Phosphorus Solubilization by Species.

Microbial solubilization applies the natural ability of a microorganism to liberate phosphorus from unavailable structures. The main mechanism recognized to be responsible for the solubilization of phosphorus is the production of different types of organic acids. Three kinds of species and three types of raw materials (poultry bones, fish bones, and ash) were tested for solubilization. The following parameters were compared for all discussed cases: pH, specific growth rate, solubilization factor, released phosphorus concentration, and total and individual concentration of organic acids. Utilization of ash brought about the highest specific and maximum specific growth rates. A decrease in pH was observed in most of the discussed cases with the exception of fish bones. At the same time, fish bones had the highest concentration of released P₂O₅ and the highest total concentration of produced organic acids (gluconic, lactic, acetic, succinic, and propionic) in all discussed cases. The tested species produced the mentioned acids with the exception of , where propionic acid was not present. The lactic and acetic acids were those produced in the highest amount. The kind of raw materials and type of species used in solubilization had a strong influence on the kind of organic acids that were detected in the broth culture and its total concentration, which had a direct influence on the amount of released phosphorus. The combination of with the fish bones at 5 g/L is proposed as the pair that gives the highest concentration of released phosphorus (483 ± 5 mg/L).