Chapter 6. Fungi

☞ Fungi (균류, not 곰팡이)

- eukaryotic microbes

- several times larger than the bacterial cell

- broad diversity in structure and mode of life

- two types of microbes

-> yeast(진균) : single cell, fermentation ability

-> mold(곰팡이) : filamentous, important decomposer of organic matter

- 100,000 species were identified, 200,000 species are waiting to be discovered

- classified as the kingdom of Fungi by Whittaker system

Bracket fungus growing on a tree Penicillium notatum

1. Structure and growth 1) structure

- most species are composed of strands of cells (except yeast)

-> hypha (균사, pl. hyphae) : a single fungal strand

-> mycelium (균사체, pl. mycelia) : collection of hyphae

- nucleated, spore-bearing, no chlorophyll

- cell wall composed of chitin (polymer of NAG)

- septum (격벽) : partitions between cells

-> pores in septum

-> coenocytic (다핵체형) : no septum

Chapter 6. Fungi

Germinating spore

2) Nutrition

- heterotrophic -> excrete hydrolytic enzymes

-> cellulase, ligninase

- store carbohydrates as glycogen (vs starch by plants)

- saprobes (부생성, most fungal species live on dead organic matter)

-> some are parasites (live on living things)

- many species are acidophilic (btwn pH 5.0 and 6.0)

-> easy contamination in acidic foods (cheese, yogurt)

Chapter 6. Fungi

Blue cheese Yogurt

3) Reproduction

- most known fungi reproduce by both sexual and asexual methods

- reproduction depends on production of spore

-> arthrospore (분절포자) : hypha undergoes fragmentation

-> chlamydospore (후막포자) : thick-walled spore

-> thru the process of mitosis : yield genetically identical daughter cells - spore

-> sporangium (포자낭), conidiophore (분생자병)

Chapter 6. Fungi

☞ sexual reproduction

- all the mycelium have haploid nuclei

- involves cell fusion and spore formation

- gametes (배우자, haploid)

fusion of cells

zygote (접합자, diploid)

meiosis(감수분열)

form spores

Chapter 6. Fungi

2. Divisions of Fungi- four divisions

1. Zygomycota (접합균류문) :

-> fungi form sexually produced zygospore

2. Ascomycota (자낭균류문) :

-> form sexually produced ascospore within saclike body

3. Basidiomycota (담자균류) :

-> form sexually produced basidiospore on supportive structure

4. Deuteromycota (불완전균류) :

-> currently no sexually produced spores are recognized

Chapter 6. Fungi

1) Zygomycota

- fungi are called zygomycetes (접합균류)

- produce zygospore (접합포자, diploid cell) from fusion of two sexually opposite cells

- ex) Rhizopus stolonifer : 빵에 피는 일반적 검은 곰팡이

Chapter 6. Fungi

2) Ascomycota

- fungi are called Ascomycetes (자낭균류, sac fungi)

- form tiny spore-containing sac (ascus, 자낭)

- form ascospore (haploid) :

=> haploid nuclei -> fuse -> diploid cell -> meiosis -> eight haploid ascospore

- ex) Penicillium, Aspergillus

Chapter 6. Fungi

자낭균류

3) Basidiomycota

- fungi are called Basidiomycetes (담자균류, club fungi)

- well known as mushroom (basidiocarp, 담자과 = spore producing body of fungus)

- have long dikaryotic stage (two haploid nuclei)

-> basidiocarp = dense mass of dikaryotic hyphae

Chapter 6. Fungi

담자균류 생활사

3. Other fungi1) Yeast (beneficial or harmful)

- Saccharomyces : nonpathogenic genus of yeast

-> S. cerevisiae : 제빵, S. ellipsoideus : 알콜발효

- Candida albicans : infectious yeast, dimorphic life (oval yeast or filamentous hypha)

- reproduction by budding (동종이형)

Chapter 6. Fungi

S. ellipsoideus (a) and S. cerevisiae (b)Dimorphic C. albicans

2) Lichens (지의류)

- organisms resulting from association btwn a fungus and photosynthetic partner

- cyanobacterium or unicellular green algae

- lichen mass = 90% fungal + 10% photosynthetic partner

- can grow in harsh environments (desert, arctic zone, rocky area)

- photosynthetic partner -> provide sugars and carbohydrtaes

- fungal partner -> provide nutrients and protection from harsh environments

Chapter 6. Fungi

3) Mycorrhizae (균근)

- symbiotic mutualistic association btwn fungi and vascular plants

- fungus -> supply more nutrient(phosphorous)

- plants -> provide photosynthetic products

crusty lichen cross section of a lichen

Chapter 6. Fungi

Mycorrhizae

기공주변 미생물1. 근권(Rhizosphere)2. 내권(Endosphere)3. 엽권(Phyllosphere)

식물 : 고정된 탄소의 6-21% 뿌리 통해 분비

미생물 : 뿌리구조 강화양분흡수 촉진병원균으로부터 보호활성산소제거(엽권)

식물과 미생물의 공생