IN VITRO SCREENING OF LACTIC ACID BACTERIA ISOLATED FROM WILD BIRDS FOR FUTURE PROBIOTIC DEVELOPMENT
Jeong S., Kwon J., Gwon G., Kim K., Song C.
Konkuk University, South Korea
Intestinal microbiota plays a crucial role in maintaining health by helping nutrient utilization, inhibiting enteric pathogen colonization, and generating greater immune capacity. Since 2011, antibiotic supplement in animal feed has been completely banned in South Korea, and as a consequences, the need for probiotic agent with exceeding ability of promoting immune activity has been rapidly growing. Lactic acid bacteria isolated from fermented food is widely used for animal consumption in South Korea, but animal-originated LAB also has possibility of better host colonization and immune activation. The aim of present work is to evaluate the probiotic potential of lactic acid bacteria (LAB) strains isolated from wild duck and to select probiotic candidates for animal, especially for poultry use.
Thirtyfour (34) lactic acid bacteria strains (11 Lactobacillus, 3 Enterococcus, 2 Weissella, 1 Pediococcus, 1 Streptococcus) were isolated from the intestinal tract (crop, proventriculus, small intestine and cecum) of wild duck (2 mallards, 2 common teal, 1 pin-tailed duck, 2 widgeons). 5 in vitro tests for screening probiotic potential were conducted - survival test in 2 artificial gastrointestinal conditions (pH 2.5 gastric acid with 4mg/ml pepsin, and 0.3% bile acid), antibiotic susceptibility test to 9 antibiotics (ampicillin, vancomycin, gentamicin, kanamycin, streptomycin, erythromycin, tetracycline, chloramphenicol, clindamycin), antimicrobial activity test against Salmonella Enteritidis, and Caco-2 cell (human colon adenocarcinoma cell line) surface adhesion assay.
1 Lactobacillus strains survived at highest final population (>10^7 cfu/ml) and 2 survived at moderate high final population (>10^5 cfu/ml) after 3 hours of exposure at low pH. Most of the tested strains displayed partial to complete resistance to bile salt even after 24 hours of exposure. Tested strains exhibited variable abilities of adhesion to Caco-2 cells and variable susceptibility to 9 antibiotics. Some of the strains had considerable anti-Salmonella activity.
Totally, most of the wild bird intestinal tracts-originated lactic acid bacteria strains tested in this study exhibited poor resistance to low pH compared to early studied lactic acid bacteria strains isolated from fermented food with low pH condition like Kimchi or Toenjang (soy bean paste), traditional foods of Korea. But survival at low pH, bile acid tolerance, and intestinal cell adhesion ability of some strains are indicating that these strains can colonize in harsh condition of animal gastrointestinal tract successfully. Also, antimicrobial activity against Salmonella, which is one of the most causal agent of economic loss and public health problems in poultry markets, is indicating the great possibility of future probiotic use which can partially substitute antibiotics. Selected strains are in need of further investigations including in vivo studies about their probiotic functions in target animal to confirm health benefits and describe the mechanisms of action.
Keywords: Lactic acid bacteria, Probiotics, In vitro screening, Intestinal microbiota, Wild bird
Jeong S., et al. (2016). In vitro screening of lactic acid bacteria isolated from wild birds for future probiotic development. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 100.). IPC2016