The Experts below are selected from a list of 30015 Experts worldwide ranked by ideXlab platform
Kartik Chandran - One of the best experts on this subject based on the ideXlab platform.
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differentiation in the Microbial Ecology and activity of suspended and attached bacteria in a nitritation anammox process
Biotechnology and Bioengineering, 2015Co-Authors: Hongkeun Park, Suneethi Sundar, Kartik ChandranAbstract:A directed differentiation between the biofilm and suspension was observed in the molecular Microbial Ecology and gene expression of different bacteria in a biofilm nitritation-anammox process operated at varying hydraulic residence times (HRT) and nitrogen loading rates (NLR). The highest degree of enrichment observed in the biofilm was of anaerobic ammonia-oxidizing bacteria (AMX) followed by that of Nitrospira spp. related nitrite-oxidizing bacteria (NOB). For AMX, a major shift from Candidatus "Brocadia fulgida" to Candidatus "Kuenenia stuttgartiensis" in both suspension and biofilm was observed with progressively shorter HRT, using discriminatory biomarkers targeting the hydrazine synthase (hzsA) gene. In parallel, expression of the hydrazine oxidoreductase gene (hzo), a functional biomarker for AMX energy metabolism, became progressively prominent in the biofilm. A marginal but statistically significant enrichment in the biofilm was observed for Nitrosomonas europaea related ammonia-oxidizing bacteria (AOB). In direct contrast to AMX, the gene expression of ammonia monooxygenase subunit A (amoA), a functional biomarker for AOB energy metabolism, progressively increased in suspension. Using gene expression and biomass concentration measures in conjunction, it was determined that signatures of AOB metabolism were primarily present in the biofilm throughout the study. On the other hand, AMX metabolism gradually shifted from being uniformly distributed in both the biofilm and suspension to primarily the biofilm at shorter HRTs and higher NLRs. These results therefore highlight the complexity and key differences in the Microbial Ecology, gene expression and activity between the biofilm and suspension of a nitritation-anammox process and the biokinetic and metabolic drivers for such niche segregation.
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Microbial Ecology of denitrification in biological wastewater treatment
Water Research, 2014Co-Authors: Huijie Lu, Kartik Chandran, David StenselAbstract:Globally, denitrification is commonly employed in biological nitrogen removal processes to enhance water quality. However, substantial knowledge gaps remain concerning the overall community structure, population dynamics and metabolism of different organic carbon sources. This systematic review provides a summary of current findings pertaining to the Microbial Ecology of denitrification in biological wastewater treatment processes. DNA fingerprinting-based analysis has revealed a high level of Microbial diversity in denitrification reactors and highlighted the impacts of carbon sources in determining overall denitrifying community composition. Stable isotope probing, fluorescence in situ hybridization, microarrays and meta-omics further link community structure with function by identifying the functional populations and their gene regulatory patterns at the transcriptional and translational levels. This review stresses the need to integrate Microbial Ecology information into conventional denitrification design and operation at full-scale. Some emerging questions, from physiological mechanisms to practical solutions, for example, eliminating nitrous oxide emissions and supplementing more sustainable carbon sources than methanol, are also discussed. A combination of high-throughput approaches is next in line for thorough assessment of wastewater denitrifying community structure and function. Though denitrification is used as an example here, this synergy between Microbial Ecology and process engineering is applicable to other biological wastewater treatment processes.
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distinctive Microbial Ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor
Biotechnology and Bioengineering, 2008Co-Authors: Joon Ho Ahn, Kartik ChandranAbstract:Biological nitrogen removal (BNR) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). The goal of this study was to investigate the Microbial Ecology, biokinetics, and stability of partial nitrification. Stable long-term partial nitrification resulting in 82.1 ± 17.2% ammonia oxidation, primarily to nitrite (77.3 ± 19.5% of the ammonia oxidized) was achieved in a lab-scale bioreactor by operation at a pH, dissolved oxygen and solids retention time of 7.5 ± 0.1, 1.54 ± 0.87 mg O2/L, and 3.0 days, respectively. Bioreactor ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) populations were most closely related to Nitrosomonas europaea and Nitrobacter spp., respectively. The AOB population fraction varied in the range 61 ± 45% and was much higher than the NOB fraction, 0.71 ± 1.1%. Using direct measures of bacterial concentrations in conjunction with independent activity measures and mass balances, the maximum specific growth rate (µmax), specific decay (b) and observed biomass yield coefficients (Yobs) for AOB were 1.08 ± 1.03 day−1, 0.32 ± 0.34 day−1, and 0.15 ± 0.06 mg biomass COD/mg N oxidized, respectively. Corresponding µmax, b, and Yobs values for NOB were 2.6 ± 2.05 day−1, 1.7 ± 1.9 day−1, and 0.04 ± 0.02 mg biomass COD/mg N oxidized, respectively. The results of this study demonstrate that the highly selective partial nitrification operating conditions enriched for a narrow diversity of rapidly growing AOB and NOB populations unlike conventional BNR reactors, which host a broader diversity of nitrifying bacteria. Further, direct measures of Microbial abundance enabled not only elucidation of mixed community Microbial Ecology but also estimation of key engineering parameters describing bioreactor systems supporting these communities. Biotechnol. Bioeng. 2008;100: 1078–1087. © 2008 Wiley Periodicals, Inc.
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distinctive Microbial Ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor
Biotechnology and Bioengineering, 2008Co-Authors: Joon Ho Ahn, Kartik ChandranAbstract:Biological nitrogen removal (BNR) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). The goal of this study was to investigate the Microbial Ecology, biokinetics, and stability of partial nitrification. Stable long-term partial nitrification resulting in 82.1 +/- 17.2% ammonia oxidation, primarily to nitrite (77.3 +/- 19.5% of the ammonia oxidized) was achieved in a lab-scale bioreactor by operation at a pH, dissolved oxygen and solids retention time of 7.5 +/- 0.1, 1.54 +/- 0.87 mg O(2)/L, and 3.0 days, respectively. Bioreactor ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) populations were most closely related to Nitrosomonas europaea and Nitrobacter spp., respectively. The AOB population fraction varied in the range 61 +/- 45% and was much higher than the NOB fraction, 0.71 +/- 1.1%. Using direct measures of bacterial concentrations in conjunction with independent activity measures and mass balances, the maximum specific growth rate (micro(max)), specific decay (b) and observed biomass yield coefficients (Y(obs)) for AOB were 1.08 +/- 1.03 day(-1), 0.32 +/- 0.34 day(-1), and 0.15 +/- 0.06 mg biomass COD/mg N oxidized, respectively. Corresponding micro(max), b, and Y(obs) values for NOB were 2.6 +/- 2.05 day(-1), 1.7 +/- 1.9 day(-1), and 0.04 +/- 0.02 mg biomass COD/mg N oxidized, respectively. The results of this study demonstrate that the highly selective partial nitrification operating conditions enriched for a narrow diversity of rapidly growing AOB and NOB populations unlike conventional BNR reactors, which host a broader diversity of nitrifying bacteria. Further, direct measures of Microbial abundance enabled not only elucidation of mixed community Microbial Ecology but also estimation of key engineering parameters describing bioreactor systems supporting these communities.
Josephine Z Rapp - One of the best experts on this subject based on the ideXlab platform.
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Microbial Ecology of the cryosphere sea ice and glacial habitats
Nature Reviews Microbiology, 2015Co-Authors: Antje Boetius, Alexandre M Anesio, Jody W Deming, Jill A Mikucki, Josephine Z RappAbstract:The Earth's cryosphere comprises those regions that are cold enough for water to turn into ice. Recent findings show that the icy realms of polar oceans, glaciers and ice sheets are inhabited by microorganisms of all three domains of life, and that temperatures below 0 °C are an integral force in the diversification of Microbial life. Cold-adapted microorganisms maintain key ecological functions in icy habitats: where sunlight penetrates the ice, photoautotrophy is the basis for complex food webs, whereas in dark subglacial habitats, chemoautotrophy reigns. This Review summarizes current knowledge of the Microbial Ecology of frozen waters, including the diversity of niches, the composition of Microbial communities at these sites and their biogeochemical activities.
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Microbial Ecology of the cryosphere sea ice and glacial habitats
Nature Reviews Microbiology, 2015Co-Authors: Antje Boetius, Alexandre M Anesio, Jody W Deming, Jill A Mikucki, Josephine Z RappAbstract:In this Review, Boetiuset al. summarize our current knowledge of the Microbial Ecology of Earth's frozen realms, including sea ice and glacial habitats. They describe the diversity of niches, the composition of Microbial communities at these sites and their biogeochemical activities. The Earth's cryosphere comprises those regions that are cold enough for water to turn into ice. Recent findings show that the icy realms of polar oceans, glaciers and ice sheets are inhabited by microorganisms of all three domains of life, and that temperatures below 0 °C are an integral force in the diversification of Microbial life. Cold-adapted microorganisms maintain key ecological functions in icy habitats: where sunlight penetrates the ice, photoautotrophy is the basis for complex food webs, whereas in dark subglacial habitats, chemoautotrophy reigns. This Review summarizes current knowledge of the Microbial Ecology of frozen waters, including the diversity of niches, the composition of Microbial communities at these sites and their biogeochemical activities.
Janet E Stout - One of the best experts on this subject based on the ideXlab platform.
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effect of monochloramine treatment on the Microbial Ecology of legionella and associated bacterial populations in a hospital hot water system
Systematic and Applied Microbiology, 2015Co-Authors: Julianne L Baron, Scott Duda, Kirk J Harris, Eric P Holinger, Mark J Stevens, Charles E Robertson, Kimberly A Ross, Norman R Pace, Janet E StoutAbstract:Opportunistic pathogens, including Legionella spp. and non-tuberculous mycobacteria, can thrive in building hot water systems despite municipal and traditional on-site chlorine disinfection. Monochloramine is a relatively new approach to on-site disinfection, but the microbiological impact of on-site chloramine use has not been well studied. We hypothesized that comparison of the Microbial Ecology associated with monochloramine treatment versus no on-site treatment would yield highly dissimilar bacterial communities. Hot water samples were collected monthly from 7 locations for three months from two buildings in a Pennsylvania hospital complex supplied with common municipal water: (1) a hospital administrative building (no on-site treatment) and (2) an adjacent acute-care hospital treated on-site with monochloramine to control Legionella spp. Water samples were subjected to DNA extraction, rRNA PCR, and 454 pyrosequencing. Stark differences in the microbiome of the chloraminated water and the control were observed. Bacteria in the treated samples were primarily Sphingomonadales and Limnohabitans, whereas Flexibacter and Planctomycetaceae predominated in untreated control samples. Serendipitously, one sampling month coincided with dysfunction of the on-site disinfection system that resulted in a Legionella bloom detected by sequencing and culture. This study also demonstrates the potential utility of high-throughput DNA sequencing to monitor Microbial Ecology in water systems.
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shift in the Microbial Ecology of a hospital hot water system following the introduction of an on site monochloramine disinfection system
PLOS ONE, 2014Co-Authors: Julianne L Baron, Scott Duda, Amit Vikram, Janet E Stout, Kyle BibbyAbstract:Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system Microbial Ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the Microbial Ecology of a hospital’s hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The Microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, Microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing Microbial Ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on Microbial Ecology and not solely specific target microorganisms.
Antje Boetius - One of the best experts on this subject based on the ideXlab platform.
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Microbial Ecology of the cryosphere sea ice and glacial habitats
Nature Reviews Microbiology, 2015Co-Authors: Antje Boetius, Alexandre M Anesio, Jody W Deming, Jill A Mikucki, Josephine Z RappAbstract:The Earth's cryosphere comprises those regions that are cold enough for water to turn into ice. Recent findings show that the icy realms of polar oceans, glaciers and ice sheets are inhabited by microorganisms of all three domains of life, and that temperatures below 0 °C are an integral force in the diversification of Microbial life. Cold-adapted microorganisms maintain key ecological functions in icy habitats: where sunlight penetrates the ice, photoautotrophy is the basis for complex food webs, whereas in dark subglacial habitats, chemoautotrophy reigns. This Review summarizes current knowledge of the Microbial Ecology of frozen waters, including the diversity of niches, the composition of Microbial communities at these sites and their biogeochemical activities.
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Microbial Ecology of the cryosphere sea ice and glacial habitats
Nature Reviews Microbiology, 2015Co-Authors: Antje Boetius, Alexandre M Anesio, Jody W Deming, Jill A Mikucki, Josephine Z RappAbstract:In this Review, Boetiuset al. summarize our current knowledge of the Microbial Ecology of Earth's frozen realms, including sea ice and glacial habitats. They describe the diversity of niches, the composition of Microbial communities at these sites and their biogeochemical activities. The Earth's cryosphere comprises those regions that are cold enough for water to turn into ice. Recent findings show that the icy realms of polar oceans, glaciers and ice sheets are inhabited by microorganisms of all three domains of life, and that temperatures below 0 °C are an integral force in the diversification of Microbial life. Cold-adapted microorganisms maintain key ecological functions in icy habitats: where sunlight penetrates the ice, photoautotrophy is the basis for complex food webs, whereas in dark subglacial habitats, chemoautotrophy reigns. This Review summarizes current knowledge of the Microbial Ecology of frozen waters, including the diversity of niches, the composition of Microbial communities at these sites and their biogeochemical activities.
Julianne L Baron - One of the best experts on this subject based on the ideXlab platform.
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effect of monochloramine treatment on the Microbial Ecology of legionella and associated bacterial populations in a hospital hot water system
Systematic and Applied Microbiology, 2015Co-Authors: Julianne L Baron, Scott Duda, Kirk J Harris, Eric P Holinger, Mark J Stevens, Charles E Robertson, Kimberly A Ross, Norman R Pace, Janet E StoutAbstract:Opportunistic pathogens, including Legionella spp. and non-tuberculous mycobacteria, can thrive in building hot water systems despite municipal and traditional on-site chlorine disinfection. Monochloramine is a relatively new approach to on-site disinfection, but the microbiological impact of on-site chloramine use has not been well studied. We hypothesized that comparison of the Microbial Ecology associated with monochloramine treatment versus no on-site treatment would yield highly dissimilar bacterial communities. Hot water samples were collected monthly from 7 locations for three months from two buildings in a Pennsylvania hospital complex supplied with common municipal water: (1) a hospital administrative building (no on-site treatment) and (2) an adjacent acute-care hospital treated on-site with monochloramine to control Legionella spp. Water samples were subjected to DNA extraction, rRNA PCR, and 454 pyrosequencing. Stark differences in the microbiome of the chloraminated water and the control were observed. Bacteria in the treated samples were primarily Sphingomonadales and Limnohabitans, whereas Flexibacter and Planctomycetaceae predominated in untreated control samples. Serendipitously, one sampling month coincided with dysfunction of the on-site disinfection system that resulted in a Legionella bloom detected by sequencing and culture. This study also demonstrates the potential utility of high-throughput DNA sequencing to monitor Microbial Ecology in water systems.
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shift in the Microbial Ecology of a hospital hot water system following the introduction of an on site monochloramine disinfection system
PLOS ONE, 2014Co-Authors: Julianne L Baron, Scott Duda, Amit Vikram, Janet E Stout, Kyle BibbyAbstract:Drinking water distribution systems, including premise plumbing, contain a diverse microbiological community that may include opportunistic pathogens. On-site supplemental disinfection systems have been proposed as a control method for opportunistic pathogens in premise plumbing. The majority of on-site disinfection systems to date have been installed in hospitals due to the high concentration of opportunistic pathogen susceptible occupants. The installation of on-site supplemental disinfection systems in hospitals allows for evaluation of the impact of on-site disinfection systems on drinking water system Microbial Ecology prior to widespread application. This study evaluated the impact of supplemental monochloramine on the Microbial Ecology of a hospital’s hot water system. Samples were taken three months and immediately prior to monochloramine treatment and monthly for the first six months of treatment, and all samples were subjected to high throughput Illumina 16S rRNA region sequencing. The Microbial community composition of monochloramine treated samples was dramatically different than the baseline months. There was an immediate shift towards decreased relative abundance of Betaproteobacteria, and increased relative abundance of Firmicutes, Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria and Actinobacteria. Following treatment, Microbial populations grouped by sampling location rather than sampling time. Over the course of treatment the relative abundance of certain genera containing opportunistic pathogens and genera containing denitrifying bacteria increased. The results demonstrate the driving influence of supplemental disinfection on premise plumbing Microbial Ecology and suggest the value of further investigation into the overall effects of premise plumbing disinfection strategies on Microbial Ecology and not solely specific target microorganisms.