„Hydro-” od wodoru (hydrogen).
Wystarczy poguglać angielskie artykuły na temat firmy AirProtein:

The hydrogenotrophs – “nature’s supercharged carbon recyclers” – feed on CO2 and convert it into food with the help of hydrogen from water, synthesising the gas into cellular material.
Źródło: https://www.proportionfoods.com.au/conjuring-protein-from-th...

W niektórych artykułach też są nazywane bardziej przyjaźnie „hydrogenotrophic microbes”:
Air Protein cultivates hydrogenotrophic microbes inside fermentation tanks and feeds them a mix of carbon dioxide, oxygen, minerals, water, and nitrogen.
Źródło: https://www.wired.co.uk/article/air-protein-co2-food

I Wikipedia:
Hydrogenotrophs are organisms that are able to metabolize molecular hydrogen as a source of energy.
Źródło: https://en.wikipedia.org/wiki/Hydrogenotroph