Oligosaccharides production from coprophilous fungi: An emerging functional food with potential health-promoting properties

Functional foods are essential food products that possess health-promoting properties for the treatment of in?fectious diseases. In addition, they provide energy and nutrients, which are required for growth and survival.  They occur as prebiotics or dietary supplements, including oligosaccharides, processed foods, and herbal  products. However, oligosaccharides are more efficiently recognized and utilized, as they play a fundamental  role as functional ingredients with great potential to improve health in comparison to other dietary supplements.  They are low molecular weight carbohydrates with a low degree of polymerization. They occur as fructooligo?saccharide (FOS), inulooligosaccharadie (IOS), and xylooligosaccahride (XOS), depending on their mono?saccharide units. Oligosaccharides are produced by acid or chemical hydrolysis. However, this technique is liable  to several drawbacks, including inulin precipitation, high processing temperature, low yields, and high pro?duction costs. As a consequence, the application of microbial enzymes for oligosaccharide production is recog?nized as a promising strategy. Microbial enzymatic production of FOS and IOS occurs by submerged or solid-state  fermentation in the presence of suitable substrates (sucrose, inulin) and catalyzed by fructosyltransferases and  inulinases. Incorporation of FOS and IOS enriches the rheological and physiological characteristics of foods. They  are used as low cariogenic sugar substitutes, suitable for diabetics, and as prebiotics, probiotics and nutraceutical  compounds. In addition, these oligosaccharides are employed as anticancer, antioxidant agents and aid in  mineral absorption, lipid metabolism, immune regulation etc. This review, therefore, focuses on the occurrence,  physico-chemical characteristics, and microbial enzymatic synthesis of FOS and IOS from coprophilous fungi. In  addition, the potential health benefits of these oligosaccharides were discussed in detail.

功能性食品是一类兼具健康促进功效、可辅助治疗感染性疾病的必需食品。此外，此类食品可为机体提供生长与存活所需的能量与营养物质。它们以益生元或膳食补充剂的形式存在，涵盖低聚糖、加工食品及草本制品。相较其他膳食补充剂，低聚糖的识别与利用效率更高，作为功能性成分可发挥核心作用，具备改善健康的巨大潜力。低聚糖属于聚合度较低的低分子量碳水化合物，根据单糖组成的不同，可分为低聚果糖（fructooligosaccharide, FOS）、低聚菊糖（inulooligosaccharide, IOS）以及低聚木糖（xylooligosaccharide, XOS）。传统上低聚糖可通过酸解法或化学水解法制备，但该工艺存在诸多缺陷，如菊糖沉淀、加工温度过高、产物得率低以及生产成本高昂等。因此，利用微生物酶制剂制备低聚糖被认为是极具前景的替代方案。低聚果糖与低聚菊糖的微生物酶法制备，可通过以适宜底物（蔗糖、菊糖）为碳源的液体深层发酵或固态发酵实现，反应由果糖基转移酶与菊糖酶催化完成。将低聚果糖与低聚菊糖添加至食品中，可改善食品的流变学特性与生理功能。此类低聚糖可作为低致龋性糖替代品，适用于糖尿病患者，同时可用作益生元、益生菌及营养保健化合物。此外，这类低聚糖还可作为抗癌、抗氧化剂，有助于促进矿物质吸收、调节脂质代谢与免疫功能等。因此，本综述重点探讨了从粪生真菌中提取的低聚果糖与低聚菊糖的存在形式、理化特性及微生物酶法合成工艺，同时详细阐述了这类低聚糖的潜在健康益处。