酱油腐败菌的分离鉴定与性质研究

Separation, Identification, and Characterization of Food Spoilage Bacteria in Soy Sauce

摘要:

乳酸菌和肠杆菌在传统食品的发酵中易引起食品腐败。本研究从传统酱醅和胀罐酱油中分离筛选到3株疑似腐败菌，对其进行形态、生理生化特性研究及16S rDNA序列分析，结合PCR-RFLP、ERIC-PCR及Species-Specific PCR，最终分别鉴定为产气肠杆菌、屎肠球菌（从酱醅中分离到）和马里乳杆菌（从胀罐酱油中分离到）。研究表明，产气肠杆菌具有极强产气性、而马里乳杆菌也具微弱产气性；将这三株菌接种到成品酱油中发现，均能微弱改变酱油pH值；同时这三株菌均对温度、pH、盐度具有耐受性；产气肠杆菌和屎肠球菌为条件致病菌，对消费者存在潜在危害，同时本研究发现马里乳杆菌的存在会引起酱油胀气、降低pH，从而导致酱油腐败。这三株菌的分离鉴定，对酱油的质量保证和食用安全性具有重要意义。

Abstract:

Lactic acid bacteria (LAB) and Enterobacter species commonly cause spoilage in traditional fermented foods. In this study, three bacterial strains suspected to cause food spoilage were isolated from traditional Chinese grain soy sauce and swollen canned soy sauce. The morphological and physiochemical characteristics and 16S rRNA sequences of the strains were studied. Using PCR-restriction fragment length polymorphism (PCR-RFLP), enterobacterial intergenic consensus–PCR (ERIC-PCR), and species-specific PCR, these strains were identified as Enterobacter aerogenes, Enterococcus faecium (isolated from grain soy sauce), and Lactobacillus acidipiscis (isolated from swollen canned soy sauce). The results showed that E. aerogenes possessed very strong gas-producing abilities, and L. acidipiscis was also a weak gas-producer. When the three bacterial strains were inoculated into soy sauce products, slight changes in the pH values of products were observed. In addition, all of the isolates were temperature-, pH-, and salinity tolerant. Both E. aerogenes and E. faecium are opportunistic pathogens and are potentially harmful to consumers. Furthermore, the presence of L acidipiscis in soy sauce could cause gas production and a reduction in pH, thus resulting in spoilage. The separation and identification of three bacterial strains were important to ensure adequate quality and food safety of soy sauce.