The team's goal is to transform large quantities of coffee waste into affordable myopia-preventive medications using synthetic biology techniques. However, an investigation of coffee grounds from various coffee shop brands reveals significant differences in particle size, moisture content, and color. These differences affect the caffeine extraction efficiency, leading to reduced utilization of coffee grounds and unstable 7-MX yields. To maximize coffee grounds utilization and stabilize 7-MX production, it is essential to explore methods for processing different types of coffee waste or standardize processing techniques to achieve consistent caffeine extraction. Standardizing the handling of coffee waste will better benefit human eyesight.
According to the International Coffee Organization, approximately 6 million tons of coffee grounds are generated globally each year. However, current disposal methods primarily involve incineration and landfill, which cause significant environmental harm. There are some technologies aimed at processing coffee grounds, such as extracting their key components. Additionally, coffee grounds have been applied in fields like agriculture and fermentation [3], but these efforts are insufficient to fully address the issue of coffee grounds accumulation and waste.In response, the project developed a biosynthetic system that directly converts caffeine from coffee grounds into the high-value compound 7-MX. This offers a new approach to the industrial-scale production of 7-MX and provides an innovative solution to the problem of coffee grounds waste and accumulation.
Current Methods for Coffee Grounds Disposal
According to existing reports, 7-MX is effective in alleviating myopia and is considered a promising potential treatment for this condition [1]. However, the high production costs have impeded the large-scale production and clinical application of 7-MX [2]. Discussions with myopia treatment experts have revealed that many companies have not commercialized 7-MX due to its prohibitive production costs. In response, the project has developed a simple and efficient biosynthesis system that converts caffeine from coffee grounds directly into 7-MX, significantly reducing production costs. Experimental data supports the feasibility of this method for large-scale 7-MX production, potentially lowering costs and facilitating further commercialization to address myopia issues.
7-MX's mechanism of alleviating myopia
The project utilizes the Ndm enzyme system from Pseudomonas putida CBB5. As observed in the metabolic pathway, other enzymes within this system can selectively demethylate different positions on caffeine, enabling the synthesis of other methylxanthine compounds, such as 1-MX, 3-MX, and paraxanthine (PX). These compounds also hold significant application value. For example, 1-MX can enhance the radiosensitivity of tumor cells, 3-MX serves as an adenosine antagonist [4], and PX can stimulate thermogenesis and increase plasma adrenaline levels.
Metabolic Pathway of Pseudomonas putida CBB5
Coffee grounds contain large amounts of cellulose, hemicellulose, lignin, lipids, and proteins, making them suitable for direct use as animal feed, plant fertilizer, and biofuel. Additionally, coffee grounds are rigid, biodegradable, and porous particles, making them an ideal functional filler for polymer composites, which can enhance the mechanical properties of polymer matrices while reducing production costs.
Before formally commencing laboratory experiments, all members of the project underwent a two-month theoretical training. They also participated in intensive training on experimental skills and associated safety precautions.
Activated carbon is widely used in environmental pollution control due to its excellent adsorption properties. However, the large-scale production of activated carbon is constrained by the quality, cost, and availability of raw materials. Previous studies have demonstrated that waste biomass, such as inexpensive plant straw, coconut shells, cocoa shells, walnut shells, bagasse, wood chips, and black liquor from pulp production, can be activated to produce high-performance activated carbon. Among various biomass sources, coffee grounds, with an annual global output of approximately 6 million tons, are readily available as raw material.
[1] Trier, K., Cui, D., Ribel-Madsen, S., & Guggenheim, J. (2023). Oral administration of caffeine metabolite 7-methylxanthine is associated with slowed myopia progression in Danish children. The British journal of ophthalmology, 107(10), 1538–1544. https://doi.org/10.1136/bjo-2021-320920
[2] Retnadhas, Sreeahila, Gummadi, Sathyanarayana, & N. (2018). Identification and characterization of oxidoreductase component (ndmd) of methylxanthine oxygenase system in pseudomonas sp ncim 5235. APPLIED MICROBIOLOGY AND BIOTECHNOLOGY, 102(18), 7913-7926.
[3]Design iGEM NEFU_China 2023
[4] Khalid, H. R. , Algharrawi, Ryan, M. , Summers, Sridhar, & Gopishetty, et al. (2015). Direct conversion of theophylline to 3-methylxanthine by metabolically engineered e. coli. Microbial cell factories.
[5] 任杰. 咖啡渣活性炭的制备、表征及吸附性能研究. (Doctoral dissertation, 广东工业大学).
[6]Kang, L., Zeng, Y., Wang, Y., Li, J., Wang, F., Wang, Y., Yu, Q., Wang, X., Ji, R., Gao, D., & Fang, Z. (2022). Removal of pollutants from wastewater using coffee waste as adsorbent: A review. Journal of Water Process Engineering.
[7] 罗鑫杰, 王宝玲, 李雪梅, 张鸿飞, 陶娆, & 李俊等. (2024). 咖啡渣在高分子复合材料中的应用研究综述. 云南化工, 51(2), 19-21.