Zycomycetes Identification
description
Transcript of Zycomycetes Identification
Typical Zygomycete Colonies
Apophysomyces elegans Rhizopus oryzae
Note the completely filled Petri dish.
Species of Absidia, Rhizopus, Rhizomucorare o3en thermotolerant or thermophilic l thermotolerant and thermophilic species are known as pathogenic or can be poten:ally pathogenic
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Genus idenAficaAon may be difficult, IdenAfying an isolate as a zygomycete will usually suffice because treatment with anA‐fungal anAbioAcs is oHen empirical
• Major differences between genera – Presence or absence of root like structures (rhizoids)
– LocaAon of rhizoids (directly below the sporangiophore(s) or distant from sporangiophore
– Branching or non‐branching conidiophore – Present or absence of apophysis – Shape and arrangement of columnella and apophysis – Shape of sporangia – Shape of sporangiospores – Smooth or echinulate sporangiospores
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Rhizopus
At 25oC, wooly greyish brown color, fill plate in 2 days. Broad, aseptate unbranched hyphae, either single or tuHs of brown sporangiophores (conidiophores) arising from stolons opposite well‐developed rhizoids (root‐like structures). Sporangiophores end in sporangia with a round columella (vesicle, enlarged at the apex), producing round to oval sporangiospores or sexual spores. Sporangia are globose, with apophysis and columella. Sporangiospores are angular subglobose, and ellipAcal.
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Rhizopus oryzae: most common zygomycetes. Causes angioinvasion, thrombosis, infarcAon and necrosis of the involved Assues. Sinuses and
rhiocerebral structures are two common involved sites.
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Mucor species
Young sporangium Old sporangium Globose sporangium filled with sporangiospores [branched ( racemoseor, sympodial) or unbranched, well developed globose columnella, rhizoids not produced. The max
temp for growth in Mucor is less than 37oC, but Rhizomucor can grow at 54oC.
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Absidia species
Pyriform sporangium, conical columnella, funnel shaped apophysis, branched sporangiophores Absidia produces rhizoids (rare) on stolons but not opposite the conidiophore e.g. A. cornmbifera:
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Rhizomucor
• Rhizomucor grow very rapidly. Wooly colony white iniAally and turned gray to black over Ame, reverse is white to pale.Sporangiophores are irregularly branched with brown and round sporangia at their apices. Apophysis absent, columellae are prominent and spherical to pyriform in shape.
• Rhizomucor is dis:nguished from Mucor by the presence of stolons and poorly developed rhizoids at the base of the sporangiophores and by the thermophilic nature of its 3 species: R. miehei, R. pusillus and R. tauricus. Temperature growth range: minimum 20‐27C; opAmum 35‐55C; maximum 55‐60C
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Syncephalastrum
Rapid grow, filling plate in 3 days, wooly and gray colored. Borad aseptate or sparingly septate , hyaline hyphae. sporangiophores branched and short with swol‐ len Ap. On this swollen Ap, chains of round spores, enclosed in a finger like tubular sporangia called merosporangia. (iniAate isolaAon may resemble Asp. Niger, examine for merosporangia containing spores and not phialides) 2 species, widespread with a preference for tropical and subtropical regions • Merosporangium and merospores Merosporangia with spores in rows vesicle
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Syncephalastrum racemosum
• Rarely known as pathogen in humans. Isolated from environmental sources worldwide.
• 5 days at r.t. produced low‐growing or tall erect mycelia that cover the whole plate. Surface white to gray and black and pale brown on reverse
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Key Features for Differen6a6on from Other Members of Zygomycetes
Structure Differen6a6on
Pyriform sporangium Absidia (+); Mucor (‐), Rhizomucor (‐), Rhizopus (‐)
Septum below the sporangium Absidia (+); Apophysomyces* (‐)
Well‐developed apophysis Absidia (+), Mucor (‐), Rhizomucor (‐), Rhizopus (‐)
Sporangiophores arising between rhizoids and not opposite them
Absidia (+); Rhizopus (‐)
Abundant sporulaAon on rouAne mycological media
Absidia (+); Apophysomyces (‐)
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