Dataset Information

Biosynthesis of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from CO₂ by a Recombinant Cupriavidusnecator.

ABSTRACT: The copolyester of 3-hydroxybutyrate (3HB) and 3-hydoxyhexanoate (3HHx), PHBHHx, is one of the most practical kind of bacterial polyhydroxyalkanoates due to its high flexibility and marine biodegradability. PHBHHx is usually produced from vegetable oils or fatty acids through β-oxidation, whereas biosynthesis from sugars has been achieved by recombinant strains of hydrogen-oxidizing bacterium Cupriavidus necator. This study investigated the biosynthesis of PHBHHx from CO₂ as the sole carbon source by engineered C. necator strains. The recombinant strains capable of synthesizing PHBHHx from fructose were cultivated in a flask using complete mineral medium and a substrate gas mixture (H₂/O₂/CO₂ = 8:1:1). The results of GC and ¹H NMR analyses indicated that the recombinants of C. necator synthesized PHBHHx from CO₂ with high cellular content. When 1.0 g/L (NH₄)₂SO₄ was used as a nitrogen source, the 3HHx composition of PHBHHx in the strain MF01∆B1/pBBP-ccr_MeJ4a-emd was 47.7 ± 6.2 mol%. Further investigation demonstrated that the PHA composition can be regulated by using (R)-enoyl-CoA hydratase (PhaJ) with different substrate specificity. The composition of 3HHx in PHBHHx was controlled to about 11 mol%, suitable for practical applications, and high cellular content was kept in the strains transformed with pBPP-ccr_MeJ_Ac-emd harboring short-chain-length-specific PhaJ.

SUBMITTER: Tanaka K

PROVIDER: S-EPMC8615203 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:Poly(hydroxybutyrate-co-hydroxyhexanoate) [P(HB-co-HHx)] and poly(hydroxybutyrate-co-hydroxyvalerate-co-hydroxyhexanoate) [P(HB-co-HV-co-HHx)] demonstrate interesting mechanical and thermal properties as well as excellent biocompatibility, making them suitable for multiple applications and notably biomedical purposes. The production of such polymers was described in Rhodospirillum rubrum, a purple nonsulfur bacteria in a nutrient-lacking environment where the HHx synthesis is triggered by the presence of hexanoate in the medium. However, the production of P(HB-co-HHx) under nutrient-balanced growth conditions in R. rubrum has not been described so far, and the assimilation of hexanoate is poorly documented. In this study, we used proteomic analysis and a mutant fitness assay to demonstrate that hexanoate assimilation involve β-oxidation and the ethylmalonyl-coenzyme A (CoA) (EMC) and methylbutanoyl-CoA (MBC) pathways, both being anaplerotic pathways already described in R. rubrum. Polyhydroxyalkanoate (PHA) production is likely to involve the de novo fatty acid synthesis pathway. Concerning the polymer composition, HB is the main component of the polymer, probably as acetyl-CoA and butyryl-CoA are intermediates of hexanoate assimilation pathways. When no essential nutrient is lacking in the medium, the synthesis of PHA seems to help maintain the redox balance of the cell. In this framework, we showed that the fixation of CO2 is required to sustain the growth. An increase in the proportion of HHx in the polymer was observed when redox stress was engendered in the cell under bicarbonate-limiting growth conditions. The addition of isoleucine or valerate in the medium also increased the HHx content of the polymer and allowed the production of a terpolymer of P(HB-co-HV-co-HHx). IMPORTANCE The use of purple bacteria, which can assimilate volatile fatty acids, for biotechnological applications has increased, since they reduce the production costs of added-value compounds such as PHA. P(HB-co-HHx) and P(HB-co-HV-co-HHx) have demonstrated interesting properties, notably for biomedical applications. In a nutrient-lacking environment, R. rubrum is known to synthesize such polymers when hexanoate is used as the carbon source. However, their production in R. rubrum in non-nutrient-lacking growth conditions has not been described so far, and the assimilation of hexanoate is poorly documented. As the carbon source and its assimilation directly impact the polymer composition, we studied under non-nutrient-lacking growth conditions the assimilation pathway of hexanoate and PHA production in R. rubrum. Proteomic analysis and mutant fitness assays allowed us to explain PHA production and composition. An increase in HHx content of the polymer and production of P(HB-co-HV-co-HHx) was possible using the knowledge gained on metabolism under hexanoate growth conditions.

Dataset Information

Biosynthesis of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from CO₂ by a Recombinant Cupriavidusnecator.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

Biosynthesis of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from CO2 by a Recombinant Cupriavidusnecator.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Biosynthesis of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from CO₂ by a Recombinant Cupriavidusnecator.