As a leading global platform for synthetic biology competitions, iGEM has significantly contributed to the rapid development of this field. The platform fosters international knowledge exchange and technological collaboration through promoting teams to learn from and build upon the innovative experiences of the world's top research groups. To better integrate into this community, we have shared our valuable experiences from the competition on the iGEM platform, including contributions in areas such as experimental design and project implementation. We hope these insights will inspire and assist future researchers in advancing the future of synthetic biology.
At the outset of our project, our team conducted an in-depth investigation into the disposal and reuse of coffee grounds, a common form of food waste, which led us to choose the food category. Coffee, one of the top three beverages globally, generates a significant amount of waste annually. Data indicates that processing one ton of coffee beans produces approximately 650 kilograms of coffee grounds, and the production of 1 kilogram of instant coffee generates 2 kilograms of wet coffee grounds. With the rapid expansion of the global coffee market, the annual production of coffee grounds has now exceeded 6 million tons.
If we were to imagine 6 million tons of coffee grounds as cubic meters, these cubes could form a single large cube with a side length of approximate 783 meters, which is equivalent to about 1.05 standard tennis courts in area. Improper disposal of such a volume would pose substantial environmental challenges.
Currently, the most common methods for utilizing coffee grounds are low-efficient approaches such as composting and deodorizing. Thus, finding more efficient ways to reuse coffee grounds is both urgent and necessary. Our approach leverages bioengineering and metabolic engineering techniques to repurpose coffee grounds for the production of high-value, high-efficiency products such as 7-methylxanthine (7-MX).
This project also provides future iGEM teams with a biological framework for addressing the issues of food waste, and promotes efficient resource recovery. We hope this work will deepen the understanding of current issues related to coffee grounds and inspire additional innovative strategies for their reuse, ultimately making a significant social impact.
The natural caffeine demethylation pathway found in Pseudomonas putida CBB5 offers a promising starting point for the synthesis of 7-MX, a compound with potential therapeutic applications for myopia treatment. The production of 7-MX holds significant importance in synthetic biology. This year, our team utilized Escherichia coli BW25113 as a chassis strain and, through a series of innovative bioengineering techniques, successfully converted caffeine into 7-MX.
Significant progress was made in modifying the NdmB enzyme. By employing directed evolution and rational design, we not only improved the efficiency of 7-MX production but also engineered a single mutant enzyme, NdmBs, which is capable of performing the dual functions of NdmB and NdmA. This innovative enzyme modification strategy enhances production efficiency and simplifies the process, paving the way for industrial-scale production and commercialization of 7-MX.
Our team successfully developed a whole-cell biosensor for 7-MX through real-time monitoring the production process and further optimizing production conditions. These technological advances provide robust tools for synthesizing 7-MX and offer valuable insights for the synthetic biology field.
By introducing different plasmids, our biosensor allows the conversion of methylxanthines to xanthine, which facilitatesthe detection of these compounds. For example, by introducing the pYB1s-ndmDCAE plasmid into the chassis strain, we achieved the production and detection of hypoxanthine derivatives, which are currently valued at 440 US dollars per gram.
These outcomes offer a valuable modular reference for future iGEM teams and open up new possibilities for the development and application of synthetic biology. Through these innovative experimental designs and engineering techniques, we hope to inspire more teams to drive progress in synthetic biology, contributing to human health and sustainable development.
Throughout the iGEM competition, our team actively promoted the fundamental knowledge and related theories of synthetic biology through a public WeChat platform. The content was designed to be accessible to both professionals and the general public, including detailed introductions to experimental skills and fundamental principles, as well as engaging comics that covered biosafety knowledge. The platform featured a combination of in-depth, logically structured articles and more accessible, entertaining content to cater to a diverse audience.
