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High-frequency, dielectric spectroscopy for the detection of electrophysiological/biophysical differences in different bacteria types and concentra…

A new interesting article has been published in Anal Chim Acta. 2018 Oct 22;1028:86-95. doi: 10.1016/j.aca.2018.04.045. Epub 2018 Apr 23. and titled:

High-frequency, dielectric spectroscopy for the detection of electrophysiological/biophysical differences in different bacteria types and concentra…

Authors of this article are:

Russel M, Sophocleous M, JiaJia S, Xu W, Xiao L, Maskow T, Alam M, Georgiou J.

A summary of the article is shown below:

This paper describes a novel technique to quantify and identify bacterial cultures of Bacillus Subtilis (2.10-1.30 × 109 CFU mL-1) and Escherichia Coli (1.60-1.00 × 109 CFU mL-1), in corn oil using dielectric spectroscopy at elevated frequencies of 0.0100-20.0 GHz. This technique is using the electrophysiological/biophysical differences (e.g. gram positive and gram negative) between various bacteria types, as a basis to distinguish between bacteria concentrations and bacteria types. A close-ended, coaxial probe of 20.0 mm long sample-holder was developed and used to calculate the dielectric constant from the measured S parameters of the bacterial cultures, using the Nicolson-Ross-Weir method. This technique shows a linear relationship (r2 ≥ 0.999) between the dielectric constant and the cell concentration, at 16.0 GHz. The sensitivity of the technique is 0.177 × 109 (CFU mL-1)-1 for B. Subtilis (with a size of 10.0 × 1.00 μm), 0.322 × 109 (CFU mL-1)-1 for E. Coli (with a size of 2.00 × 0.500 μm) and 0.913 × 109 (CFU mL-1) -1 for their 1:1 mixture, while the response time is 60.0s. The dependency of dielectric constant on the bacterial cell concentration at a given frequency can be potentially exploited for measuring bacterial concentrations and biophysical differences.

Check out the article’s website on Pubmed for more information:



This article is a good source of information and a good way to become familiar with topics such as:

Bacillus subtilis;Bacterial Typing Techniques;Electric Conductivity;Escherichia coli

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