Engineering of Klebsiella oxytoca for production of 2,3‐butanediol using mixed sugars derived from lignocellulosic hydrolysates

Abstract

2,3‐Butanediol (2,3‐BDO) is a promising bulk chemical owing to its high potential in industrial applications. Here, we engineered Klebsiella oxytoca for the economic production of 2,3‐BDO using mixed sugars from renewable biomass. First, to improve xylose consumption, the xylose transporter gene (xylE) was integrated into the methylglyoxal synthase A (mgsA)‐coding gene loci, and the engineered CHA004 strain showed much faster consumption of xylose than wild‐type (WT) strain with 1.4‐fold increase of overall sugar consumption rate. To further improve sugar utilization, we performed adaptive laboratory evolution for 90 days. The evolved strain (CHA006) was evaluated by cultivating it in the media containing single‐ or mixed‐sugars, and it was clearly observed that CHA006 has improved sugar consumption and 2,3‐BDO production than those of the parental strain. Finally, we demonstrated the superiority of CHA006 by culturing in two lignocellulosic hydrolysates derived from sunflower or pine tree. Particularly, in the pine tree hydrolysate containing xylose, glucose, galactose, and mannose, the CHA006 strain showed much improved consumption rates for all sugars, and 2,3‐BDO productivity (0.73 g L−1 hr−1) increased by 3.2‐fold compared to WT strain. We believe that the engineered CHA006 strain can be a potential host in the development of economic bioprocess for 2,3‐BDO through efficient utilization of mixed sugars derived from lignocellulosic biomass.

Single Mathematical Parameter for Evaluation of the Microorganisms’ Growth as the Objective Function in the Optimization by the DOE Techniques

“…The population growth was improved by 12% in comparison to the result obtained at 37 °C . Thus, 37 °C has not been the optimal temperature for the cultivation of bacteria, even though it is commonly used in the research on K. pneumoniae and other representatives The calculated values of growth parameters (Figure 6) presented the region of optimal temperature around 33-34 • C. The population growth was improved by 12% in comparison to the result obtained at 37 • C. Thus, 37 • C has not been the optimal temperature for the cultivation of bacteria, even though it is commonly used in the research on K. pneumoniae and other representatives of this genus [2,25]. Therefore, the effective biomass production could be performed at lower temperatures that would reduce the energy (heat) consumption, thus the cost of the process [1].…”

“…The rising demand for biotechnological products as well as for the development of new bioprocesses requires continuous studies on microbial physiology and population growth [1,2]. In recent years, numerous studies on the optimization of cultivation conditions (e.g., medium composition, temperature, pH level) were conducted, which improved the mathematical description of bioprocesses [3][4][5][6][7].…”

Recent advances in the microbial production of C4 alcohols by metabolically engineered microorganisms

“…The final engineered strain could produce 2,3-BDO using mixed sugars obtained from lignocellulosic biomass. [30]…”

“…[15,[24][25][26][27][28] For example, C4 mono-alcohols such as 1-butanol, 2-butanol, and isobutanol are attractive biofuels that have been considered potential alternatives to gasoline, [15,24,25] while C4 di-and trialcohols such as 1,3-butanediol (1,3-BDO), 1,4-butanediol (1,4-BDO), 2,3-butanediol (2,3-BDO), and 1,2,4,-butanetriol (1,2,4-BTO) are bulk chemicals that can be used in the production of fuels, plastics, cosmetics, and pharmaceuticals. [27] For these reasons, a significant volume of research has focused on improving and developing the capabilities of microbial cell factories that can effectively produce these C4 alcohols, [29][30][31][32][33][34][35] with the most efficient metabolic engineering strategies depending on the characteristics of the target product, particularly whether it is found in nature or not.…”

Engineering of Klebsiella oxytoca for the Production of 2,3-Butanediol from High Concentration of Xylose

“…However, wild-type K. oxytoca showed poor utilization ability of xylose compared to other sugars (glucose and galactose). − Therefore, various strategies such as metabolic and evolutionary engineering have been implemented to enable rapid xylose assimilation, which can increase the productivity as well as yield of 2,3-BDO. , …”