Understanding a Toxic Necessity

Jannell Bazurto, assistant professor of Plant and Microbial Biology at the University of Minnesota, is pursuing a better understanding of formaldehyde, a chemical that is carcinogenic, toxic, and produced by all living things.

By Reed Grumann

If you dissected a pig in high school biology, you might remember a sharp, acrid smell permeating the classroom and the teacher’s warning about a carcinogenic chemical called formaldehyde. Though often labeled a killer chemical, every organism on Earth, including humans, produces small amounts of formaldehyde. In very small quantities, it’s manageable. Produce or consume too much, and formaldehyde will kill otherwise healthy cells by attacking critical proteins and DNA.

While most organisms can neutralize small amounts of formaldehyde, researchers are just beginning to understand the mechanisms involved in formaldehyde regulation. Jannell Bazurto, a member of the BioTechnology Institute and an assistant professor of Plant and Microbial Biology, looks for clues in Methylobacterium, a type of bacteria that produces and neutralizes formaldehyde levels that would kill most other microbes.

As their name implies, methylobacteria have a unique ability to metabolize or breakdown, single-carbon molecules like methane and methanol. The process helps the cell maintain enough energy to survive, but also generates formaldehyde as an intermediate step. Fortunately, the bacteria are also uniquely equipped to handle sudden changes in concentrations of the toxin.

A key mechanism of Methylobacterium is an enzyme that converts formaldehyde into less harmful chemicals. While the enzyme is sufficient at normal levels of formaldehyde concentration, it’s not enough to handle exceptionally higher formaldehyde levels. To identify the function of two additional proteins suspected of playing a role in regulating formaldehyde levels, a group of researchers at the University of Idaho removed them from bacterial cells. And just like a cake without sugar and eggs, something was off. “If you don’t have [the two proteins] … you can see [the cells] accidentally overproduce formaldehyde, and they end up secreting it in the growth medium,” says Bazurto.

It’s still unclear exactly how these two proteins keep formaldehyde levels low in methylobacterium, but they aren’t alone in their efforts. Dozens of genes express proteins as formaldehyde levels change—a strong indicator of their importance in regulating the toxin. The challenge for Bazurto is knowing which of these genes, and the proteins they encode, actually play a role in formaldehyde metabolism. By manipulating each gene and looking at the results, Bazurto hopes to crack the code and establish which genes impact formaldehyde metabolism and their role in the process.

Once understood, these metabolic pathways could be hardwired into other microbes (like E. coli) through genetic engineering. Modified E. coli could consume methanol, neutralize formaldehyde, or produce marketable chemicals like biofuels and organic acids. In some facilities, formaldehyde is produced in large quantities as a building block for other chemicals. Wastewater remediation at these facilities would greatly benefit from bacteria genetically modified to directly consume formaldehyde and withstand toxic concentrations.

Throughout its industrial lifecycle, formaldehyde has the potential to creep into our air and water, putting humans at risk of exposure. The relationship between excessive formaldehyde exposure and human health issues—cancer, respiratory issues, and skin irritation—has been well established, yet we still know very little about how humans (and other organisms) sense and handle exposure to formaldehyde. As the search for practical applications in biotechnology, medicine, and environmental remediation continues, Bazurto remains fascinated by the basic science and “scenario where we actually know how to resolve formaldehyde toxicity itself.”

Reed Grumann is a writing intern in the Science Communication Lab, majoring in microbiology and political science. He can be reached at gruma017@umn.edu.

Image courtesy of Janelle Buzurto. Timecourse of Methylobacterium chemotaxing toward a capillary tube that has a formaldehyde plug in it. (Zero and five minutes). Cells seen faintly in the background at zero minutes begin to move toward the plug by the five minute point, forming a halo around the end of the tube.