Biotechnology Letters

, Volume 22, Issue 18, pp 1487–1492

Preparation and characterization of native poly(3-hydroxybutyrate) microspheres from Ralstonia eutropha


  • G.J. Kim
    • Department of MicrobiologyChungnam National University
  • K.H. Bang
    • Department of MicrobiologyChungnam National University
  • Y.B. Kim
    • Department of Polymer EngineeringPaiChai University
  • Y.H. Rhee
    • Department of MicrobiologyChungnam National University

DOI: 10.1023/A:1005637827426

Cite this article as:
Kim, G., Bang, K., Kim, Y. et al. Biotechnology Letters (2000) 22: 1487. doi:10.1023/A:1005637827426


An efficient process for the preparation of poly(3-hydroxybutyrate) (PHB) microspheres with a narrow size distribution was developed. PHB was produced by a fed-batch culture of Ralstonia eutropha using fructose syrup as the sole carbon source. After autoclaving the bacteria, PHB granules, which accumulated in the cells, were isolated by a detergent/hypochlorite treatment and then spray-dried to obtain the microspheres. The diameters of the PHB microspheres ranged from 0.6 to 1.1 μm and the weight-average molecular weights were approximately 50 000 with polydispersity indexes of 5.0. The microspheres had a porous internal structure with an average porosity value of 72% and efficiently blocked UV light shorter than 220 nm. When isosorbide dinitrate was used as a model drug, the optimal drug loading concentration of the microspheres for controllable retardation was 3% (w/w). Almost 80% of the loaded drug (3%, w/w) was released within 12 h with typical sustained drug release behaviors.

drug carriermicrospherespoly(3-hydroxybutyrate)Ralstonia eutrophaspray drying

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© Kluwer Academic Publishers 2000