Aspergillus niger

From MicrobeWiki, the student-edited microbiology resource

A Microbial Biorealm page on the genus Aspergillus niger

Classification

Higher order taxa

Cellular organisms; Eukaryota; Fungi/Metazoa group; Fungi; Dikarya; Ascomycota; Pezizomycotina; Eurotiomycetes; Eurotiomycetidae; Eurotiales; Trichocomaceae; mitosporic Trichocomaceae; Aspergillus

Species

NCBI: Taxonomy

Aspergillus niger

Description and significance

Aspergillus niger is a haploid filamentous fungi and is a very essential microorganism. In addition to producing extracellular enzymes and citric acid, A. niger is also used for waste management and biotransformations and is found in common mesophilic environments such as decaying vegetation or soil and plants. (2)

Genome sequencing of A. niger is important because of its involvement in producing citric acid industrial enzymes, such as amylases, proteases, and lipases. Other properties of this species include pathogens that cause the spoilage of food and production of secondary metabolites that are toxic. Analyzing the genome of A. niger is also important because of its economic impact, which is $45 billion on the U.S. economy. Understanding this economic importance as well as the effects it makes on the environment makes the genome sequencing of A. niger essential to biological applications.(4, 5)

A. niger was isolated from the plant Welwitschia mirabilis in Namibia and Angola, a plant estimated to be about 3000 years old. A. niger is easily isolated from common thing such as dust, paint, and soil. Commonly in labs, A. niger is isolated via chemostat cultures which can test positively or negatively for the fungi. (3, 6)

Genome structure

A. niger have a total genome size that ranges from 35.5 to 38.5 Mb and is composed of about 13,000 genes. Of these genes, about 8000 to 8500 genes have functional assignments. In addition, about 14,000 open reading frames (ORF) were identified in the genome which could potentially encode a protein. The DNA sequence of A. niger consists of approximately 33.9 million base pairs. The possible function of 6500 genes could be established which is only about 45% of its total gene count.(7)

Chromosomes separated into four separate bands range from 3.5 to 6.6 Mb. The sequence that was obtained could be arranged into 19 separate supercontigs that correspond to eight linear chromosomes.(7)

Treating A. niger with recombinant DNA allows spheroplasts to take up some recombinant DNA. Recombinant DNA has the properties of being both linear and circular and is also used as a selectable marker (since A. niger does not have a programmed selectable marker) which has an antibiotic resistance to transformants. The selectable marker is known as the ornithine carbamoyl transferase gene (Arg B. sup +) and encodes a product that can be assayed. (8)

The recombinant DNA contains a replicon which allows for replication in a bacterial host. The recombinant DNA consists of a plasmid vectors pDG1 (ATCC 53005) and pDG3 (ATCC 53006). Transformation of these vectors includes removing the cell wall enzymatically, adding DNA to the spheroplasts, and incubating.(8)

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology and Pathology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.


Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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References

(1) NCBI: Aspergillus niger, Accessed August 23, 2007, <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=380704&lvl=3&p=mapview&p=has_linkout&p=blast_url&p=genome_blast&lin=f&keep=1&srchmode=1&unlock>

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by Kyle Choi student of Rachel Larsen