Introduction and Classification of Fungi

Swapnali Satish Pharande 1
Presented By
Ms. Swapnali Satish Pharande
Assistant Professor
Department of Pharmaceutics
Email: swapnali88pharande@gmail.com
Progressive Education Society’s
Modern College of Pharmacy For Ladies,
Moshi, Pune

CONTENTS
 Introduction
 Comparison of selected features of fungi and bacteria
 Classification of fungi.

LEARNING OUTCOMES
 After completion of this topic students should be able to:
 Describe classification of of fungi.
 Discuss the comparison between selected features of fungi and bacteria, moulds
and yeasts.

INTRODUCTION
• Fungus is a member of a large group of non-motile eukaryotic organisms which
exist as saprophytes (those living on dead or decaying matters), parasites or
commensals.
• It includes microorganisms such as yeasts and molds (British English: moulds),
as well as the more familiar mushrooms.
• Fungi are eukaryotic organisms with true nucleus and membrane bounded
organelles and reproduce either by budding or by forming spores.
• All fungi are chemoheterotrophs, requiring organic compounds for energy and
carbon.

INTRODUCTION
• Fungi are aerobic or facultative anaerobic.
• The cell wall of fungi made up of chitin, polysaccharides, and their cytoplasmic
membrane contains sterol.
• They were first identified by “Augustino Bassi” in year 1853 from Muscardine
disease of silkworm.
• Study of fungi is called mycology and the one study fungi is called Mycologist.

Comparison of Selected Features of Fungi And Bacteria
Characteristics Fungi Bacteria
Cell type Eukaryotic Prokaryotic
Optimum pH 4-6 6.5-7.5
Optimum
temperature
25 to 30˚C (saprophytes)
32 to 37˚C (parasites)
32 to 37˚C (mesophilic)
Cell membrane Sterols present Sterols absent except
mycoplasma
Oxygen
requirement
Strictly aerobic (moulds),
Facultative anaerobic (some
yeasts)
Aerobic to anaerobic
Table.1:Comparison of selected features of fungi and bacteria.

Comparison of Selected Features of Fungi And Bacteria
Characteristics Fungi Bacteria
Light requirement None Some photosynthetic
groups occur.
Carbon source Organic Inorganic/organic
Concentration of
sugar in laboratory
media
4 to 5% 0.5 to 1%
Cell wall components Chitin, cellulose or
hemicellulose
Peptidoglycan
Susceptibility to
antibiotics
Sensitive to griseofulvin,
Resistant to penicillins,
chloramphenicol etc.
Resistant to griseofulvin,
sensitive to penicillins,
tetracyclines, etc.
Table.2:Comparison of selected features of fungi and bacteria.

CLASSIFICATION OF FUNGI
A. Depending on cell morphology, Fungi can be divided into four classes:
I. Moulds
II. Yeasts
III. Yeast like fungi
IV. Dimorphic fungi.
B. Based on their sexual spore formation fungi are divided into four classes:
I. Phycomycetes
II. Ascomycetes
III. Basidiomycetes
IV. Fungi Imperfecti (Deuteromycetes).

A. Depending on cell morphology, Fungi can be divided into four
classes.
I. Moulds
• Fungi which form mycelia are called moulds or filamentous
fungi.
• It contain multiple identical nuclei and grow in the form of
mycelium or hyphae of filaments.
• It gives fuzzy appearance on the surface of media and forms
black, green, brown, orange or pink colours.
• They are strictly aerobic.
• They generally grow under 22-28˚C.
• They can reproduce either by sexual or asexual reproduction.
• Examples:
 Aspergillus Niger, Aspergillus fumigatus.
Fig.1: Mold
Fig.2: Mold
Swapnali Satish Pharande
9

A. Depending on cell morphology, Fungi can be divided into four classes.
I. Moulds
• The molds form large multicellular aggregates of long branching filaments,
called hyphae.
• There are vegetative hyphae and reproductive hyphae.
• Spores are borne on the reproductive hyphae. (Fungal spores should not be
confused with bacterial spores that are resistant bodies formed for bacterial
survival rather than reproductive purposes.)
• Spore size, shape and structure are used in the classification and identification
of fungi.
• 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.

I. Moulds
Fig.3:Types of hyphae seen in moulds.

A. Depending on cell morphology, Fungi can be divided into
four classes.
II. Yeasts
• Yeast are large (5 to 8µ), round, oval or elongated unicellular
fungi.
• Most of them reproduce by an asexual process called
budding in which the cell develops a protuberance which
enlarges and eventually separated from the parent cell.
• On culture, they forms circular, smooth, cream white
colonies.
• They are aerobic and some are facultative anaerobic.
• They generally survive in 32-37˚C.
• Examples:
 Saccharomyces cerevisae,
 Cryptococcus neoformans.
Fig.4:Yeasts

III. Yeast like fungi
• In some yeasts like Candida albicans, the bud remains attached to the mother
cell and elongates, followed by repeated budding and forms chains of elongated
cells of fungi known as pseudohyphae.
• These can be differentiated from true hyphae because they have a
constriction at the septa are also present at the branching point.
• On solid media moist creamy coloured colonies are produced.
Fig.5:Pseudohyphae

IV. Dimorphic fungi
• Some fungi mainly pathogenic species exhibit dimorphic i.e. two forms of
growth.
• Such fungi can grow either as a mold or as a yeast.
• The mold like forms produce vegetative and aerial mycelium.
• The yeast like forms reproduce by budding.
• Frequently dimorphism is temperature as well as CO2 dependent.
• At 37˚C, fungus grows yeast like growth.
• At 25˚C it shows moulds like growth.
• Examples: Mucor rouxii, Histoplasma capsulatum, Blastomyces dermitidis and
Sporothrix schenckii.

IV. Dimorphic fungi
Fig.6:Dimorphic Fungi Fig.7:Dimorphic Fungi

B. Based on their sexual spore formation fungi are divided into four classes
I. Phycomycetes
• They are fungi having non-septate hyphae (lower fungi).
• They form endogenous asexual spores (sporangiospore) contained within sac
like structures called sporangia.
• Phycomycetes also produce sexual spores known as oospores and zygospores.
• Examples: Mucor, Rhizopus, etc.
• The algal fungi: bread molds and leaf molds.
• The only known mycosis (fungal disease) caused by fungi of this class is
mucormycosis, a very rare fungal growth of the upper respiratory tract, bronchial
mucosa, and lungs.
• It occurs largely as a complication of a chronic, debilitating disease, such as
uncontrolled diabetes.

I. Phycomycetes
Fig.8: Phycomycetes

II. Ascomycetes
• They form sexual spores within a sac and are called ascospores.
• The sac is called ascus.
• They form septate hyphae.
• Ascomycetes include both yeasts and filamentous fungi.
• Examples: Histoplasma, Candida, etc.
• The sac fungi: yeasts, mildews, and cheese molds.
• Fungi of this class are implicated in only three fungus diseases, all of which are
rare.

II. Ascomycetes
Fig.9:Ascomycetes Fig.10:Ascomycetes

III. Basidiomycetes
• They reproduce sexually and form septate hyphae.
• These basidiospores are borne at the tip of the basidium.
• Example: Cryptococcus neoformans.
• Mushrooms, toadstools, rusts, and smuts.
• The only pathogens in this class are the mushrooms of the genus Amanita,
which cause severe systemic poisoning (sometimes death) when eaten.

III. Basidiomycetes
Fig.12:Types of Basidiomycetes
Fig.11:Basidiomycetes

IV. Fungi imperfecti (Deuteromycetes)
• They are also called Deuteromycetes or Hyphomycetes.
• They consist of groups of fungi whose sexual phases have not been identified.
• Many imperfect fungi form septate hyphae and asexual conidia.
• A majority of the pathogenic moulds, yeasts, yeast-like fungi, and dimorphic
fungi belong to the group fungi “imperfecti” .
• Examples: Trichophyton, Epidermophyton.
• Fungi imperfecti : a heterogeneous collection of fungi without sexual
reproduction.
• Most of the pathogens encountered in medical mycology belong to this class.

IV. Fungi imperfecti (Deuteromycetes)
Fig.13: Fungi imperfecti Fig.14: Fungi imperfecti( Deuteromycetes)

REFERENCES
1. Pharmaceutical Microbiology By Chandrakant Kokare, Nirali Prakashan, ISBN:
978-93-87686-60-12nd edition (2019):8.1-8.5.
2. file:///C:/Users/Administrator/Downloads/MORPHOLOGYANDGENERAL.pdf

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