CSU1346–Mycology and Phycology

Lecture 3: Morphology & Importance of fungi

 Topics to be covered today

 Morphology of fungi
 Importance of fungi
 MORPHOLOGY
• The body of the fungi is known as thallus

• Fungi vary widely in size and shape, from unicellular microscopic organisms to
multicellular forms easily seen with the naked eye

• Individual cells range from 1 µ to 30 µ. Microscopic fungi exist as either molds or

yeasts or both. Fungus spores range in size from about 4 micrometers to more than
100 micrometers

• The chitin in cell wall adds rigidity and structural support to the thin cells of the
fungus, and makes fresh mushrooms crisp.
• The hyphae Without crosswalls as in the case of lower fungi (chytrids and

zygomycetes) or, Divided into compartment by formation of septa in the higher

fungi (ascomycetes and basidiomycetes).

• Most members of the kingdom Fungi lack flagella; the structures are

completely absent in all stages of their life cycle. The only exception are

the chytrids, which produce flagellated gametes.

 CONTINUED….

• When reproductive hyphae are produced, they form a large organized structure called
a sporocarp, or mushroom

• Cytoplasmic membrane consist of ergosterols

• Possess true nuclei with nuclear membrane & paired chromosome

• A few types of fungi have structures comparable to bacterial plasmids (loops of DNA).
Fungal cells also contain mitochondria and a complex system of internal membranes,
including the endoplasmic reticulum and Golgi apparatus.

• Divide sexually, asexually or by both

• Most fungi are obligate or facultative aerobes

YEASTS

 Yeasts are unicellular (mostly ascomycete, basidiomycete, or members of the deuteromycete

group) fungi

 size of yeast is ranged from 1 to 5 µm in width and from 5 to 30 µm or more in length

 Saccharomyces cerevisiae, commonly referred to as brewer’s or baker’s yeast, is generally

ellipsoid in shape & consists of glucan (a polysaccharide compound) and mannoproteins.

 There is great diversity in cell shapes and modes of cellular reproduction in the yeasts

 Yeast is eukaryotic, which means they contain organelles that are usually found in the cells of

higher animals.

 Yeasts are single-celled forms that reproduce by budding, whereas molds form multicellular hyphae
 Agar‐grown yeasts shows great diversity in terms of color, texture, and geometry

(peripheries, contours) of giant colonies.

 Several yeasts are pigmented and the following colors may be visualized in surface‐

grown colonies: cream (e.g. S. cerevisiae); white (e.g. Geotrichum candidum); black

(e.g. Aureobasidium pullulans); pink (e.g. Phaffia rhodozyma); red (e.g. Rhodotorula

rubra); orange (e.g. Rhodosporidium spp.), and yellow (e.g. Cryptococcus laurentii).

 The pigments of some yeasts have biotechnological uses, including astaxanthin

from Phaffia rhodozyma in aquacultural feed supplements for farmed salmon (that

are unable to synthesize these natural pink compounds).

MOLDS

 These are the types of fungi that grown well in warmth and moist environment. They can be found on the

surface of different food, from where it can get nutrients.

 The molds form large multicellular aggregates of long branching filaments, called hyphae. All molds are

fungi but all fungi are not mold.

 Mold spores can range from 1 micron to 40 microns in size. In comparison, the size of a single strand of

human hair is approximately 70 microns in diameter. That means that if a mold spore was 10 microns in

size, it would take 7 of them stacked together to equal one single strand of hair.

 New hyphae generally rise from a spore which on germination puts out a germ tube or tubes. These germ

tubes elongate and the branch to form hyphae. The hyphae are about 5 to 10 µm wide.
•The hyphae are made up of an outer tubelike wall which is enclosing a

cavity, the lumen, which is loaded with protoplasm.

•A double-layered membrane is present between the protoplasm and the

wall known as plasmalemma, which surrounds the protoplasm.

•The hyphal wall is made up of microfibrils which is consist of hemicelluloses

or chitin: true cellulose found only in the walls of lower fungi.

 There are vegetative hyphae and reproductive hyphae. Spores are borne

on the reproductive hyphae.

 The vegetative part help in the absorption of nutrients while the reproductive

parts involved in the formation of reproductive structures, such as thalli are known

as eucarpic

 In some fungi, the thallus does not exhibit this differentiation and after a phase of

vegetative growth, changes into one or more reproductive structures. Such thalli

are known as holocarpic. The greek

word holos mean entirely and karpos means fruit.

 The tube-like hyphae are responsible for the fluffy appearance of the macroscopic

mold colony. The hyphae and other structures combine to form an elaborate

network called a mycelium.

Mucor mucedo Aspergillus nidulans
Importance of Fungi

1.The Mycorrhizal relationship of fungi benefits various plants in

many ways. For instance, fungi get nutrients from plants and it

provides phosphates which is readily available for the plant.

2.Some fungi function as biological insecticides, for

example, Beauveria bassiana helps the farmers to control such

pests as the emerald ash borer that can cause damage to plants.
 The emerald ash borer is an insect that attacks ash trees. It is in turn parasitized by a
pathogenic fungus that holds promise as a biological insecticide. The parasitic fungus appears
as white fuzz on the body of the insect.

Fungus are successively used in biological control of pests. For example – Empausa sepulchralis, Cordyceps
melonhae. Use of fungal pesticides can reduce environmental hazards by a great extent.
3. Fungi are heterotrophic organisms hence they get their nutrients from dead

organic matter & they increase the fertility of the soil.

4. In industrial fermentation, the saprophytic fungi are used for brewing beer,

production of wine and antibiotics (penicillin).

5. Food – Mushrooms species are edible which are cultured and are used as

food by humans. Morels, shiitake mushrooms, chanterelles, and truffles are

considered delicacies.The humble meadow mushroom, Agaricus campestris,

appears in many dishes.

morel mushroom is an ascomycete much appreciated for its delicate taste.

6. Molds of the genus Penicillium ripen many cheeses. They originate in the
natural environment such as the caves of Roquefort, France, where wheels of
sheep milk cheese are stacked in order to capture the molds responsible for the
blue veins and pungent taste of the cheese.
7. Wild yeasts are acquired from the environment and used to ferment sugars
into CO2 and ethyl alcohol under anaerobic conditions. fermentation of sugar
by an enzyme called zymase producing alcohol which is used to make wine
8. Valuable drugs isolated from fungi (Tolypocladium inflatum) include the

immunosuppressant drug cyclosporine (which reduces the risk of rejection after organ

transplant), the precursors of steroid hormones, and ergot alkaloids used to stop bleeding.

9. Aspergillus terreus, another important medicinal fungus, creates lovastatin which is

beneficial for lowering cholesterol, Aspergillus niger is used for the synthesis of different

steroids

10. Psilocybin is a compound found in fungi such as Psilocybe semilanceata and Gymnopilus

junonius, which have been used for their hallucinogenic properties by various cultures for

thousands of years.
11. Some species of fungi are used in the detection of certain elements such as
Copper and Arsenic in soil and in the production of enzymes. For instance,
biological and genetic research on fungi named Neurospora led to the One
Gene One Enzyme hypothesis.
12. The fungi live in a symbiotic relationship with the plant roots known as
mycorrhiza. These are essential to enhance the productivity of farmland. 80-
90% of trees could not survive without the fungal partner in the root system.
Disadvantages of Fungi

1.Molds can cause food damage. They also release spores which are

responsible for different health problems i.e. breathing difficulties.

2.Molds also release toxins such as aflatoxin or myotoxins among

others that can cause serious health problems to a human being.

3.There are different poisonous mushrooms that can cause death when

consumed.
Thank
you
Dr. Jyoti Mehta
Assistant Professor
School of Biotechnology.
Shoolini University
Village Bajhol, Solan (H.P)
jyotimehta@shooliniuniversity.com