Small but mighty: can microbes save the planet?

Invisible to the naked eye, microbes are the most ancient and diverse life forms on Earth. Bacteria, viruses, fungi and algae have evolved over billions of years, developing an array of characteristics and functions crucial to the cycle of life. Through breakthroughs like the smallpox vaccine and penicillin, they have helped revolutionise medicine and save countless lives.

In recent years, advancements in microbiology have expanded the applications of microbes even further, including improving crop yields, combatting climate change and recycling. 

Microbes play a major role in global biological cycles, particularly in the circulation and distribution of carbon and other greenhouse gases. On one hand, they can be a source of emissions. During decomposition, bacteria break down organic matter through respiration, releasing carbon as a by-product. Algae grow rapidly in polluted waters, creating "dead zones" by depleting oxygen levels and making the environment inhospitable for other organisms.

But at the same time, microbial organisms can lock planet-warming gases away. Microbes in soil sequester carbon released during the decomposition of organic matter; consequently, the world’s soil contains two to three times more carbon than the atmosphere. That process has come under threat from industrial farming. Agricultural activities like ploughing and tilling disturb sequestration and release carbon back into the atmosphere. As farming has intensified over the past century, soil has sequestered 30-60% less carbon. Microbes can help reverse this. 

Scientists at Loam Bio, a microbial biotechnology company, have identified a specific class of fungal microbes that have the potential to improve soil sequestration properties. Fungi form extensive underground connections (mycelial networks) with plant roots, and have been doing so for over 400 million years. These enable them to interact with large volumes of soil across the root network. “We selected fungi because of their symbiotic relationships with plants, their ability to improve soil structure, and their resilience under diverse environmental conditions,” says Dr Robbie Oppenheimer, Chief Product Officer at Loam Bio. 

Loam Bio uses these fungal micro organisms to develop its seed treatment products, which are designed to help plants sequester carbon dioxide. Once added to the soil, they establish symbiotic relationships with plant roots to improve sequestration, nutrient retention, and farm productivity.

“We do extensive testing, including rigorous laboratory experiments and field trials, to ensure that our product improves agronomic outcomes for farmers,” says Dr Oppenheimer.

“Our research has led to new insights into the potential of soil microbes to improve soil health and act as a significant sink of stable soil carbon, suggesting that microbial solutions will complement other climate mitigation strategies.”

Tackling plastic waste

Indeed, microbes offer a host of other environmental benefits. They can enhance soil fertility, reducing the need for synthetic fertilisers, fungicides and insecticides and bolstering crop resilience in the face of environmental stressors. Certain microbial species can contribute to bioremediation – the removal of pollutants, toxins and other contaminants from soil and water. Microbes also play an important role in dealing with food waste through composting: bacteria break down food and biodegradable debris into nutrient-rich soil, simultaneously reducing waste and producing something useful. Scientists are looking to apply this principle to one of the most prevalent pollutants – plastic.

Plastic is a scourge on the environment because it does not biodegrade. It breaks into smaller and smaller pieces because of sunlight, oxidation or friction. But these microplastics – and eventually nanoplastics – stay in the environment, contaminating water and soil and harming animals. Scientists are developing new microbiological processes that aim to address this problem.

Plastics are comosed of polymers, long chains of repeating molecular units called monomers. Dr Joanna Sadler and colleagues at the University of Edinburgh recognised that these polymers, once broken down, could be transformed into higher-value products with the help of genetically engineered bacteria.

“Our goal is to both future-proof the plastics industry and address the more difficult aspects of current plastic waste,” says Dr Sadler. Their innovative approach involves feeding the carbon from plastic into a cell's metabolic processes. By manipulating the cell's genome, they can redirect this carbon to produce entirely different substances. So far, they have successfully converted PET plastic molecules into vanillin, the molecule responsible for the scent and flavour of vanilla and used in fragrance manufacturing.

“This approach allows us to view plastic as a potential feedstock for the green economy, which is a paradigm shift in how we think about plastic waste,” says Dr Sadler. “We’ve already proven it can be used to make vanillin, and there’s evidence from research around the world that plastic can be transformed into a range of interesting and commercially-relevant products. It’s a synergistic benefit.”

Further uses for bacteria can be discovered through genetic engineering, which can range from minor adjustments to extensive ones. Dr Sadler notes that incremental changes often yield better results. “It comes down to what you’re asking of the bacteria; if the edits are only a couple of steps from the starting material, it tends to be straightforward,” she says. “But if you’re introducing large synthetic gene clusters, this can compromise the viability and growth rate of the bacteria.” 

These advances in biotechnology not only showcase the remarkable adaptability of microbial life but also highlight the potential for nature-inspired solutions to address the pressing challenge of environmental degradation.