Identification of food borne pathogens in fermented fish by polimerase chain reaction and their elimination by probiotic bacteria

The influence of lactic acid bacteria and brine solutions on food-borne pathogens and biogenic amine formation in fermented rainbow trout (Oncorhynchus mykiss) fillets were investigated. Rainbow trout fillets were initially inoculated with different lactic acid bacteria (LAB) and food-borne pathogenic bacteria (PB) during the fermentation process (7 days) and then vacuum packed for 42 days at 4 ±1 °C. Fresh fish fillets were divided into four groups: group 1 (G1) inoculated with LAB and PBS without salt solutions, group 2 (G2) and group 3 (G3) with different salt concentration inoculated with LAB and PBS, and group 4 (G4) without any LAB inoculation The results of the polymerase chain reaction (PCR) analysis confirmed that fermented fish had most of the contaminant pathogens. Initial mesophilic total viable count (TVC) of fresh trout was 4.7 log cfu /g, while TVC values of trout fillets after 7 days of fermentation process were 5.9 log cfu/g for G1, 5.4 log cfu/g for G2, 5.4 log cfu/g for G3 and 5.6 log cfu/g for G4. LAB strains showed higher antimicrobial activity against Salmonella than that of Listeria. The inhibition effect of used salt concentrations on growth of E. coli was low until 28 days of storage. Initial histidine content of fermented trout was 2.61 mg/100 g and reached 4.11 mg/100g for G4. The study result showed ammonia and BA production was influenced by salt concentration, glucose, potassium nitrate and the presence of LAB and PBS.