Bioprospecting potential of fast growing endophytic bacteria from leaves of mangrove and salt-marsh plant species

In the present study, bioprospecting aspects of endophytic bacteria, isolated from leaves of 5 mangroves and 2 salt-marsh plant species, were explored. In total, 104 bacterial isolates were isolated from the leaf samples of mangrove plants of Pichavaram, Tamil Nadu. Thirty six fast growing isolates were selected and screened for biological activities. Of 36 isolates, 28 (77%) showed antimicrobial activity, and 94.4% of isolates exhibited pectinase, 58.3% protease and 52.7% inulinase and invertase activities. Plant growth promoting activity, such as, ammonia and acetoin production, was shown by 22 (61.1%) and 25 (69.4%) endophyte isolates, respectively; whereas 26 isolates (72.2%) showed nitrogen fixing activity. Six isolates (16.6%) showed phosphate solubilization activity and 7 isolates (19.4%) produced indole acetic acid (IAA). Further, malachite green and phenol degrading activities were observed in 12 (33.3%) and 20 (55.5%) endophytic bacterial isolates, respectively. More than 20 endophytic bacteria were sensitive to antibiotics like streptomycin and trimethoprim, while 31 isolates (86.1%) were resistant to vancomycin and bacitracin. Thirty four (94.4%) and 31 (86.6%) endophytic isolates exhibited growth onto a medium containing upto 7.5 and 10% NaCl concentrations, respectively. The present study has proved that the mangroves are the sources of endophytic bacteria with bioprospecting potential, which deserves further studies.