초록
<P><B>Abstract</B></P><P><B>BACKGROUND</B></P><P><B>The incorporation of 4HB units into P(3HB) improves the material application potential as the copolymer exhibits a wide range of physical properties ranging from crystalline plastic to elastic rubber depending on the copolymer composition. Thus, the prospects of synthesizing P(3HB‐<I>co</I>‐4HB) copolymer with various compositions of 4HB would increase its effectiveness as biomaterial.</B></P><P><B>RESULTS</B></P><P><B>The residual cell dry weight (RCDW) and PHA concentration obtained under optimized conditions, namely C/N ratio 30, K<SUB>2</SUB>HPO<SUB>4</SUB> 6.1 g L<SUP>‐1</SUP>, incubation period 66 h, temperature 32°C and volume‐to‐flask ratio 47/250 mL increased from 2.9 g L<SUP>‐1</SUP> to 4.9 g L<SUP>‐1</SUP> and 4.2 g L<SUP>‐1</SUP> to 7.6 g L<SUP>‐1</SUP>, respectively. P(3HB‐<I>co</I>‐4HB) with varied <I>M</I><SUB>n</SUB> between 26 kDa and 270 kDa were successfully synthesized using combinations of oleic acid, 1,6‐hexanediol and/or 1,4‐butanediol. The tensile strength and Young's modulus of the copolymers varied from 2 MPa to 24 MPa and 13 MPa to 192 MPa, respectively. <I>T</I><SUB>m</SUB> and <I>T</I><SUB>g</SUB> decreased with increasing 4HB molar fractions from 170°C to 68°C and 2.5°C to −31°C, respectively.</B></P><P><B>CONCLUSION</B></P><P><B>Oleic acid and (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> was the best carbon and nitrogen source for PHA biosynthesis. P(3HB‐<I>co</I>‐4HB) copolymer with targeted 4HB molar fractions ranged from 0–65 mol% were synthesized using combinations of two or more carbon substrates by <I>Cupriavidus</I> sp. USMAA2‐4 (DSM 19379) using mixture design. © 2013 Society of Chemical Industry</B></P>