Sustainable Production of Poly(3-hydroxybutyrate) Using Eucalyptus Bark: Integration with Green Downstream Processing

Area of Science:

• Biotechnology
• Polymer Science
• Sustainable Chemistry

Background:

• Lignocellulosic biomass represents an abundant, underutilized resource for biopolymer production.
• Developing cost-effective and environmentally friendly methods for biopolymer extraction is crucial for commercial viability.

Purpose of the Study:

• To integrate lignocellulose valorization with biopolymer extraction for poly-(3-hydroxybutyrate) (P-(3HB)) production.
• To utilize eucalyptus bark as a sole feedstock for bacterial cultivation and P-(3HB) synthesis.
• To achieve high P-(3HB) yield and purity using enzymatic hydrolysis and extraction.

Main Methods:

• Hydrolysis of eucalyptus bark using a cellulolytic enzymatic cocktail after steam explosion.
• Cultivation of *Burkholderia thailandensis* DSM 13276 on bark hydrolysate.
• Extraction of P-(3HB) using the enzyme alcalase.
• Enzyme recovery via ultrafiltration.

Main Results:

• Achieved a cell dry weight of 7.67 g/L and high P-(3HB) content (60.0 wt %) in bacterial cells.
• Demonstrated high polymer and growth yields (0.190 g_P(3HB)/g_sugar and 0.026 g_X/g_sugar).
• Obtained 96% extraction efficiency and 100% biopolymer purity with properties comparable to commercial P-(3HB).

Conclusions:

• Successfully valorized eucalyptus bark into high-quality P-(3HB) bioplastics using sustainable enzymatic technologies.
• Demonstrated the feasibility of using a circular bioeconomy approach for bioplastic production.
• Highlighted the potential of enzymatic processes for both lignocellulosic saccharification and biopolymer recovery.