These are capable of constantly producing hydrogen from organic compounds throughout the day and night.
For example, photo-fermentation with Rhodobacter sphaeroides SH2C can be employed to convert small molecular fatty acids into hydrogen.
E. aerogenes has a short doubling time and high hydrogen productivity and evolution rate.
A theoretical maximum of 4 mol H2/mol glucose can be produced by strict anaerobic bacteria.
Facultative anaerobic bacteria such as E. aerogenes have a theoretical maximum yield of 2 mol H2/mol glucose.