奶粉中凝结芽孢杆菌的分离鉴定及其耐受性研究

Isolation,identification and stress resistance of Bacillus coagulans from milk powder

为探究凝结芽孢杆菌体外耐受性,以奶粉为样品来源,通过80℃加热、分离纯化鉴定获得凝结芽孢杆菌12株,对其进行耐酸、耐高温和耐胆盐试验。结果表明,W3、W25、W80和W55分离株在pH2.0的酸性环境中存活率较高;W55、W10、W25和W80分离株在高温环境中存活率较高;W55、W48和W68分离株在0.5%和1.0%胆盐质量分数中的存活率较高。将抗逆性较好的W55分离株进行了酸性条件下的高温挑战试验,分离株在pH4.0,加热温度90℃时存活率最高,但其存活率低于单因素下(酸性或高温环境)的存活率(P <0.05)。挑战试验结果表明,酸性条件和高温会相互影响凝结芽孢杆菌的耐受性。试验为后续凝结芽孢杆菌发酵饮料的研制提供了理论依据和基础。

In this study,twelve Bacillus coagulans strains were isolated from milk powder by heating at 80 ℃,separation,purification and identification to investigate their stress resistance in vitro.The results showed that isolates W3,W25,W80,and W55 had higher survival rates under acidic environments at pH 2. 0. In addition,isolates W55,W10,W25 and W80 had higher survival rates under high-temperature environments and isolates W55,W48,and W68 had higher survival rates under0. 5% and 1. 0% of bile salt (mass fraction). Thus,isolate W55 with better stress resistance was subjected to high temperature challenge tests under acidic conditions. The results showed that isolate W55 had the highest survival rate at pH 4. 0 and heating temperature of 90 ℃,but its survival rate was lower than that under a single factor (acidic or high temperature environment) (P < 0. 05). Challenge test results showed that acidic conditions and high temperatures can produce interaction for the stress resistance of B. coagulans. These tests provided a theoretical basis for the subsequent development of fermented beverages of B. coagulans.