Quantification of the influence of Trimethylamine-N-Oxide (TMAO) on the heat resistance of Escherichia coli K12 at lethal temperatures

AIM: To quantify the influence of trimethylamine-N-oxide (TMAO) on the heat resistance of Escherichia coli K12 MG1655 cells at static temperatures. METHODS AND RESULTS: Stationary-phase E. coli cells were inactivated at 52, 54 and 58°C. The heat resistance is described as reduction in the inactivation rate, k(max) , and/or an increase in the time for one decimal reduction, D, and/or an increase in the time for the fourth decimal reduction, t(4D) . CONCLUSIONS: Resistance of E. coli changed - increased - at all temperatures under study. Generally, the addition of TMAO to the growth medium protected E. coli cells, leading to an increase in their heat resistance, i.e. reduced k(max) and increased D and t(4D) values are obtained. SIGNIFICANCE AND IMPACT OF THE STUDY: Additional knowledge on the reaction of E. coli to heat in the presence of the organic osmolyte TMAO at lethal temperatures is provided. This work contributes to an improved understanding of the level of the resistance of bacteria to heat in the presence of osmolytes.