Fermentation

Being Selective and Specific

From Fermentable Sugars to Value-Added Precursors

Fermentation is a vital unit operation in the biomass conversion process offering the potential for complete utilization of biomass into multiple bioproducts.  Of special interest in biorefining are platform intermediate chemicals from fermentation that can be converted into numerous consumer and industrial products, including succinic acid and butanol.

At ABPDU our focus is on biological fermentation as it offers the most selectivity and specificity when it comes to producing a product or intermediate. Microorganisms and recombinant organisms are used to metabolize lignocellulosic sugars and other intermediates to form a wide array of alcohols, acids, and enzymes—precursors to biofuels, biochemicals, and biomaterials.

High Yields Depend on Extensive Process Development

While fermentation is a very well understood unit operation in first-generation biofuels and bioproducts, it is a relatively new process area in the conversion of lignocellulosic sugars. Achieving high yields and economic viability requires extensive process development.

We apply process intensification and integration concepts to the traditionally removed fermentation and product recovery steps. Our intricate fermentation systems integrate either into deconstruction or recovery to assess the viability and economics of the integrated processes at a relevant scale.

Concept Development and Scale Up

Some companies design their pathway and select the organism to obtain a particular molecule. Based on your specifications, we can develop the fermentation process to a point where it is stable and ready for scale up.

Process Optimization and Validation

If you have a completely optimized bench scale fermentation process, we can control and optimize the process and then demonstrate it at a larger scale.

Achieving End Product Specifications

Feedstock can represent >40% of all process costs in a biomass-to-bioproduct process. Therefore, it is critical to rapidly and efficiently metabolize sugars and other molecules from biomass.

In designing a successful fermentation process, the required end product or intermediate drives our decision-making. Analytical chemistry is an essential part of our fermentation process development, enabling, among other things:

  •  Tight control of process parameters such as temperature, pH balance, nutrients, etc.
  • Optimum selection of microorganisms and fermentation methods
  • Improved product concentration
  • Control of inhibitory effects for better process integration

Our Equipment

Fermentation Process Options

 

Environments
Aerobic and anaerobic fermentations in batch, fed-batch, and continuous modes.
Simultaneous Sachcharification
In simultaneous saccharification (SSF), the fermenting microorganism simultaneously consumes the released sugars from enzymatic hydrolysis, avoiding product inhibition of enzymes and also decreasing the probability of contamination.
Co-Fermentation
There are substantially greater savings in capital and operating costs to be gained by applying a co-fermentation process in which the hexose and pentose sugars derived from both the cellulose and hemicellulose fractions are simultaneously fermented to bio-product in a single operation. Using genetically modified organisms or a community of organisms, this method metabolizes more than one molecule at the same time, e.g glucose-6 carbon, xylose-5 carbon, and lignin.
Simultaneous Sachcharification and Co-Fermentation
Enzymatic hydrolysis can be performed simultaneously with the co-fermentation of glucose and xylose in a process referred to as simultaneous saccharification and co-fermentation (SScF). Besides reduced capital cost, the SScF process offers several advantages, which include continuous removal of end-products of enzymatic hydrolysis that inhibit cellulases or β-glucosidases and higher ethanol productivity and yield than separate hydrolysis and fermentation.
Consolidated Bio Processing
Consolidated bioprocessing (CBP) approaches combine enzyme production, substrate hydrolysis, and fermentation into one process. CBP has potential to lower the cost of biomass processing compared to process configurations featuring a dedicated step for cellulase production due to the elimination of operating and capital costs associated with dedicated enzyme production and more effective biomass solubilization.

Related Papers and Publications

Demonstrating Bisabolene Production at 1.8 L Scale

Bisabolane has been identified as a potential biosynthetic alternative to D2 diesel fuel. Researchers at JBEI have engineered S. Cerevisiae for the production of bisabolene, bisabolane’s immediate precursor, by the introduction of bisabolene synthase from A. Grandis.

Using FT-NIR to Facilitate Dynamic Fed-Batch Fermentations

Fed-batch fermentations involve controlled feeding of a growth limiting nutrient to a batch culture enabling higher cell densities. Some classic fed-batch strategies employ pH, OUR (oxygen uptake rate), DO (Dissolved oxygen) etc, as control parameters, based on their indirect correlations with growth.