Fig. (3) Expressions of λclpQ⁺::lacZ⁺ in the wild-type and the various sigma- factor deficient strains. HY20001 (the wild-type), HY20005 (rpoS), HY20006 (rpoH) and HY20007 (rpoH rpoS) are as indicated at 30 °C or 42 °C. The lysogens were cultivated at 30 °C first for log growth and then shifted to 42 °C for 20 min.