Assessment of Soil Bacterial Community Structure Changes in Response to Hydrogen Gas Released by N2-fixing Nodules

Nucleic acid based technologies are useful tools in the investigation of microbial community composition. This study used three such methods – T-RFLP/PAT, clone library and metatranscriptome analyses – to probe changes in soil bacterial populations exposed to hydrogen gas. Total DNA and RNA were collected from both lab and greenhouse soil samples exposed to H2, with soil samples not treated with H2 used as controls. All three methods showed the same general trends, with members of Actinobacteria being suppressed by H2 exposure and populations of Proteobacteria, particularly β- and γ-proteobacteria, being stimulated by the presence of H2. These results agree with previous studies and show that all three techniques, either alone or in combination, are reliable methods for investigating shifts in soil microbial community composition when exposed to a selective pressure such as H2. This study also shows that H2has a marked effect on soil biology and microbial ecology. This soil bacterial community change explains the reported soil gas production switch and associated plant growth promotion.