Microbial Polyhydroxyalkanoates (PHAs): From Synthetic Biology to Industrialization

Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH): Synthesis, properties, and applications - A review

“…However, due to certain drawbacks of PHB, such as its brittleness and low toughness, copolymers of PHB with a comonomer belonging to the PHA types have been developed to tackle better processability, higher ductility, and better impact properties. These common copolymers could be listed as poly ( hydroxyhexanoate) [P(3HB-co-3HHx), PHBHHx or PHBH] [12]. Figures 2b and 2c illustrate the chemical structures of PHBV and PHBH copolymers where x, y, z and t subunits represent the number of monomeric units in the copolymer structure that could be tailored to obtain defined macromolecular structures Compared to PHB and PHBV, PHBH has revealed a wider processing window with better thermal stability.…”

Tailoring the HHx monomer content of P(HB-co-HHx) by flexible substrate compositions: scale-up from deep-well-plates to laboratory bioreactor cultivations

“…All abovementioned studies, even if they achieved lower biomass yields due to the use of less urea as nitrogen source (about half of this study) and less comparability along the tested mixtures, are based on the same principle and prove that it is plausible to extend our strategy to other feedstocks. Another different approach to control the HHx fraction of P(HB- co -HHx) on a molecular level was presented by controlling the expression of the phaJ gene of R. eutropha , involved in the generation of HHx precursors, showing that copolymers with HHx molar contents ranging from 2.8–10.7 mol% could be obtained ( Miyahara et al, 2021 ). Arikawa et al recently reported the tailored production of P(HB- co -HHx) with HHx contents up to 36 mol% by the deletion of the ß -ketothiolase gene together with the overexpression of the (R)-specific enoyl-Coa hydratase and PhaC synthase ( Arikawa and Sato, 2022 ).…”

Microbial Platform for Tailor-made Production of a Biodegradable Polylactide Modifier: Ultrahigh-Molecular-Weight Lactate-Based Polyester LAHB

“…Additionally, it offers excellent biodegradability and facilitates the efficient utilization of renewable feedstocks. , PHBH is commercially manufactured by KANEKA Co. Ltd. under the trade name KANEKA Biodegradable Polymer GreenPlanet, and is currently used for various applications, including the production of straws, shopping bags, cutlery, and single-use coffee capsules. The annual production capacity of GreenPlanet reached 20,000 tons in 2024, and the demand is expected to grow further as an alternative to conventional fossil fuel-based commodity plastic . The industrialization of KANEKA PHBH has inspired further investigation of PHA on a global scale.…”

“…In contrast, polyhydroxyalkanoate (PHA) is a naturally occurring polyester that is biodegradable in various environments including the ocean. Over 160 members of the PHA family have been identified, including various combinations resulting from copolymerization. − The monomeric variation of PHA allows optimization of its physical properties through design of controlled random and sequence-regulated copolymers. , For example, poly­[3-hydroxybutyrate (3HB)- co -3-hydroxyhexanoate (3HHx)] (PHBH) has been industrially produced and tailor-made with 6 mol % 3HHx for hard-type and 11 mol % 3HHx for soft-type PHBH . The customizable composition of highly crystalline (3HB) and elastomeric (3HHx) units effectuates the acquisition of a broader processing window, enhanced thermal stability, and efficacious mechanical performance.…”