Processing recommendations for using low-solids digestate as nutrient solution for poly-ß-hydroxybutyrate production...

Area of Science:

• Biotechnology
• Environmental Science
• Microbiology

Background:

• Increasing plastic pollution necessitates biodegradable alternatives like poly-ß-hydroxybutyrate (PHB).
• Current PHB production using heterotrophic bacteria competes with food resources.
• Photoautotrophic cyanobacteria offer a sustainable alternative for PHB synthesis from CO2.

Purpose of the Study:

• To enhance the economic viability of PHB production using cyanobacteria.
• To investigate the use of nutrients from anaerobic digestate for cyanobacterial PHB synthesis.
• To evaluate the scalability of digestate-based PHB production.

Main Methods:

• Cultivation of Synechocystis salina in various digestate fractions and dilutions.
• Assessment of biomass and PHB production under different digestate conditions.
• Scale-up experiments in a 200 L photobioreactor.

Main Results:

• Optimal conditions involved precipitated and centrifuged digestate diluted 1/3, yielding high biomass and PHB concentrations.
• Scale-up in a photobioreactor achieved significant biomass and PHB yields, comparable to mineral media.
• Digestate utilization proved effective, though cultivation time was extended.

Conclusions:

• Anaerobic digestate is a viable, low-cost nutrient source for cyanobacterial PHB production.
• This approach reduces reliance on food crops and offers an alternative to digestate disposal.
• The study validates digestate as a sustainable feedstock for biodegradable polymer manufacturing.