Microbiology: Fungi- yeasts and molds Flashcards

Saccharomyces is the common yeast often used in making wine, beeer and bread.

The term "yeast" simply refer to fungi that grow as single, round cells and don't form hyphae.

Yeast is not a taxonomic group, it's a Description of a body type.

these eukaryotic cells contain a nucleus (stained dark in this image) and a central vacuole.

Hyphae- individual fungal filaments which collectively form a Mycelium.

They are dark in dematiaceous fungi and lack pigment in hyaline (moniliaceous)fungi.

Hyaline- All hyaline hyphae lack pigment- see photo

Hyphae with septa are called septate hyphae.
Septa are cross walls with pores to allow the movement of cytoplasm in hyphae.

Hyphae may be septate, and walls separate adjacent cells, or non septate if walls are absent.

Macrofungi-
Filamentous fungi that produce fleshy reproductive structures-mushrooms, puffballs, and shelf fungi- although the majority of the fungus is filamentous and hidden underground or within decaying matter...
we call them Macrofungi

Various asexual spores may be produced during the life cycle of many fungi. If they form at the ends of hyphae this is what they are.

Other asexual spores which are produced by budding.

produced when a hypha breaks

Non Motile
Absorptive heterotrophs (they don't ingest)
Chitin = cell wall
Spores = reproductive means
Sexual & asexual

Secretes exoenzymes into the environment, then absorbs the digested nutrients.

Most are saphrophytes that decompose dead organic matter but some are parasites of plants, animals or humans.

consumes dead organic matter.

These have both mold and yeast life-cycle stages.

These are tangled mats of hyphae, or many hyphae tangled together.

These are formed at the end of some hyphae and are a resting stage

Formal taxonomic categories are based on the pattern of sexual spore production and the presence of crosswalls inthe hyphae.

terrestrial, have nonseptate hyphae, and produce nonmotile sporangiospores and zygospores

Produce a sac (an ascus) in which the zygote undergoes meiosis to produce haploid ascospores. hyphae are septate

Septate hyphae, and during sexual reproduction produce a basidium that undergoes meiosis to produce four basidiospores attached to its surface.

An unnatural assemblage of fungi in which sexual stages are either unknown or not used in classification. Most of these resemble ascomycetes.

*Called sporangium fungi
* ex: Rhizopus Stolonifer
* non septate
* asexual structure called sporangium- produces sporangiospores
* Sexual spore produced by conjugagtion when (+) hyphae and (-) fused is called zygospore.
* Zygospores can endure harsh environments until conditions improve and new sporangium.

* Called sac fungi
* ex: saccharomyces cerevisiae
* Can reproduce both sexually and asexually
* yeast reproduce asexually by budding
* Asexual spores called conidia
* Ascus (sacs)

* Called club fungi
* ex: mushrooms, puffballs, shelf fungi
* Some used as food, others cause crop damage
* seldom asexual
* Vegetative structures found below ground (hyphae and mycelium)for anchor and absorbing nutrients

Candida albicans Vegetative cells
Note the oval shape and the nuclei

Saccharomyces cerevisiae Unstained

Saccharomyces cerevisiae
note the budding cells (arrows)

Rhizopus sporangiosphores

Rhizopus (nigricans) Zygospore

Perfect example of Rhizopus Zygospores in the middle and at bottom left.

look close there is a sporangium at center top too.

Rhizopus Sporangium

Aspergillus Conidiiospores

Aspergillus Conidiiospores

Penicillium

Penicillium Conidiospores

Rhizopus
* Mold
* Zygomycetes
* Features are sexual and asexual stages
* is a bread mold. certain species cause Zygomycosis

Aspergillus
* Mold
* Ascomycetes
* Features: the fruiting body with chains of conidia arising from one or two rows of philalides attached to a swollen vesicle at the end of an unbranched conidiopore.

* Used in soy sauce, citric acid (causes aspergillosis)

Penicillum
* Mold
* Ascomycetes
* Features: sexual reproduction results in the formation of ascospores, hence we classify in Ascomycetes

* Used to make penicillin. Only one species is pathogenic (P. marneffei) in Asia

Saccharomyces cerevisiae
* Yeast
* Ascomycetes
* One of the budding yeasts, used to make bread, beer, wine, no mycelium, produces a colony like bacteria (
* Not a pathogen)

Candida albicans
* yeast
* Ascomycetes
* Budding yeast, normal part of human flora
* Causes thrush, vulvovaginitis, candidiasis