Stability and Degeneration of Microbial Cultures on Repeated Transfer

Abstract

Culture stability and degeneration refer to the ability of a given microbial population to retain desirable morphological or biosynthetic characteristics qualitatively and quantitatively from generation to generation. This chapter discusses the nature and function of various recombination mechanisms encountered in microorganisms. It describes the structural aspects of DNA and RNA in moderate detail since both represent the chemical basis of the genetic material. The chapter also presents specific examples of culture stability and degeneration as observed in fermentation processes of industrial significance, in order to exemplify the problems faced by the investigator, attempting to synthesize and maintain strains with a desired biochemical capability. It is noted that it is very difficult to assign any single process as causative for culture degeneration since several processes can be active at the same time. Also, the relative magnitude of different processes causing degeneration can vary in different organisms. Suppression of the replicating processes is considered the method of choice to prevent degeneration of a particular culture.