Detecting oxidized contaminants in water using sulfur-oxidizing bacteria

Area of Science:

• Environmental Science
• Microbiology
• Analytical Chemistry

Background:

• Oxidized contaminants in water pose risks to public health and ecosystems.
• Current detection methods may lack speed or sensitivity.
• Sulfur-oxidizing bacteria (SOB) have a unique metabolic pathway.

Purpose of the Study:

• To develop a novel, rapid, and reliable toxicity detection methodology for oxidized contaminants in water.
• To leverage the metabolic activity of SOB for contaminant sensing.
• To establish a sensitive early warning system for water pollution.

Main Methods:

• Utilized sulfur-oxidizing bacteria (SOB) to oxidize elemental sulfur to sulfuric acid.
• Monitored changes in electrical conductivity (EC) and pH as indicators of SOB activity.
• Introduced oxidized contaminants (nitrite, nitrate, perchlorate, dichromate) to assess their inhibitory effects on SOB.
• Operated the biosensor at low pH to enhance contaminant detection sensitivity.

Main Results:

• The SOB biosensor detected oxidized contaminants in the 5-50 ppb range.
• Nitrate was detected at concentrations as low as 10 ppm.
• Contaminant presence inhibited SOB, causing decreased effluent EC and increased pH.
• Low pH operation enhanced biosensor sensitivity by altering contaminant form.

Conclusions:

• The developed SOB biosensor provides rapid and sensitive detection of key oxidized water contaminants.
• The methodology offers an effective early warning system for potential environmental pollution.
• This approach surpasses the sensitivity of many existing whole-cell biosensors, particularly at low pH.