A hybrid modeling technique is proposed to make models during the development phase of a fed-batch bioprocess. A limited amount of data is available and experimental data are therefore combined with a priori information about the mass balances and the chemical reaction network inside the cell (the metabolic network). This information highly constraints the model, and only a few degrees of freed...

objective: the clavulanic acid regulatory gene (clar) is in the clavulanic acid biosynthetic gene cluster that encodes clar. this protein is a putative regulator of the late steps of clavulanic acid biosynthesis. the aim of this research is the molecular cloning of clar, isolated from the iranian strain of streptomyces clavuligerus (s. clavuligerus). materials and methods: in this experimental ...

The biosynthesis of cephalosporins involving a thiozolidine ring expansion is catalyzed by deacetoxycephalosporin C synthase (DAOCS). In this study, three DAOCS isozymes were cloned and expressed as active enzymes together with Streptomyces jumonjinensis DAOCS that was newly isolated and partially characterized. The enzymes showed excellent substrate conversion for penicillin G, phenethicillin,...

Cell-free extracts prepared by sonication of Streptomyces clavuligerus cyclized 6-(L-aaminoadipyl)-L-cysteinyl-D-valine (ACV) into a penicillin-type antibiotic. The antibacterial spectrum of this antibiotic suggested it was a mixture of isopenicillin N and penicillin N indicating that both cyclization and racemase activities were present. Cyclization activity was optimal in extracts prepared fr...

A gene (bla) encoding a beta-lactamase is present in the cephamycin gene cluster of Streptomyces clavuligerus, the strain producing clavulanic acid and a beta-lactamase inhibitory protein. The bla gene is located 5.1 kb downstream from and in the opposite orientation to cefE, encoding the deacetoxycephalosporin C synthase. The bla gene encodes a 332-residue protein (Mr, 35,218), similar to othe...

OBJECTIVE The clavulanic acid regulatory gene (claR) is in the clavulanic acid biosynthetic gene cluster that encodes ClaR. This protein is a putative regulator of the late steps of clavulanic acid biosynthesis. The aim of this research is the molecular cloning of claR, isolated from the Iranian strain of Streptomyces clavuligerus (S. clavuligerus). MATERIALS AND METHODS In this experimental ...

In the presence of S-adenosylmethionine, 2-oxoglutarate, Fe2+ and a reducing agent, cell-free extracts of Streptomyces clavuligerus convert cephalosporin C and 0carbamoyldeacetylcephalosporin C into 7a-methoxy derivatives. No synthesis of a 7a-methoxy derivative of deacetylcephalosporin C was detected in the system used, and the 7a-methoxy derivative of deacetoxycephalosporin C was produced onl...