Quantitative assessment of zinc solubilizing bacteria isolated from soils of western Maharashtra

The research was carried out at laboratory of plant pathology and Agricultural Microbiology, College of Agriculture, Pune. In the present investigation, efficient zinc solubilizing bacteria isolated from rhizospheric soils of Sangli and Satara districts of Western Maharashtra. Out of 45 samples, 9 bacterial isolates were obtained. A total of nine bacterial isolates were tested, with pH recorded on the day of inoculation and subsequently at 5, 10 and 15 days after inoculation (DAI). All isolates exhibited a gradual decline in pH over time, indicating acid production. Among the isolates, Pal-3 demonstrated the most significant drop in pH (from 7.00 to 2.99) followed by Sat-3 and Kar-2, highlighting their potential effectiveness in solubilizing zinc. Those 9 isolates were tested for their capacity to solubilize zinc in vitro and soluble Zn content (mg/L) was measured on the 7th and 10th days of incubation. Results revealed significant differences among isolates, with Pal-3 recording the highest zinc solubilization (65 mg/L on the 7th day and 87 mg/L on the 10th day) followed by Bor-1 and Pha-5. Based on the findings, isolates Pal-3, Bor-1 and Pha-5 emerged as the most efficient zinc solubilizers.