A marine strain HS-A38 with potent antimicrobial activity was isolated from the intestine of wild sea cucumber in Dalian sea area. Based on the analysis of morphological, physiological and 16S rDNA sequence, the strain HS-A38 was identified as Bacillus subtilis. Two bioactive substances (1 and 2) were purified from the fermented broth of the strain HS-A38 with the methods of fractional sedimentation with ammonium sulfate, CM-52 ion-exchange chromatography and Sephadex G-75 gel filtration. The SDS-PAGE analysis indicated that the relative molecular weight of both bioactive substances 1 and 2 were 41 kDa and 28 kDa, respectively. The antibacterial spectra showed that substance 1 could only inhibit Gram positive bacteria, whereas substance 2 could significantly inhibit both the Gram positive and negative bacteria.
Marine microorganisms, antibacterial activities, bioactive substance
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