Optimization of lipid production by oleaginous yeast in continuous culture

摘要

Oleaginous yeasts are microbial factories capable of converting carbohydrates and fat substrates into lipids. The transesterification of these lipids results in the production of biodiesel, a renewable energy source that has emerged as a promising and sustainable alternative to overcome the eminent depletion of fossil fuels and to reduce the environmental impacts of petroleum exploitation. To bring biodiesel production as a realistic technology to respond to the worldwide energy demand, process optimization is to be pursued. In this paper, we performed a model-based optimization of lipid productivity 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 solved numerically by using the control vector parameterization approach. A simple parameterization 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, optimal performances are attained. The control strategy here developed excels substantially an operation with a single input flow rate with fixed C/N ratio. This work sets up useful guidelines towards optimal bioprocesses for microbial lipid production.