Balance of the Groundwater Microbiome

Speaker: Kirsten Küsel (Friedrich Schiller University Jena)

Host: Andreas Peschel (CMFI)

Date & Time: 05.02.2026 | 12:30–15:00 p. m.

Venue:  Hörsaal 3M07, GUZ

Public Event. No registration needed and everyone welcome.

Abstract: 

Groundwater ecosystems represent a low-energy model within the Balance of the Microverse, offering a compelling contrast to high-energy, host-associated microbiomes such as the human gut. In these oligotrophic environments, microorganisms face chronic energy limitation, driving strong evolutionary pressure toward smaller, streamlined genomes, specialized metabolic strategies, and cooperative resource sharing. Many taxa—such as members of the Candidate Phyla Radiation (CPR)—live as episymbionts, relying on mutualistic interactions to complement missing biosynthetic pathways. This tight coupling of physiology and interaction defines the subtle balance sustaining life in the deep subsurface.

Drawing on long-term studies across different groundwater systems, I will show how microbial resilience and variability depend on hydrological connectivity: connected systems fluctuate more but recover faster, while isolated systems remain stable until pushed beyond their adaptive limits. Hydroclimatic extremes, including drought and altered recharge, reconfigure dissolved organic matter inputs and trigger functional shifts in microbial metabolism. Metagenomic analyses further reveal a diverse and largely novel groundwater virome, whose auxiliary metabolic genes suggest understated yet pervasive viral modulation of host metabolism.

Together, these findings depict the groundwater microbiome as a self-organized, low-energy system maintaining dynamic equilibrium under environmental variability. Our studies reveal how the subtle balance within low-energy groundwater microbiomes contributes to global CO₂ and CH₄ fluxes, exemplifying how Balance of the Microverse connects microbial interactions to the stability of Earth’s biogeochemical cycles.