84 MI19 Evaluation and selection of Lactic acid bacteria based on inhibition capability against Streptococcus suis for probiotics product N. Innamma1*, P. Thitisak2, N. Banglarp2, A. Songsujaritkul2, S. Hankla2 & K. Kaeoket1 1Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand 2K.M.P.Biotech Co., Ltd., Chonburi, Thailand *E-mail: [email protected] Streptococcus suis (S. suis) serotype 2 is one of the most important pathogens in pigs, which causes septicemia, meningitis, arthritis and pneumonia pigs. Moreover, this bacterium is considered an emerging zoonotic agent. Recently, increased antibiotic resistance of S. suis has been reported worldwide, and raises issues regarding food safety. There are several potential alternative methods to replace the use of antibiotics. One of them is to promote pig health by directly supplement probiotic bacteria and another is to use their antimicrobial substance, to inhibit the growth of pathogens. The objective of this study was to evaluate the potential of cell-free supernatant of selected lactic acid producing probiotic strains to inhibits the growth of 12 isolated S. suis (i.e. SS-01 to SS-12), in which isolated from infected nursery pig and its pathogenicity was confirmed by PCR technique. All the probiotic bacterial strains used in this study (Lactobacillus plantarum, Lactobacillus acidophilus and Pediococcus pentosaceus) were selected mainly on the in vitro of inhibition ability on Enterotoxigenic E. coli, Enterohemorrhagic E. coli and the adhesion ability on swine intestinal mucus as shown in our previous study. The ability of different probiotic species and stains to inhibits S. suis serotype 2 was evaluated by zone of activity on agar well diffusion. The zone of activity was classified into four groups: no inhibition as follows: 0-7 mm; low inhibition: 8-14 mm.; medium inhibition: 15-21 mm., and high inhibition: >21 mm. The different lactic acid probiotics showed variety of capability to inhibit the growth of S. suis serotype 2. Lactobacillus plantarum KMP-F23-1 showed both medium and high inhibition zone of activity for SS-08, SS-03, SS-10 (i.e. 18.25, 26.00, and 21.75 mm., respectively) when compared with other lactic acid producing probiotics. Lactobacillus plantarum CU20 also showed medium and high inhibition zone of activity for SS-06, SS-07, SS-08, and SS-10 strains (i.e. 17.50, 17.50, 17.75, and 21.25 mm., respectively). Lactobacillus acidophilus KMP-TC001 showed high inhibition zone of activity with a diameter of 21.50 for SS-10. For Pedicococcus spp., Pediococcus pentosaceus PdAvPd02 showed high inhibition zone of activity for SS-10 (i.e. 20.00 mm.). According to inhibition zone of activity, we, therefore, included only Lactobacillus and Pedicococcus that showed medium to high inhibition zone of activity to become probiotics candidate in probiotic product, targeting this multi-strains probiotic product is able to minimize the growth of S. suis in pigs. In conclusion, different lactic acid producing probiotics such as Lactobacillus spp. and Pediococcus spp. showed variety of inhibition zone of activity for S. suis, thus we recommended that multi-strains of probiotics should be included in particular product in order to conquer the S. suis problem in pig industry. Keywords: Probiotics, lactic acid bacteria, Streptococcus suis, inhibition, pig 3rd International Symposium on Alternatives to Antibiotics (ATA) Challenges and Solutions in Animal Health and Production .