Determination of the microbial flora of the fish processing plant and the effect of the commercial disinfectants on the isolated strains

Samples were taken from the gilt-head sea bream (Sparus aurata) and the sea bass (Dicentrarchus labrax) and the surface of the processing plants in the research. The specimens were obtained from a commercial processing plant in Bodrum (Mugla-Turkey). 100 fish specimens and 150 surface samples were taken from 10 different sections of the processing plant and these samples were taken every week over a period of 6 months (2016, in May-October). There is a statistically significant difference between the number of bacteria in the fish and surface samples (p≤0.05). The bacterial agents isolated from the fish and processing plant surfaces were identified via phenotypic tests and API® diagnostic test kits. As a result of identification of 10 coliform bacterial strains, it was found that it included the species of Aeromonas hydrophila (30%), Raoultella planticola (10%), Raoultella ornithinolytica (10%), Klebsiella oxytoca (30%). As a result of identification of 15 Vibrio spp. agents, it was detected that it included the species of V.alginolyticus (13%), the possibility of Bibersteinia trehalosi (6%), V.fluvialis (20%), Ewingella americana (the possibility of Erwinia spp. (6%), Photobacterium damselae (the possibility of Bibersteinia trehalosi) (6%), Aeromonas hydrophila (the possibility of V.fluvialis) (6%), Enterobacter cloacae (6%). As a result of identification of 25 Pseudomonas spp. bacterial strains, it was determined that it included the species of P. alcaligenes (8%), P.stutzeri (16%), P.fluorescens (36%), P.mendocina (4%), P.putida (8%), Aeromonas salmonicida (16%), Burkholderia cepacia (8%) and Ralstonia pickettii (4%). As a result of identification of 25 Staphylococcus spp. bacterial strains, it was determined that it included the species of S.hominis (24%), S.saprophyticus (8%), S.warneri (16%), S.sciuri (12%), S.xylosus (4%), S.epidermidis (12%) and S.aureus (24%). The effectiveness of four different disinfectants consisting of chlorine, quaternary ammonium compounds, glutaraldehyde and hydrogen peroxide were determined with Quantitative Suspension Test. Disc Diffusion analyses were realized for this purpose. Thus, the effect spectrums of disinfectants and the suitable amount of concentrations to be used were determined. When the test results in which P. fluorescens was used as a test bacteria were examined, it was found that it was resistant to the low concentrations of the disinfectants (0,5%, 1%). It was determined that S. aureus were susceptible to all disinfectant concentrations (0,5%, 1%, 2%). It was determined that P. fluorescens and S. aureus were usually resistant to chlorine-based disinfectants. The microbicidal effect of chlorine was found between the 3,3- 4,3 log in both bacteria groups. Moreover, the disinfectant effect of vinegar on the isolated strains was investigated. The effects of the three different vinegar brands in the market and six types of vinegar made from five different raw materials (white, apple, barrel grapes, rose, pomegranate, grape vinegar) on bacteria were examined. The effect of rose vinegar (0,25%, 0,5%,1% concentrations) used as a test bacteria of P. fluorescens in the tests was found 9,5 log microbicidal. It was determined that the white vinegar (concentrations of 4%, 3%, 2%) had the effect of 5,2 log microbicidal on S. aureus. As a result, the bacterial contamination points and the types of bacteria resulting from contamination in the processing plant and throughout the fish processing stages were determined. In addition, the residual microflora of the processing plant and the effectiveness of different disinfectants were determined. It was revealed that chlorine-based disinfectants did not have microbicidal effect on bacterial strains. The vinegar did not have a broad spectrum