Hydrogenotrophic metabolisms in the subsurface: ecological and biotechnological applications.

CASCONE M; BASTIANONI A.; SCELCI M.; CORDONE A; DI LORIO L; CORREGGIA M; BARRY P.; LLOYD K.; JESSEN G.; AGOSTINA CHIODI; DE MOOR M.; NAKAGAWA M.; RAMÍREZ C; SCHRENK M; IACONO R; MORACCI M; GIOVANELLI D.

Congreso; Cortona Procarioti microbiology meeting; 2022

Hydrogen is a fundamental electron donor in diverse microbial metabolisms and it is considered the energetic currency exchanged within microbial communities in anaerobic environments. Hydrogen is also considered one of the keys to a greener energetic society. Excess energy produced from renewable sources can be converted into hydrogen for storage and subsequent use. An important technology which is under development involves subsurface storage of hydrogen (known as underground hydrogen storage, UHS) in a stable terrestrial reservoir for later use. If viable, UHS developments could enable this imminent energy transition. However, when hydrogen is artificially stored in the subsurface, the extensive microbial ecosystem can interact with it, potentially reducing the production capacity of the storage site or converting the H to H2S, FeS and other metabolic byproducts that can compromise the viability of storage. In order to safely store hydrogen underground it is thus necessary to investigate the diversity and distribution ofnatural hydrogenotrophic metabolisms in the subsurface. Given the high cost of drilling boreholesand/or accessing deep mines, one solution to characterize microbial communities in the subsurface to use deeply-sourced seeps and hot springs, which carry fluids and gases from depth to the surfaceand generate hot spots of microbial diversity. The key enzymes controlling hydrogen utilization in microorganisms are called Hydrogenases, and are found in all domains of life, catalyzing the oxidation of molecular hydrogen to protons and electrons. These diverse enzymes use tangled organometal complexes built around a binuclearNi-Fe, Fe-Fe or Fe center, with bound CO and CN(-) groups, as well as multiple FeS centers. This work uses metagenomic approaches to investigate the diversity of Hydrogenases in samples fromdeeply-sourced seeps and hot springs. Our results will help to establish the baseline of hydrogenotrophic metabolisms in the subsurface, aiding in the development of subterranean hydrogen storage technology.