Early plant growth promotion of maize by various sulfur oxidizing bacteria that uses different thiosulfate oxidation pathway

Abstract

The objective of the work was to evaluate the plant growth promotion of maize by thiosulfate-oxidizing bacteria possessing the tetrathionate intermediate (S4I) and/or paracoccus sulfur oxidation (PSO) pathway for thiosulfate oxidation. Halothiobacillus sp. possessing the S4I and PSO pathways for thiosulfate oxidation recorded the highest phosphate solubilization (480 µg ml-1), followed by other S4I pathway bearing bacteria (Microbacterium phyllosphaerae and Pandoraea sputorum). All the tested bacterial strains such as Halothiobacillus sp., Dyella thiooxydans, M. phyllosphaerae, Pandoraea sputorum, and Pandoraea sp., consumed the glucose and thiosulfate simultaneously, indicating that these organisms had a mixotrophic metabolism. Results of growth chamber study revealed that inoculation of D. thiooxydans and M. phyllosphaerae (both holding the S4I pathway) significantly enhanced the maize root length (73 and 67%, respectively), shoot length (27 and 31%), and shoot biomass (58 and 45%), along with the nutrient uptake of P, K, S, Mn, Ca, Cu and Na. Therefore, it was concluded that D. thiooxydans and M. phyllosphaerae possessing the S4I pathway are effective early plant growth promoting rhizobacteria for maize when compared with other bacteria possessing the S4I and PSO pathway for thiosulfate oxidation.