Project Number
IWBT-B 08-08
Project title
Assessing malolactic fermentation under winemaking conditions
Project leader
Divol, B
Institution
University of Stellenbosch. Faculty of AgriSciences. Institute for Wine Biotechnology
Team members
Du Toit, M
Divol, B
Mtshali, S
Project description
Malolactic fermentation is a key step of winemaking. It is conducted since late 19th century in a few European regions and interpretation of the phenomenon was established in the 1920’s in Burgundy and 1930’s in Bordeaux, France. Malolactic fermentation is mainly conducted by the lactic acid bacterium Oenococcus oeni in order to decrease wine acidity though the biotransformation of L-malic acid in L-acetic acid. This biochemical reaction involves the malolactic enzyme (mleA), NAD+ and Mn2+ being used as cofactors. In spite of the availability of the nucleotide sequence of the enzyme encoding gene in the databases, the regulation of mleA remains poorly understood. In particular, the adaptation of Oenococcus oeni to the wines originated from warm climates (such as South Africa) has not been studied yet.
This project deals with the evaluation of commercial malolactic starter cultures (all originally isolated in the northern hemisphere) for warm climate wine conditions (i.e. mostly with low malic acid concentration, but high ethanol content and high pH). The impact of these specific enological conditions will then specifically be tested in regard to the regulation of the mleA gene. We aim to demonstrate a potential link between quick adaptation of malolactic fermentation completion and high expression of the mleA gene.
Presentation(s)
Du Toit, M, Mtshali, S, Knoll, C & Divol, B. 2008. Genetic screening of wine lactic acid bacteria for enzyme encoding genes important in winemaking. 9th Symposium on Lactic Acid and Bacteria, Egmond aan Zee, The Netherlands.
Mtshali, P S, Divol, B T & Du Toit, M. 2010. Genetic characterisation of Lactobacillus lindneri strains isolated from South African grapes and wine. 4th International Congress of the South African Society for Enology and Viticulture, Cape Town, South Africa, November.
Mtshali, P A, Divol, B & Du Toit, M. 2010. Comparative analysis of genes coding for enzyme of enological relevance in wine lactic acid bacteria. 4th International Congress of the South African Society for Enology and Viticulture, Cape Town, South Africa, November.
Article
Du Toit, M, Mtshali, P S, Knoll, C, Divol, B. 2008. Genetic screening of wine lactic acid bacteria for enzyme encoding genes important in winemaking, Food Microbiology, v. 25 (8) (p. 983-991)
Miller, B J, Franz, C M A P, Cho, G-S, Du Toit, M. 2011. Expression of the malolactic enzyme gene (mle) from Lactobacillus plantarum under winemaking conditions, Current Microbiology, v. 62 (p. 1682-1688)
Malherbe, S, Tredoux, A G J, Nieuwoudt, H H, Du Toit, M. 2012. Comparative metabolic profiling to investigate the contribution of O. oeni malolactic fermentation starter cultures to red wine composition, Journal of Industrial Microbiology and Biotechnology, v. 39 (p. 477-494)