›› 2015, Vol. 42 ›› Issue (4): 796-803.doi: 10.16431/j.cnki.1671-7236.2015.04.004

Previous Articles     Next Articles

Isolation and Identification of Shiga Toxin-producing Escherichia coli from Yak (Bos grunniens) in the Northwestern Sichuan,and Sequence Analysis of stx2 Gene

TONG Jing-jing, LIU Fei, ZHOU Fang, RAN Dan-dan, TANG Cheng   

  1. College of Life Science and Technology, Southwest University for Nationalities, Chengdu 610041, China
  • Received:2014-10-08 Online:2015-04-20 Published:2015-05-05

Abstract: In order to study the prevalence of yak meat Shiga toxin-producing Escherichia coli (STEC) in Northwestern Sichuan and its stx2 subtype, five suspected colonies were picked from each enrichment culture of 204 collected yak meat samples (25 g). Double PCR assay was used to detect stx1 and stx2, stx2 was subtyped and its CDS region was sequenced. 8 STEC strains were isolated from 204 samples, in which the isolating rate of STEC was 3.9% (8/204). 4 different serotypes O detected were O38(4), O50(1), O74(2) and O150(1), respectively. 6 strains were found carry stx2, and 2 strains were stx2a and 4 strains were stx2c. The results revealed that yak-original isolated strains had a high degree of amino acid homology with human-original and cattle-original strains; Amino acid phylogenetic trees of stx2 A and B subunits showed that yak-original, human-original and cattle-original strains gathered into the same clade, indicating that their genetic distance was relatively near. Yak-original stx2 were distributed in their own little branch, compared with the human-original and cattle-original strains, although yak-original STEC stx2 genetic relations were closer with them, but still had some differences.

Key words: Shiga toxin-producing Escherichia coli (STEC); Shiga toxin subtype; yak meat

CLC Number: