Jämsä Tytti, Claassens Nico J, Salusjärvi Laura, Nyyssölä Antti
VTT Technical Research Centre of Finland Ltd., Tekniikantie 21, 02150, Espoo, Finland.
Laboratory of Microbiology, Wageningen University, Stippeneng 4, 6708WE, Wageningen, The Netherlands.
Microb Cell Fact. 2024 Dec 23;23(1):345. doi: 10.1186/s12934-024-02615-7.
Biocatalysis offers a potentially greener alternative to chemical processes. For biocatalytic systems requiring cofactor recycling, hydrogen emerges as an attractive reducing agent. Hydrogen is attractive because all the electrons can be fully transferred to the product, and it can be efficiently produced from water using renewable electricity. In this article, resting cells of Cupriavidus necator H16 harboring a NAD-dependent hydrogenase were employed for cofactor recycling to reduce D-xylose to xylitol, a commonly used sweetener. To enable this bioconversion, D-xylose reductase from Scheffersomyces stipitis was heterologously expressed in C. necator.
D-xylose reductase was successfully expressed in C. necator, enabling almost complete bioconversion of 30 g/L of D-xylose into xylitol. It was found that over 90% of the energy and protons derived from hydrogen were spent for the bioconversion, demonstrating the efficiency of the system. The highest xylitol productivity reached was 0.7 g/L/h. Additionally, the same chassis efficiently produced L-arabitol and D-ribitol from L-arabinose and D-ribose, respectively.
This study highlights the efficient utilization of renewable hydrogen as a reducing agent to power cofactor recycling. Hydrogen-oxidizing bacteria, such as C. necator, can be promising hosts for performing hydrogen-driven biocatalysis.
生物催化为化学过程提供了一种潜在的更绿色的替代方法。对于需要辅因子循环利用的生物催化系统，氢气成为一种有吸引力的还原剂。氢气具有吸引力是因为所有电子都能完全转移到产物中，并且利用可再生电力可以从水中高效生产氢气。在本文中，使用携带NAD依赖性氢化酶的食酸丛毛单胞菌H16静息细胞进行辅因子循环利用，将D-木糖还原为木糖醇（一种常用甜味剂）。为实现这种生物转化，树干毕赤酵母的D-木糖还原酶在食酸丛毛单胞菌中进行了异源表达。
D-木糖还原酶在食酸丛毛单胞菌中成功表达，能够将30 g/L的D-木糖几乎完全生物转化为木糖醇。研究发现，来自氢气的能量和质子超过90%用于生物转化，证明了该系统的效率。木糖醇的最高生产率达到0.7 g/L/h。此外，同一底盘分别从L-阿拉伯糖和D-核糖高效生产L-阿拉伯糖醇和D-核糖醇。
本研究强调了可再生氢气作为还原剂为辅因子循环提供动力的高效利用。诸如食酸丛毛单胞菌之类的氢氧化细菌有望成为进行氢驱动生物催化的宿主。
