一株瑞士乳杆菌的分离鉴定及其产VB_(12)的影响因素研究

对市售的乳酸饮品的乳酸菌进行了分离纯化,得到菌株HYWZ-6,结合16S r RNA基因序列分析,确定为瑞士乳杆菌(Lactobacillus helveticus),并以温度、Na Cl、胆盐、p H及柠檬酸三钠作为影响因素,对其产VB_(12)进行研究,并利用酶联免疫分析法对该菌在不同因素条件下培养100 h后产VB_(12)的含量进行测定。结果表明,HYWZ-6菌株在不同条件下产VB_(12)的差异性较大,35℃VB_(12)的含量最高,25℃最低,35℃时含量比25℃时高出175.2%;Na Cl质量分数与VB_(12)的含量呈反比,Na Cl质量分数为1%时VB_(12)含量最高,7%时最低,相差224.4%;胆盐质量分数为0.1%时VB_(12)含量达到最高;p H为4时VB_(12)含量最高,在p H为7时VB_(12)含量最低,前者是后者的5.8倍;柠檬酸三钠质量分数为2.5%时VB_(12)的产量最高,比最低产量高出143.2%。

Isolation and Identification of a Lactobacillus helveticus and Research on the Effect Elements of VB12 Produced by It

A bacterial strain called HYWZ-6 was isolated and purified from lactic acid drink,being available in the market,combined with 16S rRNA sequence analysis,it was identified as Lactobacillus helveticus.The influencing factors of VB12 produced by HYWZ-6,such as temperature,NaCl,cholate,pH and trisodium citrate were studied,and the content of VB12 was measured by VB12 enzyme immunoassay afier the bacterial strains had been cultivated under different circumstances for 100 hours.The results showed that the bacterial strain HYWZ-6's situation on producing VB12 under different circumstances had relatively huge differences,the content of VB12 would reach maximum at the temperature of 35 ℃,and it would reach the minimum at the temperature of 25 ℃℃,the discrepancy was 175.2％.The concentration of NaCl was inverse proportion to the content of VB12.When NaCl was 1％,the content of VB12 would reach maximum;when the NaCl was 7％,it would reach the minimum,the discrepancy was 224.4％.The content of VB12 would reach the maximum when cholate was 0.1％.The content of VB12 would reach the maximum when pH was 4,and it would reach the minimum when pH was 7,the former was 5.8 times as much as the latter.The output of VB12 was most when the trisodium citrate was 2.5％,the discrepancy between the highest yield and the lowest yield was 143.2％.