环糊精葡萄糖基转移酶工业发酵染菌(Bacillus cohnii strain PGRS7)的鉴定及防治

Classification and Prevention of Industrial Fermentation Contaminant(Bacillus cohnii strain PGRS7)on Cyclodextrin Glycosyltransferase

环糊精生产厂家β-环糊精葡萄糖基转移酶(β-cyclodextrin glycosyltransferase,β-CGTase)发酵过程中频繁染菌,为解决这一问题,从发酵异常的发酵液中分离得到1株不产酶的杂菌H03S。研究杂菌发酵过程中的菌体密度、pH值、酶活等指标,发现杂菌生长速度明显低于正常菌,发酵液pH值下降速度也慢于正常菌。结合厂家实际生产情况分析:若发酵过程规范操作,则正常菌会优先形成生长优势,抑制杂菌生长;如果发酵罐实消后放置时间过长或者突发停电导致发酵终止后重新启动,杂菌会形成优势菌群,降低发酵液pH值,不利于正常菌的增殖。16S rDNA鉴定杂菌序列与正常菌不同,应归属于Bacillus cohnii strain PGRS7。因此,发酵前应预先采用16S rDNA分析鉴定菌种,排除杂菌,避免发酵中断和延迟,防止发酵染菌。

Bacteria contamination occurs frequently during the fermentation ofβ-cyclodextrin glycosyltransferase(β-CGTase)in production factories.To solve this problem,the authors isolated a sundry bacterial strain H03S from aberrant fermentation broth ofβ-CGTase that did not produce the enzyme.The bacteria OD,pH value and enzyme activity of H03S in fermentation process were studied.It was found that the growth rate and pH of H03S was significantly lower than that of the normal bacteria.Analysis combined with the actual production situation,if the fermentation process was under normal operation,the normal bacteria will primarily form growth dominance and inhibit the growth of sundry bacteria,however,if the fermentation tank were placed for a long time after sterilization or the fermentation were restarted after a period of termination due to sudden power failure,H03S might form dominant population and reduce the pH of fermentation broth,and make against the proliferation of normal strain.16S rDNA identification of H03S was knowable that it was different from normal strain in sequence and it should belong to Bacillus cohnii strain PGRS7.Therefore,before starting the fermentation,analysis and identification of production strain could anticipate adopting 16S rDNA to preclude the contamination of sundry strain,at the same time,avoid the abort and retardation of the fermentation,to prevent the fermentation of sundry strain.