Evolutionary Adaptation by Repetitive Long-Term Cultivation with Gradual Increase in Temperature for Acquiring Multi-Stress Tolerance and High Ethanol Productivity in DMKU 3-1042.

During ethanol fermentation, yeast cells are exposed to various stresses that have negative effects on cell growth, cell survival, and fermentation ability. This study, therefore, aims to develop -adapted strains that are multi-stress tolerant and to increase ethanol production at high temperatures through a novel evolutionary adaptation procedure. DMKU 3-1042 was subjected to repetitive long-term cultivation with gradual increases in temperature (RLCGT), which exposed cells to various stresses, including high temperatures.

Distinct Metabolic Flow in Response to Temperature in Thermotolerant Kluyveromyces marxianus.

The intrinsic mechanism of the thermotolerance of Kluyveromyces marxianus was investigated by comparison of its physiological and metabolic properties at high and low temperatures. After glucose consumption, the conversion of ethanol to acetic acid became gradually prominent only at a high temperature (45°C) and eventually caused a decline in viability, which was prevented by exogenous glutathione. Distinct levels of reactive oxygen species (ROS), glutathione, and NADPH suggest a greater accumulation of ROS and enhanced ROS-scavenging activity at a high temperature.

Selection of thermotolerant Saccharomyces cerevisiae for high temperature ethanol production from molasses and increasing ethanol production by strain improvement.

A thermotolerant ethanol fermenting yeast strain is a key requirement for effective ethanol production at high temperature. This work aimed to select a thermotolerant yeast producing a high ethanol concentration from molasses and increasing its ethanol production by mutagenesis. Saccharomyces cerevisiae DMKU 3-S087 was selected from 168 ethanol producing strains because it produced the highest ethanol concentration from molasses at 40 °C.