Effect and mechanism of the tnaA gene on probiotic EcN prevention of colitis in mice

This study investigated the role and mechanism of tnaA gene on Escherichia coli Nissle 1917, named EcN, in the prevention of colitis in mice. This study focused on the differences in indole secretion, biofilm, and inhibition of AIEC between the tnaA gene deletion and complementary strains of the pre constructed EcN bacteria and the wild strain of EcN, and explored the mechanism. Subsequently, we compared the preventive effects of WT and tnaA deleted strains of EcN on DSS induced colitis in mice and the differences in regulation of intestinal flora by pre gavage of bacteria. The final experimental results showed that the tnaA deleted strain secreted less indole, formed less biofilm, and was less motile, but had an enhanced inhibitory effect on pathogenic bacteria; gavage of both WT and tnaA deleted strains was effective in preventing colitis in mice, and pregavage of the tnaA deleted strain increased the abundance of the beneficial intestinal bacteria Lactobacillus reuteri, Akkermansia muciniphila, and Bacteroides acidifaciens.

本研究探究了命名为EcN的大肠杆菌Nissle 1917（Escherichia coli Nissle 1917）中tnaA基因在小鼠结肠炎预防中的作用与机制。本研究聚焦于预先构建的EcN菌株的tnaA基因敲除株、互补株与野生型EcN菌株在吲哚分泌、生物膜形成以及对黏附侵袭性大肠杆菌（AIEC）抑制作用方面的差异，并对其调控机制进行了深入探究。随后，本研究对比了EcN野生型菌株与tnaA基因敲除株对葡聚糖硫酸钠（DSS）诱导的小鼠结肠炎的预防效果，以及预先灌胃菌株对肠道菌群的调控差异。最终实验结果表明，tnaA基因敲除株的吲哚分泌量更低、生物膜形成能力更弱且运动能力下降，但对致病菌的抑制作用显著增强；灌胃野生型菌株与tnaA基因敲除株均可有效预防小鼠结肠炎，且预先灌胃tnaA基因敲除株可显著提升肠道有益菌罗伊乳杆菌（Lactobacillus reuteri）、嗜黏蛋白阿克曼菌（Akkermansia muciniphila）和解酸拟杆菌（Bacteroides acidifaciens）的丰度。