Antimicrobial Activity of Marine Actinomycete, <em>Nocardiopsis</em> sp. VITSVK 5 (FJ973467)

The aim of the present study was to isolate and to indentify the actinomycetes having antagonistic activity.An actinomycetes strain isolated from marine sediment samples collected at the Puducherry coast of India,showed antibacterial activity against selected microbial pathogens. The nutritional requirements and culturalconditions for maximal growth and yield of secondary metabolites have been optimized under shake-flaskconditions. The growth and yield of secondary metabolites was maximal with the use of ISP 1 mediumsupplemented with sea water, pH 7.4, and incubation temperature of 28/ C, salt tolerance of 2% and incubationtime of 4-7 days. Based on morphological, biochemical, physiological and phylogenetic characterization, thestrain was identified as <em>Nocardiopsis</em> sp. VITSVK5 (FJ973467). The petroleum ether extract (1000 :g/ml)obtained from the isolate showed significant antibacterial activity against Gram negative bacteria- <em>Escherichiacoli</em> (20 mm), <em>Pseudomonas aeruginosa</em> (18 mm) and <em>Klebsiella pneumonia</em> (15 mm) and Gram positivebacteria- <em>Enterococcus faecalis</em> (20 mm), <em>Bacillus cereus</em> (13 mm) and <em>Staphylococcus aureus</em> (6 mm) whencompared with streptomycin (25 :g/disc). The ethyl acetate extract (1000 :g/ml) showed antifungal activityagainst <em>Aspergillus fumigatus</em> (23 mm), <em>Aspergillus flavus</em> (15 mm) and <em>Aspergillus niger</em> (12 mm) whencompared with amphotericin-B (25 :g/disc). The chloroform extract (1000 :g/ml) was very effective againstyeasts, <em>Candida cruzi</em> (18 mm), <em>Candida tropicans</em> (15 mm) and <em>Candida albicans</em> (14 mm) when comparedto streptomycin (25 :g/disc). In conclusion the isolated strain has broad spectrum of antagonistic activityagainst Gram positive and Gram negative bacteria and <em>Aspergillus</em> sp.