Culture media penicillin production

The discovery that addition of side-chain precursors to the culture medium favoured production of the penicillin that had incorporated this side-chain allowed the production of a whole range of novel penicillins. Although around 100 such structures were prepared, only one had more desirable properties than penicillin G, and this was christened penicillin V or phe-noxymethylpenicillin. Although this compound was not as potent as penicillin G, it was much more stable to acid (in the stomach), and so could be administered by mouth rather than requiring injection like penicillin G. This was a major advantage for patients, and penicillin V rapidly became the antibiotic of choice for GPs. 

Figure 6.4 Stylised representation of changing parameters and penicillin production in cultures of Penldlllum notatum, grown as a surface culture on Czapek-Dox medium (adapted from Hockenhull DJ-D "Production of Antibiotics by Fermentation in Essays in Applied Microbiology edited by Norris J R Richmond M H 1981. John Wiley Sons Ltd Chichester).

Over 30 penicillins have been isolated from fermentation mixtures. Some of these occur naturally others have been biusynthc.sizcd by altering the culture medium to provide certain precursors that may be incorporated as acyl groups. Commercial production of biosynthetic peniciliins today depends chielly on various strains of Pcnicillium notatum and P. chrysogenum. In recent years, many more penicillins have been prepared semisynthetically, and undoubtedly, many mure will be added to the list in attempts to find superior products. 

The agricultural industry contributed, through its fermentation facilities and com steep liquor used for the medium of culture, to penicillin development. The production of penicillin increased by more than 10-fold. In fact, by 1944, there was sufficient penicillin to treat all of the severe battle wounds incurred on D-day at Normandy. Also, diseases like syphilis and gonorrhea could suddenly be treated more easily than with earlier treatments. 

Harold Raistrick had succeeded in growing Fleming s mould on a simple culture medium based upon glucose and some mineral salts, but had experienced severe difficulties in isolating the penicillin produced. These problems, both chemical and bacteriological, would not be solved for a further decade. Raistrick did help to identify the mould as Penicillium notatum (rather than P. glaucum) with the assistance of Charles Thom of the US Department of Agriculture (who was to play a major role in the scaleup of penicillin production). 

Media basal RPMI 1640 medium requires supplementation with sodium pyruvate, L-glutamine, and penicillin/streptomycin before use. The supplements are supplied as concentrates of 50X or 100X, and the appropriate amounts should be added. Standard tissue culture media for hybridoma production contain 5%, 10%, or 15% fetal bovine serum (FBS see Note 6). Sufficient quantities should be prepared in advance and a sterility check should be performed on them prior to use. 

Penicillin had been originally produced in surface culture, but titers were very low. Submerged culture soon became the method of choice. By the use of strain improvement and medium modifications, such as the use of corn steep liquor as additive, the yield of penicillin was increased by 100-fold in just a few years. Much of the understanding of the physiology of P. chrysogenum, in relation to penicUlin production, was achieved by Professor Marvin Johnson and his students at the University of Wisconsin. Further clinical successes were demonstrated in both England and the United States, and finally in 1943, penicillin was used to treat those wounded in battle. 

Most A. are produced industrially from microbial cultures (see Industrial microbiology) highly productive strains of microorganisms are used for this purpose, and such strains are maintained in culture collections. Chemical synthesis of A. is also used to a small extent. As far as possible, nutrient media for industrial microbial A. production are prepared from readily available, cheap raw materials, e. g. various sugars, starch, soybean millings, corn steep liquor. The yield of penicillin G can be increased by adding phe-nylacetic acid to the medium as a precursor. As is ty-... 

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