ABSTRACT
Hydrogen is the most abundant element in the universe and holds great potential for use as an energy source in the future due to its high conversion efficiency recyclability and nonpolluting nature. A number of microorganisms have been identified that are capable of hydrogen production through their metabolic pathways by utilization of specific substrates. For production of hydrogen through the fermentation process, numerous reactors and fermenters have been designed with optimization of the process parameters including type of inoculum used, initial pH in batch-type fermenters, temperature, and metal ion concentration. Other advancements in the optimization of the process include use of mixed consortia, metabolic engineering of the pathways to increase hydrogen production, and use of reverse micelles for entrapment of the cells in them, which in turn offer better distribution of substrates and products in organic and aqueous phase, among other. Still, there is a long way to go to enhance the process efficiency for fermentative hydrogen production.
