Isolation and identification of potassium-solubilizing bacteria from Mikania micrantha rhizospheric soil and their effect on M. micrantha plants

Abstract

Potassium is directly involved in plant cell turgor-driven cell elongation, this is important for promoting the expansion of invasive plants. Soil potassium-solubilizing microorganisms in some invaded ecosystems may promote plant invasion by increasing potassium availability. The aims of this study were to isolate and identify potassium-solubilizing bacteria and to evaluate their contribution to the solubilization of potassium from potassium-feldspar, and to the potassium uptake of Mikania micrantha. Potassium-solubilizing bacteria were isolated using solid Aleksandrov medium in abandoned orchards that have been highly invaded by M. micrantha for more than 10 years. Our results revealed that 18 strains of efficient bacteria were identified using liquid Aleksandrov medium. Among the isolates, the Burkholderia genus had the highest solubilizing ability (1.75 mg L−1). The results of the pot culture experiment showed that the plant biomass and potassium content of M. micrantha with potassium-solubilizing bacteria were higher than in the control without these bacteria. Incubation with potassium-solubilizing bacteria, especially GZ18, significantly increased the plant phosphorus content. More potassium was solubilized in treatments with potassium-solubilizing bacteria than in the control without bacteria. These results strongly suggest that potassium-solubilizing bacteria in the rhizosphere of M. micrantha could improve potassium solubilization and uptake, and contributed to their success as an invasive species.