Bacterial Diversity in Replicated Hydrogen Sulfide-Rich Streams

Area of Science:

• Microbial ecology
• Biogeography
• Environmental microbiology

Background:

• Extreme environments shape microbial communities, but the role of non-temperature stressors like toxicants is understudied.
• Understanding microbial biogeography in toxicant-influenced habitats is crucial for predicting ecosystem responses.
• Hydrogen sulfide (H2S) is a common toxicant in various environments, yet its specific impact on microbial communities needs further investigation.

Purpose of the Study:

• To investigate the influence of elevated hydrogen sulfide (H2S) on microbial diversity and community composition in a paired stream system.
• To compare the effects of H2S on bacteria with previous findings for macroinvertebrates and fish in the same habitats.
• To identify core bacterial taxa associated with H2S-rich environments and explore potential symbiotic relationships.

Main Methods:

• Sampling of water from paired streams with high (>20 μM) and low (~0 μM) H2S concentrations.
• Sequencing of the 16S rRNA gene to analyze bacterial diversity and community composition.
• Statistical analysis to determine the effect of H2S on bacterial diversity and community structure, and comparison with macroinvertebrate and fish data.

Main Results:

• Elevated H2S did not significantly affect overall bacterial diversity (p=0.21).
• H2S strongly influenced bacterial community composition, explaining 25.8% of the variation (p<0.0001).
• Nine abundant operational taxonomic units (OTUs) formed a core H2S-rich stream microbiome, with Epsilonproteobacteria and Gammaproteobacteria being prominent.

Conclusions:

• Hydrogen sulfide is a significant driver of bacterial community composition, despite not altering overall diversity.
• The identified core microbiome in H2S-rich streams suggests specialized adaptations.
• The prevalence of sulfur-oxidizing bacterial groups indicates potential for undiscovered symbiotic relationships in these extreme environments.