Traditionally, large-scale hydrogen (H2) is produced through
steam reforming of natural gas [1]. This process involves the conversion of methane and water into carbon dioxide (CO2) and molecular
hydrogen at high temperature. H2 can also be obtained through electrolysis of water and thermocatalytic reformation of other H2 containing organic compounds [2]. Both are polluting and expensive
processes [3]. Biological hydrogen (bioH2) can be produced mainly
by two routes: photobiologically and by fermentative processes
(photofermentation and dark fermentation) [4]. The first one is
based on the uptake of CO2 or other organic substrates and water
by photosynthetic organisms. Its major drawbacks are the requirement of a constant light source supply and the low yields of the overall process [5]. Dark fermentation consists in the conversion of
sugars into H2, CO2 and organic acids by microorganisms, through
the acidogenic pathway. Theoretically, any sugar-containing biomass can be used as a feedstock [6] and if the chosen biomass is readily available and lost-cost, the appeal of the process could be
increased.