Some physiological effects of near-maximum growth temperatures on an obligately psychrophilic marine bacterium.

The heat inactivation of the obligately psychrophilic marine bacterium Ant-300 was investigated in terms of glucose uptake, the oxidation of glucose to CO2, and permeability control. At 13C, the maximum temperature for growth, and at slightly higher temperatures, CO2 evolution decreased with time during the oxidation of exogenously supplied glucose. The decrease in CO2 evolution appeared to be a result of heat-induced restrictions on glucose uptake. Leakage of intracellular metabolites apparently contributed to the cells decreased ability to take up glucose at elevated temperatures. A consequence of these heat-induced changes seemed to be the acceleration of cell starvation.