Enhanced production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer with manipulated variables and its properties

Abstract

Cupriavidus sp. USMAA1020, a local isolate was able to biosynthesis poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer with various 4HB precursors as the sole carbon source. Manipulation of the culture conditions such as cell concentration, phosphate ratio and culture aeration significantly affected the synthesis of P(3HB-co-4HB) copolymer and 4HB composition. P(3HB-co-4HB) copolymer with 4HB compositions ranging from 23 to 75 mol% 4HB with various mechanical and thermal properties were successfully produced by varying the medium aeration. The physical and mechanical properties of P(3HB-co-4HB) copolymers were characterized by NMR spectroscopy, gel-permeation chromatography, tensile test, and differential scanning calorimetry. The number-average molecular weights (M (n)) of copolymers ranged from 260 x 10(3) to 590 x 10(3)Da, and the polydispersities (M (w)/M (n)) were between 1.8 and 3.0. Increases in the 4HB composition lowered the molecular weight of these copolymers. In addition, the increase in 4HB composition affected the randomness of copolymer, melting temperature (T (m)), glass transition temperature (T (g)), tensile strength, and elongation to break. Enzymatic degradation of P(3HB-co-4HB) films with an extracellular depolymerase from Ochrobactrum sp. DP5 showed that the degradation rate increased proportionally with time as the 4HB fraction increased from 17 to 50 mol% but were much lower with higher 4HB fraction. Degradation of P(3HB-co-4HB) films with lipase from Chromobacterium viscosum exhibited highest degradation rate at 75 mol% 4HB. The biocompatibility of P(3HB-co-4HB) copolymers were evaluated and these copolymers have been shown to support the growth and proliferation of fibroblast cells.

Biosynthesis and Characterization of Poly (3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) Terpolymer with Various Monomer Compositions by Cupriavidus sp. USMAA2-4

“…Differential scanning calorimeter (DSC) (Pyris DSC, PerkinElmer) was used to determine the thermal properties of the terpolymer. This procedure was carried out according to Vigneswari et al [20]. The physical properties of the terpolymers were characterized using tensile machine (GOTECH A1-3000) to determine the tensile strength, Young's modulus, and elongation to break.…”

Biosynthetic enhancement of single-stage Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) production by manipulating the substrate mixtures

“…USMAA1020 was known to be a potential producer of copolymer P(3HB-co-4HB) [1]. In twostage fermentation, the strain was reported to be able to accumulate 75 mol% 4HB monomer while only 14 mol% 4HB was achieved in single-stage cultivation by using γ-butyrolactone as the sole carbon source [1,28]. It was concluded that in single-stage cultivation, the bacterium has the ability to accumulate high PHA content with lower 4HB molar fraction [1].…”

“…The Mark-Houwink constant for polystyrene in chloroform was taken as K = 0.011 mL/ mg and α = 0.73, whereas those for P(3HB) in chloroform were taken as K = 0.016 mL/mg and α = 0.76 [19]. The mechanical test of PHA films were carried out in the form of dumbbell shapes (4 mm × 75 mm) using a Universal Testing Machine (GOTECH A1-3000 with U60 software, Taiwan) [28]. The thermal properties of the polymer films were determined using Pyris 1 differential scanning calorimetry (DSC) (Perkin Elmer, US).…”

Regulating the molar fraction of 4-hydroxybutyrate in Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by biological fermentation and enzymatic degradation

“…The study on enzymatic degradation was carried out using depolymerase enzyme from Acidovorax sp as previously mentioned (Vigneswari et al 2009). The P(3HB-co-70 mol%4HB) films used had an initial weight of 0.011 g, film dimensions of 10 9 10 mm and thickness, 0.06 mm.…”