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Mangrove forests occurring at the interface of terrestrial and marine ecosystems represent a rich biological diversity of plants, animals and microorganisms. Microbes, being an important component of the mangrove environment, not only play a very critical role in creating and maintaining this biosphere but also serve as a source of biotechnologically valuable and important products. By participating in various steps of decomposition and mineralization of leaf litter, microbes make an essential contribution to the productivity of the mangrove ecosystem. They able to recycle nutrients, produce and consume gases that affect global climate, destroy pollutants, treat anthropogenic wastes and can also be used for biological control of plant and animal pests. Microorganisms from mangrove environments are a major source of antimicrobial agents and also produce a wide range of important medicinal compounds, including enzymes, antitumor agents, insecticides, vitamins, immunosuppressants, and immune modulators. However, the phylogenetic and functional description of microbial diversity in mangrove ecosystems has not been addressed to the same extent as for other environments. Even though the mangrove ecosystem is very rich in microbial diversity, less than 5% of species have been described; in many cases neither their ecological role nor their application potential is known. Recently developed technologies in molecular biology and genetics offer great promise to explore the potential of microbial diversity. Hence, the present paper makes an attempt to review the microbial diversity in mangrove ecosystems and explore their potential applications in various fields such as agriculture, pharmaceutical, industrial, environmental and medical sciences.

Phosphorus is an essential element for all life forms. Phosphate solubilizing bacteria are capable of converting phosphate into a bioavailable form through solubilization and mineralization processes. Hence in the present study a phosphate solubilizing bacterium, PSB-37, was isolated from mangrove soil of the Mahanadi river delta using NBRIP-agar and NBRIP-BPB broth containing tricalcium phosphate as the phosphate source. Based on phenotypic and molecular characterization, the strain was identified as Serratia sp. The maximum phosphate solubilizing activity of the strain was determined to be 44.84 μg/ml, accompanied by a decrease in pH of the growth medium from 7.0 to 3.15. During phosphate solubilization, various organic acids, such as malic acid (237 mg/l), lactic acid (599.5 mg/l) and acetic acid (5.0 mg/l) were also detected in the broth culture through HPLC analysis. Acid phosphatase activity was determined by performing p-nitrophenyl phosphate assay (pNPP) of the bacterial broth culture. Optimum acid phosphatase activity was observed at 48 h of incubation (76.808 U/ml), temperature of 45 °C (77.87 U/ml), an agitation rate of 100 rpm (80.40 U/ml), pH 5.0 (80.66 U/ml) and with glucose as a original carbon source (80.6 U/ml) and ammonium sulphate as a original nitrogen source (80.92 U/ml). Characterization of the partially purified acid phosphatase showed maximum activity at pH 5.0 (85.6 U/ml), temperature of 45 °C (97.87 U/ml) and substrate concentration of 2.5 mg/ml (92.7 U/ml). Hence the present phosphate solubilizing and acid phosphatase production activity of the bacterium may have probable use for future industrial, agricultural and biotechnological application.

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