Genotypical characterization of thermotolerant coliforms isolated from food produced by a Solidarity Economic Venture of Bahia (Brazil)

Abstract Many Solidarity Economic Venture (SEV) are family farmers who seek to add value to production through artisanal processing, which can lead to food contamination. Thus, this study aimed to genotypically characterize thermotolerant coliforms (TtC) strains from food produced by local agribusinesses of SEV during January to April 2019. Samples from thirteen production units (PU) from the SEV were submitted to a microbiological analysis of thermotolerant coliforms (AFNOR 3M1/2 – 09/89), using a fast count method in Petrifilm™ dishes. The Polymerase Chain Reaction (PCR) technique was used to verify the following virulence genes (VGs) associated with Escherichia coli: stx, typical from enterohemorrhagic E. coli (EHEC); bfpA typical from entheropathogenic E. coli (EPEC) and elt and slt, typical from entherotoxigenic E. coli (ETEC). The results showed that two samples of queijadinha (typical Brazilian candy made with eggs and coconut) and one sample of cassava cake presented characteristic colonies TtC. This way, three strains were isolated in order to perform the PCR technique. However, the genes used in the reaction were not detected in the isolated strains. Therefore, it is suggested that the isolated strains are from E. coli pathotypes with different virulence genes than the ones analyzed belong other types of TtC, such as Enterobacter and Klebsiella. Although the virulence of genes has not been confirmed, the presence of TtC on food indicates hygiene flaws during production and, therefore, measurements to control and prevent contamination should be taken.摘要 多数参与互助经济企业（Solidarity Economic Venture，SEV）的主体为家庭农户，他们尝试通过手工加工提升农产品附加值，但该生产环节可能引发食品污染。为此，本研究旨在对2019年1月至4月期间，来自该互助经济企业当地涉农企业生产的食品中的耐热大肠菌群（thermotolerant coliforms，TtC）菌株进行基因型鉴定。 本研究采集了该互助经济企业旗下13个生产单元（production units，PU）的样品，采用Petrifilm™快速计数平板法，依据AFNOR 3M1/2 – 09/89标准开展耐热大肠菌群微生物学检测。随后采用聚合酶链式反应（Polymerase Chain Reaction，PCR）技术，对与大肠埃希菌（Escherichia coli）相关的以下毒力基因（virulence genes，VGs）进行检测：肠出血性大肠埃希菌（enterohemorrhagic E. coli，EHEC）特异性stx基因、肠致病性大肠埃希菌（enteropathogenic E. coli，EPEC）特异性bfpA基因，以及肠产毒性大肠埃希菌（enterotoxigenic E. coli，ETEC）特异性elt与slt基因。 检测结果显示，2份巴西传统椰丝蛋糖（queijadinha，以鸡蛋与椰子为原料的典型巴西糖果）样品与1份木薯糕样品中检出耐热大肠菌群特征菌落。据此，本研究分离得到3株菌株用于后续聚合酶链式反应检测，但未在分离菌株中检出上述目标毒力基因。因此，本研究推测本次分离得到的菌株，要么属于未携带本次检测范围内毒力基因的大肠埃希菌致病型，要么属于其他类型的耐热大肠菌群，如肠杆菌属（Enterobacter）与克雷伯菌属（Klebsiella）。 尽管未检出目标毒力基因，无法证实菌株的致病性，但食品中检出耐热大肠菌群，表明生产过程存在卫生缺陷，因此需采取相应措施以控制并预防食品污染。