A bug’s life: Can bacteria help us clean up our messes?

Amid the climate crisis and intensifying resource stress, can these and other newly discovered superpowers help us clean up our mess?

Bacteria have made their homes since the days when Earth was still covered in lava billions of years ago. They processed harmful gases to help make the planet habitable.

They are not a magic cure though. “Working with bacteria takes time and patience, especially since certain toxic chemicals can affect bacterial growth and impair their function,” says Mukesh Dobal, a bacteria-experiment researcher and retired professor of biotechnology at the Indian Institute of Technology, Madras (IIT-M). the professor ).

But “microbes have a huge role to play in how we can combat climate change,” says Steven Ellison, a professor of ecology and evolutionary biology at the University of California, Irvine.

For example, since 2018, chemical manufacturer LanzaTech has operated a production plant that uses bacteria derived from rabbit manure to convert waste gas from steel mills (a mixture of carbon monoxide, carbon dioxide and hydrogen) into ethanol for use in cars. Ultimately, the goal is to use it in aircraft.

Richard Branson’s Virgin Atlantic has been working with LanzaTech since 2011, according to Branson’s 2016 post, to produce jet fuel from such gases.

“Companies like LanzaTech, Loam and Pivot Bio are developing microbe-powered products as commercial solutions to reduce carbon footprints,” says Nguyen K Nguyen, director of the American Academy of Microbiology.

Gemma Reguera, a professor of microbiology and molecular genetics at Michigan State University, says today’s research with bacteria is a reminder to be creative and not limited in how we see possibilities.

Reguera was part of the team that discovered Geobacter’s Iron-Man properties in 2020. “Research is the freedom to explore, to explore and explore and explore,” she says. “We have textbook opinions about what microorganisms can and should do, but life is so diverse and colorful. There are other processes waiting to be discovered. “

Some already are. take a look

suiting up

“Iron-man” bacteria are nicknamed for their ability to survive exposure to toxic cobalt by essentially making a metallic suit for themselves from that element. This is an ability discovered in 2020 by researchers at Michigan State University.

Cobalt is a precious but increasingly rare metal used in alloys for electric vehicle batteries and spacecraft. It is highly toxic to living things including humans and bacteria.

In their study, the research team details how Geobacter sulfurreducens essentially mines cobalt from minerals and metal oxides in its environment, and wraps itself in cobalt to prevent the metal from entering its cells and becoming toxic. Even high levels of cobalt exposure failed to make a dent in the suit. Microscope images showed the microbes enveloping themselves in the metal and thriving, says Gemma Reguera, a member of the research team.

This ability means bacteria can be used to extract cobalt from discarded lithium-ion batteries, for recycling or at least a more sustainable form of e-waste disposal. The researchers now plan to test whether Geobacter can absorb other toxic metals, especially cadmium, which is also prevalent in e-waste.

“The lesson is that we really need to think outside the box, especially in biology,” Reguera says. “We only know the tip of the iceberg. Microbes have been on Earth for billions of years, and thinking they can’t do anything prevents us from many ideas and applications.”

Life in plastic

In the race to find bacteria that can quickly and efficiently consume plastic, Rhodococcus rubber stands at the forefront. It busted the tape in January, when a study showed it could eat and digest plastic, not just degrading it, as other bacteria have been shown to do.

Researchers at the Royal Netherlands Institute for Sea Research also identified the enzymes responsible for this ability, which could lead to the development of new biodegradation technologies.

Their study suggests that Rhodococcus rubber can break down about 1% of fed plastic per year into carbon dioxide and other non-toxic substances. “This is certainly not a solution to the problem of plastic soup in our oceans,” the researchers stressed in a statement. Experiments are mainly proof of principle, “one piece of the jigsaw”.

Meanwhile, at Northwestern University, researchers have identified a species with a diverse range of metabolic pathways that allow it to consume certain compounds in plastic, and turn them into biodegradable polymers.

A study published in February in Nature Chemical Biology showed that Comamonas testosteronei can degrade some compounds released from the decomposition of polyethylene terephthalate, widely used in disposable food containers and packaging materials.

More studies are needed on how the polymer produced by the bacteria can be used. “But these polymers can be used as precursors to plastics, so you can basically use plastics to make new plastics,” says Ludmila Aristild, associate professor of civil and environmental engineering at Northwestern’s McCormick School of Engineering and lead author of the study. .

Arctic explorers

We’ve known for some time that as global temperatures rise, melting Arctic permafrost releases alarming amounts of methane — a greenhouse gas 25% more potent than carbon dioxide — into the atmosphere. A study published in March 2020 has discovered a type of methane-oxidizing bacteria living in high Arctic soil that may be able to offset some of these emissions.

A study led by Purdue University researchers suggests that net greenhouse gas emissions from the Arctic may be much lower than previously estimated, due to the growth of a type of bacteria known as high-affinity methanotrophs, or HAMs.

On average, methanotrophic bacteria consume 25 to 130 million metric tons of methane per year, says a study published in the journal Nature in 2018, and have fascinated researchers for their natural ability to oxidize the powerful greenhouse gas and convert it into the green, sustainable fuel methanol.

For years, little was known about how complex reactions occur. Now, findings from Northwestern University, published in the journal Science in March 2022, shed light on the enzyme the bacteria use to catalyze the reaction.

Current industrial processes require extreme pressures and extreme temperatures above 1,300°C to catalyze the methane-to-methanol reaction. Methanotrophs perform the reaction at room temperature and for free, the study notes. Once the process is decoded, can people replicate it?

“Methane has a very strong bond, so it’s very remarkable that there’s an enzyme that can do this,” Amy Rosenzweig, professor of molecular biology at Northwestern and senior author of the paper, said in a statement.

An oil agent

The rod-shaped bacteria commonly found in soil have their appetite for hydrocarbons surprising scientists.

“Bacillus subtilis, which is a good bacteria that has been used as a probiotic to improve gut health, can produce enzymes that break down the complex hydrocarbons in oil into simpler compounds — tiny bubbles, essentially — making it easier for other microbes to feed on the oils,” bacteria- says Mukesh Dobal, an applied researcher and retired professor of biotechnology at the Indian Institute of Technology, Madras (IIT-M).

Bacillus subtilis can help purify impure oils; Break down industrial waste; Clean up oil spills as well. A study conducted at IIT-M, published in the journal Energy Sources Part A: Recovery, Utilization, and Environmental Effects in 2016, found that Bacillus subtilis was able to degrade crude oil samples by up to 80% within 10 days, the process. Usually a group of bacteria takes weeks or months.

“The beauty is that you don’t need to genetically modify this bacteria,” says Doble. To help it get started, it needs a little glucose as a nutrient source, then it will gradually adapt and seek out carbon sources of its own accord; In oil, this discovery leads it to break down hydrocarbons.”

One drawback is that it does not work well amid contamination by other microorganisms, including unwanted strains of Bacillus subtilis. Contamination control measures will be important for any eventual use of this bacterium in industrial processes. Another thing to watch for will be mutations over time, which can affect efficacy and performance, Doble says.

Carbon guzzler

The cleanest way to rapidly remove carbon dioxide from the air is to feed cyanobacteria, suggests a study published in 2022 in Renewable and Sustainable Energy Reviews. This bacteria acts quickly and does not produce toxic waste in the process. Instead, it converts carbon dioxide into oxygen and organic compounds that can be used to make biofuels and feedstock.

Another study published in Environmental Science and Technology in 2018 estimated that, globally, cyanobacteria and other phytoplankton have the potential to release 1.5 billion tons of carbon each year through photosynthesis in the oceans.

A challenge in using cyanobacteria for large-scale industrial application is the development of cost-effective and scalable cultivation techniques. Also, the researchers say, different strains differ in growth rates, biomass production and abilities to produce desired compounds, making consistent results a challenge.

Bacteria can’t perform miracles, but we’re at the point where every bit counts.

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