Newly found bacteria fights climate change, soil pollutants

Cornell researchers have discovered a new species of soil bacterium - named after the Cornell professor who first discovered it - that is particularly adept at breaking down organic matter, including cancer-causing chemicals that are released when coal, gas, oil and waste are burned.

"Microbes have been around since the beginning of life, almost 4 billion years ago. They created the system we live in, and they maintain it," said Dan Buckley, professor of microbial ecology in the Soil and Crop Science Section of the School of Integrative Plant Science. "We may not see them, but they're the ones calling the shots."

Buckley and five other Cornell researchers, along with colleagues at Lycoming College, described the new bacterium in a paper, "Paraburkholderia madseniana sp. nov., a phenolic acid-degrading bacterium isolated from acidic forest soil," published February 6 in the International Journal of Systematic and Evolutionary Microbiology.

The new bacterium, madseniana, is named after the late Gene Madsen, the microbiology professor who initiated the research. He died in 2017, before he could confirm the discovery.

All plants and animals, including humans, harbor a collection of friendly bacteria that help us digest food and fight infections. Bacteria that live in soils not only help plants grow, cope with stress and fight pests, they are also essential to understanding climate change.

Recently discovered bacteria belong to the genus Paraburkholderia, which are known for their ability to degrade aromatic compounds and, in some species, for their ability to form root nodules that fix atmospheric nitrogen. The name of the species, madseniana, reflects the legacy of Madsen's work in environmental microbiology.

Madsen's research focused on biodegradation - the role that microbes play in the breakdown of pollutants in contaminated soils - with a particular focus on organic pollutants called polycyclic aromatic hydrocarbons (PAHs). His work has been groundbreaking in providing natural tools for treating hazardous waste in areas where contaminated soils cannot be easily dug up and removed.

"Gene was a humble man and a great scientist. I am so happy to see his legacy continue in this way," said Esther Angert, Professor and Chair of the Department of Microbiology. "It is so fitting that a bacterium with these characteristics should bear the name of this remarkable environmental microbiologist. I think Gene must be smiling".

The work began in a Cornell experimental forest on Turkey Hill, a natural area managed by the Cornell Botanical Garden. Madsen isolated the new bacteria from the forest floor; Buckley's team completed the project.

The first step was to sequence the bacterium's ribosomal RNA genes, which provided genetic evidence that madseniana was a unique species. In studying the new bacterium, the researchers found that madseniana is particularly adept at breaking down aromatic hydrocarbons, which make up lignin, a major component of plant biomass and soil organic matter. Aromatic hydrocarbons are also present in toxic PAH pollution.

This means that the newly identified bacteria could be a candidate for biodegradation research and an important player in the soil carbon cycle.

Dr. Buckley's lab focused on the role of the bacterium in the carbon cycle - the natural carbon cycle through the earth and atmosphere, which scientists believe has been disrupted by excessive human carbon emissions.

"We know remarkably little about how soil bacteria function," Buckley said. "Soils each year process about seven times more carbon than all human emissions from cars, power plants and heaters around the world just in their natural work of breaking down plant matter. As a large amount of carbon passes through the soil, small changes in the way we manage soils could have a significant impact on climate change.

In the case of madseniana, Dr. Buckley's lab wants to learn more about the symbiotic relationship between the bacterium and forest trees. Early research suggests that trees provide carbon to the bacteria, which in turn degrade soil organic matter, releasing nutrients such as nitrogen and phosphorus to the trees.

Understanding how bacteria degrade carbon in the soil could be the key to soil sustainability and the ability to predict the future of the global climate.

Roland Wilhelm, a postdoctoral associate in Buckley's lab, was the first author of the paper. Other co-authors include Sean Murphy, a PhD student in the lab, Nicole Feriancek (22) and David Karasz (20), undergraduate research assistants, Christopher DeRito, research support specialist, and Jeffrey Newman, professor of biology at Lycoming College.