Abstract
Plants have amazing and significant sensing capabilities. We proposed the use of plants themselves as sensing devices to detect different compounds. Using plant promoters activated in the presence of high concentrations of CO2 we have produced Arabidopsis plants capable of acting as biosensors for this metabolite. The results obtained open new possibilities for the use of plants as biosensors for other soil or air pollutant molecules.
In this project, we also use Synthetic Biology to design new gene reporter constructions that facilitate the visualization of the response of the biosensor plant without the need for complex equipment.
In addition, we explored the use of sequences fused to the reporter protein to control its degradation once the stimulus is terminated.
The lines of our project
First line: Permanent transformation of Arabidopsis thaliana with CO2 inducible promoters fused to GFP and subsequent quantification of GFP expression.
Second line: Fusing visible reporter genes (eYGFPuv and RUBY) to the previous promoters using the Gateway technology.
Third line: Adding a proteolytic signal to the reporter gene to study its half-life using Goldenbraid cloning system.
The problem
Nowadays the growing use of technological devices is demanding more and more consumption of rare metals such as lithium (used to create batteries) and gallium (used to create electronic circuits).
Another problem is the increase in the consumption of electricity, due to the use of technological devices. This growth in electricity waste makes that the price of the kW/h is not affordable to anyone these days. As a result, any reduction of this economic waste and the environmental damage due to the consumption of energy is welcome.
The use of electricity is also harmful to the environment because unfortunately, the complete production of electricity in a renewable way is far from now.
In addition, the use of electrical sensors requires the installation of an electrical network which in a rural area is not so much affordable, and in some countries, it is practically impossible.
In the case of the CO2 sensors, there are two options, but both have their own problems. The first option is the plugged ones, which need to be connected to a power supply with these specifications: 100 ... 240 V CA, 50/60 Hz. The second option is the portable ones, which have an autonomy of 6 hours and a time of charge of 2 hours. In both cases, we can see that if we want to sense the CO2 levels, we must be in an urban area or close to one.
Another problem with the electrical sensors is the price that they cost. In the case of the CO2 sensors, the price goes from 150€ (160$ approx.) to 650€ (700$ approx.), which is not very accessible to all the society (especially to the little owners that are starting a company).
Actual situation
Nowadays the way of sensing any kind of substance is using electrical sensors, which they are totally unsustainable in the long term. As we have seen in “The problem”, electrical sensors are totally harmful to the environment by many reasons, they consume electricity (in fact this is not bad, the problem is how we produce the electricity) and they produce non-biodegradable wastes (that usually do not be recycled)
The solution that our society gives to the problem of pollution is renewable energy such as wind power, hydraulic, or solar energy. In addition, another way of producing electricity without making CO2 is nuclear energy, which produces radioactive waste.
The problem with renewable energy is that it does not meet all the demand. In Spain only 47,4 % of the produced electricity comes from renewables. In addition, at a global scale renewable energy production only reaches 23 %. This lack in the production of electricity in an ecofriendly way makes compulsory that if we want to fight against the global warming, we must reduce the waste of energy.
In addition, our society is more and more concerned about the environment and in some areas, the non-degradable substances are becoming so much popular. However, this tendence is far away from now of being a real solution.
Our proposed solution
To solve all these issues, we propose to use plants as biosensors to detect different substances of interest. This is a new solution in which we are willing to create a green, sustainable, and impactful change in the way of sensing substances. As a result, we select plants because in contrast with the electric sensors, which need a complex production process and some rare metals to produce them, plants only need water, soil and sunlight to grow.
Other reason to use plants is the low cost of production of this brand-new biosensor. In addition, as we have said previously, the electrical sensor consumes electricity, which suppose an economic cost. Besides the plants do not need reparations, which in an electrical sensor could suppose an economic waste. Also, plans are made up of organic compounds, so the biosensors that we produce, once its useful life is finished, they would become into biodegradable rubbish, which it not a problem to the environment.