Screening and characterization of potential probiotic lactic acid bacteria from cultured common carp intestine.

Screening of potential probiotic LAB for aquaculture from adult common carp intestine was performed seasonally. Lactococcus lactis h2 and Lactococcus raffinolactis h47, which show cholic acid resistance and strong antibacterial activity against fish pathogens, were selected from predominant LAB in summer and winter respectively. Enterococcus pseudoavium h50, with the strongest antimicrobial activity among the strains isolated through 1 year, was also selected. Streptococcus iniae I1, with strong antimicrobial activity, was selected from predominant LAB in young common carp intestine. Direct screening of LAB with cholic acid resistance was also carried out seasonally. The antibacterial activity of the isolates was tested, and Lactobacillus fuchuensis K11 was selected from the summer isolates. In addition, five candidate strains were selected from the winter samples. The candidates' levels of cholic acid resistance and antibacterial activity were better than or at the least matched those of their corresponding type strains. All the candidates grew over a wide range of temperatures.