Genetically improved strains

Development of Genetically Improved Strains of Bacillus thuringiensis... 

For an industrial biotransformation, it is often necessary to further optimize an appropriate biocatalyst. This includes the elimination of the follow-up enzymes in the wild-type strain by mutations and the improvement of other characteristics by additional mutations and the selection of improved strains. Alternatively, the genetic information for a desired enzyme might be introduced in a host that has many of the preceding characteristics, and that has no enzymes that could modify or degrade the desired product. 

Whether a biocatalyst consists either of an isolate from a natural environment, of a classically improved strain or of a strain improved by various types of genetic engineering, the biocatalyst that is obtained after a screening effort will eventually be applied in a process. In order to obtain sufficient amounts of active biocatalyst, the cells have to be produced by fermentation. 

The stock should be indigenous or acclimatized to the farm or region. Thus, traditional, unimproved breeds and strains are preferred over genetically improved hybrids, raising questions over the appropriate nutrient requirements of such stock. 

Improving Toxicity Screening and Drug Development by Using Genetically Defined Strains... 

Extensive studies in this field including genetic studies, strain improvement by mutation, medium economization and improvement of extraction and purification techniques have led to substantial improvements in process development generally yielding an efficient and economic production. 

From our own analysis of potential risks, ve find it difficult to see how any public institution or private corporation would consider release of genetically modified microbes without incorporating some sort of containment system. First is the problem, perceived or actual, of liability. Secondly, they may find that their product persists too long, interfering with future sales and with introductions of improved strains. Finally, government approval may take an inordinate amount of time reviewing the risk factors of a non-contained system, as compared to one with a proven type of containment. 

Molecular genetic techniques now available hold great potential for improving strains for biological pesticide development. For example, low-virulence strains may be enhanced to improve efficacy. Species difficult to grow or that reproduce poorly in artificial culture may be genetically altered to make them available in large... 

If the current S. cerevisiae strains do not exhibit pronounced strain-specific effects on wine flavor, is it possible to genetically improve them to produce desired aroma components Such improvement could be accomplished by utilizing classical hybridization, protoplast fusion, mutation/selection or genetic engineering techniques (70), presupposing that the characteristic(s) to be selected for is under the control of a single gene (59). 

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