Biofuels Production projects

Development of an Oleaginous Yeast Model System

Several oleaginous yeast (Rhodosporidium toruloides, Lipomyces spp., Yarrowia lipo/ytica) are being studied to compare their genetic tractability and lipid productivities. The goal of the project is to identify the best strain for carrying out detailed functional genomic, QTL mapping, and metabolic engineering studies to make fatty acid-derived diesel-like fuels in oleaginous yeast. The team seeks to understand why oleaginous yeast exhibit high flux from glucose to fatty acids. This knowledge will also be used to improve advanced biofuel yields in other yeast hosts, such as Saccharomyces cerevisiae (started in 2012).

project Highlights

2013 Highlights

Our initial goal was to choose the "best" oleaginous system for further study. We obtained a diverse collection of oleaginous yeast isolates from public culture collections. All of these yeast isolates were able to accumulate large amounts of lipids after nitrogen starvation and preliminary microscopy confirmed the presence of lipid bodies. We chose to focus on Rhodosporidium toruloides for production of diesel-like fuels. In the process, we a) developed fluorescent methods to quantify lipid production, b) focused on five R. toruloides strains for comparative genomics, and c) began to build a basic genetic toolbox to perform genetic screens, engineer the genome, and perform functional genomic studies.

2012 Highlights

Oleaginous yeast naturally produces large amounts of lipids, when starved for nitrogen, which could serve as a production host for diesel-like biofuels. However, there are currently two major hurdles: 1) these organisms require oxygen for growth, and commercial-scale biofuel processes are likely to be anaerobic, or oxygen-free; and 2) few genetic tools exist for metabolic engineering oleaginous yeast. We have initiated a project to develop genetic tools for Rhodosporidium toruloides. Our goal is to use high-throughput genetics, combined with fluorescence-based screens, to understand why oleaginous yeast are able to produce such large amounts of lipids compared to non-oleaginous yeast such as Saccharomyces cerevisiae. We have obtained a diverse collection of natural R. toruloides isolates from around the world and are screening these strains for differences in lipid production using fluorescent dyes that bind to lipids and flow cytometry. We are also using genome sequencing and comparative genomics to try to correlate genetic differences with lipid production. Finally, we have established protocols for mating and sporulation that may eventually allow us to map genes required for lipid production using high-resolution QTL mapping approaches developed in our EBI program.

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