Solubilization of insoluble inorganic phosphate compounds by attached and free living marine bacteria

ABSTRACT

Phosphorous [P] is a plant nutrient, which is rapidly made immobile and less available for plant use after addition to the soil as a soluble fertilizer. Phosphate solubilizing microoganisms are able to improve the P nutrient availability to plants and thus stimulate plant growth. Marine bacteria isolated from attached and free surfaces were screened for solubilization of insoluble phosphate compounds. Both types of bacteria, attached and free-living demonstrated diverse levels of phosphate solubilization activity under in vitro conditions. Colonies of marine bacteria produced clear haloes on solid medium incorporating insoluble phosphate compounds, but only when glucose was provided as the carbon source. In attached bacteria 30% bacterial strains solubilized zinc phosphate, 19% solubilized calcium tri phosphate whereas, 18% of free-living bacteria solubilized zinc phosphate and 12% solubilized calcium tri phosphate