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Lactate-enriched high-molecular-weight LAHB combines practical toughness with biodegradability Image caption: Reinforced expression of the lactate-polymerizing enzyme gene in recombinant bacteria leads to enhanced production of poly[(D-lactate)-co-(R)-3-hydroxybutyrate] (LAHB) with improved toughness and biodegradability.
Image Credit: Professor Seiichi Taguchi from Shinshu University, Japan
(CC BY 4.0)
Scientific Frontline: "At a Glance" Summary: Reinforced Enzyme Expression for High Production of Durable Lactate-Based Polyester
- Main Discovery: Researchers achieved the highest recorded production titer of high-molecular-weight poly[(D-lactate)-co-(R)-3-hydroxybutyrate] (LAHB) by reinforcing the gene expression of a lactate-polymerizing enzyme, successfully balancing mechanical toughness with marine biodegradability.
- Methodology: A lactate-polymerizing enzyme-expressing plasmid vector was introduced into the GS3 series of Cupriavidus necator bacteria using electroporation. The modified GSXd147 strain was then cultured through fed-batch fermentation using glucose as a carbon source, followed by mechanical, thermal, and biodegradability assessments of the purified polymer.
- Key Data: The modified bacterial strain produced 97 g/L dry cell weight comprising 70 wt% LAHB within 48 hours, yielding a record polymer titer of 68 g/L. The resulting material featured a 15.4 mol% lactate fraction, approximately 20 MPa tensile strength, 190% elongation at break, and achieved over 75% biodegradation in natural seawater within five weeks.
- Significance: Overcoming a major enzymatic bottleneck demonstrates that retaining the high molecular weight necessary for structural strength does not compromise the marine biodegradability of the polymer, establishing a highly functional and sustainable alternative to petroleum-based plastics.
- Future Application: This biotechnological approach enables the industrial-scale manufacturing of high-quality, bio-based plastic polymers for commercial packaging and goods, offering a practical solution to directly mitigate the global microplastics crisis.
- Branch of Science: Bioengineering, Biotechnology, and Polymer Chemistry.
- Additional Detail: The collaborative research involving Shinshu University, Kaneka Corporation, and the National Institute of Advanced Industrial Science and Technology will be published in Volume 246 of the journal Polymer Degradation and Stability.
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