STUDIES ON THE CARBON CATABOLITE REPRESSION IN LACTIC ACID BACTERIA ISOLATED FROM WINE: CARBON CATABOLITE REPRESSION IN LACTIC ACID BACTERIA

In wine, lactic acid bacteria (LAB) are responsible for the bioconversion of malic acid to lactic acid, malolactic fermentation that mainly aims at reducing wine acidity. Two LAB strains isolated from the red wine microbiota (Oenococcus oeni 13-7 and Lactobacillus plantarum R1-1), were tested for their ability to exhibit the carbon catabolite repression (CCR) mechanism, that allows the rapid use of certain carbohydrates, over other carbon sources. Bacterial cells were inoculated in 0.1 M glycine buffer (pH 3.5), incubated at 30°C, with different carbohydrates (45 mM) and malic acid (45 mM). For both strains, the presence of glucose significantly inhibited malic acid metabolization (−60%), a similar effect being observed for galactose, mannose and maltose. The highest rate of malic acid conversion was shown in fructose/malate medium. Obtained results showed that malolactic strains can control the utilization of carbon sources via CCR, further studies being necessary to elucidate the mechanisms underlying this process.