Medical Mycology - Taxonomic Classiffication of Fungi 2021.pptx

Microbiology

1. Taxonomic Classification of Fungi HTC MULAGO LECTURE SERIES BUGA RUDOLF 11/30/2022 1

2. T axonomy Organizing, classifying and naming of living things Formal system originated by Carl von Linné (1701-1778) Involves identifying and classifying of organisms according to specific criteria Each organism is placed into a classification system T o find similarities and similarities 11/30/2022 2

3. Principles of Classification and Nomenclature Mycological Taxonomy CLASIFICATION ABREVIATION TERMINATION KINGDOM (K.) FUNGI DIVISION (D) MYCOTA Subdivision ( s.D ). MYCOTINA CLASS (Cl.) MYCETES Subclass ( s.Cl .) MYCETIDEAE ORDER (O.) ALES Suborder ( s.O ) INEAE FAMILY (F)/ ( am.) ACEAE Sub. FAMILY ( s.F ). (s.Fam.) OIDEAE TRIBE (T.) EAE GENUS ( g. ) SUBGENUS ( sg. ) SPECIES ( spp .) SUBSPECIES ( ssp..) VARIETY ( var ) RACE (r) ECOTYP ( E ) eco.t 11/30/2022 3

4. Principles of Classification and Nomenclature… Modern Taxonomy Domain - Eukarya Kingdom - Fungi Phylum/Division - mycota Class - mycetes Order - ales Family - aceae Genus ---------- Species ---------- 4

5. P rinciples of classification and Nomenclature Definition of “species” in microbiology Type strains: “Known” and well-characterized pure cultures; can be used as references for the identification of unknowns American Type Culture Collection (ATCC) 11/30/2022 5

6. P rinciples… Species” vs. “Strain” Species: A specific or defined type of organism, defined by similarity with known species. Strain: Genetic variation within a species 11/30/2022 6

7. P rinciples… Nomenclature Scientific name (Systematic Name) Binomial System of Nomenclature Genus name + species name Italicized or underlined genus name is capitalized and may be abbreviated species name is never abbreviated. E.g . Aspergillus fumigatus 11/30/2022 7

8. Classification of fungi Separation of taxa is primarily based on the method of spore production of the perfect or sexual state ( telemorph ) F ive major divisions/phyla of fungi Ascomycota (ascomycetes) Zygomycota ( zygomycetes ) Basidiomycota (basidiomycetes) Chytridiomycota ( Chytrids ) Deuteromycota (Fungi imperfectii ) 11/30/2022 8

9. Classification of fungi… The first four phyla (true sexual groups) P roduce sexual spores (ascospores, zygospores , basidiospores and oospores respectively) All groups of fungi fungi infect humans except Chytridiomycota Deuteromycota (Fungi imperfecti ) are accommodate fungi without a perfect state ( telemorphs ) but represent asexual state (anamorphs) 11/30/2022 9

10. Classification of fungi… G enera in Fungi imperfecti are called ``form genera`` since they are not identified by using sexual characteristics ( zygospores , basidiospores , oospores and ascospores ) Fungi imperfecti are not classified on ‘’evolutionary relationship’’ e.g. Aspergillus fischerianus Members of this group are known or referred by their anamorphic names 11/30/2022 10

11. Classification… Chytridiomycota (Chytridiomycetes / Chytrids) are important carriers of diseases in agriculture and lower cold blooded animals Some genera are classified as Dermateceous because of the presence of melanin in the cell walls of conidia, hyphae or both, resulting in dark coloured fungus Three genera are classified as dermatophytes because they attack hair, nail and skin on living humans Examples ( Epidermophyton, Microsporum and T richophyton ), and Dimorphism is coded at species levels Genera that contain dimorphic species are referred to as moulds e.g. Coccidiodes 11/30/2022 11

12. Classification… Phylum – Zygomycota (Bread or Fin Moulds) Class-Zygomycetes Order- Mucorales (mucors, black bread molds) Family- Mucoraceae ( Absidia, Mucor, Rhizopus ) 11/30/2022 12

13. Classification… 2 . Phylum – Ascomycota (sac fungi/common moulds ). a) Class- Hemiascomycetes or Saccharomycetes Order- Saccharomycetales Family- Saccharomycetaceae ( Candida sp ). b) Class- Pneumocystiodiomycetes Order- Pneumocystidiales Family- Pneumocystidiaceae ( Pneumocystis jirovecii ) 11/30/2022 13

14. Classification … c) Class- Plectomycetes or Eurotiomycetes Order1- Eurotiales Family- Eurotiaceae ( Aspergillus, Penicillium ) Order2- Omygenales Family- Gymnoascaceae Azellomyces ( Blastomyces dermatidis, Histoplasm capsulatum ) Arthroderma ( Microsporum, Trichophyton , Epidermophyton ). Uncinocarpus ( Coccidiodes immitis ) 11/30/2022 14

15. Classification … d) Class- Pyrenomycetes or Sordariomycetes. Order- Ophiostomatales Family- Ophiostomataceae ( Sporothrix schenckii ) 3. Phylum – Basidiomycota (club fungi/mushrooms, toad stools) Class- Ustilagrinomycetes Order- Mallasseziales ( Mallassezia furfur ) 11/30/2022 15

16. Classification … 4 . Pylum- Deuteromycota or Fungi Imperfecti Class- Blastomycetes Order- Cryptococeales Family- Cryptococcaceae Genera ( Candida, Cryptococcus,Malassezia,Pityrosporum, Rhodotorula , Trichosporon ) 11/30/2022 16

17. Classification… b) Class- Hyptomycetes Order- Moniliales Family- Moniliaceae ( Aspergillus, Blastomyces , Coccidiodes , Epidermophyton , Geotricum , Histoplasma , Paracoccidiodes , Penicillium , Sporothrix , Trichophyton , etc.) 11/30/2022 17

18. Ascomycota Ascomycetes all have ascospores borne in asci (sexual stage) Hyphae bear numerous septa Many are yeasts ascomycetes Asexual reproduction is by conidia that always lack motility Sexual reproduction results into ascus formation 11/30/2022 18

19. Ascomycota … Asci are packed together in a cup or flask-shaped ‘ ascocarp ’ Mostly terrestrial, some occur in fresh water or marine habits Occur every where, year round and as minute black dots on rotting wood or on lichen Associated with food spoilage and ergotism Some research tools in genetics and biochemistry 11/30/2022 19

20. Zycomycota Produce zygospores, non motile Have coenocytic hyphae with many haploid nuclei Asexual reproduction is by sporangia or conidia Sexual reproduction produces tough, thick-walled zygotes ( zygospores ) Members are usually terrestrial but rarely encountered in water Grows on moist carbohydrate rich surfaces ( e.g.breads,fruits , vegetables, etc). 11/30/2022 20

21. Zycomycota … Special hyphae (rhizoids) penetrate substrate to absorb nutrients Other hyphae ( stolons ) become erect, arch back into the substratum to form new rhizoids Other hyphae remain erect producing at their tips asexual sporangia filled with black spores giving the mold its characteristics colour 11/30/2022 21

22. Zycomycota … Rhizopus reproduces asexually, unless food becomes scarce then sexual reproduction starts ( + ve and – ve strains) Mating hyphae produce progametangia that matures into gametangia After fusion of the gametangia , the nuclei of the 2 gametes fuse forming zygote, 11/30/2022 22

23. Zygomycota … Zygote develops a thick, rough and black wall and becomes a dormant zygospore Meiosis occur during germination, zygospore splits open and reproduces hypha that bears an asexual sporangium and the cycle continues 11/30/2022 23

24. Basidiomycota Large group of mushrooms and puffballs Characterized posses basidia that are involved in sexual reproduction) and produce basidiospores Basidia are held in fruiting bodies called the basidiocarps Hyphae are septate 11/30/2022 24

25. Basidiomycota … Lack motile spores Many hyphae bear ‘’clamp connections’’ with specialized role in nuclei migration Asexual spores produced as conidia Members are mainly terrestrial.e.g . Amaniota phalloides is toxic. Important Basidiomycete is Cr . neoformans important human pathogens 11/30/2022 25

26. Chytridiomycota / Chytrids Simplest and true fungi Produce asexual and sexual spores in sporangia Asexually produce motile zoospores that bear posterior whiplash flagella Zoospores (swimming cells) escape to the environment 11/30/2022 26

27. Chytridiomycota / Chytrids Zoospores are microscopic and may be singlecelled or small multinucleate mass of a true mycelium Rarely encountered as moulds Terrestrial and aquatic 11/30/2022 27

28. Deuteromycota/Fungi Imperfecti Taxonomic classification is based on sexual reproduction Fungus without sexual phase (perfect stage) is placed within this phylum Molecular systematics places the Deuteromycota among their closest relatives in the Eumycota . Produce asexual conidia 11/30/2022 28

29. Deuteromycota /Fungi Imperfecti … Alternation of reproductive phases: Asexual (anamorph ), Sexual (teleomorph ) and both ( synanamorph ) Most fungi imperfecti are terrestrial Several species are human pathogens, causing athlete’s foot, ring worm and histoplasmosis Some produce antibiotics e.g. Penicillin , Griseofulvin , etc. 11/30/2022 29