ABSTRACT
Environmental pollution due to the use of fossil fuels as well as their shortfall makes it necessary to find alternative energy sources that are environmentally friendly and renewable. Hydrogen satisfies the requirements because when it burns, it produces only water. There are various processes for biohydrogen production: dark fermentation, photo-fermentation, biophotolysis, and hybrid fermentation. Biohydrogen can be produced by different raw materials such as glucose, sugarcane molasses, and starchy materials. Hydrogen production through dark fermentation has many advantages in comparison to other biological hydrogen production methods because of its ability to produce hydrogen from renewable resources such as carbohydrate-rich wastes, with the minimum external input of energy. Biohydrogen is produced by the fermentation of glucose under anaerobic condition. Hydrogenase is the principal enzyme that catalyzes the conversion of protons to hydrogen.
