Potassium (K), Phosphorus (P) and Nitrogen (N) are three macronutrients for plants, and deficiencies in any of these can lead to plant diseases. By creating a biological sensor that can quickly provide soil status to plant owners, we can prevent plant diseases due to the lack of nutrients.

In previous iGEM competitions, multiple teams have worked on nitrate and phosphate responsive promoters, but none of them attempted to provide a potassium responsive promoter. In view of this, our team is constructing a biological sensor in E. coli, which can detect NPK levels in the surrounding environment and give responses in the form of colors. In addition, we are characterizing the effects of a dual output system, in contrast to a single output system, in order to anticipate the expression of multiple outputs in a single system.

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The Journey of HKUST-Rice iGEM team

We are HKUST-Rice iGEM team. Our team is the first cross continental team in iGEM, comprising of 32 student members- 18 from the Hong Kong University of Science and Technology and 14 from Rice University. The benefit from forming a large joint team, we have members coming from different disciplinary which allow us to think from different perspectives. With the combined force form our members, we show the result of our work over the summer.

Taking the native metabolic pathway found in E. coli, we have designed a potassium ions (K⁺) regulated construct and a nitrate (NO3^-) regulated construct that could potentially report the K⁺ and NO3^- level in soil. Knowing that previous iGEM team also worked on nitrate regulated promoter and phosphate regulated promoter, our team utilize those promoter and further characterize in order to give more information about those promoters.

In addition, we are characterizing the effects of a dual output system, in contrast to a single output system, in order to predict the expression of multiple outputs in a single system.

When it comes to the real application method of our biosensors, our team considered 2 factors, Biological safety and feasibility. Biological safety are our priority, especially when our focus are related to the agricultural business. In our plan of applying the biosensor, we choose to deliver the biosensor in a cell-free system, which have no capability to sustain itself in the wild. However when we factor in the feasibility, we think that delivering our biosensor in common soil bacteria will be more practical. Hence we perform proof of concept experiments to demonstrate our concepts.

Besides staying in the lab, we also take every opportunity to engage the community to achieve 2 aims, to introduce synthetic biology to the younger community through debating and to interact with the community and gather their perceptions regarding biosensor and genetic engineering technology. Through engaging the community, we also gain valuable feedbacks and comments which we then use to improve our design.