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

## TL;DR

This study shows how eucalyptus bark can be used to produce a sustainable biopolymer, poly(3-hydroxybutyrate), using eco-friendly methods.

## Contribution

The integration of eucalyptus bark as a feedstock with green processing methods for biopolymer production is novel.

## Key findings

- Eucalyptus bark hydrolysate supported high cell growth and P(3HB) content in Burkholderia thailandensis.
- Enzymatic extraction achieved 96% efficiency and 100% purity of P(3HB).
- The resulting biopolymer had properties comparable to commercial P(3HB).

## Abstract

This study integrates the valorization of a lignocellulose
material
into poly­(3-hydroxybutyrate), P­(3HB), with biopolymer extraction from
bacterial cells with the enzyme alcalase. The work focused on Burkholderia thailandensis DSM 13276 as the P­(3HB) producer
and on eucalyptus bark, a byproduct from the pulp industry, as the
sole feedstock for bacterial cultivation. The eucalyptus bark was
hydrolyzed by a cellulolytic enzymatic cocktail following steam explosion
and further subjected to ultrafiltration for enzyme recovery. The
resulting hydrolysate supported good cell growth, achieving a cell
dry weight of 7.67 ± 0.16 g/L within 72 h of cultivation, and
high P­(3HB) content (60.0 ± 2.19 wt %) in the bacterial cells,
clearly favoring biopolymer synthesis over cell growth, as demonstrated
by the polymer and growth yields (0.190 gP(3HB)/gsugar and 0.026 gX/gsugar, respectively). High extraction
efficiency (96%) and biopolymer purity (100 ± 3.38%) were reached
by enzymatic treatment, resulting in a sample with properties aligned
with those of commercial P­(3HB) in terms of molecular mass distribution,
crystallinity, and thermal properties. These findings demonstrate
the successful use of a sustainable feedstock together with the application
of environmentally friendly technologies based on the use of enzymes
for both lignocellulosic saccharification and biopolymer recovery
to develop high-quality bioplastics, advancing the goals of a circular
bioeconomy.