Abstract
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•Process of microbial granule formation and microbial components of mature granules.•Important enzymes useful in the Hydrogen production have ben briefly discussed.•Granular Hydrogen productions by different type of granules have been tabulated.•Molecular engineering and other options for improving H2 production.
Microbes recycling nutrient and detoxifying ecosystems are capable to fulfil the future energy need by producing biohydrogen by due to the coupling of autotrophic and heterotrophic microbes. In granules microbes mutualy exchanging nutrients and electrons for hydrogen production. The consortial biohydrogen production depend upon constituent microbes, their interdependence, competition for resources, and other operating parameters while remediating a waste material in nature or bioreactor. The present review deals with development of granular algae-bacteria consortia, hydrogen yield in coculture, important enzymes and possible engineering for improved hydrogen production.