BIOSYNTHESIS OF CEPHALOSPORIN C AND ITS RELATION TO PENICILLIN FORMATION*

Study on genetic engineering of Acremonium chrysogenum, the cephalosporin C producer

Acremonium chrysogenum is an important filamentous fungus which produces cephalosporin C in industry. This review summarized the study on genetic engineering of Acremonium chrysogenum, including biosynthesis and regulation for fermentation of cephalosporin C, molecular techniques, molecular breeding and transcriptomics of Acremonium chrysogenum. We believe with all the techniques available and full genomic sequence, the industrial strain of Acremonium chrysogenum can be genetically modified to better serve the pharmaceutical industry.

Regulation of cephalosporin synthesis in Cephalosporium acremonium by phosphate and glucose

The regulation of cephalosporin synthesis in Cephalosporium acremonium was studied in a simple chemically-defined medium with glucose as the carbon source. Antibiotic synthesis depended on the phosphate content of the medium. At phosphate concentrations above 2.75 mM maximum antibiotic titres were not reached while glucose uptake and growth rates were increased. Phosphate exerted its effect indirectly by regulating the rate of glucose consumption. The negative effect of high phosphate concentrations could be overcome completely by controlling the sugar supply in fed-batch and chemostat experiments. High actual concentrations of phosphate or of glucose alone had no direct negative effect on antibiotic synthesis.

Detection of a cephalosporin C acetyl esterase in the carbamate cephalosporin antibiotic-producing culture, Streptomyces clavuligerus

The possible role of a cephalosporin C acetyl esterase in the formation of the beta-lactam antibiotic A16886A, 7-(5-amino-5-carboxyvaleramido)-3-carbamoyloxy-methyl-3-cephem-4-carboxylic acid, by Streptomyces clavuligerus was studied. Addition of dl-valine-(14)C-1 to a fermentation of Cephalosporium acremonium gave cephalosporin C-(14)C-9 (I). The formation of deacetylcephalosporin C-(14)C-9 from I occurred at a greater rate in broths of S. clavuligerus than in the broths of C. acremonium, or in the autoclaved broths of S. clavuligerus. Diisopropylfluorophosphate partially inhibited the deacetylation of I in S. clavuligerus broth. An intracellular cephalosporin C esterase in S. clavuligerus could not be demonstrated. Although A16886A has been chemically synthesized from deacetylcephalosporin C, this reaction could not be demonstrated with S. clavuligerus.