Efficient production of lactobionic acid using genetically engineered Pseudomonas taetrolens as a whole-cell biocatalyst

• Published in: Enzyme and microbial technology 2020-11, Vol.141, p.109668-109668, Article 109668
• Main Authors: Oh, Yu-Ri, Jang, Young-Ah, Hong, Soon Ho, Han, Jeong Jun, Eom, Gyeong Tae
• Format: Article
• Language: English
• Subjects: Homologous expression; Lactobionic acid; Pseudomonas taetrolens; Quinoprotein glucose dehydrogenase; Whole cell biocatalysis
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/j.enzmictec.2020.109668

•Quinoprotein glucose dehydrogenase gene was expressed in Pseudomonas taetrolens.•Lactose-oxidizing activity and LBA production titer of P. taetrolens was improved.•The recombinant P. taetrolens was used as a WCB for LBA production.•LBA productivity of the WCB was highly increased to 16.7 g/L/h.•The WCB was used for 7 rounds without a significant decrease in LBA productivity. Lactobionic acid (LBA) has been widely used in the food, pharmaceutical, and cosmetic industries. Pseudomonas taetrolens is an efficient LBA-producing bacterium. To improve the LBA-production ability of P. taetrolens, we modified the strain by genetic engineering. We performed homologous expression of the quinoprotein glucose dehydrogenase gene in P. taetrolens and measured the intracellular lactose-oxidizing activity and LBA production titer. In flask cultures at 12 h of incubation, the intracellular lactose oxidizing activity (0.159 U/g dry weight cell) and LBA production titer (77.2 g/L) of the recombinant P. taetrolens were approximately 118 % and 69 % higher than those (0.073 U/g dry weight cell and 45.8 g/L, respectively) of wild-type P. taetrolens. Using this recombinant strain as a whole-cell biocatalyst (WCB), the effects of reaction parameters, such as reaction temperature, cell density, and cell harvest time, were investigated on LBA production. Under optimized reaction conditions, the LBA production titer, yield, and productivity of WCB were 200 g/L, 95.6 %, and 16.7 g/L/h, respectively. Compared with our previous study, LBA production titer, yield, and productivity, which are key factors for industrial LBA production, were significantly improved by fermentation of wild-type P. taetrolens. Moreover, the reaction for LBA production could be performed up to seven times without a significant reduction in productivity, implying that this WCB was rather robust. Our results suggest that the utilization of whole-cell biocatalysis using recombinant P. taetrolens provides a potential solution to achieve economically feasible production of LBA.