The relationship between photosystem II regulation and light-dependent hydrogen production by microalgae

Certain microalgae species are capable of light-dependent hydrogen production under conditions of dark anaerobic incubation or nutrient deprivation. From the biotechnological point of view, this phenomenon is a process of synthesizing the energy carrier H₂ while consuming light energy. Here, we overview the functional connection between the photosynthetic machinery and light-dependent hydrogen production and assess the physiological significance of this process. We characterize events involved in PSII downregulation, as well as the relationship between PSII regulation mechanisms and hydrogen generation. We suggest that the light-dependent hydrogen production forms part and parcel of the sophisticated regulatory network ensuring adaptation of microalgae to such environmental stresses as anaerobiosis or nutrient deprivation.