Micrococcus endophyticus strain WH16 oxidizes elemental sulfur in sodic soil: Effect on soil properties and crop performance

Abstract

Micrococcus endophyticus is a heterotrophic, plant growth‐promoting endophyte that thrives within the inner tissues of various plants. This study presents the first report on the elemental sulfur (S°) oxidation potential of the M. endophyticus strain WH16, isolated from high sodic soils. The strain demonstrated significant phosphorus (P) and zinc (Zn) solubilization, as well as the production of indole‐3‐acetic acid, ammonia, and titratable acidity in the growth medium. It formed a biofilm around S° particles. The WH16 strain harbors the soxA , soxB , and soxC genes of 720, 590, and 329 base pairs, respectively, associated with the S° oxidation pathways. Application of WH16‐inoculated S° to sodic soils with pH ranging from 9.1 to 10.5 resulted in 13.0%–24.2% greater S° oxidation than the uninoculated control ( p < 0.05). The WH16 strain enhanced the concentration of Ca ^{2 +} , Mg ^{2 +} , and SO ₄ ^{2 −} , coupled with a decline in HCO ₃ ⁻ and total soil alkalinity in the soil solution. The integration of M. endophyticus strain WH16 with S° resulted in a 6.78%–29.5% increase in rice and wheat yields compared to soils treated with S° alone. These findings suggest that the bacterial isolate M. endophyticus strain WH16 is a promising plant growth‐promoting microbe for faster S°‐based sodic soil reclamation, with additional benefits for plant growth and productivity.