National Academy of Agricultural Sciences (NAAS)
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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
Soil salinity limits crop productivity, and salt-tolerant plant growth-promoting bacteria (PGPB) are promising candidates for biofertilizer development in saline soils. This study aimed to isolate bacteria from solar salterns at two sites, Wadala (Mumbai) and Mira-Bhayandar (Mumbai Metropolitan Region), and screen them in vitro for selected plant growth-promoting (PGP) traits. Sampling of salt-pan sediment, salt from salt mounds and brine water yielded nine stable isolates on high-salt Abram and Gibbons medium (AGM): A1, D, E, F and N from Wadala, and I1, I2, K and M from Mira-Bhayandar. All nine isolates grew at every NaCl concentration tested (0–25% w/v), although growth was visibly reduced at 25% NaCl. The isolates were screened for growth on nitrogen-free Ashby’s agar as an indicator of putative nitrogen fixation, siderophore production on chrome azurol S agar, ammonia production using Nessler’s reagent, and protease activity on milk agar. Each assay was performed in duplicate at 3% (w/v) NaCl, and mean values were reported. Eight isolates grew on nitrogen-free Ashby’s agar and were considered putative diazotrophs, while seven produced siderophore halos of 12–24 mm. All nine isolates produced ammonia, with corrected absorbance values at 425 nm ranging from 1.2 to 3.1, and exhibited protease activity, with clear zone-to-colony size (CZ/CS) ratios of 1.50–3.00. A composite score was calculated by normalising each quantitative trait to the highest observed value and averaging the three normalised values. Isolate F, recovered from Wadala salt-pan sediment, recorded the highest score (0.96), followed by the next-highest score of 0.71. Its 16S rRNA gene sequence showed the closest match to Halobacillus trueperi (98.52% sequence identity; GenBank accession PQ128859.1; strain designation vesasc). The findings highlight the solar salterns of Wadala and Mira-Bhayandar as sources of salt-tolerant bacteria exhibiting multiple in vitro PGP-related traits. In particular, isolate F emerged as a promising candidate for further evaluation of its plant growth-promoting potential under saline conditions.
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