Chemical and molecular biological studies on the bacteriocins produced by probiotic lactic acid bacteria.

摄入含有从人体肠道中分离出的乳酸菌的发酵乳可能对人体健康产生有益影响，因为这种细菌在胃肠道中生存并具有益生菌的生理功能。细菌素是主要作用于相关细菌种类的抗菌肽，这些成分可能对防止人体肠道中有害细菌的生长很重要。通过化学和基因克隆技术，对从人肠道中分离的加氏乳杆菌 LA39 产生的细菌素进行了化学序列分析。细菌素（Gassericin A）是一种新发现的环状细菌，其N端和C端结合。从同一人体肠道中分离的罗伊氏乳杆菌LA6（Reutericin 6）产生的另一种细菌素被发现具有与Gassericin A相同的环状结构。两种细菌素对相同参考细菌的作用方式略有不同。这是由于空间结构可能存在细微差异。其他从人肠道中分离的 L.gasseri SBT2055 产生两种细菌素。第一种与Lactacin F结构高度同源。第二种细菌素的序列仍不清楚。 L.gasseri SBT2055 在牛奶中的生长较差，但与用于酸奶制作的主要菌株嗜热链球菌共培养，加速了 L.gasseri 在牛奶中的生长，同时产生令人满意的细菌素。这表明通过这种方式生产含有细菌素的益生菌酸奶变得可行。

The intake of fermented milk containing lactic acid bacteria isolated from human intestine may have beneficial effects on human health, as the bacteria survive in the gastrointestinal tract and have physiological functions as probiotics.Bacteriocins are antimicrobial peptides that act mainly against related bacterial species, and these components may be important in preventing the growth of harmful bacteria in the human intestine. Bacteriocin produced from Lactobacillus gasseri LA39 that was isolated from human intestine was analyzed with chemical sequence by chemical and gene cloning technique. The bacteriocin (Gassericin A) was a newly found cyclic bacteria which was bound at the N-and C-terminal ends.Another bacteriocin produced from Lactobacillus reuteri LA6 (Reutericin 6) isolated from the same human intestine was revealed to have same cyclic structure as Gassericin A.The slight difference was observed in the mode of action between two bacteriocins against the same reference bacteria. This is due to possibly slight differences in the steric structure. Other L.gasseri SBT2055 isolated from human intestine produced two kinds of bacteriocins. The first was the highly homologous in structure with Lactacin F.The sequences of the second bacteriocin is still unclear. Growth of L.gasseri SBT2055 in milk is poor but co-culture with Streptococcus thermophilus, the major strain used for yogurt making, accerelated the growth of L.gasseri in milk accompanying satisfactory production of bacteriocin. This suggests that the production of probiotic yogurt containing bacteriocin becomes feasible by this way.