Simultaneous production of glycolic acid via the glyoxylate shunt and the synthetic (d)-xylulose-1 phosphate pathway increases product yield

Cost-practical of glycolic acid bioproduction by immobilized whole-cell catalysis accompanied with compressed oxygen supplied to enhance mass transfer

Bioprocess for Glycolic acid (GA) production from ethylene glycol by whole-cell catalysis of Gluconobacter oxydans is restrained by various biological impediments and high production costs. In this study, these limitations were subsided through the implementation of immobilized whole-cell bio-catalysis combined with increased oxygen supply. Results indicated that this strategy noticeably enhanced mass transfer efficiency, and prolonged cell life that significantly reduced the cost of biomass. Ultimately, with immobilized whole-cell catalysis in air-open and oxygen-open bioreactor, 41.3 and 66.9 g/L of GA was obtained within 48 h, with an increment of 62.0%. Additionally, in oxygen-compressed bioreactor, 63.3 g/L of GA was accumulated with the yield of 97.2%. Subsequently, 605.7 g of GA was produced after 10 rounds of recovery experiments. Although there was a slight decrease in GA production compared with pure-oxygen supply, production cost was reduced with limited oxygen supply. This strategy commendably demonstrated cost-practical bioprocess for GA production.

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-electrodialysis (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.

Integrated process for scalable bioproduction of glycolic acid from cell catalysis of ethylene glycol

Glycolic acid (GA) is presently booming as a versatile raw material in the fields of high-grade cosmetics, polymer degradable materials, and drug production. The biocatalysis of ethylene glycol (EG) to GA is promising, with environmentally friendly benefits, while the effective and straight bioproduction of GA qualified for polymer synthesis purity is a challenge. In this study, we combine whole cell catalysis step and acidification-purification step. A compressed oxygen supply in the sealed aerated stirred tank reaction (COS-SSTR) and a weak basic anion-exchange resins were integrated to develop an efficient process of GA bioproduction from EG. Finally, 110.5 g/L of GA was obtained at the yield of 94.4% and the volume productivity of 2.3 g/L/h in 48 h that presently is the greatest level for GA bioproduction. After 335 resins treatment of 5.0 L catalyzed broth containing 497.2 g EG, we obtained 575.4 g GA at the recovery rate of 98.9%.

Improving techno-economics of bioproduct glycolic acid by successive recycled-cell catalysis of ethylene glycol with Gluconobacter oxydans

Bioconversion of ethylene glycol (EG) to glycolic acid (GA) by the whole-cell of Gluconobacter oxydans in an aired stirred tank reactor (ASTR) with continuous substrate feeding yielded over 220 g/L of GA. However, the bioreactor productivity declined to an unfavorable level of 0.63 g/L/h due to negative feed-back by GA which inhibited the reaction. To overcome this problem, based on results obtained from techno-economic comparative analysis, we set up a successive recycled-cell catalytic bioprocessing ASTR, and carried out five consecutive cycles stably during 240 h. At the end of this process, total 490.7 g GA was accumulated with over 90% yield, and an average bioreactor productivity of 2.04 g/L/h. The twin strategies of end-product titer control and cell-recycling successfully demonstrated the large scale applicability of EG bioconversion to GA.