Bio-based conversion of volatile fatty acids from waste streams to polyhydroxyalkanoates using mixed microbial...

Area of Science:

• Biorefinery and sustainable materials science.
• Microbial biotechnology and biopolymer production.

Background:

• Polyhydroxyalkanoates (PHAs) offer a biodegradable alternative to conventional plastics but face commercialization challenges due to high production costs.
• Optimizing PHA production processes is crucial for their widespread adoption in a circular economy.

Purpose of the Study:

• To develop and evaluate a cost-effective process for PHA accumulation using waste-derived volatile fatty acids (VFAs).
• To investigate the influence of different carbon sources on microbial community structure and PHA accumulation capacity.

Main Methods:

• Utilized mixed microbial cultures to accumulate PHAs from VFA-rich effluents from waste streams.
• Operated the bioprocess without strict pH or temperature control to simplify operations.
• Analyzed microbial community composition and PHA accumulation efficiency using different substrates.

Main Results:

• Mixed cultures effectively consumed VFAs from waste effluents, demonstrating adaptability to diverse substrates.
• Achieved a maximum PHA content of 43.5% (w/w), comparable to results obtained with synthetic carbon sources.
• The dominant bacterial phyla identified were Proteobacteria, Bacteroidetes, and Firmicutes.
• The resulting biopolymer was primarily composed of (R)-3-hydroxybutyrate (94.8%) with a smaller fraction of (R)-3-hydroxyvalerate (5.2%).

Conclusions:

• The proposed process demonstrates a viable strategy for reducing PHA production costs by utilizing low-cost, waste-derived feedstocks.
• The use of unmanaged conditions (no pH/temperature control) highlights the robustness of mixed microbial cultures for PHA biosynthesis.
• This approach contributes to sustainable plastic alternatives and waste valorization within the biorefinery concept.