Lactobacillus reuteri, A Member of the Gut Bacterial Flora: Studies on Antagonism, Metabolism and Genetics

摘要

Strains of the genus Lactobacillus, isolated from pig intestine, were characterized with physiological tests and DNA/DNA hybridization. L. acidophilus and L. reuteri were the dominating species identified among these strains. Using a novel method, the lactobacilli were screened for antimicrobial activity. The method employed Escherichia coli as target organism and beta-galactosidase synthesis as an indicator of growth inhibition. Resting cells of L. reuteri were found to produce a broad-spectrum antimicrobial substance from glycerol. The production of the substance, designated reuterin, occurred anaerobically with maximum production obtained at 37 C and pH 6-8. Reuterin production was significantly stimulated when the L. reuteri cells were in direct contact with other cells, such as E. coli. Reuterin, a mixture of the monomeric, hydrated monomeric and dimeric forms of 3-hydroxy-propionaldehyde (3-HPA), was shown to be an intermediate in the utilization of glycerol as an external electron acceptor during fermentation of carbohydrates by L. reuteri.