Exploring factors, other than oxygen, that govern the use of terminal oxidases (BeyondO2)

Microorganisms harbor enzymes, so-called low and high-affinity terminal oxidases (TOs), which allow them to use O₂ across these concentration gradients for energy production. It is commonly assumed that the capacity to respire low O₂ concentrations is due to the presence of high-affinity TOs, while low-affinity TOs are used at high concentration of O₂. Yet there is growing evidence that the use of low- and high-affinity TOs does not follow this dogmatic pattern learned from our school textbooks, but that the regulation mechanisms are more complex.

We recently found that members of a ubiquitous soil bacterial group, the Acidobacteriota, can use their low-affinity TOs to respire low O₂ concentrations. This suggests that other factors – beyond O₂ – govern the expression of these TOs. We will expand upon this observation and explore other physiological and environmental factors that potentially could drive the use of these TOs, presumably giving the organism more metabolic flexibility to handle stressors. This will be achieved by using a multifaceted approach of genomics, gene expression analysis, respiratory kinetics and growth-based experiments of environmental relevant model soil microorganisms – select strains of the abundant Acidobacteriota and of other representative soil bacteria. This project will be a major contribution to understanding the drivers of the differential use of TOs and can have significant implications in our understanding of microbial physiology.

The project is led by Stephanie A. Eichorst, in collaboration with Dagmar Woekben, Anna Lopatina and Filipa Sousa (University of Vienna) and Emilio G. Garcia-Robledo (University of Cadiz, Spain). 

This project is funded by the Austrian Science Fund (FWF) FWF Grant-DOI 10.55776/PAT8860623.