Optimization of lipid production by oleaginous yeast in continuous culture
Résumé
Oleaginous yeasts are microbial factories capable of conve rting carbohydrates and fat substrates into lipids. The transesterification of thes e lipids results in the production of biodiesel, a renewable energy source that has emerged as a pr omising and sustainable alternative to overcome the eminent depletion of fossil fuels and to redu ce the environmental impacts of petroleum exploitation. To bring biodiesel production a s a realistic technology to respond to the worldwide energy demand, process optimization is to b e pursued. In this paper, we performed a model-based optimization of lipid productivit y in continuous mode operation. It is considered that two input flow rates at different carbon/ nitrogen ratio are available as manipulated variables. The optimal control problem was sol ved numerically by using the control vector parameterization approach. A simple parameterizat ion with piecewise linear functions was found to be suitable for providing optimal performances . We showed that by driving the carbon/nitrogen ratio along the process adequately, optim al performances are attained. The control strategy here developed excels substantially an op eration with a single input flow rate with fixed C/N ratio. This work sets up useful guidelines towa rds optimal bioprocesses for microbial lipid production.