REVIEW PAPER Lactobacillus: the Next Generation of Malolactic Fermentation Starter Cultures—an Overview Maret du Toit & Lynn Engelbrecht & Elda Lerm & Sibylle Krieger-Weber Received: 22 June 2010 / Accepted: 30 September 2010 / Published online: 16 October 2010 # Springer Science+Business Media, LLC 2010 Abstract Malolactic fermentation (MLF) is a secondary wine fermentation conducted by lactic acid bacteria (LAB). This fermentation is important in winemaking as it deacidifies the wine, it contributes to microbial stability and lastly it contributes to wine aroma through the production of metabolites. Oenococcus oeni is the main species used in commercially available starter culture currently, but research has indicated that different Lactoba- cillus species also partake in MLF and this has shifted the focus in the MLF field to evaluate the potential of lactobacilli as starter cultures for the future. There are 17 different species of Lactobacillus associated with wine- making either being associated with the grapes/beginning of alcoholic fermentation or the MLF and wine. Lactoba- cillus associated with wine is mainly facultative or obligatory heterofermentative and can withstand the harsh wine conditions such as high ethanol levels, low pH and temperatures and sulphur dioxide. Wine lactobacilli contain the malolactic enzyme encoding gene, but sequence homology shows that it clusters separate from O. oeni. Lactobacillus also possesses more enzyme encoding genes compared to O. oeni, important for the production of wine aroma compounds such as glycosidase, protease, esterase, phenolic acid decarboxylase and citrate lyase. Another characteristic associated with wine lactobacilli is the production of bacteriocins, especially plantaricins which would enable them to combat spoilage LAB. All these characteristics, together with their ability to conduct MLF just as efficiently as O. oeni, make them suitable for a new generation of MLF starter cultures. Keywords Lactobacillus . Wine . Malolactic fermentation . Starter cultures . Metabolism Introduction Winemaking is a complex process involving the interac- tion of different microbes. The two main groups of microorganisms involved are yeasts and bacteria. The yeasts and bacteria taking part in the fermentation can originate from grapes, the winery environment or as inoculated starter cultures. Yeasts are mainly responsible for the alcoholic fermentation, especially Saccharomyces cerevisiae, and contribute to the production of major aroma compounds such as esters, higher alcohols, alde- hydes and fatty acids. Yeasts, especially genera of the non- Saccharomyces group, can also be detrimental to wine quality by spoiling the wine through the production of haze, film layers or off-flavours. Malolactic fermentation (MLF) is a secondary fermen- tation that usually takes place during alcoholic fermentation or at the end of alcoholic fermentation and is carried out by one or more species of lactic acid bacteria (LAB). Four genera were identified as the principal organisms involved in winemaking: Lactobacillus, Leuconostoc, Oenococcus and Pediococcus. Of all the species of LAB, Oenococcus oeni is probably the best adapted to overcome the harsh environmental wine conditions and therefore represents the majority of commercial MLF starter cultures. Depending on M. du Toit (*) : L. Engelbrecht : E. Lerm Institute for Wine Biotechnology, Stellenbosch University, Private Bag X1, Matieland, 7602 Stellenbosch, South Africa e-mail: mdt@sun.ac.za S. Krieger-Weber Lallemand, In den Seite 53, 70825 Korntal-Münchingen, Germany Food Bioprocess Technol (2011) 4:876–906 DOI 10.1007/s11947-010-0448-8