Evaluating the efficacy of genetically engineered Escherichia coli W (ATCC 9637) to produce limonene from industrial sugar beets (Beta vulgaris L.)

There is an increasing need for renewable fuels and chemicals from sustainable feedstocks to decrease the negative global impacts caused by the rampant use of fossil fuels. Juice from industrial sugar beets is a sucrose-rich substrate with potential as a biofuel and chemical feedstock. In this study, juice from sugar beets was utilized as a novel feedstock to produce the cyclic hydrocarbon limonene by genetically engineered E. coli W (ATCC 9637). To optimize this process, limonene production, E. coli viability, pH, and residual sucrose in the media were evaluated in aerobic trials in bioreactors using various concentrations of beet juice diluted in lysogeny broth. Limonene production in these trials ranged from 0.95-3.13 mg/L/d, however sucrose from beet juice was not catabolized. Cultivation media supplemented with beet juice can be utilized to produce limonene, however further optimization is needed for the E. coli strains to effectively metabolize sucrose from beet juice.