Kinetics of bacterial potentiometric titrations: The effect of equilibration time on buffering capacity of Pantoea agglomerans suspensions

Leon Kapetas, Bryne T. Ngwenya, Alan M. MacDonald, Stephen C. Elphick

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Several recent studies have made use of continuous acid-base titration data to describe the surface chemistry of bacterial cells as a basis for accurately modelling metal adsorption to bacteria and other bio-materials of potential industrial importance. These studies do not share a common protocol; rather they titrate in different pH ranges and they use different stability criteria to define equilibration time during titration. In the present study we investigate the kinetics of bacterial titrations and test the effect they have on the derivation of functional group concentrations and acidity constants. We titrated suspensions of Pantoea agglomerans by varying the equilibration time between successive titrant additions until stability of 0.1 or 0.001 mV s(-1) was attained. We show that under longer equilibration times, titration results are less reproducible and suspensions exhibit marginally higher buffering. Fluorescence images suggest that cell lysis is not responsible for these effects. Rather, high DOC values and titration reversibility hysterisis after long equilibration times suggest that variability in buffering is due to the presence of bacterial exudates, as demonstrated by titrating supernatants separated from suspensions of different equilibration times. It is recommended that an optimal equilibration time is always determined with variable stability control and preliminary reversibility titration experiments. (C) 2011 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)481-486
Number of pages6
JournalJournal of Colloid and Interface Science
Volume359
Issue number2
DOIs
Publication statusPublished - 15 Jul 2011

Keywords / Materials (for Non-textual outputs)

  • Bacterial titrations
  • Stability criteria
  • Exudate production
  • SURFACE COMPLEXATION FRAMEWORK
  • BACILLUS-LICHENIFORMIS S-86
  • EXTRACELLULAR POLYMERS EPS
  • ACID-BASE PROPERTIES
  • METAL ADSORPTION
  • PROTON ADSORPTION
  • IONIC-STRENGTH
  • CALORIMETRIC MEASUREMENTS
  • SHEWANELLA-PUTREFACIENS
  • PSEUDOMONAS-PUTIDA

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