Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/19/2009
Publication Date: 11/19/2009
Citation: Skory, C.D., Hector, R.E., Gorsich, S.W., Rich, J.O. 2009. Enhanced Production of Carboxylic Acids by Engineering of Rhizopus [abstract]. Interpretive Summary:
Technical Abstract: The fungus Rhizopus is frequently used to convert, or ferment sugars obtained from agricultural crops to lactic acid. This natural product has long been utilized by the food industry as an additive for preservation, flavor, and acidity. Additionally, it is used for the manufacture of environmentally friendly products which include the biodegradable plastic, poly-lactic acid (PLA), and the chlorine-free solvent, ethyl lactate. In order to allow the market potential of lactic acid to continue expanding at the current rapid pace, it is important that the production costs are minimized by the development of new and improved technologies. Our laboratory has developed numerous techniques for the genetic modification of Rhizopus. We have genetically modified R. oryzae strains to overproduce lactate dehydrogenase, an enzyme critical in the synthesis of lactic acid, resulting in considerably higher lactic acid productivity with lower amounts of unwanted by-products. Additionally, we have studied numerous monocarboxylic acid transporters involved in the export of lactic acid and developed strategies to minimize end-product inhibition by cellular acidification. These techniques have involved genomic analyses for metabolic engineering, the over-expression of native genes, and inhibition of unwanted pathways such as ethanol production, through RNA inhibition and gene deletion of pyruvate decarboxylase. Continued efforts towards the development of improved technologies for producing lactic acid will be presented.