关键词: 耐盐细菌, Bacillus, Candida albicans, 抗菌活性, 功能基因

Abstract: The goal of this work is to identify a halotolerant bacterium LAY isolated from Yuncheng Salt Lake and study its antimicrobial properties. The strain LAY was identified by 16S rRNA gene sequence analysis. Using Candida albicans as the indicator, the antimicrobial activity of the fermentation broth of strain LAY was detected by cylinder plate method, and meanwhile the effects of different factors on the activities were studied. Morphological and ultra-structural changes of treated cells were observed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM). PCR screening of functional genes were also carried out. The results of phylogenetic analysis indicated that it was a halotolerant bacterium, and characterized as the genus of Bacillus, and named as Bacillus sp. LAY. The observation by electron spectroscopy discovered that morphological and ultra-structural changes of C. albicans after treatment by fermentation broth of Bacillus sp. LAY were significant. Antimicrobial properties of the strain LAY indicated that the activity of fermentation broth was stable, and showed excellent tolerance towards temperature, pH, NaCl and ultraviolet. Using specific primers, a gene for polyketide synthase(PKS)was detected by PCR technique, indicating that the strain LAY possessed the potential of producing polyketide. In conclusion, results from the study showed that extremophiles from salt lake might be developed as a potential new source of antimicrobial active substances.

Key words: halotolerant bacteria, Bacillus, Candida albicans, antimicrobial activity, functional gene