Application of AC-Impedance in microbial cultivation system for in-situ biomass measurements

Abstract

BackgroundQuantification of the biomass is an important measurement in the microbial fermentation process. However, the conventional method for biomass quantification using UV–visible spectroscopy usually associates with several limitations such as tedious, time-consuming and high risk of contamination. The use of electrical impedance spectroscopy (EIS) is emerged as a cost- and time-saving approach with low risk of contamination for the quantification of microbial biomass. MethodsThe application of AC-impedance in fermenter for the biomass quantification of Saccharomyces cerevisiae yeast and Chlamydomonas reinhardtii microalgae was investigated in this study. The cell dry weight (CDW, g L−1) was directly determined without the removal of sample from the fermenter. Significant findingsThe findings revealed that the correlation between impedance ohmic resistance (Rs) and cells concentration (CDW) can be expressed using linear regression analysis with the generation of a series of equations by piecewise and single functions. The evaluation of impedance Rs of blank cultivation medium as calibration standard was performed and the measurement models was verified in which controlled mean absolute percentage error (MAPE) under 20% of cells concentration was achieved.