clavulanic acid is produced industrially by fermentation of streptomyces clavuligerus and researches have increased its production by strain improvement, recombinant dna technology, and media composition and growth condition optimization. the main objective of this study was to increase the level of clavulanic acid production from streptomyces clavuligerus (dsm 738), using uv irradiation. after...

conclusions: the hereditary stability analysis of the uv mentioning 45 minutes revealed the uv exposure time for mutants and 3 represented the colony taken from the plate irradiated for 45 minutes mutant showed that the production of avermectin b1b remained constant and no reverse mutation occurred after 15 generations. results: avermectin b1b-hyper-producing mutant, produced using these three ...

Clavulanic acid is produced industrially by fermentation of Streptomyces clavuligerus and researches have increased its production by strain improvement, recombinant DNA technology, and media composition and growth condition optimization. The main objective of this study was to increase the level of clavulanic acid production from Streptomyces clavuligerus (DSM 738), using UV irradiation. After...

Incubation of UV-irradiated plasmid DNA with a protein extract prepared from Escherichia coli cells led to the production of mutations in the cro gene residing on the plasmid. The mutations were detected in a subsequent bioassay step, which involved transformation of an indicator strain with the plasmid DNA that was retrieved from the reaction mixture, followed by plating on lactose/MacConkey p...

Bacteriophage T4 DNA metabolism is largely insulated from that of its host, although some host functions assist in the repair of T4 DNA damage. Environmental factors sometimes affect survival and mutagenesis after ultraviolet (UV) irradiation of T4, and can affect mutagenesis in many organisms. We therefore tested the effect of certain environmental factors and host genetic defects upon spontan...

Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage. Two models have been proposed: "error-free" bypass of deaminated cytosine-containing cyclobutane pyrimidine dimers (CPDs) by DNA polymerase η, and error-pr...

The T4 mutations px, y and 1206 inactivate an error-prone recombination-like repair system, reducing or abolishing mutagenesis by UV irradiation, MMS, and white light irradiation in the presence of the photosensitizer 8MOP. Both px and y increase some spontaneous mutation rates and slightly enhance proflavin mutagenesis; neither mutation affects thymineless or 2AP mutagenesis appreciably, but b...