Isolation and screening of bioactive principle from Chaetomorpha antennina against certain bacterial strains.

Microbial pathogens develop resistance to a particular antibiotic after repeated administration during the treatment of infectious diseases. Moreover, multiple drug resistance is a very common problem especially in hospital acquired infections. Therefore, it is necessary to find out alternative antibacterial drugs and the present trend is focused on seaweeds. This preliminary research work was carried out to find out the antibacterial activity of petroleum ether extract of Chaetomorpha antennina. The extracts were tested against Staphylococcus aureus MTCC 121, Bacillus cereus MTCC 492, Bacillus subtilis MTCC 441, Klebsiella pneumoniae MTCC 530, Escherichia coli MTCC 443 and Pseudomonas aeruginosa MTCC 779 by agar well diffusion technique. It was observed that petroleum ether extract showed prominent zone of inhibition against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus even at 50 µg/ml concentration. The maximum spectrum of activity was observed against Staphylococcus aureus ranged from 7.3 ± 0.8 to 18 ± 2.4 mm at the concentration 50 to 500 µg/ml, respectively. Hence the most susceptible bacterium was Staphylococcus aureus among the tested organisms. However, Escherichia coli and Pseudomonas aeruginosa are also susceptible. But the Bacillus cereus and Klebsiella pneumoniae are resistant against the tested extract.