Strain Klebsiella ZP-2 inoculation activating soil nutrient supply and altering soil phosphorus cycling

Purpose Phosphorus (P) plays an important role in enhancing plant yield. Phosphate-solubilizing bacteria (PSB) could enhance soil P availability. This study aimed to determine the effects of PSB inoculation on soil P fractions and bacterial community and reveal the comprehensive linkages among soil bacteria, P fractions, and nutrient contents. Materials and methods In this study, PSB, Klebsiella ZP-2, was inoculated into soil with four different inoculation rates (2%, 4%, 6%, and 8%, bacterial suspension/soil weight = v:w); soil phosphatase activity, P fractions, function gene, and 16S rRNA were detected to comprehensively assess the effects of strain ZP-4 on soil properties, P fractions, and bacterial community. Results and discussion Soil available P and N were significantly higher in the treatments with 4% and 6% inoculation rates than that in the control. Compared with control, the contents of soil inorganic P extracted by sodium hydroxide (NaOH-Pi), water (H2O-Pi), and sodium bicarbonate (NaHCO3-Pi) were significantly increased. However, inorganic P extracted by hydrochloric acid (HCl-Pi) and residual P (residual-P) contents were significantly decreased, especially in the 4% inoculation rates. The strain ZP-2 stimulated functional genes (phoC and phoD) and soil phosphatase activity to active soil P. Meanwhile, the bacterial community structures were also significantly changed following the strain ZP-2 inoculation. Conclusion The strain ZP-2 inoculation improved soil available N and P contents, stimulated phosphatase activity to accelerate P cycling, and altered soil bacterial community. The ZP-2 strain has the potential to be used as a biofertilizers to improve soil fertility.

Automated summary

This study reveals that inoculation of phosphate-solubilizing bacteria Klebsiella ZP-2 can improve soil available phosphorus and nitrogen contents, stimulate phosphatase activity to accelerate phosphorus cycling, and alter soil bacterial community.