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A genetic engineering team of undergraduate students at The Chinese University of Hong Kong (CUHK) has been awarded a Gold medal at the International Genetically Engineered Machine (iGEM) 2019 Giant Jamboree held in Boston, USA. Under the project named “Banana Savior: The X Sense”, they have designed a rapid test for a new disease Banana Xanthomonas Wilt (BXW). They hope the novel design can help farmers in Africa and quarantine departments to realise early detection of the disease and help stop it from spreading. This is the sixth time that a CUHK team has won gold in the annual premier synthetic biology competition.

Banana is not only one of the most produced and consumed fruits, but also a major food source (plantain) in tropical areas, like some African countries. However, a new disease BXW, caused by Xanthomonas campestris pv. Musacearum (Xcm) bacteria, is threatening the survival of plantain trees. The incubation period for BXW is as long as several months. The bacteria may have already spread through air, water or animal contact before the symptoms appear. There is no cure and the infected tree will gradually die. In light of this, it is vital to identify the infected plant and implement control measures, including burning down the whole banana field. Therefore, the genetic engineering team at CUHK aims to design a simple and portable test kit for farmers and frontier quarantine departments to tackle the bacterial threat.

Transform E.coil into a “Receiver” of Bacterial Communication Signal

Xcm bacteria communicate with one another using chemical signal molecules, namely Diffusible Signal Factor (DSF). The E.coil bacteria, with its DNA manipulated by CUHK iGEM team, can create proteins for receiving DSF from Xcm bacteria. The team then engineered a circuit system inside E.coil bacteria. The presence of DSF will trigger the system and lead to the expression of a red chromoprotein, eforRed. It will eventually turn the test solution red as a signal of infection.

With reference to previous experiments of the same kind conducted by other universities, the team modified the E.coil system and has successfully prevented false positive from happening. The sensitivity of the system is also enhanced. That allows detection during the early phases of infection when the bacteria concentration is low. A test solution was created based on the team’s design and has proven theoretically effective and reliable in laboratory tests.

The 2019 CUHK iGEM team consists of 12 students majoring in interdisciplinary fields. They are from the School of Life Sciences, Department of Biomedical Engineering, and the School of Biomedical Sciences. In order to cater to the users need, the team has interviewed experts and stakeholders from various fields. They include banana experts in mainland China, medical and genetic professionals, as well as quarantine workers. The students were also required to draft online research reports and to arrange academic symposiums and exhibitions. The team presented their research works and results at the Giant Jamboree in Boston, and received recognition from the panel judges.

Professor Chan Ting Fung, one of the instructors of the team and associate professor of the School of Life Science at CUHK, remarked,“The students have done a great job in preparing for this project. In order to understand the real-world issue of banana diseases, they have traveled to Guangdong Academy of Agricultural Sciences (GDAAS) to talk to experts in banana breeding. Besides the innovation they have put into the project, I am also impressed by their persistence. They encountered a major setback and had to start almost from scratch half-way through their preparation, but they endured and worked very hard to achieve what they have set out to accomplish.”

About iGEM Competition 

iGEM is an annual premier synthetic biology competition worldwide for high school, undergraduate and postgraduate students.  It was established by the Massachusetts Institute of Technology (MIT) in 2004 to foster students’ learning in synthetic biology, promote collaboration among students and nurture biology talent.  Participating teams are required to specify, design, build and test simple biological systems made from standard, interchangeable biological parts. The accomplishments of these student teams often lead to important advances or provide solutions to tackle problems in medicine, food and nutrition, energy and the environment.