scholarly journals Metabolic flexibility allows bacterial habitat generalists to become dominant in a frequently disturbed ecosystem

2021 ◽  
Author(s):  
Ya-Jou Chen ◽  
Pok Man Leung ◽  
Jennifer L. Wood ◽  
Sean K. Bay ◽  
Philip Hugenholtz ◽  
...  
Keyword(s):  
Community Composition ◽  
Sulfide Oxidation ◽  
Microbial Community Composition ◽  
Ecological Theory ◽  
Distribution Patterns ◽  
Amplicon Sequencing ◽  
Habitat Disturbance ◽  
Rrna Gene ◽  
Habitat Generalist ◽  
Habitat Generalists

AbstractEcological theory suggests that habitat disturbance differentially influences distributions of habitat generalist and specialist species. While well-established for macroorganisms, this theory has rarely been explored for microorganisms. Here we tested these principles in permeable (sandy) sediments, ecosystems with much spatiotemporal variation in resource availability and physicochemical conditions. Microbial community composition and function were profiled in intertidal and subtidal sediments using 16S rRNA gene amplicon sequencing and metagenomics, yielding 135 metagenome-assembled genomes. Community composition and metabolic traits modestly varied with sediment depth and sampling date. Several taxa were highly abundant and prevalent in all samples, including within the orders Woeseiales and Flavobacteriales, and classified as habitat generalists; genome reconstructions indicate these taxa are highly metabolically flexible facultative anaerobes and adapt to resource variability by using different electron donors and acceptors. In contrast, obligately anaerobic taxa such as sulfate reducers and candidate lineage MBNT15 were less abundant overall and only thrived in more stable deeper sediments. We substantiated these findings by measuring three metabolic processes in these sediments; whereas the habitat generalist-associated processes of sulfide oxidation and fermentation occurred rapidly at all depths, the specialist-associated process of sulfate reduction was restricted to deeper sediments. A manipulative experiment also confirmed habitat generalists outcompete specialist taxa during simulated habitat disturbance. Together, these findings show metabolically flexible habitat generalists become dominant in highly dynamic environments, whereas metabolically constrained specialists are restricted to narrower niches. Thus, an ecological theory describing distribution patterns for macroorganisms likely extends to microorganisms. Such findings have broad ecological and biogeochemical ramifications.

scholarly journals Metabolic flexibility allows generalist bacteria to become dominant in a frequently disturbed ecosystem

2020 ◽  
Author(s):  
Ya-Jou Chen ◽  
Pok Man Leung ◽  
Sean K. Bay ◽  
Philip Hugenholtz ◽  
Adam J. Kessler ◽  
...  
Keyword(s):  
Resource Availability ◽  
Sulfide Oxidation ◽  
Microbial Community Composition ◽  
Ecological Theory ◽  
Distribution Patterns ◽  
Amplicon Sequencing ◽  
Habitat Disturbance ◽  
16S Amplicon Sequencing ◽  
Specialist Species ◽  
And Function

AbstractEcological theory suggests that habitat disturbance differentially influences distributions of generalist and specialist species. While well-established for macroorganisms, this theory has rarely been explored for microorganisms. Here we tested these principles in permeable (sandy) sediments, ecosystems with much spatiotemporal variation in resource availability and other conditions. Microbial community composition and function was profiled in intertidal and subtidal sediments using 16S amplicon sequencing and metagenomics, yielding 135 metagenome-assembled genomes. Microbial abundance and composition significantly differed with sediment depth and, to a lesser extent, sampling date. Several generalist taxa were highly abundant and prevalent in all samples, including within orders Woeseiales and Flavobacteriales; genome reconstructions indicate these facultatively anaerobic taxa are highly metabolically flexible and adapt to fluctuations in resource availability by using different electron donors and acceptors. In contrast, obligately anaerobic taxa such as sulfate reducers (Desulfobacterales, Desulfobulbales) and proposed candidate phylum MBNT15 were less abundant overall and only thrived in more stable deeper sediments. We substantiated these findings by measuring three metabolic processes in these sediments; whereas the generalist-associated processes of sulfide oxidation and hydrogenogenic fermentation occurred rapidly at all depths, the specialist-associated process of sulfate reduction was restricted to deeper sediments. In addition, a manipulative experiment confirmed generalists outcompete specialist taxa during simulated habitat disturbance. Altogether, these findings suggest that metabolically flexible taxa become dominant in these highly dynamic environments, whereas metabolic specialism restricts bacteria to narrower niches. Thus, an ecological theory describing distribution patterns for macroorganisms likely extends to microorganisms. Such findings have broad ecological and biogeochemical ramifications.

scholarly journals Do initial concentration and activated sludge seasonality affect pharmaceutical biotransformation rate constants?

2021 ◽  
Author(s):  
Tamara J. H. M. van Bergen ◽  
Ana B. Rios-Miguel ◽  
Tom M. Nolte ◽  
Ad M. J. Ragas ◽  
Rosalie van Zelm ◽  
...  
Keyword(s):  
Microbial Community ◽  
Activated Sludge ◽  
Community Composition ◽  
Rate Constants ◽  
Wastewater Treatment Plants ◽  
Microbial Community Composition ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Initial Concentration ◽  
Different Seasons

Abstract Pharmaceuticals find their way to the aquatic environment via wastewater treatment plants (WWTPs). Biotransformation plays an important role in mitigating environmental risks; however, a mechanistic understanding of involved processes is limited. The aim of this study was to evaluate potential relationships between first-order biotransformation rate constants (kb) of nine pharmaceuticals and initial concentration of the selected compounds, and sampling season of the used activated sludge inocula. Four-day bottle experiments were performed with activated sludge from WWTP Groesbeek (The Netherlands) of two different seasons, summer and winter, spiked with two environmentally relevant concentrations (3 and 30 nM) of pharmaceuticals. Concentrations of the compounds were measured by LC–MS/MS, microbial community composition was assessed by 16S rRNA gene amplicon sequencing, and kb values were calculated. The biodegradable pharmaceuticals were acetaminophen, metformin, metoprolol, terbutaline, and phenazone (ranked from high to low biotransformation rates). Carbamazepine, diatrizoic acid, diclofenac, and fluoxetine were not converted. Summer and winter inocula did not show significant differences in microbial community composition, but resulted in a slightly different kb for some pharmaceuticals. Likely microbial activity was responsible instead of community composition. In the same inoculum, different kb values were measured, depending on initial concentration. In general, biodegradable compounds had a higher kb when the initial concentration was higher. This demonstrates that Michealis-Menten kinetic theory has shortcomings for some pharmaceuticals at low, environmentally relevant concentrations and that the pharmaceutical concentration should be taken into account when measuring the kb in order to reliably predict the fate of pharmaceuticals in the WWTP. Key points • Biotransformation and sorption of pharmaceuticals were assessed in activated sludge. • Higher initial concentrations resulted in higher biotransformation rate constants for biodegradable pharmaceuticals. • Summer and winter inocula produced slightly different biotransformation rate constants although microbial community composition did not significantly change. Graphical abstract

scholarly journals Impact of inter- and intra-individual variation, sample storage and sampling fraction on human stool microbial community profiles

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6172 ◽  
Author(s):  
Yun Kit Yeoh ◽  
Zigui Chen ◽  
Mamie Hui ◽  
Martin C.S. Wong ◽  
Wendy C.S. Ho ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Individual Variation ◽  
Large Scale ◽  
Microbial Community Composition ◽  
Amplicon Sequencing ◽  
Relative Effect ◽  
Individual Variability ◽  
Rrna Gene ◽  
Sample Collection

Stools are commonly used as proxies for studying human gut microbial communities as sample collection is straightforward, cheap and non-invasive. In large-scale human population surveys, however, sample integrity becomes an issue as it is not logistically feasible for researchers to personally collect stools from every participant. Instead, participants are usually given guidelines on sample packaging and storage, and asked to deliver their stools to a centralised facility. Here, we tested a number of delivery conditions (temperature, duration and addition of preservative medium) and assessed their effects on stool microbial community composition using 16S rRNA gene amplicon sequencing. The largest source of variability in stool community composition was attributable to inter-individual differences regardless of delivery condition. Although the relative effect of delivery condition on community composition was small compared to inter-individual variability (1.6% vs. 60.5%, permutational multivariate analysis of variance [PERMANOVA]) and temporal variation within subjects over 10 weeks (5.2%), shifts in microbial taxa associated with delivery conditions were non-systematic and subject-specific. These findings indicated that it is not possible to model or accurately predict shifts in stool community composition associated with sampling logistics. Based on our findings, we recommend delivery of fresh, preservative-free stool samples to laboratories within 2 hr either at ambient or chilled temperatures to minimise perturbations to microbial community composition. In addition, subsamples from different fractions of the same stool displayed a small (3.3% vs. 72.6% inter-individual variation, PERMANOVA) but significant effect on community composition. Collection of larger sample volumes for homogenisation is recommended.

scholarly journals On giant shoulders: How a seamount affects the microbial community composition of seawater and sponges

2020 ◽  
Author(s):  
Kathrin Busch ◽  
Ulrike Hanz ◽  
Furu Mienis ◽  
Benjamin Müller ◽  
Andre Franke ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Dissolved Inorganic Carbon ◽  
Environmental Gradients ◽  
Microbial Community Composition ◽  
Geographic Location ◽  
Environmental Parameters ◽  
Amplicon Sequencing ◽  
The Arctic ◽  
Rrna Gene

Abstract. Seamounts represent ideal systems to study the influence and interdependency of environmental gradients at a single geographic location. These topographic features represent a prominent habitat for various forms of life, including microbiota and macrobiota, spanning benthic as well as pelagic organisms. While it is known that seamounts are globally abundant structures, it still remains unclear how and to which extend the complexity of the seafloor is intertwined with the local oceanographic mosaic, biogeochemistry and microbiology of a seamount ecosystem. Along these lines, the present study aimed to explore whether and to which extend seamounts can have an imprint on the microbial community composition of seawater and of sessile benthic invertebrates, sponges. For our high-resolution sampling approach of microbial diversity (16S rRNA gene Amplicon sequencing) along with measurements of inorganic nutrients and other biogeochemical parameters, we focused on the Schulz Bank seamount ecosystem, a sponge ground ecosystem which is located on the Arctic Mid-Ocean Ridge. Seawater samples were collected at two sampling depths (mid-water: MW, and near-bed water: BW) from a total of 19 sampling sites. With a clustering approach we defined microbial micro-habitats within the pelagic realm at Schulz Bank, which were mapped onto the seamount's topography, and related to various environmental parameters (such as suspended particulate matter (SPM), dissolved inorganic carbon (DIC), silicate (SiO4−), phosphate (PO43−), ammonia (NH4+), nitrate (NO32−), nitrite (NO2

scholarly journals Distinctive microbial communities in subzero hypersaline brines from Arctic coastal sea ice and rarely sampled cryopegs

2019 ◽  
Vol 95 (12) ◽  
Author(s):  
Zachary S Cooper ◽  
Josephine Z Rapp ◽  
Shelly D Carpenter ◽  
Go Iwahana ◽  
Hajo Eicken ◽  
...  
Keyword(s):  
Community Structure ◽  
Sea Ice ◽  
Community Composition ◽  
Microbial Community Composition ◽  
Environmental Parameters ◽  
Amplicon Sequencing ◽  
Diversity Indices ◽  
Extracellular Polysaccharides ◽  
Rrna Gene ◽  
Alpha And Beta Diversity

ABSTRACT Hypersaline aqueous environments at subzero temperatures are known to be inhabited by microorganisms, yet information on community structure in subzero brines is very limited. Near Utqiaġvik, Alaska, we sampled subzero brines (–6°C, 115–140 ppt) from cryopegs, i.e. unfrozen sediments within permafrost that contain relic (late Pleistocene) seawater brine, as well as nearby sea-ice brines to examine microbial community composition and diversity using 16S rRNA gene amplicon sequencing. We also quantified the communities microscopically and assessed environmental parameters as possible determinants of community structure. The cryopeg brines harbored surprisingly dense bacterial communities (up to 108 cells mL–1) and millimolar levels of dissolved and particulate organic matter, extracellular polysaccharides and ammonia. Community composition and diversity differed between the two brine environments by alpha- and beta-diversity indices, with cryopeg brine communities appearing less diverse and dominated by one strain of the genus Marinobacter, also detected in other cold, hypersaline environments, including sea ice. The higher density and trend toward lower diversity in the cryopeg communities suggest that long-term stability and other features of a subzero brine are more important selective forces than in situ temperature or salinity, even when the latter are extreme.

scholarly journals Host-associated microbe PCR (hamPCR) enables convenient measurement of both microbial load and community composition

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Derek S Lundberg ◽  
Pratchaya Pramoj Na Ayutthaya ◽  
Annett Strauß ◽  
Gautam Shirsekar ◽  
Wen-Sui Lo ◽  
...  
Keyword(s):  
Community Composition ◽  
Compositional Data ◽  
Microbial Community Composition ◽  
Amplicon Sequencing ◽  
Microbial Load ◽  
Rrna Gene ◽  
Substantial Cost ◽  
Culture Independent ◽  
Metagenome Sequencing ◽  
Single Amplicon

The ratio of microbial population size relative to the amount of host tissue, or 'microbial load', is a fundamental metric of colonization and infection, but it cannot be directly deduced from microbial amplicon data such as 16S rRNA gene counts. Because existing methods to determine load, such as serial dilution plating, quantitative PCR, and whole metagenome sequencing, add substantial cost and/or experimental burden, they are only rarely paired with amplicon sequencing. We introduce host-associated microbe PCR (hamPCR), a robust strategy to both quantify microbial load and describe interkingdom microbial community composition in a single amplicon library. We demonstrate its accuracy across multiple study systems, including nematodes and major crops, and further present a cost-saving technique to reduce host overrepresentation in the library prior to sequencing. Because hamPCR provides an accessible experimental solution to the well-known limitations and statistical challenges of compositional data, it has far-reaching potential in culture-independent microbiology.

scholarly journals Relationships between community composition, productivity and invasion resistance in semi-natural bacterial microcosms

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Matt Lloyd Jones ◽  
Damian William Rivett ◽  
Alberto Pascual-García ◽  
Thomas Bell
Keyword(s):  
Microbial Communities ◽  
Community Composition ◽  
Focal Point ◽  
Microbial Community Composition ◽  
Common Garden ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Invasion Resistance ◽  
Bacterial Strains ◽  
Microbial Invasion

Common garden experiments that inoculate a standardised growth medium with synthetic microbial communities (i.e. constructed from individual isolates or using dilution cultures) suggest that the ability of the community to resist invasions by additional microbial taxa can be predicted by the overall community productivity (broadly defined as cumulative cell density and/or growth rate). However, to the best of our knowledge, no common garden study has yet investigated the relationship between microbial community composition and invasion resistance in microcosms whose compositional differences reflect natural, rather than laboratory-designed, variation. We conducted experimental invasions of two bacterial strains (Pseudomonas fluorescens and Pseudomonas putida) into laboratory microcosms inoculated with 680 different mixtures of bacteria derived from naturally occurring microbial communities collected in the field. Using 16S rRNA gene amplicon sequencing to characterise microcosm starting composition, and high-throughput assays of community phenotypes including productivity and invader survival, we determined that productivity is a key predictor of invasion resistance in natural microbial communities, substantially mediating the effect of composition on invasion resistance. The results suggest that similar general principles govern invasion in artificial and natural communities, and that factors affecting resident community productivity should be a focal point for future microbial invasion experiments.

scholarly journals Do initial concentration and activated sludge seasonality affect pharmaceutical biodegradation rate constants?

2020 ◽  
Author(s):  
Tamara J.H.M. van Bergen ◽  
Ana B. Rios-Miguel ◽  
Tom M. Nolte ◽  
Ad M.J. Ragas ◽  
Rosalie van Zelm ◽  
...  
Keyword(s):  
Microbial Community ◽  
Activated Sludge ◽  
Community Composition ◽  
Rate Constants ◽  
Wastewater Treatment Plants ◽  
Microbial Community Composition ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Biodegradation Rate ◽  
Initial Concentration

AbstractPharmaceuticals find their way to the aquatic environment via wastewater treatment plants (WWTPs) and biodegradation plays an important role in mitigating environmental risks, however a mechanistic understanding of involved processes is limited. The aim of this study was to evaluate potential relationships between first-order biodegradation rate constants (kb) of nine pharmaceuticals and initial concentration of the selected compounds, and sampling season of the used activated sludge inocula. Four-day bottle experiments were performed with activated sludge from WWTP Groesbeek (The Netherlands) of two different seasons, summer and winter, spiked with two environmentally relevant concentrations (3 and 30 nM) of pharmaceuticals. Concentrations of the compounds were measured by LC-MS/MS, microbial community composition was assessed by 16S rRNA gene amplicon sequencing and kbvalues were calculated. The biodegradable pharmaceuticals, ranked from high to low biodegradation rates, were acetaminophen, metformin, metoprolol, terbutaline, and phenazone. Carbamazepine, diatrizoic acid, diclofenac and fluoxetine were not converted. Summer and winter inocula did not show significant differences in microbial community composition, but resulted in a slightly different kbfor some pharmaceuticals. Likely microbial activity was responsible instead of community composition. In the same inoculum different kbvalues were measured, depending on initial concentration. In general, biodegradable compounds had a higher kbwhen the initial concentration was higher. This demonstrates that Michealis-Menten kinetics theory has shortcomings for some pharmaceuticals at low, environmentally relevant concentrations and that the pharmaceutical concentration should be taken into account when measuring the kbin order to reliably predict the fate of pharmaceuticals in the WWTP.

scholarly journals Assessing species biomass contributions in microbial communities via metaproteomics

2017 ◽  
Author(s):  
Manuel Kleiner ◽  
Erin Thorson ◽  
Christine E. Sharp ◽  
Xiaoli Dong ◽  
Dan Liu ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Community Composition ◽  
Microbial Mats ◽  
Soda Lakes ◽  
Microbial Community Composition ◽  
Amplicon Sequencing ◽  
Rrna Gene ◽  
Cell Numbers

AbstractAssessment of microbial community composition is the cornerstone of microbial ecology. Microbial community composition can be analyzed by quantifying cell numbers or by quantifying biomass for individual populations. However, as cell volumes can differ by orders of magnitude, these two approaches yield vastly different results. Methods for quantifying cell numbers are already available (e.g. fluorescence in situ hybridization, 16S rRNA gene amplicon sequencing), yet methods for assessing community composition in terms of biomass are lacking.We developed metaproteomics based methods for assessing microbial community composition using protein abundance as a measure for biomass contributions of individual populations. We optimized the accuracy and sensitivity of the method using artificially assembled microbial communities and found that it is less prone to some of the biases found in sequencing-based methods. We applied the method using communities from two different environments, microbial mats from two alkaline soda lakes and saliva from multiple individuals.

scholarly journals Host-associated microbe PCR (hamPCR): accessing new biology through convenient measurement of both microbial load and community composition

2020 ◽  
Author(s):  
Derek S. Lundberg ◽  
Pratchaya Pramoj Na Ayutthaya ◽  
Annett Strauß ◽  
Gautam Shirsekar ◽  
Wen-Sui Lo ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Compositional Data ◽  
Microbial Community Composition ◽  
Cost Effective ◽  
Amplicon Sequencing ◽  
Microbial Load ◽  
Rrna Gene ◽  
Metagenome Sequencing ◽  
Transformative Approach

AbstractThe ratio of microbial population size relative to the amount of host tissue, or “microbial load”, is a fundamental metric of colonization and infection, but it cannot be directly deduced from microbial amplicon data such as 16S rRNA gene counts. Because conventional methods to determine load, such as serial dilution plating or quantitative PCR, add substantial experimental burden, they are only rarely paired with amplicon sequencing. Alternatively, whole metagenome sequencing of DNA contributed by host and microbes both reveals microbial community composition and enables determination of microbial load, but host DNA typically greatly outweighs microbial DNA, severely limiting the cost-effectiveness and scalability of this approach. We introduce host-associated microbe PCR (hamPCR), a robust amplicon sequencing strategy to quantify microbial load and describe interkingdom microbial community composition in a single, cost-effective library. We demonstrate its accuracy and flexibility across multiple host and microbe systems, including nematodes and major crops. We further present a technique that can be used, prior to sequencing, to optimize the host representation in a batch of libraries without loss of information. Because of its simplicity, and the fact that it provides an experimental solution to the well-known statistical challenges provided by compositional data, hamPCR will become a transformative approach throughout culture-independent microbiology.

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