The proton extrusion of growing yeast cultures as an on‐line parameter in fermentation processes: Determination of biomass production and substrate consumption in batch experiments with Candida maltosa EH 15 D

Using the proton extrusion of growing yeast cultures (calculated from the alkali consumption required to maintain a constant pH‐value) it is possible to describe the growth of yeasts and the growth‐related substrate consumption on‐line and to do so more exactly than by determining these values with usual off‐line methods. In batch experiments with Candida maltosa in a mineral salt medium clear linear relationships could be demonstrated between the proton extrusion n H+ and the increase of biomass concentration (determined as dry weight, optical density and protein according to a modified LOWRY‐method) as well as substrate consumption ( n ‐hexadecane and NH + 4 as the C‐ and N‐sources respectively). The biochemical basis of the proton extrusion seems to be connected with the NH + 4 ‐metabolism. The simple on‐line registration of the proton extrusion offers various possibilities to use this value for control of fermentation processes.