Characterization of Bacillus sp. LG from Yuncheng Salt Lake and its antimicrobial activity against Staphylococcus aureus

Abstract:

[Objective] A halotolerant bacterium LG was isolated from Yuncheng Salt Lake, and its identification and antimicrobial properties were studied. [Methods] The strain LG was identified by 16S rRNA gene sequence analysis. Using Staphylococcus aureus as the indicator, antimicrobial activity of the fermentation broth of strain LG was detected by cylinder plate method. Morphological and ultrastructure changes of treated cells were observed by scanning electron microscopy and transmission electron microscopy. Different physicochemical factors on its activity and PCR screening of functional genes were also studied. [Results] The strain is a halotolerant bacterium which can grow well over a range of NaCl concentration of 0-25%, and it is characterized as the genus of Bacillus and named as Bacillus sp. LG. Electron spectroscopy showed that significant morphological and ultrastructure changes of Staphylococcus aureus were observed after treatment by fermentation broth of Bacillus sp. LG. Antimicrobial properties of the strain LG indicated that it showed excellent stability towards temperature, ultraviolet, pH and NaCl. Using specific primers, polyketide synthase (PKS I) and nonribosomal peptide synthetase (NRPS) genes were detected by PCR technique, which indicated that the strain LG possess potential of producing active metabolites. [Conclusion] Results from the present study showed that microorganisms from extremophilic environment may be developed as a potential new source of antimicrobial substances.