Inorganic phosphate solubilization by two insect pathogenic Bacillus sp

Abstract

Two strains (Bacillus thuringiensis (kurstaki) and Bacillus sphaericus) having ability to solubilize inorganic phosphates were screened from the local isolates tested to control lepidopteran pests. In the phosphate solu-bilization and pH reduction properties investigated, both were found to solubilize phosphate in both Sperber's medium and Pikovskaya's medium. In plate assays B. thuringiensis (kurstaki) showed very poor solubilization in Sperber's medium and B. sphaericus did not show any sign of solubilization in both the media used. However, in broth cultures, maximum phosphate solubilization was seen in Pikovskaya's medium than Sperber's medium. P-solubilization was found to be associated with pH reduction.