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Microbiology > Fungal Taxonomy > Flashcards

Fungal Taxonomy Flashcards

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1
Q

What Taxonomy do fungi belong to?

A

Kingdom - Fungi

BUT

Clade - Opisthokonta, belonging to Eukaryota superkingdom.

Phylum is -mycota

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2
Q

What are Higher vs lower fungi?

A

Higher fungi - two phyla include Basidiomycota and Ascomycota.
= Filamentous, Septated hyphae.
More numerous than Lower fungi.

Ascomycota - sac fungi, with spores in ball sack.

Basidiomycota - spores in club-like cell.

LOWER fungi - no septated hyphae, so coenocytic hyphae = multinucleated filament.
E.g. Chytriodomycota = flagellated, but simplest and most primitive example.
Other lower fungi phyla have evolved to lose flagella.

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3
Q

How many phyla are there in Fungi?

A

All end with Mycota suffix.

There are 6:
Ascomycota
Basidiomycota
Glomales
Zygomycota
Chytridiomycota
Recent addition of Microsporidia.

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4
Q

What are Microsporidia?

A

Recently added fungal phylum.

Eukaryotic, Unicellular, Obligate intracellular parasites.

Have loste mitochondria, so fully depend on host.

No flagellum, no plasta either.

Infect vertebrates and arthropods.

E.g Fish paraiste icythosporidium hoferi.

Microsporidiosis - infect as opportunists immunocompromised humans.

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5
Q

Characteristics of Microsporidia?

A

No mitochondria, no flagellum, no plaste.

Intracellular obligate parasites.

Microsporidia produce resistant chitinous-walled spore with a polar spiral tube

The polar tube permits the Sporoplasm (cyto. of spore) to inoculate host cell and inject nucleus into host cytoplasm.

Once paraistized, mitosis of spore and production of multinucleated plasmas called syncytium plasmodia, then production of spores via sporulation.

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6
Q

What is the Chytriodiomycota phylum?

A

A lower fungi - coenocytic fungi.
The most primitive and smallest sized phylum.

Flagellated zoospores.

Usually aquatic and saprophytic but can be parasites.
- Potato wart agent.

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7
Q

What is Glomeromycota phylum?

A

Lower fungi.
Coenocytic hyphae, with non-flagellated spores.

Very important industrially as form Arbuscular Endomycorrihizae.
= Symbiotic parasites with plant roots.

As endomycorrhizae.
(80% of terristrial vascular plants have symbiosis with this phylum).

Fungus enters through cell wall with its hyphae.
The hyphae is enveloped by perifungal membrane of host PM. This permits nutrient exchange. Central vacuole reduces and hyphae occupies of lumen.
But increases SA for absorption of water/minerals.

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8
Q

What is Zygomycota phylum?

A

Lower fungi, with coenocytic hyphae.
Non-flagellated spores.

Mostly saprophytes.
Zygomycota are GRAS - generally recognised as safe species.

  • Cultivated industrially as tofu or bioreactor metabolites.

BUT can be parasitic to insects.

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9
Q

How are Higher fungi discriminated from each other?

A

Both Basidio and Asccomycota have septated hyphae.

Based on the type of meiospores - spores of sexual reproduction.

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10
Q

What is the process of fungal sexual reproduction?

A

Starts off with 2 haploid hyphae = n x n

Plasmogamy = fusion of cytoplasms of the 2 haploid hyphae, produces a single dikaryotic hyphae = n + n

Caryogamy - fusion of both nuclei of apical hyphae - producing a diploid nucleus in the apical cells = 2n.

Meiosis = producing 4 haploid meiospores - n

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11
Q

What is Plasmogamy and Caryogamy?

A

Plasmogamy = fusion of cytoplasms of the 2 haploid hyphae, produces a single dikaryotic hyphae = n + n

Caryogamy - fusion of both nuclei of apical hyphae - producing a diploid nucleus in the apical cells = 2n.

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12
Q

What are homokaryons and dikaryons?

A

Homokaryons are homokaryotic hyphae possessing one type of haploid nuclei (n chromosomes)

Dikaryons possess two types of haploid nuclei as a result of plasmogamy before caryogamy occurs - (n+n)

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13
Q

How does the location of meiospores differ between Basidio and Ascomycota?

A

The apical cells undergoing sexual reproduction will fuse via plasmogamy, undergo caryogamy and then meiosis to produce meiospores.

In ascomycota, the meiospores (Ascospores) are located in the ascus (apical cell) where caryogamy and meiosis have occurred…. So apical cell contains the meiospores together in 1 cell.
= Spores in a sac

In Basidiomycota, the Basidiospores migrate outside the basdium (Apical cell) after caryogamy and meiosis.
= Spores on the club like snail antennae.

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14
Q

Are fungi segregated by forms of reproduction?

A

Anamorphic strains = no sexual reproduction.
E.G Aspergillus

Teleomorphic strains = both sexual and asexual reproduction.
E.G Gibberella

Suppressed phylum was Deuteromycota without known sexual reproduction

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15
Q

What are examples of filamentous ascomycota?

A

Penicillium species:

E.G
Penicillium chrysogenum makes Penicillin industrially.

Penicillium roqueforti on Roquefort blue cheese.

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16
Q

How was the yield of penicillin increased?

A

Strain improvement to Penicillium chrysogenum via Metabolic Rewiring:

Inducing random mutagenesis in order to increase the production of a secondary metabolite, in this case penicillin.
- It is secondary because it is not essential for cell growth.

17
Q

What ascomycota species can infect humans?

What are other uses of Ascomycota?

A

Aspergillus species can infect immunocompromised individuals.
Especially Aspergillus Fumigatus = Opportunistic infection.

Use as biological models:

Podospora Anserina used to study aging.
Aspergillus Niger used to ferment Sake.

Beauveria bassiana = TO produce biosoft/beauvericin as an insecticide and antibacterial for biological control.

18
Q

How can Ascomycota serve to infect plants and insects?

A

Phytopathogens = Fusarium, Botrytis, Claviceps.

Fusarium causes corn rot.

Botrytis causes straweberry mould.
(Needed to produce sweet wines in Noble rot)

Entomopathogens = insect infection.

Cordiceps sinensis = Filamentous ascomycota which infects caterpillars.
When inside caterpillar, spores germinate, kills caterpillar, caterpillar mummified and produces its fruiting body.

19
Q

Macroscopic fruiting bodies of Ascomycota?

A

Pezizes = fruiting body in a cup shape

Morel - Cone shaped but with holes - in each hole is the ascus/sac containing the ascospores.

Black truffles - The fruiting body of an Ectomycorrhizael fungus in Oak Trees.
= produce volatile aromatic compounds and many different secondary metabolites, antibacterial, herbicidal.

20
Q

How do the fruiting bodies of Basidiomycota and Ascomycota compare?

A

In basidiomycota, Sexual spores are exposed outside of the mother cell (Baside) - The Basidiospores on outside

In ascomycota, withinin the Ascus (mother cell), there are 8 ascospores.

21
Q

What are two examples of phytopathogenic Basidiomycota?

A

Pucciniomycota - Wheat Rust - as produces asexual spores in orange colour.

Ustomycetes - corn smut, grey mass of hyphae in corn.

22
Q

What fungi causes the majority of macroscopic fruiting bodies?

A

Macromycetes - Produce visible fruiting bodies, large macroscopic fruiting bodies.

Most of the fruiting body/sporophore is composed of N+N hyphae (Where cells have undergone plasmogamy, where cytoplasm of male and female cells fuse).
These subapical hyphae form the protective body of the fruiting body.
BUT ONLY THE APICAL CELLS PRODUCE THE SPORES

23
Q

What phyla has most industrially grown mushrooms?

A

Basidiomycota

Mostly grown on compost, straw, sawdust.

Agaricus bisporus = Champignons de Paris.

24
Q

Poisonous mushrooms?

A

Alpha-Amanitin = causes majority of poisonous cases of mushrooms.

Produces 10g of carpophores.
= Death by RNA pol II inhibition (stops transcription).
= Non-ribosomal cyclic peptide.

Psilocybe = produces psilocybin = hallucinogenic.

25
Q

How can fungi spread?

A

Vegetative propagation - Fragmentation of vegetative body/thallus = NO MITOSIS other than normal growth.

Asexual multiplication - abdunant mitoses, where all mitospores are clones of mother cell.

Sexual multiplication - Fertilisation/ fusion of 2 haploid individuals with different sexual types.
= Genetic diversity and appearance of new individuals.

26
Q

Explain vegetative propagation?

A

Fragmentation of the thallus.
Mitosis not involved - only when involved with growth.

Thallus fragmentation occurs with Thallospores.

Examples:
Chlamydospores
Slerotium
Claviceps Purpurea

27
Q

What are chlamydospores an example of?

Sclerotium?

A

Chlamydospores have a thickened, resistant cell wall which protects from adverse conditions.

Dictyspores are multicellular spores with a network like appearance.

Sclerotium are a compact mass of hyphae with thickened cell walls and nutrient reserve = surviving the winter, to allow for growth in spring.

E.G in Claviceps purpurea.
Rye ergot - sclerotia break off and remain dormant until spring.

Sclerotia rich in secondary metabolites, including ergotamine (Used as vasoconstrictor for headaches)
And caused ergotism in Middle Ages.
(An example of mycotoxin)

Also produce Bromocryptine - used for Parkioson’s as dopaminergic.

Ergometrine - vasoconstrictrive to prevent uterus bleeding after delivery.

28
Q

What is the process of asexual reproduction?

A

Conidiogenesis - The conidiophore is differentiated from branched articles.

Conidiophore connects to the Conidia/Mitospores.

Conidiophore is specialised hyphael structure that supports development of the Conidia (Structure of the Mitospores)

Mitospores are genetically identical, form from multiple mitoses.

Penicillium species - witch broom.
Aspergilli species.
Fusarium - Conidia directly produced from hyphae.

The identical mitospores are mostly responsible for epidemic expansion of plant pathogens.

Conidia form on branched devices - having free conidiophores or conidiophores in protective structure.

29
Q

Where can conidiophores be found?

A

Conidia form on branched devices - having free conidiophores or conidiophores in protective structure.

Pycnidia - black-rot of vine have protective structure containing conidiophores.

Aspergilli have free conidiophores supporting the conidia.

30
Q

What are the first steps of sexual reproduction?

A

1 = Plasmogamy
Fusion of 2 homokaryons forming a dikaryon.

(Homokaryon possesses 1 type of haploid nucleus = n)

Dikaryon possess 2 types of haploid nuclei (N+N). (BEFORE CARYOGAMY, as separated in time)
So plasmogamy can occur, with growth of a dikaryotic colony before karyogamy occurs in the apical cells of fruiting bodies…

Anastomosis loops

31
Q

What is an anastomosis loop?

A

Mechanism by which fungi maintain a dikaryotic state after plasmogamy.

The two nuclei synchronously divide = so has 4 nuclei.

Nucleus migrates in retrograde manner via a lateral branch t form an anastomosis loop
A septum is installed, to make a sub-apical article.
Then other nucleus migrates to sub-apical article.
= Now two articles, each dikaryotic.

32
Q

What is the diversity of plasmogamy?

A

Can occur between many different cell types

Between gametes

Between gamete producing organs.

Between common cells of the thallus.

33
Q

what are Homothalism and Heterothalism?

A

Self-fertilisation

Heterothallism occurs when there is presence of genes of sexual incompatibility, which prevents self-fertilisataion, in addition to differentiation of M and F reproductive organs.
= So requires 2 compatible partners to make sexual spores.
Yeast!!!! Saccharomyces cerevisiae is heterothallism bipolar a/a

34
Q

What is involved in ascomycota sexual reproduction?

A

The production of the ascocarp - the fruiting body.

Plasmogamy of two compatible mating types.
Male structure transfers nuclei into female structure, to produce dikaryotic state.

After Plasmogamy, dikaryotic hyphae grow and develop into specialised fruiting body (ascocarp).
(Apothecium if open cup-shaped) - via Anostamosis loops.

Then karyogamy - apical cells of dikaryotic hyphae undergo nuclear fusion to form a single diploid nucleus (in the ascus).

Meiosis - to form 4 haploid nuclei.
Additional mitosis to form 8 haploid nuclei.
Ascospore formation (balls in sac), with 8 ascospores per ascus.

Ascus releases the 8 ascospores. In favourable coniditons, ascospore germinate to form new fungal hyphae.

35
Q

What are the different sexual organs of ascomycota?

A

Free ascus - the ascus is not surrounded by a protective structure.

Perithecium, within a hole.
Cleistothecium - within a protective ball = for conservation during winter
Apothecium - open cup shaped.

Microbiology (5 decks)

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