Boosting Cyanobacteria Growth by Fivefold with Aggregation-Induced Emission Luminogens: Toward the Development of a Biofactory

Light utilization is the vital first step of photosynthesis for photoautotrophic organisms. Boosting the growth and yield of photosynthetic organisms is critical in sustainable food and biofuel production in a photobioreactor. In this contribution, we improved the light quality of cyanobacteria by the addition of aggregation-induced emission luminogens (AIEgens), which could absorb the ultraviolet/blue light and emit the green/yellow light into the culture medium, thus effectively converted the light to a more usable range. Our designed AIEgens formed highly bright luminogenic aggregates in the exposure medium and dispersed around the cells, which effectively modified the wavelength and spatial distribution of the light source. The photosynthesis parameters of AIEgen-treated cyanobacteria, including the maximum photosynthetic quantum yield, the effective photochemical quantum yield of photosystem II, and the relative electron transport rate, were significantly improved with the application of our AIEgens. Specifically, after 14 days of incubation, we demonstrated that the AIEgens boosted the cell density of cyanobacteria by 5-fold and the lipid contents by 5- to 6-fold. Furthermore, cyanobacteria continued to grow under UV light irradiation in the presence of AIEgens, highlighting the important role of AIEgens in light conversion to improve light quality. Our study demonstrated the potential application of AIEgens in a photosynthetic biofactory without genetic modification of photosynthetic organisms.