In general, a biosensor can be any device, which converts certain biological processes into measurable signals, providing us relevant information. Among different alternatives, bacterial biosensors are easily produced, simple, and highly accurate devices. For these reasons, we are going to develop bacteria-based biosensors using the non-pathogenic laboratory strain Escherichia coli.
The development of this kind of biosensor has been broadly reported in the last 20 years (1). From those studies it is deduced a great potential for their use in different areas as environmental pollution detection.
Team:UPNAvarra Spain/Description
Project Inspiration and Description
Development of nitrate and heavy metal bacterial biosensors
What are biosensors?
Our Goal
We are working to create bacterial biosensors for heavy metals and nitrate detection. By means of inducible promoters and other regulatory sequences (2), we are going to create different systems in order to detect nitrate, coper, mercury and cadmium in water samples using chromoproteins as reporter genes. Production and growth of those biosensors could be achieved by a simple effective way, with common growth media and standard genetic technologies as the BioBrick assembly method.
The biosensors would be able to take different colour intensities depending on the concentration of the target substances. It is then to be proved that the variation in the color of the bacteria relates to the concentration of the heavy metal or nitrate. The mere change in color proves that our biosensor indeed reacts to the materials to be detected, but does not guarantee its utility in further real applications. In order to ensure this, we have created a mathematical model based on linear regression that confirms the linearity of the color-concentration relationship. By testing linear models in different biosensors (for different heavy metals or nitrate), we confirm, experimentally, that our biosensors take a color which linearly depends on the concentration. Hence, they stand as good candidates to be used in devices for real-world water pollution detection and quantification.
The biosensors would be able to take different colour intensities depending on the concentration of the target substances. It is then to be proved that the variation in the color of the bacteria relates to the concentration of the heavy metal or nitrate. The mere change in color proves that our biosensor indeed reacts to the materials to be detected, but does not guarantee its utility in further real applications. In order to ensure this, we have created a mathematical model based on linear regression that confirms the linearity of the color-concentration relationship. By testing linear models in different biosensors (for different heavy metals or nitrate), we confirm, experimentally, that our biosensors take a color which linearly depends on the concentration. Hence, they stand as good candidates to be used in devices for real-world water pollution detection and quantification.
Why
One of the most dangerous water contaminants are heavy metals. Some of them are essential elements for living organisms, but they could become an ecological hazard if exceeding certain thresholds. The presence of heavy metals in natural environments has seen a drastic increase in recent years (3). An early effect of the presence of heavy metals in the environment is the degradation of the soil, decreasing its productivity. The accumulation of heavy metals in plants and crops, over long periods of time, can also affect the natural fauna. Last, but not least, prolonged exposure to heavy metals that are toxic or carcinogenic (such as cadmium, lead, nickel, arsenic or mercury), can cause deleterious health effects in humans. For that reason, it is important to avoid the ingestion of food in contact with contaminated waters.
Nitrate is another problematic substance present in water resources that can cause a negative impact on environment and human health. Actually, diffuse pollution from agriculture is one of the main environmental problems in Europe, responsible for poor water quality. Nitrate levels in water resources have increased specifically in many areas of the world due to the rise of intensive farming. The accumulation of nitrate in surface and groundwater may cause serious illness to both wildlife and humans. It favours water eutrophication, promoting structural changes to the aquatic ecosystem, with increased production of algae and aquatic plants and depletion of fish species when the oxygen is consumed. At the same time, nitrate intake from drinking water can be direct cause of several health conditions, including methemoglobinemia, specific cancers or birth defects (4). Our region, Navarra, is not alien to this problem. Following the EU Directive 91/676/CEE, our local government has established regional laws (Orden Foral 247/2018) in order to put some areas under supervision for their potential environmental-damaging situations.
One of the main reasons encouraging us to work on this project is the lack of awareness of this issue. In general, people are not conscious of the adverse effects of this contaminants, both in the environment and human health. Maybe, because they have long-term consequences. We consider that detection and elimination of nitrate and heavy metals from the environment should be a priority in our society. It is time to start changing our future.
Nitrate is another problematic substance present in water resources that can cause a negative impact on environment and human health. Actually, diffuse pollution from agriculture is one of the main environmental problems in Europe, responsible for poor water quality. Nitrate levels in water resources have increased specifically in many areas of the world due to the rise of intensive farming. The accumulation of nitrate in surface and groundwater may cause serious illness to both wildlife and humans. It favours water eutrophication, promoting structural changes to the aquatic ecosystem, with increased production of algae and aquatic plants and depletion of fish species when the oxygen is consumed. At the same time, nitrate intake from drinking water can be direct cause of several health conditions, including methemoglobinemia, specific cancers or birth defects (4). Our region, Navarra, is not alien to this problem. Following the EU Directive 91/676/CEE, our local government has established regional laws (Orden Foral 247/2018) in order to put some areas under supervision for their potential environmental-damaging situations.
One of the main reasons encouraging us to work on this project is the lack of awareness of this issue. In general, people are not conscious of the adverse effects of this contaminants, both in the environment and human health. Maybe, because they have long-term consequences. We consider that detection and elimination of nitrate and heavy metals from the environment should be a priority in our society. It is time to start changing our future.