Biomass measurement by inductive permittivity.
An electrodeless, inductive permittivity probe is shown to reliably indicate fermentation biomass. By designing the probe based on electromagnetic induction, the electrode polarization artifact-common to electrode-based permittivity measurements of conductive solutions-is eliminated. The measurement of viable biomass concentration (X(V)) is precise and linear, with negligible interference, as shown for two bacteria, two yeasts, and two mammalian cells. The permittivity spectra often can be described by the three parameters of the Cole-Cole equation: the maximum (low-frequency) permittivity, the characteristic frequency (f(C)), and the Cole-Cole alpha. The f(C) and alpha have potential as relative indicators of cell size and morphology, respectively. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 289-304, 1997.
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