metal ions are the main impurities of water and media ingredients used in fermentation processes. in this research, the effect of ca+2, co+2, cu+2, fe+2, mg+2, mn+2 and zn+2 as chloride and sulfate salts was studied on the clavulanic acid production and streptomyces clavuligerus growth. all chloride salts had negative effect on clavulanic acid production and no clavulanic acid was produced in t...

Clavulanic acid (CA) is a potent inhibitor of β-lactamases, enzymes that are responsible for the hydrolysis of β-lactam antibiotics. It is a secondary metabolite produced by the filamentous aerobic bacterium Streptomyces clavuligerus in submerged cultivations. In the present work clavulanic acid production in batch, fed-batch and continuous bioreactors was studied with the objective of increasi...

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...

CcaR is a positive-acting transcriptional regulator involved in cephamycin C and clavulanic acid biosynthesis in Streptomyces clavuligerus. Previous sequence analyses of the ccaR gene revealed two possible start codons, an ATG, and a GTG located in-frame 18 bp downstream of the ATG. To determine the true start codon, ccaR was expressed, either from the GTG or ATG codon, in Escherichia coli. A p...

Streptomyces clavuligerus ATCC 27064 and S. clavuligerus ΔccaR::tsr cultures were grown in asparagine-starch medium, and samples were taken in the exponential and stationary growth phases. Transcriptomic analysis showed that the expression of 186 genes was altered in the ccaR-deleted mutant. These genes belong to the cephamycin C gene cluster, clavulanic acid gene cluster, clavams, holomycin, d...

Cephamycin C production was blocked in wild-type cultures of the clavulanic acid-producing organism Streptomyces clavuligerus by targeted disruption of the gene (lat) encoding lysine epsilon-aminotransferase. Specific production of clavulanic acid increased in the lat mutants derived from the wild-type strain by 2- to 2.5-fold. Similar beneficial effects on clavulanic acid production were noted...