Low temperature inhibition on binding,transport, and incorporation of leucine,arginine, methionine,and histidine in Escherichia coli

A multiple amino acid auxotroph and a wild type of Escherichia coli K12 were used to study the effects of near minimum growth temperatures on the binding, transport, and cellular incorporation of selected amino acids. Both strains of the bacterium showed the same minimum growth temperature (8°C) when previously grown at 15°C. At 8°C and above, the auxotroph exhibited an overall greater ability to bind and transport amino acids than did the wild type. Below the minimum growth temperature, transport and cellular incorporation including respiration (uptake) were significantly lower for either organism. The NEU and HEPPEL osmotic shock treatment indicated the removal of the specific histidine-binding protein and the ability to bind histidine was not recovered by further incubation below 8°C. At 8°C and above, the cells recovered their ability to bind histidine within one hour. The evidence presented indicates a direct relationship between the auxotroph's minimum growth temperature and its ability to bind amino acids, specifically methionine.