Development of an automated water toxicity biosensor using Thiobacillus ferrooxidans for monitoring cyanides in natural water for a water filtering plant

Mina Okochi, Koji Mima, Maki Miyata, Youhei Shinozaki, Satoshi Haraguchi, Minoru Fujisawa, Masao Kaneko, Tadashi Masukata, Tadashi Matsunaga

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Abstract

An on-line biosensor consisting of immobilized Thiobacillus ferrooxidans and an oxygen electrode was developed for automated monitoring of acute toxicity in water samples. T. ferrooxidans is an obligatory acidophilic, autotrophic bacterium and derives its energy by the oxidation of ferrous ion, elemental sulfur, and reduced sulfur compounds including metal sulfides. The assay is based on the monitoring of a current increase by addition of toxicoids, which is caused by the inhibition of bacterial respiration and decrease in oxygen consumption. Optimum cell number on the membrane was 5.0 × 108 cells. The steady-state current was obtained when concentration of FeSO 4 was above 3.6 mM at pH 3. The sensor response of T. ferrooxidans immobilized membrane for 5.0 μM KCN was within an error of 10% for 30 membranes. A linear relationship was obtained at KCN concentration in the range of 0.5-3.0 μM in a flow-type monitoring system. Minimum detectable concentrations of KCN, Na2S, and NaN3 were 0.5, 1.2, and 0.07 μM, respectively. The monitoring system contained two biosensors and these sensors were cleaned with sulfuric acid (pH 1.5) twice a day. This treatment could remove fouling on microbial immobilized membrane by natural water and ferrous precipitation in the flow cell. This flow-type monitoring sensor was operated continuously for 5 months. Also, T. ferrooxidans immobilized membrane can be stored for one month at 4°C when preserved with wet absorbent cotton under argon gas.

Original languageEnglish
Pages (from-to)905-911
Number of pages7
JournalBiotechnology and Bioengineering
Volume87
Issue number7
DOIs
Publication statusPublished - 2004 Sep 30
Externally publishedYes

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Keywords

  • Biosensor
  • Cyanide sensor
  • Flow monitoring system
  • Thiobacillus ferrooxidans
  • Water toxicity

ASJC Scopus subject areas

  • Biotechnology
  • Microbiology

Cite this

Okochi, M., Mima, K., Miyata, M., Shinozaki, Y., Haraguchi, S., Fujisawa, M., Kaneko, M., Masukata, T., & Matsunaga, T. (2004). Development of an automated water toxicity biosensor using Thiobacillus ferrooxidans for monitoring cyanides in natural water for a water filtering plant. Biotechnology and Bioengineering, 87(7), 905-911. https://doi.org/10.1002/bit.20193