Understanding Circadian Rhythms of Cellulases Could Improve Biofuel Production

Jennifer Hurley grew up in a strict household where sugar and sweets were forbidden.  

But what her parents didn’t know was Hurley and her grandfather had a secret stash of cheese Danishes hiding in the microwave in her grandfather’s kitchen. When she would stay overnight at his house, the duo would get up at 4:30 a.m. and eat pastries while everyone was asleep.

Hurley wasn’t an early riser just for the sake of consuming sugar. Waking early was just part of her routine.

By age 10, she started going to sleepovers and quickly learned that most kids weren’t getting up that early.

“It was odd to find that no one else got up as early as I did. I realized that this was a unique way to live your life and I thought I had a sleep disorder,” Hurley explained.

Her interest in understanding her sleep led her to pursue medical school. But she quickly realized medical school would not fulfill her curiosity about why she was like she was (and she really didn’t like needles!). Instead, she attended Rutgers University for graduate school, where she rotated in the lab of Isaac Edery, an expert in the molecular biology and biochemistry of the circadian clock.

“It was the first time I encountered someone doing circadian research, and it was amazing and exciting, and explained why I was like I was,” Hurley said.

That experience sent her down a career path of studying circadian rhythms—the 24-hour cycles that affect natural processes to help organisms cope with the regular shift from day to night. 

Hurley, a molecular biologist at Rensselaer Polytechnic Institute, is particularly interested in understanding how clock regulation over metabolism could help maximize cellulase production. Cellulase is an enzyme that helps break down lignocellulose−the binding that makes the woody part of plant cell walls rigid. When cellulase is extracted from fungi, it can be a significant resource for biofuels produced from lignocellulose.

She was awarded the Facilities Integrating Collaborations for User Science (FICUS) program funding last year, which allows her to use resources at the Environmental Molecular Sciences Laboratory (EMSL), the Joint Genome Institute (JGI), and Bio-SANS Beamline to identify the times of day that the filamentous fungus Neurospora crassa makes cellulase, which could help maximize the manufacturing of biofuel components. Listen to Hurley explain her research.

Circadian Rhythms and Fungi

Circadian rhythms affect every organism on the planet that lives in the photic zone, also known as the sunlight layer. This includes humans, plants, and microbes. For humans, physiology is so extensively timed by circadian rhythms that when it gets out of sync, health problems like cancer, diabetes, and heart disease can surface.

For fungi, understanding circadian rhythms could have a beneficial influence on the production of biofuels.

“Neurospora crassa is a great model system to work with because the circadian clock in this fungi is very similar to the circadian clocks in other organisms, including humans. So, understanding how circadian rhythms are timed in one fungus can help us learn a lot about other fungal systems, as well as human systems,” Hurley explained.

In this EMSL-JGI FICUS research, Hurley is working to identify the link between time of day and metabolic regulation to maximize the manufacturing of biofuel components.

“For researchers at the DOE who are actively studying how to make the most cellulases, knowing that there's a time of day to harvest the organism when you can maximize cellulase yield could be really important,” she said.

Hurley is using EMSL, JGI, and BioSANS capabilities in cryo-electron microscopy, nuclear magnetic resonance imaging, and protein production pipelines to map shifts in the circadian day and analyze the effect those shifts have on cellular physiology. With this data, Hurley and her research team will generate models of the circadian regulation of metabolism.

This research will contribute to understanding metabolic control of cellulases in key fungal species, plants, and bacteria, and will provide insight into clock regulation of metabolism for biofuel manufacturing.

“By studying the clock in Neurospora in the context of the production of cellulases, we can find simple methods, like changing the time of day of harvest, to exploit what we know about circadian rhythms to enhance the research goals of the Department of Energy,” Hurley said.