Optimal exponential feeding strategy for dual-substrate biostimulation of phenol degradation using Cupriavidus taiwanensis

The exponential feeding strategy (EFS) of dual substrates (i.e., phenol and glycerol) was applied to optimize the overall performance of phenol degradation by Cupriavidus taiwanensis R186. Addition of a second substrate (e.g., glycerol) could stimulate the phenol biodegradation efficiency of strain R186. Hence, a feasible EFS was developed for fed-batch phenol biodegradation using the dual-substrate biostimulation technique. The phenol degradation kinetics was well characterized with proposed model and response surface analysis. Our findings quantitatively revealed that glycerol could effectively enhance the phenol degradation performance, as the highest phenol degradation efficiency occurred with the supplementation of 0.8-1.2 g L^-1 of glycerol. The optimal dual-substrate EFS was identified via contour analysis and kinetic modeling. With the optimal dual-substrate EFS (i.e., a feeding rate constant (α₁ and α₂) of 0.5 and 0.3, respectively), the shortest time (ca. 13.80 h) for phenol degradation was achieved with a specific growth rate of ca. 0.281 h^-1.