Penicillium notatum

1. Penicillium
Kingdom Fungi

2. Taxonomic position
Kingdom : Fungi
Division : Ascomycota
Class : Eurotiomycetes
Order : Eurotiales
Family :Trichocomaceae

3. Occurrence
They are
• Common to occur
• Cosmopolitan genus
• Commonly called as green mold
• Found in variety of habitat  citrus fruits, jellies
, foot stuffs , old leather , paper , soil etc.
• Conidia of Penicillium are present everywhere
in air and soil
• It was accidently discovered by Alexander
Fleming , who was working on bacteria and his
culture got contaminated by Penicillium
notatum

4. Plant body - Mycelium
 It is well developed
 Profusely branched
 Composed of colorless , slender , tubular,
branched and septate hyphae
 Overall hyphae spreads on surface but
some hyphae penetrate inside the
substratum to absorb nourishment
 The mycelium becomes colored due to
production of colored conidia

5. Cell structure
 Hyphae is septate
 Each cell is uninucleate
 The cell wall is microfibrillar , and in Penicillium notatum ,
it is of 3 layers
 The outer layer is made up of glucan
 The next layer is made up of proteins
 the 3rd layer is made up if chitin fibrils embedded in
granular matrix
 The innermost layer is made up of pectic and
hemicellulose
 The plasma membrane surrounds the cytoplasm that
contains organelles like mitochondria , ribosomes and
endoplasmic reticulum in embedded form
 The reserve food is in form of oil globules
 The adjacent cells are connected by a pore present in
septa of their walls

7. Reproduction
It reproduces by
 Vegetative reproduction
 Asexual reproduction
 Sexual reproduction

8. Vegetative reproduction
• It takes place by fragmentation
• During fragmentation the hyphae breaks into short fragments
• That grows by repeated division into new mycelium

9. Asexual reproduction
 It takes place by formation of conidia
 Conidia are produced on special hyphae called
conidiophore
 The conidia are erect , brown and broom like
in fashion
 Each branch bears short branch at its tip ,
called metulae
 at each metula , there are bottle shaped
sterigmata
 Conidia are produced in chains at these
sterigmata
 Whole group of metulae and sterigmata are
called -- pencillus

10. Structure of conidia
 Each conidia is tiny, uninucleate, spore like structure,
 May be globose and ovoid in shape
 The spore wall is pigmented and it is made up
of two layers
 The outer layer is thick, pigmented is called exine
 The inner layer smooth, and thin called as intine
 Inside the spore wall plasma membrane is present ,
which encloses the mitochondria , ribosomes in
embedded form
 The reserve food is in oil globules

11. Development of conidia
 Each sterigmata is uninucleate
 During reproduction the nucleus conidia
divided into two
 One daughter nucleus along with some
cytoplasm migrate into the slightly swollen
tip of sterigmata
 The portion is then cut off from the rest of
the sterigmata by formation of cross walls
 The protoplast then contract slightly and
secretes its on wall
 The process repeats several times and chain
of conidia are formed
 Each newly formed conidia is uninucleate
but later own its nucleus divided several
times , making conidia multinucleated

12. Germination of conidium
The conidia germinates by producing
hyphae directly on falling on suitable
substrate

14. Oidia formation
 Penicillium hyphae when grown in sugar
medium , it divides into small, uninucleate
segments which become rounded and
separate into thin walled spore like structure
called oidia or oidiospore
 These increase in number by budding , this
is called torula stage , this is important in
bringing the fermentation of sugar into
alcohol
 The oidia when transferred to solid medium ,
germinates to form new mycelium

15. Torula stage

17. Sexual reproduction
 It is the perfect state of Penicillium
 All the species are homothallic
 The sexual reproduction is oogamous
 Male sex organ is called antheridia
 Female sex organ is called ascogonia

18. Ascogonium
 It’s a long , erect,
multinucleate , tubular
structure , with curved upper
end
 It arises from a uninucleate ,
septate hypha as a finger –
like lateral outgrowth which
elongates in to an
ascogonium
 The nucleus of the
ascogonium divides many
times mitotically to produce
32 to 64 nuclei.

19. Antheridium
 While the ascogonium is
developing ,
 A slender uninucleate branch
originates from a cell of the
same hypha adjacent to the
developing ascogonium , or
from neighboring hypha .
 This is called antheridial branch
 It grows up and coils around the
ascogonium
 The tip of the antheridial branch
swells up and cut off from rest of
the branch to form a uninucleate
antheridium

20. Fertilization
 The tip of the antheridia
comes into contact with the
wall of the ascogonium and
the wall of contact between
the two dissolves to form a
pore
 The protoplast of the
gametangia come in contact
with each other through this
pore
 The antheridial and
ascogonial nuclei arrange
themselves in pairs .
 Each pair is called a dikaryon

21. Cleistothecium development
 As soon as the septation of
ascogonium and development
of ascogenous hyphae starts
 The sterile hyphae present at the
base of ascogonium grow
upwards and surround the
sexual apparatus
 These hyphae become
interwoven to form a hollow ,
ball like structure , the peridium
 wall of ascocarp
 The ascocarp continues to grow
even after the maturation of
ascospores
 The ascocarp is without an
opening , therefore it is called
Cleistothecium

23. Dispersal and germination of
ascospores
 The asci are evanescent -
- dissolve soon after
the formation of
ascospores, leaving the
ascospores free in the
ascocarp.
 The ascospores are
released by the decay of
the wall of the ascocarp
 Ascospores germinate by
the formation of a germ
tube to form a new
mycelium