Extractive Fermentation Employing Adsorbent Resin to Enhance Production of Metabolites Subject to Product or Byproduct Inhibition

Abstract

Feedback inhibition is a common problem during fermentation process when the concentration of the end product reaches a certain level. The excessive accumulation of byproducts in the culture may also inhibit growth of cell and repress the secretion of the target metabolite. Integration of fermentation and separation of fermentative products or byproducts is the possible approach to be used industrially to reduce product or byproduct inhibition aim at enhancement of fermentation performance. Production of many antibiotics, amino acids and fungal metabolites are subject to feedback inhibition, where the problem shall be reduced to enhance the product yield. On the other hand, production of some metabolites by microorganisms, such as lactic acid bacteria and recombinant bacteria, are subject to byproduct inhibition. In recent years, commercial production of proteins and metabolites from microbial fermentation for industrial applications has increased significantly. Innovative fermentation shall be developed to replace the conventional methods to ensure that the process is economically viable and the price of products become competitive. To overcome the problem related to feedback repression and the accumulation of the undesirable by-products in the culture, many strategies such as genetic modification, application of fed-batch fermentation, adsorptive membranes, electrodialysis and macroporous ion-exchange resins have been proposed. Inclusion of macroporous adsorbent resin in the culture in combination with effective fermentation may be used as effective approaches to reduce feedback inhibition or to reduce the accumulation of repressive byproducts. This, will in turn, may increase the product yield.