Isolation, characterization and application of a novel bacteriophage BtpYZU01 against Brochothrix thermophacta in aquatic products

Abstract

Brochothrix thermosphacta is a predominant and spoilage bacterium in different chilled vacuum-packaged aquatic products. Bacteriophages have been extensively studied for the biocontrol of spoilage bacteria in order to maintain the quality and shelf-life of foods. In this study, a highly lytic bacteriophage BtpYZU01 against B. thermosphacta was isolated from a domestic sewage sample in Yangzhou, and its morphological, biological, and genomic features were characterized. Morphology, one-step growth, thermal and pH stability results indicated that the phage BtpYZU01 was a member of Siphoviridae, with large burst sizes and relatively short latent periods, and strong resistance to extreme pH. Sequence analysis showed that BtpYZU01 had 52 open reading frames (ORFs), but without genes related to antibiotic resistance, toxin, lysogeny and virulence factors. B. thermosphacta in LB was significantly inhibited by the presence of phage BtpYZU01 at 25 °C. In the fish juice model, the counts of B. thermosphacta were also decreased after phage treatment at both at 25 °C and 4 °C. Based on the above features, BtpYZU01 could be served as a novel phage candidate to biological control of B. thermosphacta in meat and aquatic products.