Application of MALDI-TOF-MS and nested SAPD-PCR for discrimination of Oenococcus oeni isolates at the strain level

Oenococcus oeni is the most important lactic acid bacterium during vinification and is frequently used as a commercial starter culture for malolactic fermentation. Since different strains exhibit a high heterogeneity concerning wine-related physiological characteristics, reliable methods for their differentiation at the strain level are needed, especially for the development of starter cultures. Microbial identification by using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has increased over the last few years. In the present study, we used MALDI-TOF-MS for the differentiation of 11 O. oeni isolates originating from 5 different wine-growing regions. Furthermore, these strains were analyzed by a DNA fingerprinting method (nested specifically amplified polymorphic DNA (nSAPD)-PCR). Both methods supplied fast and reproducible results allowing a reliable differentiation of the O. oeni strains studied. MALDI-TOF-MS showed a slightly higher discriminatory ability, since two genetically very similar strains could be separated only by the application of this technique. However, nSAPD-PCR and the subsequent cluster analysis permitted a correlation between genetic similarities and the geographical origin of the strains.