The goal of this research project was to increase the total ethanol yield of Clostridium thermocellum. C. thermocellum is an anaerobic, thermophilic, cellulolytic and ethanogenic bacterium that utilizes cellobiose as a substrate to convert to ethanol. The advantage of growing these cells under high temperatures (60 oC) is that contamination factors are lessened as well as facilitating ethanol production.
An ethanol tolerant strain (S4M0) was developed in the laboratory with a 4% ethanol tolerance and was compared to the wild type strain (WT) under fed-batch conditions. Fed batch culture involves injecting the cells with medium during the stationary growth phase to prolong cell growth and produce more ethanol. Under normal batch conditions, the WT and S4M0 cells both produced around 1 g per liter of ethanol.