UV mutagenesis

Mutations in either recA or lexA can abolish the SOS-response and eliminate both W-reactivation and W-mutagenesis. These mutations also eliminate the mutability of the bacteria by UV-irradiation (16) The observation that UV mutagenesis depended on the SOS-response established that mutations were not inevitable outcomes of DNA damage and that DNA damage required processing by cellular mechanisms in order for mutations to be recovered. What specific processes regulated by the SOS-response are responsible for mutagenesis ... 

Although it is counterintuitive, chemical or UV mutagenesis appears to be no more effective than reliance on spontaneous mutations to produce the desired phenotypes. The key elements for success in isolating mutants with novel capabilities, especially those capabilities that require multiple mutations, appear to be (1) large populations, (2) intense selection, and (3) prolonged periods of selection that may last up to several weeks. 

Optimum Color Range for UV Mutagenesis Repair (online paper)... 

Chae, S.-K., and Kafer, E. (1993). uvs-1 mutants defective in UV mutagenesis define a fourth epistatic group of uvs genes in Aspergillus. Curr. Genet. 24, 67-74. 

Bridges, B. A., and Woodgate, R. (1984). Mutagenic repair in Escherichia coli, X. The umuC gene product may be required for replication past pyrimidine dimers but not for the coding error in UV mutagenesis. Mol. Gen. Genet. 196, 364-366. 

Steinborn, G. (1978). Uvm mutants of Escherichia cofi K12 deficient in UV mutagenesis. I. Isolation of uvm mutants and their phenotypical characterization in DNA repair and mutagenesis. Mol. Gen. Genet. 165, 87-93. 

Brotcorne-Lannoye, A., and Maenhaut-Michel, G. (1986). Role of RecA protein in untargeted UV mutagenesis of bacteriophage lambda Eyidence for the requirement for the dinB gene. Proc. Natl. Acad. Sci. USA 83, 3904-3908. 

Dutreix, M., Moreau, P. L., Bailone, A., Galibert, F., Battista, J. R., Walker, G. C., and Devoret, R. (1989). New recA mutations that dissociate the various RecA protein activities in Escherichia coli provide evidence for an additional role for RecA protein in UV mutagenesis. / Bad. 171, 2415-2423. 

Several strategies, including metabolic engineering, have been applied to improve the optical purity of LA optimizing enantioselective biosynthesis. For instance, a Lc. lactis mutant strain obtained by UV mutagenesis was able to produce d-LA from molasses and hydrolyzed sugarcane with 73% yield [308], while a recombinant strain of Lb. plantarum NCIMB 8826 produced... 

Ugwu CU, Tokiwa Y, Aoyagi H, Uchiyama H, Tanaka H. UV mutagenesis of Cupriavidus necator for extracellular production of (R)-3-hydroxybutyric a.cid.JAppl Microbiol 2008 105 236-42. 

Rossman TG (1981) Enhancement of UV-mutagenesis by low concentrations of arsenite in E. coli. Mutat Res 91 207-211... 

S. cerevisiae sake K6 was the first industrial strain isolated for SAM production. By UV mutagenesis, a mutant auxotroph strain K6-1 was isolated, and it displayed comparable growth rates and SAM yield to those of K6. Subsequent over-expression of sam2 in K6-1 evidently resulted in improved SAM productivity. Expression of ERCl, which endowed the strain with tolerance to ethionine and was responsible for MAT activity, led to accumulation of considerably more SAM (Shiomi et al. 1991). Recently, SAM2 and ERCl were co-expressed in strain ESI, leading to yield of 2 g/L SAM (Lee et al. 2010). 

Ugwu CU, Tokiwa Y, Aoyagi H, Uchiyama H, Tanaka H (2008) UV mutagenesis of Cupriavidus necator for extraceliuiar production of (R)-3-hydroxybutyric add. J Appl Microbiol 105 236-242 Valentin HE, Steinbiichel A (1994) Application of enzymatically synthesized short-chain-length hydroxy fatty acid coenzyme A thioesters for assay of polyhydroxyalkanoic add biosynthesis. Appl Microbiol Biotechnol 40 699-709... 

Mutagenesis and screening have been used in a variety of organisms to obtain mutants with improved ethanol production ability. For example, a mutant of P. stipitis was obtained by UV mutagenesis, which exhibited increased ethanol fermentation ability from xylose [114]. This mutant was able to produce 43gl ethanol from 114gl xylose, a 38% increase relative to the original strain. 

Ahmad, I., Day, J.P., MacDonald, M.V., Ingram, D.S., 1991. Haploid culture and UV mutagenesis in rapid-cycling Brassica napus for the generation of resistance to chlorsulfuron and Altemaria brassicolia. Ann. BoL 67, 521-525. 

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