双歧杆菌（有时作为“益生菌”用在酸奶和其他食物产品中）是人肠道中的天然细菌，已知能保护我们不发生感染。现在，关于这种保护作用的至少一部分的一个可能机制已以醋酸盐的形式被发现。让小鼠口服“长双歧杆菌”的一个亚型，似乎能保护它们不被有潜在致命性的大肠杆菌O157:H7感染，因为它能促进上皮细胞中的宿主防卫机制。（生物谷Bioon.com）

生物谷推荐原文出处：

Nature doi:10.1038/nature09646

Bifidobacteria can protect from enteropathogenic infection through production of acetate

Shinji Fukuda,Hidehiro Toh,Koji Hase,Kenshiro Oshima,Yumiko Nakanishi,Kazutoshi Yoshimura,Toru Tobe,Julie M. Clarke,David L. Topping,Tohru Suzuki,Todd D. Taylor,Kikuji Itoh,Jun Kikuchi,Hidetoshi Morita,Masahira Hattori& Hiroshi Ohno

The human gut is colonized with a wide variety of microorganisms, including species, such as those belonging to the bacterial genus Bifidobacterium, that have beneficial effects on human physiology and pathology1, 2, 3. Among the most distinctive benefits of bifidobacteria are modulation of host defence responses and protection against infectious diseases4, 5, 6. Nevertheless, the molecular mechanisms underlying these effects have barely been elucidated. To investigate these mechanisms, we used mice associated with certain bifidobacterial strains and a simplified model of lethal infection with enterohaemorrhagic Escherichia coli O157:H7, together with an integrated ‘omics’ approach. Here we show that genes encoding an ATP-binding-cassette-type carbohydrate transporter present in certain bifidobacteria contribute to protecting mice against death induced by E. coli O157:H7. We found that this effect can be attributed, at least in part, to increased production of acetate and that translocation of the E. coli O157:H7 Shiga toxin from the gut lumen to the blood was inhibited. We propose that acetate produced by protective bifidobacteria improves intestinal defence mediated by epithelial cells and thereby protects the host against lethal infection.