Advances in selection markers and their bio-safety in applications of transformed microorganisms

Abstract:

Selection markers are one of the basic parts in a genetic transformation system in molecular biotechnology. The functions of selectable marker genes are selecting transformants from non-transformed cells and maintaining a stress for selective growth of recombinant population. Drug-resistant genes are the most commonly used selectable marker genes, usually as a part of Escherichia coli vectors and other shuttle-vectors. It is considered bio-safe to use engineered strains carrying drug-resistant genes in fermentations of enzymes or organic compounds, because the fermentor systems are closely controlled and the products are to be refined. But the application of drug-resistant genes should be prohibited when genetic modification of the strains to be used for food/feed fermentation, environment remediation, plant bio-protection, and so on. Therefore, the development of bio-safety selection markers has been a key issue in the application of molecular biotechnology. This paper reviews the types and properties of currently used selection markers, and introduces the novelty and advantages of selection marker GFAT, a gene coding for a glucosamine synthetase. Selection marker GFAT will be useful in natural environments because no need to add or delete any compounds for generating selection stress.