Regulation of stress response in Oenococcus oeni as a function of environmental changes and growth phase.

Oenococcus oeni is a lactic acid bacterium which is able to grow in wine and perform malolactic fermentation. To survive and grow in such a harsh environment as wine, O. oeni uses several mechanisms of resistance including stress protein synthesis. The molecular characterisation of three stress genes hsp18, clpX, trxA encoding for a small heat shock protein, an ATPase regulation component of ClpP protease and a thioredoxin, respectively, allow us to suggest the existence in O. oeni of multiple regulation mechanisms as is the case in Bacillus subtilis. One common feature of these genes is that they are expressed under the control of housekeeping promoters. The expression of these genes as a function of growth is significantly different. Surprisingly, the clpX gene, which is induced by heat shock, was highly expressed in the early phase of growth. In addition to stress protein synthesis, adaptation to the acid pH of wine requires efficient cellular systems to extrude protons. Using inhibitors specific for different types of ATPases, we demonstrated the existence of H+-ATPase and P-type ATPase.