Study on phosphate solubilizing ability of some bacterial isolates and determination of solubilized phosphorus fractionation in supernatant and microbial biomass

Phosphate solubilizing bacteria play roles in phosphate solubilizing from mineral sources. These bacteria with different mechanisms make it soluble, some parts of solubilized P were absorbed in their biomass and the other parts, released in the soluble form which can be used by other organisms.
In this study, 24 bacterial isolates belonged to different genera such as Azotobacter, Pseudomonas, Rhizobium, Beijerinckia, Klebsiella, Agrobacterium, Alcaligenes, Sphingomnas, Microbacterium and Citrobacter were examined to determine solubilized P from two sources of phosphate (TCP and RP) in Sperber medium. This research was carried out in a complementary random design with three replications. At the end of incubation time, solubilized P in supernatant, amount of P in biomass and total solubilized P were measured.
The results showed that isolates are efficient in solubilizing P from TCP than RP. By decreasing pH, solubilized P was increased (r=0.775, pDiscussion and In most researches, solubilized P which is present in supernatant takes more attention but phosphorus in biomass is ignored which can be mineralized and available with a delay. This study showed that most parts of solubilized P were measured in microbial biomass. Hence, attention to this criterion could help us to select efficient PSB.