News Update on Aspergillus Nidulans Research: Dec – 2019

Aspergillus nidulans

Aspergillus nidulans may be a sexually reproducing member of the Aspergillaceae (Raper and Fennell, 1965). The history of genetic investigations of this mold dates from 1945, when Pontecorvo began to search for an organism suitable for a genetic approach to “certain problems of the spacial organisation of the cell” (Pontecorvo et al., 1953). These problems amounted to an effort to define the gene and its reference to cell me-tabolism. the explanations for the selection of A. nidulans also because the story of the first development of genetical studies are fully given in Pontecorvo et al. (1953). Briefly, the benefits of this fungus include the very fact that it’s a haploid eukaryote which rapidly forms colonies on simple media and may therefore be treated as a microorganism. [1]

The Genetics of Aspergillus nidulans

This discusses the lifecycle, the methods of culture, the isolation of mutants, the formal genetics, the identification of loci, and therefore the diploids and mitotic recombination of Aspergillus nidulans (A. nidulans). It also presents various methods of genetic analysis, like heterokaryosis, crossing, recombinant selection from random samples of ascosporesa, and perithecium analysis and relative heterothallism. As in most other filamentous fungi during which amphimixis occurs, A. nidulans (Eidam) Winter, an ascomycete shows a vegetative cycle side-by-side with a sexual cycle. On germination, an uninucleate haploid vegetative spore (conidium) produces colorless septate hyphae with multinucleate cells. The sexual cycle is concentrated in specialized organs, the fruiting bodies (cleistothecia or perithecia). [2]

Transformation of Aspergillus nidulans by using a trpC plasmid

We constructed a chimeric plasmid carrying an entire copy of the trifunctional trpC gene from the Ascomycete fungus Aspergillus nidulans. This plasmid, designated pHY201, replicates in Escherichia coli, where it confers resistance to ampicillin and chloramphenicol and complements trpC mutants lacking phosphoribosylanthranilate isomerase activity. We used pHY201 to rework an A. nidulans trpC- strain to trpC+ at frequencies of greater than 20 stable transformants per microgram of DNA. Southern blot analysis of DNA from transformants showed that pHY201 DNA had integrated into the A. nidulans chromosomes during a majority of cases. Most of the mixing events seemed to occur at the location of the trpC- allele of the recipient strain. In several instances, we succeeded in recovering pHY201, or derivatives thereof, from A. nidulans transformants by restriction nuclease digestion of chromosomal DNA, ligation, and transformation of E. coli. [3]

Sequencing of Aspergillus nidulans and comparative analysis with A. fumigatus and A. oryzae

The aspergilli comprise a various group of filamentous fungi spanning over 200 million years of evolution. Here we report the genome sequence of the model organism Aspergillus nidulans, and a comparative study with Aspergillus fumigatus, a significant human pathogen, and Aspergillus oryzae, utilized in the assembly of sake, miso and soy. Our analysis of genome structure provided a quantitative evaluation of forces driving long-term eukaryotic genome evolution. It also led to an experimentally validated model of mating-type locus evolution, suggesting the potential for amphimixis during a. fumigatus and A. oryzae. [4]

Production of Fat and Sterol by Aspergillus nidulans in Submerged Fermentation

The efficiency of fat and sterol production by Aspergillus nidulans was evaluated. The fungus was grown in media containing various carbon and nitrogen sources. Some agricultural waste materials namely, corn cob, rice husk and potato peels were also used as sole carbon sources for fat and sterol production. Sodium acetate was added into culture media at various concentrations. After a 72 h incubation, mycelia obtained from culture media were assayed for fat and sterol contents. Among the only carbon sources used for fat production, the very best yield of 48.63 mg/100 mL broth was achieved with mannitol after 72 h incubation. Carboxyl methyl cellulose was the poorest carbohydrate for fat production. The agricultural waste materials greatly improved fat production by Aspergillus nidulans. Levels of 44.62, 43.99 and 43.1 mg/100 mL broth were achieved with corn cob, rice husk and potato peels after 72 h incubation. [5]

Reference

[1] Clutterbuck, A.J., 1974. Aspergillus nidulans. In Bacteria, Bacteriophages, and Fungi (pp. 447-510). Springer, Boston, MA. (Web Link)

[2] Pontecorvo, G., Roper, J.A., Chemmons, L.M., MacDonald, K.D. and Bufton, A.W.J., 1953. The genetics of Aspergillus nidulans. In Advances in genetics (Vol. 5, pp. 141-238). Academic Press. (Web Link)

[3] Yelton, M.M., Hamer, J.E. and Timberlake, W.E., 1984. Transformation of Aspergillus nidulans by using a trpC plasmid. Proceedings of the National Academy of Sciences, 81(5), (Web Link)

[4] Sequencing of Aspergillus nidulans and comparative analysis with A. fumigatus and A. oryzae
James E. Galagan, Sarah E. Calvo, […]Bruce W. Birren
Nature volume 438, (Web Link)

[5] Nwokoro, O., H. Ekwem, O. and Oyeagu, U. (2017) “Production of Fat and Sterol by Aspergillus nidulans in Submerged Fermentation”, Chemical Science International Journal, 20(2), (Web Link)

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