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Welcome to the Engineering Page! Here, we take you on a captivating journey through the dynamic world of engineering, highlighting the intricate flow of ideas, the continuous iterations, both successes and failures, and the resilience it takes to develop groundbreaking solutions. Our projects were anything but straightforward, necessitating in-depth research, creative modeling, and persistent adjustments. We emphasize the pivotal role of iteration in engineering, where continuous refinement and learning from mistakes lead to progress. Alongside our achievements, we acknowledge and embrace failures as integral steps towards innovation. As you explore our engineering adventures, you'll witness the challenges we tackled, the cutting-edge research we harnessed, and the tools and technologies that fueled our endeavors. Join us in celebrating the engineering spirit that drives us forward, showcasing the boundless potential of this exciting field.

Biological Engineering Cycle Mechanical Hardware cycle Electrical Hardware cycle Software cycle Entrepreneurship cycle


The engineering cycle is the foundation of our strategy in our iGEM project. From choosing our topic of interest to lab work, we employed the engineering design thinking process. We used an organized, iterative approach that promoted creativity and improvement for our bioengineered system. Here we describe the failures, successes and iterations made during our project.

The first steps involved topic selection followed by choosing a suitable strain of bacteria for Lithium and Arsenic detection and carefully creating the genetic circuit that powers our biosensor. This was followed by the hard calibration phase, where we made sure that the different components of our biosensor worked appropriately. By putting the various components of our biosensor through several testing, we were able to confirm its operation and therefore prepare it for practical applications. Every component of our sensor was chosen with safety and ethics in mind, highlighting ethical and responsible genetic engineering techniques. Our project's engineering flow drives continuous improvement and adaptation, ensuring our project remains on the cutting edge of synthetic biology and offers solutions to pressing challenges.


To begin with, we identified various problems within our community and ways in which we could help mitigate those problems. At this stage, intensive research was done on possible problems we could solve. After several literature review, we chose Lithium detection and mining using synthetic biology as Lithium is one of the promising industries. Looking at the product cycle of the lithium batteries, we realized these batteries end up in dumpsites after use creating another problem, environmental pollution. In addition, Lithium has just been discovered in some parts of Ghana and we intend to jump ahead to provide cheaper and sustainable means of detecting, mining and recycling lithium to prevent further damages to our environment. This influenced our decision to not only tackle Lithium detection and mining but also Lithium recycling.


Chromoproteins and fluorescent proteins as Reporters

In our project, we have strategically employed chromoproteins (CPs) as reporter genes to convert a transcriptional module into a quantifiable signal. Unlike fluorescent proteins (FPs), CPs offer several distinct advantages that align with our project's objectives. One notable advantage is the innate dark colour of CPs, making them easily discernible with the naked eye in ambient light conditions. This characteristic not only simplifies our detection process but also eliminates the need for costly and complex instrumentation, facilitating cost-effective examination. By opting for CPs as our reporter genes, we have leveraged their unique features to enhance the accessibility and practicality of our project.

Lithium sensing module

In a paper titled "Lithium-sensing riboswitch classes regulate expression of bacterial cation transporter genes" [1], the authors explored riboswitches, a genetic element, in sensing and regulating the expression of bacterial cation transporter genes related to lithium. By utilizing riboswitches, the researchers could detect the presence of lithium and subsequently control the expression of transporter genes responsible for moving cations, including lithium ions, across bacterial cell membranes. When the nhaA riboswitch detects the presence of Li+ ions it triggers the eforRed chromoprotein to be expressed thereby, indicating the presence of lithium.

Arsenic sensing module

By embracing the concept of employing an inducible promoter, we adopted, modified and improved the design from Ashesighana iGEM 2022 team, which hinged our design on a fascinating principle. This unique promoter remains in a dormant state until it encounters specific triggers, essentially waiting for an external stimulus to activate it. When the activator protein binds to the promoter in the presence of arsenite (As3+), it activates serving as an ignition for transcription. As a result, the reporter gene, amilGFP, emits a signal in the form of fluorescence (glow under blue light). This elegant mechanism offers a dynamic and controllable means of monitoring and reporting gene expression in response to arsenite exposure, a pivotal feature of our project.

Schematic of the As sending module based on the inducible promoter

Why Arsenic?

In our pursuit of a reliable and efficient method for detecting lithium, we turn to arsenic as an ideal pathfinder element. Arsenic, a well-established pathfinder for various geochemical indicators, plays a crucial role in hinting at the presence of valuable elements, including lithium. An international team of researchers found that certain geological settings with elevated arsenic concentrations often coincide with lithium deposits. This relationship is akin to the link between arsenic and gold in mineralization, where arsenic enrichment in soil minerals facilitates the binding of gold. In a similar manner, arsenic-rich geological environments appear to host elevated lithium levels, making arsenic an informative indicator for lithium prospecting. Furthermore, soil samples taken from regions with known lithium deposits frequently reveal significant arsenic levels, solidifying arsenic's status as a valuable pathfinder element for lithium. feature of our project.

Bioleaching Module

The bioleaching module utilizes acid thiobacillus ferroxidants in oxidizing iron and sulphur containing compounds. It contains tetrathionate hydrolase enzyme which catalyses tetrathionate hydrolysis. This involves sulphur oxidation to generate sulphate, elemental sulphur and thiosulfate. This module also contains high potential iron sulphur (HiPIP) and a pH resistant gene. The HiPIP has a high redox rate effective in catalysing the oxidation reaction taking place. It oxidises ferrous iron to ferric iron which further oxidises the metal sulphides in the compound thereby speeding the mineral dissolution rate to obtain lithium. Through these processes, the Lithium ions are liberated out from the compound and leached out. During the bioleaching process, hydrogen ion concentration increases thereby lowering pH hence the need for pH resistant gene.


After modelling our modules in Benchling, we sent them to IDT for synthesis. They were able to make the arsenic module, but the HiPIP and Lithium had problems. The Li and HiPIP modules failed because the sequences contained a feature that created a hairpin in the terminator, which prompted us to modify the terminator using different types of terminators from the iGEM registry. Another reason contributing to the failure was a higher GC content. To solve these issues, we did codon optimization to reduce the high GC content in the sequence and changed the double terminator to a single terminator. We resubmitted them for sequencing again. This time, they were able to make the lithium part, but the HiPIP could still not be made. Although they were able to synthesise the lithium part, there was a secondary product present in the synthesis as an impurity and as such required thorough screening for downstream application.


Sodium Alginate Concentrations

For our hydrogels, we used 2.5%, 5% and 10% of sodium alginate with 5% Calcium chloride to experiment and establish an ideal sodium alginate concentration. The 2.5% hydrogels did not form the balls as desired but rather looked like a gel. The 10% sodium alginate hydrogels formed well defined spheres. Thus, through trying out different sodium alginate concentrations we were able to determine the ideal sodium alginate concentration as 10%.

Optical Densities

Initially we started making hydrogels with bacteria at OD600 of 0.01, 0.1 and 1.00. The colour change for hydrogel balls with 0.01 OD was not clearly visible whereas that of 1.0 was more visible. In an attempt to increase visibility, we performed increased the OD and experimented with 2.00 OD, 3.00 OD and 4.00 OD. An increase in OD showed an increased intensity in the colour. However, in as much as the colour was well pronounced, it did not change over time which meant that higher OD was not ideal for our case. Having realized this, we reduced the OD to maximum of 1.5 and minimum of 0.75. This was the OD range we proceeded to use for all our subsequent experiments.


[1] White, N. H., Sadeeshkumar, H., Sun, A., Sudarsan, N., & Breaker, R. R. (2022). Lithium-sensing riboswitch classes regulate expression of bacterial cation transporter genes. Scientific Reports, 12(1). https://doi.org/10.1038/s41598-022-20695-6