Tran Thao D, Lee Sang In, Hnasko Robert, McGarvey Jeffery A
USDA, ARS, Foodborne Toxin Detection and Prevention Research Unit, Albany, California, USA.
USDA, ARS, Produce Safety and Microbiology Research Unit, Albany, California, USA.
Microb Biotechnol. 2024 Mar;17(3):e14437. doi: 10.1111/1751-7915.14437.
Escherichia coli O157:H7 causes >73,000 foodborne illnesses in the United States annually, many of which have been associated with fresh ready-to-eat produce including cantaloupe melons. In this study, we created a produce-associated bacterial (PAB) library containing >7500 isolates and screened them for the ability to inhibit the growth of E. coli O157:H7 using an in vitro fluorescence-based growth assay. One isolate, identified by 16S and whole-genome sequence analysis as Enterobacter asburiae, was able to inhibit the growth of E. coli by ~30-fold in vitro and produced zones of inhibition between 13 and 21 mm against 12 E. coli outbreak strains in an agar spot assay. We demonstrated that E. asburiae AEB30 was able to grow, persist and inhibit the growth of E. coli on cantaloupe melons under simulated pre- and post-harvest conditions. Analysis of the E. asburiae AEB30 genome revealed an operon encoding a contact-dependent growth inhibition (CDI) system that when mutated resulted in the loss of E. coli growth inhibition. These data suggest that E. asburiae AEB30 is a potential biocontrol agent to prevent E. coli contamination of cantaloupe melons in both pre- and post-harvest environments and that its mode of action is via a CDI system.
在美国，大肠杆菌O157:H7每年导致超过73000例食源性疾病，其中许多与包括哈密瓜在内的新鲜即食农产品有关。在本研究中，我们创建了一个包含7500多个分离株的与农产品相关的细菌（PAB）文库，并使用基于荧光的体外生长测定法筛选它们抑制大肠杆菌O157:H7生长的能力。通过16S和全基因组序列分析鉴定的一株分离菌为阿氏肠杆菌，它在体外能够将大肠杆菌的生长抑制约30倍，并且在琼脂斑点试验中对12株大肠杆菌暴发菌株产生了13至21毫米的抑菌圈。我们证明，在模拟的收获前和收获后条件下，阿氏肠杆菌AEB30能够在哈密瓜上生长、存活并抑制大肠杆菌的生长。对阿氏肠杆菌AEB30基因组的分析揭示了一个编码接触依赖性生长抑制（CDI）系统的操纵子，该操纵子发生突变时会导致对大肠杆菌生长抑制作用的丧失。这些数据表明，阿氏肠杆菌AEB30是一种潜在的生物防治剂，可在收获前和收获后环境中预防大肠杆菌对哈密瓜的污染，其作用方式是通过CDI系统。
