Biogeographic congruency among bacterial communities from terrestrial sulfidic springs

Abstract

Terrestrial sulfidic springs support diverse microbial communities by serving as stable conduits for geochemically diverse and nutrient-rich subsurface waters. Microorganisms that colonize terrestrial springs likely originate from groundwater, but may also be sourced from the surface. As such, the biogeographic distribution of microbial communities inhabiting sulfidic springs should be controlled by a combination of spring geochemistry and surface and subsurface transport mechanisms, and not necessarily geographic proximity to other springs. We examined the bacterial diversity of seven springs to test the hypothesis that occurrence of taxonomically similar microbes, important to the sulfur cycle, at each spring is controlled by geochemistry. Complementary Sanger sequencing and 454 pyrosequencing of 16S rRNA genes retrieved five proteobacterial classes, and Bacteroidetes, Chlorobi, Chloroflexi, and Firmicutes phyla from all springs, which suggested the potential for a core sulfidic spring microbiome. Among the putative sulfide-oxidizing groups (Epsilonproteobacteria and Gammaproteobacteria), up to 83% of the sequences from geochemically similar springs clustered together. Abundant populations of Hydrogenimonas-like or Sulfurovum-like spp. (Epsilonproteobacteria) occurred with abundant Thiothrix and Thiofaba spp. (Gammaproteobacteria), but Arcobacter-like and Sulfurimonas spp. (Epsilonproteobacteria) occurred with less abundant gammaproteobacterial populations. These distribution patterns confirmed that geochemistry rather than biogeography regulates bacterial dominance at each spring. Potential biogeographic controls were related to paleogeologic sedimentation patterns that could control long-term microbial transport mechanisms that link surface and subsurface environments. Knowing the composition of a core sulfidic spring microbial community could provide a way to monitor diversity changes if a system is threatened by anthropogenic processes or climate change.

Thermophilic bacterial communities inhabiting the microbial mats of “indifferent” and chalybeate (iron‐rich) thermal springs: Diversity and biotechnological analysis

“…The higher number of OTUs obtained for the metagenome of Calitzdorp microbial mat could be due to the increase in complexity of the thermophilic communities with increases in levels of some physicochemical parameters like temperature, DO, TDS, and total Fe in CA as compared to BV. The rarefaction curves (Figure ) revealed that the diversity of microbes could be even more complex than witnessed, and similar findings were reported in other microbial mats including hypersaline mat (Abed et al., ), geothermal mat (Coman et al., ) and hydrothermal vent microbial mat (Headd & Engel, ).…”

“…Shannon index at 0.03 5.7 6.4 F I G U R E 3 Rarefaction curves using 0.03 dissimilarity cut-off levels; BV-Brandvlei microbial mat and CA-Calitzdorp microbial mat be even more complex than witnessed, and similar findings were reported in other microbial mats including hypersaline mat (Abed et al, 2015), geothermal mat (Coman et al, 2013) and hydrothermal vent microbial mat (Headd & Engel, 2014).…”

“…Within this phylum, the most abundant class was Gammaproteobacteria (21.64%) followed by Betaproteobacteria (6.68%), other classes which occurred in low percentages included Alphaproteobacteria (0.38%), Deltaproteobacteria (0.15%), and Epsilonproteobacteria (0.34%) (Table S1). Some previous studies have demonstrated that Epsilonproteobacteria is dominant in microbial habitats associated with sulfidic springs (45°C) and hydrothermal vent (> 100°C), and plays a role in carbon and sulfur cycling (Headd & Engel, ). Compared to CA, the BV mat sample was comprised of Gammaproteobacteria (5.9%), Betaproteobacteria (1.35%), Alphaproteobacteria (0.55%), and Deltaproteobacteria (0.16%) while Epsilonproteobacteria was not recorded (Table S1).…”

“…Epsilonproteobacteria is dominant in microbial habitats associated with sulfidic springs (45°C) and hydrothermal vent (> 100°C), and plays a role in carbon and sulfur cycling (Headd & Engel, 2014). Compared to CA, the BV mat sample was comprised of Gammaproteobacteria (5.9%), Betaproteobacteria (1.35%), Alphaproteobacteria (0.55%), and…”

Minimization of biomethane oxygen concentration during biogas upgrading in algal–bacterial photobioreactors

“…The detection of bacteria from the Alphaproteobacteria class (bands 6 and 7), which are normally found in nitrification-denitrification processes, correlated with the intense nitrification activity observed along the entire experimentation. The presence of SO 4 2 in the cultivation medium mediated by H 2 S oxidation supported the identification of cyanobacteria (bands 9-13) previously found in terrestrial sulfidic springs [44]. Interestingly, despite the above mentioned low CH 4 solubilization in the recycling cultivation broth, methane oxidizing bacteria belonging to the genus Methylosarcina (band 4) were identified in the 4 operational stages [45].…”