A novel biosensor for detecting toxicity in water using sulfur-oxidizing bacteria

Sang Eun Oh*, Sedky H.A. Hassan, Steven W. Van Ginkel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

57 Citations (Scopus)


A novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed for the rapid and reliable detection of toxic chemicals in water. The methodology exploits the ability of SOB to oxidize sulfur particles in the presence of oxygen to produce sulfuric acid according to the following equation: S + H2O + 1.5O2 → SO 42- + 2H+, ΔG°′ = -587.1 kJ/reaction. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH as SOB convert insoluble sulfur particles to sulfate and protons. The proposed technique is validated using EC and pH data. Using a synthetic stream water (EC = 0.12 mS/cm and pH 7.2), the baseline steady-state EC and pH values were ∼1.0 mS/cm and ∼2.5 over 30 days of testing when hexavalent chromium (Cr6+) was not added to the system. When Cr 6+ was added to the system, the effluent EC decreased and the pH increased due to inhibition of SOB. We found that the system can detect Cr 6+ at a concentration of 5 ppb which is lower than any method to date.

Original languageEnglish
Pages (from-to)17-21
Number of pages5
JournalSensors and Actuators, B: Chemical
Issue number1
Publication statusPublished - May 20 2011
Externally publishedYes


  • Biosensor
  • Electrical conductivity
  • Sulfur particles
  • Sulfur-oxidizing bacteria
  • Toxicity

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry


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