The Effectiveness of Polyhydroxyalkanoate (PHA) Extraction Methods in Gram-Negative Pseudomonas putida U

Area of Science:

• Biotechnology
• Polymer Science
• Environmental Science

Background:

• Petroleum-based plastics cause pollution, driving demand for bioplastics like polyhydroxyalkanoates (PHAs).
• Commercializing PHAs is hindered by costly and environmentally harmful extraction processes.
• Developing sustainable PHA extraction methods is crucial for their wider adoption.

Purpose of the Study:

• To evaluate various physical and chemical methods for extracting poly-3-hydroxyoctanoate (P(3HO)) from *Pseudomonas putida* U.
• To identify an efficient and environmentally friendly PHA extraction process.
• To compare the yield and purity of P(3HO) obtained through different extraction techniques.

Main Methods:

• Six extraction methods were tested on lyophilized *Pseudomonas putida* U cells: boiling, sonication, sodium hypochlorite (NaClO), sodium dodecyl sulfate (SDS), sodium hydroxide (NaOH), and chloroform.
• Extraction efficiency, yield, and purity of P(3HO) were assessed.
• Spectroscopic and analytical techniques (FTIR, TGA, NMR, GPC) were employed for characterization.

Main Results:

• Physical methods (boiling, sonication) yielded 60-70% but with low P(3HO) recovery (30-40%).
• NaClO extraction gave high yields (80%) but with substantial impurities (70%).
• NaOH extraction showed moderate yields (50-80%) and purities (50-70%), with 0.05 M NaOH at 60°C being optimal for high purity and yield.

Conclusions:

• 0.05 M NaOH at 60°C is an effective and sustainable method for P(3HO) extraction from *Pseudomonas putida* U.
• This NaOH-based method offers a greener alternative to traditional solvent-based extraction.
• Optimized extraction contributes to the economic viability and environmental friendliness of PHA bioplastics.