Spectroscopic study of extracellular polymeric substances from Bacillus subtilis: Aqueous chemistry and adsorption effects

Anselm Omoike, Jon Chorover

Research output: Contribution to journalReview articlepeer-review

285 Scopus citations

Abstract

Reactions at ionizable functional groups in extracellular polymeric substances (EPS) from Bacillus subtilis are found to affect aqueous phase conformation and adsorption to mineral surfaces. Characterization by HPSEC, XPS, and FTIR indicates a wide range in apparent molecular mass (0.57-128 kDa), with functional group composition depending on cell growth phase (exponential vs stationary) and location in suspension (free vs cell-bound). ATR-FTIR spectroscopy shows complexation and dissociation of protons on acidic functional groups that result in α-helical protein conformation at pH < 2.6 and random coil (unordered) conformation at higher pH (>6). EPS exhibit higher affinity for adsorption to α-FeOOH than amorphous SiO2 because of surface charge effects. Increased amide II band intensity and an amide I band shift to higher frequency indicate changes in protein structure upon adsorption. Goethite-EPS spectra show emergent vibrations consistent with P-O-Fe bonding, which suggests a role of phosphodiester groups in the adsorption reaction.

Original languageEnglish (US)
Pages (from-to)1219-1230
Number of pages12
JournalBiomacromolecules
Volume5
Issue number4
DOIs
StatePublished - Jul 1 2004

ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry

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