In comparison to enzyme-based biosensors, microbial biosensors show lower analyte selectivity, slightly slower response times, but often much better stability. The inhibition of systems has proven successful in pyruvate monitoring ( Streptococcus faecium) by inhibiting glycolysis with iodoacetamide and tyrosine decarboxylase with tyramine, and in microbial detection of glutamic acid ( Bacillus subtilis) treated with chloromercuribenzoate and sodium fluoride to inhibit glucose uptake and metabolism. The former method has been successfully used for phenolics ( Trichosporon cutaneum), tyrosine ( Aeromonas phenologenes), and lactate ( Hansenula anomala). Whilst the sensor was insensitive to lactose, sucrose, and glucose, it responded with similar sensitivity to pyruvic acid, acetaldehyde, ethanol, ammonium acetate, and sodium acetate as well as to l- and d-lactic acids.Įnhanced selectivity and sensitivity has been achieved in two ways: (1) induction of the desired metabolic or membrane transport systems, or (2) the inhibition or suppression of undesired systems. An Acetobacter pasteurianus based oxygen electrode has been used for the determination of lactic acid, and shows good stability for 6 days, with a linear response range of 1×10 −4–1.5×10 −3 mol dm −3. These two examples also show good specificity for the target analyte, but many microbial biosensors respond to several compounds limiting their application for specific analyte detection. Limits of detection and detection ranges are often similar to, or overlapping with those of, enzyme-based systems, such as the examples given below. However, when specificity is required to allow analyte detection in complex mixtures of unknown composition interfering chemical species can become a problem.īacterial biocatalysts incorporated on to oxygen electrodes and ISEs typically have response times to analytes of between 5 and 15 min and show good stability for 7–30 days with storage normally in buffered saline between assays. Here, interference from other chemical species is not a problem, and microbial sensors perform well in this situation. The simplest type of analysis is that where only one component is present and the sensor is being used to determine concentration. Single-Component and Analyte-Specific Determination Trichosporon cutaneum/Pseudomonas putida/Bacillus licheniformisĪ BOD, biological oxygen demand. Potentiometric, fluorescence, luminescence

Istat glucose range