The global transition toward carbon-neutral energy carriers has intensified interest in biohydrogen as an alternative to fossil fuels. Unlike conventional hydrogen production, biohydrogen generated through microbial or algal systems offers zero direct carbon emissions and can be produced from renewable biological resources.
Tetraselmis indica, a recently characterized halophilic microalga, presents a compelling candidate for integrated biohydrogen production. Its robust salt tolerance and metabolic flexibility enable cultivation in brackish or saline conditions, substantially reducing freshwater consumption compared to traditional freshwater algal species. This property is particularly valuable in water-scarce regions and coastal applications.
The microalga produces hydrogen through two primary photosynthetic mechanisms: direct photolysis, where light directly splits water molecules, and indirect photolysis, which involves more complex metabolic routes. Research has shown that operational parameters—notably light intensity and salinity stress—significantly influence hydrogen yield. The organism's [FeFe]-hydrogenase enzyme catalyzes the final hydrogen evolution step, though species-specific characterization remains incomplete relative to terrestrial algae.
A critical advantage of T. indica is its potential dual-function capability. Simultaneous nutrient removal from domestic wastewater and hydrogen production within single-stage reactors addresses two challenges concurrently: energy generation and water treatment. This integrated biorefinery approach could eliminate treatment costs while generating bioenergy.
However, substantial technical and economic barriers remain. Current literature treats hydrogen production and nutrient recovery as separate processes, limiting understanding of their simultaneous operation. Techno-economic assessments and life cycle analyses reveal that scalability hinges on improving bioreactor design and reducing operational costs.
Future advancement requires multi-omics analysis to fully characterize T. indica's metabolic pathways and genomic capabilities. Optimized reactor configurations that maximize concurrent hydrogen evolution and phycoremediation are essential. Industry deployment will depend on validating economic feasibility at commercial scales and standardizing cultivation protocols. Bridging these gaps positions T. indica as a viable component of future sustainable energy infrastructure.
