Heat shock induces thermotolerance and inhibition of lysis in a lysogenic strain of Lactococcus lactis

Abstract

In this preliminary work, the heat shock response of lactic acid bacteria was investigated and characterized. Log-phase Lactococcus lactis cells pre-incubated at 40°C before heat challenge at 52°C for 30 min demonstrated increased thermotolerance as compared with cells pre-incubated at 30°C. The response persisted for at least 60 min. Additionally, we demonstrated that: (i) the physiological expression of the heat shock response is temperature dependent; (ii) ethanol 4.0% (v/v) caused, to a lesser extent, a response similar to the heat shock; and (iii) hydrogen peroxyde failed to induce a detectable response. Furthermore, we suggest that the induction of the heat shock response increases the resistance of a lysogenic strain of L. lactis, treated by mitomycin C (1.25 μg/ml), to lysis by the bacteriophage.