| dc.description.abstract | Biocatalysts have been increasingly targeted to produce bio-fuels, pharmaceuticals and synthetic and natural chemicals due to a rising interest in sustainability and safety. The use of biocatalysts can eliminate the need for brute chemical synthesis and the toxic materials utilized in the process. Beta-carotene is a favorable candidate for microbial production as it is naturally produced in several different organisms and the pathway of production is well characterized. A brightly colored pigment which is used in a wide array of industries such as nutraceuticals, food and cosmetics, beta-carotene has a predicted market value of 247 million dollars by 2019. This work focuses on applying upstream and midstream approaches to maximize titer, yield and productivity of beta-carotene production under fed-batch operation using a carotenoid hyper-producer (SM14), an engineered strain of Saccharomyces cerevisiae. Bench-top bioreactor experiments determined ethanol feeding, when compared to glucose feeding, results in a 64% improvement in productivity. Glucose and ethanol feeding increased the maximum titer to 179 mg/L which is a 44% improvement when compared to batch experiments. In addition, yield was increased to 21 mg/g DCW, a 22% improvement compared to batch results. Response Surface Methodology (RSM) was utilized to optimize minimal YNB media for maximum biomass and titer production. Sixteen different compositions were studied and the analysis showed that optimal composition results in an improvement of 243.35% in biomass production, 198.21% in titer and 106.49% in productivity. | en |
