Our Recent Study in ES&T Unveils the Mystery of Nanaerobic Digestion

In a recent study published in ES&T, former researchers from our lab, including Duc Nguyen, Shilva Shrestha, and collaborators from the University of Michigan (Lut Raskin) and Imperial College London (Zhuoying Wu and Dr. Po-Heng Lee), have identified a new class of microorganisms, termed "nanaerobes," which are revolutionizing our understanding of methane production in both animal guts and engineered waste digesters.

Nanaerobes operate in environments with extremely low oxygen levels, less than 2 μM (micro-molars), which is about 1% of what's found in the atmosphere. Remarkably, they cease to exist in higher oxygen conditions. What makes them special is their use of the enzyme, cytochrome bd oxidase, enabling them to thrive in these low-oxygen environments. The team's research focused on re-examining existing data from cow rumen and various waste-to-energy digesters. The findings are quite intriguing: animal stomachs, which produce significant amounts of methane, have a microbial community similar to micro-oxygenated digesters rather than traditional anaerobic ones. This similarity suggests that even trace levels of oxygen can significantly impact digestion efficiency.

This discovery opens new doors to understanding methane emissions from ruminants like cows and suggests innovative strategies for enhancing methane production from biomass. The full study is accessible here.