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PubMed2005

Changes in enzymes activity, substrate utilization pattern and diversity of soil microbial communities under cadmium pollution.

Heavy metal pollution has received increasing attention in recent years mainly because of the public awareness of environmental issues. In this study we have evaluated the effect of cadmium (Cd) on enzymes activity, substrate utilization pattern and diversity of microbial communities in soil spiked with 0, 20, 40, 60, 80, and 100 mg/kg Cd, during 60 d of incubation at 25 degrees C. Enzyme activities determined at 0, 15, 30, 45, and 60 d after heavy metal application (DAA) showed marked declines for various Cd treatments, and up to 60 DAA, 100 mg/kg Cd resulted in 50.1%, 47.4%, and 39.8% decreases in soil urease, acid phosphatase and dehydrogenase activities, respectively to control. At 60 DAA, substrate utilization pattern of soil microbial communities determined by inoculating Biolog ECO plates indicated that Cd addition had markedly inhibited the functional activity of soil microbial communities and multivariate analysis of sole carbon source utilization showed significantly different utilization patterns for 80 and 100 mg/kg Cd treatments. The structural diversity of soil microbial communities assessed by PCR-DGGE method at 60 DAA, illustrated that DGGE patterns in soil simplified with increasing Cd concentration, and clustering of DGGE profiles for various Cd treatments revealed that they had more than 50% difference with that of control.

Acid Phosphatase↗
PubMed2005

Microbial community and biochemistry process in autosulfurotrophic denitrifying biofilm.

The 16S rDNA-based molecular technique was applied to analyze the microbial community of autotrophic denitrification bacteria in a biofilm developed on the surface of sulfur particles and then the biochemistry process involved in this biofilm was discussed based on the microbial community analysis. Six key operational taxonomy units were identified, which were all unknown species belonging to a wide range of bacteria from four major subdivisions (alpha, beta, gamma and delta) of the kingdom Proteobacteria and from the kingdom Chlorobia (green sulfur bacteria). One species was chemoautotrophic and related to Thiobacillus denitrificans, two species were photoautotrophic, and three were chemoheterotrophic. Contrary to expectation, T. denitrificans-like bacteria constituted only 32% of the microbial community. As a result of the study, the entire microbiology of the autosulfurotrophic denitrification process as well as the interactions between the different microbial groups in the biofilm may need to be reconsidered.

Biofilms↗
PubMed2006

Exocellular electron transfer in anaerobic microbial communities.

Exocellular electron transfer plays an important role in anaerobic microbial communities that degrade organic matter. Interspecies hydrogen transfer between microorganisms is the driving force for complete biodegradation in methanogenic environments. Many organic compounds are degraded by obligatory syntrophic consortia of proton-reducing acetogenic bacteria and hydrogen-consuming methanogenic archaea. Anaerobic microorganisms that use insoluble electron acceptors for growth, such as iron- and manganese-oxide as well as inert graphite electrodes in microbial fuel cells, also transfer electrons exocellularly. Soluble compounds, like humic substances, quinones, phenazines and riboflavin, can function as exocellular electron mediators enhancing this type of anaerobic respiration. However, direct electron transfer by cell-cell contact is important as well. This review addresses the mechanisms of exocellular electron transfer in anaerobic microbial communities. There are fundamental differences but also similarities between electron transfer to another microorganism or to an insoluble electron acceptor. The physical separation of the electron donor and electron acceptor metabolism allows energy conservation in compounds as methane and hydrogen or as electricity. Furthermore, this separation is essential in the donation or acceptance of electrons in some environmental technological processes, e.g. soil remediation, wastewater purification and corrosion.

Anaerobiosis↗
PubMed2005

Comparison of microbial community between two shallow freshwater lakes in middle Yangtze basin, East China.

In order to investigate the role of the microbial community in aquatic ecology and nutrient transformations in the development of eutrophication in large shallow freshwater lakes along Yangtze River, the microbial community in the depth-related sediment in Lake Chaohu and Lake Longganhu were compared. Lake Chaohu is one of the three most polluted lakes in China. However, the neighboring Lake Longganhu, a mesotrophic lake, is relatively pristine. The total phosphorous (TP) and total nitrogen (TN) concentration in water was detected at 0.193 mgl(-1) and 3.035 mgl(-1) for Lake Chaohu, 0.051 mgl(-1) and 0.774 mgl(-1) for Lake Longganhu, respectively. The population of the microorganisms with various ecological nutrient transforming functions (e.g. phosphate solubilizing, denitrifying and cellulose decomposing) and a batch of environmental parameters concerning the nutrient accumulating and transforming (e.g. total organic carbon, total nitrogen, and total phosphorous concentrations) were assayed in the depth-related sediment samples from several defined points in both lakes. The sediment samples from Lake Chaohu showed higher density of actinomycetes (P<0.05) and phosphate-solubilizing bacteria (P<0.001) and less profusion of denitrifying bacteria (P<0.05) and cellulolytic microbes (P<0.001), compared with those of Lake Longganhu. The data suggested that the current microbial community in the sediment of Lake Chaohu is in favor of sustaining or further accelerating the process of the lake eutrophication. A possible positive feedback loop which consists of sustained growth of microorganisms and gradual decline of lake eutrophic status is worth further discussing.

Actinobacteria↗
PubMed2006

Diversity, composition, and geographical distribution of microbial communities in California salt marsh sediments.

The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes.

Bacteria↗
PubMed2002

Microbial community of a saline mud volcano at San Biagio-Belpasso, Mt. Etna (Italy).

In San Biagio of Belpasso, approximately 20 km south of Mt. Etna, in the area of contact between volcanic and sedimentary formations, a number of small (3- 60 cm in diameter) active mud eruptions discharge CO2-rich gases, mud and NaCl brines. They can be described as mini-volcanoes owing to their typical conic shapes and continuously bubbling peak craters. Samples were collected from the active peak craters at a depth of 20 cm and DNA was immediately extracted and amplified with universal 16S rRNA gene-specific primers, followed by cloning procedure. A total of 140 bacterial clones obtained were screened and clustered by restriction fragment length polymorphism (RFLP) analysis. The pool of 16S rRNA sequences representing each RFLP cluster was subjected to phylogenetic analysis. All of the 33 sequences analysed were affiliated with the kingdom of Eubacteria; 28 sequences (77% of all clones) affiliated with the Proteobacteria, two sequences (19% of all clones) were affiliated with Actinobacteria and three sequences (4% of all clones) were affiliated with the Flexibacter-Cytophaga-Bacteroides division. The data obtained suggest that the microorganisms phylogenetically affiliated to autotrophic methane oxidizers and heterotrophic hydrocarbon degraders belonging to the gamma-subclass of Proteobacteria are major constituents of the microbial communities of the saline volcanic muds. Overall, the composition of the microbial community of the San Biagio mud volcano resembles the compositions of marine microbial communities, which might indicate that wind-blown seawater vapour acted as an inoculum for microbial community described in present work.

Base Sequence↗
PubMed2001

Analysis of the microbial communities on corroded concrete sewer pipes--a case study.

Conventional as well as molecular techniques have been used to determine the microbial communities present on the concrete walls of sewer pipes. The genetic fingerprint of the microbiota on corroded concrete sewer pipes was obtained by means of denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. The DGGE profiles of the bacterial communities present on the concrete surface changed as observed by shifts occurring at the level of the dominance of bands from non-corroded places to the most severely corroded places. By means of statistical tools, it was possible to distinguish two different groups, corresponding to the microbial communities on corroded and non-corroded surfaces, respectively. Characterization of the microbial communities indicated that the sequences of typical bands showed the highest level of identity to sequences from the bacterial strains Thiobacillus thiooxidans, Acidithiobacillus sp., Mycobacterium sp. and different heterotrophs belonging to the alpha-, beta- and gamma-Proteobacteria, Acidobacteria and Actinobacteria. In addition, the presence of N-acyl-homoserine lactone signal molecules was shown by two bio-assays of the biofilm on the concrete under the water level and at the most severely corroded places on the concrete surface of the sewer pipe.

Bacteria↗
PubMed2007

Quantitative and qualitative beta diversity measures lead to different insights into factors that structure microbial communities.

The assessment of microbial diversity and distribution is a major concern in environmental microbiology. There are two general approaches for measuring community diversity: quantitative measures, which use the abundance of each taxon, and qualitative measures, which use only the presence/absence of data. Quantitative measures are ideally suited to revealing community differences that are due to changes in relative taxon abundance (e.g., when a particular set of taxa flourish because a limiting nutrient source becomes abundant). Qualitative measures are most informative when communities differ primarily by what can live in them (e.g., at high temperatures), in part because abundance information can obscure significant patterns of variation in which taxa are present. We illustrate these principles using two 16S rRNA-based surveys of microbial populations and two phylogenetic measures of community beta diversity: unweighted UniFrac, a qualitative measure, and weighted UniFrac, a new quantitative measure, which we have added to the UniFrac website (http://bmf.colorado.edu/unifrac). These studies considered the relative influences of mineral chemistry, temperature, and geography on microbial community composition in acidic thermal springs in Yellowstone National Park and the influences of obesity and kinship on microbial community composition in the mouse gut. We show that applying qualitative and quantitative measures to the same data set can lead to dramatically different conclusions about the main factors that structure microbial diversity and can provide insight into the nature of community differences. We also demonstrate that both weighted and unweighted UniFrac measurements are robust to the methods used to build the underlying phylogeny.

Animals↗
PubMed2006

Influence of freeze-thaw stress on the structure and function of microbial communities and denitrifying populations in soil.

Microbial N2O release during the course of thawing of soil was investigated in model experiment focusing on denitrification, since freeze-thaw has been shown to cause significant physical and biological changes in soil, including a surge of N2O and CO2. The origin of these is still controversially discussed. The increase in denitrification after thawing may be attributed to the diffusion of organic substrates newly available to denitrifiers from disrupted soil aggregates, leading to an increase in microbial activity. Laboratory experiments with upper soil layer of a grassland were conducted in microcosms for real-time gas measurements during the entire phase of freeze and thaw. Shifts in microbial communities were evident on resolution of 16S and 18S rRNA genes and transcripts by denaturing gradient gel electrophoresis (DGGE). Microbial expression profiles were compared by RNA-arbitrarily primed PCR technique and subsequent resolution of amplified products on acrylamide gels. Differences in expression levels of periplasmic nitrate reductase gene (napA) and cytochrome cd1 nitrite reductase (nirS) were observed by most-probable-number-reverse transcription-PCR, with higher levels of expression occurring just after thawing began, followed by a decrease. napA and nirS DGGE profiles showed no change in banding patterns with fingerprints derived from DNA, whereas those derived from cDNA showed a clear succession of denitrifying bacteria, with the most complex pattern being observed at the end of the N2O surge. This study provides insight into the structural community changes and expression dynamics of denitrifiers as a result of freeze-thaw stress. Also, the results presented here support the belief that the gas fluxes observed during thawing is a result of freezing initiated high microbial activity.

Bacteria↗
PubMed2005

[Metabolic properties of the microbial community in the biofilters using biolog microplates].

It is very important to know the structure and metabolic function of the microbial community in a bioreactor in order to improve its performance. In this study, two biofilters, packed with wood chips and granular activated carbons respectively, were operated for 160 days to treat toluene gas. The metabolic profiles of the microbial communities in the biofilters were monitored using Biolog microplates periodically during the experiments. The metabolic activities of the microorganisms in both biofilters were observed to decrease during long-term operation. According to the results of principle components analysis, the metabolic profiles of the microbial communities did not change much in the former period of the operation, but they changed in the inlet layers on day 103 and changed throughout the filter beds on day 160. The variation of the metabolic profiles in both biofilters showed little difference, which suggested that the packing media had little effect on them during long-term operation. Among the 95 carbon sources in Biolog microplate, carboxylic acids and amino acids were much easier to be utilized by the microorganisms in the biofilters than the other carbon

Air Pollutants↗
PubMed2006

Microarray-based analysis of subnanogram quantities of microbial community DNAs by using whole-community genome amplification.

Microarray technology provides the opportunity to identify thousands of microbial genes or populations simultaneously, but low microbial biomass often prevents application of this technology to many natural microbial communities. We developed a whole-community genome amplification-assisted microarray detection approach based on multiple displacement amplification. The representativeness of amplification was evaluated using several types of microarrays and quantitative indexes. Representative detection of individual genes or genomes was obtained with 1 to 100 ng DNA from individual or mixed genomes, in equal or unequal abundance, and with 1 to 500 ng community DNAs from groundwater. Lower concentrations of DNA (as low as 10 fg) could be detected, but the lower template concentrations affected the representativeness of amplification. Robust quantitative detection was also observed by significant linear relationships between signal intensities and initial DNA concentrations ranging from (i) 0.04 to 125 ng (r2 = 0.65 to 0.99) for DNA from pure cultures as detected by whole-genome open reading frame arrays, (ii) 0.1 to 1,000 ng (r2 = 0.91) for genomic DNA using community genome arrays, and (iii) 0.01 to 250 ng (r2 = 0.96 to 0.98) for community DNAs from ethanol-amended groundwater using 50-mer functional gene arrays. This method allowed us to investigate the oligotrophic microbial communities in groundwater contaminated with uranium and other metals. The results indicated that microorganisms containing genes involved in contaminant degradation and immobilization are present in these communities, that their spatial distribution is heterogeneous, and that microbial diversity is greatly reduced in the highly contaminated environment.

Biomass↗
PubMed2003

Microbial community dynamics associated with rhizosphere carbon flow.

Root-deposited photosynthate (rhizodeposition) is an important source of readily available carbon (C) for microbes in the vicinity of growing roots. Plant nutrient availability is controlled, to a large extent, by the cycling of this and other organic materials through the soil microbial community. Currently, our understanding of microbial community dynamics associated with rhizodeposition is limited. We used a (13)C pulse-chase labeling procedure to examine the incorporation of rhizodeposition into individual phospholipid fatty acids (PLFAs) in the bulk and rhizosphere soils of greenhouse-grown annual ryegrass (Lolium multiflorum Lam. var. Gulf). Labeling took place during a growth stage in transition between active root growth and rapid shoot growth on one set of plants (labeling period 1) and 9 days later during the rapid shoot growth stage on another set of plants (labeling period 2). Temporal differences in microbial community composition were more apparent than spatial differences, with a greater relative abundance of PLFAs from gram-positive organisms (i15:0 and a15:0) in the second labeling period. Although more abundant, gram-positive organisms appeared to be less actively utilizing rhizodeposited C in labeling period 2 than in labeling period 1. Gram-negative bacteria associated with the 16:1omega5 PLFA were more active in utilizing (13)C-labeled rhizodeposits in the second labeling period than in the first labeling period. In both labeling periods, however, the fungal PLFA 18:2omega6,9 was the most highly labeled. These results demonstrate the effectiveness of using (13)C labeling and PLFA analysis to examine the microbial dynamics associated with rhizosphere C cycling by focusing on the members actively involved.

Carbon↗
PubMed1997

Dynamics of a microbial community associated with manure hot spots as revealed by phospholipid fatty acid analyses.

Microbial community dynamics associated with manure hot spots were studied by using a model system consisting of a gel-stabilized mixture of soil and manure, placed between layers of soil, during a 3-week incubation period. The microbial biomass, measured as the total amount of phospholipid fatty acids (PLFA), had doubled within a 2-mm distance from the soil-manure interface after 3 days. Principal-component analyses demonstrated that this increase was accompanied by reproducible changes in the composition of PLFA, indicating changes in the microbial community structure. The effect of the manure was strongest in the 2-mm-thick soil layer closest to the interface, in which the PLFA composition was statistically significantly different (P < 0.05) from that of the unaffected soil layers throughout the incubation period. An effect was also observed in the soil layer 2 to 4 mm from the interface. The changes in microbial biomass and community structure were mainly attributed to the diffusion of dissolved organic carbon from the manure. During the initial period of microbial growth, PLFA, which were already more abundant in the manure than in the soil, increased in the manure core and in the 2-mm soil layer closest to the interface. After day 3, the PLFA composition of these layers gradually became more similar to that of the soil. The dynamics of individual PLFA suggested that both taxonomic and physiological changes occurred during growth. Examples of the latter were decreases in the ratios of 16:1 omega 7t to 16:1 omega 7c and of cyclopropyl fatty acids to their respective precursors, indicating a more active bacterial community. An inverse relationship between bacterial PLFA and the eucaryotic 20:4 PLFA (arachidonic acid) suggested that grazing was important.

Animals↗
PubMed2006

Electricity generation and microbial community analysis of alcohol powered microbial fuel cells.

Two different microbial fuel cell (MFC) configurations were investigated for electricity production from ethanol and methanol: a two-chambered, aqueous-cathode MFC; and a single-chamber direct-air cathode MFC. Electricity was generated in the two-chamber system at a maximum power density typical of this system (40+/-2 mW/m2) and a Coulombic efficiency (CE) ranging from 42% to 61% using ethanol. When bacteria were transferred into a single-chamber MFC known to produce higher power densities with different substrates, the maximum power density increased to 488+/-12 mW/m2 (CE = 10%) with ethanol. The voltage generated exhibited saturation kinetics as a function of ethanol concentration in the two-chambered MFC, with a half-saturation constant (Ks) of 4.86 mM. Methanol was also examined as a possible substrate, but it did not result in appreciable electricity generation. Analysis of the anode biofilm and suspension from a two-chamber MFC with ethanol using 16S rDNA-based techniques indicated that bacteria with sequences similar to Proteobacterium Core-1 (33.3% of clone library sequences), Azoarcus sp. (17.4%), and Desulfuromonas sp. M76 (15.9%) were significant members of the anode chamber community. These results indicate that ethanol can be used for sustained electricity generation at room temperature using bacteria on the anode in a MFC.

Electric Power Supplies↗
PubMed2004

Serial analysis of ribosomal sequence tags (SARST): a high-throughput method for profiling complex microbial communities.

Two decades of culture-independent studies have confirmed that microbial communities represent the most complex and concentrated pool of phylogenetic diversity on the planet. There remains a need for innovative molecular tools that can further our knowledge of microbial diversity and its functional implications. We present the method and application of serial analysis of ribosomal sequence tags (SARST) as a novel tool for elucidating complex microbial communities, such as those found in soils and sediments. Serial analysis of ribosomal sequence tags uses a series of enzymatic reactions to amplify and ligate ribosomal sequence tags (RSTs) from bacterial small subunit rRNA gene (SSU rDNA) V1-regions into concatemers that are cloned and sequenced. This approach offers a significant increase in throughput over traditional SSU rDNA clone libraries, as up to 20 RSTs are obtained from each sequencing reaction. To test SARST and measure the bias associated with this approach, RST libraries were prepared from a defined mixture of pure cultures and from duplicate arctic soil DNA samples. The actual RST distribution reflected the theoretical composition of the original defined mixture. Data from duplicate soil libraries (1345 and 1217 RSTs, with 525 and 505 unique RSTs, respectively) indicated that replication provides a strongly correlated RST profile (r(2) = 0.80) and division-level distribution of RSTs (r(2) = 0.99). Using sequence data from abundant soil RSTs, we designed specific primers that successfully amplified a larger portion of the SSU rDNA for further phylogenetic analysis. These results suggest that SARST is a powerful approach for reproducible high-throughput profiling of microbial diversity amenable to medical, industrial or environmental microbiology applications.

Bacteria↗
PubMed2006

Microbial communities in the surface mucopolysaccharide layer and the black band microbial mat of black band-diseased Siderastrea siderea.

Microbial community profiles and species composition associated with two black band-diseased colonies of the coral Siderastrea siderea were studied by 16S rRNA-targeted gene cloning, sequencing, and amplicon-length heterogeneity PCR (LH-PCR). Bacterial communities associated with the surface mucopolysaccharide layer (SML) of apparently healthy tissues of the infected colonies, together with samples of the black band disease (BBD) infections, were analyzed using the same techniques for comparison. Gene sequences, ranging from 424 to 1,537 bp, were retrieved from all positive clones (n = 43 to 48) in each of the four clone libraries generated and used for comparative sequence analysis. In addition to LH-PCR community profiling, all of the clone sequences were aligned with LH-PCR primer sequences, and the theoretical lengths of the amplicons were determined. Results revealed that the community profiles were significantly different between BBD and SML samples. The SML samples were dominated by gamma-proteobacteria (53 to 64%), followed by beta-proteobacteria (18 to 21%) and alpha-proteobacteria (5 to 11%). In contrast, both BBD clone libraries were dominated by alpha-proteobacteria (58 to 87%), followed by verrucomicrobia (2 to 10%) and 0 to 6% each of delta-proteobacteria, bacteroidetes, firmicutes, and cyanobacteria. Alphaproteobacterial sequence types related to the bacteria associated with toxin-producing dinoflagellates were observed in BBD clone libraries but were not found in the SML libraries. Similarly, sequences affiliated with the family Desulfobacteraceae and toxin-producing cyanobacteria, both believed to be involved in BBD pathogenesis, were found only in BBD libraries. These data provide evidence for an association of numerous toxin-producing heterotrophic microorganisms with BBD of corals.

Animals↗
PubMed2006

The veterinary antibiotic oxytetracycline and Cu influence functional diversity of the soil microbial community.

There are increasing concerns over the effects of veterinary antibiotics and heavy metals in agricultural soils. The widely used veterinary antibiotic oxytetracycline (OTC), Cu and their combination on soil microbial community function were assessed with the Biolog method. The microbial community was extracted from the soil and exposed to a 0.85% sodium chloride solution containing OTC (0, 1, 5, 11, 43, 109 and 217 microM), or Cu (0, 10, 20, 100 and 300 microM), or combination of the two pollutants (OTC 0, 5, 11 microM and Cu 0, 20 microM). Functional diversity, evenness, average well color development (AWCD) and substrate utilization decreased significantly with increasing concentrations of OTC or Cu (p < 0.005). The critical concentrations were 11 microM for OTC and 20 microM for Cu. The combination of OTC and Cu significantly decreased Shannon's diversity, evenness and utilization of carbohydrates and carboxylic acids compared to individual one of the contaminants. The antibiotic OTC and Cu had significant negative effects on soil microbial community function, particularly when both pollutants were present.

Anti-Bacterial Agents↗
PubMed2005

Dynamic changes in environment condition and microbial community structure in trench and flat seabed sediments of Tokyo Bay, Japan.

Dynamic changes in the chemical environment in the bottom of overlying water and microbial community structure in trench and flat seabed sediments were evaluated during summer and autumn in Tokyo Bay, Japan, to elucidate the response of microbial community changes as a consequence of dredging activity. Quinone profile analysis was performed to evaluate the changes in microbial community structure in the sediments. Bottom shape and location of each station affected the chemical environment of the overlying water. The trench bottom shape had longer anoxic conditions than the flat bottom shape. Nitrogen and phosphorus concentrations affected the microbial density in the sediment. During anoxic conditions, the ubiquinone/menaquinone ratio (UQ/MK) was less than unity and increased with rising dissolved oxygen (DO) concentrations. The dominant quinone species in the trench and flat seabed sediments were MK with 6 and 7 isoprene units (MK-6 and MK-7) and UQ with 8 and 9 isoprene units (UQ-8 and UQ-9). MK-6 and UQ-8 containing bacteria might have a great influence on the sulfur cycle of the aquatic ecosystem. While, MK-7 and UQ-9 containing bacteria correlated with the deposition of phototropic bacteria cells onto the seabed sediment. The trench bottom shape contained higher concentrations of MK-6, MK-7, UQ-8 and UQ-9, especially during summer.

Bacteria↗