Abstract
Serratia marcescens produces the red pigment prodigiosin and biosurfactant serrawettin at 30°C but not at 37°C. In an analytic study of the thermoregulation of S. marcescens 274, we noticed another temperature-dependent activity that was bacteriostatic to gram-negative and -positive bacterial species, at 37°C but not at 30°C. The thermo-insensitive isogenic mutant strain N0075 (a producer of prodigiosin and serrawettin even at 37°C) was devoid of such growth inhibitory activity. The revertant of strain N0075 made by transformation again exhibited the temperature-dependent mode of prodigiosin and serrawettin production, and bacteriostatic activity. This novel activity was correlated to the thermo-responsive acidification of the medium by S. marcescens. In response to higher environmental temperatures, S. marcescens seems to suppress its own growth and the growth of other bacteria.
