Sphaerotilus natans isolated from activated sludge and its production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Kang Liu, Hong Chua, Wai Hung Lo, Hugh Lawford, Peter Hoi Fu Yu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

6 Citations (Scopus)


Sphaerotilus natans is a sheathed bacterium existing in the activated sludge of wastewater treatment plants. It is one of the filamentous bacteria causing the bulking and foaming difficulties of activated sludge. Isolating the strain and culturing it in an axenic environment could not only provide the metabolic knowledge of the strains that would be useful in the development of wastewater treatment methods, but also could enable us to gain an understanding of the mechanism by which poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (poly[3-HB-co-3-HV]) is produced by this strain. This article reports the screening and isolation of the strain from the activated sludge using the Nile blue staining method together with Fourier transform infrared analysis. We investigated the ability of the selected strain to produce poly(3-HB-co-3-HV) cop01ymer using glucose and peptone, or by adding valeric acid or sodium propionate as precursor. Proper precursor feeding could dramatically enhance its 3HV content in the copolymer P(3HB-co-3HV). By controlling the different feeding times in fed-batch fermentation, different desired copolymers were obtained with 15, 40, and 70% 3HV mole fraction of the copolymer. Polymer properties were analyzed by gas chromatography, differential scanning calorimetry, thermo-gravimetry, and nuclear magnetic resonance analysis.
Original languageEnglish
Pages (from-to)1061-1073
Number of pages13
JournalApplied Biochemistry and Biotechnology - Part A Enzyme Engineering and Biotechnology
Publication statusPublished - 1 Jan 2002


  • Activated sludge
  • Copolymer
  • Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
  • Polymer properties
  • Sphaerotilus natans

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology


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