The protective effect of Bdellovibrio-and-like organisms (BALO) on tilapia fish fillets against Salmonella enterica ssp. enterica serovar Typhimurium

AIMS: To characterize freshwater Bdellovibrio-and-like organisms (BALO) isolated in China and examine their potential in controlling growth of Salmonella enterica ssp. enterica serovar Typhimurium on tilapia fillets. METHODS AND RESULTS: Four BALO isolates were recovered from a pond in Yanzhou of Shandong province, China, with Salm. Typhimurium as prey using double-layer agar method. Partial 16S rDNA sequencing analysis identified BD2GL, BD5GL and BDXGL as Bdellovibrio bacteriovorus and BD2GS as a Peredibacter sp. Lysis experiments on 32 potentially pathogenic strains revealed that BALO lysis rates are in the range of 56.3-65.6%. On the five Salmonella strains tested, only BD2GS achieved 100% lysis rate. When applied on tilapia fillets against Salm. Typhimurium, BD2GS showed its growth control potential. Cell increments of Salm. Typhimurium were significantly lower (P < 0.05) in two BD2GS-treated groups compared to control and low-dose group (BD2GS to prey ratio, 1 : 1) was more effective than high-dose group (BD2GS to prey ratio, 10 : 1) in controlling Salm. Typhimurium growth. CONCLUSIONS: Results of this study indicated that BD2GS could control Salm. Typhimurium growth on tilapia fillets. SIGNIFICANCE AND IMPACT OF THE STUDY: BALO could be used as a live protective culture in controlling bacterial growth and ensure food safety.