Biosynthesis and Degradation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Alcaligenes sp. SH-69

Alcaligenes sp. SH-69에서의 Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) 생합성 및 분해

  • Ryu, Kang-Eun (Department of Microbiology, Chungnam National University) ;
  • Choi, Gang Guk (Department of Microbiology, Chungnam National University) ;
  • Park, Sang Kyu (Department of Microbiology, Chungnam National University) ;
  • Kim, YoungBaek (Department of Polymer Materials, PaiChai University) ;
  • Rhee, Young Ha (Department of Microbiology, Chungnam National University)
  • 류강은 (충남대학교 자연과학대학 미생물학과) ;
  • 최강국 (충남대학교 자연과학대학 미생물학과) ;
  • 박상규 (충남대학교 자연과학대학 미생물학과) ;
  • 김영백 (배재대학교 신소재공학부 고분자학과) ;
  • 이영하 (충남대학교 자연과학대학 미생물학과)
  • Received : 1998.09.10
  • Accepted : 1998.10.19
  • Published : 1998.12.01

Abstract

The cyclic metabolism of poly(3-hydroxyhutyrate-co-3-hydroxyvalerate) synthesized from glucose by Alcaligenes sp. SH-69 in the presence or absence of new carbon substrate was investigated. In batch culture, the content and weight average molecular weight of the copolymer already stored in the cell decreased rapidly when there was no other carbon source available. After the depletion of carbon source, the amount of high molecular weight copolymer decreased more rapidly than that of low molecular weight copolymer, and as a result, average molecular weight distribution shifted to the lower value. The addition of a mixture of glucose and levulinic acid when the initial carbon substrate, glucose, was nearly depleted supported the continual increase in cell mass and the accumulation of poly(3HB-co-3HV) with high molar fraction of 3HV. However, solvent fractionation of the polymer with acetone revealed the degradation of pre-existing polyhydroxyalkanoale (PHA) in parallel with the synthesis of PHA from new carbon substrate. Even though PHAs obtained from each substrate alone were the copolymer of 3HB and 3HV, it was found that the polymer accumulated in the cells grown by sequential feeding was mainly physical mixture of two poly(3HB-co-3HV) copolymers containing different molar fractions of 3HV.

Keywords

biosynthesis;copolymer;intracellular degradation;polyhydroxyalkanoate;poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Acknowledgement

Supported by : 교육부 기초과학연구소