Engineering microalgae for water phosphorus recovery to close the phosphorus cycle

As a finite and non-renewable resource, phosphorus (P) is essential to all life and crucial for crop growth and food production. The boosted agricultural use and associated loss of P to the aquatic environment are increasing environmental pollution, harming ecosystems, and threatening future global food security. Thus, recovering and reusing P from water bodies is urgently needed to close the P cycle. As a natural, eco-friendly, and sustainable reclamation strategy, microalgae-based biological P recovery is considered a promising solution. However, the low P-accumulation capacity and P-removal efficiency of algal bioreactors restrict its application. Herein, it is demonstrated that manipulating genes involved in cellular P accumulation and signalling could triple the Chlamydomonas P-storage capacity to similar to 7% of dry biomass, which is the highest P concentration in plants to date. Furthermore, the engineered algae could recover P from wastewater almost three times faster than the unengineered one, which could be directly used as a P fertilizer. Thus, engineering genes involved in cellular P accumulation and signalling in microalgae could be a promising strategy to enhance P uptake and accumulation, which have the potential to accelerate the application of algae for P recovery from the water body and closing the P cycle.

Automated summary

As a finite and non-renewable resource, phosphorus is crucial for crop growth and food production. However, agricultural use and associated loss of phosphorus to the aquatic environment are causing environmental pollution and threatening global food security. Microalgae-based biological phosphorus recovery is considered a promising solution, but the low accumulation capacity of algae restricts its application. By manipulating genes involved in cellular phosphorus accumulation and signaling, researchers have tripled the phosphorus storage capacity of algae and significantly improved its phosphorus recovery efficiency from wastewater. This genetic engineering approach has the potential to enhance phosphorus uptake and accumulation in microalgae, and accelerate the application of algae for phosphorus recovery and closing the phosphorus cycle.