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Abstract Corynebacterium glutamicum is a small, non-motile Grampositive commensal bacterium. It has a rod-shaped morphology with swelled ends similar to a club. It does not form spores. The L-glutamate producing microorganism C. glutamicum has an important role in the amino acid fermentation industry. In the last few years, many genetic engineering tools and worldwide analysis methods for this bacterium have been established and successfully used, giving a detailed understanding of its physiology and allowing the progress of effective producing strains. L Tryptophan is considered as neutral amino acid. It is combined in proteins during the procedure of mRNA translation. L Tryptophan is one of the 9 essential amino acids of human which cannot be synthesized internally by him, and need to be given with nutrition. Microbial production is the main method for obtaining tryptophan for commercial use. Typical microorganisms used for tryptophan production are E. coli and C. glutamicum. Tryptophan producing strains of these bacteria have been built by the classical mutagenic procedure or recombinant DNA technology. Mutation is the everlasting modification of the genome of an organism, it occurs due to faults during DNA replication or due to additional types of injury to DNA. Mutagens could be physical, chemical or biological in origin. They may act directly on the DNA, causing direct injury to the DNA, and mainly lead to replication error. Start codon targeted polymorphism (SCoT), is a simple gene targeted DNA marker depend on the short-conserved region in genes. Primers for SCoT marker study were planned from the conserved region surrounding the translation initiation codon ATG. Inter-simple sequence repeats (ISSRs) are sites in the genome lined by microsatellite sequences. PCR amplification of these regions by using a single primer produce multiple amplification products that could.be used as a dominant multi locus marker system in knowing the genetic variation in different organisms. Increasing the production of tryptophan from C. glutamicum i.e genetic improvement was the main target of the study. So, induction of mutation using UV radiation was performed to achieve this goal. The estimation of the produced tryptophan was done by biological assay using E. coli auxotroph for tryptophan. In this work, the final tryptophan yields were 29.4 μg/ml (50% increment), 48.8 μg/ml (138.3% increment), 278.4 μg/ml (1259.4% increment) and 81.6 μg/ml (295% increment) from strains 3, 6, 8 and 10 respectively. The tryptophan yield is remarkably increased especially in strain 8 (298.5 μg/ml), then strain 10 (81.6 μg/ml). Molecular genetics markers used (SCoT and ISSR) showed an ability to differentiate between the two original strains and their mutants by the presence and absence of certain DNA fragment bands, and that showed the genetic change that took place after mutation that lead to increment of tryptophan production by this method.. |