The Green Review

Universities play a crucial role in achieving a sustainable future, especially through their research. Considering this, we are excited to highlight individuals and groups at UNB that have dedicated their time to pursuing sustainability-related research.

Our newest Sustainability Research Champion is Louise Sennett

Research project

(STARVOX) Revealing effects of starvation and oxidative stress on denitrifying bacteria: a basis for novel N2O mitigation and industrial applications.

Overview of your research

Nitrous oxide (N2O) is a potent greenhouse gas and a major contributor to ozone depletion, with a global warming potential 300 times greater than carbon dioxide (CO2). Agriculture is the leading source of anthropogenic emissions, driven by its dependence on nitrogen (N) fertilizers that are consequently converted to N2O through soil microbial processes of nitrification and denitrification.

Denitrification is an anaerobic respiration process that requires carbon and low oxygen to convert N2O to harmless atmospheric dinitrogen gas (N2). Bioengineering the soil denitrifying community has been brought forth as a potential strategy to reduce N2O emissions. Achieving this, however, requires an improved understanding of how denitrifying organisms manage N2O under stressful conditions. For example, in both natural and engineered systems, microorganisms often face fluctuations in carbon and oxygen availability, resulting in periods of carbon starvation and oxidative stress that may impair the ability of denitrifiers to convert N₂O to N₂.

STARVOX is placed at the interface between microbial ecology/physiology and industrial microbiology. The project will provide fundamental understanding of the regulatory biology of denitrifying bacteria when stressed by starvation and fluctuating oxygen. This is relevant for understanding the ecophysiology of bacteria in nature and strengthens ongoing projects on engineering of agricultural systems to mitigate emissions of N2O and projects developing novel single-cell production based on anaerobic respiration.

The STARVOX project is funded by the Research Council of Norway (FRIPRO project no. 325770) and is hosted at the Norwegian University of Life Sciences (NMBU) in Ås, Norway, under the principal investigation of Prof. Åsa Frostegård.

Since August 2022, I have worked as a postdoctoral researcher on the project, leading investigations into the influence of carbon starvation and oxidative stress on denitrification and N2O emissions in complex soil bacterial communities. I combine detailed gas kinetic analyses (using our unique robotic incubation system) and multi-omic approaches (metagenomics, metatranscriptomics, and metaproteomics) to understand ‘who is there?’ and ‘what are they doing?’ in response to fluctuating soil conditions.

How does your work intersect with sustainability?

STARVOX will unravel mechanisms controlling N2O emissions under environmentally relevant conditions, thus providing a more realistic and improved understanding compared to previous research. These insights will strengthen efforts to predict and mitigate N2O emissions, directly contributing to the UN Sustainable Development Goal 13 on Climate Action and reflecting the global commitment made at COP1 in Paris to limit global temperature rise.

What impact do you hope this research will have?

We hope that this research will provide new insights into how denitrifying organisms respond to carbon starvation and oxidative stress, conditions common in natural and engineered systems, thus substantially advancing our understanding of denitrifier ecophysiology in general and their role in anthropogenic N2O emissions.

The NMBU Nitrogen and Microbial Ecology and Physiology (MEP) groups have been leaders in denitrification and N2O emission research for over 20 years. This foundational work led to the discovery of a novel N2O-reducing bacterium capable of decreasing soil N2O emissions by up to 95%. We anticipate that the insights gained from the STARVOX project will be critical in advancing the development of such mitigation tools by informing bioengineering approaches that harness denitrifying bacteria resilience to environmental stresses like carbon starvation and oxidative stress.

Learn more

Connect with me and explore my work on LinkedIn.

STARVOX project | NMBU MEP group | NMBU Nitrogen Group

Discover Dr. Elisabeth Hiis’ research on N2O-reducing bacteria: Hiis, E.G., Vick, S.H.W., Molstad, L. et al. Unlocking bacterial potential to reduce farmland N2O emissions. Nature 630, 421–428 (2024).

Know someone who should be a Sustainability Research Champion? Let us know at sustain@unb.ca.