Stress Response in Bacteria. Sub project no. 1: Stress stimulons in Lactococcus lactis

Bacteria respond to stress by induction of specific proteins in order to be able to grow or at least to increase survival. Exposure to sublethal stress conditions therefore usually increase the tolerance to higher levels of the same stress as well as to other stress conditions. In this project three stress forms are studied: glucose-starvation, phosphate-starvation and exposure to high levels of oxygen. The aim of the project is to investigate how these conditions affect the physiology of Lactococcus lactis, and how exposure to one stress form increases resistance to another. One major mile stone of this project is to identify the proteins induced by the stresses. This is being obtained by the use of the technique 2D gel electroforesis. Proteins which are induced by the stresses will be identified by N-terminal sequencing, and the genes encoding particularly interesting proteins will be identified. The importance of the proteins for the survival of Lactococcus lactis, and for the development of resistance to other stress forms, will be investigated. Furthermore, an analysis of the factors involved in regulation of expression of the genes will be performed.
A number of genes possibly involved in the response towards the stress forms under investigation are already known. Currently, mutational analyses of some these genes are being performed.