James BradleyScientist

Institut méditerranéen d'océanologie (MIO)1

SIESTA (Horizon Europe - ERC StG 101115755)
The Role of Microbial Dormancy as an Ecological and Biogeochemical Regulator on Earth

Dramatic shifts in Earth’s climate and geography have profoundly influenced biological innovation and biogeochemical cycles. Despite widespread and extreme environmental change including global glaciations lasting millions of years, microbial life has thrived: accruing distinct phylogenies, morphologies, physiologies, and functions over geological time. Microorganisms use dormancy as a survival strategy to persist throughout unfavorable changes in their environment. Dormant organisms withdraw from the present environment and become part of a seed-bank, investing instead in contributing to the diversity and function of future ecosystems. This leads to the rousing proposition that a shift in the active/dormant fraction of a microbial population may profoundly affect ecological functioning and elemental cycling. Despite this intriguing connection, we lack fundamental knowledge on the prevalence, triggers and timescales of dormancy, and how these factors affect ecosystems and elemental budgets. I will address this by elucidating the role of microbial dormancy as an ecological and biogeochemical regulator on Earth. The cryosphere provides a unique testing ground to meet my goals. Here, microbes contend with dramatic variations in environmental extremes on timescales ranging from days to thousands of years. Through an innovative data-driven approach involving experiments and modelling, I will:
1) quantify the prevalence of dormancy among taxonomically and functionally diverse microbial communities,
2) identify the triggers and timescales of dormancy,
3) link dormancy to the emergence, survival and evolution of microbial populations
and 4) elucidate the role of dormancy as a regulator of biogeochemical cycles.

Understanding the interplay between microbial dormancy, ecological processes and biogeochemical cycles holds the key to understanding the co-evolution of life and our planet, and how life excels throughout glacial-interglacial cycles and other global changes.

• 1Aix-Marseille Université/CNRS/IRD/Université de Toulon