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 an d perform malolactic fermentation. To survive and grow in such a harsh envi ronment as wine, O. oeni uses several mechanisms of resistance including st ress protein synthesis. The molecular characterisation of three stress gene s hsp-18, clpX, trxA encoding for a small heat shock protein, an ATPase reg ulation component of ClpP protease and a thioredoxin, respectively, allow u s 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 expres sion of these genes as a function of growth is significantly different. Sur prisingly, the clpX gene, which is induced by heat shock, was highly expres sed in the early phase of growth. In addition to stress protein synthesis, adaptation to the acid pH of wine requires efficient cellular systems to ex trude protons. Using inhibitors specific for different types of ATPases, we demonstrated the existence of H+-ATPase and P-type ATPase. (C) 2000 Elsevi er Science B.V. All rights reserved.