title: Optimization of casein-based semisynthetic medium for growing of toxigenic Corinebacterium diphtheriae in a fermenter.
abstract: Diphtheria toxin is produced by growing Corinebacterium diphtheriae either in a semisynthetic casein-based medium or in the Pope-Lingood meat extract based medium. The World Health Organization advises the use of the semisynthetic one, as it has important advantages. Data on the composition of casein-based media and their ability to support high toxin production are not freely available. Important factors affecting toxin production during C. diphtheriae cultivation are the pH of the culture medium and the concentration of casein hydrolysate and of Fe2+. We established that the optimal pH for toxin production is 7.2. The highest yield of toxin was obtained using a casein hydrolysate concentration of 35.0 g/L and a Fe2+ concentration of 0.05-0.41 microg/mL. Under these conditions, diphtheria toxin with higher purity and yield compared with the batches obtained using the meat-based medium of Pope-Lingood was produced.
authors.affiliation: Stefan Angelov Institute of Microbiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria. tchorban@microbio.bas.bg
authors.forename: Andrey I
authors.initials: AI
authors.lastname: Tchorbanov
authors.forename: Jordan D
authors.initials: JD
authors.lastname: Dimitrov
authors.forename: Tchavdar L
authors.initials: TL
authors.lastname: Vassilev
mesh_terms: D002364:Caseins / Q000737:chemistry*; D003353:Corynebacterium diphtheriae / Q000254:growth & development* / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry*; D004167:Diphtheria Toxin / Q000096:biosynthesis* / Q000302:isolation & purification; D005285:Fermentation; D005296:Ferrous Compounds; D006863:Hydrogen-Ion Concentration
chemical_list: D002364:Caseins; D003470:Culture Media; D004167:Diphtheria Toxin; D005296:Ferrous Compounds; C475729:casein hydrolysate