Contributions to a circular phosphate economy – Polyphosphate production in Saccharomyces cerevisiae
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Beschreibung
Phosphate (Pi) is an essential but limited resource, typically obtained through mining of Pi rock. This thesis advances the biotechnological production of high-value polyphosphate (polyP) using Saccharomyces cerevisiae as a sustainable approach for Pi recycling. By optimizing screening methods, identifying promising yeast strains, and improving production conditions, this work supports the implementation of industrial bio-polyP production and the transition toward a circular Pi economy.
Phosphate (Pi) is an essential nutrient for all living organisms and plays a crucial role in modern agriculture. Most of the Pi used by humans is derived from mined Pi rock and processed into agricultural fertilizers. However, the currently established linear Pi economy faces challenges such as geopolitical dependence on limited reserves, rising fertilizer prices, heavy metal contamination, and ecological damage caused by extensive Pi application. These challenges are expected to intensify due to population growth and increasing meat consumption. Sustainable Pi management therefore requires a transition toward a circular Pi economy.
This thesis contributes to this transition by advancing biotechnological polyphosphate (polyP) production using Saccharomyces cerevisiae (S. cerevisiae). The previously established polyP hyperaccumulation protocol was adapted for high-throughput screening and combined with the JC-D7 fluorescence assay to analyze yeast strains for altered polyP content, chain length, and growth performance. The JC-D7 assay demonstrated high robustness against various abiotic factors and extraction conditions, enabling rapid classification of yeast strains based on their polyP production levels. Furthermore, systematic evaluation of trace elements and vitamins during the starvation phase revealed zinc and inositol as key factors enhancing polyP accumulation in S. cerevisiae. Zinc stimulates the Pi-responsive signaling pathway during Pi starvation. The role of inositol was examined using phospholipid mutants and strains carrying deletions of genes involved in inositol synthesis or transport. In this context, the minimal medium requirements for both the starvation and feeding phases of the polyP hyperaccumulation process were redefined. Collectively, these findings contribute to reduced nutrient consumption, improved product purification efficiency, and a deeper understanding of polyP metabolism in S. cerevisiae.
The results of this dissertation, combined with process-guided strain engineering, provide an opportunity to promote the industrial implementation of biotechnological polyP production with S. cerevisiae and contribute to the transition toward a circular Pi economy. To fully realize its potential, informed decisions regarding raw materials, strain development, product applications, and process design, supported by collaboration between research, industry, policy, and society, are essential.
Autor*in
Alexander Deitert
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Naturwissenschaften Mikrobiologie Applied Microbiology