the fungi

Fungus

Kingdom

Mycology

Discipline

Fungus

Kingdom

Mycology

Discipline

Eukaryotic organisms

Cell Type

Aerobic or facultatively anaerobic metabolism

Metabolism

Heterotrophic nutrition

Nutritional Mode

Saprophytic or parasitic lifestyle

Possible Nutritional Strategies

Most fungi act as decomposers

Role of fungi in Ecosystem

Unicellular or multicellular structure

Cell Structure

chitin in molds and glucans in yeasts

Cell Wall Composition

Reproduce by sexual and asexual methods

Reproduction

~50 000 species identified to date

number of Identified Fungi Species

Mushrooms, puffballs, gill fungi

Macroscopic Fungi

Molds and yeasts

Microscopic Fungi

unicellular, colonial, or complex/multicellular

Possible Fungal Forms

Decompose organic matter, aid plant roots, make antibiotics, alcohol, organic acids, vitamins

Key Benefits of Fungi

Eaten directly or used to flavor foods

Fungal Uses

Cause human disease, food spoilage, timber and crop destruction

Major Disadvantages of Fungi

Dutch elm disease, rusts of wheat, corn, barley

Notable Plant Diseases

multicellular with thick polysaccharide walls

what are molds?

appear cottony, hairy, or velvety

Mold Colony Texture

woven mass of hyphae forming the mold body

Mycelium Definition

septated, coenocytic, aerial, vegetative, or reproductive

Hyphae Types

form the visible mass of growth

Vegetative Hyphae Role

produce spores

Aerial Hyphae Role

Septate hyphae have cross-walls called septa

Septate Hyphae

Non-septate hyphae are one continuous cell

Coenocytic Hyphae

round or oval unicellular fungi

Yeast Shape

thin layers of mixed glycans

Yeast Cell Wall

Yeasts reproduce by budding

Yeast Reproduction Mode

Bud scar remains on mother; birth scar on daughter

Bud and Birth Scars

Yeasts

what forms Pseudohyphae?

soft and uniform like bacteria

Yeast Colony Appearance

uses methods similar to bacteria

Yeast Identification

Saccharomyces cerevisiae, Candida albicans, Cryptococcus neoformans

Common Yeast Species

Budding process: nucleus divides, migrates, bud separates

Budding Process Steps

Fission yeasts divide symmetrically; budding yeasts asymmetrically

Yeast Growth Types

grow as mold at room temperature and yeast at body temperature

Dimorphic Fungi Definition

Sporothrix schenckii and Histoplasma capsulatum

Examples of Dimorphic Fungi

Pathogenic dimorphs are yeast-like at 37 °C and mold-like at 25 °C

Pathogenic Dimorphism Temperatures

Fungi absorb nutrients from organic substrates (heterotrophic)

Fungal Nutrition

feed on dead plants and animals

What does saprobic feed on?

grow on living organisms but rarely require a host

Parasitic Fungi

Fungi tolerate nutritionally poor, high-salt or high-sugar environments

Environmental Adaptation

Cultivation requires aerobic (or facultative) conditions and pH 5.6-6.3

Basic Cultivation Conditions

include acidic fruits and vegetables

Natural Growth Media

Sabouraud’s Dextrose Agar and Rice/Oatmeal Agar are artificial media

Artificial Growth Media

by hyphal extension and spore formation

how do fungi reproduce?

allow reproduction and dispersal through air, water, living things

Spore Function

on a favorable substrate and form new colonies

where do spores germinate?

Sporangiospores form inside a sac-like sporangium on a sporangiophore

Asexual Spore – Sporangiospore

Conidiospores (conidia) are free spores not enclosed in a sac

Asexual Spore

combines genes of two parents for variation

Sexual Spore Formation Purpose

spore formed inside an ascus

Sexual Spore – Ascospore

formed externally on a basidium

Sexual Spore – Basidiospore

Main classification criteria: sexual spores, mycelial form, pigmentation, cell structure

Fungal Classification Bases

Ascomycetes produce ascospores in asci and have septate hyphae

Ascomycetes Characteristics

baking bread, wine making, gourmet morels/truffles

Ascomycetes Benefits

Chestnut blight, Dutch elm disease, ergot

Ascomycetes Disadvantages

form basidiospores on basidia and have septate hyphae

Basidiomycetes Characteristics

edible mushrooms

Basidiomycetes Benefits

plant parasites like black stem rusts

Basidiomycetes Disadvantages

lack sexual spores

Deuteromycetes Definition

cheese production, penicillin source

Deuteromycetes Benefits

serious human diseases

Deuteromycetes Disadvantages

Oomycetes have flagellated spores and produce oospores

Other Class – Oomycetes

can cause downy mildew of grapes and potato blight

Oomycetes Diseases

form zygospores and are often coenocytic

Other Class – Zygomycetes

infect diabetics and immunocompromised patients

Zygomycetes Concerns

Nearly 300 fungal species can infect humans

Number of Pathogenic Fungi

Community-acquired, environmental, and hospital infections are main categories

Fungal Disease Types

affect AIDS patients

Opportunistic Infections

Fungal cell-wall substances may trigger allergies

Fungal Allergens

Poisonous mushrooms can be lethal (fungal toxins)

Fungal Toxins

Fungi may infect corn and grain, harming livestock that consume them

Agricultural Pathogens

Up to 40 % of fresh produce is spoiled by fungi during shipping

Food Spoilage Statistic

Polyene antibiotics include Amphotericin B and Nystatin

Common Polyene Antifungals

Fluconazole and Ketoconazole

Common Azole Antifungals

Flucytosine and Griseofulvin

Miscellaneous Antifungals