In Vitro Selection of Potential Lactic Acid Bacteria Isolated from Ducks and Geese in Thailand

Abstract

Potential lactic acid bacteria from the feces of ducks and geese in Thailand were selected and their probiotic properties were characterized for animal probiotic supplementation. A total of 104 isolates were subjected to an inhibitory activity test against pathogenic bacteria. The 101 isolates showed varying inhibition zones depending on the target pathogens. Tests for acid and bile tolerance were performed to test the bacterial survival. The results showed that 28 isolates survived in de Man Rogosa Sharp (MRS) medium mixed with 3% fresh chicken bile and in MRS medium at pH levels of 2, 3 and 4. A test of their adhesion ability to host epithelial cells using cell surface hydrophobicity produced a range of 2.72%–27.70%. The isolates were tested to determine their antimicrobial susceptibility profiles with gentamycin, ciprofloxacin, ampicillin, erythromycin, vancomycin and tetracycline. According to the criteria for in vitro probiotics selection, 3 of the 28 lactic acid bacteria isolates showed suitable probiotic properties. The bacteria were identified using phenotypic and genotypic methods. Based on 16S rRNA gene sequences analysis, strains D5-2 and D6-4 were classified as Lactobacillus delbrueckii subsp. bulgaricus ATCC11842T with 99.00% identities, while strain D2-2-1 with 96.62% identities was closely related to L. reuteri F275T.