Biotransformation of glycerol to 3-hydroxypropionaldehyde: Improved production by in situ complexation with bisulfite in a fed-batch mode and separation on anion exchanger.

3-Hydroxypropionaldehyde (3HPA) is an important C3 chemical that can be produced from renewable glycerol by resting whole cells of Lactobacillus reuteri. However the process efficiency is limited due to substrate inhibition, product-mediated loss of enzyme activity and cell viability, and also formation of by-products. Complex formation of 3HPA with sodium bisulfite and subsequent binding to Amberlite IRA-400 was investigated as a means of in situ product recovery and for overcoming inhibition. The adsorption capacity and -isotherm of the resin were evaluated using the Langmuir model. The resin exhibited maximum capacity of 2.92mmol complex/g when equilibrated with 45mL solution containing an equilibrium mixture of 2.74mmol 3HPA-bisulfite complex and 2.01mmol free 3HPA. The dynamic binding capacity based on the breakthrough curve of 3HPA and its complex on passing a solution with 2.49mmol complex and 1.65mmol free 3HPA was 2.01mmol/g resin. The bound 3HPA was desorbed from the resin using 0.20M NaCl with a high purity as a mixture of complexed- and free 3HPA at a ratio of 0.77mol/mol. Fed-batch biotransformation of glycerol (818.85mmol) with in situ 3HPA complexation and separation on the bisulfite-functionalized resin resulted in an improved process with consumption of 481.36mmol glycerol yielding 325.54mmol 3HPA at a rate of 17.13mmol/h and a yield of 68 mol%. Also, the cell activity was maintained for at least 28h.