THE VITAMIN REQUIREMENTS OF LEUCONOSTOC FOR DEXTRAN SYNTHESIS

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Abstract
Raw sugar, molasses, etc. stimulate growth and dextran synthesis by Leuconostoc. Raw sugar contains most of the B-vitamins, hence growth and dextran formation by Leuconostoc in chemically defined media was studied. In a sucrose-amino acid medium it was found that no one of the vitamins, thiamine, riboflavin, nicotinic acid, pantothenic acid, biotin, pyridoxal, pyridoxamine, folic acid or p-aminobenzoic acid, was uniquely essential to dextran synthesis. All strains of L. mesenteroides and L. dextranicum used required thiamine, nicotinic acid and pantothenic acid for growth. By measuring growth and dextran formation at various levels by these 3 vitamins it was found that increasing concns. inhibited the organisms; hence raw sugar does not function as an auxiliary source of these vitamins. The vitamin requirements of Leuconostoc were also detd. in glucose and fructose media; in these media, as contrasted to sucrose medium, the organisms required biotin for growth.