Kinetic analysis on the production of polyhydroxyalkanoates from volatile fatty acids by Cupriavidus necator with a consideration of substrate inhibition, cell growth, maintenance, and product formation

Volatile fatty acids (VFAs) could be utilized by Cupriavidus necator (previously named as Ralstonia eutropha) as its sole carbon and energy source for growth and polyhydroxyalkanoates (PHAs) synthesis. In such a biosynthesis, VFAs at a high concentration had an inhibition on cell growth and deteriorate metabolite production. In this work the kinetics of PHAs production and consumption of VFAs by C. necator with simultaneous considerations of substrate inhibition, cell growth, maintenance and product formation were explored. The growth of C. necator and production of PHAs were significantly affected by the initial VFAs concentration. The cell growth was inhibited under initial substrate-sufficient conditions, and the cell activities could be resumed with the consumption of VFAs in batch cultures. Experimental results verify that the model established in this work was able to appropriately describe the PHA production from VFAs by C. necator.