On-line biomass monitoring by capacitance measurement.
An in-situ, steam-sterilizable capacitance probe was used to follow the biomass concentration on-line, in bioreactors from 20 to 2000 l total volume. Microbial cultures of Saccharomyces cerevisiae, Pichia pastoris and Streptomyces virginiae were grown in batch and fed-batch culture in both defined and complex media in order to demonstrate the wide dynamic operating range of the instrument. A linear correlation was found between the on-line capacitance measurement and the off-line measurements (optical density, OD620; packed mycelial volume, PMV; biomass concentration X, and colony forming units, CFU ml-1) for biomass concentrations (dry cell weight) up to 30 g l-1 (St. virginiae), 106 g l-1 (S. cerevisiae) and 89 g l-1 (P. pastoris). The on-line capacitance measurement was slightly influenced by variations in agitation speed and strong extraneous radio frequencies. A specific capacitance constant (Cs) was defined for all microbial cells which was dependent on cell viability and cell size. The Cs was easy to calculate using the on-line capacitance measurement and an off-line estimation of biomass concentration. The Biomass Monitor proved suitable for precise on-line monitoring of both homogeneous (uni-cellular) and heterogeneous (mycelial) cultures in bioreactors.
Ecole Supérieure de Biotechnologie de Strasbourg (Cursus commun des Universités du Rhin supérieur), France.
R
R
Fehrenbach
M
M
Comberbach
J O
JO
Pêtre
D001709:Biotechnology / Q000295:instrumentation* / Q000379:methods; D004463:Ecology; D004553:Electric Conductivity; D007700:Kinetics; D010843:Pichia / Q000254:growth & development*; D012441:Saccharomyces cerevisiae / Q000254:growth & development*; D013302:Streptomyces / Q000254:growth & development*