(481b) Reactor Design and Optimization of ?-Amino Ester Hydrolase for Synthesis of Cephalexin

Improvement of pharmaceutical production quality has recently been a focus through incorporation of end-to-end continuous processing [1]. Enzymatic ß-lactam antibiotic synthesis has been one focus for continuous manufacturing, and α-amino ester hydrolases (AEHs) are currently being explored for use in cephalexin synthesis due to their high reactivity and selectivity. In this work, several reactors were simulated to determine how reactor type and configuration impacts conversion, fractional yield toward cephalexin, and volumetric productivity for AEH-catalyzed synthesis of cephalexin. Reactor configurations studied include a single continuous stirred-tank reactor (CSTR) and single plug flow reactor (PFR) as well as two CSTRS and CSTR + PFR in series. Substrate concentrations fed to the reactors as well as enzyme concentration in the reactor were varied.

The presence of substrate inhibition was found to have a negative impact on all reactor configurations studied. No reactor configuration simultaneously allowed high substrate conversion, high fractional yield, and high productivity; however, a single PFR was found to enable the highest substrate conversion with higher fractional yields than all other reactor configurations by minimizing substrate inhibition. Finally, to further demonstrate the impact of substrate inhibition, a simulated AEH engineered to improve substrate inhibition was studied in a single CSTR and Pareto optimal fronts were compared to Pareto fronts for the improved AEH. Overall, reduced substrate inhibition realized through protein engineering would allow for high substrate conversion, fractional yield, and productivity with only a single CSTR [2].

1. Lee, S.L., et al., Modernizing Pharmaceutical Manufacturing: from Batch to Continuous Production. Journal of Pharmaceutical Innovation, 2015. 10(3): p. 191-199.
2. Lagerman, C.E., et al., Reactor Design and Optimization of α-Amino Ester Hydrolase- Catalyzed Synthesis of Cephalexin. Frontiers in Bioengineering and Biotechnology, 2022. 10.