Pure biomolecules such as enzymes, antibodies and the like can provide identification elements for various biosensors. Although these purified biomolecules have high reactivity, they are usually expensive and have poor stability. Therefore, in environmental monitoring biosensors, whole microbial cells such as bacteria, yeast, and fungi are generally used as identification elements. These microorganisms are usually separated from active muddy sediments, river water, rubble and soil. Microbial sensors developed using microbial metabolic functions allow for the identification and analysis of contaminants.
(1) BOD microbial sensor Determination of biochemical oxygen demand (BOD) is a typical application of microbial sensors. The traditional method of measuring BOD takes 5 days, and the operation is complicated. The BOD microbial sensor can measure the result in only 15 minutes. The sensor consists of an oxygen electrode and a microbial immobilization membrane (microorganisms are Pseudomonas, Hansenula, Active Mud, Trichosporon, Bacillus subtilis, etc.). When organic matter (such as glucose) is added, the immobilized microorganism decomposes the organic matter, causing the microbial respiration to increase, resulting in a decrease in dissolved oxygen, thereby lowering the oxygen electrode current response until the measured solution diffuses oxygen to the solidified microbial membrane and the microorganism A balance is reached between the amount of oxygen consumed by the breath, and a corresponding steady current value is obtained.
(2) The phenomenon of water color anomalies caused by the outbreak of some small plankton in the red tide waters of the Jianzhou red tide waters, which are caused by algae pollution, is called red tide, mainly occurring in offshore waters. Red tides have severely damaged ecosystems in the waters. Monitoring of plankton causing red tides has become an important issue. A plankton called Chattonclla is an important species that causes red tides, and biosensors that monitor such plankton have been developed abroad. The principle is to detect chemiluminescence produced by such organisms or co-metabolites. In addition, other algal biosensors that detect red tides have also been developed. For example, the mechanism of action of a biosensor for monitoring cyanobacteria is that the algae cell has a kind of alginate, which emits a unique fluorescence spectrum, which can be effectively monitored by measuring the fluorescence.
(3) Sulfide microbial sensors are commonly used in the determination of sulfides by spectrophotometry and iodometric methods. The former color development conditions are difficult to control and the operation is cumbersome; the latter reagents consume large amounts and cost. Microbial sensor method is a new method with simple equipment, simple operation and low cost. Preparation process of sulphide microbial sensor: a strain of specific, autotrophic, aerobic thiobacillus thiooxidans isolated from acidic soil near pyrite, and the appropriate amount of bacteria in the two cellulose acetate membranes Intercalation, making a sandwich microbial membrane; filling the inner cavity of the oxygen electrode with an electrolyte, covering the surface of the gold cathode with a polytetrafluoroethylene film, and then adhering the interlayer film to the polytetrafluoroethylene film to form a sulfide microorganism sensor.
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