IDENTIFICATION OF MICROFLORA OF FRESHWATER FISH CAUGHT IN THE DRIKSNA RIVER AND POND IN LATVIA

Identification of freshwater fish microflora is an important tool for evaluation of quality and safety of fish intended for human consumption. The aim of the present study was to detect the microflora of freshwater fish caught by fishermen. Altogether, 23 samples of freshwater fish were collected from fishermen from two different water sources - Driksna river and pond in Dobele. For detection of microbiological contamination, fish samples were tested for the total bacterial count (TBC), coliforms, Enterobacteriaceae and zoonotic pathogenic microorganisms - Salmonella spp., Listeria spp., and Yersinia spp. Identification of bacterial species was carried out by the MALDI-TOF MS Biotyper. TBC ranged from 2.7 to 4.78 log(10) CFU g(-1) and 3.68 to 4.11 log(10) CFU g(-1), coliforms from 2.55 to 4.10 log(10) CFU g(-1) and 1.38 to 2.73 log(10) CFU g(-1), Enterobacteriaceae from 1.95 to 4.05 log(10) CFU g(-1) and 1.72 to 2.69 log(10) CFU g(-1) in pond and river fish samples, respectively. Between two fishing locations, fish caught in pond carried the significantly higher number of TBC, coliforms and Enterobacteriaceae than fish from the river (P>0.05). Freshwater fish microflora consisted of Pseudomonas spp. (55%), Serratia spp. (7%), Candida spp. (6%), Rahnella spp. (7%), Pantoea spp. (9%), Aeromonas spp. (5%), Buttiauxella spp. (8%), Stenotrophonomas spp. (2%) and Enterobacter spp. (1%). Salmonella spp., Listeria spp. and Yersinia spp. were not identified. Despite the human pathogenic microorganisms were not identified in the present study, the composition of microflora and especially the abundance of Pseudomonas spp. indicates that the fish are prone to spoilage process development that potentially may alter the quality of freshwater fish meat.