Screening of immunostimulatory probiotic lactic acid bacteria from chicken feces as animal probiotics

The principal objective of this study was to screen and select acid-tolerant Lactobacillus strains from chicken feces, feeds, and other sources. Fourty six strains evidencing acid tolerance (pH 3.5) were isolated in this study. Among them, nine strains exhibited marked immunostimulatory effects. Therefore, nine candidate strains were characterized for probiotic use. In order to evaluate macrophage activation, NO production was measured using RAW 264.7 cells. In particular, three strains (FC812, FC222, and FC113) evidenced the highest levels of NO production measured at 38.39±20.01, 35.06±27.73, and 33.88±15.99 μM, respectively, at a concentration of 10⁸ CFU/mL. The majority of strains, with the exception of strain FC322, evidenced marked resistance to artificial gastric juice (pH 2.5 with 1%(w/v) pepsin). Additionally, strains FC222, FC421, FC511, and FC721 were highly resistant to artificial bile acid (0.1%(w/v) oxgall), whereas strains FC113, FC322, FC422, FC621, and FC812 were the least resistant to bile. All nine strains exerted antimicrobial effects against chicken-related pathogens. Additionally, all nine strains were found to be resistant to several antibiotics. The isolated strains, except for strain FC322, were tentatively identified as Lactobacillus salivarius, using an API 50 CHL kit. These results demonstrate that some probiotic organisms may potentially probiotic properties, and thus may serve as an effective alternative to antibiotics in animal applications.