Mangrove ecosystems harbor diverse microbial communities that play crucial roles in nutrient cycling and ecosystem sustainability. Phosphorus is an essential macronutrient for plant growth; however, a large proportion of soil phosphorus exists in insoluble forms that are unavailable for plant uptake. Phosphate-solubilizing bacteria (PSB) enhance phosphorus availability by converting insoluble phosphate into plant-accessible forms. This study investigated the prevalence and phosphate-solubilizing potential of bacteria associated with the rhizospheric soil of selected mangrove species in the Muthupet Mangrove Reserve, Tamil Nadu, India. A total of 45 soil samples were collected from five mangrove sites at three different depths and analyzed for physicochemical characteristics, including soil pH and texture. Soil pH ranged from 7.0 to 8.3, indicating neutral to moderately alkaline conditions. Soil texture analysis revealed that Sample 2 was well-graded (Cu = 14.84; Cc = 1.64), whereas the remaining samples were poorly graded. Isolation on Pikovskaya’s agar medium yielded 167 phosphate-solubilizing bacterial isolates, of which 112 pure cultures were obtained and 38 isolates were selected for further screening. Three isolates (O1, O2, and O3) exhibited superior phosphate-solubilization activity with phosphate solubilization index (PSI) values of 2.67 ± 0.21, 2.63 ± 0.25, and 2.47 ± 0.31, respectively. Morphological and biochemical characterization revealed that all three isolates were Gram-positive bacteria with distinct physiological traits. The findings demonstrate the abundance of efficient native PSB in mangrove sediments and highlight their potential application as eco-friendly bio-inoculants for sustainable agriculture and improved phosphorus management.
