Conidiobolus coronatus
| Conidiobolus coronatus | |
|---|---|
| Scientific classification | |
| Kingdom: | Fungi |
| Division: | Zygomycota |
| Subdivision: | Entomophthoromycotina |
| Order: | Entomophthorales |
| Family: | Ancylistaceae |
| Genus: | Conidiobolus |
| Species: | C. coronatus |
| Binomial name | |
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Conidiobolus coronatus (Costantin) Batko (1964) |
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| Synonyms | |
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Conidiobolus coronatus is a saprotrophic fungus, first described by Costantin in 1897 as Boudierella coronata. Though this fungus has also been known by the name Entomophthora coronata, the correct name is Conidiobolus coronatus.C. coronatus is classified in the Zygomycota despite that many of its characteristics do not abide by those commonly seen in zygomycetous fungi.C. coronatus is able to infect humans, and animals, and the first human infection with C. coronatus was reported in Jamaica in 1965.
Originally, C. coronatus was considered to be a part of the genus Boudierella, however it was later transferred to the genus Conidiobolus by Saccardo and Sydow. The fungus was also treated in the genus Entomophthora, and the name Entomophthora coronata remains a widely used synonym. Another synonym attributed to C. coronatus is Conidiobolus villosus by G.W. Martin in 1925 due to the characteristic presence of villi.
C. coronatus produces rapidly growing colonies that appear fuzzy and are flat. In their early stages, the colonies are both glabrous and adherent. In terms of colour, young C. coronatus colonies appear creamy gray, however as it ages, the colony adopts a tan to light brown colour. When grown on specific medium (Sabouraud-glucose agar with 0.2% yeast extract or potato dextrose agar (PDA) at 21 °C), C. coronatus colonies can reach approximately 4–5 cm in diameter within 3 days, demonstrating their rapid growth. When the fungus is grown at higher temperatures of about 37 °C, furrow and fold formation can be seen.
C. coronatus reproduces asexually and produces thin-walled hyphae which occur singly or in clusters, with very few septa. At times, the hyphae will demonstrate an eosinophilic halo surrounding their edges, this halo has been termed the Splendore-Hoeppli phenomenon.C. coronatus hyphae can easily be visualized when hematoxylin and eosin staining is performed, however they cannot be visualized via PAS or silver staining. The hyphae have unbranched sporangia, and some of these round sporangia exhibit short extensions, aptly named secondary spores. The single celled round sporangia, as well as the secondary spores, get ejected from the short sporangiophores, and they can travel up to 30mm upon ejection. If the medium the sporangia and spores land on is nutrient-dense, they will germinate and form one or more hyphal tubes, and the fungus will then continue its development and growth.Conidiobolus has three possible developmental pathways: (i) the fungus can remain in reproductive mode and form one or more secondary spores, (ii) the fungus may form a vegetative germ tube or (iii) it may not germinate at all. If the sporangia germinate through the development of a vegetative germ tube, the germ tube will then develop into a mycelium and go on to produce many sporangia and sporangiospores. If the fungus germinates through the formation of secondary spores, these secondary spores will usually be slightly smaller than the parent spores. The secondary spores may also go on to produce many smaller microspores. In young cultures, the C. coronatus spores have a smooth appearance, however as they mature, the spores gradually become covered with short hair like projections called villi. The presence of villi is characteristic of C. coronatus. Growth of the fungus in vivo shows a histologic pattern similar to that seen in other Zygomycota infections.
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