*2.1. Biosynthesis of P(3HB-co-95 mol% 4HB) Copolymer*

The bacteria strains used in this study were *Cupriavidus malaysiensis* USMAA1020 transformant harbouring additional PHA synthase gene from *Cupriavidus malaysiensis* USMAA2–4 to produce P(3HB-*co*-95 mol% 4HB) copolymer. The biosynthesis was carried out as previously described [23]. A preculture of 5% (*v/v*) of the working volume was transferred into 20 L fermenter (Biostat® C plus, Sartorius Stedim, German) containing mineral salts medium (MSM) with carbon precursors (1,4-butanediol and 1,6-hexanediol in the 1:5 ratio). The fermentation was carried out at 30 ◦C with an agitation speed of 200 rpm, the aeration rate of 1 vvm and controlled pH of 7 for 108 h. Sampling was done at intervals of every 12 h. The composition of PHA produced was determined by gas chromatography (GC) using Shimadzu Gas Chromatography GC-2014 according to methods previously described [24]. Endotoxin removal was carried out on extracted P(3HB-*co*-95 mol% 4HB) copolymer as previously described. The extracted polymer was characterized based on the molecular weight using Shimadzu GPC-2014 and tensile test using tensile testing machine (GoTech Al-3000, Shimadzu, Japan) [24].
