Thermophilic bacteria colony growth and its consequences in the food industry

The growth kinetics of thermophilic bacteria Bacillus acidocaldarius (CCM 3497), Bacillus stearothermophilus (CCMI 237), Thermus aquaticus (CCM 3488), Thermus ruber (CCM 4212), and Thermus species (CCM 4199) on solid media were studied in the temperature range of 40-60degreesC. The behaviour of bacterial colonies on agar plates was recorded with a digital camera during 160 hours of experiment. The growth of colony diameter was found to be linear with time at lower temperatures and an acceleration of the growth with time at suboptimal growth temperature 60degreesC was observed. A simple mathematical model describing the effect of irregular colony growth pattern on its rim can elucidate this unusual phenomenon.