Divisions of Fungi

• Basidiomycota– Includes mushrooms– Called basidiomycetes– Basidiocarp– Dikaryotic stage (2 nuclei)– Basidiospores– Basidium

Divisions of Fungi: Life Cycle of Basidiomycota

Figure 8.7: The life cycle of a typical basidiomycete

Divisions of Fungi

• Basidiomycota– About 25,000 named species

• Puffballs

• Shelf fungi

• Earthstars

• Stinkhorns

• Jelly fungi

• Gill fungi (including poisonous ones)

– Rust disease– Smut disease

Divisions of Fungi

• Deuteromycota– About 25,000 species– No currently identified form of sexual reproduction– Also known as deuteromycetes or Fungi Imperfecti– Conidia– Many human pathogens

• Dermatophytes of athlete’s foot

Beneficial and Harmful Fungi

• Yeasts– Saccharomyces

• Ascomycota• Single cells• Saccharomyces cerevisiae

– Baking– Accumulation of CO2 during

Krebs cycle makes dough rise– Enzymes break down gluten,

giving spongy texture• Saccharomyces ellipsoideus

– Brewing– Fermentation results in

production of CO2 and ethanol– Different starting materials give

rise to wines and beers

Fig. 8.1a

Reproduced by permission of the National Research Council of Canada; E.M. Peterson, R.J. Hawlay, and R.A. Calerone. The Canadian Journal of Microbiology, 22(10): 1518-1522.

Beneficial and Harmful Fungi

• Lichens– Association between fungus and photosynthetic partner– Approximately 15,000 lichen species– Almost all have an ascomycetes as the fungus– Most frequent photosynthetic partners

• Trebouxia (green algae)

• Trentephila (green algae)

• Nostoc (cyanobacterium)

Fig 8.10 lichens© Popovici loan/ShutterStock, Inc.

Beneficial and Harmful Fungi

• Lichens– Grow in a diversity of environments

• Arid deserts

• Arctic zones

• Bare soil

• Tree trunks

• Rocky areas

– Photosynthetic partner provides sugar and carbohydrates– Fungal partner supplies protection and basic biochemical building

blocks– Can survive in as little as 2% water– Very slow growth (less than 10 mm per year)

Beneficial and Harmful Fungi

• Mycorrhizae– Mutualistic fungi that live amongst roots of vascular plants– Over 5,000 species– Plant provides photosynthetic products– Fungi provide more nutrients than plant can absorb through roots

alone– Garden plants typically associate with zygomycetes

Beneficial and Harmful Fungi

• Fungi and human disease– Candida albicans

• Normal vaginal flora

– Held in check by other acid-producing flora

– Overuse of antibiotics, which may kill normal flora, leads to yeast infection (candidiasis)

– Can be treated» Antifungal creams» Eating yogurt

• Normal oral flora

– If immune depleted (e.g., AIDS), can infect mouth

– Disease is called thrush

– Treatment with oral antifungals

Figure 8.11: An SEM of Candida albicans

Reprinted with permission from the American Society for Microbiology (Balish, E., Balish, M.J., Salkowski, C.A., Lee, K.W., and Bartizal, K.F; Appli. Environ. Microbiol, 1984 May; 47(4): 647-625.)

Beneficial and Harmful Fungi• Fungi and human disease

– Cryptococcus neoformans• Infects lungs and meninges

– Tinea diseases• Skin infections

– Athlete’s foot

– Barber’s itch

– Jock itch

– Ringworm

Fig. 8.12: C. neoformansFigure 8.13: Ringworm

from Trichopyton tonsurans

Re

printed

with

perm

ission fro

m th

e A

merica

n So

ciety for M

icrob

iolo

gy (AS

M

Ne

ws. D

ece

mbe

r 199

8, Vo

l. 64(1

2): 693-

698

) Pho

to courtesy o

f Docto

r Stu

art Levitz,

Un

iversity of M

assach

usetts Med

ical

Ce

nter.

Re

printed

with

perm

ission fro

m th

e A

merica

n So

ciety for M

icrob

iolo

gy (D

ykstra, M

.A., F

riedm

an, L

. and

M

urphy, J.W

.; Infe

ct. Imm

un. 19

77 M

ay; 1

6(1): 1

29-13

5.)

© M

edic

al-o

n-Li

ne/A

lam

y Im

ages

Beneficial and Harmful Fungi

• Fungi and human disease– Aspergillus spp. (A. fumigatus, A. flavus, A. niger)

• In large quantities or in the immunocompromised spores may infect the lungs causing Aspergillosis

– Coccidioides immitis• Respiratory disease• American Southwest• May proceed to meningitis• Sometimes called Valley Fever

– Histoplasma capsulatum• Found in bird droppings• Respiratory illness

– Blastomyces dermititidis• Found in bird droppings• Respiratory illness