Isolation of auxotrophic mutants of Aspergillus niger by filtration enrichment and lytic enzymes

1992 ◽  
Vol 21 (2) ◽  
pp. 117-120 ◽  
Author(s):  
C. J. Bos ◽  
A. J. M. Debets ◽  
H. Nachtegaal ◽  
S. M. Slakhorst ◽  
K. Swart
Keyword(s):  
Aspergillus Niger ◽  
Lytic Enzymes ◽  
Auxotrophic Mutants ◽  
Filtration Enrichment

Tryptophan auxotrophic mutants in Aspergillus niger: Inactivation of the trpC gene by cotransformation mutagenesis

1989 ◽  
Vol 219 (1-2) ◽  
pp. 282-288 ◽  
Author(s):  
Theo Goosen ◽  
Frank van Engelenburg ◽  
Fons Debets ◽  
Klaas Swart ◽  
Kees Bos ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Auxotrophic Mutants ◽  
Trpc Gene

Improved production of citric acid by a diploid strain of Aspergillus niger

1978 ◽  
Vol 24 (5) ◽  
pp. 622-625 ◽  
Author(s):  
Arati Das ◽  
Ponty Roy
Keyword(s):  
Citric Acid ◽  
Aspergillus Niger ◽  
Uv Radiation ◽  
Diploid Strain ◽  
Auxotrophic Mutants ◽  
Successful Adaptation

Aspergillus niger strain CGU 87 was treated with UV radiation and some auxotrophic mutants were obtained. These mutants were less productive than CGU 87, which produced an average of 7.4% citric acid. All possible crosses in pair wise combinations were carried out between these auxotrophs, and three heterokaryons were synthesised. Finally, one heterozygous diploid was isolated from each of them. These heterokaryons and diploids showed improved productivity when compared with their component parents, but except in one diploid D5, all others produced less citric acid than CGU 87. The yield of D5 exceeded that of CGU 87 by 1.2 times and it produced 9% citric acid. This is a significant improvement and the increased productivity seems to be the result of successful adaptation of D5 to its fermentation environment.

scholarly journals Filtration enrichment method for isolation of auxotrophic mutants of Trichoderma harzianum rifai

1999 ◽  
Vol 30 (1) ◽  
pp. 43-46
Author(s):  
Ana Maria R. Cassiolato ◽  
Itamar Soares de Melo
Keyword(s):  
Growth Rate ◽  
Trichoderma Harzianum ◽  
Genetic Research ◽  
Wild Type ◽  
Enrichment Method ◽  
Isolation Technique ◽  
Auxotrophic Mutants ◽  
Enrichment Technique ◽  
Filtration Enrichment ◽  
Similar Growth

The isolation of genetic markers, like drug resistance and auxotrophy, is a laborious but important step in genetic research. The isolation of auxotrophic mutants of Trichoderma harzianum using the filtration enrichment technique was more effective than using the total isolation technique. Most of 12 auxotrophic mutants exhibited similar growth rate and higher sporulation when compared with the wild type, but only two mutants (TWS-410 and TW5-523) could grow in 500µg/L of benomyl.

Isolation of protoplasts from Aspergillus nidulans conidiospores

1981 ◽  
Vol 27 (4) ◽  
pp. 400-407 ◽  
Author(s):  
C. J. Bos ◽  
S. M. Slakhorst
Keyword(s):  
Cell Wall ◽  
Aspergillus Niger ◽  
Aspergillus Nidulans ◽  
Minimal Medium ◽  
Isolation Procedure ◽  
Lytic Enzymes ◽  
Uniform Size ◽  
Protoplast Suspension ◽  
Recombination Experiments

Protoplasts were prepared from conidiospores of Aspergillus nidulans. The mononucleated conidia gave protoplasts of a uniform size, approximately 5-μm diameter, depending on the strain and the stabilizing medium used. Conidia were preincubated with 2-deoxy-D-glucose in a minimal medium at 37 °C for 3 h. The swollen conidia were collected, resuspended in a buffer containing 0.4 M (NH4)2SO4 as stabilizer, and incubated with Oerskovia lytic enzymes at 30 °C for 3 or 4 h. Approximately 80% of the conidia were converted into protoplasts. The protoplasts were separated from cell wall fragments and intact conidia by centrifugation over 30% sucrose. This isolation procedure gives a suspension of mononucleated or binucleated protoplasts suitable for recombination experiments and other studies for which a homogenous protoplast suspension is required. The procedure was also successful for Aspergillus niger.

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