L-Ergothioneine (EGT, ERGO) is a natural chiral amino-acid antioxidant biosynthesized in certain bacteria and fungi. It is an important bioactive compound which has been used as a radical scavenger, an ultraviolet ray filter, a regulator of oxidation-reduction reactions and cellular bioenergetics, and a physiological cytoprotector, etc. EGT is a new fermentation product with high additional value due to its physiological and pharmacological properties, good security and stability. It has broad applications in cosmetics, functional foods, pharmaceuticals, therapeutics, biomedicine, and so on. OXIS International, Inc. manufactures EGT through chemical synthesis. However, we expect EGT production by submerged fermentation of mushrooms would show great advantages over chemical synthesis, natural bio-extraction and solid fermentation.
The Bioprocess Engineering research group led by JIANG Wenxia at Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, obtained a high EGT-producing edible fungal strain of Pleurotus ostreatus through screening. We established methods for rapid quantitative measurement of EGT in fermentation broth and products by HPLC. By setting up a control strategy of high density fermentation, we achieved over 160 mg/L production of EGT in the fermentation broth of a 200 L fermentor. We further developed water-extracting techniques to replace organic solvent-extracting methods and explored isolation and purification techniques for industrialization that could ensure the security of operational process and product concurrently. Varying amounts of EGT products from 0.8% to 99% were prepared by simplified technology in extraction and purification, so as to satisfy different requirements in application. The yields of extraction were in the range of 75% to over 90%. 7 patents for invention dealing with strain, fermentation, extraction, purification, detection and oral preparations have been applied in China.
The scientific achievements filled the gap of EGT research in mainland of China, opened up the whole processing route, accomplished the highest yields and the largest-scale in fermentation around the world. Natural edible fungi and edible materials were used in EGT fermentation, to achieve the lowest extraction cost and high safety of manufacturing processes for extracting EGT by water. The extraction and purification techniques were easy to be implemented with high extraction yield. Moreover, the product security was assured so that the products can be used directly for food without purification, without transgenic risks or certain of custom taboos. The discharge of waste water and waste residues were minimized in the manufacturing process. The technique laid the foundation for building up a production line of EGT biosynthesis worldwide.
This research was supported by grants from the Key Projects in the Tianjin Science & Technology Pillar Program (10ZCKFSY06300) and Tianjin Municipal Natural Science Foundation for Youths (13JCQNJC10100).
