Isolation of a high potential thermotolerant strain of zymomonas mobilis for ethanol production at high temperature using ethyl methane sulfonate mutagenesis
The wild-type strain Zymomonas mobilis TISTR548 has a critical temperature for its
growth and ethanol production at 38 C. To obtain a high potential thermotolerant strain of
this ethanologenic bacterium, this wild-type strain was subjected to chemical mutagenesis
using ethyl methane sulfonate (EMS). After EMS treatment, the mutagenized cells were screened
at temperatures ranging from 38 to 40 C. The results showed that only six mutant strains,
designated ZM EMS-52, ZM EMS-121, ZM EMS-143, ZM EMS-229, ZM EMS-263
and ZM EMS-297, could grow and produce a relatively high level of ethanol at 40 C.
Among these mutants, ZM EMS-229 displayed higher growth and ethanol production
capacity than did the wild-type and other mutants at 37 and 40 C. This mutant strain also
showed greater resistance to high concentrations of ethanol, acetic acid and H2O2 at high
temperature than did the wild-type. These findings suggested that the ZM EMS-229 was a
good candidate for high-temperature ethanol fermentation.