Improving Fermentation by Product Removal

Abstract

Fermentation processes are often used in industrial biotechnology to produce compounds that can be used as fuels, bulk and fine chemicals, food and feed ingredients, and pharmaceuticals. In these processes, microorganisms convert a substrate - most commonly sugars - into the target product in bioreactors operating in batch, fed-batch or, in a few cases, continuous mode. Many microbial products, however, inhibit the production, are toxic to the microorganism or are chemically unstable at the fermentation conditions. These processes benefit from product recovery during fermentation, also called In Situ Product Recovery or In Situ Product Removal (ISPR), through yield and productivity enhancement and potential cost reduction. Many proof-of-concepts have been described in the scientific literature for a broad array of products, microorganisms and recovery methods, and a few ISPR processes have been reported at industrial scale. ISPR approaches are currently being extended to microbial products that, although not hindered by inhibition, toxicity or degradation, would benefit of uncoupling the residence times of product, microbial cells and aqueous phase. In this chapter the state of the art of ISPR is discussed, with an emphasis on process design considerations.