Anti-infective potential of marine actinobacteria against carbapenem resistant Klebsiella pneumoniae ATCC 13882

Isolation of actinobacteria from mangrove rhizosphere sediments has been investigated for their antimicrobial properties. Twenty eight actinobacterial strains were isolated from the rhizosphere sediments collected from Parangipettai, Tamil Nadu and Andaman mangrove ecosystems. Strain PPA12 from Parangipettai mangrove sediments, which showed promising antimicrobial activity in agar plug method, had been selected as potential strain. The PPA12 actinobacteria produced bioactive metabolite only by agar surface fermentation and not by submerged fermentation. The bioactive metabolite from the potent strain PPA12 that was produced by agar surface fermentation which was extracted using different solvents and the maximum extraction was with methanol. The minimum inhibitory concentration (MIC) of the methanol extract was found to be 125μg/ml against carbapenem resistant Klebsiella pneumoniae. Partial purification of the crude methanol extract was done by TLC and the bioautography showed that the active fractions with RF value of 0.288 and 0.55 have bioactivity. The physiochemical, molecular characterization and phylogenetic analysis of the potent strain showed that the actinobacteria PPA12 was found to be Streptomyces fumigatiscleroticus.