Basic knowledge about Mycology

1. Mycology
Module-I

2. Definition & Introduction
• Medical mycology is a branch of Microbiology
which deals with the study of fungi
• Fungi are eukaryotic and multicellular
• Fungi is different from bacteria in many ways
like

3. – Fungi has rigid cell wall
– Cell wall contains chitin, mannan, & other
polysachharides
– Cytoplasmic membrane contains sterols
– Fungi have true nuclei with nuclear membrane &
paired chromosomes
– They divide sexually & asexually or by both
process
– They may be unicellular or multicellular

4. Importance of Fungal Infections
• Most of the fungi or soil saprophytes
• Human infections are mainly opurtunistic
• That is when body defenses are low
• Modern advances in treatment such as
antibiotics, steroids & Immunosupressive
agents have led to a decrease in immunity &
lowering of normal protective bacterial flora
• This reasons led to increase in fungal
infections

5. Structure of Fungus
• The simplest type of fungus is the unicellular
yeast
• Yeast originated hundreds of millions of years
ago
• 1500 species are currently identified
• Measure 3-4 microns in diameter
• Some yeasts grow up to 40u in diameter

6. • Yeast like fungi have Sexual & Asexual
Reproductive cycles
• Most common mode of vegetative growth in
yeast is asexual reproduction by budding
• A small bud or daughter cell is formed on the
parent cell
• The nucleus of the daughter cell splits into a
daughter nucleus & enters into daughter cell
• Bud continues to grow until it separates from
mother cell

8. Hypha
• Elongation of the cell produces a tubular
thread like structure called the hypha
• Hypha consists of one or more cells
surrounded by a tubular wall
• In most fungi hypha are divided into cells by
internal cross walls called septa

9. • Hypha is of two types

10. • Septa are usually perforated by pores large
enough for ribosome's, Mitochondria &
sometimes nuclei two flow between cells.

11. Moulds
• Fungi which form Mycelia are called Moulds
or filamentous fungi
or
• Fungus that grows in the form of multicellular
filaments

12. • There are thousands of mould species
• Moulds have diverse life style
– Saprotrophs
– Mesophiles
– Psycrophiles
– Thermophiles &
– Very few are Opurtunistic pathogens of humans
• These are require moisture for growth & some
live in aquatic environment

13. • Moulds reproduce by large number of spores which
may contain single nucleus or multinucleate
• Reproduce by sexual & Asexual
• Moulds grow on dead and organic matter
• Their presence is visible to unaided eye when they
form large colonies

14. Classification of Fungi
• Depending on structure of cell fungi can be
divided into four classes
– Yeasts
– Yeast like fungi
– Moulds
– Dimorphic fungi

15. Yeast
• Yeast are unicellular fungi
• Which occur as spherical or elliptical cells &
reproduce by simple budding
• On culture they form smooth creamy colonies
• Only pathogenic yeast is Cryptococcus
neoformans

17. Yeast like Fungi
• Grows as yeast and also as elongated cells
resembling Hyphae
• They later form a Pseudomycelium
• Candida Albicans is pathogenic Yeast like
fungus

19. Moulds
• True mycelia
• Reproduce by forming spores
• Dermatophytes are examples of Moulds
• Dermatophytes require Keratin for Growth
• Dermatophytes causes Superficial Infections

21. Dimorphic Fungi
• These can occur as filamentous or as yeasts
depending on conditions of growth
• In host tissues or in cultures at 370C they
occur as yeast while in soil and in cultures at
220C they appear as moulds
• Most fungi causing systemic infections are
Dimorphic fungi

23. Mycoses (Fungal Infections)
• Human Fungal Infections are of Three types
– Superficial
– Systemic (Deep Seated)
– Opportunistic Infections
• Continued in 2nd module

24. Room No: B-308
y.praveen@galgotiasuniversity.edu.in
Ph: 9599047576