SCREENING OF PHOSPHATE SOLUBILIZING BACTERIA FOR PLANT GROWTH PROMOTING FACTOR FROM RHIZOSPHERIC SOIL

Phosphorus is essential for the growth and productivity of plant which can absorb phosphate only in soluble form. The phosphate solubilizing bacteria (PSB) mobilize insoluble phosphate into soluble form through enzymatic and organic acid production. Thus, PSB can be used as biofertilizers and are able to improve the soil fertility. The phosphorous is most abundant in soil both in organic as well as inorganic form and is the major limiting factor for the growth of the plant. In the present study, 6 phosphate solubilizing bacteria were isolated from various agricultural fields and designated as NR1-NR6. NR-1, NR-2 and NR-5 were found to be strong phosphate Solubilizer, with halo zone diameters of 13, 12 and 12 mm respectively on Pikovskaya agar. All the isolates were further screened for plant growth promoting factor such as siderophore, HCN, ammonia and cell wall degradation enzyme production. All the isolates were found to be positive for siderophore production and their frequency ranged from 5mm -11 mm. NR-1, NR-3, NR-4 and NR-5 were positive for HCN production. NR-1, NR-2, NR-3 and NR-5 produced ammonia. While isolates NR-1, NR-2, NR-4 and NR-6 produced cellulase and protease which are cell wall degrading enzymes. All the isolates were also characterized in term of morphological and biochemical test and after comparison with the Bergy’s Manual of Systematic Bacteriology the isolates NR-1, NR-2, NR-3 and NR-5 tentatively assigned as Pseudomonas spp. while NR-4 and NR-6 assigned as Bacillus spp.