Characteristics of three listeriaphages isolated from New Zealand seafood environments

To isolate and characterize listeriaphages from seafood environments. METHODS AND

Listeriaphages (phages) isolated from seafood environments were distinguished by physical and biological techniques including restriction digestion of phage DNA. Three phages belonged to order Caudovirales and showed psychrotrophic characteristics. The phages had broad host ranges against 23 Listeria strains by productive infection or at least by adsorption. At 15 ± 1°C, adsorption rate constants of the three phages ranged from 8·93 × 10(-9) to 3·24 × 10(-11 ) ml min(-1) across different Listeria monocytogenes strains. In indicator hosts, the mean burst sizes of phages LiMN4L, LiMN4p and LiMN17 were c. 17, 17 and 11 plaque-forming units (PFU) per cell, respectively, at 15 ± 1°C. The respective latent periods were c. 270 min for phages LiMN4p and LiMN17, whereas for phage LiMN4L, it was c. 240 min.

The three virulent psychrotrophic phages isolated from seafood-processing environments had broad host ranges and low productive replication. These characteristics suggest that the phages may be suitable as passive biocontrol agents against seafood-borne L. monocytogenes.

This is the first report on the isolation of autochthonous virulent listeriaphages from seafood-processing environments and information on single-step replication and adsorption characteristics of such listeriaphages.