fungi & yeast

Fungi

Eucaryotic, unicellular to multicellular, microscopicto macroscopic organisms, spore bearer withabsorptive nutrition and lacking chlorophyll

Distribution

• Terrestrial, fresh water and marine• Also in polar region

ImportanceBeneficial-• act as decomposer, degrade complex organic

compound• Carbon, nitrogen, phosphorous and others are

recycled• Making of bread, wine, beer• Preparation of cheeses, soy sauce and sufu• Production of organic acids- citric acid, gallic acid• Drugs- cortisone• Antibiotics- penicillin,

Beneficial

• Immunosuppressive drug- cyclosporin• Important research tool

Harmful effect-• Pathogenic for plants, animals• Over 5000 sp attack economically valuable crops,

garden plants and many wild plants• About 20 new human fungal pathogens are

documented each year

Structure

• Single cell ( yeast) to multi-cellular• Cell wall is having chitin• Thallus- vegetative structure• Thallus consists of long, branched, thread like

structure called hyphae• Collection of hyphae make mycelia• Collection of mycelia make thallus

Mycelium

Nutrition and metabolism• Most fungi are saprophytes• They grow in dark, moist habitat rich with organic

materials• Release hydrolytic enzymes to digest substrate• Chemoorganoheterotroph• Storage material-glycogen• Use glucose or maltose and nitrogenous

compounds to synthesize their own amino acidsand proteins

• They are usually aerobic except yeast(facultativeanaerobe)

• Obligatory anaerobes are found in rumen

Reproduction-asexual1. Transverse fission-

2. Budding-

Reproduction3.Arthrospore

4.sporangiospore

5.chlamydospore

6. Zoospore

7. conidiospore

Sexual reproduction

Zygospore

Ascospore

Ascocarp

Basidiospores

1

2

3

4

Classification

Sub class- UrediniomycetesMycelial or yeast form

5

Life cycle of Yeast

Ustiloginomycetes 6• Common corn pathogen, causes tumour in plants• Have specialized hyphae called appresorria for

penetrating host tissue• With the help of these tomours are formed and

fungi grow inside to produce spores calledteliospores

Glomeramycota 7• Ecologically important• Eg. Mycorrhizal fungi- association between fungi

and plants

Importance of Mycorrhiza

• Fungus help protect its host from stress• Delivers nutrients from soil• Fungus get carbohydrate from the plant

Microsporidia 8• Confusing taxonomy(curious fungi)• Considered as protist• Some are pathogens• Are obligatory parasite, infects insects, fish,

human (AIDS patients are the target)• Causes diarrhoea, pneumonia, encephalitis,

nephritis• Morphology of spore- unique

polaroplast

exospore

endospore

nucleus

Polar tube

Posterior vacuole