Biofouling impacts seawater reverse osmosis (SWRO) desalination plants by hindering module performance, increasing energetic demands, and incurring further costs. Here we investigated the ...spatial–temporal dynamics of microbial communities along the feedwater, pretreatment, and reverse osmosis stages of a large-scale SWRO desalination facility. While the composition of water-based microbial communities varied seasonally, the composition of biofilm microbial communities clustered by locations. Proteobacteria dominated throughout the water and biofilm communities while other dominant phyla varied seasonally and spatially. The microbial community composition significantly differed along the pathway locations of feedwater, rapid sand filtration (RSF), cartridge filters (CF), and the reverse osmosis (RO) membranes. Biofilms on the RSF and CF were composed of more diverse microbial populations than RO biofilms as determined by the effective number of species. Biofilms that developed along the treatment pathway (CF) served as inocula enhancing biofouling downstream on the RO membranes. Subsequently, we believe that prior to the development of advanced antibiofouling treatments for the desalination industries, the site-specific microbial community of feedwater, pretreatment and RO biofouling should be characterized. Site specific identification of these communities will enable optimization of pretreatment and cleaning procedures and can ultimately reduce chemical usage and incurred costs.
•We monitored dynamics of microbial communities along a SWRO desalination facility.•Microbial biofilm communities of RSF, CF, and RO differed from each other.•Biofilms from treatment pathway (CF) provided inocula for biofouling on RO membrane.•Conditions on RO restricted proliferation of RSF/CF biofilm's bacteria.•Site-specific microbial community characterization is required for biofilm treatment.
This study examined the abundance, cell size, and activity of Bacteria and Archaea in the Chukchi Sea and the Canada Basin of the western Arctic Ocean in the spring (May- June) and summer ...(July-August) of 2002 and 2004. Data from fluorescence in situ hybridization (FISH) analyses indicate that bacterial abundance as a percent of total prokaryotes decreased with depth, whereas in contrast, Crenarchaeota increased from about 10% of prokaryotes in surface waters to as much as 40% in samples from 100 to 200 m. Euryarchaeota were detectable in only a few samples. Relative abundance of Crenarchaeota, expressed as a percent of total prokaryotes, correlated with ammonium concentrations, but relative bacterial abundance did not. Crenarchaeota cells were significantly larger than Bacteria by 1.5- to 2-fold in the upper 200 m. Data collected from a combination of FISH and microautoradiography indicate that often the fraction of both Bacteria and Crenarchaeota assimilating organic compounds was high (up to 55%), and both microbial groups were more active in assimilating amino acids than other compounds. However, Crenarchaeota were usually less active than Bacteria in assimilating amino acids and glucose, but were nearly as active as Bacteria in assimilating protein and diatom extracellular polymers. The fraction of Bacteria and Crenarchaeota assimilating CO₂ in surface waters was higher than expected by anaplerotic fixation alone, suggesting that many of these microbes are chemoautotrophic. These data add to a growing body of evidence indicating how the roles of Archaea and Bacteria differ in biogeochemical cycles of the oceans.
Tata Element Modulatory Factor (TMF/ARA160) is a multifunctional Golgi-associated protein, which accumulates in colonic enterocytes and goblet cells. Mice lacking TMF/ARA160 (TMF ⁻/⁻) produce thick ...and uniform colonic mucus that resists adherent bacterial colonization and diminishes susceptibility of these mice to induced acute colitis, through a mechanism that is not fully understood. Here, we show that mucus secretion by goblet cells is altered in the colon of TMF ⁻/⁻ mice, resulting in the formation of a highly oligomerized colonic gel-forming mucin, MUC2. Microbiome analysis revealed a shift in the microbiota of TMF ⁻/⁻ mice leading to predominance of the Firmicutes phylum and a significantly higher abundance of probiotic beneficial bacterial species. Notably, this trait was transmissible, and when cohoused with wild-type animals, TMF ⁻/⁻ mice influenced the microbiota and diminished the susceptibility of wild-type mice to chemically induced dextran sulfate sodium colitis. Thus, altered mucus secretion in TMF ⁻/⁻ mouse colons is accompanied by a reprogrammed intestinal microbiota, leading to a transmissible reduced sensitivity to induced colitis.
We measured N2 fixation rates from oceanic zones that have traditionally been ignored as sources of biological N2 fixation; the aphotic, fully oxygenated, nitrate (NO(-) 3)-rich, waters of the ...oligotrophic Levantine Basin (LB) and the Gulf of Aqaba (GA). N2 fixation rates measured from pelagic aphotic waters to depths up to 720 m, during the mixed and stratified periods, ranged from 0.01 nmol N L(-1) d(-1) to 0.38 nmol N L(-1) d(-1). N2 fixation rates correlated significantly with bacterial productivity and heterotrophic diazotrophs were identified from aphotic as well as photic depths. Dissolved free amino acid amendments to whole water from the GA enhanced bacterial productivity by 2-3.5 fold and N2 fixation rates by ~2-fold in samples collected from aphotic depths while in amendments to water from photic depths bacterial productivity increased 2-6 fold while N2 fixation rates increased by a factor of 2 to 4 illustrating that both BP and heterotrophic N2 fixation were carbon limited. Experimental manipulations of aphotic waters from the LB demonstrated a significant positive correlation between transparent exopolymeric particle (TEP) concentrations and N2 fixation rates. This suggests that sinking organic material and high carbon (C): nitrogen (N) micro-environments (such as TEP-based aggregates or marine snow) could support high heterotrophic N2 fixation rates in oxygenated surface waters and in the aphotic zones. Indeed, our calculations show that aphotic N2 fixation accounted for 37 to 75% of the total daily integrated N2 fixation rates at both locations in the Mediterranean and Red Seas with rates equal or greater to those measured from the photic layers. Moreover, our results indicate that that while N2 fixation may be limited in the surface waters, aphotic, pelagic N2 fixation may contribute significantly to new N inputs in other oligotrophic basins, yet it is currently not included in regional or global N budgets.
Implementation of uranium bioremediation requires methods for monitoring the membership and activities of the subsurface microbial communities that are responsible for reduction of soluble U(VI) to ...insoluble U(IV). Here, we report a proteomics-based approach for simultaneously documenting the strain membership and microbial physiology of the dominant Geobacter community members during in situ acetate amendment of the U-contaminated Rifle, CO, aquifer. Three planktonic Geobacter-dominated samples were obtained from two wells down-gradient of acetate addition. Over 2,500 proteins from each of these samples were identified by matching liquid chromatography-tandem mass spectrometry spectra to peptides predicted from seven isolate Geobacter genomes. Genome-specific peptides indicate early proliferation of multiple M21 and Geobacter bemidjiensis-like strains and later possible emergence of M21 and G. bemidjiensis-like strains more closely related to Geobacter lovleyi. Throughout biostimulation, the proteome is dominated by enzymes that convert acetate to acetyl-coenzyme A and pyruvate for central metabolism, while abundant peptides matching tricarboxylic acid cycle proteins and ATP synthase subunits were also detected, indicating the importance of energy generation during the period of rapid growth following the start of biostimulation. Evolving Geobacter strain composition may be linked to changes in protein abundance over the course of biostimulation and may reflect changes in metabolic functioning. Thus, metagenomics-independent community proteogenomics can be used to diagnose the status of the subsurface consortia upon which remediation biotechnology relies.
Members of the SAR11 clade often dominate the composition of marine microbial communities, yet their contribution to biomass production and the flux of dissolved organic matter (DOM) is unclear. In ...addition, little is known about the specific components of the DOM pool utilized by SAR11 bacteria. To better understand the role of SAR11 bacteria in the flux of DOM, we examined the assimilation of leucine (a measure of biomass production), as well as free amino acids, protein, and glucose, by SAR11 bacteria in the Northwest Atlantic Ocean. We found that when SAR11 bacteria were >25% of total prokaryotes, they accounted for about 30 to 50% of leucine incorporation, suggesting that SAR11 bacteria were major contributors to bacterial biomass production and the DOM flux. Specific growth rates of SAR11 bacteria either equaled or exceeded growth rates for the total prokaryotic community. In addition, SAR11 bacteria were typically responsible for a greater portion of amino acid assimilation (34 to 61%) and glucose assimilation (45 to 57%) than of protein assimilation (</=34%). These data suggest that SAR11 bacteria do not utilize various components of the DOM pool equally and may be more important to the flux of low-molecular-weight monomers than to that of high-molecular-weight polymers.
Specialized prokaryotes performing biological dinitrogen (N2) fixation ('diazotrophs') provide an important source of fixed nitrogen in oligotrophic marine ecosystems such as tropical and subtropical ...oceans. In these waters, cyanobacterial photosynthetic diazotrophs are well known to be abundant and active, yet the role and contribution of non-cyanobacterial diazotrophs are currently unclear. The latter are not photosynthetic (here called 'heterotrophic') and hence require external sources of organic matter to sustain N2 fixation. Here we added the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) to estimate the N2 fixation potential of heterotrophic diazotrophs as compared to autotrophic ones. Additionally, we explored the influence of dissolved organic matter (DOM) on these diazotrophs along a coast to open ocean gradient in the surface waters of a subtropical coral lagoon (New Caledonia). Total N2 fixation (samples not amended with DCMU) ranged from 0.66 to 1.32 nmol N L-1 d-1. The addition of DCMU reduced N2 fixation by >90%, suggesting that the contribution of heterotrophic diazotrophs to overall N2 fixation activity was minor in this environment. Higher contribution of heterotrophic diazotrophs occurred in stations closer to the shore and coincided with the decreasing lability of DOM, as shown by various colored DOM and fluorescent DOM (CDOM and FDOM) indices. This suggests that heterotrophic N2 fixation is favored when labile DOM compounds are available. We tested the response of diazotrophs (in terms of nifH gene expression and bulk N2 fixation rates) upon the addition of a mix of carbohydrates ('DOC' treatment), amino acids ('DON' treatment), and phosphonates and phosphomonesters ('DOP' treatment). While nifH expression increased significantly in Trichodesmium exposed to the DOC treatment, bulk N2 fixation rates increased significantly only in the DOP treatment. The lack of nifH expression by gammaproteobacteria, in any of the DOM addition treatments applied, questions the contribution of non-cyanobacterial diazotrophs to fixed nitrogen inputs in the New Caledonian lagoon. While the metabolism and ecology of heterotrophic diazotrophs is currently elusive, a deeper understanding of their ecology and relationship with DOM is needed in the light of increased DOM inputs in coastal zones due to anthropogenic pressure.
The recognition of the microbiota complexity and their role in the evolution of their host is leading to the popularization of the holobiont concept. However, the coral holobiont (host and its ...microbiota) is still enigmatic and unclear. Here, we explore the complex relations between different holobiont members of a mesophotic coral
. We subjected two lines of the coral-with photosymbionts, and without photosymbionts (apo-symbiotic)-to increasing temperatures and to antibiotics. The different symbiotic states were characterized using transcriptomics, microbiology and physiology techniques. The bacterial community's composition is dominated by bacteroidetes, alphaproteobacteria, and gammaproteobacteria, but is dependent upon the symbiont state, colony, temperature treatment, and antibiotic exposure. Overall, the most important parameter determining the response was whether the coral was a symbiont/apo-symbiotic, while the colony and bacterial composition were secondary factors. Enrichment Gene Ontology analysis of coral host's differentially expressed genes demonstrated the cellular differences between symbiotic and apo-symbiotic samples. Our results demonstrate the significance of each component of the holobiont consortium and imply a coherent link between them, which dramatically impacts the molecular and cellular processes of the coral host, which possibly affect its fitness, particularly under environmental stress.
Abstract
The formation of biofilms and biofouling is a common feature in aquatic environments. The aim of this study was to identify the primary colonizers of biofilm formed in Eastern Mediterranean ...Coastal water at different seasons and follow early dynamics of biofilm community development. Pre-treated coastal seawater and biofilm samples were collected from six different sampling events of 2 weeks' duration each during 1 year. The microbial community composition and specific abundance were estimated by 16S rRNA gene clone libraries and fluorescence in situ hybridization–confocal laser scanning microscopy (FISH-CLSM), respectively. The biofilm formed over the course of the year was fairly consistent in terms of community composition and overall abundance with the exception of spring season. Alphaproteobacteria (30–70% of total bacteria), in particular Rhodobacteraceae, were the dominant bacteria in the biofilm, regardless of season, followed by Bacteroidetes (5–35%) and Gammaproteobacteria (6–35%). There was a decrease in relative abundance of Alphaproteobacteria and an increase in the abundance of Bacteroidetes between the initial and 2-week-old biofilm. This observation may aid man-made facilities that have to deal with biofilm formation and help the development of appropriate strategies to control those biofilms.
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