Interaction of media components during bioreactor sterilization: definition and importance of R0

Abstract

Sterilization of bioreactor media, to destroy viability of the indigenous microbial population, is normally accomplished by autoclaving, or heating with pressurized steam. However, simultaneous chemical changes in media can also be expected to result from the high temperatures. A kinetic procedure involving on-line computer calculation of heat input, designated as F0 values, was previously developed to estimate sterility achievement. A similar kinetic procedure, based on a general purpose Arrhenius 'pseudo' rate equation and designated as R0 values, has now been designed to evaluate, and control the effects of temperature and heating time on chemical reactions occurring in the media. Data are presented indicating that R0 may be a useful parameter for reducing variability in culture metabolism and 'scale-up' when these variations result from different nutrient concentrations produced by non-standard heating during media sterilization in stirred bioreactors. © 1989 Society for Industrial Microbiology.