Synthesis of deactoxycephalosporin C by a mutant of Cephalosporium acremonium

Isolation of deacetoxycephalosporin C from fermentation broths of Penicillium chrysogenum transformants: construction of a new fungal biosynthetic pathway

Deacetoxycephalosporin C (DAOC), a precursor of cephalosporins excreted by Cephalosporium and Streptomyces species, has been produced in Penicillium chrysogenum transformed with DNA containing a hybrid penicillin N expandase gene (cefEh) and a hybrid isopenicillin N epimerase gene (cefDh). DAOC from a P. chrysogenum transformant was identified by ultraviolet light (UV), high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) and mass spectrum analyses. P. chrysogenum transformed with DNA containing cefEh without cefDh did not produce DAOC. Untransformed P. chrysogenum produced penicillin V (phenoxymethylpenicillin) but not DAOC. Transformants also produced penicillin V but, in general, less than untransformed P. chrysogenum. The cefEh and cefDh genes were constructed by replacing the open reading frame (ORF) of cloned P. chrysogenum pcbC and penDE genes with the ORF of the Streptomyces clavuligerus expandase gene, cefE, and the ORF of the Streptomyces lipmanii epimerase gene, cefD, respectively. Analyses of representative transformants suggested that production of DAOC occurred via cefEh and cefDh genes stably integrated in the P. chrysogenum genome. DNA from untransformed P. chrysogenum did not hybridize to cefE or cefD gene probes.

Spectrum and characteristics of the virus-inhibitory action of two isoquinoline derivatives

Conditions for the accurate measure of glutamic dehydrogenase (GDH) from Cephalosporium acremonium were determined. K_m values for α-ketoglutarate and ammonium ion were 7 and 15 mM, respectively. The half-saturation for reduced nicotinamide adenine dinucleotide phosphate was 5 μM. Reduced nicotinamide adenine dinucleotide did not serve as a cofactor for the enzyme. The specific activity of GDH was measured in six mutants of C. acremonium which varied in their ability to synthesize cephalosporin C. The mutants represented two separately derived lines, A and B. The four mutants in line B were characterized by a derepression of the GDH upon entry into stationary phase. The two mutants in line A were characterized by repressed levels of GDH during the same period. Both lines exhibited high GDH activity early in their fermentations, but activity decreased during the period of active cell growth. Cytochrome c concentrations followed the same pattern as total soluble intracellular protein. Line A mutants were low in cephalosporin C productivity and line B encompassed low, intermediate, and high productivity mutants. The relative frequency of yield improvements in line A and B indicate that the altered regulation pattern for GDH in line B may have removed a nitrogen limitation for cephalosporin C synthesis.