Genome characterization of the novel lytic Vibrio parahaemolyticus phage

A lytic bacteriophage, designated Vibrio phage vB_VpP_BA6, was isolated from sewage collected in Guangzhou, China. The double-stranded DNA genome of phage BA6 is composed of 50,520 bp with a G+C content of 41.77%. It possesses 64 open reading frames relating to phage structure, packaging, host lysis, DNA metabolism, and additional functions. Three tRNAs genes (encoding Pro, Ile and Trp) were detected. Comparison of its genomic features and phylogenetic analysis revealed that phage BA6 is a novel member of the family Podoviridae. This phage may represent a potential therapeutic agent against multidrug-resistant Vibrio parahaemolyticus. Vibrio parahaemolyticus is a halophilic Gram-negative foodborne bacterium that is commonly found in fish, shrimp, and other aquatic animals. As a pathogen of humans and other animals, it not only causes important economic losses to the aquaculture industry [1] but also threatens food safety, inducing severe diarrhea and acute gastroenteritis in humans worldwide [2]. To control V. parahaemolyticus, the use of antibiotics has become a standard practice worldwide, and, as an undesirable result of decades of application, an increasing number of multidrug-resistant pathogenic bacteria are appearing. Microbiological risk assessments indicate that both aquatic products and ready-to-eat foods in China can be contaminated by antibiotic-resistant V. parahaemolyticus, with the highest resistance rates observed against streptomycin [3–5]. Bacteriophages (phages) are abundant biological entities composed of either DNA or RNA enclosed in a protein coat. Usually, multiple phage particles are released by lysis of the bacterium in a short cycle [6]. Since lysis disrupts hosts cells, phage therapy is considered an environmentally friendly alternative for reducing and controlling drug-resistant pathogenic bacteria. In this study, vB_VpP_BA6 was isolated from a sewage sample collected in the Huangsha aquatic product market in Guangzhou, China. Multidrug-resistant V. parahaemolyticus 23201444 (Amp+, Cfz+, Cpt+, Str+, Kan+, Gen+) was provided for this study by the Guangdong Institute of Microbiology. Phages in the fluid sample were concentrated by membrane filter adsorption and elution as described previously [7]. Each lytic phage was isolated and purified at least 10 times and then incubated for 4 h at 37°C in a double-layer agar plate. The host range of each phage was determined by spot assay [8], and morphological characteristics were observed under a transmission electron microscope (TEM, Hitachi H-7650). Phage DNA was extracted using phenol, chloroform, and isoamyl alcohol [9]. The complete genome of vB_ VpP_BA6 was sequenced on the Ion Torrent S5 platform (Thermo Fisher Scientific, USA) [10]. Before complete Handling Editor: Johannes Wittmann. Meiyan Yang, Yongjian Liang are contributed equally to this work. Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s0070 5-019-04351 -5) contains supplementary material, which is available to authorized users. * Qingping Wu wuqp203@163.com 1 State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Xianlie Zhong Road 100, Guangzhou 510070, Guangdong, China 2 College of Agriculture, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China 3 Department of Food Science and Technology, Jinan University, Guangzhou 510632, China