African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 5233

Full Length Research Paper

Characterization of a thermostable polysaccharide bioflocculant produced by Virgibacillus species isolated from Algoa bay

Cosa Sekelwa*, Ugbenyen M. Anthony, Mabinya L. Vuyani and Okoh I. Anthony
Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa.
Email: [email protected]

  •  Accepted: 26 April 2013
  •  Published: 04 June 2013


We evaluated the bioflocculant production by Virgibacillus species isolated from a marine environment in the Eastern Cape Province of South Africa. Culture conditions for optimal production of the bioflocculant included: glucose as sole carbon source (flocculating activity 91.8%); complex nitrogen source (urea + yeast extract + (NH4)2SO4); inoculum size of 2% (v/v); initial pH 10; and calcium as mediating factor. Optimum dose of the purified bioflocculant for the clarification of 4 g/l kaolin clay suspension at neutral pH was 0.3 mg/ml. Chemical analysis of the purified bioflocculant revealed it to be mainly composed of uronic acids (87% w/w). Scanning electron microscopic observations were indicative of a porous bioflocculant structure. Fourier transform infrared (FTIR) spectrum revealed the presence of carboxyl and hydroxyl groups whilst the themogravimetric analysis (TGA) showed degradation temperature (Td) of 150°C. The bioflocculant appears to hold promise in vast biotechnological applications in a more environmentally friendly and economical manner.


Key words: Virgibacillus sp., bioflocculant, thermostable, polysaccharide.