Postgraduate Program in Food, Nutrition and Metabolism (PPGNAM), Federal University of Mato Grosso (UFMT), Cuiabá, Mato Grosso 78060-900, Brazil.
Postgraduate program in Food Science (PPGCAL), Chemistry Institute, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro 21941-909, Brazil.
J Appl Microbiol. 2023 Jan 23;134(1). doi: 10.1093/jambio/lxac027.
Characterize Escherichia coli and E. coli -producing (STEC) isolates from Brazilian beef to determine heat resistance and the presence of the transmissible locus of stress tolerance (tLST).
Twenty-two STEC previously isolated from beef and characterized as STEC by PCR were subjected to different heat survival challenges (60°C and 71°C). Furthermore, the three tLST-positive isolates and one tLST-negative isolate by PCR were selected for WGS analysis. Phenotypic results indicated that 3/22 (13.64%) were heat resistant, 12/22 (54.54%) were moderately resistant, and 7/22 (31.82%) were sensitive to heat treatments. WGS analyses showed that three isolates with heat resistance showed tLST with up to 80% and 42% of similarity by BLAST analysis, with the major tLST genes being responsible for the homeostasis module. However, WGS showed the absence of stx genes associated with tLST-positive isolates, albeit with virulence and resistance genes found in extraintestinal pathogenic E. coli (ExPEC).
Our findings demonstrate the presence of heat-resistant E. coli as well as confirm some tLST genes in E. coli isolated from Brazilian beef.
对巴西牛肉中分离出的大肠杆菌和产志贺毒素大肠杆菌（STEC）进行分析，以确定其耐热性和可传播应激耐受基因座（tLST）的存在情况。
对 22 株先前从牛肉中分离并通过 PCR 鉴定为 STEC 的 STEC 进行了不同的耐热性生存挑战（60°C 和 71°C）。此外，还选择了 3 个 tLST 阳性和 1 个 tLST 阴性的 PCR 阳性分离株进行 WGS 分析。表型结果表明，3/22（13.64%）具有耐热性，12/22（54.54%）中度耐热，7/22（31.82%）对热处理敏感。WGS 分析显示，3 株耐热分离株的 tLST 与 BLAST 分析的相似度高达 80%和 42%，主要 tLST 基因负责体内平衡模块。然而，WGS 显示与 tLST 阳性分离株相关的 stx 基因缺失，尽管在肠外致病性大肠杆菌（ExPEC）中发现了毒力和耐药基因。
本研究结果表明，巴西牛肉中存在耐热型大肠杆菌，并证实了一些来自巴西牛肉的大肠杆菌中存在 tLST 基因。
