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Development of an automated water toxicity biosensor using Thiobacillus ferrooxidans for monitoring cyanides in natural water for a water filtering plant
Author(s) -
Okochi Mina,
Mima Koji,
Miyata Maki,
Shinozaki Youhei,
Haraguchi Satoshi,
Fujisawa Minoru,
Kaneko Masao,
Masukata Tadashi,
Matsunaga Tadashi
Publication year - 2004
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20193
Subject(s) - chemistry , ferrous , membrane , biosensor , sulfur , sulfuric acid , chromatography , clark electrode , nuclear chemistry , inorganic chemistry , electrode , biochemistry , organic chemistry , electrolyte
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 × 10 8 cells. The steady‐state current was obtained when concentration of FeSO 4 was above 3.6 m M at pH 3. The sensor response of T. ferrooxidans immobilized membrane for 5.0 μ M 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 μ M in a flow‐type monitoring system. Minimum detectable concentrations of KCN, Na 2 S, and NaN 3 were 0.5, 1.2, and 0.07 μ M , 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. © 2004 Wiley Periodicals, Inc.