Fig. 4

Comparison of MV production between wild and mutant strains at 55 °C or 60 °C with different cultivation times (48, 96, and 144 h) using fluorescent reagent DiI (A) or FM4-64 (B). Culture supernatants were obtained from the culture incubating at 55 °C or 60 °C at different times (h) and the samples were prepared by following the methods as described in the Materials and methods section. The data were calculated as values relative to that of the wild strain at 48 h and are represented by error bars as the average of two (55 °C cultivation) or three (60 °C cultivation) independent measurements. Student's t-tests were used to evaluate the increase in MV production as compared with the value of the wild strain at 60 °C for 48 h (**, P < 0.01). A and B, the wild strain of H328 at 55 °C after preincubation at 55 °C overnight (); the wild strain of H328 at 60 °C after preincubation at 60 °C overnight (); ∆degP mutant strain at 55 °C after preincubation at 55 °C overnight (); ∆degP mutant strain at 60 °C after preincubation for 15 h at 57 °C and then 48 h at 60 °C ()