Patent GB-788118-A (GB)
Title: Improvements in the production of mutants of the genus penicillium
Inventor: AYTOUN ROBERT SINCLAIR CHADWIC
IPC: C12N15/01
Filed: 1955-05-16
Abstract: Griseofulvin is isolated from a fermentation broth obtained by culturing a mutant strain of a Griseofulvin-producing organism said strain having high griseofulvin productivity and being obtained from a parent strain of a griseofulvinproducing organism of the genus Penicillium, e.g. P. patulum Baiser Thom. C. M. 1. 39, 809 (NRRL 989), which has been cultured on or in a medium capable of supporting its growth until sporulation occurs, the whole or a substantial part of the assimilable sulphur source present in the medium being in the form of the radioactive sulphur isotope of mass number 35.  The sulphur source is present in the form S35-sulphate.  In the example, the medium contains sodium nitrate, potassium dihydrogen phosphate, magnesium chloride, ferric chloride, sucrose, agar and water, has a pH of 6.8 to 7.2 and, after the addition of S35 sulphate and inoculation with the parent organism, is incubated at 24 DEG  C. for 6 to 8 days.  Putative mutant spores formed during the sporulation are separated, isolated, cultivated separately to form colonies which are tested for griseofulvin activity by small scale fermentations carried out on a standard nutrient medium under suitable conditions in comparison with a control fermentation using the parent strain, followed by assay for griseofulvin of a cyclohexane or butyl acetate extract of the fermentation broth. A primary screening takes place using a nitro-chalk/brown sugar medium and a secondary screening with a cornsteep liquor/lactose medium.  An aqueous medium containing C.S.L. solids, lactose, potassium chloride, potassium dihydrogen phosphate and limestone is used for the large-scale production of griseofulvin from the selected mutant and recovery of the antibiotic is by solvent extraction.  Specification 784,618 is referred to.ALSO:A griscofulvin-producing-organism of the genus Penicillium having high griscofulvin productivity, is obtained as a mutant of a parent strain of a griscofulvin-producing organism which has been cultured on or in a nutrient medium capable of supporting its growth until sporulation occurs, the whole or a substantial part of the assimilable sulphur source present in the medium being in the form of the radioactive sulphur isotope of mass number 35. The sulphur source is present in the form of S35-sulphate. In the example, the medium contains sodium nitrate, potassium dihydrogen phosphate, magnesium chloride, ferric chloride, sucrose, agar and water, has a pH of 6.8 to 7.2 and, after the addition of S35 sulphate and inoculation with the parent organism, is incubated at 24 DEG  C. for 6 to 8 days. Putative mutant spores formed during the sporulation are separated, isolated, cultivated separately to form colonies which are tested for griscofulvin activity by small scale fermentations carried out on a standard nutrient medium under suitable conditions in comparison with a control fermentation using the parent strain, followed by assay for griscofulvin of the fermentation broth.  The nutrient medium used for the primary screening contains nitro-chalk, brown sugar, potassium chloride, potassium dihydrogen phosphate, magnesium sulphate and water, that for the secondary screening contains corn steep liquor, lactose, potassium chloride, potassium dihydrogen phosphate, limestone and water.  A preferred parent strain is Penicillium Patulum Bainier Thom. C.M.I. 39,809 (NRRL 989).  Specification 784,618, [Group IV (b)], is referred to.