Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] biotechnological production: challenges and opportunities

Author:de Macedo, Matheus A., et al.

Journal:

Biomass Conversion and Biorefinery (2022): 1-20.

Abstract:Polyhydroxyalkanoates (PHA) compose a family of biodegradable and biocompatible polyesters, and are a potential alternative to the use of petrochemical plastics. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] is an extensively studied copolymer member of the PHA family due to its medical applications. Usually, 4HB monomer incorporation depends on the supply of structurally related carbon sources, such as 4-hydroxybutyric acid, γ-Butyrolactone (GBL), and 1,4-butanediol, although it can occur in some bacteria when supplying unrelated carbon sources, such as glucose. This review is focused on the bacterial cell factories and on the economic aspects of P(3HB-co-4HB) production, discussing strategies to broadly enable its biotechnological production on an industrial scale. Articles discussing the genetic engineering and cultivation conditions of major promising bacterial platforms to enhance P(3HB-co-4HB) production (Cupriavidus necator,Escherichia coli,Burkholderia sacchari,Halomonas bluephagenesis, and others) are reviewed, describing and comparing the advantages and disadvantages of each one. Economic aspects of large-scale P(3HB-co-4HB) manufacturing in the context of a biorefinery are analyzed, highlighting the main bottlenecks of the bioprocess. Improvement of bacterial conversion rate of GBL to 4HB and the use of cheaper substrates for 4HB incorporation to the copolymer, through the development of novel pathways and newly isolated strains, should be the main targets for future studies.