Toxicity evaluation of a strain isolated from pollack digestive tract using Paramecium caudatum

A strain was isolated from the digestive organs of Walleye pollack residing in the East Sea of the DPR Korea, which not only produces cryophilic protease, organic acid but also has intestinal adhesion property and bacteriostatic activity against pathogens. The strain was classified and identified as Pseudomonas fragi by genetic system classification methods and registered as KCCC 10110 at the Korean Centre for Culture Collection (KCCC) of the State Academy of Sciences, DPR KOREA. In vivo and in vitro toxicity of Pseudomonas fragi KCCC 10110 was evaluated using Paramecium caudatum. In the treatments with P. fragi KCCC 10110, Bacillus subtilis KCCC 11214 and Lactobacillus lactis KCCC 13208, all of these being well known as non-toxic and probiotic for animals and fishes, higher microbial counts and normal movement of P.caudatum were observed while significant lower cell numbers and abnormal movement of P.caudatum were shown in the treatments with pathogenic strains Clostridium tetani 473, Salmonella typhosa 901 and Aeromonas punctata 823. These results suggest that probiotic and pathogenic bacteria have different influence on Paramecium caudatum and that the strain isolated from Walleye pollack digestive tract is non-toxic.