Mixed culture fermentation and media optimization by response surface model: Streptomyces and Brachybacterium species in bioflocculant production

Molecules. 2014 Jul 29;19(8):11131-44. doi: 10.3390/molecules190811131.

Abstract

The biofloculant production potential of a consortium of Streptomyces and Brachybacterium species were evaluated. Optimum bioflocculant yields (g/L) and flocculation activities (%) were observed for the following preferred nutritional sources: glucose (56%; 2.78 ± 0.15 g/L), (NH4)2NO3 (53%; 2.81 ± 0.37 g/L) and CaSO4 · H2O (47%; 2.19 ± 0.13 g/L). A Plackett-Burman design revealed the critical fermentation media components. The concentrations of these components were optimized [glucose; 16.0, (NH4)2NO3; 0.5 and CaSO4 · H2O; 1.2 (g/L)] through a central composite design with optimum bioflocculant yield of 3.02 g/L and flocculation activity of 63.7%. The regression coefficient (R(2) = 0.6569) indicates a weak estimation of the model's adequacy and a high lack-of-fit value (34.1%). Lack of synergy in the consortium may have been responsible for the model inadequacy observed. FTIR spectrometry showed the bioflocculant to be a heteropolysaccharide, while SEM imaging revealed an amorphous loosely arranged fluffy structure with interstial spacing of less than 1 µm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinomycetales / growth & development
  • Actinomycetales / metabolism*
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / isolation & purification
  • Culture Media* / chemistry
  • Energy Metabolism
  • Fermentation*
  • Streptomyces / growth & development
  • Streptomyces / metabolism*

Substances

  • Bacterial Proteins
  • Culture Media