Description:
Sulfur-oxidizing microorganisms regulate S biogeochemistry in soil ecosystems, affecting ecosystem productivity and food quality. Elemental sulfur (S0 ) supplies SO42- for plants after being oxidized by S-oxidizing microorganisms, and the oxidative process is affected by soil pH, organic C, water content, temperature etc. However, the role of the S-oxidizing microbial community in S0 oxidation in soil with different water contents is unclear. We examined the S0 oxidation rate and microbial abundance and community (16S rRNA for total bacteria, soxB for S-oxidizing bacteria, and ITS for fungi) in a silty loam soil and a sandy loam soil with different water contents (i.e., 20%, 40%, and 60% WHC). The oxidation rate was significantly increased by increases in water content in the sandy loam soil, but not in the silty loam soil. This may have been because the interaction between water content and texture affected the contact between S0 and S oxidizers. Furthermore, the sandy loam soil had a much higher oxidation rate than the silty loam soil with 40% and 60% WHC. The ratio of soxB to 16S rRNA abundance in the sandy loam soil was much higher than that in the silty loam soil, irrespective of water content. Most S-oxidizing bacteria in the soils belonged to unknown taxa (67.86%), Alphaproteobacteria (19.17%), and Betaproteobacteria (9.69%). The S-oxidizing bacterial community composition was shifted in both soils, yet the significant correlation between the community composition and the S0 oxidation rate was only observed in the sandy loam soil ( r = 0.7037, P = 0.001). This may be attributed to the abundant and diverse typical S-oxidizing bacteria and the unknown soxB -containing bacteria in the sandy loam soil. Our study suggests that both water content and S-oxidizing bacterial community could be limiting for S0 oxidation in dryland soils with different textures