Lecture: What are Fungi? BIOL 319- Spring 2017

Biology of Fungi

What are Fungi? BIOL 319

Fungi in the Tree of Life (cont.)

  Coincides with the rapid

expansion of multi-

cellular organisms   Major multicellular

eukaryotes are divided

into Kingdoms   Animals

Artistic vision of mushrooms among plants.

  Plants Source: interactive.usc.edu/members/jchen/   Fungi

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Fungi in the Tree of Life (cont.)

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Fungi in the Tree of Life

  Living organisms on

earth first arose about

3.5 billion years ago   Prokaryotic   Anaerobic

  Oldest fossils of fungi are about 460 million years old

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Fungi in the Tree of Life (cont.)

  Each of these three kingdoms differ in

their basic cellular structure and mode of

nutrition (defined by Whittaker, 1969)   Plants - photosynthetic, cellulosic cell walls  

Animals - digestive systems, wall-less cells  

Fungi - absorptive nutrition, chitinous walls

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Fungi in the Tree of Life (cont.)

  The estimates for the expansion of

multicellular organisms are based upon

phylogenetic analyses of Carl Woese   Examined ribosomal RNA (rRNA)

  Present in prokaryotes and eukaryotes   Relatively stable, but changes occur over time;

thereby acting as a chronometer   Distinguished three separate groups

(Domains) of living organisms BIOL 319

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ascospores (arrow) within the ascocarp. Source: www.ucmp.berkeley.edu/fungi/fungifr.html

Fossilized perithecium of what is believed to be a fungus of the genus Savoryella. Note the

Lecture: What are Fungi? BIOL 319- Spring 2017

Fungi in the Tree of Life (cont.)

  Domains - rRNA sequence differences

correlate with differences in cellular

structure and physiology   Bacteria - “true bacteria”

  Archaea - “ancient prokaryotes”

  Eucarya - eukaryotes   Taxonomic grouping of “Kingdom” lies

beneath that of “Domain” BIOL 319

Fungi in the Tree of Life (cont.)

  Though the fossil evidence suggests

fungi were present on earth about 450 million years ago, aquatic fungi (Phylum

Chytridiomycota) most likely were present about a million years before this

time   About 354 - 417 million years ago, fungi

evolved with primitive land plants

BIOL 319 Defining the Fungal Kingdom

  Mycology is the study of fungi

  Myco- = fungi   -ology = the study of

  Mycology originally arose as a branch of

botany because fungi were once believed

to be “achlorophyllic” plants

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Figure 1.1, Deacon (2006) Fungal Biology, 4th ed.

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Fungi in the Tree of Life (cont.)

  These plant-associated fungi probably

helped their photosynthetic partners

gather nutrients from the harsh soils of

the time   These fungi were the early ancestors of

the present day phylum Glomeromycota   Despite plant-fungus co-evolution, fungi

are more closely related to animals BIOL 319

Why Study the Fungi?

  There are over 100,000 species of

known fungi and probably 15 times that

many that have yet to be discovered   Fungi are an extremely important part of

the ecosystem   Recycling of minerals and carbon

  Cause plant and animal diseases   Source of food, medicines, and chemicals  

Important models in scientific research BIOL 319

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Lecture: What are Fungi? BIOL 319 - Spring 2017

A Brief History of Fungi

  Greeks (about 300 B.C.)

believed truffles were

produced by thunder   Oldest illustration of

fungi was found among the ruins of Pompeii

A truffle. Source: www.truffle-and-truffe.com (A.D. 79) that depicted

edible mushrooms BIOL 319

A Brief History of Fungi

  Euripides (A.D. 450-456) recorded the

first mushroom poisoning deaths

Amanita muscaria, one of the most

poisonous mushrooms in the world.

Euripides. Source: uk.wikipedia.org Source: www.myco-vaud.ch

BIOL 319 Copyright © 2009 Chester R. Cooper, Jr A Brief History of Fungi (cont.)

A Brief History of Fungi (cont.)

  During a period of the Middle Ages

(A.D. 1470 to 1670), books on ‘herbals’

were published that included illustrations

and descriptions of fungi   Remarkably similar to those of Greeks

  Used same methods to divide mushrooms

and truffles into poisonous and non-poisonous varieties

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Jerome Bock. Source: www.nndb.com

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  The German herbalist Jerome

Bock wrote in A.D. 1552: “Fungi and truffles are neither herbs, nor roots, nor flowers, nor seeds, but merely the superfluous moisture of earth, of trees, or rotten wood, and of other rotting things. This is plain from the fact that all fungi and truffles, especially those that are used for eating, grow commonly in thundery and wet weather.” [From Ainsworth (1976) Introduction to the History of Mycology, as cited in

Moore-Landecker (1996) Fundamentals of the Fungi, 4th ed.]

A Brief History of Fungi (cont.)

  Other cultures also believed the fungi

originated from thunder and lightning   Hindu god Soma was a child of thunderstorms who offered hallucinogenic fluids from Amanita muscaria, one of the world’s most poisonous mushrooms

  Similar legends existed in Guatemala and

Mexico BIOL 319

A Brief History of Fungi (cont.)

  Modern times in the

study of fungi began with the invention of the microscope (about 1590-1600) by Hans and Zacharias Janssen of Holland

Zacharias Janssen. Source: www.astrophotoclub.com/history/telescope.htm

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Lecture: What are Fungi? BIOL 319 - Spring 2017

A Brief History of Fungi (cont.)

A Brief History of Fungi (cont.)

  Robert Hooke used

the microscope to make the first drawings of a microscopic fungus (Mucor or Rhizopus) in 1665 and published them in his book Micrographia

Hooke’s drawing in Micrographia.

Source: www.unb.br/ib/cel/microbiologia

  In 1699, fungi are found

to be a component of

lichens   Anton van Leeuwenhoek

observes yeasts using a

microscope (1673)

British Soldier Lichen. Source: www.buenavistatownship.org

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BIOL 319 A Brief History of Fungi (cont.)

  Hereafter, the study of fungi exploded with many different contributions over the next 300 years, including the one gene-one enzyme hypothesis (Beadle

and Tatum, 1941) and the Source: www.laskerfoundation.org 2001 Nobel Prize for cell

division studies in yeast BIOL 319

Defining the Fungal Kingdom

  Fungi are simple,

eukaryotic microbes   Many are microscopic   Studies typically Macroscopic (above; from

Kendrick) and microscopic (below;

employ standard from Cooper) fungi

microbiological

techniques

BIOL 319 Copyright © 2009 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.)

Defining the Fungal Kingdom (cont.)

  Mycologists (fungal

biologists) have

traditionally studied

not only the true

fungi (e.g., mildew),

but also fungus-like

organisms (e.g.,

slime molds)

Physarum polycephalum, a slime mold, growing out of

Petri dishes (upper image) and a closer view of the

plasmodium phase (lower image) Source:

waynesword.palomar.edu/slime1.htm

  The kingdom Mycota

is comprised of the

true fungi   True fungi have the

following features:   Eukaryotic

Transmission electron micrograph of a fungal cell

showing typical eukaryotic structures. Source:

www.stchas.edu/faculty/zfitzgerald/fungi.jpg

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Lecture: What are Fungi? BIOL 319 – Spring 2017

Defining the Fungal Kingdom (cont.)

  Fungal features (cont.):

  Typically grow as

filaments, termed hyphae

(sing., hypha) via apical

growth [the latter differs

from the growth of other

filamentous organisms]

Scanning electron micrograph of a fungal hyphae growing on the surface of a leaf. Source: www.abdn.ac.uk/ims/h-em/images/sem4/pages/fungal-hyphae-on-leaf.html

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Defining the Fungal Kingdom (cont.)

Apical growth of a fungal hypha of Sclerotinia sclerotiorum.

Source: Fungal Cell Biology Group (www.fungalcell.org) BIOL 319

Defining the Fungal Kingdom (cont.)

Hyphal strand of a Streptomyces species. Note the newly dividing cell (arrow). Source: zoology.okstate.edu/zoo_lrc/biol1114/sample_tests/preview_material/exam1/s03/preview-exam1_s03.htm

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Defining the Fungal Kingdom (cont.)

  Fungal features (cont.):   Fungal hyphae

repeatedly branch to

form a network of

filaments termed a

mycelium (sing.,

mycelia) Drawing of a mycelium. Source: www8.nos.noaa.gov/

coris_glossary/index.aspx?letter=m BIOL 319

Defining the Fungal Kingdom (cont.)   Fungal features (cont.):

  Some fungi grow as a single-celled entity,

termed a yeast, that grows either by a

budding process or via binary fission

Budding yeast (left) and fission yeast (left). Sources: www.biochem.wisc.edu/yeastclub and

www.steve.gb.com/science/model_organisms.html BIOL 319

Defining the Fungal Kingdom (cont.)

  Fungal features (cont.):   Some fungi can switch growth

forms between a hyphal phase and a yeast phase, a property known as dimorphism

  Typically induced by environmental

conditions   A number of such fungi are disease-

causing agents of humans and

animals

Dimorphism of Candida albicans. Source: www.explorepub.com/articles/darkfield_charts/fungus9.html

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Lecture: What are Fungi? BIOL 319 - Spring 2017

Defining the Fungal Kingdom (cont.)   Fungal features (cont.):

  Heterotrophic (chemo-organotrophs) -

require preformed organic compounds   Absorb nutrients after degradation by

exogenously released enzymes BIOL 319

Defining the Fungal Kingdom (cont.)   Fungal features (cont.):

  Unique cell wall components   Chitin  

Glucans   Rare instances of cellulose, but definitely fungal cell walls are not as rich in this polymer as are plants

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Defining the Fungal Kingdom (cont.)   Fungal features (cont.):

  Typically have haploid nuclei   Hyphae often have a number of haploid nuclei present in each cell

  Some yeasts have a single diploid nucleus   Reproduce both sexually and asexually,

typically through the production of spores BIOL 319 Defining the Fungal Kingdom (cont.)   Fungal features (cont.):

  Other differences [ Deacon, Table 1.1] between fungi and animals and plants include:

  Histone types   Sensitivity of microtubules to inhibitors  

Manner of lysine biosynthesis   Membrane sterols

  Organellar structure/morphology

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Defining the Fungal Kingdom (cont.)

Asexual mitotically-derived spores (conidia; orange arrow in

above figure) of the fungus Scedosporium apiospermum and

the meiotically-derived spores (ascospores within a specialized

structure termed a cleistothecium; white arrow in figure to the

right) of the sexual form of the same organism given the

designation Pseudallescheria boydii

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Major Activities of Fungi   Plant parasites

  Irish potato blight of

the 1840s   Dutch elm disease

  Disappearance of

frogs in Costa Rica

Phytophthora infestans growing into the leaf of a potato plant (above) and the

resulting rotting tuber from infection by this fungus (right). Sources: www.seedquest.com/News/releases/2005/may/12297.htm and

www.science.siu.edu/plant-biology/PLB117/JPEG%20files/potato.blight.jpg

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Lecture: What are Fungi? BIOL 319 - Spring 2017

Major Activities of Fungi   Plant symbionts

  Lichens (can also

form with

cyanobacteria)   Mycorrhiza

Mycorhizzal fungus associated with roots of a pine. Source: www.virtualmuseum.ca/Exhibitions/Mushroom/English/Species/mycorrhizal.html

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Major Activities of Fungi (cont.)   Biological control agents

  Mycoparasites (other fungi)  

Entomopathogens (insects)  

Nematophagous (nematodes)

Nematode trapping fungus. Source: Kendrick BIOL 319

Major Activities of Fungi (cont.)   Toxin production (mycotoxins)

  Aflatoxins (peanuts and grains)

  Mushroom poisoning

Moldy corn due to the aflatoxin producer Aspergillus flavus. Source: www.ipm.iastate.edu/ipm/icm/2001/10-22-2001/earrot.html

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Major Activities of Fungi (cont.)

  Human pathogens

  About 200 known species of fungi are

known to infect humans   Diverse diseases including:

  Dandruff   “ring worm”

  Pneumocystis infection of HIV-infected persons

  Candidiasis (Candida yeast) BIOL 319

Major Activities of Fungi (cont.)   Decomposition

  Cellulose (plant material)

  Rumen fungi in cows   Dry rot

Dry rot due to the fungus Serpula lacrymans.

Source: www.grzyby.pl/gatunki/Serpula_lacrymans.htm

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Fungi in Biotechnology   Foods and flavorings

  Edible mushrooms   5 million tons produced worth $14 billion (1994)

  Diverse types now widely available in

supermarkets   Alcoholic beverages

  Breads, cheeses, soy sauce

  Quorn mycoprotein BIOL 319

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Lecture: What are Fungi? BIOL 319 – Spring 2017

Fungi in Biotechnology (cont.)

  Fungal metabolites

  Two categories   Primary - intermediates or end products of

common metabolic pathways essential for

normal cellular function   Secondary - diverse range of compounds

formed by specific pathways of a given

organism and not essential for growth (but may

provide some selection advantage) BIOL 319

Fungi in Biotechnology (cont.)   Fungal metabolites (cont.)

  Examples of secondary metabolites   β-lactam antibiotics, e.g., penicillins and

cephalosporins   Non-β-lactam antibiotics, e.g., griseofulvin,

gliotoxin, ciclosporins   Pullulan - film-wrap for food in Japan

  Chitosan - sewage clarification, plant defense

initiator BIOL 319

Fungi in Biotechnology (cont.)

  Fungal metabolites (cont.)

  Examples of primary metabolites   Citric acid (estimated 200,000 tons produced in

the year 2000) [soft drinks]   Gluconic acid (estimated annual production of

100,000 tons) [food additive]   Itaconic acid (estimated annual production of

80,000 tons) [paint and adhesive manufacture]

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Fungi in Biotechnology (cont.)   Enzymes and enzymic conversions

  Extracellular enzymes   Commercially valuable roles

  Food industry  

Bioconversions   Heterologous gene products -

expression of foreign proteins by fungi

having medical/industrial applications BIOL 319

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