Amarillas Luis, Chaidez Cristóbal, González-Robles Arturo, Lugo-Melchor Yadira, León-Félix Josefina
Laboratorio de Biología Molecular y Genómica Funcional, Centro de Investigación en Alimentación y Desarrollo, A. C., Culiacán, Sinaloa, México; Laboratorio de Genética, Instituto de Investigación Lightbourn, A. C., Cd. Jiménez, Chihuahua, México.
Inocuidad Alimentaria, Centro de Investigación en Alimentación y Desarrollo, A. C. , Culiacán, Sinaloa , México.
PeerJ. 2016 Sep 13;4:e2423. doi: 10.7717/peerj.2423. eCollection 2016.
Shiga toxin-producing Escherichia coli (STEC) is one of the most common and widely distributed foodborne pathogens that has been frequently implicated in gastrointestinal and urinary tract infections. Moreover, high rates of multiple antibiotic-resistant E. coli strains have been reported worldwide. Due to the emergence of antibiotic-resistant strains, bacteriophages are considered an attractive alternative to biocontrol pathogenic bacteria. Characterization is a preliminary step towards designing a phage for biocontrol.
In this study, we describe the characterization of a bacteriophage designated phiC119, which can infect and lyse several multidrug-resistant STEC strains and some Salmonella strains. The phage genome was screened to detect the stx-genes using PCR, morphological analysis, host range was determined, and genome sequencing were carried out, as well as an analysis of the cohesive ends and identification of the type of genetic material through enzymatic digestion of the genome.
Analysis of the bacteriophage particles by transmission electron microscopy showed that it had an icosahedral head and a long tail, characteristic of the family Siphoviridae. The phage exhibits broad host range against multidrug-resistant and highly virulent E. coli isolates. One-step growth experiments revealed that the phiC119 phage presented a large burst size (210 PFU/cell) and a latent period of 20 min. Based on genomic analysis, the phage contains a linear double-stranded DNA genome with a size of 47,319 bp. The phage encodes 75 putative proteins, but lysogeny and virulence genes were not found in the phiC119 genome.
These results suggest that phage phiC119 may be a good biological control agent. However, further studies are required to ensure its control of STEC and to confirm the safety of phage use.
产志贺毒素大肠杆菌（STEC）是最常见且分布广泛的食源性病原体之一，常引发胃肠道和尿路感染。此外，全球多地报道了多重耐药大肠杆菌菌株的高发生率。由于耐药菌株的出现，噬菌体被认为是控制病原菌的一种有吸引力的替代方法。特性鉴定是设计用于生物防治的噬菌体的初步步骤。
在本研究中，我们描述了一种名为phiC119的噬菌体的特性，它可以感染并裂解几种多重耐药STEC菌株和一些沙门氏菌菌株。使用PCR筛选噬菌体基因组以检测stx基因，进行形态分析，确定宿主范围，并进行基因组测序，以及分析粘性末端并通过基因组酶切鉴定遗传物质类型。
通过透射电子显微镜对噬菌体颗粒的分析表明，它具有二十面体头部和长尾巴，这是长尾噬菌体科的特征。该噬菌体对多重耐药和高毒力大肠杆菌分离株表现出广泛的宿主范围。一步生长实验表明，phiC119噬菌体呈现出较大的爆发量（210 PFU/细胞）和20分钟的潜伏期。基于基因组分析，该噬菌体包含一个大小为47,319 bp的线性双链DNA基因组。该噬菌体编码75种推定蛋白，但在phiC119基因组中未发现溶原性和毒力基因。
这些结果表明噬菌体phiC119可能是一种良好的生物防治剂。然而，需要进一步研究以确保其对STEC的控制并确认噬菌体使用的安全性。
