Inhibition of enterotoxigenic Escherichia coli K88, K99 and 987P by the Lactobacillus isolates from porcine intestine

Thirty-six Lactobacillus strains were isolated from the small intestine of piglets and 14 of them were chosen as they had a good ability (> 5 bacteria per cell) to attach to the epithelial cells of the small intestine. They were selected to investigate the antagonistic effects against enterotoxigenic Escherichia coli (ETEC) including K88ab, K88ac, K88 + MB (a local strain of haemolytic (H) ETEC K88 + bacterium from Manitoba, Canada), K99 and 987P. Their effects on the adhesion of E coil K88 + MB and K88ac to the intestinal mucus of piglets were also studied. The results indicated that six out of the 14 Lactobacillus isolates were able to moderately or strongly inhibit the growth of eight strains of ETEC through the production of organic acids, but not by bacteriocin or hydrogen peroxide. Well diffusion assays of the major organic acids of the Lactobacillus culture supernatants showed that both acetic acid and lactic acid inhibited the growth of E coli. Lactobacillus isolates did not affect the attachment of E coli K88 + MB and K88ac to the small intestinal mucus of piglet. (C) 2000 Society of Chemical Industry.