Determination of specific metabolic and morphological adaptations in L. plantarum and the cross-protective effects of ethanol exposure toward other environmental stresses complemented the transcriptome-based results. In addition, mutagenesis approaches revealed that the molecular adaptations are at least partly controlled by CtsR, as previous studies revealed the direct interaction between CtsR and the promoter regions of the ctsR-clpC operon and hsp1 gene (16).