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Could Cyanobacteria farms help dilute pollutants in the atmosphere

Could Cyanobacteria farms help dilute pollutants in the atmosphere


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If I understand correctly, roughly ~2.8 billion years ago cyanobacteria started pumping large amounts of oxygen into the atmosphere.

Using modern industrial processes could this be emulated by making cyanobacteria farms to help slow down the climate problem?

I also read somewhere that someone was able to genetically (or through other means) turn off the ability of a specific bacteria to reproduce causing it to produce a byproduct much more efficiently. Could this also help these "farms"?

Alternatively could we genetically strip the bacteria of all other functions other than procreating and photosynthesis? Making this bacteria live in a "bubble" would mean it wouldn't need a lot of defense mechanisms. This could make a single purpose bacteria that would be super efficient at doing this single task.


You have various questions here.

If I understand correctly, roughly ~2.8 billion years ago cyanobacteria started pumping large amounts of oxygen into the atmosphere.

The great oxygenation event was not an instantaneous process and represents a change from one equilibrium (low oxygen) to another (20% oxygen). This abundance of oxygen and organic carbon means that there is "niche" for organisms that burn up pre-existing organic carbon and use oxygen as terminal electron accept. Fermenting organisms use the organic carbon as a feedstock, but don't have oxygen so the use highly reduced organic molecules as terminal electron acceptors (less energetic), making mixed acids (sweat bacteria) or ethanol (yeast).

Using modern industrial processes could this be emulated by making cyanobacteria farms to help slow down the climate problem?

Cyanobacteria and other aerobic phototrophs convert carbon dioxide to oxygen and organic carbon they can use to make biomass. So if you had enough of these you'd need to get rid of the biomass. Responsible forestry for housing actually ticks this box (cf. vs. a mature forest, which is nearly at equilibrium where the biomass gets consumed by other organisms, else you'd had a faster growing topsoil).

I also read somewhere that someone was able to genetically (or through other means) turn off the ability of a specific bacteria to reproduce causing it to produce a byproduct much more efficiently. Could this also help these "farms"?

It is a grand challenge of synthetic biology to stop growth. It is really hard to do as "cheat" (i.e. variant that can grow faster) will dominate. Biofuel research suffers from this as the fatty acid biosynthesis pathway is highly expensive energetically and cheats eventually win despite the most complicated safeguards.

Alternatively could we genetically strip the bacteria of all other functions other than procreating and photosynthesis? Making this bacteria live in a "bubble" would mean it wouldn't need a lot of defense mechanisms. This could make a single purpose bacteria that would be super efficient at doing this single task.

The carbon will be a problem, so you'd need to make biomass or some value added compound.

Three additional points:

Green biotech

There are many "green biotech" companies out there and there is an increasing number of green chemistry awards going to biocatalysis (enzymes for a reaction) and in some cases synthetic biology processes (whole enginereered organisms for a product or intermediate). But the former field is slow at growing because it needs to compete against a century of homo/heterocatalyis (normal chemistry), while the latter needs a lot more technological innovation to improve the production chassis (e.g. cheats, slow reactions, iron-sulfur cluster over-expression and electron balance are common issues: hydrogenase is a classically cited example of a hard target with great potential).

Note that most green biotech uncouple the process and use the biomass from regular algae or plants to feed their engineered organisms, as it is easier and there are less containment issues.

Algal blooms

In the comments I mention, iron fertilisation of the oceans (a ship releasing a container size of nutrients across an oceanic crossing is make a substatial planktonic boom, which either increases fish levels or sinks and thus buries the carbon it converted into biomass). This is a curious case of huge scale and cheap algal farming. But we don't know all the details, yes we'd be turbocharging the oceans (which are barren relative to say a jungle), but we may favour toxin-releasing algae, jellyfish and imbalance fisheries and actually send to extinction others.

Bioreactor in the ISS

The Internation space station splits water to make oxygen, dumps all carbon waste outside (CO2 and… ) and has water and food shipped up. This is odd as you'd expect they would be the first to use algae to scrub CO2! However, things are changing: they are trialing an algal bioreactor, which on a larger scale will result in a near-closed loop system. However, there are many engineering and some biological issues that need to be faced.


Cyanobacteria

Cyanobacteria / s aɪ ˌ æ n oʊ b æ k ˈ t ɪər i ə / , also known as Cyanophyta, are a phylum of Gram-negative bacteria [4] that obtain energy via photosynthesis. The name cyanobacteria comes from their color (Greek: κυανός , romanized: kyanós, lit. 'blue'), [5] [6] giving them their other name, "blue-green algae", [7] [8] though modern botanists restrict the term algae to eukaryotes and do not apply it to cyanobacteria, which are prokaryotes. [9] They appear to have originated in freshwater or a terrestrial environment. [10] Sericytochromatia, the proposed name of the paraphyletic and most basal group is the ancestors of both the non-photosynthetic group Melainabacteria and the photosynthetic cayanobacteria, also called Oxyphotobacteria. [11]

As of 2014 [update] the taxonomy was under revision [1] [2]

  • Gunflintia
  • Ozarkcollenia
  • Myxophyceae Wallroth, 1833
  • Phycochromaceae Rabenhorst, 1865
  • Cyanophyceae Sachs, 1874
  • Schizophyceae Cohn, 1879
  • Cyanophyta Steinecke, 1931
  • Oxyphotobacteria Gibbons & Murray, 1978

Unlike heterotrophic prokaryotes, cyanobacteria have internal membranes. These are flattened sacs called thylakoids where photosynthesis is performed. [12] [13]

Phototrophic eukaryotes such as green plants perform photosynthesis in plastids that are thought to have their ancestry in cyanobacteria, acquired long ago via a process called endosymbiosis. These endosymbiotic cyanobacteria in eukaryotes then evolved and differentiated into specialized organelles such as chloroplasts, etioplasts and leucoplasts.

By producing and releasing oxygen as a byproduct of photosynthesis, cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere into an oxidizing one, causing the Great Oxygenation Event and the "rusting of the Earth", [14] which dramatically changed the composition of the Earth's life forms and led to the near-extinction of anaerobic organisms. [15]

Cyanobacteria produce a range of toxins known as cyanotoxins that can pose a danger to humans and animals.

The cyanobacteria Synechocystis and Cyanothece are important model organisms with potential applications in biotechnology for bioethanol production, food colorings, as a source of human and animal food, dietary supplements and raw materials.


Could Cyanobacteria farms help dilute pollutants in the atmosphere - Biology

BASF inserted a gene into a corn plant that makes it more drought-resistant. Photo: BASF

Most environmental science is focused on how to turn back the clock, not push it forward, says Ben Bostick, a geochemist at Lamont-Doherty Earth Observatory. “We think about how we can roll back our footprint, and not so much about how can we make our footprint bigger in a positive way,” he said. “But there are many examples of synthetic biology that I think actually have a lot of potential in the environment. Think of how we can help our environment just by doing things like improving the materials we make using synthetic biology.”

Synthetic biology (synbio) is the construction of biological components, such as enzymes and cells, or functions and organisms that don’t exist in nature, or their redesign to perform new functions. Synthetic biologists identify gene sequences that give organisms certain traits, create them chemically in a lab, then insert them into other microorganisms, like E. coli, so that they produce the desired proteins, characteristics or functions.

Since 2011, when I wrote a general introduction to synbio, the field has grown rapidly.

One reason for this is the development of the gene editing tool CRISPR-Cas9, first used in 2013, that locates, cuts and replaces DNA at specific locations. Another reason is how easy it has become to use the Registry of Standard Biological Parts, which catalogs over 20,000 genetic parts or BioBricks that can be ordered and used to create new synthetic organisms or systems.

In 2018, investors poured $3.8 billion and governments around the world invested $50 million into synbio companies. By 2022, the global market for synbio applications is projected to be $13.9 billion. But synthetic biology is still controversial because it involves altering nature and its potential and risks are not completely understood.

Bostick, who works on remediating arsenic contamination of groundwater by stimulating natural bacteria to produce substances that arsenic sticks to, explained that, in fact, the entire biological community that works on organisms alters biological systems all the time, but don’t change genetic material or organisms. Scientists delete enzymes, insert new ones, and change different things in order to understand the natural world “Those are standard techniques now but they’re done mechanistically,” he said. “If you want to see how a protein works, what do you do? You actually change it—that’s exactly how we have studied our environment. They are synthetic and they are biological alterations but they’re just not done with the purpose that defines synthetic biology.” Synbio is more controversial because its purpose is to build artificial biological systems that don’t already exist in the natural world.

Nevertheless, synthetic biology is producing some potential solutions to our most intractable environmental problems. Here are some examples.

Dealing with pollution

Microbes have been used to sense, identify and quantify environmental pollutants for decades. Now synthesized microbial biosensors are able to target specific toxins such as arsenic, cadmium, mercury, nitrogen, ammonium, nitrate, phosphorus and heavy metals, and respond in a variety of ways. They can be engineered to generate an electrochemical, thermal, acoustic or bioluminescent signal when encountering the designated pollutant.

CRISPR was used to give fruit flies red fluorescent eyes. Photo: NICHD

Some microbes can decontaminate soil or water naturally. Synthesizing certain proteins and transferring them to these bacteria can improve their ability to bind to or degrade heavy metals or radionuclides. One soil bacterium was given new regulatory circuits that direct it to consume industrial chemicals as food. Researchers in Scotland are engineering bacteria to convert heavy metals to metallic nanoparticles, which are used in medicine, industry and fuels.

CustoMem in the UK uses synthetic biology to create a granular material that attracts and sticks to micropollutants such as pesticides, pharmaceuticals, and certain chemicals in wastewater. And Australian researchers are attempting to create a multicellular structure they call a “synthetic jellyfish” that could be released after a toxic spill to break down the contaminants.

Preserving biodiversity

Scientists are using synthetic biology to make American chestnut trees more resilient to a deadly fungus. Photo: Joe Blowe

American chestnut trees dominated the East Coast of the U.S. until 1876, when a fungus carried on imported chestnut seeds devastated them, leaving less than one percent by 1950. To make blight-resistant trees, scientists have inserted a wheat gene into chestnut embryos, enabling them to make an enzyme that detoxifies the fungus. This chestnut tree is likely to become the first genetically modified organism to be released into the wild once it is approved by the Department of Agriculture, the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA).

Revive & Restore, an organization that uses genetic techniques to preserve biodiversity, is attempting to rescue the endangered black-footed ferret, which is susceptible to sylvatic plague. Because the domestic ferret is not, scientists are studying the possibility of finding the genes that give the domestic ferret resistance and editing them into the black-footed ferret’s genome. The research will begin with cell cultures in the lab.

Gene drives are mechanisms that spread a desired genetic trait through a population to control invasive species. A gene drive was recently under consideration to control the golden mussel, which has invaded South American and Latin American waters. After identifying the genes related to reproduction and infertility in golden mussels, scientists proposed using CRISPR-Cas9 to edit the mussel’s genome to make the females infertile. The genetically modified mussels would then be bred with wild mussels in the lab, creating modified embryos that could be released into the wild to spread infertility throughout the population. A gene drive to eliminate mosquitoes that carry malaria has worked in the lab, but no engineered gene drive has been tried in the field as yet.

This soil crust contains cyanobacteria, algae, fungi and lichens. Photo: brew books

Some scientists are also working on modifying coral genomes to give them more resistance to warming ocean temperatures, pollution and ocean acidification. Others have proposed modifying the genes of cyanobacteria that affect moisture in the soil crust of semi-desert ecosystems so that the soil retains more water and more vegetation can grow.

Feeding the world

With the world population expected to hit 10 billion by 2050, global demand for food could increase by 59 to 98 percent. Climate change impacts—higher temperatures, extreme weather, drought, increasing levels of carbon dioxide and sea level rise—are jeopardizing the quantity and quality of our food supplies.

Researchers at the University of California, San Diego discovered that when plants encounter dry conditions, they release a hormone that closes the plant’s pores in order to retain water, slows its growth and keeps the seeds dormant. That hormone is expensive to synthesize, however, so scientists worked with synthetically developed receptors in tomato plants that responded in a similar water-conserving fashion to a commonly used fungicide instead, making the plants more resilient to drought.

The Salk Institute’s scientists have identified the genes that encourage a plant’s root system to grow deeper into the soil. They plan to engineer genetic pathways to prompt deeper roots, which will enable crop plants to resist stress, sequester more carbon and enrich the soil.

Microbes that live with legumes give them the ability to convert nitrogen from the atmosphere into nutrients the plant needs to grow. However, because other plants cannot naturally assimilate nitrogen, farmers have traditionally used chemical fertilizers. The production of fertilizer, made mainly from fossil fuels, results in greenhouse gas emissions and eutrophication. As an alternative, Pivot Bio, a California company, engineered the genes of a microbe that lives on the roots of corn, wheat and rice plants to enable the microbe to pull nitrogen out of the air and feed it to a plant in exchange for nutrients. In field tests, its nitrogen-producing microbe for corn yielded 7.7 bushels per acre more than chemically fertilized fields.

Agriculture, including raising livestock, is responsible for about 8 percent of U.S. greenhouse gas emissions. Genetically modified microbes are being used to produce food that is more sustainable, ethical and potentially healthier. Motif Ingredients is developing alternative protein ingredients without animal agriculture. It uses engineered microbes to produce food proteins that can be tailored to mimic flavors or textures similar to those found in beef and dairy.

The Impossible Burger. Photo: Dale Cruse

Impossible Foods’ plant-based burger contains synthesized heme, the iron-containing molecule found in animals and plants that gives meat its bloody flavor. To make it, scientists added a plant gene to yeast, which, after fermentation, produced large quantities of the heme protein. Impossible Burger uses 75 percent less water and 95 percent less land than a regular beef burger, and produces 87 percent fewer greenhouse gas emissions.

As the demand for seafood grows globally (fishing stocks are already 90 percent overfished), so does the need for fishmeal, the protein pellets made of ground up small fish and grain that feed farmed fish as well as livestock. California-based NovoNutrients uses CO2 from industrial emissions to feed lab-created bacteria, which then produce protein similar to the amino acids fish get by eating smaller fish the bacteria replace the fishmeal, providing the fish with protein and other nutrients.

Creating greener products

Burning fossil fuels for energy accounted for 94 percent of total U.S. anthropogenic CO2 emissions in 2016, so a lot of research is aimed at creating better biofuels that don’t compete with food production, soil nutrients or space. The latest generation of biofuels focuses on engineered microalgae, which have high fat and carbohydrate content, grow rapidly and are relatively robust. Altering their metabolic pathways enables them to photosynthesize more efficiently, produce more oil, absorb more carbon, and be hardier so that their numbers can be scaled up.

The National Renewable Energy Lab is studying microalgae for biofuels
Photo: DOE

LanzaTech in Illinois identified an organism that naturally makes ethanol from industrial waste gases. After the company engineered it with “pathways” from other organisms to improve its performance, the organism is able to produce unique molecules for valuable chemicals and fuels. LanzaTech’s first commercial plant in China has produced over seven million gallons of ethanol from steel mill emissions that can be converted into jet fuel and other products.

165 million tons of plastic have trashed the oceans, with almost 9 million more tons being added each year. Synbio could provide a solution to this pollution problem, both by degrading plastic and replacing it.

In 2016, researchers in Japan identified two enzymes in a bacterium that enable it to feed on and degrade PET plastic, the kind used for water bottles and food containers. Since then, researchers around the world have been analyzing how the enzymes break down the plastic and trying to improve their ability to do so.

California-based Newlight Technologies is using a specially developed microorganism-based biocatalyst (similar to an enzyme) to turn waste gas captured from air into a bioplastic. The biocatalyst pulls carbon out of methane or carbon dioxide from farms, water treatment plants, landfills, or energy facilities, then combines it with hydrogen and oxygen to synthesize a biopolymer material. The biopolymer, called AirCarbon, can replace plastic in furniture and packaging.

Lignin is a key component of plants that, like other types of biomass, could be used for renewable fuels and chemicals. Since very few bacteria and fungi can break it down naturally, scientists have been trying for years to develop an efficient way of doing so. Now some have engineered a naturally occurring enzyme to break it down, which could eventually make it possible to use lignin for nylon, bioplastics and even carbon fiber.

The manufacturing of complex electronic devices requires toxic, rare, and non-renewable substances, and generates over 50 million tons of e-waste each year. Simon Vecchioni, who recently defended his PhD in biomedical engineering at Columbia University, is using synthetic biology to produce DNA nanowires and networks as an alternative to silicon device technology.

Vecchioni ordered synthesized DNA from a company, used it to create his own custom BioBrick—a circular piece of DNA—and inserted it into the bacterium E.coli, which created copies of the DNA. He then cut out a part of the DNA and inserted a silver ion into it, turning the DNA into a conductor of electricity. His next challenge is to turn the DNA nanowires into a network. The DNA nanowires may one day replace wires made of valuable metals such as gold, silver (which Vecchioni only uses at the atomic scale), platinum and iridium, and their ability to “self-assemble” could eliminate the use of the toxic processing chemicals used to etch silicon.

“A technology for fabricating nanoscale electrical circuits could transform the electronics industry. Bacteria are microscale factories, and DNA is a biodegradeable material,” he said. “If we are successful, we can hope to produce clean, cheap, renewable electronics for consumer use.”

The production of cement (a key ingredient of concrete) is responsible for about eight percent of global greenhouse gas emissions because of the energy needed to mine, transport and prepare the raw materials. bioMASON in North Carolina provides an alternative by placing sand in molds and injecting it with bacteria, which are then fed calcium ions in water. The ions create a calcium carbonate shell with the bacteria’s cell walls, causing the particles to stick together. A brick grows in three to five days. bioMASON’s bricks can be customized to glow in the dark, absorb pollution, or change color when wet.

Dressing more sustainably

Fast fashion has a disastrous impact on the environment because of its dyes and fabric finishes, fossil fuel use and microfiber pollution. About three-fourths of the water used for dyeing ends up as toxic wastewater, and over 60 percent of textiles are made from polyester and other fossil fuel-based fibers that shed microfibers when washed, polluting our waters.

Textile mill in Bangladesh Photo: NYU Stern BHR

French company Pili synthesizes enzymes that can be tailored to produce different colors, then integrates them into bacteria. The bacteria are then able to create pigments. Pili’s dye is produced without petroleum products or chemicals, and uses one-fifth the water of regular dyes.

Spider silk, considered one of nature’s strongest materials, is elastic, durable and soft. Bolt Threads, based in San Francisco, studied spider DNA to figure out what gives spider silk its special characteristics, then engineered genes accordingly and put them into yeast, which, after fermentation, produce large quantities of liquid silk proteins. The silk protein is then spun into fibers, which can be made into renewable Microsilk.

The risks of synbio

In the U.S., synbio chemicals and pharmaceuticals are mainly regulated by the Toxic Substances Control Act of 1976. Other synbio commercial products and applications are regulated by the EPA, Department of Agriculture, and the FDA. But do these agencies have the capacity and effectiveness to monitor synthetic biology as fast as it’s developing and changing?

As some syn bio applications are starting to move out of the lab, there are worries about its potential environmental risks. If an engineered organism, such as those used in gene drives, is released into nature, could it prove more successful than existing species in an ecosystem and spread unchecked?

Bostick noted that each synthetic biology project today is usually focused on one very specific modification. “It’s adding or altering a single enzyme, possibly putting in a series of enzymes so that it can do one thing,” he said. “Very seldom do you tweak the rest of the organism, so it’s not critical to the success of the organism and it’s not likely to run rampant. From a scientific standpoint, it’s hard to change more than one thing.”

Moreover, according to Vecchioni, most synbio research is being done by student groups through iGEM’s International Genetically Engineered Machine Competition, and every iGEM project must have a safety component—some way to turn off the gene or regulate it if it gets out.

Another concern is that the creation or modification of organisms could be used to create a disease for the purpose of bioterrorism. Vecchioni explained that the FBI is on the lookout for this. “They walk in nicely and say ‘hi, we’re watching,’” he said. “They also go to conferences and just make sure people are being smart about it.” He added that DNA synthesis companies are also on alert. “They have a library of known dangerous pieces of DNA, so if you try to order something that is known to create disease in any organism, the FBI will come knocking on your door.”

A more recent concern is that research institutes have begun setting up biofoundries, facilities that rely heavily on automation and artificial intelligence (AI) to enhance and accelerate their biotechnology capabilities. Jim Thomas, co-executive director of the ETC Group, which monitors emerging technologies, is concerned about the tens of thousands of organisms that AI is being used to create. “It raises a real safety question because if you have something go wrong, you potentially don’t understand why it went wrong,” said Thomas. “With AI it’s a bit of a black box.” He noted that most experts agree that there has to be a process for monitoring and assessing new developments in synbio.

Despite the potential risks of synbio, its potential benefits for the planet are huge. And as our environment is battered by the impacts of climate change and human activity, we need to explore all options. “We need every possible solution to even remotely get to the magnitude of change that we need to improve our world,” said Bostick.


Introduction

The present world population of about 7.2 billion is expected to cross 9.6 billion by the end of year 2050. In order to provide food to all by that times, the annual production of cereals needs a jump of about 50%, i.e., from 2.1 billion tons per year to 𢏃 billion tons per year. This onerous target puts enormous pressure on agriculture sector to achieve the food security. But such a quantum leap in food production can be achieved either by bringing more and more land under cultivation or by enhancing the productivity of cultivable land available. The first option remains a distant dream in the light of limited land and growing population. The option of increasing soil fertility and agricultural productivity with the help of better eco-friendly management tools, promises a successful food security.

The current agricultural practices are heavily dependent on the application of synthetic fertilizers and pesticides, intensive tillage, and over irrigation, which have undoubtedly helped many developing countries to meet the food requirement of their people nevertheless raised environmental and health problems, which include deterioration of soil fertility, overuse of land and water resources, polluted environment, and increased cost of agricultural production. A big question before the present day agriculture is to enhance the agricultural production to meet the present and future food requirements of the population within the available limited resources, without deteriorating the environmental quality (Singh and Strong, 2016). The sustainable agriculture practices can fulfill the growing need of food as well as environmental quality (Mason, 2003). The present philosophy of sustainable agriculture includes eco-friendly, low-cost farming with the help of native microorganisms. It also emphasizes that the farmers should work with natural processes to conserve resource such as soil and water, whilst minimizing the cost of agricultural production and waste generation that adversely affects the environment quality. Such sustainable agricultural management practices will make the agro-ecosystem more resilient, self-regulating and also maintain the productivity and profitability.

Since long, the microbes have been known to contribute to the soil fertility and sustainable green energy production (Koller et al., 2012). During the last decades, the microbial processes of green energy production have gained interest as the sustainable tool for the generation of bio-fuels, namely methane (CH4), ethanol, H2, butanol, syngas, etc. Current investigations witnessed noteworthy surge growth in the production of cyanobacterial biomass for bio-fuels, food supplements (super foods), and bio-fertilizers for safe agriculture (Yamaguchi, 1997 Benson et al., 2014). They have been classified as beneficial as well as harmless bio-agents based on their role in regulating plant productivity. In reality, these two diverse groups of microorganisms coexist in nature, and predominance of one at any point of time, depends mainly on the environmental conditions. For many years, soil microbiologists and microbial ecologists have been studying the effect of beneficial or efficient soil microorganisms for sustainable agriculture which not only contribute to soil fertility, crop growth and yield, but also improve the environment quality.

Nowadays, sustainable agriculture practices have envisaged an important role of these tiny microorganisms in achieving the food security without creating environmental problems. The recent trends of using the bio-inoculants containing beneficial soil microbes over synthetic fertilizers, insecticides, and pesticides for enhancing crop productivity is a welcome step. As a beneficial microbe, cyanobacteria could play a potential role in the enhancement of agriculture productivity and mitigation of GHG emissions (Singh, 2011 Singh et al., 2011a). Very recently, it has been proposed that cyanobacteria could be the vital bio-agents in ecological restoration of degraded lands (Singh, 2014). Cyanobacteria are the group of photosynthetic organisms which can easily survive on bare minimum requirement of light, carbon dioxide (CO2) and water (Woese, 1987 Castenholz, 2001). They are phototrophic, and naturally occur in several agro-ecosystems like paddy fields and from Antarctica to Arctic poles (Pandey et al., 2004). They fulfill their own nitrogen requirement by nitrogen (N2)-fixation, and produce some bioactive compounds, which promote the crop growth/protect them from pathogens and improve the soil nutrient status. Cyanobacteria are also useful for wastewater treatment, and have the ability to degrade the various toxic compounds even the pesticides (Cohen, 2006). A conceptual model about the role of cyanobacteria in sustainable agriculture and environmental management has been proposed (Figure 1). This review highlights the role of cyanobacteria in bio-energy production, ecological restoration, agriculture and environmental sustainability.

FIGURE 1. A hypothetical model exhibiting the potential roles of cyanobacteria in sustainable agriculture and environmental management.


Acknowledgements

The authors thank J. van Arkel for help with the drawings and A. Ballot, W. van Egmond, S. Flury, E. Killer, L. Krienitz and M. Stomp for sharing their photographs. H.W.P. was supported by the US National Science Foundation and the Chinese Ministry of Science and Technology. J.M.H.V. was supported by Amsterdam Water Science, which was funded by the Amsterdam Academic Alliance.

Reviewer information

Nature Reviews Microbiology thanks B. Neilan, B. Qin and the other anonymous reviewer(s) for their contribution to the peer review of this work.


What are harmful algal blooms?

Harmful algal blooms are overgrowths of algae in water. Some produce dangerous toxins in fresh or marine water but even nontoxic blooms hurt the environment and local economies.

What are the effects of harmful algal blooms?

Did you know?

Climate change might lead to stronger and more frequent algal blooms.
Find out how.

What causes harmful algal blooms?

Nutrient pollution from human activities makes the problem worse, leading to more severe blooms that occur more often.

What you can do to help

The following links exit the site Exit

Volunteer to monitor waterbodies for algal blooms

Report suspected algal blooms to your state

State departments of health or environment are the best sources for local information about harmful algal blooms.

Help prevent nutrient pollution

Simple actions around your home and yard can make a big difference


CHAPTER 6 - Biological Solutions

Biological solutions to problems in environmental engineering often involve engineers integrating apparently disjointed biological knowledge, and tailoring this knowledge to address specific engineering challenges. This chapter describes how the emerging discipline of environmental biotechnology contributes to the field of environmental engineering. Biological solutions help in assessing the risk to human health and determining the effectiveness of environmental engineering design decisions to reduce this risk to an acceptable level for the least possible cost. Molecular biology-based forensic tools are increasingly used by researchers in environmental engineering to address the problem of identifying the source of microbiological pollution for Section 303d waters. This emerging field of microbial or bacterial source tracking (MST or BST) often relies upon molecular biology-based assays to identify specific microorganisms and to link environmental microbiological pollution to its source. Wastewater treatment plants are also a biological solution to the problem of highly concentrated organic pollution. In such wastewater treatment plants, the processes of microbial degradation of organic waste with biomass production followed by sedimentation are encouraged to occur in a highly controlled environment. In the past 10 years, environmental engineers have collaborated with microbiologists to develop alternative technologies for total nitrogen removal that avoid some of the inefficiency of nitrification followed by denitrification. The alternative biological solution to total nitrogen removal is known as anaerobic ammonia oxidization (ANAMMOX). In the ANAMMOX process, specific populations of microorganisms couple the reduction of nitrite to the simultaneous oxidization of ammonia to produce dinitrogen gas.


Water Quality and Sustainability

4.8.5.2.1.3 Climate impact

Cyanobacteria are a type of prokaryote. Outbreaks only occur when the population of cyanobacteria per unit of water increases drastically. The growth profile of cyanobacteria presents an S-shape curve, which indicates that a certain amount of time is needed for single cells and groups to develop. Environmental conditions, especially water temperature, significantly impact their growth rate. Cyanobacteria tend to become overpopulated at certain temperatures. Otherwise, the growth rate is inhibited and the population size remains low. In this way, climate plays an important role in early period of cyanobacteria growth. Zheng et al. (2008) reported that cyanobacteria outbreaks readily occurred over periods of 30 days during which sufficient nutrients were available, temperature remained above 18 °C, active accumulated temperature remained above 370 °C·d, weak wind conditions, and more than 208 h of sunlight. However, climate conditions such as high relative humidity, precipitation, and wind speed do not influence cyanobacteria outbreaks remarkable. Generally, July and August in the Taihu lake basin is usually favorable to cyanobacteria outbreaks.


DNA Tests Could Help Predict, Prevent Harmful Algal Blooms

A paper published in the current issue of the International Journal of Environment and Pollution, explains how a DNA test can be used to detect harmful algal blooms across the globe. The approach outlined could help reduce the economic impact on fisheries, recreational activities, and aquaculture sites, such as salmon and shellfish farms, and pearl oyster farms.

It could also help decrease the outbreaks of food poisoning due to contamination of seafood by the toxins some of these algae produce.

Senjie Lin, an Associate Professor of Molecular Ecology in the Department of Marine Sciences, at University of Connecticut, explains that the geographic extent, frequency, intensity, and economic impact of harmful algal blooms have increased dramatically in recent decades throughout the coastlines of the world. It is possible, he suggests, that this increase is partly due to greater awareness and better monitoring technology.

However, factors such as climate change and increasing levels of pollution are more likely to blame for algal bloom occurrences. Ironically, says Lin, aquaculture operations themselves are often the cause of algal blooms because of the large mass of concentrated waste products from cultured animals.

Algae include cyanobacteria, dinoflagellates, diatoms, raphidophytes, haptophytes, and various other species many of which produce potent toxins. Some, however, are hazardous simply because of the unusually high biomass they produce along a coastline, lake, or other body of water. It was recently estimated that annual economic losses due to algal blooms in the USA alone runs to tens of millions of dollars.

"To minimize economic and environmental impacts, an early warning detection system is needed," says Lin. He has reviewed the two molecular biology techniques that are most commonly used to detect harmful algae, with the putatively toxic dinoflagellate Pfiesteria piscicida as a case study.

Lin's paper provides practical information on the technical aspects of using biological markers - DNA or RNA - to detect the algae quickly and easily without the need for highly sophisticated methods or equipment. Crucial to success is the development of a portable device that could be used on board research vessels or fishing vessels equally as well.

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Role of microalgae and cyanobacteria in wastewater treatment: genetic engineering and omics approaches

Emergence of pollutants in wastewater, expensive cultivation of microalgae, and difficulties in industrial scale production are the main challenges for successful coupling of microalgae with wastewater. Nitrogen, carbon, and phosphorus in wastewater are deliberately consumed by microalgae and cyanobacteria for their growth and could act as green technology for wastewater treatment. In this review, the role and mechanistic approaches of microalgae and cyanobacteria for removal of various (in)organic compounds from wastewater have been thoroughly addressed. Distinct pathways have been reported for improving wastewater treatment technologies through large-scale cultivation of microalgal. The techno-economic feasibility and major commercial production challenges along with genetic engineering research have been addressed. A biorefinery approach with integrated biology, ecology, and engineering would lead to a feasible microalgal-based technology for various applications.

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Household products can really pollute the air

Everyday products like these emit a bouquet of chemicals that contribute vapors into the air. A spritz of cleanser or spray of some disinfectant will have a small effect. Frequent use of these products by millions of people, however, can really pollute the air.

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February 27, 2018 at 6:45 am

AUSTIN, Texas — Families wanting to reduce their impact on air pollution might need to do more than trade in a gas-guzzling car, a new study reports. It found that simple household items also are dirtying urban air. One example: those nicely scented air fresheners.

Paints, cleaning supplies and personal care products (think deodorants and hair sprays) are among common products that send a host of chemicals into the air. These air pollutants — some of them sweet smelling — now contribute as much to lung-irritating ozone and to tiny airborne particulates as does the burning of gasoline or diesel fuel.

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It might not seem that way, but the finding is a mark of success, says Brian McDonald. He is a chemist at the Cooperative Institute for Research in Environmental Sciences in Boulder, Colo. He also was an author of the new study. And he shared some of his team’s findings February 15 during a news conference. It took place here, at the annual meeting of the American Association for the Advancement of Science. His group’s data also were published February 16 in Science.

Steps to clean up car exhaust over the past few decades have had a huge effect, says McDonald. As a result, he notes, in cities “the sources of air pollution are now becoming more diverse.”

Spyros Pandis works at Carnegie Mellon University in Pittsburgh, Pa. He’s a chemical engineer who did not take part in the study. “When you have a big mountain in front of you,” he explains, “it’s difficult to know what lies behind it.” Now that big sources (such as traffic emissions) are falling, other sources become more visible.

The new study focused on a class of pollutants known as volatile organic compounds. Most are derived from petroleum or other fossil fuels. These VOCs are hundreds of diverse chemicals that easily evaporate. These gases then may linger in the air.

Some VOCs can be harmful when directly inhaled. Bleach and paint fumes make people lightheaded, for example. But beyond their immediate effects, VOCs also can react in the air with other chemicals. (These include oxygen and nitrogen oxides, largely from vehicle exhaust.) Those reactions can create ozone as well as fine particulates. High levels of fine particulate, tiny dustlike motes, can make it hard to breathe. They also can help foster chronic lung problems, diabetes and heart disease. (And while ozone high in the atmosphere helps shield earth from the sun’s harmful ultraviolet rays, at ground level it mixes with fine particulates to brew up breath-choking smog.

For six weeks, the researchers collected air samples in Pasadena, Calif. This was at a site in the well-known smoggy Los Angeles valley. They also studied indoor air measurements made by other scientists. The team traced the VOCs in these air samples to their original sources. To do this, they used databases showing the particular VOCs released by different household products.

Those household products had an outsized effect on air pollution, the team now reports. By weight, people use about 15 times more gasoline and diesel compared with VOC-emitting goods, such as soaps, shampoos, deodorants, air fresheners, glues and cleaning sprays. Yet those household products were responsible for 38 percent of the VOC emissions, the researchers found. That amount is 6 percentage points higher than the share due to gasoline and diesel use. The VOCs from household products also contributed as much as the fuels did to the production of ozone and fine particulates.

VOC-emitting consumer products

  • Shampoo
  • Hairspray
  • Deodorant
  • Perfume
  • Air fresheners
  • Cleaning sprays
  • Laundry detergent
  • Disinfectant wipes
  • Hand sanitizer
  • Glue
  • Paint

Power Words

American Association for the Advancement of Science Formed in 1848, it was the first permanent organization formed to promote the development of science and engineering at the national level and to represent the interests of all its disciplines. It is now the world&rsquos largest such society. Despite its name, membership in it is open to anyone who believes &ldquothat science, technology, engineering, and mathematics can help solve many of the challenges the world faces today.&rdquo Its members live in 91 nations. Based in Washington, D.C., it publishes a host of peer-reviewed journals &mdash most notably Science.

annual Adjective for something that happens every year.

atmosphere The envelope of gases surrounding Earth or another planet.

bleach A dilute form of the liquid, sodium hypochlorite, that is used around the home to lighten and brighten fabrics, to remove stains or to kill germs. Or it can mean to lighten something permanently, such as: Being in constant sunlight bleached most of the rich coloring out of the window drapes.

chemical A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chemical engineer A researcher who uses chemistry to solve problems related to the production of food, fuel, medicines and many other products.

chronic A condition, such as an illness (or its symptoms, including pain), that lasts for a long time.

compound (often used as a synonym for chemical) A compound is a substance formed when two or more chemical elements unite (bond) in fixed proportions. For example, water is a compound made of two hydrogen atoms bonded to one oxygen atom. Its chemical symbol is H2O.

database An organized collection of information.

diabetes A disease where the body either makes too little of the hormone insulin (known as type 1 disease) or ignores the presence of too much insulin when it is present (known as type 2 diabetes).

diesel fuel Heavier and oilier than gasoline, this is another type of fuel made from crude oil. It&rsquos used to power many engines &mdash not only in cars and trucks but also to power some industrial motors &mdash that don&rsquot rely on spark plugs to ignite the fuel.

engineer A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.

environmental science The study of ecosystems to help identify environmental problems and possible solutions. Environmental science can bring together many fields including physics, chemistry, biology and oceanography to understand how ecosystems function and how humans can coexist with them in harmony. People who work in this field are known as environmental scientists.

evaporate To turn from liquid into vapor.

exhaust (in engineering) The gases and fine particles emitted &mdash often at high speed and/or pressure &mdash by combustion (burning) or by the heating of air. Exhaust gases are usually a form of waste.

fine particulates See particulates.

fossil fuel Any fuel &mdash such as coal, petroleum (crude oil) or natural gas &mdash that has developed within the Earth over millions of years from the decayed remains of bacteria, plants or animals.

nitrogen oxides Pollutants made up of nitrogen and oxygen that form when fossil fuels are burned. The scientific symbol for these chemicals is NOx (pronounced &ldquoknocks&rdquo). The principle ones are nitric oxide (NO) and nitrous oxide (NO2).

organic (in chemistry) An adjective that indicates something is carbon-containing a term that relates to the chemicals that make up living organisms.

oxide A compound made by combining one or more elements with oxygen. Rust is an oxide so is water.

oxygen A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

ozone A colorless gas that forms high in the atmosphere and at ground level. When it forms at Earth&rsquos surface, ozone is a pollutant that irritates eyes and lungs. It is also a major ingredient of smog.

particulate A tiny bit of something. A term used by pollution scientists to refer to extremely tiny solid particles and liquid droplets in air that can be inhaled into the lungs. So-called coarse particulates are those with a diameter that is 10 micrometers or smaller. Fine particulates have a diameter no bigger than 2.5 micrometers (or 2,500 nanometers). Ultra-fine particulates tend to have a diameter of 0.1 micrometer (100 nanometers) or less. The smaller the particulate, the more easily it can be inhaled deeply into the lungs. Ultra-fine particulates may be small enough to pass through cell walls and into the blood, where they can then move throughout the body.

petroleum A thick flammable liquid mixture of hydrocarbons. Petroleum is a fossil fuel mainly found beneath the Earth&rsquos surface. It is the source of the chemicals used to make gasoline, lubricating oils, plastics and many other products.

pollutant A substance that taints something &mdash such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

smog A kind of pollution that develops when chemicals react in the air. The word comes from a blend of &ldquosmoke&rdquo and &ldquofog,&rdquo and was coined to describe pollution from burning fossil fuels on cold, damp days. Another kind of smog, which usually looks brown, develops when pollutants from cars react with sunlight in the atmosphere on hot days.

ultraviolet A portion of the light spectrum that is close to violet but invisible to the human eye.

urban Of or related to cities, especially densely populated ones or regions where lots of traffic and industrial activity occurs. The development or buildup of urban areas is a phenomenon known as urbanization.

volatile organic compounds (VOCs) Certain solid and liquid chemicals that evaporate (become gases), often at room temperature or lower. Many of these chemicals can be harmful if inhaled or allowed to move through the skin. Concentrations of these chemicals tend to be higher indoors than out. Sources of VOCs include numerous household products, such as paints, varnishes, waxes, oil-dissolving solvents, cleansers, disinfecting, cosmetics, degreasers and glues. Many fuels also release VOCs.