D-甘露醇是一种六碳糖醇,是自然界中最丰富的多元醇之一。具有抗氧化和渗透压调节作用,并且不受人体代谢的影响,D-甘露醇已广泛应用于功能食品和制药行业。目前,D-甘露醇工业生产的主要途径是化学加氢。此外,D-甘露醇可通过微生物代谢或催化产生。与化学加氢相比,微生物法合成甘露醇不产生副产物山梨醇,反应条件温和,特异性强,高转化率。微生物发酵因易于获得菌株和原料以及简单的产品分离而受到赞誉。微生物催化通常采用多酶偶联策略,它使用工程细菌产生的酶进行全细胞催化,并引入辅因子再循环途径来补充昂贵的辅因子。该方法可以在温和的条件下用廉价的底物实现高产率而不形成副产物。然而,微生物方法在D-甘露醇工业生产中的应用受到发酵培养基和底物成本高、反应时间长的限制。本文综述了已报道的微生物生产D-甘露醇的方法。包括使用高产菌株及其发酵过程,低成本基板的利用,全细胞催化策略,和高生产率的过程控制。甘露醇的生物合成不仅对促进产业升级、实现绿色制造具有重要意义,同时也为新的生物基产品的开发提供了有力的支持,以满足日益增长的市场需求。随着技术创新和产业链的不断完善,有望成为未来甘露醇生产的主要方式之一。
D-mannitol is a six-carbon sugar alcohol and one of the most abundant polyols in the nature. With antioxidant and osmotic pressure-regulating effects and non-metabolism by the human body, D-mannitol has been widely used in functional food and pharmaceutical industries. At present, a major way for industrial production of D-mannitol is chemical hydrogenation. In addition, D-Mannitol can be produced by microbial metabolism or catalysis. Compared with the chemical hydrogenation, the microbial methods for synthesizing mannitol do not produce sorbitol as a by-product and have the advantages of mild reaction conditions, strong specificity, and high conversion rate. Microbial fermentation is praised for easy access of strains and raw materials and simple separation of the product. Microbial catalysis usually adopts a multi-enzyme coupling strategy, which uses enzymes produced by engineered bacteria for whole-cell catalysis, and the cofactor recycling pathway is introduced to replenish expensive cofactor. This method can achieve high yields with cheap substrates under mild conditions without the formation of by-products. However, the application of microbial methods in the industrial production of D-mannitol is limited by the high costs of fermentation media and substrates and the long reaction time. This article reviews the reported microbial methods for producing D-mannitol, including the use of high-yielding strains and their fermentation processes, the utilization of low-cost substrates, whole-cell catalytic strategies, and the process control for high productivity. The biosynthesis of mannitol is not only of great significance for promoting industrial upgrading and realizing green manufacturing, but also provides strong support for the development of new bio-based products to meet the growing market demand. With the continuous improvement of technological innovation and industrial chain, it is expected to become one of the main ways of mannitol production in the future.