An anaerobic native approach to shine Light on C1-cycling biochemistry using Environmental microbial biomass.

Microorganisms have shaped the Earth's biogeochemistry for almost 4 billion years.

Among them, anaerobic archaea dominate the carbon one-unit cycle, nourish ecosystems, and orchestrate the final step of organic matter degradation.

They remain mainly uncharacterised and uncultured while harbouring a universe of concealed enzymatic chemistry, which cannot be approached via classic omics.

EnLightEn will study these non-isolated archaea as part of the ""microbial dark matter"" by exploiting native biomass rather than artificial systems.

The overall carbon-processing catabolic landscape will be pictured through an anaerobic pipeline, simultaneously investigating multiple enzymes bound to physiological partners and equipped with native (metallo)cofactors.

This approach proved its success by deciphering the first and last steps of the ethane-oxidation process from an anaerobic microbial enrichment breaking the accepted metabolic model of archaeal alkanotrophy.EnLightEn will develop into three branches. (i) We will pioneer the biochemical investigations of enzymes from methanotrophic archaea enrichments. (ii) The native catabolic machinery from acetate-degrading methanogens, the prime methane producers in the world, will be isolated from mesocosms. (iii) As the most challenging project, we will study marine environmental enzymes from sediments and microbial mats conducting anaerobic methanotrophy and methanogenesis.

Catabolic enzymes are naturally in high abundance in these multiple subspecies communities.

Single protein populations will be sorted out by chromatography and ultimately by crystallisation and studied by a suite of biophysical, biochemical and structural technics, as we recently did for a methane-generating enzyme isolated from a wastewater treatment plant.EnLightEn will open a field to characterise the functional dark matter, which can be further applied to other metabolisms and offer an unprecedented view of the molecular tricks used by the microbial world.