Department of Biotechnology, Faculty of Chemical Engineering, Ho Chi Minh City University of Technology, VNU-HCM, Ho Chi Minh City, Vietnam.
J Appl Microbiol. 2018 Jun;124(6):1610-1616. doi: 10.1111/jam.13696. Epub 2018 Mar 25.
To construct a simple method to detect Escherichia coli in ready-to-eat fresh vegetables using broad-host-range recombinant phages.
Firstly, a gene encoding cytochrome c peroxidase (CCP) chromogenic enzyme was inserted into genomes of wild-type phages IP008 and IP052 to produce recombinant phages IP008BK and IP052BK. They were then used in the production of the chromogenic enzyme (CCP) through infection into E. coli. The method was then examined in the colorimetric detection of E. coli K12 in broth, and its appearance was confirmed by a significant change in absorbance after a few minutes of the enzyme assay. Secondly, the protocol using the recombinant phages for the detection of E. coli in vegetables, that is, lettuce and mustard greens, was investigated. A low E. coli concentration at 4 CFU per g vegetable was detected within 16·5 h that is of a shorter duration than agar plate methods and in some commonly known phage-based methods.
The existence of E. coli as a faecal contamination indicator in two types of ready-to-eat fresh vegetables, that is, lettuce and mustard greens, can be identified by the broad-host-range recombinant phages.
The method is simple and convenient since it enables the detection of E. coli without expensive apparatus. It is applicable to other types of food samples.
利用广宿主范围重组噬菌体构建一种简单的方法来检测即食新鲜蔬菜中的大肠杆菌。
首先，将细胞色素 c 过氧化物酶（CCP）显色酶基因插入野生型噬菌体 IP008 和 IP052 的基因组中，得到重组噬菌体 IP008BK 和 IP052BK。然后，通过感染大肠杆菌来产生显色酶（CCP）。该方法随后在肉汤中对大肠杆菌 K12 的比色检测中进行了检验，并在酶测定几分钟后通过吸光度的显著变化得到了确认。其次，研究了利用重组噬菌体检测蔬菜（生菜和芥菜）中大肠杆菌的方案。在 16.5 小时内，可检测到每克蔬菜中低至 4 CFU 的大肠杆菌，检测时间短于琼脂平板法和一些常见的基于噬菌体的方法。
利用广宿主范围重组噬菌体可以检测到两种即食新鲜蔬菜（生菜和芥菜）中作为粪便污染指示物的大肠杆菌的存在。
该方法简单方便，因为它可以在没有昂贵仪器的情况下检测大肠杆菌。它适用于其他类型的食品样本。
