The public impact of V. parahaemolyticus, non-O1/O139 V. cholerae and V. vulnificus in bivalves is relevant and current decontamination processes are not always effective. We believe that the predator HBXCO1 represents a potential candidate for the development of strategies of biocontrol of pathogenic vibrios in bivalves from harvesting to trade.

Summary Bdellovibrio bacteriovorus is a predator micro‐organism towards other Gram‐negative bacteria. We tested B. bacteriovorus to control Escherichia coli growth on chicken slices and canned beef. Moreover, we analysed B. bacteriovorus's lytic ability on eight toxigenic or multidrug‐resistant E. coli strains. In chicken slices, the predator induced the highest prey reduction (4.3 log) respect to control at 6 h. In canned beef, the predator induced the highest prey reduction (2.1 log) respect to control at 6 h. Moreover, B. bacteriovorus showed lytic ability towards all tested E. coli strains. B. bacteriovorus could control E. coli and other pathogenic and spoilage bacteria in those meat‐based foods that have a shelf life <10 days. It could integrate modified atmosphere packaging (MAP) to prolong the shelf life and improve the safety of pre‐packed fresh meat, meat preparations and meat products. In future applications on meat‐based foods, B. bacteriovorus could also minimise the use of additives.

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This research aimed to study the abundance and molecular diversity of Vibrio parahaemolyticus-specific Halobacteriovorax strains isolated from seawater of the Adriatic Sea and the relationship between predator and prey abundances. Moreover, predator efficiency of the Halobacteriovorax isolates toward V. parahaemolyticus and Vibrio cholerae non-O1/O139 strains was tested. V. parahaemolyticus NCTC 10885 was used as primary host for the isolation of Halobacteriovorax from seawater by the plaque assay. Molecular identification was performed by PCR detection of a fragment of the 16S rRNA gene of the Halobacteriovoraceae family members. Moreover, 700 bp PCR products were sequenced and compared between them and to clones described for other sampling sites. Vibrio counts were performed on TCBS agar from 100 ml of filtered water samples and presumptive colonies were confirmed by standard methods. Predatory efficiency of Halobacteriovorax isolates was tested by monitoring abilities of 3-day enrichments to form clear lytic halos on a lawn of Vibrio preys, by the plaque assay. Out of 12 seawater samples monthly collected from June 2017 to May 2018, 10 were positive for V. parahaemolyticus specific Halobacteriovorax with counts ranging from 4 to 1.4 × 10 3 PFU per 7.5 ml. No significant relationship was found between Halobacteriovorax and Vibrio abundances. The 16SrRNA sequences of our Halobacteriovorax strains, one for each positive sample, were divided into three lineages. Within the lineages, some sequences had 100% similarity. Sequence similarity between lineages was always <94.5% suggesting that they may therefore well belong to three different species. All Halobacteriovorax isolates had the ability to prey all tested