Properties of heterozygous diploids between strains ofPenicillium chrysogenum selected for high penicillin yield

Macdonald, K. D.; Hutchinson, J. M.; Gillett, W. A.

doi:10.1007/bf02046727

Cited by 22 publications

(13 citation statements)

References 12 publications

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“…chrysogenurn indicated that many pairs of markers assort independently and established several linkage groups (Sermonti, 1957;Ball, 1971). In contrast, where divergent industrial strains were involved there was a strong tendency for the markers to retain their parental combinations (Macdonald et al, 1964). This different behaviour is believed to result from chromosomal rearrangements in the divergent strains which prevent reassociation at haploidization between the linkage groups concerned (Macdonald, 1968 ;Ball, 1971).…”

Section: B)mentioning

confidence: 99%

“…This different behaviour is believed to result from chromosomal rearrangements in the divergent strains which prevent reassociation at haploidization between the linkage groups concerned (Macdonald, 1968 ;Ball, 1971). Since the divergent strains were all derived from the same ancestor (Macdonald et al, 1964), the chromosomal rearrangements must have been induced during the mutation and selection programmes. The presence of at least certain types of chromosomal rearrangements in industrial strains of P .…”

Section: B)mentioning

confidence: 99%

“…number of titre-increasing mutations involved and their interaction (Macdonald et al, 1964(Macdonald et al, , 1965. This phenomenon of parental genome segregation probably resulted from differences in chromosome structure produced by the repeated mutagenic treatments to which the parent strains had been subjected (Macdonald, 1968).…”

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confidence: 99%

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Genetics of Penicillin Titre in Lines of Aspergillus nidulans Selected through Recurrent Mutagenesis

Simpson¹,

Caten²

1980

Microbiology

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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 unselected 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 111 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.

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Section: B)mentioning

confidence: 99%

Section: B)mentioning

confidence: 99%

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Genetics of Penicillin Titre in Lines of Aspergillus nidulans Selected through Recurrent Mutagenesis

Simpson¹,

Caten²

1980

Microbiology

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“…Subsequent detailed studies of penicillin production in P. chrysogemm using parasexual analyses (Sermonti, I 959 ; Macdonald, Hutchinson & Gillett, 1963a, b, c, 1964, 1965 cast doubts on the practical application of hybridization to titre improvement and these reservations do not appear to have changed significantly in recent years (Alikhanian, 1970). Genetic analysis of high-titre industrial strains is impeded by the low frequency of recovery of recombinants among segregants from diploids (Macdonald et al 1965) and by frequent somatic instability (Elander, 1967). Both these difficulties may be attributed to chromosomal aberrations induced by the recurrent mutagenic treatments used in titre improvement (Macdonald, 1968 ;Kafer, 1969;Azevedo & Roper, 1970).…”

Section: Introductionmentioning

confidence: 99%

Hybridization and Selection for Increased Penicillin Titre in Wild-type Isolates of Aspergillus nidulans

Merrick

1975

Journal of General Microbiology

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SUM MARYRepeated hybridization and selection among wild-type isolates produced strains of Aspergillus nidulans with increased penicillin titre. Four independent selection lines were established, each originating from a sexual cross between two different heterokaryon-incompatible wild-type isolates. In each generation, two selected high-titre sister strains were crossed to produce the next generation. An initial increase in titre was obtained in each line, but after four or five generations of selection the genetic variation was considerably reduced and the rate of response to selection had decreased. From a base population of wild-type isolates with a mean titre of 8.6 unitslml the progeny mean titre was raised to between 16 and 20 units/ml in each line. The gradual nature of the response suggests that a number of genes determine penicillin titre in the wild-type isolates used. The gene action throughout the selection programme was predominantly additive.

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“…nidulans has also been found with major mutations (Ditchburn et al, 1976) and with natural variation (Merrick, 1975 b). Deductions concerning the extent of allelism between divergent strains of P. chrysogenum from the results of parasexual crosses are complicated firstly by variation in yield between independent diploids from the same original parents (Macdonald et al, 1965), and secondly by the parental genome segregation observed in these crosses (Macdonald et al, 1964(Macdonald et al, , 1965.…”

Section: Discussionmentioning

confidence: 99%

Selection for Increased Penicillin Titre Following Hybridization of Divergent Lines of Aspergillus nidulans

Simpson

Caten

1981

Microbiology

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Properties of heterozygous diploids between strains ofPenicillium chrysogenum selected for high penicillin yield

Cited by 22 publications

References 12 publications

Genetics of Penicillin Titre in Lines of Aspergillus nidulans Selected through Recurrent Mutagenesis

Genetics of Penicillin Titre in Lines of Aspergillus nidulans Selected through Recurrent Mutagenesis

Hybridization and Selection for Increased Penicillin Titre in Wild-type Isolates of Aspergillus nidulans

Selection for Increased Penicillin Titre Following Hybridization of Divergent Lines of Aspergillus nidulans

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