Characterization and Genomic Analysis of a Broad-Spectrum Lytic Phage PG288

Abstract

Vibrio parahaemolyticus is an important zoonotic pathogen that can cause severe diseases and even death in aquatic animals and humans. With the widespread use of antibiotics gradually losing their effectiveness, phages that can specifically lyse bacteria are receiving increasing attention as a useful alternative antibacterial strategy. This study characterized a lytic phage, PG288, which was isolated by using V. parahaemolyticus strain G855 as host strain. Morphologically, phage PG288 has a polyhedral head and a long, non-retractable tail. Bactericidal assays revealed that phage PG288 exhibited a strong lytic ability on V. parahaemolyticus strain G855 and a broad host range, as evidenced by the ability to infect several distinct Vibrio species. The one-step growth curve showed that the latent period of phage PG288 was about 50 min, and the burst size was about 92 PFU per cell. Furthermore, phage PG288 remained quite stable in a temperature range of 20-50℃ and a pH range of 4-10. Genomic analysis revealed that phage PG288 contained 105 ORFs but no genes associated with antibiotic resistance, virulence, and lysogenic activity. Phylogenetic analysis confirmed that it is a new member of the genus Mardecavirus class Caudoviricetes. All data of this study indicate the phage and is a good potential candidate for phage therapies against Vibrio infection, and also provide beneficial complements of the phage database.

Keywords: Vibrio parahaemolyticus, phage, broad host-range, genomic analysis