Bacterial poly(hydroxyalkanoates) as a source of chiral hydroxyalkanoic acids

Area of Science:

• Biotechnology
• Organic Chemistry
• Polymer Science

Background:

• Polyhydroxyalkanoates (PHA) are bacterial polyesters with enantiomerically pure R-configuration monomeric units.
• These R-hydroxyalkanoic acids are valuable chiral synthons for fine chemical, pharmaceutical, and medical applications.

Purpose of the Study:

• To develop an efficient method for producing chiral hydroxyalkanoic acid monomers from PHA.
• To investigate the optimal conditions for intracellular PHA degradation and monomer release.

Main Methods:

• Resuspending PHA-containing Pseudomonas putida cells in phosphate buffer at varying pH.
• Optimizing pH for intracellular PHA degradation and monomer release, with pH 11 showing the best results.
• Isolating and purifying monomers using solid phase extraction and reversed-phase semipreparative liquid chromatography.

Main Results:

• Optimal PHA degradation and monomer release occurred at pH 8-11, with pH 11 being most effective.
• At pH 11, over 90% (w/w) of PHA was degraded within 9 hours, yielding over 90% of monomers.
• Unsaturated monomers were also effectively produced, and purified 3-hydroxyoctanoic acid confirmed exclusive R-configuration.

Conclusions:

• An efficient method for producing chiral hydroxyalkanoic acid monomers from PHA has been established.
• Alkaline conditions, particularly pH 11, are highly effective for PHA degradation and monomer recovery.
• The method provides a scalable route to enantiomerically pure R-hydroxyalkanoic acids for industrial use.