Molecular BioTechnology by Bernard R. ,Glick, et al.
Biotechnology research is dedicated to maximizing the overall efficiency of each of these steps and to finding microorganisms that make products that are useful in the preparation of foods, food supplements, and drugs. During the 1960s and 1970s, this research focused on upstream processing, bioreactor design, and downstream processing. These studies led to enhanced bioinstrumentation for monitoring and controlling the fermentation process and to efficient large - scale growth facilities that increased the yields of various products. The biotransformation component of the overall process was the most difficult phase to manipulate. Commodity production by naturally occurring microbial strains on a large scale was often considerably less than optimal. Initial efforts to enhance product yields focused on creating variants (mutants) by using chemical mutagens or ultraviolet radiation to induce changes in the genetic constitution of existing strains. However, the level of improvement that could be achieved in this way was usually limited biologically. If a mutated strain, for example, synthesized too much of a compound, other metabolic functions often were impaired, thereby causing the strain’s growth during large-scale fermentation to be less than desired. Despite this constraint, the traditional “induced mutagenesis and selection” strategies of strain improvement were extremely successful for a number of processes, such as the production of antibiotics. The traditional genetic improvement regimens were tedious, timeconsuming, and costly because of the large numbers of colonies that had to be selected, screened, and tested. Moreover, the best result that could be expected with this approach was the improvement of an existing inherited property of a strain rather than the expansion of its genetic capabilities.
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