Application of immobilized cells of Pseudomonas putida strain MTCC 6842 in alginate to solubilize phosphate in culture medium and soil

Plant growth-promoting rhizobacteria (PGPR) with potential to solubilize insoluble forms of phosphate (P) have been developed as carrier-based inoculants for agriculture improvement (Rodrìguez and Fraga, 1999). Immobilization of bacterial cells on polymers especially alginate to develop inoculant formulations of PGPR has received considerable interest (Bashan, 1998; Trivedi et al., 2005). These formulations are known to promote the survival of bacteria, preserve the beneficial traits, and when applied protect the cells from various biotic and abiotic stresses. In the present study, P-solubilization efficiency of Pseudomonas putida immobilized in sodium alginate beads in conditions of repeated batch cultures was determined. The efficiency of growth promotion was evaluated through a bioassay using wheat as test plant.