Isolation, characterization and genome analysis of ΦImVa-1, a novel bacteriophage infecting Vibrio alginolyticus strain ATTC 17749

Vibrio alginolyticus is a Gram-negative bacterium commonly associated with mackerel poisoning. A bacteriophage that specifically targets and lyses this bacterium could be employed as a biocontrol agent for treating the bacterial infection or improving the shelf-life of mackerel products. However, only a few well-characterized V. alginolyticus phages have been reported in literature. Thus, this study was carried out with the main aims to isolate and characterize a novel bacteriophage against V. alginolyticus. As a result, a novel lytic phage, namely ΦImVa-1, specifically infecting V. alginolyticus strain ATCC 17749, was isolated from Indian mackerel. The bacteriophage was analyzed with electron microscopy, and protein profile of the phage was studied with sodium dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The phage growth was characterized by the one-step kinetics growth curve, adsorption rate and the effects of pHs and temperatures on the phage-host interactions. The phage genome was characterized and analyzed by whole genome sequencing and bioinformatic analysis. The phage has a short latent period of 15 minutes and a burst size of approximately 66 particles per infected bacterium. ΦImVa-1 remained stable for 2 hours at a wide temperature (27-75 ℃) and a broad pH (3-11) range. Transmission electron microscopy revealed that ΦImVa-1 has an icosahedral head with a short tail, resembling those in the Schitoviridae family. High throughput sequencing and bioinformatics analysis elucidated that ΦImVa-1 has a linear dsDNA genome of 77,479 base pairs (bp), with a G+C content of ~38.72% and 110 predicted gene coding regions (106 open reading frames and four tRNAs). The genome contains an extremely large virion-associated RNA polymerase gene and two smaller non-virion-associated RNA polymerase genes, which are hallmarks of schitoviruses. No antibiotic genes were found in the ΦImVa-1 genome. When raw mackerel fish slices were treated with ΦImVa-1, the pathogen loads reduced significantly, demonstrating the potential of the phage as a biocontrol agent for V. alginolyticus strain ATCC 17749 in the food. In conclusion, this study has provided insights into the biological and genomic properties of the phage ΦImVa-1, a novel schitovirus that specifically infects V. alginolyticus ATCC 17749.

Text 125084 - Full Text.pdf Download (4MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18803

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