Potential probiotic of Lactobacillus strains isolated from the intestinal tracts of pigs and feces of dogs with antibacterial activity against multidrug-resistant pathogenic bacteria.

The occurrence of multidrug-resistant pathogenic bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Acinetobacter baumannii (MDRAB), extended-spectrum β-lactamase (ESBL) Escherichia coli, and Pseudomonas aeruginosa, has become a serious problem in animals and public. The objective of this study was to identify and isolate lactic acid bacterial (LAB) strains from the intestinal tracts of pigs and feces of dogs and then characterize them as potential probiotics with antimicrobial activity against multidrug-resistant pathogenic bacteria. In a preliminary isolation screening, 45 of 1167 isolated LAB strains were found to have anti-S. aureus ATCC 27,735 activity. Using 16S rDNA and 16S-23S rDNA intergenic spacer region (ISR) sequences, five of these isolates were further identified as Lactobacillus animalis 30a-2, Lactobacillus reuteri 4-12E, Weissella cibaria C34, Lactococcus lactis 5-12H, and Lactococcus lactis 6-3H. Antimicrobial substance assays suggest that the L. lactis 5-12H, L. lactis 6-3H, L. animalis 30a-2, L. reuteri 4-12E, and W. cibaria C34 strains might produce bacteriocins and hydrogen peroxide (H2O2) as antimicrobial substances. The L. animalis 30a-2 and W. cibaria C34 strains were further characterized for probiotic properties and shown to have high acid and bile salt tolerance. Additionally, they have broad antimicrobial spectra, and can significantly repress the growth of all of the tested strains of MRSA isolates, some MDRAB, ESBL E. coli, and P. aeruginosa isolates, along with food-borne pathogenic bacteria such as Bacillus cereus ATCC 11778, Listeria monocytogens ATCC 19111, Salmonella spp., Shigella spp., and Yersinia enterocolitica BCRC 12986. This is the first report of H2O2-producing L. animalis 30a-2 and W. cibaria C34 isolated from the intestinal tracts of pigs and feces of dogs that have good antimicrobial activity against multidrug-resistant and food-borne pathogenic bacteria and have excellent probiotic properties.