1,3-Propanediol:NAD+ oxidoreductases of Lactobacillus brevis and Lactobacillus buchneri

In the cofermentation of glycerol with a sugar by Lactobacillus brevis and Lactobacillus buchneri, a 1,3-propanediol:NAD+ oxidoreductase provides an additional method of NADH disposal. The enzyme has been purified from both L. brevis B22 and L. buchneri B190 and found to have properties very similar to those reported for the enzyme from Klebsiella pneumoniae. The enzymes required Mn2+ and are probably octamers with a molecular mass of 350 kDa. Although not absolutely specific for 1,3-propanediol when tested as dehydrogenases, the enzymes have less than 10% activity with glycerol, ethanol, and 1,2-propanediol. These properties contrast sharply with those of a protein isolated from another Lactobacillus species (L. reuteri) that ferments glycerol with glucose and previously designated a 1,3-propanediol dehydrogenase.