Fungi, Yeast, Penicillium, Economic importance of fungi, General structure of fungi, Reproduction in fungi, plasmogamy, Harmful effect of fungi

1. STRUCTURE OF FUNGI
R. NITHYA M. Sc., M. Phil., PGDCA., (Ph. D)
ASSISTANT PROFESSOR IN BIOTECHNOLOGY
SRI ADI CHUNCHANAGIRI WOMEN’S COLLEGE, CUMBUM.
THENI DISTRICT, TAMIL NADU

2. Fungi
• Fungus (pl., fungi) is a Latin word which means mushrooms.
• The study of fungus is known as mycology.
• The fungi are evolutionary intermediates bridging plants and
microorganisms.
• Fungi are non-vascular plants without chlorophyll.
• Their mode of nutrition is hetero-trophic.
• They live as saprophytes or parasites or symbionts.

3. They are found in soil, water, air and in our food
stuffs.

4. They reproduce by means of spores.
There are about 1,00,000 species of fungi.
Fungi are economically useful.
They are used in many ways.

5. • At the same time, many fungi are harmful

8. General Structure
They are eukaryotic protists.
It includes yeast, molds and mushrooms.
The body of fungus is not differentiated into root, stem and leaves.
The body of fungus is called thallus.
Hence it is included under the group Thallophyta.

9. The study of fungus is called Mycology and the scientists who are studying
fungi are called Mycologists*.
The fungi of microbiological importance are
Yeast,
Penicillium,
Agaricus,
Aspergillus,
Rhizopus,
Puccinia, etc.

10. • Fungi are either unicellular or
multicellular forms.
• The yeasts are unicellular.
• The moulds and mushrooms are
multicellular.
• The multicellular fungi are in the form
of filaments.
• Each filament of the mycelium is called
a hypha.

11. The filamentous body is called mycelium.

12. • The mycelium can be divided
into the vegetative mycelium
which grows into the medium
and
• The aerial mycelium which
projects from the surface.

13.  The hypha is tubular in nature.
 It consists of cytoplasm enclosed by plasma membrane and
cell wall.
 The cytoplasm contains nucleus.

14. • This cytoplasm having many nuclei without cross walls is called a coenocyte

15.  In septate hypha cross walls (septa) are present.
 The septate hyphae may be uninucleate or multinucleate.
 The septum contains pores and the cytoplasm of all the cells
are interconnected.

16.  The fungal cell is surrounded by a cell wall.
 The cell wall is made up of fungal cellulose,
which is a form of chitin.
 Below the cell wall there is a plasma
membrane.
 The plasma membrane encloses the
protoplasm

17. • The protoplasm contains cell organelles and cell
inclusions.
• The organelles includes Golgi apparatus, mitochondria,
endoplasmic reticulum, vacuoles, etc.
• The inclusions include glycogen, oil droplets, pigments,
etc.
• Fungi are sedentary(inactive) and they are immobile.

18. •However, motile cells appear in their life cycles.
• The motile cells have flagella.
• Each flagellum has a central axoneme and a cytoplas
mic sheath.
•The axoneme has 9+2 fibrils.

19. • The nutrition in fungus is heterotrophic.
• They live as saprophytes or parasites or symbionts
• Lichen is a symbiont.
• It is an association of fungus and alga.

20. • Reproduction occurs by asexual and sexual methods.
• The asexual occurs by fragmentation or budding or sporulation.
• In frag-mentation, a small piece of hypha develops into a whole fungus.

21. • Budding is common in yeast.

22. • Sporulation is the production of spores.
• The asexual spores may be conidia or
aleuriospores or arthrospore or
chlamydospore or blastospore or
sporangiospore.
• Sexual reproduction occurs by producing
haploid spores such as, zygospores or
ascospores or basidiospores.

23. • In higher fungi such as, mushroom, the spores are located on a
specialised structure called fruiting body.

24. Yeasts
Yeasts are unicellular fungi.
• Saccharomyces is the commonly found yeast.
• It is haploid.
• It is commonly called baker's yeast or brewer's yeast because it is
commonly used in making bread, cakes, beers, wines, etc.
• It lives saprophytically in or on sugary solution, ripe fruits, decaying
vegetables, etc.
• It also occurs in the soil

25. • It is microscopic and unicellular.
• The thallus has no mycelium.
• It is made up of a single cell.
• It is oval in shape.
• The cell is covered by an outer cell
wall and an inner plasma membrane.
• The plasma membrane encloses the
protoplast.
• The protoplast is made up of
cytoplasm and nucleus

26. • The cytoplasm contains mitochondria, Golgi
apparatus, ribosomes, endoplasmic
reticulum, etc.
• A large vacuole is found in the center of the
mature yeast.
• The vacuole contains water, lipid granules,
etc
• The nucleus is haploid.
• It reproduces asexually and sexually.
• Asexual reproduction occurs by budding and
fission,
• Sexual reproduction occurs by the union of
two mature cells.
• It is called conjugation

27. • Sexual reproduction occurs by conjugation.
• During conjugation, two haploid cells come together.
• A conjugation canal is formed between them.
• The two haploid nuclei of the two yeasts fuse together to form
a diploid zygote.
• It undergoes reduction division to form eight haploid nuclei.
• Each haploid nucleus develops into an ascospore.
• The ascospore germinates into a haploid yeast.

29. Yeasts are used in the following ways
They are used for alcohol production.
Alcohol is produced by alcoholic fermenta-tion.
The process of the oxidation of sugar into alcohol and carbon-di-oxide under
anaerobic conditions is called alcoholic fermentation.
It is possible because yeast secretes an called zymase.
It is used in the preparation of ethyl alcohol, glycerol, ethers, fatty acids,
acetic acid, succinic acid, etc.
Yeasts are used along with starch to prepare yeast cakes.
 Vitamin B, is prepared from yeast cultures.

30. Penicillium
Penicillium is a fungus.
It is commonly called green mold because the conidia are green in
colour.
It is haploid.
The body of Penicillium is called thallus.
It is filamentous.
The filamentous body is called mycelium.
 The filaments are called hyphae.
They are septate.
There are horizontal and vertical hyphae.
 The horizontal hyphae are vegetative hyphae.
The vertical branches bear conidia and hence are called conidiophores.

33.  It reproduces vegetatively by fragmentation
asexually by conidia and
sexually by plas-mogamy.
In fragmentation, the mycelium breaks into small pieces and each piece
grows into a Penicillium
 The conidia are spherical bodies developed at the tip of vertical hypha.
They are dispersed by wind and each conidium germinates into a
mycelium.

34. Asexual reproduction by conidia formation

35. • Sexual reproduction occurs by plasmogamy.
• In plasmogamy, the cytoplasm and nuclei of male sex organ and female
sex organ fuse together.
• The plasmogamy produces a hypha with double nuclear called dikaryon.
• The dikaryon cells divide to form ascogenous hypha.
• It produces ascus.
• The ascus undergoes reduction division to produce 8 ascospores.
• The ascospores are haploid.
• They germinate into Penicillium.

36. Plasmogamy.

38. Economic Importance of Penicillium
 Many species of Penicillium are capable of producing organic acids such
as citric acid, fumaric acid, Oxalic acid, gluconic acid and gallic acid.

39. Penicillium camemberti and Penicillium roqueforti are
used in cheese making.

40. Penicillium patulum is used in the production of gentisyle alcohol.

41. Some species of Penicillium produce certain antibiotics.
These antibiotics are used to treat infectious diseases caused by aerobic and
anaerobic bacteria in man and animals

42. Harmful effect of Penicillium
Some species destroy leather and fabrics.

43. Many species of Penicillium attack and destroy fruits

44. Penicillium digitatum, Penicillium glaucum and Penicillium expansum spoil
the prepared foods.

45. Penicillium divaricatum destroy furnitures and woods.

46. Some species of Penicillium cause Penicillosis in man and animals.