Metabolic engineering of Saccharomyces cerevisiae for improved polyphosphate production

Phosphorus scarcity and legislative pressure for recycling demand novel methods to convert phosphorus-rich waste into useful products. Producing inorganic polyphosphate (polyP) via microbial synthesis offers an eco-friendly alternative to energy-intensive chemical methods while providing a valuable, recyclable phosphorus source for various applications.

Saccharomyces cerevisiae, a common yeast, naturally accumulates polyP as a phosphate store during periods of orthophosphate (Pi) deficiency, but the current multi-stage process hinders industrial feasibility.

Researchers investigated 57 engineered Saccharomyces cerevisiae CEN.PK113-7D strains to find metabolic tweaks that separate polyP production from Pi scarcity, eliminating the need for starvation. Constitutively activating the PHO regulon led to the most significant increase in polyP generation, while blocking inositol pyrophosphate synthesis, Pi absorption, or the vacuolar transporter chaperone complex disrupted accumulation.

This suggests that effective polyP production necessitates a balance between Pi uptake and vacuolar polymerization.

Notably, removing the PHO80 gene transformed a temporary starvation reaction into a permanent production trait, allowing significant polyP synthesis even during regular growth. Enhancing the growth medium further boosted polyP amounts, and electron microscopy confirmed higher vacuolar storage. In aerobic fed-batch cultivation, pho80Δ yeast simultaneously produced biomass and polyP, achieving 22.1% polyP content by dry weight and a concentration of 8.2 g/L—both expressed as KPO3 equivalents.

These results position Saccharomyces cerevisiae pho80Δ as a promising candidate for biological polyP production and phosphorus recovery.