Evaluation of the settling of malolactic starters within the indigenous microflora of wines

Abstract

Six malolactic starters were experimented. The objective was an evaluation of the capacity of each one to settle in different wines. First we obtained the genomie DNA fingerprinting with Not I a rare cutting enzyme after pulse field gel electrophoresis (PFGE). Previous results with Leuconostoc oenos strains of our collection showed that this enzyme was the most appropriated for identification at the strain level. However, we did not obtain six different patterns, three starters showed the same. Therefore Apa I and Sfi I patterns were also established. Contrary to the expected results A, B and C finally had the same fingerprinting with the three enzymes. Another investigation was conduced using the Southem hybridization of EcoRI restricted DNA with the φMC10 prophage DNA as probe. Our again all three starters showed the same pattern. They probably were prepared with the same strain. Wines in vat or barrels were inoculated just after racking. Malolactic fermentation had already begun in some of them before inoculation. However malic acid was degraded more quickly in all the inoculated wines than in the controls. The PFGE patterns were obtained from bacteria isolated from wines at the end of malolactic fermentation. In 15 cases of 21, the pattern of the starter appeared alone or superimposed with other bacteria. This proved that, even in the worst conditions of this experimentation, where the indigenous microflora was very abundant and active malolactic starters could survive and predominate. The influence of these starters on the sensorial quality of wines needs to be studied.