关键词: 乳杆菌；双歧杆菌；碳水化合物；发酵；益生元

Abstract: The growth of twelve Lactobacillus strains and six Bifidobacterium strains on a medium containing 13 carbohydrates including prebiotics (fructooligosaccharide (FOS), FOS (Vilof), xylooligosaccharide (XOS), galactooligosaccharide (GOS), short-chain inulin, long-chain inulin, isomalto oligosaccharide (IMO), stachyose, resistant dextrin, polydextrose, L-arabinose, lactitol, and erythritol) as sole carbon sources was compared using lactose as a control. Optical density at 600 nm (OD600 nm) and pH were recorded after 24 and 72 h of culture. Results showed great differences in the growth of strains on different carbohydrates. Resistant dextrin, polydextrose, and erythritol showed very limited growth promotion effects on all the strains after 24 h, probably because these strains lack the enzymes that hydrolyze glycosidic bonds. The growth promotion effects of FOS, XOS, GOS, inulin, stachyose, L-arabinose and lactitol were strain specific, presumably because of the different extracellular or intracellular enzymes secreted by each strain. Long-chain inulin slowed down the fermentation of Lactobacillus acidophilus, but was not applicable to the other strains. Despite being derived from the same source, the FOS from different manufactures showed different effects on the fermentation characteristics of strains, presumably because of the different contents of impurities they had. It was postulated that some prebiotics are beneficial to human health not by directly working on promoting the growth of lactobacilli or bifidobacteria in vivo; instead, they are degraded by other bacteria in the gut before being utilized by probiotic strains.

Key words: lactobacilli; bifidobacteria; carbohydrates; fermentation; prebiotics