Aspergillus can reproduce sexually or asexually, like all species in the phylum Ascomycota. Most of the time, they reproduce asexually, while others, like Aspergillus Niger, are known to reproduce sexually.
Because of the high oxygen tension, Aspergillus species frequently develop as moulds on the surface of a substrate. They are highly aerobic and can be found in practically all oxygen-rich situations. Aspergillus species can grow in or on various plants and trees and are frequently found in starchy foods (like potatoes and bread). Aspergillus species, such as A. niger and A. fumigatus, rapidly colonise structures, preferring warm, wet, or humid regions like restrooms and the area around window frames.
Table of Contents
Classification of Aspergillus
The Aspergillus species appear as greenish, smoky patches (conidial stage) along with Rhizopus, Mucor and Penicillium on moist bread.
|
Kingdom |
Fungi |
|---|---|
|
Division |
Ascomycota |
|
Class |
Eurotiomycetes |
|
Order |
Eurotiales |
|
Family |
Trichocomaceae |
|
Genus |
Aspergillus |
Life Cycle of Aspergillus
The most widespread aspergillus species is A. niger. They undergo vegetative, sexual or asexual reproduction.
- Conidial spores are produced by Aspergillus niger during asexual reproduction.
- The life cycle begins with the dispersal of the conidia onto a substrate with an optimum temperature of at least 25 to 40 °C.
- Conidia then develop into vegetative cells by germination.
- The cells transform into hyphal mycelium and branches dichotomously to form aerial hyphae.
- The aerial hyphae develop into conidiophores, which enlarge at the apex to produce the conidiophore’s vesicle.
- The primary sterigmata, called the phialides, develop from the vesicles.
- The secondary sterigmata are formed by the sterigmata, which begin to produce conidial spores.
- On top of the phialides, the spores are organised in columns (multiple rows).
A haploid phase and a diploid phase alternate in the life cycle of a sexually reproducing fungi. Nuclear fusion signals the end of the haploid phase and the start of the diploid phase, which is when the zygote is formed. Meiosis (reduced division) begins the haploid stage, producing the gametes, and restores the haploid amount of chromosomes.
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