L. plantarum and O. oeni strains were isolated and fermentation examined. L. plantarum was more efficient at MLF than O. oeni in Patagonian wines. Standardization of acclimation and inoculum was necessary for successful MLF by O. oeni. Acclimation in high ethanol content improved the malic acid consumption of O. oeni. MLF with L. plantarum strains required lower inocula and no pre-acclimation treatment.