Kimoto Hiromi, Nomura Masaru, Kobayashi Miho, Mizumachi Koko, Okamoto Takashi
Department of Animal Products, National Institute of Livestock and Grassland Science, Tsukuba Norin-danchi, Ibaraki, Japan.
Can J Microbiol. 2003 Nov;49(11):707-11. doi: 10.1139/w03-092.
One of the important properties of probiotics is the ability to survive in the intestine. There have been few studies on the probiotic property of lactococci, since they are formally not considered to be natural inhabitants of the intestine. To evaluate lactococci as probiotic bacteria, we investigated their ability to survive during gastric transit by in vitro and in vivo tests. When exposed to an in vitro simulated gastrointestinal environment, such as low pH and bile, only Lactococcus lactis subsp. lactis bv. diacetylactis N7 showed a moderate survival rate among the four strains tested. The tested strains were orally administered to mice, and intestinal passage of the ingested strains was monitored by two methods: antibiotics and PCR. Viable cells of strain N7 were recovered from feces within 24-48 h after administration but not at 72 h. Lactococcus lactis subsp. cremoris ATCC 19257, which had a poor survival rate in vitro test, was also detected at 12 h but not at 24 h. These results indicate that lactococci can reach the mouse intestine alive, but not colonize it. If administered daily, viable strain N7 may exist continuously in the intestine. The effect of strain N7 on intestinal microbial balance and on animal health will be the subject of a further study.
益生菌的重要特性之一是在肠道内存活的能力。由于乳酸球菌通常不被认为是肠道的天然定植菌，因此关于乳酸球菌益生菌特性的研究较少。为了评估乳酸球菌作为益生菌的潜力，我们通过体外和体内试验研究了它们在胃转运过程中的存活能力。当暴露于体外模拟胃肠道环境（如低pH值和胆汁）时，在所测试的四株菌中，只有乳酸乳球菌乳酸亚种双乙酰乳酸变种N7表现出中等存活率。将测试菌株口服给予小鼠，并通过两种方法监测摄入菌株在肠道中的通过情况：抗生素法和PCR法。在给药后24 - 48小时内从粪便中回收了N7菌株的活细胞，但在72小时时未回收。在体外试验中存活率较低的乳酸乳球菌乳脂亚种ATCC 19257在12小时时也被检测到，但在24小时时未被检测到。这些结果表明，乳酸球菌可以存活到达小鼠肠道，但不能在其中定植。如果每天给药，活的N7菌株可能会在肠道中持续存在。N7菌株对肠道微生物平衡和动物健康的影响将是进一步研究的主题。
