Complete genomic sequence of the Vibrio alginolyticus bacteriophage Vp670 and characterization of the lysis-related genes, cwlQ and holA

Abstract

BackgroundBiocontrol of bacterial pathogens by bacteriophages (phages) represents a promising strategy. Vibrio alginolyticus, a gram-negative bacterium, is a notorious pathogen responsible for the loss of economically important farmed marine animals. To date, few V. alginolyticus phages have been successfully isolated, and only three complete genome sequences of them have been released. The limited available phage resources and poor genomic data hamper research on V. alginolyticus phages and their applications for the biocontrol of V. alginolyticus.ResultsWe isolated a phage, Vp670, against the V. alginolyticus strain E06333 and obtained its full genomic sequence. It contains 43,121 nucleotides with a GC content of 43.4%, and codes for 49 predicted open reading frames. Observation by electron microscope combined with phylogenetic analysis of DNA polymerase indicates that Vp670 belongs to the subfamily Autographivirinae in the family Podoviridae. orf3 (designated holA) and orf8 (designated cwlQ) are predicted to encode a holin (HolA) and an endolysin (CwlQ), respectively. Expression of holA alone or coexpression of holA and cwlQ from within arrested the growth of Escherichia coli and V. alginolyticus while the expression of cwlQ alone had no effect on the growth of them. Further observation by transmission electron microscopy revealed that the expression of holA vanished the outer membrane and caused the release of cellular contents of V. alginolyticus and the coexpression of holA and cwlQ directly burst the cells and caused a more drastic release of cellular contents. Expression of cwlQ alone in V. alginolyticus did not cause cytomorphological changes.ConclusionsPhage Vp670 is a V. alginolyticus phage belonging to the family of Podoviridae. The genome of Vp670 contains a two-component lysis module, which is comprised of holA and cwlQ. holA is predicted to encode for the holin protein, HolA, and cwlQ is predicted to encode for the endolysin protein, CwlQ. Both holA and cwlQ likely play important roles during the release of phage progeny.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5131-x) contains supplementary material, which is available to authorized users.

Phage Endolysins as Potential Antimicrobials against Multidrug Resistant Vibrio alginolyticus and Vibrio parahaemolyticus: Current Status of Research and Challenges Ahead

“…Cells without expressed genes had intact cellular structures with no morphological difference. Coexpression of both genes has resulted in severe cell damage compared to the expression of holA alone in the cells [57].…”

Application of Bacteriophages to Control Vibrio alginolyticus Contamination in Oyster (Saccostrea glomerata) Larvae

“…Based on the genome analysis and the subsequent growth experiments, it was concluded that the bacteriophages described in this paper were unlikely to be involved in the specialized transduction of host bacterial DNA. The GC content of Φ-1 was very close to that for bacteriophage V. alginolyticus Vp 670 (GC content of 43.4%) [ 39 ] with no ncRNA gene in the genome [ 38 ]. Bacteriophages with tails and a dsDNA genome larger than 200 kb are classified as Jumbo bacteriophage [ 40 ].…”

Comparative genome analyses of five Vibrio penaeicida strains provide insights into their virulence-related factors

“…In other studies, prophages belonging to the family Podoviridae were detected in V. parahaemolyticus [83] and Vibrio alginolyticus [84]. The majority of CDSs of the predicted prophages encoded unknown hypothetical proteins and it is unclear whether the prophages contribute to the virulence of this bacterium.…”