Isolation, Antibacterial Testing from Novel Marine Actinomycetes

Abstract

Chowdari Sruthi , Yugandar N. M

This work was aimed at identifying marine actinomycetes and testing for their antibacterial properties. Water and sediment samples were collected from 10 different coastal regions of Visakhapatnam city, Andhra Pradesh, India. Hence, there were 125 actinomycete isolates using starch casein agar medium. These isolates were tested for antibacterial activity against 6 control organisms (Bacillus cereus, B. subtilis, Staphylococcus aureas, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli using cross-streak method. Out of the 125 isolates, 15 were active against all test bacteria, 52 were active against some of the test bacteria and 58 were not active against any of the test bacteria. The most promising isolates were subjected to secondary screening via the well diffusion method. Several experiments were done in order to establish the best environmental factors that would enhance the production of the antibacterial metabolite such as incubation time, temperature, pH, volume of inoculum, and carbon/nitrogen sources. Among all the isolate tested, the isolate J4 yielded the highest zone of inhibition at the optimised concentration. In this study, the authors establish that marine actinomycetes from coastal sediments could be a rich source of new antibiotics.