Molecular characterization of actinomycetes isolated from Tuichang river and their biosynthetic potential


Actinomycetes are antibiotic producing gram positive bacteria widely distributed in nature including fresh water habitat. The study of fresh water actinomycetes especially from river is still in infancy and has been less explored. In this study, 20 Streptomyces sp. were isolated from Tuichang river and were screened for their antimicrobial potential. Antibiotic sensitivity pattern of the isolates against standard antibiotics was also observed. Eight isolates (n=8; 40%) showed significant antibacterial activity against at least two tested bacterial pathogens, while six isolates (n=6; 30%) showed antifungal potential against at least two tested fungal phytopathogens. All the isolates showed resistance to penicillin G and ampicillin. Of all the isolates screened, BPSWAC23 and BPSWAC24 inhibited all the tested fungal and bacterial pathogens and showed resistance to 50% of the antibiotics. BPSWAC23 and BPSWAC24 were identified by using 16S rRNA gene sequencing and found to be Streptomyces sp. Streptomyces parvus respectively. Further, biosynthetic genes coding for polyketide synthase (PKS II) and nonribosomal peptide synthetase (NRPS) were also detected in these two isolates which indicates a good candidate for the discovery of novel antibiotics.

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