Administering a Bioprotective Strain to Live Fish in Aquaculture Prevents the Growth of Listeria and Spoilage Bacteria on the Processed Fillets

Abstract

Seafood is prone to rapid spoilage and transmission of foodborne diseases. Here, we investigate the effect of the bioprotective strain Carnobacterium divergens V41 on the health of on-growing Atlantic salmon (Salmo salar) and spoilage of its fillets throughout storage. The strain was administered throughout a three-month growth period and applied to the water in the fish tanks prior to harvest to assess its impact on animal health, shelf-life properties of the processed fillets, and growth inhibition of Listeria. Administering the strain through feed for three months had no adverse effect on the farmed fish, and no significant differences were detected in growth or mortality between the treatment and control groups. However, adding C. divergens V41 to the tank water prior to harvesting markedly changed the fillet microbiome, suppressing the growth of spoilage organisms and thereby possibly extending the shelf-life period. A Listeria challenge test demonstrated that exposure of the fish to C. divergens V41 prior to harvesting and processing resulted in over 99.9 % inhibition of Listeria growth on the fillets over a 21-day period, compared with the control group. This is the first study to show that administering a bioprotective strain to live farmed fish can have a bioprotective effect on fish fillets after processing. This is a simple method to modify the food microbiome of a rapidly perishable product without specialized equipment, thereby increasing food safety and reducing food waste.