Organic electron donors and terminal electron acceptors structure anaerobic microbial communities and interactions in a permanently stratified sulfidic lake

Abstract

The extent to which nutrients structure microbial communities in permanently stratified lakes is not well understood. This study characterized microbial communities from the anoxic layers of the meromictic and sulfidic Fayetteville Green Lake (FGL), NY, and investigated the roles of organic electron donors and terminal electron acceptors in shaping microbial community structure and interactions. Bacterial communities from the permanently stratified layer below the chemocline (monimolimnion) and from enrichment cultures inoculated by lake sediments were analyzed using 16S rRNA gene sequencing. Results showed that anoxygenic phototrophs dominated microbial communities in the upper monimolimnion (21 m), which harbored little diversity, whereas the most diverse communities resided at the bottom of the lake (~52 m). Organic electron donors explained 54% of the variation in the microbial community structure in aphotic cultures enriched on an array of organic electron donors and different inorganic electron acceptors. Electron acceptors only explained 10% of the variation, but were stronger drivers of community assembly in enrichment cultures supplemented with acetate or butyrate compared to the cultures amended by chitin, lignin or cellulose. We identified a range of habitat generalists and habitat specialists in both the water column and enrichment samples using Levins index. Network analyses of interactions among microbial groups revealed Chlorobi and sulfate reducers as central to microbial interactions in the upper monimolimnion, while Syntrophaceae and other fermenting organisms were more important in the lower monimolimnion. The presence of photosynthetic microbes and communities that degrade chitin and cellulose much below the chemocline supported the downward transport of microbes, organic matter and oxidants from the surface and the chemocline. Collectively, our data suggest niche partitioning of bacterial communities by interactions that depend on the availability of different organic electron donors and terminal electron acceptors. Thus, light, as well as the diversity and availability of chemical resources drive community structure and function in FGL, and likely in other stratified, meromictic lakes.

Top‐down enrichment of oil field microbiomes to limit souring and control oil composition during extraction operations

“…We found that each well had a distinct microbial composition with various sulfur‐reducing (or H 2 S‐producing) bacteria as well as other archaea and bacteria found in previous MEOR studies 17,41 . Common bacteria phyla include Proteobacteria, Bacteroidota, Firmicutes, Synergistota, Spirochaetota, Verrucomicrobiota, Desulfobacterota, and Campilobacterota, of which the latter three are prominent sulfur‐metabolizing bacteria 42–45 . These populations were distinct from others in the literature, 13,37 a finding that is not unexpected given that each community is driven by un environmental conditions such as temperature, salinity, pH, nutrient availability, and oil gravity among other factors 25 .…”

“…17,41 Common bacteria phyla include Proteobacteria, Bacteroidota, Firmicutes, Synergistota, Spirochaetota, Verrucomicrobiota, Desulfobacterota, and Campilobacterota, of which the latter three are prominent sulfur-metabolizing bacteria. [42][43][44][45] These populations were distinct from others in the literature, 13,37 a finding that is not unexpected given that each community is driven by un environmental conditions such as temperature, salinity, pH, nutrient availability, and oil gravity among other factors. 25 However, there is no known correlation between native microbial community and MEOR success.…”

“…17,25,41 The increasing pressure and drop in pH imply that the production of some or all of these was stimulated by nutrient supplementation. However, production of H 2 S by Campylobacteria, such as Sulfurospirillium and Malaciobacter, 43,47 may have also been stimulated. While our results indicated at least two responsive wells for MEOR intervention, successful MEOR biostimulation requires limited production of corrosive H 2 S while also increasing the gas, acid, and/or solvent production for oil recovery.…”

A re‐examination of the mechanism of whiting events: A new role for diatoms in Fayetteville Green Lake (New York, USA)

“…2, S2). This interpretation is supported by the fact that microorganisms degrading chitin have been described in the FGL monimolimion (Rojas et al, 2021).…”

Methane-related community of a carbonate-enriched pockmark, Brazilian Southeastern continental slope

“…They were recently also characterized as polysulfide reducers (Flieder et al, 2021), the distribution of which was reported to be driven by grain size and Cu and Cr concentrations in a high hydrocarbon-contaminated marine sediment in the Mediterranean Sea (Dell'Anno et al, 2021). The same positive correlation to methane detection with Chloroflexi and Elusimicrobiota indicates that these groups could be similarly involved in anaerobic hydrocarbon degradation via fermentation (Bovio-Winkler, Cabezas and Etchebehere, 2021), giving meaning to some groups included in the "microbial dark matter" found in anaerobic sulfidic systems, such as Elusimicrobiota (Rojas et al, 2021).…”