襄阳孔明菜卤水中耐盐污染菌的分离与鉴定

Isolation and identification of salt-tolerant contamination strain from brine of the turnip of Xiangyang

襄阳孔明菜是在高盐下腌制的一种腌菜,在大规模露天腌制过程中,由于雨水污染等原因会在卤水表面长白色菌膜,导致孔明菜的软化,影响口感.从襄阳孔明菜卤水污染物中分离污染菌并进行鉴定,旨在对防控该污染菌奠定基础.将污染菌膜接种于不同浓度梯度氯化钠的YPD固体培养基上,分别在28℃与37℃培养3d后,从28℃分离到一种耐盐酵母,单菌落呈圆形、乳白色,3d培养直径为0.1～0.2cm,表面湿润、粘稠、易挑起.对该菌的进一步研究显示,该菌可以在含有0%～15%NaCl的YPD培养基中生长,最适生长盐浓度为5%;最适生长温度为28℃,可以在pH值5.5～6.5之间生长,最适生长pH值为6.0.抽提该菌的总DNA,扩增部分18SrDNA片段,测序后进行同源比对,结果显示,该耐盐酵母的18SrDNA序列和Zygosaccharomyces rouxii DoNor8、IFO0510、M2的18SrDNA序列一致性达到100%,根据clustal X和MEGA4.1建构的系统进化树进行分析,该酵母与Z.rouxii在同一分支上,再结合形态和生理特征,认定分离的嗜盐酵母是Zygosaccharomyces rouxii.该菌的分离和鉴定为研究腌制食品中污染菌的防控有一定意义.

The turnip of Xiangyang is a kind of pickle made in high-salt. Because of rain pollution, the brine surface will form white pellicle, leading to the turnip soften and affecting the palate. This research focused on isolating and identifying the contaminant strain from the contaminative brine of the turnip of Xiangyang so as that the prevention and control of contamination could be realized. The pollution pellicles were innoculated on YPD solid culture medium including different concentration of sodium chloride, respectively, then cultured in 28 ℃ and 37 ℃ for three days. A kind of salt-tolerant yeast was isolated from 28 ℃ culture. The single colony of isolated strain was circular, white, the surface wetting, ropy and easy to provoke and diameter of single colony was 0. 1-0.2 cm after three days culture. The further research showed that this yeast could grow in the YPD medium containing 0 %-15% of NaC1, optimum growth salt concentration was 5 %; pH growth range was 5.5-6.5 and the optimum growth pH was 6.0; the optimum growth temperature was 28 ~C. The total DNA of this yeast was also extracted and part of 18SrDNA fragment was amplified and sequenced. The sequence was analyzed by Blast program. The result showed that 18SrDNA of this salt-tolerant yeast had 100% identity with 18SrDNA of Zygosaccharomyces roua-ii DoNorS, IFO0510 and M2. According to the system evolutionary tree constructed by clustal X and MEGA4. 1, the yeast and Z. roua＇ii were in the same branch. In combination with morphological and physiological characteristics, the isolated salt-tolerant yeast was identified as isolation and identification of this yeast has some significance contamination in pickled food. Zygosaccharomyces rouxii. in the prevention and control of characteristics, the isolated salt-tolerant yeast was identified as Zygosaccharomyces rouxii. The isolation and identification of this yeast has some significance in the prevention and control of contamination in pickled food.