Barotolerance is inducible by preincubation under hydrostatic pressure, cold-, osmotic- and acid-stress conditions in Lactobacillus sanfranciscensis DSM 20451T


M.A. Ehrmann, Lehrstuhl für Technische Mikrobiologie, Technische Universität München, 85350 Freising, Germany


Aims:  This study addresses the inducibility of barotolerance by preincubation of Lactobacillus sanfranciscensis DSM 20451T under various sublethal stress conditions.

Methods and Results:  Stress conditions which reduce the growth rate of L. sanfranciscensis DSM 20451T to 10% of its maximum were determined. These conditions were met at 43, 12·5°C, a pH value of 3·7, 1·9% NaCl, or 80 MPa respectively. In contrast to heat preincubation, other prestresses, including salt, cold and pressure led to an increase of barotolerance by hydrostatic pressure of 300 MPa for 30 min. Stationary-phase cells also showed an increased barotolerance. Sublethal pressure leads to enhanced heat tolerance.

Conclusions:  Stress response to salt, low temperature and acidic pH as well as starvation overlap with that one to high pressure by inducing barotolerance.

Significance and Impact of the Study:  Inactivation of bacteria by high pressure treatment is influenced by their history which modulates barotolerance. Mechanisms of barotolerance appear different from heat shock defence.