Zygomycota

Sporangia of a Zygomycota fungus.

Zygomycota is a Phylum of the Kingdom Fungi. This phylum's name is derived from the method of sexual reproduction used by its members, which involve the creation of zygosporangia and zygospores. Asexual reproduction is possible, but more difficult, so the former is the preferred way to determine the classification of a Zygomycota. [1] There are approximately 900 known species that fall into this Phylum, which composes approximately one-hundredth of all true fungi. [2]

Identification

Most isolated specimens of Zygomycota do not have zygospores present (due to not currently undergoing sexual reproduction), so generally identification is based on sporangial morphology. [4] Once the fungus matures and establishes itself on a medium, identification is most efficiently done. One particularly common example is Black Bread Mold (Rhizobus stolonifer), which belongs to Zygomycota. [6] Beyond their unique zygospores, Zygomycetes share many charachteristics with their true fungi brethren, such as their chitin walls and hyphae, but their mycelia lack septa. [2]

Reproduction

Members of Aygomycota reproduce both sexually and asexually, with differing life phases based on what type of reproduction is to occur. [5] For the former, gametangial fusion occurs and involves the formation of zygospores. The latter involves sporangia. [2] Besides the pros and cons that natively come with both sexual and asexual reproduction, for members of this phylum, zygospores appear better suited for preserving the fungus during times of hardship, while sporangia seem to be better suited for rapid establishment and colonization. [1] The ability to reproduce sexually is a trait that is uncommon among fungi, although it is not exclusive to Zygomycota. [6]

Zygospores and Sexual Reproduction

Sexual reproduction in Zygomycota is similar to the conjugation process that a microscopic organism such as a protozoan might use. To initiate this form of reproduction, certain hyphae called gametangia form a connection and exchange genetic material in nuclei in the center of the connected area. After it accumulates, septa are created to seal off the cell, meiosis creates chromosomes, and the cell where this has taken place grows thick, resistant walls that eventually disconnects. This site becomes known as a zygosporangium, and when the outer layers wear away (allowing the genetic material to be released if ready), it becomes a zygospore. [3] The gametangia used in this process have different "strains", plus and minus. These strains are morphologically similar but differ physiologically and biochemically. [5]

Impact on Other Organisms

This Phylum includes many parasitic members; insects in particular can be ravaged by Zygomycetes, but many larger animals (including humans) can become diseased by them. [1]