Antagonistic activity against nosocomial clinical isolates withBacillus subtilis MZ-7

Antibacterial activities were detected in thirty-six bacteria from six soil samples. One strain designated as Mz-7 produced an inhibitory substance which was active against number of Gram-positive bacteria as well as clinical isolates obtained from a local hospital. Strain Mz-7 was identified asBacillus subtilis by 16S rRNA sequence analysis and standard biochemical tests. Maximum production was observed at mid of stationary phase slightly before sporulation took place. Optimum conditions for growth were standardised. The antibiotic product was purified by chloroform precipitation and detected by polyacrylamide gel electrophoresis and mass spectrometry. It has lipopeptide nature and did not lose its activity on treatment at different pH values, temperatures and enzymes. The pronounce activity against multidrug resistant clinical isolates and the favourable biochemical properties of this antibiotic from the newly isolate strain suggest a new and effective agent against resistance in pathogenic microbes.