Isolation, identification and ecological adaptability of phosphate-and potassium-solubilizing bacteria in maize rhizosphere.

[Objective] The phosphate-and potassium-solubilizing bacteria were isolated and identified from maize rhizosphere and their ecological adaptability was further analyzed in the present study, which provide excellent strains for enriching the microbial resources library and developing microbial fertilizers. [Method] The phosphate-solubilizing bacteria were isolated from maize rhizosphere by plate dilution method and identified by 16S rRNA gene sequence and homologous alignment. Subsequently, the strains with the strongest capability of phosphate solubilization were selected to analyze their potassium solubilization capability and ecological adaptability. [Result] A total of 9 strains of organic phosphate-solubilizing bacteria and 2 strains of inorganic phosphate-solubilizing bacteria were obtained from maize rhizosphere, and the concentrations of available phosphate were 0.018 to 4.479 mg/L and 5.383 to 6.242 mg/L, respectively. According to the phylogenetic tree, these strains were identified and affiliated to Pseudomonas, Bacillus, Cupriavidus, Leclercia and Enterobacter, respectively. The strain P4-5 with the strongest capability of organic phosphate solubilization was grouped into a clade with Pseudomonas frederiksbergensis, and strain CP4-1 2 with the strongest inorganic phosphate solubilization capacity was clustered a clade with Leclercia adecarboxylata. Strains P4-5 and CP4-12 dissolved potassium feldspar in the liquid medium and the corresponding available potassium concentrations were 8.100 mg/L and 1.333 mg/L, respectively. Strain P4-5 had a strong ability to resist salt, but could not tolerate strong acid and alkali, moderate drought and high concentrations of pesticides. Strain CP4-1 2 had strong salt, drought and pesticides resistance, while could not tolerate strong acid and alkali. [Conclusion] Two bacterial strains with phosphate and potassium solubilization capacity were isolated from maize rhizosphere with ability to resist acid, alkali, salt, drought and pesticides. This study provides excellent strain resources for the application of microbial fertilizers. [ABSTRACT FROM AUTHOR]