A scientist building microscopic cleanup crews for chemicals

Hundreds of thousands of chemicals are produced and used in modern society, from antibiotics to pesticides and industrial compounds. They support many aspects of daily life. Yet after use, many of them eventually enter the environment, where their long-term fate and impacts remain difficult to predict. 

I am trying to understand how human-made chemicals perturb ecosystems, and how understanding their environmental fate can help reduce their impacts. For many compounds, we still know relatively little about how microorganisms interact with them, what products are formed, and what risks those products may pose.

I am a curious and question-driven scientist with broad research interests spanning environmental chemistry, microbiology, enzymology, and food science. My current work focuses on chemicals that are closely connected to water quality, agriculture, and environmental health, including pesticides, pharmaceuticals, plastic additives, and per- and polyfluoroalkyl substances (PFAS), often referred to as “forever chemicals.”

These chemicals are highly diverse in their structures, environmental behaviors, and biological reactivities. Such complexity makes it difficult to find a one-size-fits-all strategy for contaminant bioremediation. Effective cleanup often requires matching the right microbes or biological processes to the right contaminants and environmental conditions. Building the fundamental understanding needed for this kind of precision bioaugmentation is one of the central goals of my research.

One project I started at Stanford examines pesticide use in California over the past several decades. Together with my PhD student, we have been analyzing which chemicals were applied, how much was used, and where these applications occurred. From there, we are asking whether some of these pesticides can be transformed by microbes in the environment, whether those transformations produce products that are more or less persistent, and how those products affect ecosystem function and water quality, and how this knowledge can help us develop better strategies for monitoring, remediation, and risk mitigation.

To begin answering these questions, we selected more than 100 pesticides and are currently conducting laboratory experiments with soil and water samples to study how they are transformed or degraded in the environment. 

In parallel, we are working to identify and cultivate the microorganisms responsible for these transformations, with the goal of developing more targeted biological solutions for contaminant remediation. In the long term, I hope the knowledge we generate can also help guide the design of safer and more sustainable chemicals.

I deeply appreciate being at a place that values vision and is willing to invest in it. Some of the most important discoveries require patience. They may take years of fundamental research before practical solutions emerge. Stanford gives those ideas the opportunity to grow into real-world impact.

– As told to Katie Clary

Related: Yaochun Yu, assistant professor of civil and environmental engineering