IS THERMOTOLERANCE CORRELATED TO HEAT-SHOCK PROTEIN-SYNTHESIS IN LACTOCOCCUS-LACTIS SUBSP-LACTIS

Exposure of Lactococcus lactis subsp. lactis cells to a heat shock at 40-degrees-C for 30 min induces thermotolerance, the increased ability of bacterial cells to survive exposure to lethal temperature (52-degrees-C for 25 min). This transient state of thermal resistance is accompanied, as in Escherichia coli, by the synthesis of a new set of specific proteins termed heat-shock proteins (Hsps). Pre-treatment of the bacterial cells by antibiotics (streptomycin, spiramycin, kanamycin and erythromycin) known to act on translation, induces the major Hsps synthesis but no thermal protection; conversely, puromycin and amino acid analogues treatments, known to produce abnormal and incomplete peptides, triggers the thermotolerance state without inducing significant Hsps synthesis. These results demonstrate that heat-shock response and induced thermotolerance are not tightly correlated phenomena in L. lactis subsp. lactis.