(635a) Comparison of General Metabolism of Rhizopus Oryzae Using Glycerol and Glucose As Carbon Sources Via Metabolic Flux Analysis

Crude glycerol is one of the main biodiesel waste streams. Effective utilization of the by-product glycerol can alleviate the environmental impacts of crude glycerol, and further improve substrate utilization efficiency of biofuels production. It has been reported that glycerol is a good carbon source for many microorganisms such as fungi and bacteria for value-added fuels and chemical production. Until now, two main routes for glycerol metabolism have been identified for eukaryotic micro-organisms. One route is that glycerol is phosphorylated first and subsequently dehydrogenated. The other is that glycerol is first oxidized by a NAD⁺-dependent dehydrogenase to dihydroxyacetone, and then phosphorylated. Both routes lead to glycolysis pathway to form pyruvate. In this study, we explore the utilization of glycerol in Rhizopus oryzaes. R. oryzae is a fungus that lives worldwide. Our preliminary results show that with crude glycerol as sole carbon resource, R. oryzae has higher biomass yield and lower lactic acid production compared with glucose or pyruvate growth cultures. However, less is known about the metabolism of glycerol utilization by R. oryzae. In this study, we focus on the investigation of glycerol metabolism in R. oryzae. Using a combined enzyme assays and ¹³C-isotopomer-labeling approaches, we examine the central metabolic pathways and quantify the flux distributions at pyruvate branch point. The knowledge obtained from this research provides important insights to the potential of novel fungal species for biotechnology applications.