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

从人体肠道分离出的含有乳酸菌的发酵乳的摄入可能对人体健康有益，因为这种细菌生活在胃肠道中，并具有益生菌的生理功能。细菌素是主要针对相关细菌物种的抗菌肽，这些成分可能在防止有害细菌在人体肠道中生长方面发挥重要作用。利用化学和基因克隆技术对从人体肠道分离的加色乳杆菌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N端和C端结合的环状细菌。从同一人肠道中分离到的另一株来自reuri乳杆菌LA6(Reuricin 6)的细菌素与Gassericin A具有相同的环状结构。两种细菌素对同一参照菌的作用方式略有不同。这可能是由于立体结构上的微小差异造成的。从人体肠道分离的加瑟氏乳杆菌SBT2055产生两种细菌素。第一个细菌素与乳杆菌F在结构上高度同源，第二个细菌素的序列尚不清楚。加瑟氏乳杆菌SBT2055在牛奶中的生长较差，但与酸奶的主要菌株嗜热链球菌共培养，促进了加瑟氏乳杆菌在牛奶中的生长，并产生了良好的细菌素。这表明用这种方法生产含细菌素的益生菌酸奶是可行的。

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.