Comparison of ethanol and temperature tolerance of Zymomonas mobilis strain in glucose and molasses medium

The effect of temperature and exogenous ethanol was evaluated on the ethanol production potential of Zymomonas mobilis MTCC 2428 as an alternative to the classic and widespread use of Saccharomyces cerevisiae . At 30 °C, this strain produced the maximum amounts of ethanol, i.e. 4.0 and 3.3% (v/v) after utilizing 98 and 83% (w/v) sugar on glucose and molasses medium, respectively. While at higher temperatures (35 & 40 °C), the ethanol production by the strain decreased. Moreover, the strain was able to operate in the presence of 8% (v/v) ethanol in glucose medium at 30 °C; whereas it tolerated only 6 and 2% (v/v) ethanol at 35 and 40 °C, respectively. At the respective temperatures, further higher concentrations of the supplemented ethanol were found to be inhibitory to the isolate.