Metabolism of sugars and organic acids by lactic acid bacteria from wine and must

Abstract

The energy metabolism of Oenococcus oeni and of some other lactic acid bacteria from wine using sugars and organic acids is discussed. O. oeni is a heterofermentative lactic acid bacterium degrading hexoses by the phosphoketolase pathway. Reoxidation of NAD(P)H by acetyl-P (or acetyl-CoA) in the ethanol pathway represents a limiting step of the pathway. O. oeni varies the classical phosphoketolase pathway to bypass this step by the formation of erythritol. Substrates like fructose, pyruvate, citrate (as a source of pyruvate) and O2 are used additionally or preferred acceptors for NAD(P) reoxidation. As a consequence, acetyl-P is excreted as acetate. The growth rate of the bacteria increases when the limiting ethanol pathway is by-passed. In addition, O. oeni ferments organic acids (citrate, malate and pyruvate), but only pyruvate supports growth when present as the sole substrate. Some other strains of lactic acid bacteria are able to metabolize L-tartrate and fumarate. The metabolic routes and their significance are described. © 2009 Springer-Verlag Berlin Heidelberg. All rights reserved.