Fungal diversity and relationships

Fungal Diversity

The Kingdom Fungi (Eumycota) has multiple phyla including the following:

1. Basidiomycota

2. Ascomycota.

How do fungi metabolize?

They are heterotrophs that decompose organic matter (saprotrophs)

Basidiomycota

Example: Agaricus bisporus (common mushroom)

How are bacteria classified?

using 16S rRNA sequencing.

Fungal classification

ITS1 is the region between 18S and 5.8S rRNA.

• we can tell phyla apart from the ITS1

Fungal Nutrition

fungi are heterotrophs with absorptive nutrition, they secrete enzymes to break down material and absorb nutrients

• due to this they are called saprotrophs

Role in Nutrient Cycling

Fungi convert organic matter to inorganic molecules.

• as well Breakdown of dead/decaying material supports ecosystems.

fungi role in gut microbiome

are present in the gut microbiome, but their role is unclear.

Industrial Uses of Fungal Enzymes

• Fungi secrete enzymes that can be used commercially.

• Used in detergents (e.g., removing grass stains).

Fungal Cell Wall

made up of

1. Glucans

2. Chitin

3. inner membrane

4. outter membrane

5. sterols

Inner cell wall

Made up of chitin and branched B-1,3

Chitin

rigid polymer only found in fungus

Outter cell wall

Very variable we can see

1. in yeasts → its comprised of mannan. and mannoproteins

2. B-1,6-glucan in some cases

Sterol specific to fungi

Ergosterol

Distinctive traits in fungi

1. Hyphae

2. Mycelium

3. Fruiting bodies

Hyphea

most fungi grow as extended multinucleiate cellular filaments called hyphae

• Septate hyphae: Have cross-walls separating individual cells.

• Non-septate (coenocytic) hyphae: No cross-walls; multinucleate.

• Pseudohyphae: Chains of elongated yeast cells that remain attached.

• dont need to memorize!

Mycelium

a structure of different hyphae branching, that forms a colony

• Spore germination leads to hyphal growth, forming a mycelium.

  

they can branch to form mushrooms

Fruting bodies

Mycelia can differentiate into fruiting bodies that produce and release spores.

• Example: Mushrooms are fruiting bodies of some fungi.

Microfungi

mostly invisibile to naked eye

• ex) yeast, mould

Macrofungi

produce easily visible fruiting body

• ex) mushrooms

Do all fungi produce spores?

Yes, asexually or sexually

• except yeast onyl forms sexual spores

Distinctive features in asexual reproduction

The lighter region represents the mycelium that hasn't developed any fruiting structures yet, located at the outer edge (peripheral zone). As it forms the fruiting body, the color will change. Once the orange drops, the spores will detach and disperse.

• exponential growth is limited to the periphera growth zone

Distinctive features in sexual production

Example) Ascomyota

Ascospores form inside a sac-like meiocyte called an ascus, and the sexual fruiting body is called an ascoma.

• Hyphae differentiate to form pores, allowing the fungi to spread spores at the interface with the environment.

• funghi spreads through pores

Yeast

unicellular organisms that grow via budding

• some can can form hyphae

• example) cryptococcus neoformans

  

What are shmoos and how do they contribute to yeast reproduction?

Shmoos are cells in yeast that form during sexual reproduction. These cells fuse to create a zygote.

Symbiotic relationship

organisms live with each other in positive or negative relationships.

• usually involves 2 symbionts

Symbiotic interactions

1. Commensalism → on e partner benefits, other is unaffected

2. Parasitism → one partner benefits, while harming a specific host

3. Mutualism → each partner gains benefits from the other

Parasitic fungal pathogens

1. candida

2. cryptococcus

3. aspergillus

Mutualism

Mutualism is a relationship where both partner species benefit from each other and may fail to grow independently. In this relationship, the species rely on each other for survival, and one cannot thrive without the other. Mutualism can involve microbial partners alone or with a plant or animal host.

How do genomes change in mutualistic relationships?

In mutualism, the microbial genome often shows degeneration, with a reduction of essential genes for metabolism and protective structures. This means the microbes evolve to depend on each other, and once in the relationship, they cannot survive or grow independently. Examples of such mutualisms include lichens, and mycorrhizae.

Lichens

Lichens are a mutualistic relationship between fungi and photosynthetic algae or cyanobacteria. Neither symbiont can survive independently. The photosynthetic partner provides carbohydrates to the fungi, while the fungi supply water and minerals to the photobiont and offer physical protection. Nutrient exchange occurs at the "photobiont layer." Lichens can grow on various surfaces, such as bark, leaves, and rocks.