Industrial fermentations with (unstable) recombinant cultures

Abstract

Recombinant DNA technology is yielding organisms with virtually a complete range of genetic stability, i.e. from organisms that appear to be entirely stable over the course of many fermentations to those that are so unstable that their half-life as novel species may be appreciably less than a conventional fermentation time. As such, a novel time-dependent mixed culture community is created, containing at a minimum the original recombinant microbe and a second strain, which may be denoted as a revertant in some partial or full sense. These two strains will differ in one or more important characteristics such as (desired) product formation rates, substrate utiliza­ tion abilities, morphology, biomass growth rates and oxygen demand. In this paper, I consider batch and continuous cultivation, and I use some plausible biological rate forms to explore implications in fermentor behaviour and product formation occa­ sioned by the existence of this particular form of ‘mixed culture’.