Associated effect of soybean meal and native microbial community on the accelerated arsenite oxidation by Achromobacter xylosoxidans YYS001 in paddy soil

Arsenite [As(III)]-oxidizing bacterium in paddy soil could oxidize As(III) to arsenate [As(V)], but the effect of the native microbial community and organic matter on its As(III)-oxidizing capacity and the translocation of arsenic species was poorly understood. In this study, Achromobacter xylosoxidans YYS001 with high As(III)-oxidizing ability was isolated from Zijinshan mining area in Longyan, China, a fourteen day greenhouse cultivation experiment and a pot experiment over the whole rice growth period were conducted to evaluate how the inoculation ratio of strain YYS001, the native microbial community and organic matter influenced the strain YYS001-mediated As(III) oxidation and the subsequent accumulation and translocation of As species from soil to rice grains. The results from the fourteen-day greenhouse cultivation experiment showed that the native microbial community and soybean meal briefly promoted the As(III) oxidation by strain YYS001, the results from the whole rice growth period showed that strain YYS001 significantly increased the relative abundance of plant growth-promoting (PGP) bacteria such as Streptomyces , Dyella , and Sphingomonas in the rhizosphere microbial community of the indica rice cultivar LuYouMingZhan, increased rice yield per plant by 100.5% (Control yield = 8.74 g/plant, YYS001 yield = 17.52 g/plant, p < 0.05), and decreased the concentration of inorganic arsenic (iAs) by 26.6% in rice grains (Control iAs = 0.15 mg/kg, YYS001 iAs = 0.11 mg/kg, p < 0.05). Soybean meal promoted the methylation of iAs in the rhizosphere soil of indica LuYouMingZhan. Further, it decreased the iAs concentration by 40.5% (Control iAs = 0.15 mg/kg, YYS001 + OM iAs = 0.09 mg/kg, p < 0.05) through increasing the Dimethylarsinic acid concentration in rice grains. This research elucidated the effect of soil environment on the bacterial As(III) oxidation ability and provided the basis for their application in rice fields.