One-step continuous/semi-continuous whole-cell catalysis production of glycolic acid by a combining bioprocess with in-situ cell recycling and electrodialysis

Bioprocess for successive bio-production of glycolic acid (GA) from ethylene glycol (EG) using Gluconobacter oxydans is hindered by strong end-product inhibitory effect. Based on the model of compressed oxygen supplied-sealed stirred tank reactor (COS-SSTR), we developed a new system by attaching an ultrafiltration instrument and electrodialysis cell to in-situ separate GA, including conductivity meter to control automatic EG feeding. The combined bioprocess was therefore set up as compressed oxygen supplied cell catalysis-ultrafiltration-electro-dialysis (COS-CUE). In comparison with the conventional resin and electrodialysis separation process, this device simplified the whole bioprocess. We realized the potential of combined bioprocess for producing GA without EG through continuous/semi-continuous 'one-step' process. Finally, 288.4 g GA was obtained at the yield of 96.5% and average productivity of 4.0 g/L/h in 72 h, with an increment of 148.8% and 20.9% in production compared with batch and cell-recycling fermentation.