3.1.3. Temperature

In wine, the optimum temperature of growth is di fferent from what is obtained in laboratory culture. The optimum range is dependent on other physical and chemical parameters of the wine, notably the ethanol content. A higher ethanol content will lead to a decrease in the optimum growth temperature. In general, MLF usually occurs at sub-optimal LAB temperatures (below or around 18 ◦C). At 15 ◦C or lower, the chance of bacterial growth is slight [38]. Guerzoni et al. [36] studied the e ffects of several chemico-physical factors (pH, SO2, ethanol concentration and temperature) on *L. plantarum* and *O. oeni*. A temperature increase only positively a ffected the lag phase of *O. oeni*, but not of *L. plantarum*. A temperature increase exhibited a negative and positive influence on *O. oeni* and *L. plantarum*, respectively. The combination of high temperatures and high alcohol increase the toxicity of ethanol as outlined above. Low temperatures are not lethal but decrease the enzymatic activity.
