Quantifying degradation product concentrations in the hydrolysate before and after fermentation during the RaBIT (Rapid Bioconversion with Integrated recycling Technology) process was studied first. The RaBIT process uses high biocatalyst concentrations and biocatalyst recycling to dramatically reduce enzymatic hydrolysis and fermentation times and also enzyme costs. Results from this study showed an incomplete mass balance between vanillin and its metabolites suggesting an accumulation of vanillin inside the cells. Vanillin is known to disrupt cellular membranes and may be a chief cause for decreased performance when yeast are recycled. Testing of this hypothesis is underway.
To overcome the effects of degradation products on the fermentation, several changes have been implemented in the RaBIT process. Positive results have been obtained by changing the process time, the process type, and by using a cell separation technique.
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