Screening lactic acid bacteria from swine origins for multistrain probiotics based on in vitro functional properties

Abstract

Lactic acid bacteria originated from swine feces and intestines were selected for potential probiotics based on their bile-salt resistance, low pH tolerance, potential adhesion to epithelial cells and especially functional properties, including production of antimicrobial substances, bile-salt hydrolase (BSH) and amylolytic activity. Results showed 7 isolates with antimicrobial activity, 5 with BSH activity and 3 with amylolytic activity were preliminarily selected from 485 lactic acid bacteria based on their highest potential with functional properties in vitro. The 15 isolates were further assayed on the essential characteristics as potential probiotics. All isolates were fully tolerant to 0.3% bile salts and 11 of them were able to resist pH 3 for 3 h without loss of viable cells. The eleven isolates were then evaluated on their adhesion capability. Wide variation in the hydrophobic character and specific adhesion efficiency was observed and three isolates G1-1, G22-2 and G8-5, with respective antimicrobial, BSH and amylolytic activities were finally selected. In addition, the three isolates were compatible in the coexistence assay. Isolate G1-1 was identified as Lactobacillus salivarius by API system and a 16S rRNA gene sequence analysis. Both G8-5 and G22-2 showed the closest homology to Lactobacillus reuteri according to their 16S rRNA gene sequences (99%). From the study, the three Lactobacilli strains were shown to share the functional properties necessary for probiotics use in animal additives. Their compatibility with respective in vitro activities was expected to show enhanced in vivo efficacy after combination for multistrain probiotics use.