Hydrogenotrophic metabolisms in the subsurface: ecological and biotechnological applications.

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

Congreso; XVI FISV Congress; 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 one of the key technologies for 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 development could enable the urgent energy transition.When hydrogen is artificially stored in the subsurface, the extensive microbial ecosystem present insitu interacts with it, converting the H2 to H2S, FeS and other metabolic byproducts that cancompromise the viability of storage potentially reducing the production capacity of the storage site. In order to safely store hydrogen underground it is thus necessary to investigate the diversity anddistribution of natural hydrogenotrophic metabolisms in the subsurface. Given the high cost of drilling boreholes and/or accessing deep mines, one solution to characterize microbial communities in the subsurface is to use deeply-sourced seeps and hot springs, which carry fluids and gases from depth to the surface and generate hot spots of microbial diversity.The key enzymes controlling hydrogen utilization in microorganisms are called Hydrogenases, andare found in all domains of life, catalyzing the oxidation of molecular hydrogen to protons andelectrons. 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. Thiswork uses metagenomic approaches to investigate the diversity of Hydrogenases in samples fromdeeply-sourced seeps. Our results will help to establish the baseline of hydrogenotrophic metabolisms in the subsurface, aiding in the development of subterranean hydrogen storage technology.