Screening of marine bacteria of Pakistan coast for drug discovery potential

The use of microorganisms for biological purpose has become an effective alternative to control pathogens. A total of 100 bacteria were isolated from marine samples of Sindh and Baluchistan coast of Pakistan and screened for antibacterial activity. One strain CMG1066, identified as Pseudomonas aeruginosa, showed antibacterial activity, capable of inhibiting growth of clinical isolates such as methicillin resistant Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Serratia marcesence, Salmonella typhi, Shigella flexnerie, Enterococcus faecalis, Enterococcus faecium, Streptococcus group G, Clostridium perfringens, Clostridium sporogenes, as well as indigenous marine bacteria such as Shewanella putrifacians, Vibrio alginolyticus, Micrococcus luteus and Bacillus subtilis. The inhibitory activity was stable at temperatures of 80°, 90° and 100°C, but was partially inactivated at 121°C. Analysis of Pseudomonas aeruginosa established that antibacterial activity could be detected in an ethyl acetate fraction of the crude extract, and this suggests that the substance was not bound to cell surface. Microscopic examination of exponentially growing cells of S. aureus and B. subtilis treated with crude extract of P. aeruginosa showed some very interesting morphological changes.