(254a) Assessing the Metabolic Capabilities of the Yeast Issatchenkia Orientalis SD108 and Its Application to Biochemical Production (Faculty Candidate)

Many platform chemicals can be produced from renewable biomass by microorganisms, with organic acids making up a large number of these chemicals. Intolerance to the resulting low pH growth conditions, however, remains a challenge for the industrial production of organic acids by microorganisms. The yeast Issatchenkia orientalis SD108 is a promising host for industrial production because it is tolerant of low pH conditions. Here, we explore the carbon substrate utilization capacity of I. orientalis SD108 by quantitatively measuring growth rates. To systematically assess the metabolic capabilities of this non-model organism, we develop a genome-scale metabolic model for I. orientalis SD108 spanning 850 genes, 1,825 reactions, and 1,700 metabolites. In order to improve the quantitative predictions of the model, organism-specific macromolecular composition and ATP maintenance requirements were estimated from experimental data generated as part of this study by making use of chemostat data performed under carbon limited growth conditions. We examine the metabolic network’s topology, including essential genes, and draw comparisons with Saccharomyces cerevisiae. We also employ the model to survey the growth impact of targeted gene deletions and compare to in vivoresults we obtained using a CRISPR/cas system. Next, we propose and investigate production pathways for succinic acid through the use of the OptKnock framework to discern knockouts which link production of the targeted chemical to biomass production. Finally, we discuss implications for other industrially-relevant organic acids.