Microbial fuel cells, or MFCs, are new biochemical devices where electricity production occurs by using microorganisms. The microorganisms convert organic matter into electricity by microbial electrogenesis process. 

The technique is widely applicable in the generation of sustainable electricity and the treatment of wastewater. MFC-based systems have a new range of applications, like hydrogen production, biosensor synthesis, microbial electrosynthesis, and seawater desalination.  

A microbial fuel cell has four components; anode, cathode, ion-permeable or proton exchange membrane (PEM), and external circuit. The microorganisms reside in the anode, which produces the electron. The cathode has an electron acceptor; oxygen is the most commonly used electron acceptor. 

The PEM channel transports protons from the anode to the cathode during bacterial metabolism. The external electric circuit helps transfer electrons from anode to cathode, creating an electric current.

Although highly useful as an alternative energy source, this technique has different challenges. Like low power output compared to other alternative methods, high construction and maintenance costs, and long-term stability of bacterial communities.   

Components of Microbial Fuel Cells

The basic structure of MFCs has four essential components; anode (electron generator), cathode (electron acceptor), proton exchange membrane (PEM), and external electric circuit. Here, the anode and cathode are the two essential chambers of the MFCs, separated by the PEM. The external electric circuit joins the cathode and anode to transfer electrons.  

1. Anode chamber: Anode chamber is a habitat of microorganisms (exoelectrogens) and external electrodes. Exoelectrogens are capable of releasing electrons after the consumption of organic matter. The electrons transfers to the external electrode or anode. The anode is made of conductive material like graphite or carbon. These materials also help in the attachment of bacteria to form a biofilm. 
2. Cathode chamber:  The function of the cathode chamber is to expect the electrons released from the anode. It houses an electron acceptor molecule like oxygen, ferricyanide, mercury, iron, copper, and chromium, and a cathode electrode, made up of porous material and a catalyst like platinum. The cathode helps in the reduction of oxygen from the surrounding air. The reduction reaction combines electrons and protons to form water. Although oxygen is the most common electron acceptor, other electron acceptor includes nitrogen species, permanganate, triiodide, hydrogen peroxide, carbon dioxide, vanadium, uranium, and chloroethene.
3. PEM: Proton exchange membrane separates the anode and cathode chambers. The protons generated during bacterial metabolism must travel from anode to cathode. So this membrane facilitates this transfer and prevents direct contact between the two electrodes. Commonly used membranes include Nafion.
4. External electric circuit: The external electric circuit made up of copper or titanium wires connects the anode and the cathode electrodes. This circuit helps electrons released by bacteria travel from the anode to the cathode electrode during their metabolic processes. This movement of electrons releases electric current useful in powering electrical devices. 

Working Principle of Microbial Fuel Cells

The working principle of microbial fuel cells is microbial electrogenesis. Microbial electrogenesis means the use of microorganisms to generate electrons. Once organic matter like wastewater or biodegradable material is introduced inside the anode chamber, microorganisms consume it as a food source. 

As byproducts, the electron releases during the metabolic processes. From the chamber, the electrons transfer to the anode electrode. From the anode electrode, the electrons flow to the cathode electrode through an external electric circuit. 

The commonly used electron acceptor, oxygen, present in the cathode reduces. This reduction catalyzes the combination of electrons and protons to form water. This redox reaction completes the electron transfer cycle, creating an electric current that can power various applications.

The following chemical reaction summarizes the overall process of microbial metabolism and electron transfer;

Organic matter + Microbial metabolism → Electricity + Water + CO₂  

The electric current helps in the production of electricity along with the conversion of organic matter into benign end-products. Because of this, MFCs are an attractive option for sustainable energy generation and wastewater treatment. 

The following equation shows the reduction of oxygen in the cathode chamber;

O₂ + 4H⁺ + 4e^– → 2H₂O [E_o = 1.23 V]

Types of MFCs

MFCs are of various types based on the operational principle and specific design. The most common types of MFCs are as follows:

1. Mediator-based MFCs: In this type of MFCs, redox facilitates electron transfer between the microbial biofilm on the anode and the cathode. The electrons travel from bacteria to anode with the help of the mediator. Then, the electrons are transferred from the anode to the external circuit and finally to the cathode. Although this type of MFC is efficient in electron transfer, it can increase the cost and introduce potential toxic effects.
2. Mediatorless MFCs: This type of MFCs does not rely on external redox mediators. Instead, this method used naturally occurring exoelectrogens which directly transfer electrons to the anode. The cost of this operation may be lower due to its simple designs. However, the electron transfer rate becomes slower compared to mediator-based systems.  
3. Stacked MFCs: This type of MFCs involves connecting multiple MFC units in series or parallel to increase the overall power output. The stacking can be beneficial in areas where higher power generation is required.  
4. Single chamber MFCs: In this type of MFCs, both anode and cathode electrode are present in the same chamber which is separated by ion-exchange membrane. The design of this MFCs is simple which reduces internal resistance. However, it can limit oxygen diffusion which affects the performance of the cell. 
5. Double chamber MFCs: It is the simplest and most common design of MFCs. One chamber is used as an anode and the other as a cathode, separated by PEM. Anode has the microorganism, and the cathode has an electron acceptor. 
6. Upflow MFCs: This type of MFCs are cylinder-shaped MFC. It has a cathode chamber at the top, and an anode at the bottom. Glass wool and glass bead layers help apportion both chambers. The substrate is provided at the bottom of the anode, which moves upward to the cathode and leaves at the top.

Applications of MFCs

Microbial fuel cells (MFCs) have different applications because of their unique ability to generate electricity from organic matter and ease sustainable wastewater treatment. Some of the most essential applications of microbial fuel cells are as follows:

1. Renewable energy generation: MFCs significantly contribute to the production of renewable energy. They help produce electricity from various organic waste sources like agricultural residues, municipal wastewater, and food waste. However, the power output is meager compared to conventional energy sources. Its ability to utilize waste into energy makes them attractive for specific applications, especially in decentralized settings. 
2. Wastewater treatment: The most essential application of MFCs is treating wastewater. MFCs can efficiently remove organic pollutants from wastewater while producing electricity as a byproduct. It is a bioelectrochemical wastewater treatment that is a sustainable and cost-effective alternative to traditional wastewater treatment methods. 
3. Environmental monitoring: MFCs can be a type of biosensor that can help in environmental monitoring. MFCs can be applied in natural environments or polluted sites. This application of MCFs allows monitoring changes in microbial activity and, consequently, the ecosystem’s health. Detecting changes in the electron transfer rates or microbial communities provides valuable information about environmental conditions.  
4. Bioremediation: MFCs help in the removal of organic pollutants from the environment. These are applicable in sites contaminated by hydrocarbons or heavy metals. So, it is an excellent approach for bioremediation.  
5. Desalination: Desalination is the method of removing salt from seawater or brackish water. MCFs are now used in desalination processes where wastewater treatment is combined with desalination. It helps in providing a more energy-efficient method for removing salt. 

Benefits of Microbial Fuel Cells

Microbial fuel cells (MFCs) have many benefits, which are as follows:

1. MFC helps in converting organic waste materials like wastewater, agricultural residues, or food wastes into valuable energy. 
2. MFCs can be deployed in small-scale systems in various locations, even in rural, off-grid areas. This easy availability helps in localized electricity generation.
3. The fuel source for MFC is low cost because inexpensive waste materials generate generous amounts of electricity. It can also be integrated into already existing wastewater treatment methods. 
4. MFCs contribute to maintaining environmental sustainability in multiple ways. These promote using renewable energy sources, reduce greenhouse gas emissions, and help monitor various environmental conditions. 

Challenges of MFCs

Although MFCs are a tremendous sustainable technology, they also have several challenges that must be addressed to enhance their practicality and scalability. Some of the main challenges faced by MFCs are as follows:

1. The electricity or power generated is low compared to other alternative energy source generation methods. So, it is only applicable to small-scale applications.
2. The construction and operation of MFC are costly due to the expensive materials used in the construction of electrodes and PEM. 
3. MFCs can take a long time to start because microbes must reach their peak performance. This disadvantage can hinder the efficiency of the system. 
4. The performance of MFCs depends on the stability of microbial communities due to pH, temperature, and organic loading rates. Maintaining a consistent microbial load becomes a challenge. 
5. Some compounds in the waste can be toxic to the microorganisms, which inhibits their growth in MFC. This growth inhibition can halt the whole activity. 
6. Expenses may increase with mediators and catalysts like platinum in mediator-based MFCs. 
7. Other renewable energy sources like solar and wind power provide higher output power than MFCs. This limitation can be an added challenge to convince stakeholders about its long-term potential.  

References

• Kumar, R., Singh, L. and Zularisam, A.W. (2017) ‘Microbial fuel cells: Types and applications’, Waste Biomass Management – A Holistic Approach, pp. 367–384. doi:10.1007/978-3-319-49595-8_16. 
• Ucar, D., Zhang, Y. and Angelidaki, I. (2017) ‘An overview of electron acceptors in microbial fuel cells’, Frontiers in Microbiology, 8. doi:10.3389/fmicb.2017.00643

People often request you leave feedback after experiencing something or using any product. Feedback means a reaction or report of some products used or people’s performance. The loop means repeating the same process and instructions in the same system until the process is halted.

So, a feedback loop is a process where the output of a system is fed as input to the same system, which results in a continuous cycle of information or actions. The occurrence of a feedback loop can have various contexts, including organizations, techniques, as well as individual behavior. An example of feedback loop mechanism is homeostasis in different organisms.

Another area where the feedback loop plays a significant role is climate change. In climate change positive feed loop accelerates the rate of climate change. The negative feedback loop in the case of climate change helps stabilize the pace of climate change.

Feedback loop is also termed as self-regulating loop in the living systems. The feedback loop is mainly of two types; positive and negative. In a positive feedback loop, the result of a system reinforces the input resulting in exponential growth or change. But in a negative feedback loop, a system’s output counteracts the information leading to stability or equilibrium.

It is shown that feedback loop system in case of climate change has worsen the effects.

Positive Feedback Loop

The feedback mechanism, where the mechanism’s output helps amplify the initial input, results in exponential growth. It is a self-reinforcing process. In short, the positive feedback loop is a cycle that intensifies its effect over multiple repetitions as the output enhances the input. Under different contexts, this rapid change due to the positive feedback mechnism has both; beneficial and detrimental effects.

Let us understand the beneficial effects of the positive feedback mechanism, which is seen during labor. Here, the oxytocin released from the posterior pituitary gland acts as an input or stimulant of muscle contraction for delivering the baby from the birth canal. Muscle contraction is sharper and stronger due to the release of oxytocin. The contraction intensifies as long as the baby is in the birth canal. Once the baby is out, the stimulus at the receptor ends and oxytocin production decreases, halting the muscle contraction.

Under certain conditions, a positive feedback loop has many detrimental effects. These damaging effects are observed during the formation of avalanches in the mountains and the increased rate of climate change.

Let’s discuss the detrimental effect of a positive feedback loop by studying the example of avalanches in the mountains. Avalanche is a mass of snow, ice, soil, rock, and many other materials rapidly moving downward from the hill. Avalanche formation is a feedback system. Here the small amount of snow breaking from the slope of the mountain is the output, which rapidly increases and collects other snow, ice, and different materials during the fall. The increase in size and speed results in the formation of bigger and faster-moving mass now termed an avalanche.

Negative Feedback Loop

Like a positive feedback loop system, negative feedback mechanisms use output as input for the next cycle. The output now counteracts the initial information, which can result in stability or equilibrium. In simple terms, in the negative feedback loop, the output opposes the input for maintaining balance in the system.

It is also called a balancing feedback loop. This mechanism is essential in various biological systems and regulating processes in multiple fields. The most common areas where the negative feedback loop plays an important role are body temperature regulation by homeostasis, regulation of blood glucose levels, menstrual cycle in females, and thermostat-controlled heating system. Let us develop deeper understanding on the negative feedback loop by studying two examples; regulation of blood glucose level and thermostat-controlled heating system.

Thermostat controlled heating system in a building is a great example of a negative feedback loop. Here, a target temperature is set in the system.  Once the temperature inside a room falls below the target temperature, the thermostat senses the change and turns on the heating system. Likewise, a rise in temperature above the target temperature triggers the turning off of the heating system. This cycle repeats as needed to maintain room temperature close to the set point.

The blood glucose levels in humans are regulated with the help of a negative feedback mechanism. The body releases insulin after food consumption because glucose levels rise steeply in the blood. Insulin allows cell glucose absorption from the bloodstream, reducing glucose levels to a certain threshold. This reduction of blood glucose level results in decreased release of insulin. If the blood glucose level reduces too low, another hormone, glucagon, releases that stimulates the liver to release stored glucose. This release of glucose raises blood glucose levels back to the optimal range. These explanations show the importance of a negative feedback loop for maintaining stability and balance within various systems.

Feedback Mechanism’s Role in Effects of Climate Change

The feedback system plays a significant role in amplifying and dampening the effects of climate change. Climate change occurs mainly through the increase in emissions of greenhouse gas (GHG), primarily carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). The GHG traps heat in the Earth’s atmosphere, leading to global warming.

Positive feedback loops exacerbate the warming process in climate change, but negative feedback mechanisms partially offset the warming trends.

Detailed effects of the positive and negative feedback loop in climate change are discussed in the upcoming headings.

Effect of Positive Feedback System in Climate Change

The positive feedback loop in climate change increases the rate of climate change by feeding into detrimental output as input in the ecosystem. Ice-Albedo feedback, permafrost thawing, forest loss, and carbon sequestration are some of the effects of a positive feedback loop in climate change.

1. Ice-Albedo feedback: The rise in Earth’s temperature melts glaciers and ice in the Arctic Sea. The melting reduced the planet’s surface area, which was covered by highly reflective ice (high albedo). The dark ocean water and land surfaces with low albedo are exposed, which increases the absorption of solar energy and warms the Earth even more. This warming of Earth results in the melting of more ice, creating a self-reinforcing cycle.
2. Permafrost thawing: Permanently frozen soil (permafrost) present in the Arctic and subarctic regions starts to thaw once the global temperature rises. The thawing releases a significant amount of methane and carbon dioxide, previously trapped in the frozen ground. Methane is a potent greenhouse gas that further increases global warming.
3. Forest loss and carbon sequestration: Wildfires and deforestation reduce the capability of Earth to absorb CO₂ by photosynthesis. Forests act as carbon sinks that trap CO₂ from the atmosphere and stores it as biomass. The lower the absorption of CO₂ due to the loss of forests, the higher the atmospheric CO₂ levels, increasing global warming.

Effect of Negative Feedback Loop in Climate Change

The negative feedback loop helps in the slight remediation of the effects of climate change.

1. Carbon uptake by Oceans: Oceans can absorb large amounts of CO2 from the atmosphere and act as carbon sinks. But increasing the amount of CO2 in the atmosphere results in less carbon absorption by the ocean, decreasing the efficiency of the negative feedback loop.
2. Enhanced plant growth: Increased CO₂ level enhances plant growth in some ecosystems. The plant growth can absorb more carbon from the atmosphere. Nutrient availability, water availability, and weather conditions significantly affect the effectiveness.

Although the negative feedback mechanism can slightly mitigate some climate change effects, it can be overwhelming due to the more robust positive feedback loops. For instance, the ability of oceans to absorb carbon is limited due to ocean acidification. This acidification negatively impacts the ocean ecosystems. As a result, the net effect of different feedback loops can increase the rate of global warming and its impact on various ecosystems. Effective methods of bioremediation is required for controlling climate change.

References

• Lippa, A. M., & Goulian, M. (2009). Feedback inhibition in the PhoQ/PhoP signaling system by a membrane peptide. PLoS genetics, 5(12), e1000788. https://doi.org/10.1371/journal.pgen.1000788
• Dickinson, R.E. and Hanson, B. (1984). Vegetation-Albedo Feedbacks. In Climate Processes and Climate Sensitivity (eds J.E. Hansen and T. Takahashi). https://doi.org/10.1029/GM029p0180
• Rao, S.D. and Igoshin, O.A. (2021) ‘Overlaid positive and negative feedback loops shape dynamical properties of phopq two-component system’, PLOS Computational Biology, 17(1). doi:10.1371/journal.pcbi.1008130.

Different arts represent different eras of human civilization. Art plays a significant role in understanding the lives lived by our ancestors. From stone sculptures to monumental paintings, all art relics are susceptible to environmental deterioration and degradation by microbes that grow in the illustrations.

It is well known that microbes deteriorate artworks that threaten serious damage to these pieces. But preserving these paintings and sculptures means using harsh chemicals that cause even more damage to the artworks. 

However, one can avoid biodeterioration by using the biopreservation method of art. The biopreservation of art involves using some group of microbes that feed on the grime in paintings and softening the stones. This method can help in conserving the artworks. 

Concept of Biopreservation of Art

The use of different biological materials and techniques in preserving and protecting artworks is known as biopreservation of art. Here, biological methods and different biological principles are used to preserve the art relics. These methods are helpful in showing the deterioration of art objects caused by biological agents like microorganisms, insects, and fungi. 

The condition and longevity of artifacts highly depend on biological factors. The raw material for art production is usually organic materials like paper, canvas, paint, natural dyes, or wood. These organic materials are easy targets for biological deterioration after some time. Temperature, humidity, environmental pollutants, and light exposure also aid in the decomposition of the artwork.

The biopreservation methods of art conservation includes:

1. Preventing and controlling the growth of biological degradant: As discussed earlier, the growth of harmful and degrading microbes and insects can destroy art and art materials. So, their growth must be controlled and prevented. Regularly cleaning the artwork, applying appropriate storing and displaying methods, and maintaining the right environmental conditions like temperature and humidity can aid in controlling the growth. However, this method of preventing growth applies to the internal environment. Continuous monitoring and rapid removal of problematic microbes should be done for external or outdoor environments.  
2. Using chemical and mechanical removal methods: Mechanical methods include using tools like brushes, scalpels, vacuum, and pressure to remove the contaminants from the arts. Chemical treatment includes using biocides, insecticides, and fungicides to preserve the artwork. Another method of removing contaminants is blasting the painting with lasers and gamma irradiation.   
3. Growing natural protectants: Although most microbes destroy art and artworks, some microbes can aid in conserving them. These protect the artwork by feeding on the unwanted layers from paintings or breaking down harmful substances on art objects. These are termed biocleaners.    
4. Continuous study and monitoring: There is a different biological process that causes the deterioration of the art. Constant studying and monitoring of these processes help in developing new preservation techniques. DNA analysis and microscopic observation help identify, track, and monitor the biological agents in artworks. The continuous analysis of DNA is another effective method for controlling and preventing the growth of harmful microbes in paintings and other artworks. 

Different Methods of Biopreservation of Art

There are different methods applicable for making microbes effective art protectants. Some of them are as follows:  

Bio cleaning

Using microbes to clean unwanted and degrading components from art and art relics. Microbes are applied directly in the art. The microbes metabolize the harmful deposits, including organic matter and salts. This metabolization helps in removing the stakes and helps restore the art relics. A recent article claims that Pseudomonas stutzeri strain A29 successfully cleaned nearly 400-year-old wall paintings at the Vatican Museums and Pisa Cathedral Cupola in Italy. This method is also useful is removing graffiti from different artworks.  

Bioconsolidation

Some bacteria produce calcium components that cushion the damaged stone sculptures. Bacteria like Bacillus and Desulfovbrio can create these calcium build-ups. Many studies are conducted on this preservation method, but one of the promising results was in isolated bacteria from stone blocks a the San Jeronimo Monastery in Spain. Here, they found the biomineralization capacity of different bacterial isolates and reapplied them to the stone. After two years of analysis, abundant calcium carbonate was present in the stone sculpture. This research showed that there is a chance of consolidation using native microbes. 

Growth limitation

Another way to preserve art was by analyzing the antagonistic relationship between microbes. This method uses different microbes to produce various components that can limit the growth of other microbes with a potentially high risk of deterioration. For example, Bacillus has different elements that can determine paint-dwelling harmful fungi and bacteria growth. The spores produced by Bacillus species limited the growth of fungi and bacteria isolated from a 17th-century painting. The bacteria also produce biocides and fungicides, and even after five months of study, there was no harmful effects on the mural and paintings.    

Limitations of Biopreservation   

Although biopreservation is inexpensive and effective, it has some limitations, including damage to art. 

1. Unintentional damage to art: As we discussed earlier, biopreservation uses biocides or biological agents. The agents react with different components of the art. The reaction alters the appearance of the artwork and damages the painting during these alterations. The use of appropriate treatment methods and regular testing can help avoid this limitation. 
2. Susceptible to environmental conditions: The microbes used for biopreservation can degrade under different environmental conditions like temperature and humidity. The storage and display settings are the main reasons the biopreservation method fails. So, properly storing and displaying the artworks play a significant role in the growth of microbes or the inefficacy of preservation treatments. 
3. Limited study on long-term effectivity and reversibility: This limitation states that the data on the long-term effects of biopreservation is lacking. This lack of data can lead to misunderstanding the potential risk and determining the correct method used for biopreservation. Some biocides can have irreversible effects on art forms, harming the artwork and not preserving it.    
4. Safety concerns: Bio-preservative methods can lead to health and safety issues in art handlers, conservators, and viewers. For example, spores of  Bacillus species can lead to a high risk of illness and disease in humans. Safe handling and application of biocides are necessary for providing safety to the concerned bodies. In addition, the hazardous materials, if not disposed of properly, can also lead to health risks for handlers.  

References and Further reading

• Ciferri O. (1999). Microbial degradation of paintings. Applied and environmental microbiology, 65(3), 879–885. https://doi.org/10.1128/AEM.65.3.879-885.1999 
• BARRON, M. (2021) Microbes as enemies and allies in the world of art conservation, ASM.org. Available at: https://asm.org/Articles/2021/December/Microbes-as-Enemies-and-Allies-in-the-World-of-Art 
• Ranalli, G. et al. (2019) ‘Onsite advanced biocleaning system for historical wall paintings using new agar-gauze bacteria gel’, Journal of Applied Microbiology, 126(6), pp. 1785–1796. doi:10.1111/jam.14275. 

Nutrients are essential chemical elements in food, necessary for the growth and survival of plants and animals. Nitrogen and phosphorus are particularly crucial and abundant among numerous nutrients. However, an excessive supply of it can harm water quality and biodiversity, a process known as eutrophication.

Eutrophication originates from the Greek words eutrophos, “eu” meaning well, and “trophos” meaning fed. Thus, the word eutrophication means well-fed or nutrient-rich. Further, eutrophication can be defined as a process in which a body of water, such as a lake, river, or coastal area, becomes overly enriched with nutrients, particularly nitrogen, and phosphorus, leading to phytoplankton’s plentiful growth. It has been found that more than 30% of lakes and reservoirs worldwide are affected by eutrophication. One of Nepal’s most familiar examples of eutrophication is the excess phytoplankton growth in the few lakes of Pokhara.

Causes of Eutrophication

Eutrophication can be caused by human activities or by natural phenomena. Although eutrophication is also caused by natural wonders but human activities contribute the most that are as follows;

1. Agricultural drainage: Nowadays, for productive cultivation, human uses fertilizer that is rich in nitrogen and phosphorus compound; when rain occurs, these compounds drain into the lakes or ponds. As a result, causing increasing in its nutrient that, in the end, results in eutrophication.
2. Urban drainage: Urban areas contribute to eutrophication by discharging sewage, stormwater runoff, and industrial waste. Such waste, rich in nutrients, finds its way to the water bodies.
3. Deforestation: Deforestation is a significant factor leading to soil erosion and sedimentation, transporting nutrients into water bodies and promoting eutrophication.
4. Aquaculture and Fish Farming: Using excess nutrients to cultivate fish in a lake or a pond also increases water bodies’ nutrient content, leading to eutrophication.
5. Atmospheric deposition: Emission of nitrogen from industries, burning of fossil fuel, animal breeding, etc., can be deposited into land and subsequently to water bodies. This emission results in nutrient enrichment (eutrophication).

Process of Eutrophication

Eutrophication occurs in four steps. These include;

1. Excess nutrients: The process begins by adding excessive nutrients, particularly nitrogen, and phosphorus, into a water body. This addition can occur naturally or due to human activities such as agricultural drainage, sewage discharges, industrial waste, and atmospheric deposition.
2. Algae bloom: Algae are the first organisms to take advantage of the increased nutrient availability and start to increase rapidly. This results in the overgrowth or bloom of algae in the water body. These blooms can manifest as thick green or brown mats on the water’s surface.
3. Oxygen depletion: When algae form a thick layer on the water’s surface, it blocks sunlight from entering the water and uses oxygen. Eventually, water becomes oxygen-depleted (such a condition is also known as hypoxia).
4. Dead zones: The excessive growth of algae and the subsequent oxygen depletion can negatively impact sensitive species, leading to a decline in biodiversity and the dominance of certain species adapted to high-nutrient conditions.

Types of Eutrophication

There are two main types of eutrophication: natural eutrophication and cultural (or anthropogenic) eutrophication.

Natural Eutrophication

A process occurring as a lake or river ages hundreds or thousands of years is called natural eutrophication. It happens gradually by addition of nutrients from decaying plants and animals in a water body. This type of eutrophication occurs slowly and results from the natural aging of the water body.

Cultural Eutrophication

It is a type of eutrophication that is caused by human activities and the input of nutrients. This type occurs through increased nutrients, especially nitrogen, and phosphorus, in the water body due to human activities such as fertilizer use, sewage discharge, etc. It is a rapid type of eutrophication that is accelerated by human activities.

Effects

Eutrophication causes various effects on human health, the ecosystem, socio-economic sector, which are as follows;

1. Due to the excess growth of phytoplankton, water transparency decreases, and water turbidity increases. The water may become unsuitable for drinking even after treatment.
2. Phytoplankton utilizes all of the oxygen present, which results in the depletion of oxygen content in water bodies.
3. The presence of excess nutrients in water bodies promotes algal growth. This increased growth leads to the formation of dense algal blooms on the water surface, which can reduce light penetration and limit oxygen availability for other organisms. 
4. It causes a change in the aesthetic value of the water body.
5. It causes a decrease in species diversity in the water body due to the algal bloom.
6. Some harmful algae can also produce toxins. The release of cyanotoxins by cyanobacteria is said to cause the deaths of wild animals, farm livestock, pets, fish, and birds in many countries.
7. Increased vegetation may impede water flow and the movement of boats. This prevention can lead to a loss of tourism/recreation (swimming, boating).
8. It can also lead to the disappearance of commercially important species such as trout.

Management

Eutrophication is one of the most widespread problems faced by freshwater systems that need to be controlled or managed by implementing various strategies and practices that are as follows;

1. Management of source: Nitrogen and phosphorus are significant nutrients that get excess in water bodies through human activities such as; sewage runoff and agricultural drainage. Therefore, to prevent eutrophication, best management practices in agriculture, such as reducing excessive fertilizer application, implementing buffer zones, and optimizing irrigation techniques, can help minimize nutrient runoff.
2. Application of physical and chemical methods: Several methods are introduced to control eutrophication. These methods include; the use of algicides that kill the algae, the use of chemical flocculants, and the use of modified clay (e.g., nano silicate platelets, lanthanum-modified clay, etc.). Similarly, destratification, physical removal or harvesting, and sediment dredging are also possible to control methods, although they contain the significant drawback that they are costly. 
3. Public awareness: Raising awareness among the general public, policymakers, and stakeholders about the causes and impacts of eutrophication can help foster support for implementing necessary measures.
4. Biological control: Phytoplankton can be controlled more inherently. One of the methods is using aquatic macrophytes like Eichhornia crassipes and Salvinia auriculata, which helps decrease the concentration of nitrogen and phosphorus compounds in water. Besides this, duckweed can also be used to treat wastewater.

References

1. S. R. Carpenter, D. Ludwig and W. A. Brock . Management of Eutrophication for Lakes Subject to Potentially Irreversible Change. JSTOR, 9(3):751-771, 1999.
2. T. Wagner, L.E. Erickson. Sustainable Management of Eutrophic Lakes and Reservoirs. Journal of Environmental Protection. 2017,8(4). DOI: 10.4236/jep.2017.84032

Art comes in different forms. Art refers to things that stimulate a person’s thoughts, ideas, senses, or beliefs through other senses. So, imagine using microbes and their characteristics in creating art. 

Microbes in art mean using or integrating microorganisms like bacteria, algae, and fungi into artistic practices. This sector combines the different fields of microbiology and art. 

Every year different microbiological communities organize agar art competitions with different themes. For example, the American Society of Microbiology (ASM) is organizing an ASM agar art competition in 2023 with the theme of microbiology in space.

The Concept of Microbes in Art

Microbes in art help explore the aesthetic, scientific, and conceptual aspects of microscopic life forms. There are different microbial art forms like art in agar medium, creating living sculptures, and paintings that rely on the growth and behavior of bacteria or fungi. The pigments produced by microbes are useful in making bio-dyes and bio-inks for artistic purposes.

The most common and explored form of microbes in art is agar art, where microbiologists grow bacteria or fungi using their artistic skills. Microbiological artists study the growth pattern of microbes, how these interact in their environment, and change their growth patterns. 

The artists may manipulate environmental conditions like humidity, nutrient availability, and temperatures to guide microbial artworks’ growth and visual outcome. The evolving nature of microbial art forms makes them a temporal element of the art form.      

Incorporating microbes in art has opened up exciting collaborations between artists and scientists/researchers. The partnership involves accessing scientific equipment, expertise, and cultures of microbes. Along with access to these fields, there will be increase in discussions around the ethical and safety considerations of working with living organisms. 

While making the microbial art, themes have different concepts, like the relationship between humans and microbes, highlighting the role of microbes in our body, the environment, and ecosystems. Others indulge in the invisible world of microbes, revealing microbial life’s complexity and beauty. In addition, microbial art addresses broader ecological, ethical, and social issues related to microbiology, like antimicrobial resistance or the impact of human activities on microbial communities.  

Microbes in art have opened up a unique perspective on the intersection of science and creativity. This concept has also developed many movements like DIYbio and bio art, which allow enthusiasts and artists to experiment with microbiology and genetic engineering in non-institutional settings. These movements help promote public engagement with science under ethical boundaries.  

Agar Art Competition

The participants then use bacteria or fungi’s growth patterns and colors and produce visually captivating artworks in the agar. There are things to consider before participating in the agar art competition. 

Some of the things to consider before entering the competition are the concept, procedure, themes, proper photographing, using the right microbes, understanding the criteria for judging, and safety measures. 

Concept and process

The idea of agar art combines microbiology and art; using living microbes is a priority. The method includes preparing agar plates in Petri dishes after proper sterilization. Once the agar solidifies, participant inoculate the selected microorganisms in the medium in specific patterns and shapes using sterilized tools. The microbes grow and produce colorful colonies, which are the base for the artwork.   

Participation and themes

Participation is open to diverse backgrounds, from scientists to artists, students, and enthusiasts. Anyone can compete in the contest, with specific themes in different years. The theme can range from pop culture to social issues and nature. Creativity is encouraged by incorporating various microbial species and techniques for their designs. 

Selection of microbes

Microorganisms used can be chosen by free will by the competitors. The choice must include ethical considerations, non-pathogenic bacteria, and fungi that display vibrant colors during growth. The microbial specimens commonly used are Serratia marcescens, which produces red pigment, Pseudomonas aeruginosa, which has a greenish-blue tint; Penicillium and Aspergillus are used for creating unique patterns and textures. 

Understanding the judging criteria

Different competitions have different criteria the participants are judged on. Some will value your artistic merit and creativity. Others may appreciate the technical skill, microbial growth patterns, color combinations, and overall visual impact. The competitors may also require to add descriptions about the art or inspiration behind the art and the microbial species used.    

Preventive measures

Participants should know the safety guidelines when working with microorganisms. They must adequately sterilize the equipment before and after use. They must use aseptic practices to prevent contamination or the spread of potentially harmful organisms. The disposal of the artwork should also be in a safe manner. So, following provided guidelines about preventive measures before, during, and after creating the artwork is very important. 

Photographing techniques

Although the artwork may be superb, the photographing method can make or break the chance of winning the competition. Clicking pictures under natural light instead of bright overhead lights is suggested. Natural light will prevent shadowing from phones and cameras. The background must be neutral. If the organisms were non-pathogenic and under a controlled and safe environment, the top lid might be removed to prevent the glaring effect.    

References and further reading

• ASM agar art contest: Overview. (2023). https://asm.org/Events/ASM-Agar-Art-Contest/Home  
• Tsang, J. (2021, May 3). This gorgeous art was made with a surprising substance: Live bacteria. Science. https://www.nationalgeographic.com/science/article/agar-art-contest-winners-create-gorgeous-art-from-live-bacteria  
• Sulaiman, Suraya & Wi, Wan & Othman, Mohd & Najib, Mohd. (2022). Microbial Art: An Integration of Art and Microorganisms. 
• Hunt, G., & Lontok, K. (2022, August 19). Top 5 agar art tips. ASM.org. https://asm.org/Articles/2019/September/Top-5-Agar-Art-Tips

Did you know microbes travel with you? You can easily carry microbes to any sterile environment, including space. There might be the presence of microbes in space stations and spacecraft during assembly or introduced after the arrival of new crews or payloads. 

Astro microbiology or exo microbiology is the study of microbial life in space or under conditions similar to space. To date, microbes have been studied in controlled ground-based simulations or in the international space station (ISS). 

The highly adaptable nature of microbes helps them to survive in outer space. The research on the microbes in outer space will help to understand the possibilities of life in the area. So, studying microbes in space and the effects space has on microbial colonies is essential. 

Survival of Microbes in Space

Although microbes get introduced to the space environment, the real question is, “Can microbes survive the extreme space conditions?” The answer to that depends on how adaptable the strain of microorganisms is. There has been evidence of microbial survival on spacecraft as per NASA; even after rigorous cleaning and sterilization protocols, microbial contamination has been detected.  

Some microorganisms, called extremophiles, can withstand different harsh environments. Some of the factors that help some organisms to survive the environment of space are as follows:

1. Tolerate as well as thrive in high temperatures: Thermophiles prefer and thrive in environments with extreme temperatures like hot springs or deep sea hydrothermal vents. These are the potential candidates for surviving extreme heat experiences during the launch and re-entry to space. 
2. The capacity to survive in radiation: Space is surrounded by different types of radiation, including solar and cosmic radiation. These radiations can damage DNA and other cellular components. Deinococcus radiodurans possess extraordinary resistance to radiation and can withstand exposure to high radiation levels. Due to this property, the bacteria become the perfect study group for understanding the effects of radiation on living organisms. 
3. Formation of spores: The spores formed by some microbes are resistant structures that protect the organism from harsh conditions. Bacteria, like Bacillus subtilis, have survived simulated space conditions like exposure to vacuum, extreme temperatures, and radiation. These results show that spore-forming microbes can survive the rigors of space travel.  

However, some factors like microgravity, lack of essential nutrients, and long-term exposure to vacuum can be the biggest hurdles to the survival of microorganisms in actual conditions of outer space. Although the survival of microbes in space is challenging, some have demonstrated the ability to survive and thrive in the factors. So, further research and exploration are necessary for deepening the understanding of microbial survival in space and its use in astrobiology and human space exploration. 

Importance of Microbes in Space

The research on microbes in space plays an essential role in human space exploration and astrobiology. Microbes are primitive organisms that can provide insights into fundamental aspects of life and are instrumental in understanding the universe. 

Studying microbes in space is essential for understanding the origins of life, human health in space, planetary protection, biotechnological applications, exploring extraterrestrial life, and developing advanced space exploration technology. 

1. Understanding the origins of life: Microbes are the earliest forms of life on Earth. These microbes help obtain valuable insights into the origins and evolution of life in the universe. These studies then help understand the conditions necessary for life to emerge and thrive in another environment, including other planets and the moon. 
2. Exploring extraterrestrial life: Microbes also known as primitive organisms that offer valuable models for studying the potential for life beyond Earth. Studying the survival mechanisms of microbes in space help determine the existing microbial life or signs of past microbial life. This study helps us understand the prevalence of life in the universe. 
3. Developing advanced space exploration technology: Enzymes produced by extremophiles can help build robust materials like radiation-resistant coatings or thermal-stable enzymes for molecular analysis in space. This study of the resilience and adaptability of microbes can help develop innovative technologies, enabling safer and more efficient space missions. 
4. Planetary protection: Space exploration can introduce pathogenic and destructive microbes in other celestial bodies with terrestrial microorganisms. Ensuring that the discovery of life on other planets and moons is native and not contaminated by Earth. Scientists studying microbes’ survival and dispersal mechanisms in space help form protocols and guidelines for protecting planetary bodies.  
5. Human health in space: Astronauts and scientists on space missions are potentially at risk due to changes in diet and suppressed immune systems. Developing proper sterilization and sanitation protocol helps build life support systems in ISS and spacecraft. So, it is necessary to understand the interaction between microbes and the space environment and how these affect an astronaut’s health after long-term space travel. 

Effect of Space in Microbial Colony

Some effects of space on microbial colonies are alteration in growth patterns, genetic and phenotypic changes, enhanced survival, biofilm production, , and increased antibiotic resistivity. 

1. Enhanced survival: Some microbes have been can survive extreme space conditions. The thermophiles, radiation-resistant, and spore-former can withstand the high levels of extreme conditions of other microbes. These can resist harsh conditions and grow in the space environment.   
2. Altered growth patterns: Microgravity in space has altered the growth patterns of microbial colonies. The microbial cells form compact aggregates or clumps instead of spreading out in a flat, two-dimensional manner which leads to changes in the overall structure and organization of the colony. 
3. Biofilm production: The biofilm is a complex community of microbes surrounded by a self-produced matrix. Biofilm production can alter in space due to surface interactions and reduced hydrodynamic shear forces. The changes in their properties and behaviors may be seen compared to their terrestrial counterparts.   
4. Increased antibiotic resistivity: Different studies indicate that microbial colonies may increase antibiotic resistance when exposed to space conditions. As discussed earlier, the genetic makeup of microbes changes, including the acquisition of antibiotic-resistance genes. This change can prove a challenge for controlling infections during space missions.  
5. Genetic and phenotypic changes: Space conditions like radiation can change microbial colonies’ phenotype and genetic makeup. This change can lead to mutations and alterations in gene expression and the emergence of new traits. These changes can assist in the survival and adaptation of microbes in space and influence their behavior and interactions inside the colony. 
6. Altered metabolic pathway: Due to the unavailability of nutrients, microbes may vary their metabolic activity. For example, microgravity can adversely affect nutrient uptake and utilization in microbial colonies, so they modify with the changes and use alternative energy sources. These adaptations lead to modification in their growth and behavior.  

References and Further Reading

• Dunbar, B. (2015). Retrieved from https://www.nasa.gov/exploration/humanresearch/Microbial-Creatures-in-Space.html
• Barron, M. (2022). Retrieved from https://asm.org/Articles/2022/October/Out-of-This-World-Microbes-in-Space   
• Guzman, A. (2022). Retrieved from https://www.nasa.gov/mission_pages/station/research/benefits/our-relationship-to-microbes-on-iss/   
• Mars, K. (2022). Retrieved from https://www.nasa.gov/feature/experiments-to-unlock-how-human-bodies-react-to-long-space-journeys  
• Lewis, R. (2015). Retrieved from https://www.nasa.gov/feature/microbiology