A new function of the biocontrol bacterium Lysobacter enzymogenes LE16 in the mineralization of soil organic phosphorus

Abstract

To evaluate the functions of a new biocontrol bacterium, Lysobacter enzymogenes LE16, in the mineralization of soil organic phosphorus (P) and in the stimulation of plant P uptake and plant growth. Liquid culture, soil incubation, and pot experiments were used to study phosphatase production, inorganic P release from lecithin and soil organic P compounds, and the P uptake and growth of lettuce seedlings induced by L. enzymogenes LE16. This bacterium hydrolyzed lecithin by the release of acid, neutral and alkaline phosphatases in culture solutions with a pH ranging from 4.0 to 10.0 at 12–36 °C. The hydrolysis reactions were unaffected by NH4+-N, NO3−-N or urea at equal N concentrations but were promoted by low inorganic P. Bacterial inoculation significantly decreased the organic P but increased the water-soluble P and Olsen P in the soil. Compared to the use of chemical fertilizers alone, the P uptake, biomass, and economic yield of lettuce increased by 16.41%, 11.58%, and 11.30%, respectively, with an increase in soil Olsen P in the L. enzymogenes LE16 plus chemical fertilizer treatment. Environmental adaptation and phosphatase production could be the mechanisms involved in soil P mineralization and plant pathogen suppression by L. enzymogenes LE16. This is the first demonstration of a new use of L. enzymogenes LE16 in agriculture beyond plant protection.