动物造模 Z-bio 2023-02-15 529

　　Objective To evaluate the colonization ability and efficiency of two Escherichia coli engineering strains, Nissle1917 and BW25113, in the intestinal tract by using mice, so as to screen out the strains with high colonization efficiency in the intestinal tract, and lay a foundation for the subsequent research on the use of clustered regularly spaced short palindrome repeat sequences and related protein systems of engineering bacteria to reduce the drug resistant bacteria in vivo.

　　Methods A total of 70 ICR mice of 18-20 g were selected from each strain of engineering bacteria, half male and half female. During the operation, the mice were divided into 7 treatment groups randomly, 10 in each group (6 experiments, 4 controls). Experimental group: gavage 2 × A total of 1010 engineering bacteria were 200 µ L, and the control group was given the same volume of PBS by gavage. At 1, 3, 6, 12, 24, 48 and 72 hours after gavage, the mesenteric lymph nodes, stomach, ileocecal and colon tissues and contents of mice were taken respectively, and the engineering bacteria were detected by plate scribing, fluorescence microscopy and PCR methods respectively, to compare the colonization ability and efficiency of the two strains of Nissle1917 and BW25113 in mice.

　　Results In the first six periods (1,3,6,12,24,48 h) after gavage, two strains of bacteria were detected in stomach, ileocecal and colon tissues by three methods, and no target strains were detected in lymph nodes; However, at 72 h, only Nissle1917 was colonized in ileocecal and colon tissues. The colonization efficiency of Nissle1917 and BW25113 were 100% and 0, respectively.

　　Conclusion The colonization efficiency of Nissle1917 is higher than that of BW25113, and it can colonize the ileocecal and colon tissues for a long time, suggesting that it can be used as an alternative carrier for the CRISPR system for the prevention and control of drug resistance gene transmission.