Genetic analyses of mutations for increased penicillin titre were carried out on two strains of Aspergillus nidulans isolated after independent programmes of recurrent mutation and selection, similar to those used industrially for strain improvement. Both selected strains were stable in terms of colony morphology and penicillin titre. Backcrosses to the un-selected ancestor indicated that the increased yield of each strain was due to an induced polygenic system with both additive and non-additive gene action. The titre-increasing mutations in one strain (A6-9) were recessive to their wild-type alleles, while those in the other (B6-27) were either semi-dominant or showed ambidirectional dominance. The diploid between A6-9 and B6-27 had a titre less than either component haploid, suggesting that the mutations in the two strains involved different genes. Strain B6-27 carried a translocation between chromosomes III and VII which had been induced during the selection programme. This investigation complements previous work on the genetics of penicillin production in A. nidulans and Penicillium chrysogenum and the results are directly relevant to industrial strain improvement by hybridization of divergent strains.
AlikhanianS.I., KamenevaS.V.1961; Hybridisation of highly active strains of Penicillium chrysogenum. Scientific Reports of the Istituto Superiore di Sanità 1:454–463
BainbridgeB.W., RoperJ.A.1966; Observations on the effects of a chromosome duplication in Aspergillus nidulans. Journal of General Microbiology 42:417–424
BallC.1973a; Improvement of penicillin productivity in Penicillium chrysogenum by recombination. In Genetics of Industrial MicroorganismsII pp. 227–237 Edited by VaněkZ., HoštálekZ., CudlínJ. Prague: Academia.;
BallC.1978; Genetics in the development of the penicillin process. In Antibiotics and Other Secondary Metabolites pp. 165–176 Edited by HütterR., LeisingerT., NúeschJ., WehrliW. London: Academic Press.;
BallC., AzevedoJ.L.1976; Genetic instability in parasexual fungi. In Second International Symposium on the Genetics of Industrial Microorganisms pp. 243–251 Edited by MacdonaldK.D. London: Academic Press.;
CatenC.E.1979; Quantitative genetic variation in fungi. In Quantitative Genetic Variation pp. 35–59 Edited by ThompsonJ.N.JrThodayJ.M. New York: Academic Press.;
CatenC.E., JinksJ.L.1976; Quantitative genetics. In Second International Symposium on the Genetics of Industrial Microorganisms pp. 93–111 Edited by MacdonaldK.D. London: Academic Press.;
DitchburnP., HoltG., MacdonaldK.D.1976; The genetic location of mutations increasing penicillin yield in Aspergillus nidulans. In Second International Symposium on the Genetics of Industrial Microorganisms pp. 213–227 Edited by MacdonaldK.D. London: Academic Press.;
ElanderR.P.1967; Enhanced penicillin biosynthesis in mutant and recombinant strains of Penicillium chrysogenum. Abhandlungen der DeutschenAkademie der Wissenschaftenzu Berlin, Klasse für Medizin 2:403–423
ElanderR.P., EspenshadeM.A.1976; The role of microbiA1 genetics in industrial Microbiology. In Industrial Microbiology pp. 192–256 Edited by MillerB.M., LitskyW. New York: McGraw-Hill.;
ElanderR.P., EspenshadeM.A., PathakS.G., PanC.H.1973; The use of parasexual genetics in an industrial strain selection programme with Penicillium chrysogenum. In Genetics of Industrial MicroorganismsII pp. 239–253 Edited by VaněkZ., HoštálekZ., CudlínJ. Prague: Academia.;
HamlynP.F., BallC.1979; Recombination studies with Cephalosporium acremonium. In Genetics of Industrial Microorganisms pp. 185–191 Edited by SebekO.K., LaskinA.I. Washington, D.C.: American Society for Microbiology.;
HoltG., MacdonaldK.D.1968b; Isolation of strains with increased penicillin yield after hybridisation in Aspergillus nidulans. Nature; London: 219636–637
HoltG., EdwardsG.F.ST.L, MacdonaldK.D.1976; The genetics of mutants impaired in the biosynthesis of penicillin. In Second International Symposium on the Genetics of Industrial Microorganisms pp. 199–211 Edited by MacdonaldK.D. London: Academic Press.;
MacdonaldK.D.1968; The persistence of parental genome segregation in Penicillium chrysogenum after nitrogen mustard treatment. Mutation Research 5:302–305
MacdonaldK.D., HutchinsonJ.M., GillettW.A.1963a; Heterokaryon studies and the genetic control of penicillin and chrysogenin production in Penicillium chrysogenum. Journal of General Microbiology 33:375–383
MacdonaldK.D., HutchinsonJ.M., GillettW.A.1963b; Formation and segregation of heterozygous diploids between a wild-type strain and derivatives of high penicillin yield in Penicillium chrysogenum. Journal of General Microbiology 33:385–394
MacdonaldK.D., HutchinsonJ.M., GillettW.A.1964; Properties of heterozygous diploids between strains of Penicillium chrysogenum selected for high penicillin yield. Antonie van Leeuwenhoek 30:209–224
MccullyK.S., ForbesE.1965; The use of j?-fluorophenylalanine with “Master strain”? of Aspergillus nidulans for assigning genes to linkage groups. Genetical Research 6:352–359
MerrickM.J.1975a; Hybridization and selection for increased penicillin titre in wild-type isolates of Aspergillus nidulans. Journal of General Microbiology 91:278–286
MerrickM.J.1975b; The inheritance of penicillin titre in crosses between lines of Aspergillus nidulans selected for increased productivity. Journal of General Microbiology 91:287–294
MerrickM.J., CatenC.E.1975; The inheritance of penicillin titre in wild-type isolates of Aspergillus nidulans. Journal of Genral Microbiology 86:283–293
RoperJ.A.1973; Mitotic recombination and mitotic non-conformity in fungi. In Genetics of Industrial MicroorganismsII pp. 81–88 Edited by VaněkZ., HoštálekZ., CudlínJ. Prague: Academia.;
SermontiG.1961; The parasexual cycle in Penicillium chrysogenum and its application to the production of penicillin. Scientific Reports of the Istituto Superiore di Sanità 1:449–454
SimpsonI.N., CatenC.E.1979a; Induced quantitative variation for penicillin titre in clonal populations of Aspergillus nidulans. Journal of General Microbiology 110:1–12
SimpsonI.N., CatenC.E.1979b; Recurrent mutation and selection for increased penicillin titre in Aspergillus nidulans. Journal of General Microbiology 113:209–217
UpshallA., KäferE.1974; Detection and identification of translocations by increased specific non-disjunction in Aspergillus nidulans. Genetics 76:19–31