The metabolism of several carboxylic acids by lactic acid bacteria

The anaerobic metabolism of citrate, fumarate, gluconate, malate, 2-oxoglutarate and pyruvate by 137 strains of 23 species of lactic acid bacteria was investigated. The bacteria were from various sources (plant material, meat and dairy products, dough and wine) and belonged to the genera Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus. The ability of metabolize the acids was determined by thin layer chromatography or by enzymatic analysis after growth of the strains in a glucose-containing medium. All strains metabolized pyruvate and only 12 mainly heterofermentative strains were malate negative. These strains were also unable to decompose citrate. This acid was fermented by 23 strains, all of which metabolized malate. Many lactic acid bacteria reduced 2-oxoglutarate to hydroxyglutarate. The strains of Lactobacillus plantarum did not metabolize 2-oxoglutarate whereas all strains of Leuconostoc oenos decarboxylated this acid and formed 4-hydroxybutyrate and succinate. Gluconate was fermented by 52 mainly heterofermentative strains. No correlation was observed between the ability to ferment citrate, malate or gluconate.