Vol. 7, Issue 9, Part G (2025)

Phosphate solubilizing bacteria (PSB) serve as eco friendly biofertilizers by converting insoluble soil phosphorus—often bound with aluminum, iron, calcium, or magnesium—into plant available forms. They achieve this by secreting low molecular weight organic acids that chelate metal ions, thus releasing phosphate ions for uptake. In a survey of soils from Satara and Sangli districts in Western Maharashtra, forty two samples yielded ten PSB isolates selected based on phosphate solubilization index (SI ranging 1.00-4.08) and solubilization efficiency (PSE up to 308%). When cultured in Pikovskaya’s broth containing tricalcium phosphate (TCP), phosphate release ranged from 52.7 to 180.5 mg/L, with isolate Tas 1 achieving the highest (180.5 mg/L). Morphological, cultural, and biochemical tests identified six isolates (Pal 1, Pal 2, Tas 1, Is 1, Pat 2, Ane 1) as Bacillus spp., and four (Kde 1, Wa 2, Sat 1, Kr 1) as Pseudomonas spp. All isolates tested positive for catalase, oxidase, and citrate utilization; several showed bromothymol blue reaction, ammonia production, and motility. Five isolates exceeded 100 mg/L phosphate solubilization, highlighting Tas 1 as a highly promising candidate for agricultural biofertilizer development.