Soil microorganisms in temperate soils are often faced with fluctuating conditions, for instance regarding the availability of carbon (and thus energy) and oxygen. Despite these challenges, certain groups of bacteria are particularly successful in soils. In our research, we investigate the genomic potential and physiologies of these soil bacteria to reveal the mechanisms that enable them to survive or even thrive in the often-challenging soil habitat.
One group that we focus on are the Acidobacteriota that are characterized by large phylogenetic diversity and great abundance in soils worldwide. In a comparative genomic investigation, we identified different physiological capacities that could provide them with an advantage in soil (Eichorst et al., 2018, Environmental Microbiology). We investigated these features in detail, and our research revealed that acidobacteria were able to use low-affinity terminal oxidases at nanomolar oxygen concentrations for respiration, in contrast to the established dogma that high-affinity oxidases are required at these concentrations (Trojan et al., 2021, mSystems). As low-oxygen habitats are widely distributed on Earth, these findings can have implications for other systems.
Furthermore, members of the Acidobacteriota have the capacity to oxidize atmospheric H2 during periods of starvation (Giguere & Eichorst, et al., 2021, The ISME Journal). This is a mechanism that can be used to generate energy for bacterial survival during periods of carbon limitation, which is a major advantage in the soil habitat. Thus, our studies uncovered great physiological flexibility of this abundant group of soil bacteria (Trojan et al., 2024, FEMS Microbiology Ecology), which can explain the success and thus ubiquity of these bacteria.
