In the context of industrial biotechnology, "fermentation" is a general term referring to processes which may utilize a variety of different microorganisms to transform different substrates to a wide variety of products, ranging from commodity chemicals and raw materials for industrial processing to value-added pharmaceuticals. Fermentations utilize a variety of different microorganisms, and may be anaerobic or aerobic. The Biofuels Research Laboratory maintains the capability to conduct aerobic and anaerobic fermentations at the flask, bench, and pilot scales, with the ability to conduct experiments ranging in scale from screening in microplates to conducting scale-up studies in a 150 liter reactor.
Enzyme Production - Through the use of genetically modified organisms, bacteria are grown and harvested to produce cellulase enzymes. Via fermentation, large batches of bacteria (upwards of 10 Liters plus) are grown. During this time, the cloned gene is active and the bacteria releases cellulases which are then purified through a series of purification methods. These techniques incorporate different uses of column chromatography and centrifugation. Also, by studying the mass balances of the fermentation reactions and changing different parameters, it is probable that more cost efficient fermentation trials will produce even more cellulase enzymes.
Ethanol Production - It is anticipated that the fermentation of cellulosic materials will present a more stressful environment to the fermenting organism than traditional starch-based fermentations. Process modeling conducted as part of our industrial ecology research suggests that the fermentation media will contain high solids content following pretreatment; it may also contain salts or other pretreatment byproducts which are inhibitory to fermentation. Our capability for fermentation experiments, in conjunction with the modeling efforts of our systems biology research, allows us to develop strategies to optimize media supplementation and organism selection to improve the performance of the yeast Saccharomyces cerevisiae in the challenging environment of cellulosic fermentation.
We are exploring the outcome of engineering membrane lipid composition, glycerol metabolism, and stress response in S. cerevisiae. High throughput screening is used to identify genetically engineered yeast strains that display certain phenotypes associated with improved ethanol tolerance. Following high throughput screening, select mutant strains can be assayed for ethanol tolerance and osmotolerance in larger scale fermentations designed to simulate industrial fermentation conditions in efforts to identify a more robust strain capable of increased ethanol production.
Hydrogen Production - Hydrogen is a third-generation fuel that can be produced from biomass and is naturally produced by many microbial species. The hyperthermophilic bacterium Thermotoga neapolitana is capable of fermenting a variety of sugars, including both hexoses and pentoses, to produce hydrogen gas. Fermentation experiments with T. neapolitana coupled to systems biology modeling of the organism's metabolic and regulatory network, should allow optimized hydrogen production in this species. It is also expected that experiments and theoretical studies with T. neapolitana may yield particularly interesting hypotheses due to the organism's hyperthermophilic nature and close evolutionary relationship to archaeal species (e.g. Pyrococcus furiosus).