A comparative study of mannitol production by two lactic acid bacteria

Two different lactic acid bacteria, designated Lactobacillus sp. Y-107 and Leuconostoc sp. Y-002, were isolated during the fermentation of kimchi, a Korean fermented food product, and found to possess the capability of mannitol production. To optimize the culture conditions and compare the mannitol formation characteristics of the two strains, various fermentation conditions were investigated. Of several sugars tested, only fructose and sucrose were utilized as substrates for mannitol formation. With both strains, maximal mannitol production was obtained with fructose as the sole carbon source. Under the optimal culture conditions, the final mannitol concentrations produced by the Lactobacillus and Leuconostoc strains were 73 and 26 g/l from 100 g/l fructose with indicated yields of 86 and 65% based on the fructose consumed, respectively. Neither isolate produced other polyols such as glycerol and sorbitol as by-products. The two organisms exhibited very similar physiological behavior in mannitol biosynthesis apart from their metabolism of some sugars.