Yeast for Ethanol and Carotenoid Productions
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Lignocellulosic biomass is an attractive source of renewable energy. Saccharomyces cerevisiae is often a biocatalyst of choice because of its ability to produce ethanol, as well as its robustness to harsh processing conditions. However, by-products from pretreatment and hydrolysis of biomass can have significant inhibitory effects on the growth of S. cerevisiae and biofuel production. We utilize the visualization of evolution in real time (VERT) and genome shuffling to generate strains of S. cerevisiae with increased growth rates of up to 13% and 100% in the presence of the by-products furfural and 5-(hydroxymethyl) furfural, respectively. In addition to biofuel production, S. cerevisiae is also a major biocatalyst used for production of biochemicals. The various products that it has been engineered to produce includes carotenoids, which has potential nutraceutical benefits. We have previously developed an evolutionary engineering strategy that couples cell survival with increased carotenoids production and successfully developed carotenoids hyper-producing strains. Intercellular accumulation of the product has been observed in these strains, potentially limiting its production. We attempt to use rational engineering to further improve the productivity of the hyper-producing strains by screening for carotenoids exporters that will potentially increase the driving force for carotenoids production and facilitate the development of a two-phase simultaneous fermentation and extraction system. A variety of genes encoding plasma membrane ATP-binding cassette transporters were cloned into overexpression vectors and transformed into carotenoid- producing yeast. Increased production of the carotenoid β-carotene was observed in a strain containing an overexpression vector for SNQ2.
Cheng, Clint (2015). Yeast for Ethanol and Carotenoid Productions. Master's thesis, Texas A & M University. Available electronically from