Online Monitor the Viable Biomass Formation of U. maydis by Capacitance Measurement in Lab Scale Fermenter

Online capacitance (permittivity) measurements provide a simple, robust alternative to optical and gravimetric readouts for tracking viable biomass in Ustilago maydis. By applying an alternating electric field and measuring the dielectric response of intact cells, the signal reflects the volume of membrane-bound, living biomass and remains largely insensitive to turbidity, color, solids, or intracellular product accumulation. This is particularly beneficial during periods of lipid accumulation, where offline analytics can be influenced by changes in scattering or density. In contrast, capacitance maintains a closer correlation with the viable cell volume and enhances the clarity of growth phases and physiological shifts. This chapter introduces the measurement principle, practical probe handling with sterilizable, in situ sensors, and step-by-step setup in a 2 L lab-scale batch. Best practices for placement and autoclaving, baseline removal, logging intervals, and give guidance on sensor configuration, alongside straightforward calibration and interpretation strategies, will be discussed. Collectively, these procedures provide a reproducible workflow for continuous, non-invasive monitoring of viable biomass in U. maydis. This complements optical methods and enables more reliable kinetic analysis and process decisions during phases of poor offline analytics due to oil accumulation or solids within the system.