Effect of H₂ on soil bacterial community structure and soil denitrifier population

Abstract

Previous studies have shown that H₂ from HUPˉ legume nodules promotes plant growth and enhances N₂O emission from soil, possibly as the result of hydrogen-induced variation of rhizobacterial community structure. Using terminal restriction fragment length polymorphism and 16S rRNA clone library, the current study revealed that the major bacterial groups that responded to H₂ exposure belong to Gammaproteobacteria and Bacteroidetes . To understand the relationship between H₂ exposure and soil denitrification, the gene copy number of a key gene in the denitrification process, nirK , encoding copper nitrite reductase, was quantified in soil samples with different treatments using a real-time PCR technique. The result showed that the nirK gene copy numbers in soil increased significant after H₂ treatment. Several key genes in the denitrification pathway (such as qnorB, nosZ ) were confirmed in some soil H₂-oxidizing bacterial isolates suggesting a connection between H₂ uptake and N₂O emission.