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Characterization and flocculating properties of an extracellular biopolymer produced from a Bacillus subtilis DYU1 isolate

Paper ID Volume ID Publish Year Pages File Format Full-Text
35867 45111 2007 10 PDF Available
Title
Characterization and flocculating properties of an extracellular biopolymer produced from a Bacillus subtilis DYU1 isolate
Abstract

Biopolymer DYU500 produced from Bacillus subtilis DYU1 was found to have excellent flocculating ability. With the addition of 40 mg-DYU500/L and 50 mM CaCO3, the optimum temperature for flocculation performance of DYU500 was 30 °C, giving the highest flocculating activity and rate of 13.5 and 97%, respectively. Analysis with Fourier transform infrared spectrophotometry (FT-IR), nuclear magnetic resonance spectrometry (NMR) and amino acid identification shows that the DYU500 biopolymer mainly possesses the structure of poly-glutamic acid (PGA). The average molecular weight of DYU500 was about (3.16–3.20) × 106 Da as determined by gel permeation chromatography. The major components of biopolymer DYU500 were total sugars, uronic acids, proteins and polyamides (homopolymer of glutamic acid), accounting for a weight ratio of approximate 14.9, 2.7, 4.4 and 48.7% (w/w), respectively. The flocculating activity of DYU500 in the kaolin suspension was markedly stimulated by the addition of bivalent cations Ca2+ or Mg2+ in optimum concentration ranges of about 0.15–0.90 and 0.10–0.90 mM, respectively. The synergistic effect of cations was most effective at a weak acidic or neutral pH (6.0–7.0). The flocculating activity of DYU500 linearly decreased with an increase in incubation temperature and the activity was completely lost when heating upon 120 °C, arising from the destruction of the polyamides structure of DYU500. Moreover, mechanisms describing the flocculation process with DYU500 were proposed based on the experimental observations.

Keywords
Biopolymer; Bioflocculant; Bacillus subtilis; Flocculating activity; Polyamides; Kaolin particles
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Characterization and flocculating properties of an extracellular biopolymer produced from a Bacillus subtilis DYU1 isolate
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 42, Issue 7, July 2007, Pages 1114–1123
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us