonia oxidizing rate (33.0%), respiration rate (17.7% and 45.6%) and denitrification rate (6.8%), as well as decreases in the ammonia mono-oxygenase and nitrate reductase activities. During the long-term exposure, the AGS maintained its granular shape and large granule size (approximately 900 μm); the microbial community of AGS slightly changed, but the dominant microbial population remained. Overall, the AGS tolerated the toxicity of Ag NPs well, but a long-term exposure may produce chronic toxicity to the AGS, which is concerning. - Highlights: • AGS demonstrated a good tolerance to the long-term presence of Ag NPs. • Ag NPs did not produce acute toxicity but cause chronic toxicity to AGS. • AGS maintained granular shape, granule size and good settling ability. • The microbial community of AGS slightly changed after long-term Ag NPs exposure

Microorganism-regulated mechanisms of temperature effects on the performance of anaerobic digestion.

Science.gov (United States)

Lin, Qiang; He, Guihua; Rui, Junpeng; Fang, Xiaoyu; Tao, Yong; Li, Jiabao; Li, Xiangzhen

2016-06-03

Temperature is an important factor determining the performance and stability of the anaerobic digestion process. However, the microorganism-regulated mechanisms of temperature effects on the performance of anaerobic digestion systems remain further elusive. To address this issue, we investigated the changes in composition, diversity and activities of microbial communities under temperature gradient from 25 to 55 °C using 16S rRNA gene amplicon sequencing approach based on genomic DNA (refer to as "16S rDNA") and total RNA (refer to as "16S rRNA"). Microbial community structure and activities changed dramatically along the temperature gradient, which corresponded to the variations in digestion performance (e.g., daily CH4 production, total biogas production and volatile fatty acids concentration). The ratios of 16S rRNA to 16S rDNA of microbial taxa, as an indicator of the potentially relative activities in situ, and whole activities of microbial community assessed by the similarity between microbial community based on 16S rDNA and rRNA, varied strongly along the temperature gradient, reflecting different metabolic activities. The daily CH4 production increased with temperature from 25 to 50 °C and declined at 55 °C. Among all the examined microbial properties, the whole activities of microbial community and alpha-diversity indices of both microbial communities and potentially relative activities showed highest correlations to the performance. The whole activities of microbial community and alpha-diversity indices of both microbial communities and potentially relative activities were sensitive indicators for the performance of anaerobic digestion systems under temperature gradient, while beta-diversity could predict functional differences. Microorganism-regulated mechanisms of temperature effects on anaerobic digestion performance were likely realized through increasing alpha-diversity of both microbial communities and potentially relative activities to supply

Muscles provide protection during microbial infection by activating innate immune response pathways in Drosophila and zebrafish

Directory of Open Access Journals (Sweden)

Arunita Chatterjee

2016-06-01

Full Text Available Muscle contraction brings about movement and locomotion in animals. However, muscles have also been implicated in several atypical physiological processes including immune response. The role of muscles in immunity and the mechanism involved has not yet been deciphered. In this paper, using Drosophila indirect flight muscles (IFMs as a model, we show that muscles are immune-responsive tissues. Flies with defective IFMs are incapable of mounting a potent humoral immune response. Upon immune challenge, the IFMs produce anti-microbial peptides (AMPs through the activation of canonical signaling pathways, and these IFM-synthesized AMPs are essential for survival upon infection. The trunk muscles of zebrafish, a vertebrate model system, also possess the capacity to mount an immune response against bacterial infections, thus establishing that immune responsiveness of muscles is evolutionarily conserved. Our results suggest that physiologically fit muscles might boost the innate immune response of an individual.

The underestimated role of temperature-oxygen relationship in large-scale studies on size-to-temperature response.

Science.gov (United States)

Walczyńska, Aleksandra; Sobczyk, Łukasz

2017-09-01

The observation that ectotherm size decreases with increasing temperature (temperature-size rule; TSR) has been widely supported. This phenomenon intrigues researchers because neither its adaptive role nor the conditions under which it is realized are well defined. In light of recent theoretical and empirical studies, oxygen availability is an important candidate for understanding the adaptive role behind TSR. However, this hypothesis is still undervalued in TSR studies at the geographical level. We reanalyzed previously published data about the TSR pattern in diatoms sampled from Icelandic geothermal streams, which concluded that diatoms were an exception to the TSR. Our goal was to incorporate oxygen as a factor in the analysis and to examine whether this approach would change the results. Specifically, we expected that the strength of size response to cold temperatures would be different than the strength of response to hot temperatures, where the oxygen limitation is strongest. By conducting a regression analysis for size response at the community level, we found that diatoms from cold, well-oxygenated streams showed no size-to-temperature response, those from intermediate temperature and oxygen conditions showed reverse TSR, and diatoms from warm, poorly oxygenated streams showed significant TSR. We also distinguished the roles of oxygen and nutrition in TSR. Oxygen is a driving factor, while nutrition is an important factor that should be controlled for. Our results show that if the geographical or global patterns of TSR are to be understood, oxygen should be included in the studies. This argument is important especially for predicting the size response of ectotherms facing climate warming.

Microbial electrode sensor for alcohols

Energy Technology Data Exchange (ETDEWEB)

Hikuma, M [Ajinomoto Co., Inc., Kawasaki, Japan; Kubo, T; Yasuda, T; Karube, I; Suzuki, S

1979-10-01

A microbial electrode consisting of immobilized microorganisms, a gas permeable Teflon membrane, and an oxygen electrode was prepared for the continuous determination of methyl and ethyl alcohols. Immobilized Trichosporon brassicae was employed for a microbial electrode sensor for ethyl alcohol. When a sample solution containing ethyl alcohol was injected into a microbial electrode system, the current of the electrode decreased markedly with time until a steady state was reached. The response time was within 10 min by the steady state method and within 6 min by the pulse method. A linear relationship was observed between the current decrease and the concentration of ethyl alcohol below 22.5 mg/liter. The current was reproducible within +- 6% of the relative error when a sample solution containing 16.5 mg/liter ethyl alcohol. The standard deviation was 0.5 mg/liter in 40 experiments. The selectivity of the microbial electrode sensor for ethyl alcohol was satisfactory. The microbial electrode sensor was applied to a fermentation broth of yeasts and satisfactory comparative results were obtained (correlation coefficient 0.98). The current output of the microbial electrode sensor was almost constant for more than three weeks and 2100 assays. A microbial electrode sensor using immobilized bacteria for methyl alcohol was also described.

Metal oxides, clay minerals and charcoal determine the composition of microbial communities in matured artificial soils and their response to phenanthrene.

Science.gov (United States)

Babin, Doreen; Ding, Guo-Chun; Pronk, Geertje Johanna; Heister, Katja; Kögel-Knabner, Ingrid; Smalla, Kornelia

2013-10-01

Microbial communities in soil reside in a highly heterogeneous habitat where diverse mineral surfaces, complex organic matter and microorganisms interact with each other. This study aimed to elucidate the long-term effect of the soil mineral composition and charcoal on the microbial community composition established in matured artificial soils and their response to phenanthrene. One year after adding sterile manure to different artificial soils and inoculating microorganisms from a Cambisol, the matured soils were spiked with phenanthrene or not and incubated for another 70 days. 16S rRNA gene and internal transcribed spacer fragments amplified from total community DNA were analyzed by denaturing gradient gel electrophoresis. Metal oxides and clay minerals and to a lesser extent charcoal influenced the microbial community composition. Changes in the bacterial community composition in response to phenanthrene differed depending on the mineral composition and presence of charcoal, while no shifts in the fungal community composition were observed. The abundance of ring-hydroxylating dioxygenase genes was increased in phenanthrene-spiked soils except for charcoal-containing soils. Here we show that the formation of biogeochemical interfaces in soil is an ongoing process and that different properties present in artificial soils influenced the bacterial response to the phenanthrene spike. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Tropical forest carbon balance in a warmer world: a critical review spanning microbial- to ecosystem-scale processes

Science.gov (United States)

Wood, Tana E.; Cavaleri, Molly A.; Reed, Sasha C.

2012-01-01

Tropical forests play a major role in regulating global carbon (C) fluxes and stocks, and even small changes to C cycling in this productive biome could dramatically affect atmospheric carbon dioxide (CO2) concentrations. Temperature is expected to increase over all land surfaces in the future, yet we have a surprisingly poor understanding of how tropical forests will respond to this significant climatic change. Here we present a contemporary synthesis of the existing data and what they suggest about how tropical forests will respond to increasing temperatures. Our goals were to: (i) determine whether there is enough evidence to support the conclusion that increased temperature will affect tropical forest C balance; (ii) if there is sufficient evidence, determine what direction this effect will take; and, (iii) establish what steps should to be taken to resolve the uncertainties surrounding tropical forest responses to increasing temperatures. We approach these questions from a mass-balance perspective and therefore focus primarily on the effects of temperature on inputs and outputs of C, spanning microbial- to ecosystem-scale responses. We found that, while there is the strong potential for temperature to affect processes related to C cycling and storage in tropical forests, a notable lack of data combined with the physical, biological and chemical diversity of the forests themselves make it difficult to resolve this issue with certainty. We suggest a variety of experimental approaches that could help elucidate how tropical forests will respond to warming, including large-scale in situ manipulation experiments, longer term field experiments, the incorporation of a range of scales in the investigation of warming effects (both spatial and temporal), as well as the inclusion of a diversity of tropical forest sites. Finally, we highlight areas of tropical forest research where notably few data are available, including temperature effects on: nutrient cycling

Microbial communities of the deep unfrozen: Do microbes in taliks increase permafrost carbon vulnerability? (Invited)

Science.gov (United States)

Waldrop, M. P.; Blazewicz, S.; Jones, M.; Mcfarland, J. W.; Harden, J. W.; Euskirchen, E. S.; Turetsky, M.; Hultman, J.; Jansson, J.

2013-12-01

soils. To test this idea, we conducted anaerobic incubations of deep (1m) bog soils at two different temperatures to determine microbial temperature response functions. We also measured soil profile CO2 and CH4 concentrations and functional gene assays of the deep bog microbial community. Incubation data in combination with overwinter temperature profiles show that the talik has high potential rates of CO2 and CH4 production compared to the mass of C from forest floor and permafrost C to 1m depth. Results highlight the potential importance of taliks affecting the vulnerability of permafrost carbon to decomposition and reduction to methane.

Microbial O2 consumption in the Aespoe tunnel

International Nuclear Information System (INIS)

Kotelnikova, S.; Pedersen, Karsten

1998-04-01

The report presents data on microbial O 2 reduction activities by microorganisms obtained with different techniques: Winkler method, gas chromatography, most probable numbering, enrichment technique, inhibitor analysis and radiotracer measurements. The samples were collected from boreholes and open funnel ponds at Aespoe in 1996-1998. The evaluation of the microbial activities in open ponds predicts the future microbial activities after the O 2 intrusion around the future repository. The metabolic potential of the microbial population inhabiting groundwater was evaluated on the basis of electron donors available and microbial 16S rRNA gene diversity. The contribution of different microbial groups to the O 2 reduction was elucidated using specific inhibitors selectively affecting different microbial groups. Our experiments show that microbial O 2 reduction occurs in deep groundwater. Carbon dioxide was produced concurrently with O 2 reduction confirming the biogenic nature of the reduction. The populations developed O 2 reduction rates and capacity depending on the initial concentration of dissolved O 2 reduction. Rates of O 2 reduction ranged from 0.32 to 4.5 μM/day. Depending on temperature and the type of groundwater the approximate time needed for consumption of 500 μM of dissolved O 2 ranged from 0.31 to 3.99 years. After approximately a 2 weeks period the microbial population in vitro was able to consume O 2 both at 30 deg C and 60 deg C. At 16 deg C no delay in O 2 consumption was observed. Our results demonstrated that methanotrophs survive in deep groundwater and that they were induced by O 2 . Some bacteria use Hg or CH 4 as electron donor instead of organic matter, which means that microbial O 2 reduction will occur also in deep groundwaters where the availability of organic carbon is limited. Specific CH 4 oxidation rates ranged between 3.00 and 220 nM CH 4 per litre per day. Comparison of the total O 2 reducing activities by gas chromatography and

Microbial drivers of spatial heterogeneity of nitrous oxide pulse dynamics following drought in an experimental tropical rainforest

Science.gov (United States)

Young, J. C.; Sengupta, A.; U'Ren, J.; Van Haren, J. L. M.; Meredith, L. K.

2017-12-01

Nitrous oxide (N2O) is a long-lived, potent greenhouse gas with increasing atmospheric concentrations. Soil microbes in agricultural and natural ecosystems are the dominant source of N2O, which involves complex interactions between N-cycling microbes, metabolisms, soil properties, and plants. Tropical rainforests are the largest natural source of N2O, however the microbial and environmental drivers are poorly understood as few studies have been performed in these environments. Thus, there is an urgent need for further research to fill in knowledge gaps regarding tropical N-cycling, and the response of soil microbial communities to changes in precipitation patterns, temperature, nitrogen deposition, and land use. To address this data gap, we performed a whole-forest drought in the tropical rainforest biome in Biosphere 2 (B2) and analyzed connections between soil microbes, forest heterogeneity, and N2O emissions. The B2 rainforest is the hottest tropical rainforest on Earth, and is an important model system for studying the response of tropical forests to warming with controlled experimentation. In this study, we measured microbial community abundance and diversity profiles (16S rRNA and ITS2 amplicon sequencing) along with their association with soil properties (e.g. pH, C, N) during the drought and rewetting at five locations (3 depths), including regions that have been previously characterized with high and low N2O drought pulse dynamics (van Haren et al., 2005). In this study, we present the spatial distribution of soil microbial communities within the rainforest at Biosphere 2 and their correlations with edaphic factors. In particular, we focus on microbial, soil, and plant factors that drive high and low N2O pulse zones. As in the past, we found that N2O emissions were highest in response to rewetting in a zone hypothesized to be rich in nutrients from a nearby sugar palm. We will characterize microbial indicator species and nitrogen cycling genes to better

Study Progress of Physiological Responses in High Temperature Environment

Science.gov (United States)

Li, K.; Zheng, G. Z.; Bu, W. T.; Wang, Y. J.; Lu, Y. Z.

2017-10-01

Certain workers are exposed to high temperatures for a long time. Heat stress will result in a series of physiological responses, and cause adverse effects on the health and safety of workers. This paper summarizes the physiological changes of cardiovascular system, core temperature, skin temperature, water-electrolyte metabolism, alimentary system, neuroendocrine system, reaction time and thermal fatigue in high temperature environments. It can provide a theoretical guidance for labor safety in high temperature environment.

Seasonality in ocean microbial communities.

Science.gov (United States)

Giovannoni, Stephen J; Vergin, Kevin L

2012-02-10

Ocean warming occurs every year in seasonal cycles that can help us to understand long-term responses of plankton to climate change. Rhythmic seasonal patterns of microbial community turnover are revealed when high-resolution measurements of microbial plankton diversity are applied to samples collected in lengthy time series. Seasonal cycles in microbial plankton are complex, but the expansion of fixed ocean stations monitoring long-term change and the development of automated instrumentation are providing the time-series data needed to understand how these cycles vary across broad geographical scales. By accumulating data and using predictive modeling, we gain insights into changes that will occur as the ocean surface continues to warm and as the extent and duration of ocean stratification increase. These developments will enable marine scientists to predict changes in geochemical cycles mediated by microbial communities and to gauge their broader impacts.

Microbial Decomposers Not Constrained by Climate History Along a Mediterranean Climate Gradient

Science.gov (United States)

Baker, N. R.; Khalili, B.; Martiny, J. B. H.; Allison, S. D.

2017-12-01

The return of organic carbon to the atmosphere through terrestrial decomposition is mediated through the breakdown of complex organic polymers by extracellular enzymes produced by microbial decomposer communities. Determining if and how these decomposer communities are constrained in their ability to degrade plant litter is necessary for predicting how carbon cycling will be affected by future climate change. To address this question, we deployed fine-pore nylon mesh "microbial cage" litterbags containing grassland litter with and without local inoculum across five sites in southern California, spanning a gradient of 10.3-22.8° C in mean annual temperature and 100-400+ mm mean annual precipitation. Litterbags were deployed in October 2014 and collected four times over the course of 14 months. Recovered litter was assayed for mass loss, litter chemistry, microbial biomass, extracellular enzymes (Vmax and Km­), and enzyme temperature sensitivities. We hypothesized that grassland litter would decompose most rapidly in the grassland site, and that access to local microbial communities would enhance litter decomposition rates and microbial activity in the other sites along the gradient. We determined that temperature and precipitation likely interact to limit microbial decomposition in the extreme sites along our gradient. Despite their unique climate history, grassland microbes were not restricted in their ability to decompose litter under different climate conditions. Although we observed a strong correlation between bacterial biomass and mass loss across the gradient, litter that was inoculated with local microbial communities lost less mass despite having greater bacterial biomass and potentially accumulating more microbial residues. Our results suggest that microbial community composition may not constrain C-cycling rates under climate change in our system. However, there may be community constraints on decomposition if climate change alters litter chemistry, a

Copper removal and microbial community analysis in single-chamber microbial fuel cell.

Science.gov (United States)

Wu, Yining; Zhao, Xin; Jin, Min; Li, Yan; Li, Shuai; Kong, Fanying; Nan, Jun; Wang, Aijie

2018-04-01

In this study, copper removal and electricity generation were investigated in a single-chamber microbial fuel cell (MFC). Result showed that copper was efficiently removed in the membrane-less MFC with removal efficiency of 98.3% at the tolerable Cu 2+ concentration of 12.5 mg L -1 , the corresponding open circuit voltage and maximum power density were 0.78 V and 10.2 W m -3 , respectively. The mechanism analysis demonstrated that microbial electrochemical reduction contributed to the copper removal with the products of Cu and Cu 2 O deposited at biocathode. Moreover, the microbial community analysis indicated that microbial communities changed with different copper concentrations. The dominant phyla were Proteobacteria and Bacteroidetes which could play key roles in electricity generation, while Actinobacteria and Acidobacteria were also observed which were responsible for Cu-resistant and copper removal. It will be of important guiding significance for the recovery of copper from low concentration wastewater through single-chamber MFC with simultaneous energy recovery. Copyright © 2018 Elsevier Ltd. All rights reserved.

PCR-DGGE fingerprints of microbial successional changes during ...

African Journals Online (AJOL)

PCR-DGGE fingerprints of microbial successional changes during fermentation of cereal-legume weaning foods. ... African Journal of Biotechnology ... Phenotypic identification and monitoring of the dynamics of naturally occurring microbial community responsible for the spontaneous fermentation of different cereal-legume ...

Microbial analysis of meatballs cooled with vacuum and conventional cooling.

Science.gov (United States)

Ozturk, Hande Mutlu; Ozturk, Harun Kemal; Koçar, Gunnur

2017-08-01

Vacuum cooling is a rapid evaporative cooling technique and can be used for pre-cooling of leafy vegetables, mushroom, bakery, fishery, sauces, cooked food, meat and particulate foods. The aim of this study was to apply the vacuum cooling and the conventional cooling techniques for the cooling of the meatball and to show the vacuum pressure effect on the cooling time, the temperature decrease and microbial growth rate. The results of the vacuum cooling and the conventional cooling (cooling in the refrigerator) were compared with each other for different temperatures. The study shows that the conventional cooling was much slower than the vacuum cooling. Moreover, the microbial growth rate of the vacuum cooling was extremely low compared with the conventional cooling. Thus, the lowest microbial growth occurred at 0.7 kPa and the highest microbial growth was observed at 1.5 kPa for the vacuum cooling. The mass loss ratio for the conventional cooling and vacuum cooling was about 5 and 9% respectively.

Systems biology of Microbial Communities

Energy Technology Data Exchange (ETDEWEB)

Navid, A; Ghim, C; Fenley, A; Yoon, S; Lee, S; Almaas, E

2008-04-11

Microbes exist naturally in a wide range of environments, spanning the extremes of high acidity and high temperature to soil and the ocean, in communities where their interactions are significant. We present a practical discussion of three different approaches for modeling microbial communities: rate equations, individual-based modeling, and population dynamics. We illustrate the approaches with detailed examples. Each approach is best fit to different levels of system representation, and they have different needs for detailed biological input. Thus, this set of approaches is able to address the operation and function of microbial communities on a wide range of organizational levels.

Temperature-responsive PLLA/PNIPAM nanofibers for switchable release

Energy Technology Data Exchange (ETDEWEB)

Elashnikov, Roman; Slepička, Petr [Department of Solid State Engineering, University of Chemistry and Technology, Prague 166 28 (Czech Republic); Rimpelova, Silvie; Ulbrich, Pavel [Department of Biochemistry and Microbiology, University of Chemistry and Technology, 16628 Prague (Czech Republic); Švorčík, Vaclav [Department of Solid State Engineering, University of Chemistry and Technology, Prague 166 28 (Czech Republic); Lyutakov, Oleksiy, E-mail: lyutakoo@vscht.cz [Department of Solid State Engineering, University of Chemistry and Technology, Prague 166 28 (Czech Republic)

2017-03-01

Smart antimicrobial materials with on-demand drug release are highly desired for biomedical applications. Herein, we report about temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) nanospheres doped with crystal violet (CV) and incorporated into the poly-L-lactide (PLLA) nanofibers. The nanofibers were prepared by electrospinning, using different initial polymers ratios. The morphology of the nanofibers and polymers distribution in the nanofibers were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The interaction between PNIPAM and PLLA in the nanofibers was studied by Fourier transform infrared spectroscopy (FTIR) and its effect on the PNIPAM phase transition was also investigated. It was shown that by the changing of the environmental temperature across the lower critical solution temperature (LCST) of PNIPAM, the switchable wettability and controlled CV release can be achieved. The temperature-dependent release kinetics of CV from polymer nanofibers was investigated by ultraviolet-visible spectroscopy (UV–Vis). The temperature-responsive release of antibacterial CV was also tested for triggering of antibacterial activity, which was examined on Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli). Thus, the proposed material is promising value for controllable drug-release.

Multimodel Surface Temperature Responses to Removal of U.S. Sulfur Dioxide Emissions

Science.gov (United States)

Conley, A. J.; Westervelt, D. M.; Lamarque, J.-F.; Fiore, A. M.; Shindell, D.; Correa, G.; Faluvegi, G.; Horowitz, L. W.

2018-03-01

Three Earth System models are used to derive surface temperature responses to removal of U.S. anthropogenic SO2 emissions. Using multicentury perturbation runs with and without U.S. anthropogenic SO2 emissions, the local and remote surface temperature changes are estimated. In spite of a temperature drift in the control and large internal variability, 200 year simulations yield statistically significant regional surface temperature responses to the removal of U.S. SO2 emissions. Both local and remote surface temperature changes occur in all models, and the patterns of changes are similar between models for northern hemisphere land regions. We find a global average temperature sensitivity to U.S. SO2 emissions of 0.0055 K per Tg(SO2) per year with a range of (0.0036, 0.0078). We examine global and regional responses in SO4 burdens, aerosol optical depths (AODs), and effective radiative forcing (ERF). While changes in AOD and ERF are concentrated near the source region (United States), the temperature response is spread over the northern hemisphere with amplification of the temperature increase toward the Arctic. In all models, we find a significant response of dust concentrations, which affects the AOD but has no obvious effect on surface temperature. Temperature sensitivity to the ERF of U.S. SO2 emissions is found to differ from the models' sensitivity to radiative forcing of doubled CO2.

Temperature responses of exercizing dogs to infusion of electrolytes

Science.gov (United States)

Greenleaf, J. E.; Kozlowski, S.; Nazar, K.; Kaciuba-Uscilko, H.; Brzezinska, Z.

1974-01-01

The effect of infusions with solutions of various ionic and osmotic composition on exercise temperature responses was studied in dogs who do not regulate their temperature by sweating. The results suggest an association between plasma Na+ and Ca++ level within the normal physiological range and the control of body temperature during exercise.

Genetic dysbiosis: the role of microbial insults in chronic inflammatory diseases

Directory of Open Access Journals (Sweden)

Luigi Nibali

2014-02-01

Full Text Available Thousands of bacterial phylotypes colonise the human body and the host response to this bacterial challenge greatly influences our state of health or disease. The concept of infectogenomics highlights the importance of host genetic factors in determining the composition of human microbial biofilms and the response to this microbial challenge. We hereby introduce the term ‘genetic dysbiosis’ to highlight the role of human genetic variants affecting microbial recognition and host response in creating an environment conducive to changes in the normal microbiota. Such changes can, in turn, predispose to, and influence, diseases such as: cancer, inflammatory bowel disease, rheumatoid arthritis, psoriasis, bacterial vaginosis and periodontitis. This review presents the state of the evidence on host genetic factors affecting dysbiosis and microbial misrecognition (i.e. an aberrant response to the normal microbiota and highlights the need for further research in this area.

Elimination of pyraclostrobin by simultaneous microbial degradation coupled with the Fenton process in microbial fuel cells and the microbial community.

Science.gov (United States)

Zhao, Huanhuan; Kong, Chui-Hua

2018-06-01

The elimination of pyraclostrobin by simultaneous microbial degradation and Fenton oxidation was achieved in a microbial fuel cell (MFC) system. After 12 h of incubation, the removal rate of pyraclostrobin was 1.4 mg/L/h at the anode and 1.7 mg/L/h at the cathode. The pyraclostrobin concentration was less than the detection limit (0.1 mg/L) after 72 h at the anode and 24 h at the cathode. The air flow rate, temperature, and pH of the catholyte had significant effects on the generation of H 2 O 2 . The maximum production of H 2 O 2 was 1.2 mg/L after reaction for 20 h during the Fenton process. Microbial community analysis indicated that functional bacteria in the genera Chryseobacterium, Stenotrophomonas, Arcobacter, and Comamonas were predominant in the anodic biofilm. In conclusion, the MFC-Fenton system provides an effective approach for treating environmental contaminants. Copyright © 2018 Elsevier Ltd. All rights reserved.

Temperature-responsive chromatography for the separation of biomolecules.

Science.gov (United States)

Kanazawa, Hideko; Okano, Teruo

2011-12-09

Temperature-responsive chromatography for the separation of biomolecules utilizing poly(N-isopropylacrylamide) (PNIPAAm) and its copolymer-modified stationary phase is performed with an aqueous mobile phase without using organic solvent. The surface properties and function of the stationary phase are controlled by external temperature changes without changing the mobile-phase composition. This analytical system is based on nonspecific adsorption by the reversible transition of a hydrophilic-hydrophobic PNIPAAm-grafted surface. The driving force for retention is hydrophobic interaction between the solute molecules and the hydrophobized polymer chains on the stationary phase surface. The separation of the biomolecules, such as nucleotides and proteins was achieved by a dual temperature- and pH-responsive chromatography system. The electrostatic and hydrophobic interactions could be modulated simultaneously with the temperature in an aqueous mobile phase, thus the separation system would have potential applications in the separation of biomolecules. Additionally, chromatographic matrices prepared by a surface-initiated atom transfer radical polymerization (ATRP) exhibit a strong interaction with analytes, because the polymerization procedure forms a densely packed polymer, called a polymer brush, on the surfaces. The copolymer brush grafted surfaces prepared by ATRP was an effective tool for separating basic biomolecules by modulating the electrostatic and hydrophobic interactions. Applications of thermally responsive columns for the separations of biomolecules are reviewed here. Copyright © 2011 Elsevier B.V. All rights reserved.

The microbial fate of carbon in high-latitude seas: Impact of the microbial loop on oceanic uptake of CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Yager, P.L.

1996-12-31

This dissertation examines pelagic microbial processes in high-latitude seas, how they affect regional and global carbon cycling, and how they might respond to hypothesized changes in climate. Critical to these interests is the effect of cold temperature on bacterial activity. Also important is the extent to which marine biological processes in general impact the inorganic carbon cycle. The study area is the Northeast Water (NEW) Polynya, a seasonally-recurrent opening in the permanent ice situated over the northeastern Greenland continental shelf. This work was part of an international, multi-disciplinary research project studying carbon cycling in the coastal Arctic. The first chapter describes a simple model which links a complex marine food web to a simplified ocean and atmosphere. The second chapter investigates the inorganic carbon inventory of the summertime NEW Polynya surface waters to establish the effect of biological processes on the air-sea pCO{sub 2} gradient. The third and fourth chapters use a kinetic approach to examine microbial activities in the NEW Polynya as a function of temperature and dissolved organic substrate concentration, testing the so-called Pomeroy hypothesis that microbial activity is disproportionately reduced at low environmental temperatures owing to increased organic substrate requirements. Together, the suite of data collected on microbial activities, cell size, and grazing pressure suggest how unique survival strategies adopted by an active population of high-latitude bacteria may contribute to, rather than detract from, an efficient biological carbon pump.

Selective progressive response of soil microbial community to wild oat roots

Energy Technology Data Exchange (ETDEWEB)

DeAngelis, K.M.; Brodie, E.L.; DeSantis, T.Z.; Andersen, G.L.; Lindow, S.E.; Firestone, M.K.

2008-10-01

Roots moving through soil enact physical and chemical changes that differentiate rhizosphere from bulk soil, and the effects of these changes on soil microorganisms have long been a topic of interest. Use of a high-density 16S rRNA microarray (PhyloChip) for bacterial and archaeal community analysis has allowed definition of the populations that respond to the root within the complex grassland soil community; this research accompanies previously reported compositional changes, including increases in chitinase and protease specific activity, cell numbers and quorum sensing signal. PhyloChip results showed a significant change in 7% of the total rhizosphere microbial community (147 of 1917 taxa); the 7% response value was confirmed by16S rRNA T-RFLP analysis. This PhyloChip-defined dynamic subset was comprised of taxa in 17 of the 44 phyla detected in all soil samples. Expected rhizosphere-competent phyla, such as Proteobacteria and Firmicutes, were well represented, as were less-well-documented rhizosphere colonizers including Actinobacteria, Verrucomicrobia and Nitrospira. Richness of Bacteroidetes and Actinobacteria decreased in soil near the root tip compared to bulk soil, but then increased in older root zones. Quantitative PCR revealed {beta}-Proteobacteria and Actinobacteria present at about 10{sup 8} copies of 16S rRNA genes g{sup -1} soil, with Nitrospira having about 10{sup 5} copies g{sup -1} soil. This report demonstrates that changes in a relatively small subset of the soil microbial community are sufficient to produce substantial changes in function in progressively more mature rhizosphere zones.

Functional and compositional responses in soil microbial communities along two metal pollution gradients: does the level of historical pollution affect resistance against secondary stress?

NARCIS (Netherlands)

Azarbad, H.; Niklinska, M.; Nikiel, K.; van Straalen, N.M.; Röling, W.F.M.

2015-01-01

We examined how the exposure to secondary stressors affected the functional and compositional responses of microbial communities along two metal pollution gradients in Polish forests and whether responses were influenced by the level of metal pollution. Basal respiration rate and community

Effect of Temperature on Precipitation Rate of Calcium Carbonate Produced through Microbial Metabolic Process of Bio Materials

Directory of Open Access Journals (Sweden)

Prima Yane Putri

2016-09-01

Full Text Available Concrete is the most widely used construction material in civil engineering. But plain concrete is a brittle material and has little resistance to cracking. The cracking in concrete promotes deterioration such as the corrosion of reinforcing rebar, therefore, repair in filling the crack is often carried out. Recently, repair methods using bio-based materials associated with microbial metabolic processes leading to precipitation of calcium carbonate have been intensively studied. In this study, influencing factors on the precipitation rate depending on the constituents of bio-based material comprising yeast, glucose and calcium acetate mixed in tris buffer solution was examined for improving the rate of initial reactions. In addition, effect of temperature change on the amount of calcium carbonate precipitation was also investigated. The precipitates were identified by X-ray diffraction. It was shown that the increase of temperature lead to a change on calcium carbonate precipitation and caused the pH decrease under 7.0.

Using Real-time Quantitative PCR to Examine the Dynamics of Soil Fungi and Bacteria in Response to Ecosystem Warming

Science.gov (United States)

As atmospheric trace gas concentrations and global temperatures climb, scientists are challenged to determine how microbial communities may mediate plant response to future climate change. To this end, a Temperature Free-Air Controlled Enrichment (T-FACE) experiment was implemented in a spring wheat...

Physiological and biochemical responses to low temperature stress ...

African Journals Online (AJOL)

Cuttings of three hybrid clones of P. ussuriensis × P. deltoides were exposed to different low temperatures (cold and freezing) for 24 h, or consecutive low temperatures (5°C, 0 to 120 h), to determine physiological and biochemical responses to cold stress in these woody plants. Soluble sugar and protein contents increased ...

Quantitative analysis of circadian single cell oscillations in response to temperature.

Science.gov (United States)

Abraham, Ute; Schlichting, Julia Katharina; Kramer, Achim; Herzel, Hanspeter

2018-01-01

Body temperature rhythms synchronize circadian oscillations in different tissues, depending on the degree of cellular coupling: the responsiveness to temperature is higher when single circadian oscillators are uncoupled. So far, the role of coupling in temperature responsiveness has only been studied in organotypic tissue slices of the central circadian pacemaker, because it has been assumed that peripheral target organs behave like uncoupled multicellular oscillators. Since recent studies indicate that some peripheral tissues may exhibit cellular coupling as well, we asked whether peripheral network dynamics also influence temperature responsiveness. Using a novel technique for long-term, high-resolution bioluminescence imaging of primary cultured cells, exposed to repeated temperature cycles, we were able to quantitatively measure period, phase, and amplitude of central (suprachiasmatic nuclei neuron dispersals) and peripheral (mouse ear fibroblasts) single cell oscillations in response to temperature. Employing temperature cycles of different lengths, and different cell densities, we found that some circadian characteristics appear cell-autonomous, e.g. period responses, while others seem to depend on the quality/degree of cellular communication, e.g. phase relationships, robustness of the oscillation, and amplitude. Overall, our findings indicate a strong dependence on the cell's ability for intercellular communication, which is not only true for neuronal pacemakers, but, importantly, also for cells in peripheral tissues. Hence, they stress the importance of comparative studies that evaluate the degree of coupling in a given tissue, before it may be used effectively as a target for meaningful circadian manipulation.

Microbial biogeography: putting microorganisms on the map.

Science.gov (United States)

Martiny, Jennifer B Hughes; Bohannan, Brendan J M; Brown, James H; Colwell, Robert K; Fuhrman, Jed A; Green, Jessica L; Horner-Devine, M Claire; Kane, Matthew; Krumins, Jennifer Adams; Kuske, Cheryl R; Morin, Peter J; Naeem, Shahid; Ovreås, Lise; Reysenbach, Anna-Louise; Smith, Val H; Staley, James T

2006-02-01

We review the biogeography of microorganisms in light of the biogeography of macroorganisms. A large body of research supports the idea that free-living microbial taxa exhibit biogeographic patterns. Current evidence confirms that, as proposed by the Baas-Becking hypothesis, 'the environment selects' and is, in part, responsible for spatial variation in microbial diversity. However, recent studies also dispute the idea that 'everything is everywhere'. We also consider how the processes that generate and maintain biogeographic patterns in macroorganisms could operate in the microbial world.

Shifts in identity and activity of methanotrophs in arctic lake sediments in response to temperature changes

Science.gov (United States)

He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

2012-01-01

Methane (CH4) flux to the atmosphere is mitigated via microbial CH4 oxidation in sediments and water. As arctic temperaturesincrease, understanding the effects of temperature on the activity and identity of methanotrophs in arctic lake sediments is importantto predicting future CH4 emissions. We used DNA-based stable-isotope probing (SIP), quantitative PCR (Q-PCR), andpyrosequencing analyses to identify and characterize methanotrophic communities active at a range of temperatures (4°C, 10°C,and 21°C) in sediments (to a depth of 25 cm) sampled from Lake Qalluuraq on the North Slope of Alaska. CH4 oxidation activitywas measured in microcosm incubations containing sediments at all temperatures, with the highest CH4 oxidation potential of37.5 mol g1 day1 in the uppermost (depth, 0 to 1 cm) sediment at 21°C after 2 to 5 days of incubation. Q-PCR of pmoA and ofthe 16S rRNA genes of type I and type II methanotrophs, and pyrosequencing of 16S rRNA genes in 13C-labeled DNA obtained bySIP demonstrated that the type I methanotrophs Methylobacter, Methylomonas, and Methylosoma dominated carbon acquisitionfrom CH4 in the sediments. The identity and relative abundance of active methanotrophs differed with the incubation temperature.Methylotrophs were also abundant in the microbial community that derived carbon from CH4, especially in the deeper sediments(depth, 15 to 20 cm) at low temperatures (4°C and 10°C), and showed a good linear relationship (R0.82) with the relativeabundances of methanotrophs in pyrosequencing reads. This study describes for the first time how methanotrophiccommunities in arctic lake sediments respond to temperature variations.

Effect of temperature on shelf life, chemical and microbial properties ...

African Journals Online (AJOL)

use

2011-11-23

Nov 23, 2011 ... and extrinsic factors (microbial quality of raw milk, production phases, ripening and packaging conditions, etc) (Prencipe et al., 2010; Hosny et al., 2011; Giammanco et al., 2011). Among the dairy products, cheese is the only product really susceptible to fungal growth and also production of mycotoxins.

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

KAUST Repository

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

2011-01-01

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

Sound characteristics of Terapon jorbua as a response to temperature changes

Science.gov (United States)

Amron; Jaya, I.; Hestirianoto, T.; Juterzenka, K. v.

2017-10-01

The change of water temperature has potential impact on the behavior of aquatic animal including fish which generated by their sound productivity and characteristics. This research aimed to study the response of sound productivity and characteristics of Terapon jorbua to temperature change. As a response to temperature increase, T. jorbua to have decreased the number of sound productivity. Two characteristic parameters of fish sound, i.e. intensity and frequency as were quadratic increased during the water temperature rises. In contrast, pulse duration was quadratic decreased.

Photosynthetic temperature responses of tree species in Rwanda: evidence of pronounced negative effects of high temperature in montane rainforest climax species

Science.gov (United States)

Vårhammar, Angelica; Wallin, Göran; McLean, Christopher M.; Dusenge, Mirindi Eric; Medlyn, Belinda E.; Hasper, Thomas B.; Nsabimana, Donat; Uddling, Johan

2015-04-01

The sensitivity of photosynthetic metabolism to temperature has been identified as a key uncertainty for projecting the magnitude of the terrestrial feedback on future climate change. While temperature responses of photosynthetic capacities have been comparatively well investigated in temperate species, the responses of tropical tree species remain unexplored. We compared the responses of seedlings of native cold-adapted tropical montane rainforest tree species to exotic warm-adapted plantation species, all growing in an intermediate temperature common garden in Rwanda. Leaf gas exchange responses to CO2 at different temperatures (20 - 40 C) were used to assess the temperature responses of biochemical photosynthetic capacities. Analyses revealed a lower optimum temperature for photosynthetic electron transport rates than for Rubisco carboxylation rates, along with lower electron transport optima in the native cold-adapted than in the exotic warm-adapted species. The photosynthetic optimum temperatures were generally exceeded by daytime peak leaf temperatures, in particular in the native montane rainforest climax species. This study thus provides evidence of pronounced negative effects of high temperature in tropical trees and indicates high susceptibility of montane rainforest climax species to future global warming. (Reference: New Phytologist, in press)

Temperature-Responsive Anisotropic Slippery Surface for Smart Control of the Droplet Motion.

Science.gov (United States)

Wang, By Lili; Heng, Liping; Jiang, Lei

2018-02-28

Development of stimulus-responsive anisotropic slippery surfaces is important because of the high demand for such materials in the field of liquid directional-driven systems. However, current studies in the field of slippery surfaces are mainly conducted to prepare isotropic slippery surfaces. Although we have developed electric-responsive anisotropic slippery surfaces that enable smart control of the droplet motion, there remain challenges for designing temperature-responsive anisotropic slippery surfaces to control the liquid droplet motion on the surface and in the tube. In this work, temperature-responsive anisotropic slippery surfaces have been prepared by using paraffin, a thermo-responsive phase-transition material, as a lubricating fluid and directional porous polystyrene (PS) films as the substrate. The smart regulation of the droplet motion of several liquids on this surface was accomplished by tuning the substrate temperature. The uniqueness of this surface lies in the use of an anisotropic structure and temperature-responsive lubricating fluids to achieve temperature-driven smart control of the anisotropic motion of the droplets. Furthermore, this surface was used to design temperature-driven anisotropic microreactors and to manipulate liquid transfer in tubes. This work advances the understanding of the principles underlying anisotropic slippery surfaces and provides a promising material for applications in the biochip and microreactor system.

Microbial dynamics during azo dye degradation in a UASB reactor supplied with yeast extract.

Science.gov (United States)

Silva, S Q; Silva, D C; Lanna, M C S; Baeta, B E L; Aquino, S F

2014-01-01

The present work aimed to investigate the microbial dynamics during the anaerobic treatment of the azo dye blue HRFL in bench scale upflow anaerobic sludge bed (UASB) reactor operated at ambient temperature. Sludge samples were collected under distinct operational phases, when the reactor were stable (low variation of color removal), to assess the effect of glucose and yeast extract as source of carbon and redox mediators, respectively. Reactors performance was evaluated based on COD (chemical oxygen demand) and color removal. The microbial dynamics were investigated by PCR-DGGE (Polimerase Chain Reaction - Denaturing Gradient of Gel Electrophoresis) technique by comparing the 16S rDNA profiles among samples. The results suggest that the composition of microorganisms changed from the beginning to the end of the reactor operation, probably in response to the presence of azo dye and/or its degradation byproducts. Despite the highest efficiency of color removal was observed in the presence of 500 mg/L of yeast extract (up to 93%), there were no differences regarding the microbial profiles that could indicate a microbial selection by the yeast extract addition. On the other hand Methosarcina barkeri was detected only in the end of operation when the best efficiencies on color removal occurred. Nevertheless the biomass selection observed in the last stages of UASB operation is probably a result of the washout of the sludge in response of accumulation of aromatic amines which led to tolerant and very active biomass that contributed to high efficiencies on color removal.

Microbial fuel cells as power supply of a low-power temperature sensor

Science.gov (United States)

Khaled, Firas; Ondel, Olivier; Allard, Bruno

2016-02-01

Microbial fuel cells (MFCs) show great promise as a concomitant process for water treatment and as renewable energy sources for environmental sensors. The small energy produced by MFCs and the low output voltage limit the applications of MFCs. Specific converter topologies are required to step-up the output voltage of a MFC. A Power Management Unit (PMU) is proposed for operation at low input voltage and at very low power in a completely autonomous way to capture energy from MFCs with the highest possible efficiency. The application of sensors for monitoring systems in remote locations is an important approach. MFCs could be an alternative energy source in this case. Powering a sensor with MFCs may prove the fact that wastewater may be partly turned into renewable energy for realistic applications. The Power Management Unit is demonstrated for 3.6 V output voltage at 1 mW continuous power, based on a low-cost 0.7-L MFC. A temperature sensor may operate continuously on 2-MFCs in continuous flow mode. A flyback converter under discontinuous conduction mode is also tested to power the sensor. One continuously fed MFC was able to efficiently and continuously power the sensor.

Interconnection of Key Microbial Functional Genes for Enhanced Benzo[a]pyrene Biodegradation in Sediments by Microbial Electrochemistry.

Science.gov (United States)

Yan, Zaisheng; He, Yuhong; Cai, Haiyuan; Van Nostrand, Joy D; He, Zhili; Zhou, Jizhong; Krumholz, Lee R; Jiang, He-Long

2017-08-01

Sediment microbial fuel cells (SMFCs) can stimulate the degradation of polycyclic aromatic hydrocarbons in sediments, but the mechanism of this process is poorly understood at the microbial functional gene level. Here, the use of SMFC resulted in 92% benzo[a]pyrene (BaP) removal over 970 days relative to 54% in the controls. Sediment functions, microbial community structure, and network interactions were dramatically altered by the SMFC employment. Functional gene analysis showed that c-type cytochrome genes for electron transfer, aromatic degradation genes, and extracellular ligninolytic enzymes involved in lignin degradation were significantly enriched in bulk sediments during SMFC operation. Correspondingly, chemical analysis of the system showed that these genetic changes resulted in increases in the levels of easily oxidizable organic carbon and humic acids which may have resulted in increased BaP bioavailability and increased degradation rates. Tracking microbial functional genes and corresponding organic matter responses should aid mechanistic understanding of BaP enhanced biodegradation by microbial electrochemistry and development of sustainable bioremediation strategies.

Metabolome Integrated Analysis of High-Temperature Response in Pinus radiata

Directory of Open Access Journals (Sweden)

Mónica Escandón

2018-04-01

Full Text Available The integrative omics approach is crucial to identify the molecular mechanisms underlying high-temperature response in non-model species. Based on future scenarios of heat increase, Pinus radiata plants were exposed to a temperature of 40°C for a period of 5 days, including recovered plants (30 days after last exposure to 40°C in the analysis. The analysis of the metabolome using complementary mass spectrometry techniques (GC-MS and LC-Orbitrap-MS allowed the reliable quantification of 2,287 metabolites. The analysis of identified metabolites and highlighter metabolic pathways across heat time exposure reveal the dynamism of the metabolome in relation to high-temperature response in P. radiata, identifying the existence of a turning point (on day 3 at which P. radiata plants changed from an initial stress response program (shorter-term response to an acclimation one (longer-term response. Furthermore, the integration of metabolome and physiological measurements, which cover from the photosynthetic state to hormonal profile, suggests a complex metabolic pathway interaction network related to heat-stress response. Cytokinins (CKs, fatty acid metabolism and flavonoid and terpenoid biosynthesis were revealed as the most important pathways involved in heat-stress response in P. radiata, with zeatin riboside (ZR and isopentenyl adenosine (iPA as the key hormones coordinating these multiple and complex interactions. On the other hand, the integrative approach allowed elucidation of crucial metabolic mechanisms involved in heat response in P. radiata, as well as the identification of thermotolerance metabolic biomarkers (L-phenylalanine, hexadecanoic acid, and dihydromyricetin, crucial metabolites which can reschedule the metabolic strategy to adapt to high temperature.

Microbial O{sub 2} consumption in the Aespoe tunnel

Energy Technology Data Exchange (ETDEWEB)

Kotelnikova, S.; Pedersen, Karsten [Goeteborg Univ. (Sweden). Dept. of Cell and Molecular Biology, Microbiology

1998-04-01

The report presents data on microbial O{sub 2} reduction activities by microorganisms obtained with different techniques: Winkler method, gas chromatography, most probable numbering, enrichment technique, inhibitor analysis and radiotracer measurements. The samples were collected from boreholes and open funnel ponds at Aespoe in 1996-1998. The evaluation of the microbial activities in open ponds predicts the future microbial activities after the O{sub 2} intrusion around the future repository. The metabolic potential of the microbial population inhabiting groundwater was evaluated on the basis of electron donors available and microbial 16S rRNA gene diversity. The contribution of different microbial groups to the O{sub 2} reduction was elucidated using specific inhibitors selectively affecting different microbial groups. Our experiments show that microbial O{sub 2} reduction occurs in deep groundwater. Carbon dioxide was produced concurrently with O{sub 2} reduction confirming the biogenic nature of the reduction. The populations developed O{sub 2} reduction rates and capacity depending on the initial concentration of dissolved O{sub 2} reduction. Rates of O{sub 2} reduction ranged from 0.32 to 4.5 {mu}M/day. Depending on temperature and the type of groundwater the approximate time needed for consumption of 500 {mu}M of dissolved O{sub 2} ranged from 0.31 to 3.99 years. After approximately a 2 weeks period the microbial population in vitro was able to consume O{sub 2} both at 30 deg C and 60 deg C. At 16 deg C no delay in O{sub 2} consumption was observed. Our results demonstrated that methanotrophs survive in deep groundwater and that they were induced by O{sub 2}. Some bacteria use Hg or CH{sub 4} as electron donor instead of organic matter, which means that microbial O{sub 2} reduction will occur also in deep groundwaters where the availability of organic carbon is limited. Specific CH{sub 4} oxidation rates ranged between 3.00 and 220 nM CH{sub 4} per litre per

Time response of temperature sensors using neural networks

International Nuclear Information System (INIS)

Santos, Roberto Carlos dos

2010-01-01

In a PWR nuclear power plant, the primary coolant temperature and feedwater temperature are measured using RTDs (Resistance Temperature Detectors). These RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs is characterized by a single parameter called the Plunge Time Constant defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature. Nuclear reactor service conditions are difficult to reproduce in the laboratory, and an in-situ test method called LCSR (Loop Current Step Response) test was developed to measure remotely the response time of RTDs. >From this test, the time constant of the sensor is identified by means of the LCSR transformation that involves the dynamic response modal time constants determination using a nodal heat-transfer model. This calculation is not simple and requires specialized personnel. For this reason an Artificial Neural Network has been developed to predict the time constant of RTD from LCSR test transient. It eliminates the transformations involved in the LCSR application. A series of LCSR tests on RTDs generates the response transients of the sensors, the input data of the networks. Plunge tests are used to determine the time constants of the RTDs, the desired output of the ANN, trained using these sets of input/output data. This methodology was firstly applied to theoretical data simulating 10 RTDs with different time constant values, resulting in an average error of about 0.74 %. Experimental data from three different RTDs was used to predict time constant resulting in a maximum error of 3,34 %. The time constants values predicted from ANN were compared with those obtained from traditional way resulting in an average error of about 18 % and that shows the network is able to predict accurately the sensor time constant. (author)

Temperature induced decoupling of enzymatic hydrolysis and carbon remineralization in long-term incubations of Arctic and temperate sediments

DEFF Research Database (Denmark)

Robador, Alberto; Brüchert, Volker; Steen, Andrew

2010-01-01

explored the temperature sensitivity of enzymatic hydrolysis and its connection to subsequent steps in anoxic organic carbon degradation in long-term incubations of sediments from the Arctic and the North Sea. These sediments were incubated under anaerobic conditions for 24 months at temperatures of 0, 10......, and 20 ºC. The short-term temperature response of the active microbial community was tested in temperature gradient block incubations. The temperature optimum of extracellular enzymatic hydrolysis, as measured with a polysaccharide (chondroitin sulfate), differed between Arctic and temperate habitats...

Review of resistance temperature detector time response characteristics. Safety evaluation report

International Nuclear Information System (INIS)

1981-08-01

A Resistance Temperature Detector (RTD) is used extensively for monitoring water temperatures in nuclear reactor plants. The RTD element does not respond instantaneously to changes in water temperature, but rather there is a time delay before the element senses the temperature change, and in nuclear reactors this delay must be factored into the computation of safety setpoints. For this reason it is necessary to have an accurate description of the RTD time response. This report is a review of the current state of the art of describing and measuring this time response

Microbial ecology and biogeochemistry of continental Antarctic soils.

Science.gov (United States)

Cowan, Don A; Makhalanyane, Thulani P; Dennis, Paul G; Hopkins, David W

2014-01-01

The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbor microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths) possess a genetic capacity for nitrogen and carbon cycling, polymer degradation, and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

Soil microbial community responses to antibiotic-contaminated manure under different soil moisture regimes.

Science.gov (United States)

Reichel, Rüdiger; Radl, Viviane; Rosendahl, Ingrid; Albert, Andreas; Amelung, Wulf; Schloter, Michael; Thiele-Bruhn, Sören

2014-01-01

Sulfadiazine (SDZ) is an antibiotic frequently administered to livestock, and it alters microbial communities when entering soils with animal manure, but understanding the interactions of these effects to the prevailing climatic regime has eluded researchers. A climatic factor that strongly controls microbial activity is soil moisture. Here, we hypothesized that the effects of SDZ on soil microbial communities will be modulated depending on the soil moisture conditions. To test this hypothesis, we performed a 49-day fully controlled climate chamber pot experiments with soil grown with Dactylis glomerata (L.). Manure-amended pots without or with SDZ contamination were incubated under a dynamic moisture regime (DMR) with repeated drying and rewetting changes of >20 % maximum water holding capacity (WHCmax) in comparison to a control moisture regime (CMR) at an average soil moisture of 38 % WHCmax. We then monitored changes in SDZ concentration as well as in the phenotypic phospholipid fatty acid and genotypic 16S rRNA gene fragment patterns of the microbial community after 7, 20, 27, 34, and 49 days of incubation. The results showed that strongly changing water supply made SDZ accessible to mild extraction in the short term. As a result, and despite rather small SDZ effects on community structures, the PLFA-derived microbial biomass was suppressed in the SDZ-contaminated DMR soils relative to the CMR ones, indicating that dynamic moisture changes accelerate the susceptibility of the soil microbial community to antibiotics.

Selected durability studies of geopolymer concrete with respect to carbonation, elevated temperature, and microbial induced corrosion

Science.gov (United States)

Badar, Mohammad Sufian

This thesis reports a comprehensive study related to the experimental evaluation of carbonation in reinforced geopolymer concrete, the evaluation of geopolymer concretes at elevated temperature, and the resistance of geopolymer concrete to microbial induced corrosion (MIC). Carbonation: Reinforced concretes, made of geopolymer, prepared from two class F fly ashes and one class C fly ash, were subjected to accelerated carbonation treatment for a period of 450 days. Electrochemical, microstructure and pore structure examinations were performed to evaluate the effect of corrosion caused due to carbonation. GPC specimens prepared from class F fly ash exhibited lower corrosion rates by a factor of 21, and higher pH values (pH>12) when compared with concrete specimens prepared from class C Fly ash (GPCMN). Microstructure and pore characterization of GPC prepared using class F fly ash revealed lower porosity by a factor of 2.5 as compared with thier counterparts made using GPC-MN. The superior performace of GPC prepared with the class F fly ash could be attributed to the dense pore structure and formation of the protective layer of calcium and sodium alumino silicate hydrates (C/N-A-S-H) geopolymeric gels around the steel reinforcement. Elevated Temperature: Geopolymers are an emerging class of cementitious binders which possess a potential for high temperature resistance that could possibly be utilized in applications such as nozzles, aspirators and refractory linings. This study reports on the results of an investigation into the performance of a fly ash based geopolymer binder in high temperature environments. Geopolymer concrete (GPC) was prepared using eleven types of fly ashes obtained from four countries. High content alumina and silica sand was used in the mix for preparing GPC. GPC was subjected to thermal shock tests following ASTM C 1100-88. The GPC samples prepared with tabular alumina were kept at 1093° C and immediately quenched in water. GPC specimens

Photosynthetic temperature responses of tree species in Rwanda: evidence of pronounced negative effects of high temperature in montane rainforest climax species.

Science.gov (United States)

Vårhammar, Angelica; Wallin, Göran; McLean, Christopher M; Dusenge, Mirindi Eric; Medlyn, Belinda E; Hasper, Thomas B; Nsabimana, Donat; Uddling, Johan

2015-05-01

The sensitivity of photosynthetic metabolism to temperature has been identified as a key uncertainty for projecting the magnitude of the terrestrial feedback on future climate change. While temperature responses of photosynthetic capacities have been comparatively well investigated in temperate species, the responses of tropical tree species remain unexplored. We compared the responses of seedlings of native cold-adapted tropical montane rainforest tree species with those of exotic warm-adapted plantation species, all growing in an intermediate temperature common garden in Rwanda. Leaf gas exchange responses to carbon dioxide (CO2 ) at different temperatures (20-40°C) were used to assess the temperature responses of biochemical photosynthetic capacities. Analyses revealed a lower optimum temperature for photosynthetic electron transport rates than for Rubisco carboxylation rates, along with lower electron transport optima in the native cold-adapted than in the exotic warm-adapted species. The photosynthetic optimum temperatures were generally exceeded by daytime peak leaf temperatures, in particular in the native montane rainforest climax species. This study thus provides evidence of pronounced negative effects of high temperature in tropical trees and indicates high susceptibility of montane rainforest climax species to future global warming. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Influence of temperature in polymethylmethacrylate (PMMA) dosemeters response

International Nuclear Information System (INIS)

Napolitano, Celia Marina; Ferreira, Danilo Cardenuto; Camargo, Fabio de; Goncalves, Josemary Angelica Correa; Tobias, Carmen Cecilia Bueno

2005-01-01

The use of gamma irradiation sterilization processes in medical products and food preservation has encouraged the emergence of industrial facilities responsible for generation of doses as high as a few dozen kGy. The characterization of this radiation field requires the use of dosimeters with high spatial resolution, high resistance to radiation damage, maintenance of information absorbed doses at a time suitable for the analysis and processing of data, easy handling, etc. The dosimeters that meet most of these requirements are based on polymethylmethacrylate (PMMA) with dyes sensitive to radiation. The dose that can be measured with these dosimeters extends from 100Gy to 50kGy, with the estimated accuracies by manufacturers from 2 to 3%. However, in practice, there are procedures that require irradiation in different conditions of temperature, which results in changes in the response of the dosimeter. This way, considering the irradiations made in the center of radiation technology of Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP - Brazilian nuclear and energy research institute -, has studied the effect of temperature on the response of routine dosimeters PMMA type where the operational characteristics of Gammachrome YR dosimeters type and Red Perspex are being investigated respect to temperature and dose, whose results will be presented in this paper

Evaluation of microbial community composition in thermophilic methane-producing incubation of production water from a high-temperature oil reservoir.

Science.gov (United States)

Zhou, Fang; Mbadinga, Serge Maurice; Liu, Jin-Feng; Gu, Ji-Dong; Mu, Bo-Zhong

2013-01-01

Investigation of petroleum microbes is fundamental for the development and utilization of oil reservoirs' microbial resources, and also provides great opportunities for research and development of bio-energy. Production water from a high-temperature oil reservoir was incubated anaerobically at 55 degrees C for more than 400 days without amendment of any nutrients. Over the time of incubation, about 1.6 mmol of methane and up to 107 micromol of hydrogen (H2) were detected in the headspace. Methane formation indicated that methanogenesis was likely the predominant process in spite of the presence of 23.4 mM SO4(2-) in the production water. Microbial community composition of the incubation was characterized by means of 16S rRNA gene clone libraries construction. Bacterial composition changed from Pseudomonales as the dominant population initially to Hydrogenophilales-related microorganisms affiliated to Petrobacter spp. closely. After 400 days of incubation, other bacterial members detected were related to Anareolineales, beta-, gamma-, and delta-Proteobacteria. The archaeal composition of the original production water was essentially composed of obligate acetoclastic methanogens of the genus Methanosaeta, but the incubation was predominantly composed of CO2-reducing methanogens of the genus Methanothermobacter and Crenarchaeotes-related microorganisms. Our results suggest that methanogenesis could be more active than expected in oil reservoir environments and methane formation from CO2-reduction played a significant role in the methanogenic community. This conclusion is consistent with the predominant role played by H2-oxidizing methanogens in the methanogenic conversion of organic matter in high-temperature petroleum reservoirs.

Assessment of the Microbial Control Measures for the Temperature and Humidity Control Subsystem Condensing Heat Exchanger of the International Space Station

Science.gov (United States)

Roman, Monsi C.; Steele, John W.; Marsh, Robert W.; Callahan, David M.; VonJouanne, Roger G.

1999-01-01

In August 1997 NASA/ Marshall Space Flight Center (MSFC) began a test with the objective of monitoring the growth of microorganisms on material simulating the surface of the International Space Station (ISS) Temperature and Humidity Control (THC) Condensing Heat Exchanger (CHX). The test addressed the concerns of potential uncontrolled microbial growth on the surface of the THC CHX subsystem. For this study, humidity condensate from a closed manned environment was used as a direct challenge to the surfaces of six cascades in a test set-up. The condensate was collected using a Shuttle-type CHX within the MSFC End-Use Equipment Testing Facility. Panels in four of the six cascades tested were coated with the ISS CHX silver impregnated hydrophilic coating. The remainder two cascade panels were coated with the hydrophilic coating without the antimicrobial component, silver. Results of the fourteen-month study are discussed in this paper. The effects on the microbial population when drying vs. not-drying the simulated THC CHX surface are also discussed.

Soil Microbial Responses to Elevated CO2 and O3 in a Nitrogen-Aggrading Agroecosystem

Science.gov (United States)

Cheng, Lei; Booker, Fitzgerald L.; Burkey, Kent O.; Tu, Cong; Shew, H. David; Rufty, Thomas W.; Fiscus, Edwin L.; Deforest, Jared L.; Hu, Shuijin

2011-01-01

Climate change factors such as elevated atmospheric carbon dioxide (CO2) and ozone (O3) can exert significant impacts on soil microbes and the ecosystem level processes they mediate. However, the underlying mechanisms by which soil microbes respond to these environmental changes remain poorly understood. The prevailing hypothesis, which states that CO2- or O3-induced changes in carbon (C) availability dominate microbial responses, is primarily based on results from nitrogen (N)-limiting forests and grasslands. It remains largely unexplored how soil microbes respond to elevated CO2 and O3 in N-rich or N-aggrading systems, which severely hinders our ability to predict the long-term soil C dynamics in agroecosystems. Using a long-term field study conducted in a no-till wheat-soybean rotation system with open-top chambers, we showed that elevated CO2 but not O3 had a potent influence on soil microbes. Elevated CO2 (1.5×ambient) significantly increased, while O3 (1.4×ambient) reduced, aboveground (and presumably belowground) plant residue C and N inputs to soil. However, only elevated CO2 significantly affected soil microbial biomass, activities (namely heterotrophic respiration) and community composition. The enhancement of microbial biomass and activities by elevated CO2 largely occurred in the third and fourth years of the experiment and coincided with increased soil N availability, likely due to CO2-stimulation of symbiotic N2 fixation in soybean. Fungal biomass and the fungi∶bacteria ratio decreased under both ambient and elevated CO2 by the third year and also coincided with increased soil N availability; but they were significantly higher under elevated than ambient CO2. These results suggest that more attention should be directed towards assessing the impact of N availability on microbial activities and decomposition in projections of soil organic C balance in N-rich systems under future CO2 scenarios. PMID:21731722

Extended exposure to elevated temperature affects escape response behaviour in coral reef fishes

Directory of Open Access Journals (Sweden)

Donald T. Warren

2017-08-01

Full Text Available The threat of predation, and the prey’s response, are important drivers of community dynamics. Yet environmental temperature can have a significant effect on predation avoidance techniques such as fast-start performance observed in marine fishes. While it is known that temperature increases can influence performance and behaviour in the short-term, little is known about how species respond to extended exposure during development. We produced a startle response in two species of damselfish, the lemon damsel Pomacentrus moluccensis, and the Ambon damselfish Pomacentrus amboinensis, by the repeated use of a drop stimulus. We show that the length of thermal exposure of juveniles to elevated temperature significantly affects this escape responses. Short-term (4d exposure to warmer temperature affected directionality and responsiveness for both species. After long-term (90d exposure, only P. moluccensis showed beneficial plasticity, with directionality returning to control levels. Responsiveness also decreased in both species, possibly to compensate for higher temperatures. There was no effect of temperature or length of exposure on latency to react, maximum swimming speed, or escape distance suggesting that the physical ability to escape was maintained. Evidence suggests that elevated temperature may impact some fish species through its effect on the behavioural responses while under threat rather than having a direct influence on their physical ability to perform an effective escape response.

Complex terrain influences ecosystem carbon responses to temperature and precipitation

Science.gov (United States)

Reyes, W. M.; Epstein, H. E.; Li, X.; McGlynn, B. L.; Riveros-Iregui, D. A.; Emanuel, R. E.

2017-08-01

Terrestrial ecosystem responses to temperature and precipitation have major implications for the global carbon cycle. Case studies demonstrate that complex terrain, which accounts for more than 50% of Earth's land surface, can affect ecological processes associated with land-atmosphere carbon fluxes. However, no studies have addressed the role of complex terrain in mediating ecophysiological responses of land-atmosphere carbon fluxes to climate variables. We synthesized data from AmeriFlux towers and found that for sites in complex terrain, responses of ecosystem CO2 fluxes to temperature and precipitation are organized according to terrain slope and drainage area, variables associated with water and energy availability. Specifically, we found that for tower sites in complex terrain, mean topographic slope and drainage area surrounding the tower explained between 51% and 78% of site-to-site variation in the response of CO2 fluxes to temperature and precipitation depending on the time scale. We found no such organization among sites in flat terrain, even though their flux responses exhibited similar ranges. These results challenge prevailing conceptual framework in terrestrial ecosystem modeling that assumes that CO2 fluxes derive from vertical soil-plant-climate interactions. We conclude that the terrain in which ecosystems are situated can also have important influences on CO2 responses to temperature and precipitation. This work has implications for about 14% of the total land area of the conterminous U.S. This area is considered topographically complex and contributes to approximately 15% of gross ecosystem carbon production in the conterminous U.S.

Relative contributions of microbial and infrastructure heat at a crude oil-contaminated site

Science.gov (United States)

Warren, Ean; Bekins, Barbara A.

2018-04-01

Biodegradation of contaminants can increase the temperature in the subsurface due to heat generated from exothermic reactions, making temperature observations a potentially low-cost approach for determining microbial activity. For this technique to gain more widespread acceptance, it is necessary to better understand all the factors affecting the measured temperatures. Biodegradation has been occurring at a crude oil-contaminated site near Bemidji, Minnesota for 39 years, creating a quasi-steady-state plume of contaminants and degradation products. A model of subsurface heat generation and transport helps elucidate the contribution of microbial and infrastructure heating to observed temperature increases at this site. We created a steady-state, two-dimensional, heat transport model using previous-published parameter values for physical, chemical and biodegradation properties. Simulated temperature distributions closely match the observed average annual temperatures measured in the contaminated area at the site within less than 0.2 °C in the unsaturated zone and 0.4 °C in the saturated zone. The model results confirm that the observed subsurface heat from microbial activity is due primarily to methane oxidation in the unsaturated zone resulting in a 3.6 °C increase in average annual temperature. Another important source of subsurface heat is from the active, crude-oil pipelines crossing the site. The pipelines impact temperatures for a distance of 200 m and contribute half the heat. Model results show that not accounting for the heat from the pipelines leads to overestimating the degradation rates by a factor of 1.7, demonstrating the importance of identifying and quantifying all heat sources. The model results also highlighted a zone where previously unknown microbial activity is occurring at the site.

Responses of microbial community functional structures to pilot-scale uranium in situ bioremediation

Energy Technology Data Exchange (ETDEWEB)

Xu, M.; Wu, W.-M.; Wu, L.; He, Z.; Van Nostrand, J.D.; Deng, Y.; Luo, J.; Carley, J.; Ginder-Vogel, M.; Gentry, T.J.; Gu, B.; Watson, D.; Jardine, P.M.; Marsh, T.L.; Tiedje, J.M.; Hazen, T.C.; Criddle, C.S.; Zhou, J.

2010-02-15

A pilot-scale field test system with an inner loop nested within an outer loop was constructed for in situ U(VI) bioremediation at a US Department of Energy site, Oak Ridge, TN. The outer loop was used for hydrological protection of the inner loop where ethanol was injected for biostimulation of microorganisms for U(VI) reduction/immobilization. After 2 years of biostimulation with ethanol, U(VI) levels were reduced to below drinking water standard (<30 {micro}gl{sup -1}) in the inner loop monitoring wells. To elucidate the microbial community structure and functions under in situ uranium bioremediation conditions, we used a comprehensive functional gene array (GeoChip) to examine the microbial functional gene composition of the sediment samples collected from both inner and outer loop wells. Our study results showed that distinct microbial communities were established in the inner loop wells. Also, higher microbial functional gene number, diversity and abundance were observed in the inner loop wells than the outer loop wells. In addition, metal-reducing bacteria, such as Desulfovibrio, Geobacter, Anaeromyxobacter and Shewanella, and other bacteria, for example, Rhodopseudomonas and Pseudomonas, are highly abundant in the inner loop wells. Finally, the richness and abundance of microbial functional genes were highly correlated with the mean travel time of groundwater from the inner loop injection well, pH and sulfate concentration in groundwater. These results suggest that the indigenous microbial communities can be successfully stimulated for U bioremediation in the groundwater ecosystem, and their structure and performance can be manipulated or optimized by adjusting geochemical and hydrological conditions.

Temperature- and light-responsive smart polymer materials.

Science.gov (United States)

Jochum, Florian D; Theato, Patrick

2013-09-07

Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness.

Deep subsurface microbial processes

Science.gov (United States)

Lovley, D.R.; Chapelle, F.H.

1995-01-01

Information on the microbiology of the deep subsurface is necessary in order to understand the factors controlling the rate and extent of the microbially catalyzed redox reactions that influence the geophysical properties of these environments. Furthermore, there is an increasing threat that deep aquifers, an important drinking water resource, may be contaminated by man's activities, and there is a need to predict the extent to which microbial activity may remediate such contamination. Metabolically active microorganisms can be recovered from a diversity of deep subsurface environments. The available evidence suggests that these microorganisms are responsible for catalyzing the oxidation of organic matter coupled to a variety of electron acceptors just as microorganisms do in surface sediments, but at much slower rates. The technical difficulties in aseptically sampling deep subsurface sediments and the fact that microbial processes in laboratory incubations of deep subsurface material often do not mimic in situ processes frequently necessitate that microbial activity in the deep subsurface be inferred through nonmicrobiological analyses of ground water. These approaches include measurements of dissolved H2, which can predict the predominant microbially catalyzed redox reactions in aquifers, as well as geochemical and groundwater flow modeling, which can be used to estimate the rates of microbial processes. Microorganisms recovered from the deep subsurface have the potential to affect the fate of toxic organics and inorganic contaminants in groundwater. Microbial activity also greatly influences 1 the chemistry of many pristine groundwaters and contributes to such phenomena as porosity development in carbonate aquifers, accumulation of undesirably high concentrations of dissolved iron, and production of methane and hydrogen sulfide. Although the last decade has seen a dramatic increase in interest in deep subsurface microbiology, in comparison with the study of

Soil microbial activity in Aleppo pine stands naturally regenerated after fire: silvicultural management and induced drought

Directory of Open Access Journals (Sweden)

D. Moya

2013-01-01

Full Text Available In post-fire restoration, early monitoring is mandatory to check impacts and ecosystem responses to apply proper management according to social standards and ecological conditions. In areas where the natural regeneration was successful, excessive tree density can be found which induces to high intraspecific competence and assisted restoration management could be adequate. In addition, climatic changes will have large impacts on vegetation productivity and resilience since the regional models for south-eastern Spain predicts a rainfall decrease of about 20% and temperature increase of 4.5 ºC. The microbial biomass could be used as indicator of ecosystem recovery, since it is negatively affected by wildfires and depends on fire characteristics, vegetation and soil properties. Our aim is to determine how forest management may affect the ecosystem recovery in different climatic scenarios, included drought scenarios with and without forest management (thinning.We compared soil physicochemical properties and microbial activity in four scenarios: unmanaged and thinned stands in two rainfall scenarios (under induced drought. The study areas were set close to Yeste (Albacete where Aleppo pine forest were burned in summer 1994 (nearly 14000 ha. We set sixteen rectangular plots (150 m2; 15 m ×10 m implementing experimental silvicultural treatments: thinning eight plots in 2004, reducing the naturally recovered tree density from about 12000 to 1600 pine trees ha-1. In addition, in half the plots, we induced drought conditions from about 500 to 400 mm (20% from March 2009. In every plot, we monitored temperature at ground level (Ts, 10 cm depth (T10d and soil relative humidity (RH. Taking into account season of the year and canopy coverage, we collected soil samples in mid-winter (ending January 2011 and mid-spring (ending May 2011 under pine trees and in bare soil. The soil samples were used to evaluate soil physicochemical properties and soil microbial

Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard)

Science.gov (United States)

Kotas, Petr; Šantrůčková, Hana; Elster, Josef; Kaštovská, Eva

2018-03-01

The unique and fragile High Arctic ecosystems are vulnerable to global climate warming. The elucidation of factors driving microbial distribution and activity in arctic soils is essential for a comprehensive understanding of ecosystem functioning and its response to environmental change. The goals of this study were to investigate microbial biomass and activity, microbial community structure (MCS), and their environmental controls in soils along three elevational transects in the coastal mountains of Billefjorden, central Svalbard. Soils from four different altitudes (25, 275, 525 and 765 m above sea level) were analyzed for a suite of characteristics including temperature regimes, organic matter content, base cation availability, moisture, pH, potential respiration, and microbial biomass and community structure using phospholipid fatty acids (PLFAs). We observed significant spatial heterogeneity of edaphic properties among transects, resulting in transect-specific effects of altitude on most soil parameters. We did not observe any clear elevation pattern in microbial biomass, and microbial activity revealed contrasting elevational patterns between transects. We found relatively large horizontal variability in MCS (i.e., between sites of corresponding elevation in different transects), mainly due to differences in the composition of bacterial PLFAs, but also a systematic altitudinal shift in MCS related to different habitat preferences of fungi and bacteria, which resulted in high fungi-to-bacteria ratios at the most elevated sites. The biological soil crusts on these most elevated, unvegetated sites can host microbial assemblages of a size and activity comparable to those of the arctic tundra ecosystem. The key environmental factors determining horizontal and vertical changes in soil microbial properties were soil pH, organic carbon content, soil moisture and Mg2+ availability.

Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard

Directory of Open Access Journals (Sweden)

P. Kotas

2018-03-01

Full Text Available The unique and fragile High Arctic ecosystems are vulnerable to global climate warming. The elucidation of factors driving microbial distribution and activity in arctic soils is essential for a comprehensive understanding of ecosystem functioning and its response to environmental change. The goals of this study were to investigate microbial biomass and activity, microbial community structure (MCS, and their environmental controls in soils along three elevational transects in the coastal mountains of Billefjorden, central Svalbard. Soils from four different altitudes (25, 275, 525 and 765 m above sea level were analyzed for a suite of characteristics including temperature regimes, organic matter content, base cation availability, moisture, pH, potential respiration, and microbial biomass and community structure using phospholipid fatty acids (PLFAs. We observed significant spatial heterogeneity of edaphic properties among transects, resulting in transect-specific effects of altitude on most soil parameters. We did not observe any clear elevation pattern in microbial biomass, and microbial activity revealed contrasting elevational patterns between transects. We found relatively large horizontal variability in MCS (i.e., between sites of corresponding elevation in different transects, mainly due to differences in the composition of bacterial PLFAs, but also a systematic altitudinal shift in MCS related to different habitat preferences of fungi and bacteria, which resulted in high fungi-to-bacteria ratios at the most elevated sites. The biological soil crusts on these most elevated, unvegetated sites can host microbial assemblages of a size and activity comparable to those of the arctic tundra ecosystem. The key environmental factors determining horizontal and vertical changes in soil microbial properties were soil pH, organic carbon content, soil moisture and Mg2+ availability.

An integrated study to analyze soil microbial community structure and metabolic potential in two forest types.

Science.gov (United States)

Zhang, Yuguang; Cong, Jing; Lu, Hui; Yang, Caiyun; Yang, Yunfeng; Zhou, Jizhong; Li, Diqiang

2014-01-01

Soil microbial metabolic potential and ecosystem function have received little attention owing to difficulties in methodology. In this study, we selected natural mature forest and natural secondary forest and analyzed the soil microbial community and metabolic potential combing the high-throughput sequencing and GeoChip technologies. Phylogenetic analysis based on 16S rRNA sequencing showed that one known archaeal phylum and 15 known bacterial phyla as well as unclassified phylotypes were presented in these forest soils, and Acidobacteria, Protecobacteria, and Actinobacteria were three of most abundant phyla. The detected microbial functional gene groups were related to different biogeochemical processes, including carbon degradation, carbon fixation, methane metabolism, nitrogen cycling, phosphorus utilization, sulfur cycling, etc. The Shannon index for detected functional gene probes was significantly higher (PThe regression analysis showed that a strong positive (Pthe soil microbial functional gene diversity and phylogenetic diversity. Mantel test showed that soil oxidizable organic carbon, soil total nitrogen and cellulose, glucanase, and amylase activities were significantly linked (Pthe relative abundance of corresponded functional gene groups. Variance partitioning analysis showed that a total of 81.58% of the variation in community structure was explained by soil chemical factors, soil temperature, and plant diversity. Therefore, the positive link of soil microbial structure and composition to functional activity related to ecosystem functioning was existed, and the natural secondary forest soil may occur the high microbial metabolic potential. Although the results can't directly reflect the actual microbial populations and functional activities, this study provides insight into the potential activity of the microbial community and associated feedback responses of the terrestrial ecosystem to environmental changes.

Revisiting life strategy concepts in environmental microbial ecology.

Science.gov (United States)

Ho, Adrian; Di Lonardo, D Paolo; Bodelier, Paul L E

2017-03-01

Microorganisms are physiologically diverse, possessing disparate genomic features and mechanisms for adaptation (functional traits), which reflect on their associated life strategies and determine at least to some extent their prevalence and distribution in the environment. Unlike animals and plants, there is an unprecedented diversity and intractable metabolic versatility among bacteria, making classification or grouping these microorganisms based on their functional traits as has been done in animal and plant ecology challenging. Nevertheless, based on representative pure cultures, microbial traits distinguishing different life strategies had been proposed, and had been the focus of previous reviews. In the environment, however, the vast majority of naturally occurring microorganisms have yet to be isolated, restricting the association of life strategies to broad phylogenetic groups and/or physiological characteristics. Here, we reviewed the literature to determine how microbial life strategy concepts (i.e. copio- and oligotrophic strategists, and competitor-stress tolerator-ruderals framework) are applied in complex microbial communities. Because of the scarcity of direct empirical evidence elucidating the associated life strategies in complex communities, we rely heavily on observational studies determining the response of microorganisms to (a)biotic cues (e.g. resource availability) to infer microbial life strategies. Although our focus is on the life strategies of bacteria, parallels were drawn from the fungal community. Our literature search showed inconsistency in the community response of proposed copiotrophic- and oligotrophic-associated microorganisms (phyla level) to changing environmental conditions. This suggests that tracking microorganisms at finer phylogenetic and taxonomic resolution (e.g. family level or lower) may be more effective to capture changes in community response and/or that edaphic factors exert a stronger effect in community response

Location of Microbial Ecology Evaluation Device in Apollo Command Module

Science.gov (United States)

1971-01-01

The location of the Microbial Ecology Evaluation Device (MEED) installed on the open hatch of the Apollo Command Module is illustrated in this photograph. The MEED, equipment of the Microbial Response in Space Environment experiment, will house a selection of microbial systems. The MEED will be deployed during the extravehicular activity on the transearth coast phase of the Aopllo 16 lunar landing mission. The purpose of the experiment will be to measure the effects of certain space environmental parameters on the microbial test systems.

Canceling effect leads temperature insensitivity of hydrolytic enzymes in soil

Science.gov (United States)

Razavi, Bahar S.; Blagodatskaya, Evgenia; Kuzyakov, Yakov

2015-04-01

microorganisms in soil at these temperature ranges. We conclude that the temperature sensitivity (Q10) of enzyme activity declines at higher temperature and lower concentration of substrates in soil. Overall, our results suggest that the fine-scale (five degree) temperature resolution level needs to be considered in global earth system models especially at temperature thresholds for physiological groups of soil microorganisms. Refcences: Allison, S.D., Wallenstein, M.D., Bradford, M.A., 2010. Soil-carbon response to warming dependent on microbial physiology. Nat. Geosci. 3, 336-340. doi:10.1038/ngeo846 Chen, R., Blagodatskaya, E., Senbayram, M., Blagodatsky, S., Myachina, O., Dittert, K., Kuzyakov, Y., 2012. Decomposition of biogas residues in soil and their effects on microbial growth kinetics and enzyme activities. Biomass Bioenergy 45, 221-229. doi:10.1016/j.biombioe.2012.06.014 German, D.P., Weintraub, M.N., Grandy, A.S., Lauber, C.L., Rinkes, Z.L., Allison, S.D., 2011. Optimization of hydrolytic and oxidative enzyme methods for ecosystem studies. Soil Biol. Biochem. 43, 1387-1397. doi:10.1016/j.soilbio.2011.03.017

Microbial ecology and biogeochemistry of continental Antarctic soils

Directory of Open Access Journals (Sweden)

Don A Cowan

2014-04-01

Full Text Available The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbour microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths possess a genetic capacity for nitrogen and carbon cycling, polymer degradation and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

Roots affect the response of heterotrophic soil respiration to temperature in tussock grass microcosms.

Science.gov (United States)

Graham, Scott L; Millard, Peter; Hunt, John E; Rogers, Graeme N D; Whitehead, David

2012-07-01

While the temperature response of soil respiration (R(S)) has been well studied, the partitioning of heterotrophic respiration (R(H)) by soil microbes from autotrophic respiration (R(A)) by roots, known to have distinct temperature sensitivities, has been problematic. Further complexity stems from the presence of roots affecting R(H), the rhizosphere priming effect. In this study the short-term temperature responses of R(A) and R(H) in relation to rhizosphere priming are investigated. Temperature responses of R(A), R(H) and rhizosphere priming were assessed in microcosms of Poa cita using a natural abundance δ(13)C discrimination approach. The temperature response of R(S) was found to be regulated primarily by R(A), which accounted for 70 % of total soil respiration. Heterotrophic respiration was less sensitive to temperature in the presence of plant roots, resulting in negative priming effects with increasing temperature. The results emphasize the importance of roots in regulating the temperature response of R(S), and a framework is presented for further investigation into temperature effects on heterotrophic respiration and rhizosphere priming, which could be applied to other soil and vegetation types to improve models of soil carbon turnover.

Toward Understanding the Dynamics of Microbial Communities in an Estuarine System

KAUST Repository

Zhang, Weipeng; Bougouffa, Salim; Wang, Yong; Lee, On On; Yang, Jiangke; Chan, Colin; Song, Xingyu; Qian, Pei-Yuan

2014-01-01

Community assembly theories such as species sorting theory provide a framework for understanding the structures and dynamics of local communities. The effect of theoretical mechanisms can vary with the scales of observation and effects of specific environmental factors. Based on 16S rRNA gene tag pyrosequencing, different structures and temporal succession patterns were discovered between the surface sediments and bottom water microbial communities in the Pearl River Estuary (PRE). The microbial communities in the surface sediment samples were more diverse than those in the bottom water samples, and several genera were specific for the water or sediment communities. Moreover, water temperature was identified as the main variable driving community dynamics and the microbial communities in the sediment showed a greater temporal change. We speculate that nutrient-based species sorting and bacterial plasticity to the temperature contribute to the variations observed between sediment and water communities in the PRE. This study provides a more comprehensive understanding of the microbial community structures in a highly dynamic estuarine system and sheds light on the applicability of ecological theoretical mechanisms.

Toward understanding the dynamics of microbial communities in an estuarine system.

Directory of Open Access Journals (Sweden)

Weipeng Zhang

Full Text Available Community assembly theories such as species sorting theory provide a framework for understanding the structures and dynamics of local communities. The effect of theoretical mechanisms can vary with the scales of observation and effects of specific environmental factors. Based on 16S rRNA gene tag pyrosequencing, different structures and temporal succession patterns were discovered between the surface sediments and bottom water microbial communities in the Pearl River Estuary (PRE. The microbial communities in the surface sediment samples were more diverse than those in the bottom water samples, and several genera were specific for the water or sediment communities. Moreover, water temperature was identified as the main variable driving community dynamics and the microbial communities in the sediment showed a greater temporal change. We speculate that nutrient-based species sorting and bacterial plasticity to the temperature contribute to the variations observed between sediment and water communities in the PRE. This study provides a more comprehensive understanding of the microbial community structures in a highly dynamic estuarine system and sheds light on the applicability of ecological theoretical mechanisms.

Toward Understanding the Dynamics of Microbial Communities in an Estuarine System

KAUST Repository

Zhang, Weipeng

2014-04-14

Community assembly theories such as species sorting theory provide a framework for understanding the structures and dynamics of local communities. The effect of theoretical mechanisms can vary with the scales of observation and effects of specific environmental factors. Based on 16S rRNA gene tag pyrosequencing, different structures and temporal succession patterns were discovered between the surface sediments and bottom water microbial communities in the Pearl River Estuary (PRE). The microbial communities in the surface sediment samples were more diverse than those in the bottom water samples, and several genera were specific for the water or sediment communities. Moreover, water temperature was identified as the main variable driving community dynamics and the microbial communities in the sediment showed a greater temporal change. We speculate that nutrient-based species sorting and bacterial plasticity to the temperature contribute to the variations observed between sediment and water communities in the PRE. This study provides a more comprehensive understanding of the microbial community structures in a highly dynamic estuarine system and sheds light on the applicability of ecological theoretical mechanisms.

The Deep-Sea Microbial Community from the Amazonian Basin Associated with Oil Degradation.

Science.gov (United States)

Campeão, Mariana E; Reis, Luciana; Leomil, Luciana; de Oliveira, Louisi; Otsuki, Koko; Gardinali, Piero; Pelz, Oliver; Valle, Rogerio; Thompson, Fabiano L; Thompson, Cristiane C

2017-01-01

One consequence of oil production is the possibility of unplanned accidental oil spills; therefore, it is important to evaluate the potential of indigenous microorganisms (both prokaryotes and eukaryotes) from different oceanic basins to degrade oil. The aim of this study was to characterize the microbial response during the biodegradation process of Brazilian crude oil, both with and without the addition of the dispersant Corexit 9500, using deep-sea water samples from the Amazon equatorial margin basins, Foz do Amazonas and Barreirinhas, in the dark and at low temperatures (4°C). We collected deep-sea samples in the field (about 2570 m below the sea surface), transported the samples back to the laboratory under controlled environmental conditions (5°C in the dark) and subsequently performed two laboratory biodegradation experiments that used metagenomics supported by classical microbiological methods and chemical analysis to elucidate both taxonomic and functional microbial diversity. We also analyzed several physical-chemical and biological parameters related to oil biodegradation. The concomitant depletion of dissolved oxygen levels, oil droplet density characteristic to oil biodegradation, and BTEX concentration with an increase in microbial counts revealed that oil can be degraded by the autochthonous deep-sea microbial communities. Indigenous bacteria (e.g., Alteromonadaceae, Colwelliaceae , and Alcanivoracaceae ), archaea (e.g., Halobacteriaceae, Desulfurococcaceae , and Methanobacteriaceae ), and eukaryotic microbes (e.g., Microsporidia, Ascomycota, and Basidiomycota) from the Amazonian margin deep-sea water were involved in biodegradation of Brazilian crude oil within less than 48-days in both treatments, with and without dispersant, possibly transforming oil into microbial biomass that may fuel the marine food web.

The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

Energy Technology Data Exchange (ETDEWEB)

Adelaja, Oluwaseun, E-mail: o.adelaja@my.westminster.ac.uk; Keshavarz, Tajalli, E-mail: t.keshavarz@westminster.ac.uk; Kyazze, Godfrey, E-mail: g.kyazze@westminster.ac.uk

2015-02-11

Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m{sup 2} maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m{sup 2}, 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents.

The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

International Nuclear Information System (INIS)

Adelaja, Oluwaseun; Keshavarz, Tajalli; Kyazze, Godfrey

2015-01-01

Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m 2 maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m 2 , 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents

Geochemical and physical drivers of microbial community structure in hot spring ecosystems

Science.gov (United States)

Havig, J. R.; Hamilton, T. L.; Boyd, E. S.; Meyer-Dombard, D. R.; Shock, E.

2012-12-01

Microbial communities in natural systems are typically characterized using samples collected from a single time point, thereby neglecting the temporal dynamics that characterize natural systems. The composition of these communities obtained from single point samples is then related to the geochemistry and physical parameters of the environment. Since most microbial life is adapted to a relatively narrow ecological niche (multiplicity of physical and chemical parameters that characterize a local habitat), these assessments provide only modest insight into the controls on community composition. Temporal variation in temperature or geochemical composition would be expected to add another dimension to the complexity of niche space available to support microbial diversity, with systems that experience greater variation supporting a greater biodiversity until a point where the variability is too extreme. . Hot springs often exhibit significant temporal variation, both in physical as well as chemical characteristics. This is a result of subsurface processes including boiling, phase separation, and differential mixing of liquid and vapor phase constituents. These characteristics of geothermal systems, which vary significantly over short periods of time, provide ideal natural laboratories for investigating how i) the extent of microbial community biodiversity and ii) the composition of those communities are shaped by temporal fluctuations in geochemistry. Geochemical and molecular samples were collected from 17 temporally variable hot springs across Yellowstone National Park, Wyoming. Temperature measurements using data-logging thermocouples, allowing accurate determination of temperature maximums, minimums, and ranges for each collection site, were collected in parallel, along with multiple geochemical characterizations as conditions varied. There were significant variations in temperature maxima (54.5 to 90.5°C), minima (12.5 to 82.5°C), and range (3.5 to 77.5°C) for

Effects of post-processing handling and packaging on microbial populations

International Nuclear Information System (INIS)

Zagory, D.

1999-01-01

The type of produce, process conditions, and prior temperature management will all affect the mix of microorganisms found on fresh produce. Normally, fresh produce will be covered by a complex mix of bacteria, fungi and yeasts that are characteristic of that fruit or vegetable. For example, carrots typically have large numbers of Lactobacillus and other lactic acid bacteria while apples may have relatively large numbers of yeasts. Which of these microorganisms will come to dominate the population will be a function of the make-up of the original population on the product in the field, distribution time, distribution temperature and the atmosphere within the package. Another chief determinant of microbial populations will be the physiological condition of the product. Factors that injure or weaken the plant tissues may be expected to encourage microbial growth while conditions that maintain the physiological integrity of the tissues may be expected to discourage microbial growth. Each of these factors can be expected to affect the make-up of the microbial population in characteristic ways but always constrained by the initial condition of original population makeup. This paper describes which microorganisms are favored by given conditions in order to develop a concept of microbial management designed to favor desirable microbes at the expense of undesirable ones. Particular emphasis will be placed on the effects of modified atmospheres on microorganisms, especially human pathogens

Microbial ecology of deep-sea hypersaline anoxic basins

KAUST Repository

Merlino, Giuseppe; Barozzi, Alan; Michoud, Gregoire; Ngugi, David; Daffonchio, Daniele

2018-01-01

of mixing and by extreme conditions of salinity, anoxia, and relatively high hydrostatic pressure and temperatures. Due to these combined selection factors, unique microbial assemblages thrive in these polyextreme ecosystems. The topological localization

Role of EPS, Dispersant and Nutrients on the Microbial Response and MOS Formation in the Subarctic Northeast Atlantic

Directory of Open Access Journals (Sweden)

Tony Gutierrez

2017-04-01

Full Text Available In this study we report the formation of marine oil snow (MOS, its associated microbial community, the factors influencing its formation, and the microbial response to crude oil in surface waters of the Faroe-Shetland Channel (FSC. The FSC is a subarctic region that is hydrodynamically complex located in the northeast Atlantic where oil extraction is currently occurring and where exploration is likely to expand into its deeper waters (>500 m. A major oil spill in this region may mirror the aftermath that ensued following the Deepwater Horizon (DWH blowout in the Gulf of Mexico, where the massive influx of Macondo crude oil triggered the formation of copious quantities of rapidly sinking MOS and successional blooms of opportunistic oil-degrading bacteria. In laboratory experiments, we simulated environmental conditions in sea surface waters of the FSC using water collected from this site during the winter of 2015. We demonstrated that the presence of dispersant triggers the formation of MOS, and that nutrient amendments magnify this. Illumina MiSeq sequencing revealed the enrichment on MOS of associated oil-degrading (Cycloclasticus, Thalassolituus, Marinobacter and EPS-producing (Halomonas, Pseudoalteromonas, Alteromonas bacteria, and included major representation by Psychrobacter and Cobetia with putative oil-degrading/EPS-producing qualities. The formation of marine snow, in the absence of crude oil and dispersant, in seawater amended with nutrients alone indicated that the de novo synthesis of bacterial EPS is a key factor in MOS formation, and the glycoprotein composition of the MOS aggregates confirmed that its amorphous biopolymeric matrix was of microbial (likely bacterial origin. The presence of dispersants and crude oil with/without nutrients resulted in distinct microbial responses marked by intermittent, and in some cases short-lived, blooms of opportunistic heterotrophs, principally obligate hydrocarbonoclastic (Alcanivorax

European temperature responses to blocking and ridge regional patterns

Science.gov (United States)

Sousa, Pedro M.; Trigo, Ricardo M.; Barriopedro, David; Soares, Pedro M. M.; Santos, João A.

2018-01-01

Blocking occurrence and its impacts on European temperature have been studied in the last decade. However, most previous studies on blocking impacts have focused on winter only, disregarding its fingerprint in summer and differences with other synoptic patterns that also trigger temperature extremes. In this work, we provide a clear distinction between high-latitude blocking and sub-tropical ridges occurring in three sectors of the Euro-Atlantic region, describing their climatology and consequent impacts on European temperature during both winter and summer. Winter blocks (ridges) are generally associated to colder (warmer) than average conditions over large regions of Europe, in some areas with anomalies larger than 5 °C, particularly for the patterns occurring in the Atlantic and Central European sectors. During summer, there is a more regional response characterized by above average temperature for both blocking and ridge patterns, especially those occurring in continental areas, although negative temperature anomalies persist in southernmost areas during blocking. An objective analysis of the different forcing mechanisms associated to each considered weather regime has been performed, quantifying the importance of the following processes in causing the temperature anomalies: horizontal advection, vertical advection and diabatic heating. While during winter advection processes tend to be more relevant to explain temperature responses, in summer radiative heating under enhanced insolation plays a crucial role for both blocking and ridges. Finally, the changes in the distributions of seasonal temperature and in the frequencies of extreme temperature indices were also examined for specific areas of Europe. Winter blocking and ridge patterns are key drivers in the occurrence of regional cold and warm extreme temperatures, respectively. In summer, they are associated with substantial changes in the frequency of extremely warm days, but with different signatures in

Microbial decomposers not constrained by climate history along a Mediterranean climate gradient in southern California.

Science.gov (United States)

Baker, Nameer R; Khalili, Banafshe; Martiny, Jennifer B H; Allison, Steven D

2018-06-01

Microbial decomposers mediate the return of CO 2 to the atmosphere by producing extracellular enzymes to degrade complex plant polymers, making plant carbon available for metabolism. Determining if and how these decomposer communities are constrained in their ability to degrade plant litter is necessary for predicting how carbon cycling will be affected by future climate change. We analyzed mass loss, litter chemistry, microbial biomass, extracellular enzyme activities, and enzyme temperature sensitivities in grassland litter transplanted along a Mediterranean climate gradient in southern California. Microbial community composition was manipulated by caging litter within bags made of nylon membrane that prevent microbial immigration. To test whether grassland microbes were constrained by climate history, half of the bags were inoculated with local microbial communities native to each gradient site. We determined that temperature and precipitation likely interact to limit microbial decomposition in the extreme sites along our gradient. Despite their unique climate history, grassland microbial communities were not restricted in their ability to decompose litter under different climate conditions across the gradient, although microbial communities across our gradient may be restricted in their ability to degrade different types of litter. We did find some evidence that local microbial communities were optimized based on climate, but local microbial taxa that proliferated after inoculation into litterbags did not enhance litter decomposition. Our results suggest that microbial community composition does not constrain C-cycling rates under climate change in our system, but optimization to particular resource environments may act as more general constraints on microbial communities. © 2018 by the Ecological Society of America.

Co-chaperone p23 regulates C. elegans Lifespan in Response to Temperature.

Directory of Open Access Journals (Sweden)

Makoto Horikawa

2015-04-01

Full Text Available Temperature potently modulates various physiologic processes including organismal motility, growth rate, reproduction, and ageing. In ectotherms, longevity varies inversely with temperature, with animals living shorter at higher temperatures. Thermal effects on lifespan and other processes are ascribed to passive changes in metabolic rate, but recent evidence also suggests a regulated process. Here, we demonstrate that in response to temperature, daf-41/ZC395.10, the C. elegans homolog of p23 co-chaperone/prostaglandin E synthase-3, governs entry into the long-lived dauer diapause and regulates adult lifespan. daf-41 deletion triggers constitutive entry into the dauer diapause at elevated temperature dependent on neurosensory machinery (daf-10/IFT122, insulin/IGF-1 signaling (daf-16/FOXO, and steroidal signaling (daf-12/FXR. Surprisingly, daf-41 mutation alters the longevity response to temperature, living longer than wild-type at 25°C but shorter than wild-type at 15°C. Longevity phenotypes at 25°C work through daf-16/FOXO and heat shock factor hsf-1, while short lived phenotypes converge on daf-16/FOXO and depend on the daf-12/FXR steroid receptor. Correlatively daf-41 affected expression of DAF-16 and HSF-1 target genes at high temperature, and nuclear extracts from daf-41 animals showed increased occupancy of the heat shock response element. Our studies suggest that daf-41/p23 modulates key transcriptional changes in longevity pathways in response to temperature.

Analytical solution of transient temperature in continuous wave end-pumped laser slab: Reduction of temperature distribution and time of thermal response

Directory of Open Access Journals (Sweden)

Shibib Khalid S.

2017-01-01

Full Text Available An analytical solution of transient 3-D heat equation based on integral transform method is derived. The result are compared with numerical solution, and good agreements are obtained. Minimization of response time and temperature distribution through a laser slab are tested. It is found that the increasing in the lateral convection heat transfer coefficient can significantly reduce the response time and the temperature distribution while no effect on response time is observed when changing pumping profile from Gaussian to top hat beam in spite of the latter reduce the temperature distribution, also it is found that dividing the pumping power between two slab ends might reduce the temperature distribution and it has no effect on thermal response time.

Response and resilience of soil microbial communities inhabiting in edible oil stress/contamination from industrial estates.

Science.gov (United States)

Patel, Vrutika; Sharma, Anukriti; Lal, Rup; Al-Dhabi, Naif Abdullah; Madamwar, Datta

2016-03-22

Gauging the microbial community structures and functions become imperative to understand the ecological processes. To understand the impact of long-term oil contamination on microbial community structure soil samples were taken from oil fields located in different industrial regions across Kadi, near Ahmedabad, India. Soil collected was hence used for metagenomic DNA extraction to study the capabilities of intrinsic microbial community in tolerating the oil perturbation. Taxonomic profiling was carried out by two different complementary approaches i.e. 16S rDNA and lowest common ancestor. The community profiling revealed the enrichment of phylum "Proteobacteria" and genus "Chromobacterium," respectively for polluted soil sample. Our results indicated that soil microbial diversity (Shannon diversity index) decreased significantly with contamination. Further, assignment of obtained metagenome reads to Clusters of Orthologous Groups (COG) of protein and Kyoto Encyclopedia of Genes and Genomes (KEGG) hits revealed metabolic potential of indigenous microbial community. Enzymes were mapped on fatty acid biosynthesis pathway to elucidate their roles in possible catalytic reactions. To the best of our knowledge this is first study for influence of edible oil on soil microbial communities via shotgun sequencing. The results indicated that long-term oil contamination significantly affects soil microbial community structure by acting as an environmental filter to decrease the regional differences distinguishing soil microbial communities.

In situ response time measurements of RTD temperature sensors

International Nuclear Information System (INIS)

Goncalves, I.M.P.

1985-01-01

The loop-current-step-response test provides a mean for determining the time constant of resistence thermometers. The test consist in heating the sensor a few degrees above ambient temperature by causing a step pertubation in the electric current that flows through the sensor leads. The developed mathematical transformation permits to use data collected during the internal heating transient to predict the sensor response to perturbations in fluid temperature. Experimental data obtained show that the time constant determined by method is within 15 percent of true value. The loop-current-step-response test is a remote in situ test, which can be performed with the sensor installed in the process. Consequently it takes account the local heat transfer conditions, and appropriated for nuclear power plants, where sensors are installed in points of difficult access. (author) [pt

Microbial community functional structure in response to antibiotics in pharmaceutical wastewater treatment systems.

Science.gov (United States)

Zhang, Yu; Xie, Jianping; Liu, Miaomiao; Tian, Zhe; He, Zhili; van Nostrand, Joy D; Ren, Liren; Zhou, Jizhong; Yang, Min

2013-10-15

It is widely demonstrated that antibiotics in the environment affect microbial community structure. However, direct evidence regarding the impacts of antibiotics on microbial functional structures in wastewater treatment systems is limited. Herein, a high-throughput functional gene array (GeoChip 3.0) in combination with quantitative PCR and clone libraries were used to evaluate the microbial functional structures in two biological wastewater treatment systems, which treat antibiotic production wastewater mainly containing oxytetracycline. Despite the bacteriostatic effects of antibiotics, the GeoChip detected almost all key functional gene categories, including carbon cycling, nitrogen cycling, etc., suggesting that these microbial communities were functionally diverse. Totally 749 carbon-degrading genes belonging to 40 groups (24 from bacteria and 16 from fungi) were detected. The abundance of several fungal carbon-degrading genes (e.g., glyoxal oxidase (glx), lignin peroxidase or ligninase (lip), manganese peroxidase (mnp), endochitinase, exoglucanase_genes) was significantly correlated with antibiotic concentrations (Mantel test; P functional genes have been enhanced by the presence of antibiotics. However, from the fact that the majority of carbon-degrading genes were derived from bacteria and diverse antibiotic resistance genes were detected in bacteria, it was assumed that many bacteria could survive in the environment by acquiring antibiotic resistance and may have maintained the position as a main player in nutrient removal. Variance partitioning analysis showed that antibiotics could explain 24.4% of variations in microbial functional structure of the treatment systems. This study provides insights into the impacts of antibiotics on microbial functional structure of a unique system receiving antibiotic production wastewater, and reveals the potential importance of the cooperation between fungi and bacteria with antibiotic resistance in maintaining the

Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of methanogenesis in production water of high-temperature oil reservoirs amended with bicarbonate

Directory of Open Access Journals (Sweden)

Guang-Chao eYang

2016-03-01

Full Text Available CO2 sequestration in deep-subsurface formations including oil reservoirs is a potential measure to reduce the CO2 concentration in the atmosphere. However, the fate of the CO2 and the ecological influences in Carbon Dioxide Capture and Storage (CDCS facilities is not understood clearly. In the current study, the fate of CO2 (in bicarbonate form (0~90 mM with 10 mM of formate as electron donor and carbon source was investigated with high-temperature production water from oilfield in China. The isotope data showed that bicarbonate could be reduced to methane by methanogens and major pathway of methanogenesis could be syntrophic formate oxidation coupled with CO2 reduction and formate methanogenesis under the anaerobic conditions. The bicarbonate addition induced the shift of microbial community. Addition of bicarbonate and formate was associated with a decrease of Methanosarcinales, but promotion of Methanobacteriales in all treatments. Thermodesulfovibrio was the major group in all the samples and Thermacetogenium dominated in the high bicarbonate treatments. The results indicated that CO2 from CDCS could be transformed to methane and the possibility of microbial CO2 conversion for enhanced microbial energy recovery in oil reservoirs.

Mechanistic links between gut microbial community dynamics, microbial functions and metabolic health

Science.gov (United States)

Ha, Connie WY; Lam, Yan Y; Holmes, Andrew J

2014-01-01

Gut microbes comprise a high density, biologically active community that lies at the interface of an animal with its nutritional environment. Consequently their activity profoundly influences many aspects of the physiology and metabolism of the host animal. A range of microbial structural components and metabolites directly interact with host intestinal cells and tissues to influence nutrient uptake and epithelial health. Endocrine, neuronal and lymphoid cells in the gut also integrate signals from these microbial factors to influence systemic responses. Dysregulation of these host-microbe interactions is now recognised as a major risk factor in the development of metabolic dysfunction. This is a two-way process and understanding the factors that tip host-microbiome homeostasis over to dysbiosis requires greater appreciation of the host feedbacks that contribute to regulation of microbial community composition. To date, numerous studies have employed taxonomic profiling approaches to explore the links between microbial composition and host outcomes (especially obesity and its comorbidities), but inconsistent host-microbe associations have been reported. Available data indicates multiple factors have contributed to discrepancies between studies. These include the high level of functional redundancy in host-microbiome interactions combined with individual variation in microbiome composition; differences in study design, diet composition and host system between studies; and inherent limitations to the resolution of rRNA-based community profiling. Accounting for these factors allows for recognition of the common microbial and host factors driving community composition and development of dysbiosis on high fat diets. New therapeutic intervention options are now emerging. PMID:25469018

Response of microbial communities to pesticide residues in soil restored with Azolla imbricata.

Science.gov (United States)

Lu, Xiao-Ming; Lu, Peng-Zhen

2018-01-01

Under conditions of Azolla imbricata restoration, the high-throughput sequencing technology was employed to determine change trends of microbial community structures in the soil that had undergone long-term application of pesticides. The relationship between the content of pesticide residues in the soil and the microbial community structure was analyzed. The results indicated that the microbial diversity was strongly negatively correlated with the contents of pesticide residues in the soil. At a suitable dosage of 5 kg fresh A. imbricata per square meter of soil area, the soil microbial diversity increased by 12.0%, and the contents of pesticide residues decreased by 26.8-72.1%. Sphingobacterium, Sphingopyxis, Thermincola, Sphingobium, Acaryochloris, Megasphaera, Ralstonia, Pseudobutyrivibrio, Desulfitobacterium, Nostoc, Oscillochloris, and Aciditerrimonas may play major roles in the degradation of pesticide residues. Thauera, Levilinea, Geothrix, Thiobacillus, Thioalkalispira, Desulfobulbus, Polycyclovorans, Fluviicola, Deferrisoma, Erysipelothrix, Desulfovibrio, Cytophaga, Vogesella, Zoogloea, Azovibrio, Halomonas, Paludibacter, Crocinitomix, Haliscomenobacter, Hirschia, Silanimonas, Alkalibacter, Woodsholea, Peredibacter, Leptolinea, Chitinivorax, Candidatus_Lumbricincola, Anaerovorax, Propionivibrio, Parasegetibacter, Byssovorax, Runella, Leptospira, and Nitrosomonas may be indicators to evaluate the contents of pesticide residues.

Dielectric response of capacitor structures based on PZT annealed at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Kamenshchikov, Mikhail V., E-mail: Mikhailkamenshchikov@yandex.ru [Tver State University, 170002, Tver (Russian Federation); Solnyshkin, Alexander V. [Tver State University, 170002, Tver (Russian Federation); Pronin, Igor P. [Ioffe Institute, 194021, St. Petersburg (Russian Federation)

2016-12-09

Highlights: • Correlation of the microstructure of PZT films and dielectric response was found. • Difference of dielectric responses under low and high bias is caused by domains. • Internal fields is discussed on the basis of the space charges. • Dependences of PZT films characteristics on synthesis temperature are extremal. - Abstract: Dielectric response of thin-film capacitor structures of Pt/PZT/Pt deposited by the RF magnetron sputtering method and annealed at temperatures of 540–570 °C was investigated. It was found that dielectric properties of these structures depend on the synthesis temperature. Stability of a polarized state is considered on the basis of the analysis of hysteresis loops and capacitance–voltage (C–V) characteristics. The contribution of the domain mechanism in the dielectric response of the capacitor structure comprising a ferroelectric is discussed. Extreme dependences of electrophysical characteristics of PZT films on their synthesis temperature were observed. Correlation of dielectric properties with microstructure of these films is found out.

Diversity and distribution of autotrophic microbial community along environmental gradients in grassland soils on the Tibetan Plateau.

Science.gov (United States)

Guo, Guangxia; Kong, Weidong; Liu, Jinbo; Zhao, Jingxue; Du, Haodong; Zhang, Xianzhou; Xia, Pinhua

2015-10-01

Soil microbial autotrophs play a significant role in CO2 fixation in terrestrial ecosystem, particularly in vegetation-constrained ecosystems with environmental stresses, such as the Tibetan Plateau characterized by low temperature and high UV. However, soil microbial autotrophic communities and their driving factors remain less appreciated. We investigated the structure and shift of microbial autotrophic communities and their driving factors along an elevation gradient (4400-5100 m above sea level) in alpine grassland soils on the Tibetan Plateau. The autotrophic microbial communities were characterized by quantitative PCR, terminal restriction fragment length polymorphism (T-RFLP), and cloning/sequencing of cbbL genes, encoding the large subunit for the CO2 fixation protein ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). High cbbL gene abundance and high RubisCO enzyme activity were observed and both significantly increased with increasing elevations. Path analysis identified that soil RubisCO enzyme causally originated from microbial autotrophs, and its activity was indirectly driven by soil water content, temperature, and NH4 (+) content. Soil autotrophic microbial community structure dramatically shifted along the elevation and was jointly driven by soil temperature, water content, nutrients, and plant types. The autotrophic microbial communities were dominated by bacterial autotrophs, which were affiliated with Rhizobiales, Burkholderiales, and Actinomycetales. These autotrophs have been well documented to degrade organic matters; thus, metabolic versatility could be a key strategy for microbial autotrophs to survive in the harsh environments. Our results demonstrated high abundance of microbial autotrophs and high CO2 fixation potential in alpine grassland soils and provided a novel model to identify dominant drivers of soil microbial communities and their ecological functions.

Microbial Life in an Underground Gas Storage Reservoir

Science.gov (United States)

Bombach, Petra; van Almsick, Tobias; Richnow, Hans H.; Zenner, Matthias; Krüger, Martin

2015-04-01

While underground gas storage is technically well established for decades, the presence and activity of microorganisms in underground gas reservoirs have still hardly been explored today. Microbial life in underground gas reservoirs is controlled by moderate to high temperatures, elevated pressures, the availability of essential inorganic nutrients, and the availability of appropriate chemical energy sources. Microbial activity may affect the geochemical conditions and the gas composition in an underground reservoir by selective removal of anorganic and organic components from the stored gas and the formation water as well as by generation of metabolic products. From an economic point of view, microbial activities can lead to a loss of stored gas accompanied by a pressure decline in the reservoir, damage of technical equipment by biocorrosion, clogging processes through precipitates and biomass accumulation, and reservoir souring due to a deterioration of the gas quality. We present here results from molecular and cultivation-based methods to characterize microbial communities inhabiting a porous rock gas storage reservoir located in Southern Germany. Four reservoir water samples were obtained from three different geological horizons characterized by an ambient reservoir temperature of about 45 °C and an ambient reservoir pressure of about 92 bar at the time of sampling. A complementary water sample was taken at a water production well completed in a respective horizon but located outside the gas storage reservoir. Microbial community analysis by Illumina Sequencing of bacterial and archaeal 16S rRNA genes indicated the presence of phylogenetically diverse microbial communities of high compositional heterogeneity. In three out of four samples originating from the reservoir, the majority of bacterial sequences affiliated with members of the genera Eubacterium, Acetobacterium and Sporobacterium within Clostridiales, known for their fermenting capabilities. In

Molecular Analysis of Endolithic Microbial Communities in Volcanic Glasses

Science.gov (United States)

di Meo, C. A.; Giovannoni, S.; Fisk, M.

2002-12-01

Terrestrial and marine volcanic glasses become mineralogically and chemically altered, and in many cases this alteration has been attributed to microbial activity. We have used molecular techniques to study the resident microbial communities from three different volcanic environments that may be responsible for this crustal alteration. Total microbial DNA was extracted from rhyolite glass of the 7 million year old Rattlesnake Tuff in eastern Oregon. The DNA was amplified using the polymerase chain reaction (PCR) with bacterial primers targeting the 16S rRNA gene. This 16S rDNA was cloned and screened with restriction fragment length polymorphism (RFLP). Out of 89 total clones screened, 46 belonged to 13 different clone families containing two or more members, while 43 clones were unique. Sequences of eight clones representing the most dominant clone families in the library were 92 to 97% similar to soil bacterial species. In a separate study, young pillow basalts (rock- and seawater-associated archaea. The six rock community profiles were quite similar to each other, and the background water communities were also similar, respectively. Both the rock and water communities shared the same dominant peak. To identify the T-RFLP peaks corresponding to the individual members of the rock and seawater communities, clone libraries of the archaeal 16S rDNA for one basalt sample (Dive 3718) and its corresponding background water sample were constructed. The most abundant archaeal genes were closely related to uncultured Group I marine Crenarchaeota that have been previously identified from similar deep-sea habitats. These archaeal genes collectively correspond to the dominant T-RFLP peak present in both the rock and water samples. In a third study, we investigated the microbial community residing in a Hawaiian Scientific Drilling Program core collected near Hilo, Hawaii. Total microbial DNA was extracted from a depth of 1351 m in the drill core (ambient temperature in the

Microbial Detoxification of Bifenthrin by a Novel Yeast and Its Potential for Contaminated Soils Treatment

OpenAIRE

Chen, Shaohua; Luo, Jianjun; Hu, Meiying; Geng, Peng; Zhang, Yanbo

2012-01-01

Bifenthrin is one the most widespread pollutants and has caused potential effect on aquatic life and human health, yet little is known about microbial degradation in contaminated regions. A novel yeast strain ZS-02, isolated from activated sludge and identified as Candida pelliculosa based on morphology, API test and 18S rDNA gene analysis, was found highly effective in degrading bifenthrin over a wide range of temperatures (20-40 °C) and pH (5-9). On the basis of response surface methodology...

Seismic Responses of a Cable-Stayed Bridge with Consideration of Uniform Temperature Load

Directory of Open Access Journals (Sweden)

Junjun Guo

2016-12-01

Full Text Available The effects of temperature load on the dynamic responses of cable-stayed bridges have attracted the attention of researchers in recent years. However, these investigations mainly focus on the influence of temperature on the dynamic characteristics of structures, such as vibration mode and frequency. This paper discusses the effects of uniform temperature changes on the seismic responses of a cable-stayed bridge. A three dimensional finite element model of a cable-stayed bridge using OpenSees is established for nonlinear time history analysis, and uniform temperature load is applied to the prototype bridge before the conducting of seismic excitation. Three ground motion records are selected from the PEER strong motion database based on the design spectrum. Case studies are then performed considering the varying temperature and the connections between the deck and pylons of the bridge. The result shows that the seismic responses of the bridge are significantly increased with the consideration of temperature load. Meanwhile, the types between the deck and pylon also have notable impacts on the seismic responses of the bridge with and without temperature changes. This research could provide a reference for designers during the design phase of cable-stayed brides.

Resistance temperature sensor aging degradation identification using LCSR (Loop Current Step Response) test

International Nuclear Information System (INIS)

Santos, Roberto Carlos dos; Goncalves, Iraci Martine Pereira

2013-01-01

Most critical process temperatures in nuclear power plants are measured using RTD (Resistance Temperature Detector) and thermocouples. In a PWR (Pressure Water Reactor) plant, the primary coolant temperature and feedwater temperature are measured using RTDs, and the temperature of the water that exits the reactor core is measured using thermocouples. These thermocouples are mainly used for temperature monitoring purposes and are therefore not generally subject to very stringent requirements for accuracy and response-time performance. In contrast, primary coolant RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs and thermocouples has been characterized by a single parameter called the Plunge Time Constant. This is defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature is impressed on its surface. This step change is typically achieved by suddenly immersing the sensor in a rotating tank of water, called Plunge Test. In nuclear reactors, however, plunge testing is inconvenient because the sensor must be removed from the reactor coolant piping and taken to a laboratory for testing. Nuclear reactor service conditions of 150 bar and 300°C are difficult to reproduce in the laboratory. Therefore, all laboratory tests are performed at much milder conditions, and the results are extrapolated to service conditions. This leads to significant errors in the measurement of sensor response times and an insitu test method called LCSR - Loop Current Step Response test was developed in the mid-1970s to measure remotely the response time of RTDs. In the LCSR method, the sensing element is heated by an electric current; the current causes Joule heating in the sensor and results in a temperature transient inside the sensor. The temperature transient in the element is recorded, and from this transient, the

Investigating Microbial Habitats in Hydrothermal Chimneys using Ti-Thermocouple Arrays: Microbial Diversity

Science.gov (United States)

Pagé, A.; Tivey, M. K.; Stakes, D. S.; Bradley, A. M.; Seewald, J. S.; Wheat, C. G.; Reysenbach, A.

2004-12-01

In order to examine the changes that occur in the microbial community composition as a deep-sea hydrothermal vent chimney develops, we deployed Ti-thermocouple arrays over high temperature vents at two active sites of the Guaymas Basin Southern Trough. Chimney material that precipitated around the arrays was recovered after 4 and 72 days. Chimney material that precipitated prior to deployment of the arrays was also recovered at one of the sites (Busted Shroom). Culture-independent analysis based on the small subunit rRNA sequence (cloning and DGGE) was used to determine the microbial diversity associated with subsamples of each chimney. The original Busted Shroom chimney (BSO) was dominated by members of the Crenarchaeota Marine Group I, a group of cosmopolitan marine Archaea, ɛ -Proteobacteria, and γ -Proteobacteria, two divisions of Bacteria that are common to deep-sea vents. The 4 days old Busted Shroom chimney (BSD1) was dominated by members of the Methanocaldococcaceae, hyperthermophilic methanogens, and the 72 days old chimney (BSD2) by members of the Methanosarcinaceae, mesophilic and thermophilic methanogens. At the second site, Toadstool, the 72 days old chimney material that had precipitated around the array (TS) revealed the dominance of sequences from uncultured marine Archaea, the DHVE group I and II, and from the ɛ -Proteobacteria. Additionally, sequences belonging to the Methanocaldococcaceae and Desulfurococcaceae were recovered next to thermocouples that were at temperatures of 109° C (at Busted Shroom) and 116° C (at Toadstool), respectively. These temperatures are higher than the upper limit for growth of cultured representatives from each family.

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

Science.gov (United States)

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

2014-05-01

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

North American International Society for Microbial Electrochemical Technologies Meeting (Abstracts)

Science.gov (United States)

2016-04-18

electrode interface in Shewanella oneidensis MR-1 Catarina Paquete1, Bruno Fonseca1, Ricardo O. Louro1 1 Instituto de Tecnologia Química e Biológica...response to anodic pH variation in a dual chamber microbial fuel cell Valentina Margaria, Instituto Italiano di Tecnologia , Italy 2-15 Microbial...SnO2 nanostructured composite for cathode oxygen reduction reaction in microbial fuel cells Adriano Sacco, Instituto Italiano di Tecnologia , Italy 2

Metagenomic analysis of permafrost microbial community response to thaw

Energy Technology Data Exchange (ETDEWEB)

Mackelprang, R.; Waldrop, M.P.; DeAngelis, K.M.; David, M.M.; Chavarria, K.L.; Blazewicz, S.J.; Rubin, E.M.; Jansson, J.K.

2011-07-01

We employed deep metagenomic sequencing to determine the impact of thaw on microbial phylogenetic and functional genes and related this data to measurements of methane emissions. Metagenomics, the direct sequencing of DNA from the environment, allows for the examination of whole biochemical pathways and associated processes, as opposed to individual pieces of the metabolic puzzle. Our metagenome analyses revealed that during transition from a frozen to a thawed state there were rapid shifts in many microbial, phylogenetic and functional gene abundances and pathways. After one week of incubation at 5°C, permafrost metagenomes converged to be more similar to each other than while they were frozen. We found that multiple genes involved in cycling of C and nitrogen shifted rapidly during thaw. We also constructed the first draft genome from a complex soil metagenome, which corresponded to a novel methanogen. Methane previously accumulated in permafrost was released during thaw and subsequently consumed by methanotrophic bacteria. Together these data point towards the importance of rapid cycling of methane and nitrogen in thawing permafrost.

Temperature sensitivity differences with depth and season between carbon, nitrogen, and phosphorus cycling enzyme activities in an ombrotrophic peatland system

Science.gov (United States)

Steinweg, J. M.; Kostka, J. E.; Hanson, P. J.; Schadt, C. W.

2017-12-01

Northern peatlands have large amounts of soil organic matter due to reduced decomposition. Breakdown of organic matter is initially mediated by extracellular enzymes, the activity of which may be controlled by temperature, moisture, and substrate availability, all of which vary seasonally throughout the year and with depth. In typical soils the majority of the microbial biomass and decomposition occurs within the top 30cm due to reduced organic matter inputs in the subsurface however peatlands by their very nature contain large amounts of organic matter throughout their depth profile. We hypothesized that potential enzyme activity would be greatest at the surface of the peat due to a larger microbial biomass compared to 40cm and 175cm below the surface and that temperature sensitivity would be greatest at the surface during winter but lowest during the summer due to high temperatures and enzyme efficiency. Peat samples were collected in February, July, and August 2012 from the DOE Spruce and Peatland Responses Under Climatic and Environmental Change project at Marcell Experimental Forest S1 bog. We measured potential activity of hydrolytic enzymes involved in three different nutrient cycles: beta-glucosidase (carbon), leucine amino peptidase (nitrogen), and phosphatase (phosphorus) at 15 temperature points ranging from 3°C to 65°C. Enzyme activity decreased with depth as expected but there was no concurrent change in activation energy (Ea). The reduction in enzyme activity with depth indicates a smaller pool which coincided with a decreased microbial biomass. Differences in enzyme activity with depth also mirrored the changes in peat composition from the acrotelm to the catotelm. Season did play a role in temperature sensitivity with Ea of β-glucosidase and phosphatase being the lowest in August as expected but leucine amino peptidase (a nitrogen acquiring enzyme) Ea was not influenced by season. As temperatures rise, especially in winter months, enzymatic

Electricity generation and microbial community in response to short-term changes in stack connection of self-stacked submersible microbial fuel cell powered by glycerol

DEFF Research Database (Denmark)

Zhao, Nannan; Angelidaki, Irini; Zhang, Yifeng

2017-01-01

community. In this study, a self-stacked submersible microbial fuel cell (SSMFC) powered by glycerol was tested to elucidate this important issue. In series connection, the maximum voltage output reached to 1.15 V, while maximum current density was 5.73 mA in parallel. In both connections, the maximum power......Stack connection (i.e., in series or parallel) of microbial fuel cell (MFC) is an efficient way to boost the power output for practical application. However, there is little information available on short-term changes in stack connection and its effect on the electricity generation and microbial...... density increased with the initial glycerol concentration. However, the glycerol degradation was even faster in parallel connection. When the SSMFC was shifted from series to parallel connection, the reactor reached to a stable power output without any lag phase. Meanwhile, the anodic microbial community...

Increased diversity of egg-associated bacteria on brown trout (Salmo trutta) at elevated temperatures.

Science.gov (United States)

Wilkins, Laetitia G E; Rogivue, Aude; Schütz, Frédéric; Fumagalli, Luca; Wedekind, Claus

2015-11-27

The taxonomic composition of egg-associated microbial communities can play a crucial role in the development of fish embryos. In response, hosts increasingly influence the composition of their associated microbial communities during embryogenesis, as concluded from recent field studies and laboratory experiments. However, little is known about the taxonomic composition and the diversity of egg-associated microbial communities within ecosystems; e.g., river networks. We sampled late embryonic stages of naturally spawned brown trout at nine locations within two different river networks and applied 16S rRNA pyrosequencing to describe their bacterial communities. We found no evidence for a significant isolation-by-distance effect on the composition of bacterial communities, and no association between neutral genetic divergence of fish host (based on 11 microsatellites) and phylogenetic distances of the composition of their associated bacterial communities. We characterized core bacterial communities on brown trout eggs and compared them to corresponding water samples with regard to bacterial composition and its presumptive function. Bacterial diversity was positively correlated with water temperature at the spawning locations. We discuss this finding in the context of the increased water temperatures that have been recorded during the last 25 years in the study area.

Predicting long-term temperature increase for time-dependent SAR levels with a single short-term temperature response.

Science.gov (United States)

Carluccio, Giuseppe; Bruno, Mary; Collins, Christopher M

2016-05-01

Present a novel method for rapid prediction of temperature in vivo for a series of pulse sequences with differing levels and distributions of specific energy absorption rate (SAR). After the temperature response to a brief period of heating is characterized, a rapid estimate of temperature during a series of periods at different heating levels is made using a linear heat equation and impulse-response (IR) concepts. Here the initial characterization and long-term prediction for a complete spine exam are made with the Pennes' bioheat equation where, at first, core body temperature is allowed to increase and local perfusion is not. Then corrections through time allowing variation in local perfusion are introduced. The fast IR-based method predicted maximum temperature increase within 1% of that with a full finite difference simulation, but required less than 3.5% of the computation time. Even higher accelerations are possible depending on the time step size chosen, with loss in temporal resolution. Correction for temperature-dependent perfusion requires negligible additional time and can be adjusted to be more or less conservative than the corresponding finite difference simulation. With appropriate methods, it is possible to rapidly predict temperature increase throughout the body for actual MR examinations. © 2015 Wiley Periodicals, Inc.

Microbial C:P stoichiometry is shaped by redox conditions along an elevation gradient in humid tropical rainforests

Science.gov (United States)

Lin, Y.; Gross, A.; Silver, W. L.

2017-12-01

Elemental stoichiometry of microorganisms is intimately related to ecosystem carbon and nutrient fluxes and is ultimately controlled by the chemical (plant tissue, soil, redox) and physical (temperature, moisture, aeration) environment. Previous meta-analyses have shown that the C:P ratio of soil microbial biomass exhibits significant variations among and within biomes. Little is known about the underlying causes of this variability. We examined soil microbial C:P ratios along an elevation gradient in the Luquillo Experimental Forest in Puerto Rico. We analyzed soils from mixed forest paired with monodominant palm forest every 100 m from 300 m to 1000 m a.s.l.. Mean annual precipitation increased with increasing elevation, resulting in stronger reducing conditions and accumulation of soil Fe(II) at higher elevations. The mean value and variability of soil microbial C:P ratios generally increased with increasing elevation except at 1000 m. At high elevations (600-900 m), the average value of microbial C:P ratio (108±10:1) was significantly higher than the global average ( 55:1). We also found that soil organic P increased with increasing elevation, suggesting that an inhibition of organic P mineralization, not decreased soil P availability, may cause the high microbial C:P ratio. The soil microbial C:P ratio was positively correlated with soil HCl-extractable Fe(II), suggesting that reducing conditions may be responsible for the elevational changes observed. In a follow-up experiment, soils from mixed forests at four elevation levels (300, 500, 700, and 1000 m) were incubated under aerobic and anaerobic conditions for two weeks. We found that anaerobic incubation consistently increased the soil microbial C:P ratio relative to the aerobic incubation. Overall, our results indicate that redox conditions can shift the elemental composition of microbial biomass. The high microbial C:P ratios induced under anoxic conditions may reflect inhibition of microbial P

Microbial interactions: ecology in a molecular perspective.

Science.gov (United States)

Braga, Raíssa Mesquita; Dourado, Manuella Nóbrega; Araújo, Welington Luiz

2016-12-01

The microorganism-microorganism or microorganism-host interactions are the key strategy to colonize and establish in a variety of different environments. These interactions involve all ecological aspects, including physiochemical changes, metabolite exchange, metabolite conversion, signaling, chemotaxis and genetic exchange resulting in genotype selection. In addition, the establishment in the environment depends on the species diversity, since high functional redundancy in the microbial community increases the competitive ability of the community, decreasing the possibility of an invader to establish in this environment. Therefore, these associations are the result of a co-evolution process that leads to the adaptation and specialization, allowing the occupation of different niches, by reducing biotic and abiotic stress or exchanging growth factors and signaling. Microbial interactions occur by the transference of molecular and genetic information, and many mechanisms can be involved in this exchange, such as secondary metabolites, siderophores, quorum sensing system, biofilm formation, and cellular transduction signaling, among others. The ultimate unit of interaction is the gene expression of each organism in response to an environmental (biotic or abiotic) stimulus, which is responsible for the production of molecules involved in these interactions. Therefore, in the present review, we focused on some molecular mechanisms involved in the microbial interaction, not only in microbial-host interaction, which has been exploited by other reviews, but also in the molecular strategy used by different microorganisms in the environment that can modulate the establishment and structuration of the microbial community. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Historical Responsibility for Climate Change - from countries emissions to contribution to temperature increase

Science.gov (United States)

Krapp, Mario; Gütschow, Johannes; Rocha, Marcia; Schaeffer, Michiel

2016-04-01

The notion of historical responsibility is central to the equity debate and the measure of responsibility as a countries' share of historical global emissions remains one of the essential parameters in so-called equity proposals, which attempt to distribute effort among countries in an equitable manner. The focus of this contribution is on the historical contribution of countries, but it takes it one step further: its general objective lies on estimating countries' contribution directly to the change in climate. The historical responsibility is not based on cumulative emissions but instead measured in terms of the countries' estimated contribution to the increase in global-mean surface-air temperature. This is achieved by (1) compiling a historical emissions dataset for the period from 1850 until 2012 for each individual Kyoto-greenhouse gas and each UNFCCC Party using a consistent methodology and (2) applying those historical emissions to a revised version of the so-called Policy-maker Model put forward by the Ministry of Science and Technology of the Federative Republic of Brazil, which is a simple, yet powerful tool that allows historical GHG emissions of individual countries to be directly related to their effect on global temperature changes. We estimate that the cumulative GHG emissions until 2012 from the USA, the European Union and China contribute to a total temperature increase of about 0.50°C in 2100, which is equivalent to about 50% of the temperature increase from total global GHG emissions by that year (of about 1.0°C). Respectively, the USA, the European Union, and China are responsible for 20.2%, 17.3%, and 12.1% of global temperature increase in 2100. Russian historical emissions are responsible for 0.06°C temperature increase by 2100, ranking as the fourth largest contributor to temperature increase with 6.2% of the total contribution. India ranks fifth: Indian emissions to date would contribute to roughly 0.05°C of global mean temperature

The Deep-Sea Microbial Community from the Amazonian Basin Associated with Oil Degradation

Directory of Open Access Journals (Sweden)

Mariana E. Campeão

2017-06-01

Full Text Available One consequence of oil production is the possibility of unplanned accidental oil spills; therefore, it is important to evaluate the potential of indigenous microorganisms (both prokaryotes and eukaryotes from different oceanic basins to degrade oil. The aim of this study was to characterize the microbial response during the biodegradation process of Brazilian crude oil, both with and without the addition of the dispersant Corexit 9500, using deep-sea water samples from the Amazon equatorial margin basins, Foz do Amazonas and Barreirinhas, in the dark and at low temperatures (4°C. We collected deep-sea samples in the field (about 2570 m below the sea surface, transported the samples back to the laboratory under controlled environmental conditions (5°C in the dark and subsequently performed two laboratory biodegradation experiments that used metagenomics supported by classical microbiological methods and chemical analysis to elucidate both taxonomic and functional microbial diversity. We also analyzed several physical–chemical and biological parameters related to oil biodegradation. The concomitant depletion of dissolved oxygen levels, oil droplet density characteristic to oil biodegradation, and BTEX concentration with an increase in microbial counts revealed that oil can be degraded by the autochthonous deep-sea microbial communities. Indigenous bacteria (e.g., Alteromonadaceae, Colwelliaceae, and Alcanivoracaceae, archaea (e.g., Halobacteriaceae, Desulfurococcaceae, and Methanobacteriaceae, and eukaryotic microbes (e.g., Microsporidia, Ascomycota, and Basidiomycota from the Amazonian margin deep-sea water were involved in biodegradation of Brazilian crude oil within less than 48-days in both treatments, with and without dispersant, possibly transforming oil into microbial biomass that may fuel the marine food web.

Influence of composting techniques on microbial succession ...

African Journals Online (AJOL)

pH also stabilized as the composting process progressed in the pit. Good quality compost was obtained in 5 weeks when PACT was used. Conventional pit method lasted over several weeks. Key Words: Municipal wastes; passive aeration; pit composting; temperature; microbial succession. African Journal of Biotechnology ...

Maximum in the middle: nonlinear response of microbial plankton to ultraviolet radiation and phosphorus.

Directory of Open Access Journals (Sweden)

Juan Manuel Medina-Sánchez

Full Text Available The responses of heterotrophic microbial food webs (HMFW to the joint action of abiotic stressors related to global change have been studied in an oligotrophic high-mountain lake. A 2×5 factorial design field experiment performed with large mesocosms for >2 months was used to quantify the dynamics of the entire HMFW (bacteria, heterotrophic nanoflagellates, ciliates, and viruses after an experimental P-enrichment gradient which approximated or surpassed current atmospheric P pulses in the presence vs. absence of ultraviolet radiation. HMFW underwent a mid-term (<20 days acute development following a noticeable unimodal response to P enrichment, which peaked at intermediate P-enrichment levels and, unexpectedly, was more accentuated under ultraviolet radiation. However, after depletion of dissolved inorganic P, the HMFW collapsed and was outcompeted by a low-diversity autotrophic compartment, which constrained the development of HMFW and caused a significant loss of functional biodiversity. The dynamics and relationships among variables, and the response patterns found, suggest the importance of biotic interactions (predation/parasitism and competition in restricting HMFW development, in contrast to the role of abiotic factors as main drivers of autotrophic compartment. The response of HMFW may contribute to ecosystem resilience by favoring the maintenance of the peculiar paths of energy and nutrient-mobilization in these pristine ecosystems, which are vulnerable to threats by the joint action of abiotic stressors related to global change.

Effects of hydraulic frac fluids and formation waters on groundwater microbial communities

Science.gov (United States)

Krueger, Martin; Jimenez, Nuria

2017-04-01

Shale gas is being considered as a complementary energy resource to other fossil fuels. Its exploitation requires using advanced drilling techniques and hydraulic stimulation (fracking). During fracking operations, large amounts of fluids (fresh water, proppants and chemicals) are injected at high pressures into the formations, to create fractures and fissures, and thus to release gas from the source rock into the wellbore. The injected fluid partly remains in the formation, while up to 40% flows back to the surface, together with reservoir waters, sometimes containing dissolved hydrocarbons, high salt concentrations, etc. The aim of our study was to investigate the potential impacts of frac or geogenic chemicals, frac fluid, formation water or flowback on groudnwater microbial communities. Laboratory experiments under in situ conditions (i.e. at in situ temperature, high pressure) were conducted using groundwater samples from three different locations. Series of microcosms containing R2 broth medium or groundwater spiked with either single frac chemicals (including biocides), frac fluids, artificial reservoir water, NaCl, or different mixtures of reservoir water and frac fluid (to simulate flowback) were incubated in the dark. Controls included non-amended and non-inoculated microcosms. Classical microbiological methods and molecular analyses were used to assess changes in the microbial abundance, community structure and function in response to the different treatments. Microbial communities were quite halotolerant and their growth benefited from low concentrations of reservoir waters or salt, but they were negatively affected by higher concentrations of formation waters, salt, biocides or frac fluids. Changes on the microbial community structure could be detected by T-RFLP. Single frac components like guar gum or choline chloride were used as substrates, while others like triethanolamine or light oil distillate hydrogenated prevented microbial growth in

Microbial nitrogen cycling in Arctic snowpacks

International Nuclear Information System (INIS)

Larose, Catherine; Vogel, Timothy M; Dommergue, Aurélien

2013-01-01

Arctic snowpacks are often considered as chemical reactors for a variety of chemicals deposited through wet and dry events, but are overlooked as potential sites for microbial metabolism of reactive nitrogen species. The fate of deposited species is critical since warming leads to the transfer of contaminants to snowmelt-fed ecosystems. Here, we examined the role of microorganisms and the potential pathways involved in nitrogen cycling in the snow. Next generation sequencing data were used to follow functional gene abundances and a 16S rRNA (ribosomal ribonucleic acid) gene microarray was used to follow shifts in microbial community structure during a two-month spring-time field study at a high Arctic site, Svalbard, Norway (79° N). We showed that despite the low temperatures and limited water supply, microbial communities inhabiting the snow cover demonstrated dynamic shifts in their functional potential to follow several different pathways of the nitrogen cycle. In addition, microbial specific phylogenetic probes tracked different nitrogen species over time. For example, probes for Roseomonas tracked nitrate concentrations closely and probes for Caulobacter tracked ammonium concentrations after a delay of one week. Nitrogen cycling was also shown to be a dominant process at the base of the snowpack. (letter)

New directions in coral reef microbial ecology.

Science.gov (United States)

Garren, Melissa; Azam, Farooq

2012-04-01

Microbial processes largely control the health and resilience of coral reef ecosystems, and new technologies have led to an exciting wave of discovery regarding the mechanisms by which microbial communities support the functioning of these incredibly diverse and valuable systems. There are three questions at the forefront of discovery: What mechanisms underlie coral reef health and resilience? How do environmental and anthropogenic pressures affect ecosystem function? What is the ecology of microbial diseases of corals? The goal is to understand the functioning of coral reefs as integrated systems from microbes and molecules to regional and ocean-basin scale ecosystems to enable accurate predictions of resilience and responses to perturbations such as climate change and eutrophication. This review outlines recent discoveries regarding the microbial ecology of different microenvironments within coral ecosystems, and highlights research directions that take advantage of new technologies to build a quantitative and mechanistic understanding of how coral health is connected through microbial processes to its surrounding environment. The time is ripe for natural resource managers and microbial ecologists to work together to create an integrated understanding of coral reef functioning. In the context of long-term survival and conservation of reefs, the need for this work is immediate. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Simultaneous efficient removal of oxyfluorfen with electricity generation in a microbial fuel cell and its microbial community analysis.

Science.gov (United States)

Zhang, Qinghua; Zhang, Lei; Wang, Han; Jiang, Qinrui; Zhu, Xiaoyu

2018-02-01

The performance of a microbial fuel cell (MFC) to degrade oxyfluorfen was investigated. Approximately 77% of 50 mg/L oxyfluorfen was degraded within 24 h by anodic biofilm. The temperature, pH, and initial oxyfluorfen concentration had a significant effect on oxyfluorfen degrading, and a maximum degradation rate of 94.95% could theoretically be achieved at 31.96 °C, a pH of 7.65, and an initial oxyfluorfen concentration of 120.05 mg/L. Oxyfluorfen was further catabolized through various microbial metabolism pathways. Moreover, the anodic biofilm exhibited multiple catabolic capacities to 4-nitrophenol, chloramphenicol, pyraclostrobin, and sulfamethoxazole. Microbial community analysis indicated that functional bacteria Arcobacter, Acinetobacter, Azospirillum, Azonexus, and Comamonas were the predominant genera in the anodic biofilm. In terms of the efficient removal of various organic compounds and energy recovery, the MFC seemed to be a promising approach for the treatment of environmental contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2018-05-01

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

Microbial community responses to soil tillage and crop rotation in a corn/soybean agroecosystem.

Science.gov (United States)

Smith, Chris R; Blair, Peter L; Boyd, Charlie; Cody, Brianne; Hazel, Alexander; Hedrick, Ashley; Kathuria, Hitesh; Khurana, Parul; Kramer, Brent; Muterspaw, Kristin; Peck, Charles; Sells, Emily; Skinner, Jessica; Tegeler, Cara; Wolfe, Zoe

2016-11-01

The acreage planted in corn and soybean crops is vast, and these crops contribute substantially to the world economy. The agricultural practices employed for farming these crops have major effects on ecosystem health at a worldwide scale. The microbial communities living in agricultural soils significantly contribute to nutrient uptake and cycling and can have both positive and negative impacts on the crops growing with them. In this study, we examined the impact of the crop planted and soil tillage on nutrient levels, microbial communities, and the biochemical pathways present in the soil. We found that farming practice, that is conventional tillage versus no-till, had a much greater impact on nearly everything measured compared to the crop planted. No-till fields tended to have higher nutrient levels and distinct microbial communities. Moreover, no-till fields had more DNA sequences associated with key nitrogen cycle processes, suggesting that the microbial communities were more active in cycling nitrogen. Our results indicate that tilling of agricultural soil may magnify the degree of nutrient waste and runoff by altering nutrient cycles through changes to microbial communities. Currently, a minority of acreage is maintained without tillage despite clear benefits to soil nutrient levels, and a decrease in nutrient runoff-both of which have ecosystem-level effects and both direct and indirect effects on humans and other organisms.

Responses of soil microbial activity to cadmium pollution and elevated CO2.

Science.gov (United States)

Chen, Yi Ping; Liu, Qiang; Liu, Yong Jun; Jia, Feng An; He, Xin Hua

2014-03-06

To address the combined effects of cadmium (Cd) and elevated CO2 on soil microbial communities, DGGE (denaturing gradient gel electrophoresis) profiles, respiration, carbon (C) and nitrogen (N) concentrations, loessial soils were exposed to four levels of Cd, i.e., 0 (Cd0), 1.5 (Cd1.5), 3.0 (Cd3.0) and 6.0 (Cd6.0) mg Cd kg(-1) soil, and two levels of CO2, i.e., 360 (aCO2) and 480 (eCO2) ppm. Compared to Cd0, Cd1.5 increased fungal abundance but decreased bacterial abundance under both CO2 levels, whilst Cd3.0 and Cd6.0 decreased both fungal and bacterial abundance. Profiles of DGGE revealed alteration of soil microbial communities under eCO2. Soil respiration decreased with Cd concentrations and was greater under eCO2 than under aCO2. Soil total C and N were greater under higher Cd. These results suggest eCO2 could stimulate, while Cd pollution could restrain microbial reproduction and C decomposition with the restraint effect alleviated by eCO2.

Equal temperature-size responses of the sexes are widespread within arthropod species

DEFF Research Database (Denmark)

Hirst, Andrew G.; Horne, Curtis; Atkinson, David

2015-01-01

Sexual size dimorphism (SSD) is often affected by environmental conditions, but the effect of temperature on SSD in ectotherms still requires rigorous investigation. We compared the plastic responses of size-at-maturity to temperature between males and females within 85 diverse arthropod species...... of animal body sizes, variation in degree of SSD and differences in the sign of the T-S response. We find no support for Rensch's rule, which predicts greater variation in male size, or indeed the reverse, greater female size variation. SSD shows no systematic temperature dependence in any of the 17...

Sea Ice Microorganisms: Environmental Constraints and Extracellular Responses

Directory of Open Access Journals (Sweden)

Jody W. Deming

2013-03-01

Full Text Available Inherent to sea ice, like other high latitude environments, is the strong seasonality driven by changes in insolation throughout the year. Sea-ice organisms are exposed to shifting, sometimes limiting, conditions of temperature and salinity. An array of adaptations to survive these and other challenges has been acquired by those organisms that inhabit the ice. One key adaptive response is the production of extracellular polymeric substances (EPS, which play multiple roles in the entrapment, retention and survival of microorganisms in sea ice. In this concept paper we consider two main areas of sea-ice microbiology: the physico-chemical properties that define sea ice as a microbial habitat, imparting particular advantages and limits; and extracellular responses elicited in microbial inhabitants as they exploit or survive these conditions. Emphasis is placed on protective strategies used in the face of fluctuating and extreme environmental conditions in sea ice. Gaps in knowledge and testable hypotheses are identified for future research.

Studying Microbial Mat Functioning Amidst "Unexpected Diversity": Methodological Approaches and Initial Results from Metatranscriptomes of Mats Over Diel cycles, iTags from Long Term Manipulations, and Biogeochemical Cycling in Simplified Microbial Mats Constructed from Cultures

Science.gov (United States)

Bebout, B.; Bebout, L. E.; Detweiler, A. M.; Everroad, R. C.; Lee, J.; Pett-Ridge, J.; Weber, P. K.

2014-12-01

Microbial mats are famously amongst the most diverse microbial ecosystems on Earth, inhabiting some of the most inclement environments known, including hypersaline, dry, hot, cold, nutrient poor, and high UV environments. The high microbial diversity of microbial mats makes studies of microbial ecology notably difficult. To address this challenge, we have been using a combination of metagenomics, metatranscriptomics, iTags and culture-based simplified microbial mats to study biogeochemical cycling (H2 production, N2 fixation, and fermentation) in microbial mats collected from Elkhorn Slough, Monterey Bay, California. Metatranscriptomes of microbial mats incubated over a diel cycle have revealed that a number of gene systems activate only during the day in Cyanobacteria, while the remaining appear to be constitutive. The dominant cyanobacterium in the mat (Microcoleus chthonoplastes) expresses several pathways for nitrogen scavenging undocumented in cultured strains, as well as the expression of two starch storage and utilization cycles. Community composition shifts in response to long term manipulations of mats were assessed using iTags. Changes in community diversity were observed as hydrogen fluxes increased in response to a lowering of sulfate concentrations. To produce simplified microbial mats, we have isolated members of 13 of the 15 top taxa from our iTag libraries into culture. Simplified microbial mats and simple co-cultures and consortia constructed from these isolates reproduce many of the natural patterns of biogeochemical cycling in the parent natural microbial mats, but against a background of far lower overall diversity, simplifying studies of changes in gene expression (over the short term), interactions between community members, and community composition changes (over the longer term), in response to environmental forcing.

A Mosaic of Geothermal and Marine Features Shapes Microbial Community Structure on Deception Island Volcano, Antarctica

Directory of Open Access Journals (Sweden)

Amanda G. Bendia

2018-05-01

Full Text Available Active volcanoes in Antarctica contrast with their predominantly cold surroundings, resulting in environmental conditions capable of selecting for versatile and extremely diverse microbial communities. This is especially true on Deception Island, where geothermal, marine, and polar environments combine to create an extraordinary range of environmental conditions. Our main goal in this study was to understand how microbial community structure is shaped by gradients of temperature, salinity, and geochemistry in polar marine volcanoes. Thereby, we collected surface sediment samples associated with fumaroles and glaciers at two sites on Deception, with temperatures ranging from 0 to 98°C. Sequencing of the 16S rRNA gene was performed to assess the composition and diversity of Bacteria and Archaea. Our results revealed that Deception harbors a combination of taxonomic groups commonly found both in cold and geothermal environments of continental Antarctica, and also groups normally identified at deep and shallow-sea hydrothermal vents, such as hyperthermophilic archaea. We observed a clear separation in microbial community structure across environmental gradients, suggesting that microbial community structure is strongly niche driven on Deception. Bacterial community structure was significantly associated with temperature, pH, salinity, and chemical composition; in contrast, archaeal community structure was strongly associated only with temperature. Our work suggests that Deception represents a peculiar “open-air” laboratory to elucidate central questions regarding molecular adaptability, microbial evolution, and biogeography of extremophiles in polar regions.

Changes in the physicochemical and microbial quality of wastewater ...

African Journals Online (AJOL)

Changes in the physicochemical and microbial quality of wastewater from a ... different points of a treatment plant and bacterial isolates were obtained from them. ... The biological oxygen demand, dissolved oxygen, pH, temperature, turbidity, ...

Maximum in the middle: nonlinear response of microbial plankton to ultraviolet radiation and phosphorus.

Science.gov (United States)

Medina-Sánchez, Juan Manuel; Delgado-Molina, José Antonio; Bratbak, Gunnar; Bullejos, Francisco José; Villar-Argaiz, Manuel; Carrillo, Presentación

2013-01-01

The responses of heterotrophic microbial food webs (HMFW) to the joint action of abiotic stressors related to global change have been studied in an oligotrophic high-mountain lake. A 2×5 factorial design field experiment performed with large mesocosms for >2 months was used to quantify the dynamics of the entire HMFW (bacteria, heterotrophic nanoflagellates, ciliates, and viruses) after an experimental P-enrichment gradient which approximated or surpassed current atmospheric P pulses in the presence vs. absence of ultraviolet radiation. HMFW underwent a mid-term (ultraviolet radiation. However, after depletion of dissolved inorganic P, the HMFW collapsed and was outcompeted by a low-diversity autotrophic compartment, which constrained the development of HMFW and caused a significant loss of functional biodiversity. The dynamics and relationships among variables, and the response patterns found, suggest the importance of biotic interactions (predation/parasitism and competition) in restricting HMFW development, in contrast to the role of abiotic factors as main drivers of autotrophic compartment. The response of HMFW may contribute to ecosystem resilience by favoring the maintenance of the peculiar paths of energy and nutrient-mobilization in these pristine ecosystems, which are vulnerable to threats by the joint action of abiotic stressors related to global change.

Optimization of supercritical carbon dioxide treatment for the inactivation of the natural microbial flora in cubed cooked ham.

Science.gov (United States)

Ferrentino, Giovanna; Balzan, Sara; Spilimbergo, Sara

2013-02-15

This study aims to investigate the effects of supercritical carbon dioxide (SC-CO₂) treatment on the inactivation of the natural microbial flora in cubed cooked ham. Response surface methodology with a central composite design was applied to determine the optimal process conditions and investigate the effect of three independent variables (pressure, temperature and treatment time). Additionally, analyses of texture, pH and color together with a storage study of the product were performed to determine its microbial and qualitative stability. Response surface analysis revealed that 12 MPa, 50 °C, 5 min were the optimal conditions to obtain about 3.0, 1.6, and 2.5 Log(CFU/g) reductions of mesophilic aerobic bacteria, psychrophilic bacteria and lactic acid bacteria respectively. Inactivation to undetectable levels of yeasts and molds and coliforms was also obtained. A storage study of 30 days at 4 °C was carried out on the treated product (12 MPa, 50 °C, 5 min) monitoring microbial growth, pH, texture, and color parameters (L*, a*, b* and ΔE). Microbial loads slightly increased and after 30 days of storage reached the same levels detected in the fresh product. Color parameters (L*, a*, b*) showed slight variations while pH and texture did not change significantly. On the basis of the results obtained, SC-CO₂ can be considered a promising technique to microbiologically stabilize cubed cooked ham and, in general, cut/sliced meat products without affecting its quality attributes. Copyright © 2012 Elsevier B.V. All rights reserved.

Impact of drying-rewetting events on the response of soil microbial functions to dairyfibre and Miscanthus biochars

Science.gov (United States)

Bonnett, Sam; Vink, Stefanie; Baker, Kate; Saghir, Muhammad; Hornung, Andreas

2014-05-01

Biochar application has been shown to positively affect soil microbial functions such as reducing greenhouse gas emissions, increasing water/nutrient availability and increasing crop yields in tropical regions (Lehmann & Joseph, 2009). Understanding the dynamics of biochar application to soil microbial processes is critical for ensuring that soil quality, integrity and sustainability of the soil sub-system are maintained for crop growth. The aim of this British Ecological Society (BES) funded study was to examine the effect of two types of biochar on soil physicochemistry, GHG production, soil enzyme activities and microbial biomass in typical agricultural soil types and whether the effects were altered by drying, rewetting and flooding events. Miscanthus and dairyfibre (a mixture of straw and manure) feedstocks from Harper Adams University were pyrolyzed by Aston University at 450 °C using 100 kg/hr pyroformer technology. Two sieved soil types (sandy loam and clay loam) were mixed with dry biochar to produce 2 and 10 % w/w treatments for comparison with controls and maintained at 15 °C in temperature controlled incubators. At 0, 22, 44, 80, 101, and 114 days, soil was collected for determination of heterotrophic respiration, and microbial biomass by substrate-induced respiration (SIR), by gas headspace incubation and analysis of carbon dioxide (CO2) and nitrous oxide (N2O) by gas chromatography. Soil was sampled for the determination of water-extractable carbon, pH, and extracellular enzyme activities. Soil samples were maintained at field gravimetric water content between 0 and 44 days; air dried between 44 and 80 days; rewetted between 80 and 101 days; and flooded between 101 to 114 days. Results showed that the impact of biochar on soil microbial processes was dependent on biochar type and soil type, the level of biochar application and changes in soil moisture. Biochar affected soil pH particularly within the dairyfibre treatments, potentially due to the

Proteomic responses to elevated ocean temperature in ovaries of the ascidian Ciona intestinalis

Directory of Open Access Journals (Sweden)

Chelsea E. Lopez

2017-07-01

Full Text Available Ciona intestinalis, a common sea squirt, exhibits lower reproductive success at the upper extreme of the water temperatures it experiences in coastal New England. In order to understand the changes in protein expression associated with elevated temperatures, and possible response to global temperature change, we reared C. intestinalis from embryos to adults at 18°C (a temperature at which they reproduce normally at our collection site in Rhode Island and 22°C (the upper end of the local temperature range. We then dissected ovaries from animals at each temperature, extracted protein, and measured proteomic levels using shotgun mass spectrometry (LC-MS/MS. 1532 proteins were detected at a 1% false discovery rate present in both temperature groups by our LC-MS/MS method. 62 of those proteins are considered up- or down-regulated according to our statistical criteria. Principal component analysis shows a clear distinction in protein expression pattern between the control (18°C group and high temperature (22°C group. Similar to previous studies, cytoskeletal and chaperone proteins are upregulated in the high temperature group. Unexpectedly, we find evidence that proteolysis is downregulated at the higher temperature. We propose a working model for the high temperature response in C. intestinalis ovaries whereby increased temperature induces upregulation of signal transduction pathways involving PTPN11 and CrkL, and activating coordinated changes in the proteome especially in large lipid transport proteins, cellular stress responses, cytoskeleton, and downregulation of energy metabolism.

Preparation and properties of fast temperature-responsive soy protein/PNIPAAm IPN hydrogels

Directory of Open Access Journals (Sweden)

Liu Yong

2014-01-01

Full Text Available The interpenetrating polymer network of fast temperature-responsive hydrogels based on soy protein and poly(N-isopropylacrylamide were successfully prepared using the sodium bicarbonate (NaHCO3 solutions as the reaction medium. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermal gravimetric analysis. The swelling and deswelling kinetics were also investigated in detail. The results have shown that the proposed hydrogels had high porous structure, good miscibility and thermal stability, and fast temperature responsivity. The presence of NaHCO3 had little effect on the volume phase transition temperature (VPTT of the hydrogels, and the VPTTs were at about 32°C. Compared with the traditional hydrogels, the proposed hydrogels had much faster swelling and deswelling rate. The swelling mechanism of the hydrogels was the non-Fickian diffusion. This fast temperature-responsive hydrogels may have potential applications in the field of biomedical materials.

Microbial Community Structure of Deep-sea Hydrothermal Vents on the Ultraslow Spreading Southwest Indian Ridge

Directory of Open Access Journals (Sweden)

Jian Ding

2017-06-01

Full Text Available Southwest Indian Ridge (SWIR is a typical oceanic ultraslow spreading ridge with intensive hydrothermal activities. The microbial communities in hydrothermal fields including primary producers to support the entire ecosystem by utilizing geochemical energy generated from rock-seawater interactions. Here we have examined the microbial community structures on four hydrothermal vents from SWIR, representing distinct characteristics in terms of temperature, pH and metal compositions, by using Illumina sequencing of the 16S small subunit ribosomal RNA (rRNA genes, to correlate bacterial and archaeal populations with the nature of the vents influenced by ultraslow spreading features. Epsilon-, Gamma-, Alpha-, and Deltaproteobacteria and members of the phylum Bacteroidetes and Planctomycetes, as well as Thaumarchaeota, Woesearchaeota, and Euryarchaeota were dominant in all the samples. Both bacterial and archaeal community structures showed distinguished patterns compared to those in the fast-spreading East Pacific Ridge or the slow-spreading Mid-Atlantic Ridge as previously reported. Furthermore, within SWIR, the microbial communities are highly correlated with the local temperatures. For example, the sulfur-oxidizing bacteria were dominant within bacteria from low-temperature vents, but were not represented as the dominating group recovered from high temperature (over 300°C venting chimneys in SWIR. Meanwhile, Thaumarchaeota, the ammonium oxidizing archaea, only showed high relative abundance of amplicons in the vents with high-temperature in SWIR. These findings provide insights on the microbial community in ultraslow spreading hydrothermal fields, and therefore assist us in the understanding of geochemical cycling therein.

Quantitative analysis of microbial biomass yield in aerobic bioreactor.

Science.gov (United States)

Watanabe, Osamu; Isoda, Satoru

2013-12-01

We have studied the integrated model of reaction rate equations with thermal energy balance in aerobic bioreactor for food waste decomposition and showed that the integrated model has the capability both of monitoring microbial activity in real time and of analyzing biodegradation kinetics and thermal-hydrodynamic properties. On the other hand, concerning microbial metabolism, it was known that balancing catabolic reactions with anabolic reactions in terms of energy and electron flow provides stoichiometric metabolic reactions and enables the estimation of microbial biomass yield (stoichiometric reaction model). We have studied a method for estimating real-time microbial biomass yield in the bioreactor during food waste decomposition by combining the integrated model with the stoichiometric reaction model. As a result, it was found that the time course of microbial biomass yield in the bioreactor during decomposition can be evaluated using the operational data of the bioreactor (weight of input food waste and bed temperature) by the combined model. The combined model can be applied to manage a food waste decomposition not only for controlling system operation to keep microbial activity stable, but also for producing value-added products such as compost on optimum condition. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Microbial response to oil enrichment in Gulf of Mexico sediment measured using a novel long-term benthic lander system

Directory of Open Access Journals (Sweden)

Beth N. Orcutt

2017-04-01

Full Text Available Weathered crude oil sank to the seafloor following the 'Deepwater Horizon' disaster in 2010, removing this oil from further physical and photo-chemical degradation processes and leaving benthic processes as the mechanisms for altering and remediating this hydrocarbon source. To quantify potential microbial oil degradation rates at the seafloor, and associated changes in sediment microbial community structure and pore fluid composition, we used a benthic lander system to deploy novel sediment flow-through chambers at a natural hydrocarbon seep in the Gulf of Mexico (at a depth of 1226 m in lease block GC600 roughly 265 km southwest of the 'Deepwater Horizon' wellhead (at 1500 m depth. Sediment amended with 20% unweathered crude oil had elevated rates of sulfate reduction over the course of the 5-month-long experiment as compared to an unamended control, yielding potential rates of sulfate reduction (600–800 mmol m–2 d–1 among the highest measured in hydrocarbon-influenced seafloor sediment. Oil amendment also stimulated methane production towards the end of the experiment, and led to slightly higher cell densities without significant changes in microbial community structure, based on 16S rRNA gene sequence libraries and fatty acid profiles. Assuming a link between sulfate reduction and hydrocarbon degradation, these results suggest that electron acceptor availability may become limiting in heavily oiled deep-sea environments, resulting in minimal degradation of deposited oil. This study provides unique data on seafloor sediment responses to oil deposition, and reveals the value of using observatories to fill the gap in understanding deep-sea microbial processes, especially for ephemeral and stochastic events such as oil spills.

BioDry: An Inexpensive, Low-Power Method to Preserve Aquatic Microbial Biomass at Room Temperature.

Science.gov (United States)

Tuorto, Steven J; Brown, Chris M; Bidle, Kay D; McGuinness, Lora R; Kerkhof, Lee J

2015-01-01

This report describes BioDry (patent pending), a method for reliably preserving the biomolecules associated with aquatic microbial biomass samples, without the need of hazardous materials (e.g. liquid nitrogen, preservatives, etc.), freezing, or bulky storage/sampling equipment. Gel electrophoresis analysis of nucleic acid extracts from samples treated in the lab with the BioDry method indicated that molecular integrity was protected in samples stored at room temperature for up to 30 days. Analysis of 16S/18S rRNA genes for presence/absence and relative abundance of microorganisms using both 454-pyrosequencing and TRFLP profiling revealed statistically indistinguishable communities from control samples that were frozen in liquid nitrogen immediately after collection. Seawater and river water biomass samples collected with a portable BioDry "field unit", constructed from off-the-shelf materials and a battery-operated pumping system, also displayed high levels of community rRNA preservation, despite a slight decrease in nucleic acid recovery over the course of storage for 30 days. Functional mRNA and protein pools from the field samples were also effectively conserved with BioDry, as assessed by respective RT-PCR amplification and western blot of ribulose-1-5-bisphosphate carboxylase/oxygenase. Collectively, these results demonstrate that BioDry can adequately preserve a suite of biomolecules from aquatic biomass at ambient temperatures for up to a month, giving it great potential for high resolution sampling in remote locations or on autonomous platforms where space and power are limited.

BioDry: An Inexpensive, Low-Power Method to Preserve Aquatic Microbial Biomass at Room Temperature.

Directory of Open Access Journals (Sweden)

Steven J Tuorto

Full Text Available This report describes BioDry (patent pending, a method for reliably preserving the biomolecules associated with aquatic microbial biomass samples, without the need of hazardous materials (e.g. liquid nitrogen, preservatives, etc., freezing, or bulky storage/sampling equipment. Gel electrophoresis analysis of nucleic acid extracts from samples treated in the lab with the BioDry method indicated that molecular integrity was protected in samples stored at room temperature for up to 30 days. Analysis of 16S/18S rRNA genes for presence/absence and relative abundance of microorganisms using both 454-pyrosequencing and TRFLP profiling revealed statistically indistinguishable communities from control samples that were frozen in liquid nitrogen immediately after collection. Seawater and river water biomass samples collected with a portable BioDry "field unit", constructed from off-the-shelf materials and a battery-operated pumping system, also displayed high levels of community rRNA preservation, despite a slight decrease in nucleic acid recovery over the course of storage for 30 days. Functional mRNA and protein pools from the field samples were also effectively conserved with BioDry, as assessed by respective RT-PCR amplification and western blot of ribulose-1-5-bisphosphate carboxylase/oxygenase. Collectively, these results demonstrate that BioDry can adequately preserve a suite of biomolecules from aquatic biomass at ambient temperatures for up to a month, giving it great potential for high resolution sampling in remote locations or on autonomous platforms where space and power are limited.

The response of soil carbon storage and microbially mediated carbon turnover to simulated climatic disturbance in a northern peatland forest. Revisiting the concept of soil organic matter recalcitrance

Energy Technology Data Exchange (ETDEWEB)

Kostka, Joel [Georgia Inst. of Technology, Atlanta, GA (United States)

2015-09-14

The goal of this project was to investigate changes in the structure of dissolved and solid phase organic matter, the production of CO₂ and CH₄, and the composition of decomposer microbial communities in response to the climatic forcing of environmental processes that determine the balance between carbon gas production versus storage and sequestration in peatlands. Cutting-edge analytical chemistry and next generation sequencing of microbial genes were been applied to habitats at the Marcell Experimental Forest (MEF), where the US DOE’s Oak Ridge National Laboratory and the USDA Forest Service are constructing a large-scale ecosystem study entitled, “Spruce and Peatland Responses Under Climatic and Environmental Change”(SPRUCE). Our study represented a comprehensive characterization of the sources, transformation, and decomposition of organic matter in the S1 bog at MEF. Multiple lines of evidence point to distinct, vertical zones of organic matter transformation: 1) the acrotelm consisting of living mosses, root material, and newly formed litter (0-30 cm), 2) the mesotelm, a mid-depth transition zone (30-75 cm) characterized by labile organic C compounds and intense decomposition, and 3) the underlying catotelm (below 75cm) characterized by refractory organic compounds as well as relatively low decomposition rates. These zones are in part defined by physical changes in hydraulic conductivity and water table depth. O-alkyl-C, which represents the carbohydrate fraction in the peat, was shown to be an excellent proxy for soil decomposition rates. The carbon cycle in deep peat was shown to be fueled by modern carbon sources further indicating that hydrology and surface vegetation play a role in belowground carbon cycling. We provide the first metagenomic study of an ombrotrophic peat bog, with novel insights into microbial specialization and functions in this unique terrestrial ecosystem. Vertical structuring of microbial communities

Sponge-microbe associations survive high nutrients and temperatures.

Directory of Open Access Journals (Sweden)

Rachel Simister

Full Text Available Coral reefs are under considerable pressure from global stressors such as elevated sea surface temperature and ocean acidification, as well as local factors including eutrophication and poor water quality. Marine sponges are diverse, abundant and ecologically important components of coral reefs in both coastal and offshore environments. Due to their exceptionally high filtration rates, sponges also form a crucial coupling point between benthic and pelagic habitats. Sponges harbor extensive microbial communities, with many microbial phylotypes found exclusively in sponges and thought to contribute to the health and survival of their hosts. Manipulative experiments were undertaken to ascertain the impact of elevated nutrients and seawater temperature on health and microbial community dynamics in the Great Barrier Reef sponge Rhopaloeides odorabile. R. odorabile exposed to elevated nutrient levels including 10 µmol/L total nitrogen at 31°C appeared visually similar to those maintained under ambient seawater conditions after 7 days. The symbiotic microbial community, analyzed by 16S rRNA gene pyrotag sequencing, was highly conserved for the duration of the experiment at both phylum and operational taxonomic unit (OTU (97% sequence similarity levels with 19 bacterial phyla and 1743 OTUs identified across all samples. Additionally, elevated nutrients and temperatures did not alter the archaeal associations in R. odorabile, with sequencing of 16S rRNA gene libraries revealing similar Thaumarchaeota diversity and denaturing gradient gel electrophoresis (DGGE revealing consistent amoA gene patterns, across all experimental treatments. A conserved eukaryotic community was also identified across all nutrient and temperature treatments by DGGE. The highly stable microbial associations indicate that R. odorabile symbionts are capable of withstanding short-term exposure to elevated nutrient concentrations and sub-lethal temperatures.

Bar-coded pyrosequencing reveals the responses of PBDE-degrading microbial communities to electron donor amendments.

Directory of Open Access Journals (Sweden)

Meiying Xu

Full Text Available Polybrominated diphenyl ethers (PBDEs can be reductively degraded by microorganisms under anaerobic conditions. However, little is known about the effect of electron donors on microbial communities involved in PBDEs degradation. Here we employed 454 Titanium pyrosequencing to examine the phylogenetic diversity, composition, structure and dynamics of microbial communities from microcosms under the conditions of different electron donor amendments. The community structures in each of the five alternate electron donor enrichments were significantly shifted in comparison with those of the control microcosm. Commonly existing OTUs between the treatment and control consortia increased from 5 to 17 and more than 50% of OTUs increased around 13.7 to 186 times at least in one of the microcosms after 90-days enrichment. Although the microbial communities at different taxonomic levels were significantly changed by different environmental variable groups in redundancy analysis, significant correlations were observed between the microbial communities and PBDE congener profiles. The lesser-brominated PBDE congeners, tri-BDE congener (BDE-32 and hexa-BDE, were identified as the key factors shaping the microbial community structures at OTU level. Some rare populations, including the known dechlorinating bacterium, Dehalobacter, showed significant positive-correlation with the amounts of PBDE congeners in the consortia. The same results were also observed on some unclassified bacteria. These results suggest that PBDEs-degrading microbial communities can be successfully enriched, and their structures and compositions can be manipulated through adjusting the environmental parameters.

Global Microbial Identifier

DEFF Research Database (Denmark)

Wielinga, Peter; Hendriksen, Rene S.; Aarestrup, Frank Møller

2017-01-01

) will likely also enable a much better understanding of the pathogenesis of the infection and the molecular basis of the host response to infection. But the full potential of these advances will only transpire if the data in this area become transferable and thereby comparable, preferably in open-source...... of microorganisms, for the identification of relevant genes and for the comparison of genomes to detect outbreaks and emerging pathogens. To harness the full potential of WGS, a shared global database of genomes linked to relevant metadata and the necessary software tools needs to be generated, hence the global...... microbial identifier (GMI) initiative. This tool will ideally be used in amongst others in the diagnosis of infectious diseases in humans and animals, in the identification of microorganisms in food and environment, and to track and trace microbial agents in all arenas globally. This will require...

Microbial planktonic communities in the Red Sea: high levels of spatial and temporal variability shaped by nutrient availability and turbulence

KAUST Repository

Pearman, John K.; Ellis, Joanne; Irigoien, Xabier; Yellepeddi, Sarma B.; Jones, Burton; Carvalho, Susana

2017-01-01

The semi-enclosed nature of the Red Sea (20.2°N-38.5°N) makes it a natural laboratory to study the influence of environmental gradients on microbial communities. This study investigates the composition and structure of microbial prokaryotes and eukaryotes using molecular methods, targeting ribosomal RNA genes across different regions and seasons. The interaction between spatial and temporal scales results in different scenarios of turbulence and nutrient conditions allowing for testing of ecological theory that categorizes the response of the plankton community to these variations. The prokaryotic reads are mainly comprised of Cyanobacteria and Proteobacteria (Alpha and Gamma), with eukaryotic reads dominated by Dinophyceae and Syndiniophyceae. Periodic increases in the proportion of Mamiellophyceae and Bacillariophyceae reads were associated with alterations in the physical oceanography leading to nutrient increases either through the influx of Gulf of Aden Intermediate Water (south in the fall) or through water column mixing processes (north in the spring). We observed that in general dissimilarity amongst microbial communities increased when nutrient concentrations were higher, whereas richness (observed OTUs) was higher in scenarios of higher turbulence. Maximum abundance models showed the differential responses of dominant taxa to temperature giving an indication how taxa will respond as waters become warmer and more oligotrophic.

Microbial planktonic communities in the Red Sea: high levels of spatial and temporal variability shaped by nutrient availability and turbulence

KAUST Repository

Pearman, John K.

2017-07-20

The semi-enclosed nature of the Red Sea (20.2°N-38.5°N) makes it a natural laboratory to study the influence of environmental gradients on microbial communities. This study investigates the composition and structure of microbial prokaryotes and eukaryotes using molecular methods, targeting ribosomal RNA genes across different regions and seasons. The interaction between spatial and temporal scales results in different scenarios of turbulence and nutrient conditions allowing for testing of ecological theory that categorizes the response of the plankton community to these variations. The prokaryotic reads are mainly comprised of Cyanobacteria and Proteobacteria (Alpha and Gamma), with eukaryotic reads dominated by Dinophyceae and Syndiniophyceae. Periodic increases in the proportion of Mamiellophyceae and Bacillariophyceae reads were associated with alterations in the physical oceanography leading to nutrient increases either through the influx of Gulf of Aden Intermediate Water (south in the fall) or through water column mixing processes (north in the spring). We observed that in general dissimilarity amongst microbial communities increased when nutrient concentrations were higher, whereas richness (observed OTUs) was higher in scenarios of higher turbulence. Maximum abundance models showed the differential responses of dominant taxa to temperature giving an indication how taxa will respond as waters become warmer and more oligotrophic.

Impact of an indigenous microbial enhanced oil recovery field trial on microbial community structure in a high pour-point oil reservoir

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fan; Zhang, Xiao-Tao; Hou, Du-Jie [China Univ. of Geosciences, Beijing (China). The Key Lab. of Marine Reservoir Evolution and Hydrocarbon Accumulation Mechanism; She, Yue-Hui [Yangtze Univ., Jingzhou, Hubei (China). College of Chemistry and Environmental Engineering; Huazhong Univ. of Science and Technology, Wuhan (China). College of Life Science and Technology; Li, Hua-Min [Beijing Bioscience Research Center (China); Shu, Fu-Chang; Wang, Zheng-Liang [Yangtze Univ., Jingzhou, Hubei (China). College of Chemistry and Environmental Engineering; Yu, Long-Jiang [Huazhong Univ. of Science and Technology, Wuhan (China). College of Life Science and Technology

2012-08-15

Based on preliminary investigation of microbial populations in a high pour-point oil reservoir, an indigenous microbial enhanced oil recovery (MEOR) field trial was carried out. The purpose of the study is to reveal the impact of the indigenous MEOR process on microbial community structure in the oil reservoir using 16Sr DNA clone library technique. The detailed monitoring results showed significant response of microbial communities during the field trial and large discrepancies of stimulated microorganisms in the laboratory and in the natural oil reservoir. More specifically, after nutrients injection, the original dominant populations of Petrobacter and Alishewanella in the production wells almost disappeared. The expected desirable population of Pseudomonas aeruginosa, determined by enrichment experiments in laboratory, was stimulated successfully in two wells of the five monitored wells. Unexpectedly, another potential population of Pseudomonas pseudoalcaligenes which were not detected in the enrichment culture in laboratory was stimulated in the other three monitored production wells. In this study, monitoring of microbial community displayed a comprehensive alteration of microbial populations during the field trial to remedy the deficiency of culture-dependent monitoring methods. The results would help to develop and apply more MEOR processes. (orig.)

Impact of an indigenous microbial enhanced oil recovery field trial on microbial community structure in a high pour-point oil reservoir.

Science.gov (United States)

Zhang, Fan; She, Yue-Hui; Li, Hua-Min; Zhang, Xiao-Tao; Shu, Fu-Chang; Wang, Zheng-Liang; Yu, Long-Jiang; Hou, Du-Jie

2012-08-01

Based on preliminary investigation of microbial populations in a high pour-point oil reservoir, an indigenous microbial enhanced oil recovery (MEOR) field trial was carried out. The purpose of the study is to reveal the impact of the indigenous MEOR process on microbial community structure in the oil reservoir using 16Sr DNA clone library technique. The detailed monitoring results showed significant response of microbial communities during the field trial and large discrepancies of stimulated microorganisms in the laboratory and in the natural oil reservoir. More specifically, after nutrients injection, the original dominant populations of Petrobacter and Alishewanella in the production wells almost disappeared. The expected desirable population of Pseudomonas aeruginosa, determined by enrichment experiments in laboratory, was stimulated successfully in two wells of the five monitored wells. Unexpectedly, another potential population of Pseudomonas pseudoalcaligenes which were not detected in the enrichment culture in laboratory was stimulated in the other three monitored production wells. In this study, monitoring of microbial community displayed a comprehensive alteration of microbial populations during the field trial to remedy the deficiency of culture-dependent monitoring methods. The results would help to develop and apply more MEOR processes.

Temperature-Responsive Smart Nanocarriers for Delivery Of Therapeutic Agents: Applications and Recent Advances.

Science.gov (United States)

Karimi, Mahdi; Sahandi Zangabad, Parham; Ghasemi, Alireza; Amiri, Mohammad; Bahrami, Mohsen; Malekzad, Hedieh; Ghahramanzadeh Asl, Hadi; Mahdieh, Zahra; Bozorgomid, Mahnaz; Ghasemi, Amir; Rahmani Taji Boyuk, Mohammad Reza; Hamblin, Michael R

2016-08-24

Smart drug delivery systems (DDSs) have attracted the attention of many scientists, as carriers that can be stimulated by changes in environmental parameters such as temperature, pH, light, electromagnetic fields, mechanical forces, etc. These smart nanocarriers can release their cargo on demand when their target is reached and the stimulus is applied. Using the techniques of nanotechnology, these nanocarriers can be tailored to be target-specific, and exhibit delayed or controlled release of drugs. Temperature-responsive nanocarriers are one of most important groups of smart nanoparticles (NPs) that have been investigated during the past decades. Temperature can either act as an external stimulus when heat is applied from the outside, or can be internal when pathological lesions have a naturally elevated termperature. A low critical solution temperature (LCST) is a special feature of some polymeric materials, and most of the temperature-responsive nanocarriers have been designed based on this feature. In this review, we attempt to summarize recent efforts to prepare innovative temperature-responsive nanocarriers and discuss their novel applications.

Accelerated microbial turnover but constant growth efficiency with warming in soil

Science.gov (United States)

Shannon B. Hagerty; Kees Jan van Groenigen; Steven D. Allison; Bruce A. Hungate; Egbert Schwartz; George W. Koch; Randall K. Kolka; Paul. Dijkstra

2014-01-01

Rising temperatures are expected to reduce global soil carbon (C) stocks, driving a positive feedback to climate change1-3. However, the mechanisms underlying this prediction are not well understood, including how temperature affects microbial enzyme kinetics, growth effiency (MGE), and turnover4,5. Here, in a laboratory...

Linking leach chemistry and microbiology of low-grade copper ore bioleaching at different temperatures

Science.gov (United States)

Jia, Yan; Sun, He-yun; Tan, Qiao-yi; Gao, Hong-shan; Feng, Xing-liang; Ruan, Ren-man

2018-03-01

The effects of temperature on chalcocite/pyrite oxidation and the microbial population in the bioleaching columns of a low-grade chalcocite ore were investigated in this study. Raffinate from the industrial bioleaching heap was used as an irrigation solution for columns operated at 20, 30, 45, and 60°C. The dissolution of copper and iron were investigated during the bioleaching processes, and the microbial community was revealed by using a high-throughput sequencing method. The genera of Ferroplasma, Acidithiobacillus, Leptospirillum, Acidiplasma, and Sulfobacillus dominated the microbial community, and the column at a higher temperature favored the growth of moderate thermophiles. Even though microbial abundance and activity were highest at 30°C, the column at a higher temperature achieved a much higher Cu leaching efficiency and recovery, which suggested that the promotion of chemical oxidation by elevated temperature dominated the dissolution of Cu. The highest pyrite oxidation percentage was detected at 45°C. Higher temperature resulted in precipitation of jarosite in columns, especially at 60°C. The results gave implications to the optimization of heap bioleaching of secondary copper sulfide in both enhanced chalcocite leaching and acid/iron balance, from the perspective of leaching temperature and affected microbial community and activity.

Temperature and relative humidity dependence of radiochromic film dosimeter response to gamma electron radiation

DEFF Research Database (Denmark)

McLaughlin, W.L.; Puhl, J.M.; Miller, A.

1995-01-01

on some earlier studies, their response functions have been reported to be dependent on the temperature and relative humidity during irradiation. The present study investigates differences in response over practical ranges of temperature, relative humidity, dose, and for different recent batches of films...... humidity) and should be calibrated under environmental conditions (temperature) at which they will be used routinely....

Response of the soil microbial community to imazethapyr application in a soybean field.

Science.gov (United States)

Xu, Jun; Guo, Liqun; Dong, Fengshou; Liu, Xingang; Wu, Xiaohu; Sheng, Yu; Zhang, Ying; Zheng, Yongquan

2013-01-01

The objective of this study was to determine the effects of imazethapyr on soil microbial communities combined with its effect on soybean growth. A short-term field experiment was conducted, and imazethapyr was applied to the soil at three different doses [1-fold, 10-fold, and 50-fold of the recommended field rate (H1, H10, H50)] during the soybean seedling period (with two leaves). Soil sampling was performed after 1, 7, 30, 60, 90, and 120 days of application to determine the imazethapyr concentration and microbial community structure by investigating phospholipid fatty acids (PLFA) and microbial biomass carbon (MBC). The half-lives of the imazethapyr in the field soil varied from 30.1 to 43.3 days. Imazethapyr at H1 was innocuous to soybean plants, but imazethapyr at H10 and H50 led to a significant inhibition in soybean plant height and leaf number. The soil MBC, total PLFA, and bacterial PLFA were decreased by the application of imazethapyr during the initial period and could recover by the end of the experiment. The ratio of Gram-negative/Gram-positive (GN/GP) bacteria during the three treatments went through increases and decreases, and then recovered at the end of the experiment. The fungal PLFA of all three treatments increased during the initial period and then declined, and only the fungal PLFA at H50 recovered by the end of the treatment. A principal component analysis (PCA) of the PLFA clearly separated the treatments and sampling times, and the results demonstrate that imazethapyr alters the microbial community structure. This is the first systemic study reporting the effects of imazethapyr on the soil microbial community structure under soybean field conditions.

Microbial shifts in the swine nasal microbiota in response to parenteral antimicrobial administration.

Science.gov (United States)

Zeineldin, Mohamed; Aldridge, Brian; Blair, Benjamin; Kancer, Katherine; Lowe, James

2018-05-24

The continuous administration of antimicrobials in swine production has been widely criticized with the increase of antimicrobial-resistant bacteria and dysbiosis of the beneficial microbial communities. While an increasing number of studies investigate the effects of antimicrobial administration on swine gastrointestinal microbiota biodiversity, the impact of their use on the composition and diversity of nasal microbial communities has not been widely explored. The objective of this study was to characterize the short-term impact of different parenteral antibiotics administration on the composition and diversity of nasal microbial communities in growing pigs. Five antimicrobial treatment groups, each consisting of four, eight-week old piglets, were administered one of the antimicrobials; Ceftiofur Crystalline free acid (CCFA), Ceftiofur hydrochloride (CHC), Tulathromycin (TUL), Oxytetracycline (OTC), and Procaine Penicillin G (PPG) at label dose and route. Individual deep nasal swabs were collected immediately before antimicrobial administration (control = day 0), and again on days 1, 3, 7, and 14 after dosing. The nasal microbiota across all the samples were dominated by Firmicutes, proteobacteria and Bacteroidetes. While, the predominant bacterial genera were Moraxella, Clostridium and Streptococcus. Linear discriminant analysis, showed a pronounced, antimicrobial-dependent microbial shift in the composition of nasal microbiota and over time from day 0. By day 14, the nasal microbial compositions of the groups receiving CCFA and OTC had returned to a distribution that closely resembled that observed on day 0. In contrast, pigs that received CHC, TUL and PPG appeared to deviate away from the day 0 composition by day 14. Based on our results, it appears that the impact of parenteral antibiotics on the swine nasal microbiota is variable and has a considerable impact in modulating the nasal microbiota structure. Our results will aid in developing alternative

Microbial degradation of Cold Lake Blend and Western Canadian select dilbits by freshwater enrichments.

Science.gov (United States)

Deshpande, Ruta S; Sundaravadivelu, Devi; Techtmann, Stephen; Conmy, Robyn N; Santo Domingo, Jorge W; Campo, Pablo