Simplified engineering design towards a competitive lipid-rich effluents valorization

Area of Science:

• Biotechnology and Bioengineering
• Microbial Production of Biopolymers
• Waste Valorization

Background:

• Food industry effluents contain fatty acids and glycerol suitable for producing valuable biopolymers: triacylglycerides (TAGs) and polyhydroxyalkanoates (PHAs).
• Conventional methods for TAG and PHA production involve multi-step processes, including substrate pretreatment and separate enrichment and accumulation phases.
• Simplifying these processes is crucial for efficient and cost-effective biobased chemical production.

Purpose of the Study:

• To develop a simplified, single-reactor process for simultaneous TAG and PHA production from industrial waste fish oil.
• To investigate the effect of a double growth limitation (DGL) strategy and pulsed feeding on biopolymer accumulation.
• To optimize reactor cycle configurations for enhanced biopolymer yield and production efficiency.

Main Methods:

• Coupling substrate hydrolysis, culture enrichment, and biopolymer accumulation (TAG and PHA) in a single sequencing batch reactor (SBR).
• Utilizing a double growth limitation (DGL) strategy with pulsed feeding of industrial waste fish oil during the feast phase.
• Testing different SBR cycle configurations (12h, 18h, and 24h cycles) to evaluate performance.

Main Results:

• Achieved up to 51 wt% biopolymers (TAG:PHA ratio of 50:51) with a yield of 0.423 Cmmol_BIOP/Cmmol_S after a 6-hour feast phase in 12-hour cycles.
• Observed over 25% higher daily storage compound production compared to separate enrichment and accumulation stages.
• Identified carbon influx during the feast phase and C/N ratio as key parameters controlling biopolymer production and culture selection.

Conclusions:

• A single SBR operated under DGL strategy effectively integrates substrate hydrolysis, enrichment, and simultaneous TAG and PHA accumulation.
• Optimized cycle configurations, particularly longer feast and famine phases, enhance biopolymer storage capacity.
• The study demonstrates a simplified and more efficient approach for producing valuable biopolymers from waste streams.