Welcome to the project description page of the Hydro Guardian, the Hannover iGEM 2024 team. Explore how we're harnessing the power of synthetic biology to tackle the global challenges of antibiotic and metal residues and create sustainable solutions for the future.
A significant environmental crisis is unfolding beneath the surface of our daily lives. It is contaminating our rivers, lakes, and even the water we drink. The byproducts of modern agriculture, medicine, and industry are antibiotic and heavy metal residues. These contaminants are increasingly contaminating aquatic ecosystems and the environment that depends on these ecosystems. The contaminants primarily originate from pharmaceutical manufacturing, hospital and agricultural wastewater, and industrial runoff, but also form our own daily behavior. Once released, they do not degrade easily. This inevitably leads to their accumulation in the environment and their entry into the food chains of humans and other living organisms.
Next to their high toxicity, heavy metals are known to cause severe environmental and health problems with prolonged exposure, even at low concentrations. Heavy metals accumulate in living organisms through bioaccumulation instead of breaking down over time. Studies have shown that heavy metals affect cellular structures and interact with cell components, and that some heavy metals like lead, mercury, and cadmium are hazardous even at low levels.Text
Antibiotics, essential for treating bacterial infections, have become major environmental contaminants due to their extensive use and potential improper disposal. When antibiotics enter natural water systems, they can have a big impact on the sensitive natural equilibrium. Microbial communities can be disrupted, and antibiotic-resistant bacteria fostered due to the presence, undermining the effectiveness of vital medical treatments. TextTextTextText
We must address the role these contaminants play in the development of antibiotic resistance. There is no doubt that the presence of antibiotics in the environment exerts clear and decisive selective pressure on bacterial populations, promoting the survival of resistant strains. Furthermore, co-selection (co-resistance or cross-resistance) can occur when bacteria exposed to heavy metals develop resistance mechanisms that also provide resistance to antibiotics, thereby exacerbating the spread of multi-resistant pathogens. TextText
The current solutions, such as conventional filtration and water treatment methods, are insufficient for addressing this complex problem. Many wastewater treatment plants face challenges due to insufficient infrastructure for effectively removing antibiotic and heavy metal contaminants. This allows these pollutants to persist in the environment and continue to pose risks to both ecosystems and human health.Text This highlights the urgent demand for sophisticated detection and remediation technologies, which can accurately identify and quantify these contaminants before they cause irreparable harm.
It is therefore essential to implement continuous monitoring and detection of both heavy metals and antibiotic residues in liquid samples in order to protect human health and the environment. Despite the existence of feasible methods, there is a necessity for the development of advanced technologies that can overcome the limitations of conventional approaches. In particular, this is true given that heavy metals and antibiotics are also known to directly interact with each other, causing co-selection and antibiotic-metal complexes (AMCs) with a bioactivity profile and physicochemical properties different to non-complexed residues. TextWe are dedicated to pursuing innovative solutions that directly confront the challenges posed by antibiotic and metal residues. To address the contamination of water by antibiotics and heavy metals, we must adopt a multidisciplinary approach and drive innovation. Our sensor technology is a game-changing advancement in this effort. It provides the precise and reliable means of detecting these contaminants. By enabling early detection and accurate monitoring, we will better protect our ecosystems and public health from the long-term consequences of these pollutants.
We are thrilled to introduce the Hydro Guardians project, which will develop a revolutionary cellular sensor based on mammalian HEK cells. This cutting-edge technology will detect a range of heavy metals and antibiotic residues in liquid samples early. This incredible sensor is designed for extremely precise and fast detection. It also creates a synthetic-biological basis for the further development of previous detection approaches! The sensor uses genetically modified cells that convert residues into visual signals. These cells react to specific heavy metals or antibiotics, making them highly sensitive indicators. Based on our innovative concept, we are convinced that this sensor will significantly speed up detection and help us issue early warnings about harmful contaminants in food, drinking water, and the environment.
The contamination of water resources represents a pervasive and multifaceted threat to the health of our planet's vital waterways. The sources of this contamination are as diverse as they are insidious, with antibiotics and heavy metals representing two of the most concerning pollutants. A comprehensive understanding of these sources is indispensable for the development of effective solutions to safeguard the environment.
The contamination of water with antibiotics has become a significant environmental concern, with a variety of potential sources. These include the pharmaceutical manufacturing, medical usage and waste, agricultural practices and household disposal and personal care products. The introduction of antibiotics into aquatic systems can disrupt the natural balance of ecosystems and pose a risk to human health.
Heavy metals are another major source of water pollution, with severe impacts on both water quality and ecosystem health. The contamination with heavy metals is the result of a number of significant sources like industrial discharges, mining operations, agricultural runoff and atmospheric deposition, each of which contributes to the pervasive presence of these toxic elements in aquatic environments.
By recognizing and addressing these diverse sources of water pollution, we can work toward more effective strategies for protecting our vital water resources.
The presence of antibiotic and metal residues in aquatic environments represents a significant environmental and public health concern, given their harmful impact on ecosystems and human health. These pollutants, which are commonly found in water bodies around the world, have the potential to cause significant disruption to the ecological balance, endanger biodiversity, and contribute to the growing issue of antibiotic resistance. The interaction between these pollutants amplifies their effects, rendering them particularly challenging to address. Addressing this issue directly contributes to the Sustainable Development Goals (SDGs), particularly SDG 6 (Clean Water and Sanitation) and SDG 14 (Life Under Water), as it involves safeguarding water quality and protecting aquatic ecosystems from pollution. We highlight this focus on sustainability and its link to the SDGs on our Sustainable page.
The introduction of antibiotics into waterways can have unintended consequences, including the disruption of beneficial microbial communities that are involved in essential nutrient cycling processes. Even low concentrations, which are often found in wastewater, have the potential to alter microbial populations and disrupt ecosystem stability, which can result in adverse effects such as algal blooms and oxygen depletion. TextTextTextA significant concern is the emergence of antibiotic-resistant bacteria, which is facilitated by the selective pressure exerted by antibiotic residues. The transfer of resistance genes from antibiotic-resistant bacteria to other bacteria, including pathogens, has the potential to exacerbate the global antibiotic resistance crisis.TextTextFurthermore, the direct harm caused by antibiotics to aquatic organisms, such as fish and algae, can lead to a reduction in biodiversity and ecosystem productivity. TextText
Heavy metals have the potential to be highly toxic to aquatic life, with the capacity to affect enzyme function, respiration, and reproduction. Furthermore, they can induce oxidative stress by generating reactive oxygen species (ROS) within cells, which can result in cellular damage, inflammation, and apoptosis. This oxidative stress can have significant consequences for the health of aquatic organisms, including reduced growth rates, compromised immune systems, and increased mortality. TextHeavy metals can also bioaccumulate in the tissues of aquatic organisms, thereby biomagnifying up the food chain and posing significant risks to top predators and humans. Bioaccumulation occurs when organisms absorb metals at a rate that exceeds their capacity for elimination, resulting in an accumulation of these substances within the body over time. Beyond that, heavy metal contamination can result in long-term ecological damage, as top predators often serve as critical species in maintaining ecosystem balance. Text
The combined toxicity of antibiotics and metals is greater than the sum of their individual effects, resulting in more severe ecological damage. For example, studies have demonstrated that the presence of copper can enhance the uptake of antibiotics by bacteria, resulting in more pronounced disruptions in microbial communities and greater ecological damage. Text
Furthermore, metals can facilitate the co-selection of antibiotic resistance genes in bacteria, leading to the emergence of multi-resistant bacteria and complicating the management of antibiotic resistance. The dissemination of these co-selected resistance genes represents a significant challenge to public health, as it complicates the control of antibiotic resistance and elevates the risk of infections in humans that are resistant to treatment. TextText
To better understand and predict these interactions, our team has developed a comprehensive model that integrates the effects of both heavy metals and antibiotics on bacterial communities. By combining biological data with computational simulations, our model provides valuable insights into the complex dynamics of contaminant interactions and their long-term effects on ecosystems and public health. For more information on the model and its implications, please visit our Model page.
The presence of antibiotic and metal residues in the environment represents a significant public health and ecological concern, underscoring the urgent need for accurate and reliable detection methods.
Traditional chemical analysis techniques are highly sensitive and precise, enabling the detection of trace contaminants. Despite their precision, these techniques present significant challenges, including high costs, labor-intensive procedures, and the requirement for highly trained personnel. The complexity of sample preparation and the lengthy analysis times further complicate their use, making them less feasible for routine monitoring, especially in resource-constrained settings. TextTextTextText
Spectroscopic and electrochemical methods often offer a balance between sensitivity and ease of use, making them suitable for routine analysis in controlled environments. However, they require extensive calibration, trained personnel and sophisticated equipment, which limits their application in resource-limited areas. TextTextText We therefore carried out various Spectroscopic Analyses to compare our biosensor with existing methods of contaminant detection and to provide information for the design and learn sections of the iGEM engineering cycle.
Biosensors have emerged as a promising alternative for the detection of antibiotic and metal residues, offering faster and more user-friendly analysis through the use of biological components. While they allow for real-time analysis and can be more cost-effective, the sensitivity and specificity of biosensors vary widely. Nevertheless, they can have a high specificity and sensitivity with low detection limits. An easy-to-use application and a minimal sample preparation can lead to good usability in various non-laboratory environments. TextTextText
These advances must be combined with innovative solutions that combine the accuracy of traditional methods with the simplicity and cost-effectiveness of newer technologies. Current methods are scientifically robust but impractical for widespread use, especially in areas most affected by contamination. Developing such solutions is not only a scientific challenge but a moral imperative. It is crucial for enabling effective environmental monitoring and timely intervention to protect public health and ecosystems. TextTextTextText
The emergence and spread of antibiotic resistance is a major global health threat. While antibiotic use is considered to be the primary driver of resistance, there is growing evidence that exposure to metals can also contribute to antibiotic resistance through co-selection mechanismsTextText.
Cross-resistance between metals and antibiotics refers to a phenomenon where bacteria that develop resistance to heavy metals, such as copper, zinc, or mercury, also exhibit resistance to certain antibiotics, even without prior exposure to these antibioticsText. For metals and antibiotics, the principal mechanisms include:
Our project addresses the challenge of cross-resistance by integrating two advanced biological systems: Metal-Responsive Transcription Factor 1 (MTF-1) and the PknB protein kinase. MTF-1 is a key component in detecting metal-induced stress and regulating gene expression related to metal resistance, while PknB, a serine/threonine kinase from Staphylococcus aureus, facilitates the detection of β-lactam antibiotics through its PASTA domains. By incorporating these systems into our biosensor, we can monitor the presence of heavy metals, antibiotics and their interactions, including the formation of AMCs. This integration provides a comprehensive approach to understanding and mitigating the complexities of cross-resistance in contaminated environments.
Our team has developed an innovative cellular sensor to prevent the spread of heavy metals and antibiotics at an early stage and counteract the formation of resistance. This sensor is able to detect β-lactam antibiotics and heavy metal residues in water. We chose to base our sensor on HEK (Human Embryonic Kidney) cells due to their high transfection efficiency and proven ability to show fast and precise responses to external stimuli.
By integrating the antibiotic-detecting PASTA domain from Staphylococcus aureus and the Metal-responsive Transcription Factor-1 (MTF-1), which is conserved in many organisms from insects to vertebrates, we hope that our cellular sensor can detect heavy metals and antibiotics at an early stage to effectively counter their spread.
Developing a biosensor that can simultaneously detect antibiotics and heavy metals is crucial for addressing two major environmental and public health concerns. Antibiotic contamination in water and soil contributes to the rise of antibiotic-resistant bacteria, which poses a serious threat to human health. Meanwhile, heavy metal pollution from industrial activities can lead to toxic accumulation in ecosystems and food chains, causing adverse health effects. A dual-detection biosensor would enable comprehensive monitoring of these contaminants, facilitating timely interventions and promoting safer environments and healthier populations.
The PASTA (penicillin-binding-protein and serine/threonine kinase-associated) domain is an important structural component in certain proteins that is characterised by its ability to recognise and bind β-lactam compounds.Text Our approach uses the PASTA domains of the kinase PknB to construct a sensor that can detect the presence of antibiotics in the environment.
PknB is a eukaryote-like serine/threonine kinase in Staphylococcus aureus that consists of an N-terminal cytosolic kinase domain, a central transmembrane domain and three C-terminal extracellular PASTA domains.Text When this extracellular domain recognises β-lactam compounds, it transmits the signal by autophosphorylating the N-terminal kinase domain, thereby activating downstream signalling cascades.Text In S. aureus, this mechanism normally enables early recognition and adaptation to antibiotic stress.Text
In our project, we introduce PknB into HEK cells, together with three proteins that can be phosphorylated by PknB. This targeted phosphorylation increases DNA binding activity Text and induces the expression of a specific gene, which generates a fluorescent signal. To ensure the functionality of our sensor, we have chosen three different proteins that have been shown to be phosphorylated by PknB. These proteins are two transcription factors from S. aureus GraR and CcpA TextText, as well as the human transcriptional activator ATF-2.Text To demonstrate antibiotic detection, we also designed a highly active promoter and introduced it into the cells, which enables us to measure the activation of gene expression by means of a fluorescent signal.
We utilise MTF-1 as a key component for the innovative cellular metal sensor. MTF-1 (Metal-responsive Transcription Factor-1) is an important transcription factor that plays a crucial role in the recognition and cellular response to heavy metals as well as in the maintenance of normal metal homeostasis.TextText In response to heavy metals such as cadmium, zinc and copper, MTF-1 induces the expression of metallothioneins and other genes involved in metal homeostasis.Text
MTF-1 is known as a nucleocytoplasmic shuttle protein, which under normal conditions is present in both the nucleus and the cytoplasm, but accumulates in the nucleus upon accumulation of heavy metals. There it binds to promoters that contain a metal-reactive element (MRE) and thus specifically regulates gene expression.TextText This regulatory ability allows MTF-1 to control cellular adaptation to various stress conditions, especially during exposure to heavy metals, but also during hypoxia or oxidative stress.Text
For our project, we have introduced MTF-1 into HEK cells together with a designed highly active promoter with a specific fluorescent target gene whose expression is induced by the activation of MTF-1. Through this method, we were able to generate a fluorescent signal that allows us to accurately measure the presence and concentration of metal ions in the environment.
In addition to the cellular approach, we employed controlled studies to evaluate the functionality and complexation of metals with antibiotics. Through spectroscopic investigations via Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR), as well as our own development of a sensor using light-based detection via Whispering Gallery Modes (WGM), we have further developed and expanded the biological measurement data. You can read more about this on our Spectroscopy Analysis page.
Furthermore, we developed a comprehensive mathematical and computational model to understand the interplay between heavy metals and antibiotics in promoting the spread of antibiotic-resistant bacteria, specifically E. coli, which can be used immediately by using our Inlay in the wiki. For a detailed look at our models, see our Model page. Our model incorporates both biological and physical principles, such as diffusion and contaminant interaction kinetics, to simulate real-world environmental conditions more accurately. This model was constructed to simulate the effects of various contaminants on bacterial growth and resistance, enabling predictions about how pollutants contribute to the evolution of multi-resistant strains. It complements our biological experiments by providing a framework to test hypotheses that cannot be easily replicated in the lab, thus saving time and resources concerning the implantation of the UN’s Sustainable Development Goals (SDGs). This interdisciplinary approach bridges the gap between theoretical predictions and experimental data, providing an extensive view of how antibiotic and heavy metal residues affect ecosystems. The model's predictions help refine the parameters used in wet lab experiments, ensuring a more targeted approach to understanding microbial behavior in contaminated environments.
Our project achieves early detection of heavy metals and antibiotic residues in liquid samples and improves the understanding of the biological interactions between our sensors and substances, thereby promoting technological advancement and ethical responsibility towards environmental and human health protection. The integration of clever genetic engineering, such as eukaryotic expression of PknB or MTF-1 based metal detection, will facilitate the detection of heavy metals and antibiotics. Synthetic biology provides an ideal solution to achieve our goal of a single cellular approach for both metal and antibiotic detection. More about the possible application scenarios can be found on our Implementation page.
The previous research during our studies, as well as our Bachelor's or Master's theses in the context of implant research at the NIFE (Lower Saxony Center for Biomedical Engineering, Implant Research and Development) or at the MHH (Hannover Medical School) have revealed the challenge of resistances in the clinical environment. We quickly recognized the critical need to address the problem of water contamination. Our research for the project focused immediately on antibiotics and metals, inspired for example by previous work of the iGEM team from Frankfurt 2023. We were driven to improve the detection of these contaminants in liquid samples using synthetic biology.
Another major motivation for choosing this project was our desire to contribute to the implementation of the UN's SDGs. These goals emphasize the importance of addressing critical global challenges such as water contamination and antimicrobial resistance, both of which are central to our project. By developing a biosensor that detects heavy metals and antibiotic residues in liquid samples, we hope to create a solution that directly supports these SDGs, fostering better health outcomes and environmental protection. You can find a more in-depth discussion of the SDGs on our Sustainable page.
