Dipartimento di Biologia Strutturale e Funzionale, Università Federico II, via Cinthia 4, complesso MSA, 80126 Napoli, Italy.
Res Microbiol. 2009 Dec;160(10):817-23. doi: 10.1016/j.resmic.2009.09.009. Epub 2009 Sep 24.
In order to perform selective isolation of bacteria tightly bound to the human gut, ileal biopsies of healthy volunteers were treated to wash out the mucus layer and loosely bound bacterial cells. Rod-shaped anaerobic bacteria that had remained attached to the epithelial cells were isolated and identified at the species level. One isolate was identified as belonging to the Bifidobacterium breve species, while all the others were lactobacilli of only two species, Lactobacillus mucosae and Lactobacillus gasseri. Members of these species were found previously in intestinal samples, but their predominance among bacteria strictly associated with the epithelium was not suspected before and suggests that these species may represent a specific subpopulation of tissue-bound bacteria. Physiological analysis indicated that all isolates were able to produce antimicrobials, grow and form biofilm in simulated intestinal fluid after exposure to gastric conditions. Some isolates were able to degrade mucin while none showed cytotoxicity in vitro on HT29 cells. The tight association of the strains isolated with ileal epithelial cells is presumably indicative of a direct interaction with the host cells. For this reason and for the absence of cytotoxicity in vitro, those isolates can be proposed as potential probiotic strains for human use.
为了对紧密结合人体肠道的细菌进行选择性分离，我们对健康志愿者的回肠活检组织进行处理，以冲洗掉黏液层和松散结合的细菌细胞。然后分离并鉴定出仍附着在上皮细胞上的杆状厌氧菌。其中一个分离株被鉴定为短双歧杆菌，而其他所有分离株均为两种乳杆菌，即黏着性乳杆菌和加氏乳杆菌。这些物种的成员以前在肠道样本中被发现，但在与上皮细胞紧密相关的细菌中它们占据优势地位，这在以前是没有被怀疑的，这表明这些物种可能代表了组织结合细菌的一个特定亚群。生理分析表明，所有分离株在暴露于胃条件后均能够在模拟肠液中产生抗生素、生长并形成生物膜。一些分离株能够降解黏蛋白，但没有一种分离株在体外对 HT29 细胞显示出细胞毒性。分离株与回肠上皮细胞的紧密关联推测表明它们与宿主细胞之间存在直接相互作用。由于这些分离株在体外没有细胞毒性，因此可以将其作为潜在的益生菌菌株用于人体。
