Genome Analysis of Two Novel Lytic Vibrio maritimus Phages Isolated from the Coastal Surface Seawater of Qingdao, China.

Two novel Vibrio phages, LP.1 and LP.2 that infected Vibrio maritimus R-40493, were isolated from surface seawater in Qingdao coastal area by the double-agar layer method. Morphological analysis by transmission electron microscope showed that the two phages displayed head-tail structures with icosahedral heads of 62.37 and 54.00 nm in diameter and long non-contractile tails of 119.00 and 105.20 nm in length, respectively, and can be grouped into the Siphoviridae family. Thermal and pH sensitivity tests exhibited that LP.1 was stable at temperature ranging from - 20 to 65 °C and at pH ranging from 5 to 12, and LP.2 showed vitality over a wider range of temperature (- 20-75 °C) and pH (3-12). Both LP.1 and LP.2 contained linear and double-stranded DNA genomes with a length of 46,791-bp and 37,128-bp, respectively. The genome of both phages can be classified into four functional groups, including DNA replication and regulation, phage packaging, phage structure, and additional function. The bioinformatic analysis demonstrated that the Vibrio phages LP.1 and LP.2 are novel phages. By conducting morphological, biochemical, and genomic analysis, our study provides useful information for further research on the interaction between Vibrio phages and their host.