Eurotium, commonly known as Aspergillus, is a genus of fungi that reproduces both sexually and asexually. It is commonly found growing on damp organic materials. Asexually, it produces multicellular structures called conidiophores that bear chains of spherical spores called conidia. Sexually, specialized hyphae called archicarps develop and produce female sex organs called oogonia. If fertilized by male sex organs called antheridia, the oogonia undergo meiosis and form chains of cells called ascogenous hyphae, which then produce sacs called asci containing ascospores. The ascospores and conidia allow the fungus to spread and

1. Name: Aleeha Bushra
Class: MSC Botany
Eurotium(Aspergillus)

2. Eurotium
 Systematic position
 Kingdom Fungi
 Division Ascomycota
 Class Eurotiomycetes
 Order Eurotiales
 Family Trichocomaceae
 Genus Eurotium
 Species Eurotium amstelodami

3. Habitat
 They are commonly found as filamentous mouldy growth on the surface of
damp fruits and vegetables preserved fruits, moist breads, jams and various
conserves, and also on imperfectly dried herbarium specimens. Many species
are commercially important on account of their hydrolysing powers on starch
and sugars and cause fermentation to citric and oxalic and rarely to alcohol.
 Most of the species of Eurotium are saprophytes and occur on a wide variety of
organic substrata. A few species are parasites and cause diseases of the skin, ear
and respiratory organs of higher animals including man.
 The generic name Aspergillus was given to the conidial stage of the fungus
long ascospores were found, and this name still survives in the name of the
family

5. Vegetative Structure
 The vegetative body is a much-branched mycelium consisting of usually
colourless, septate hyphae. It ramifies in or on the surface of the substratum, or
through the intercellular space of the host tissue. Each hyphal cell contains
granulate, vacuolated and multinucleate protoplasm with oil globules as food
reserves. I t contain stipe, foot cells, sterigma which contain conidia.

6. Vegetative body

7. Reproduction
 Eurotium reproduce by
 Asexual reproduction
 Sexual reproduction

8. Asexual Reproduction
 . During asexual reproduction numerous straight, thick-walled, aseptate and
upright hyphae shoot up in the air. These are called conidiophores. The free end
of each conidiophore swells up and usually becomes spherical forming a
vesicle. This vesicle buds out a large number of peg-like outgrowths, called
sterigmata.
 From the tip of each sterigma spherical or nearly spherical, smooth or
roughened conidia are cut off in basepetal succession, the youngest conida
remain in contact with the sterigmata, while the oldest ones are farthest away
from them. The cytoplasm and nuclei stream up the conidiophore into the
sterigmata and finally into the developing conidia. The number of nuclei in
each conidium is variable and it varies from species to species.
 Usually, it is multinucleate, but some rare cases there may be one nucleus in
each conidium. The conidia, as they are formed, are not separated from one
another for the time being, but they remain in rows or chains on the sterigmata
till they become ripe.
 They are produced in enormous quantities and at maturity become deciduous,
and are readily carried away by the wind. Each conidium, under favourable
conditions, germinates on a suitable substratum and produces a mycelium
directly.

9. Sexual Reproduction
 Sexual reproduction of Eurotium will be described here for the best
known species E. herbariorum (= Aspergillus herbariorum). In the
species the same mycelium, producing the conidia, eventually bears the
sex organs.
 The female branch, or the archicarp, is a specialized hypha, which
becomes coiled, at first loosely but later on very closely, in a helix. This
archicarp, at first one-celled, is soon divided into several multinucleate
cells. At this stage, it becomes differentiated into three portions- a
multicellular stalk, a unicellular oogonium, and a terminal unicellular
trichogyne.
 After the differentiation of the archicarp, there appears another septate
hypha, from the tip of which the unicellular, multinucleate antheridium is
cut off. The antheridium develops either independently of the archicarp
on another hypha, or is formed on slender branches arising from
beneath the archicarp.
 After its formation, the antheridium appears to climb up the side of the
coiled archicarp. The union between the antheridium and the archicarp
has not been observed in any case and possibly does not take place.
The antheridium appears to be rudimentary and its nuclei usually
degenerate before it attains the full size. The growth of the antheridium
may even be checked, or the antheridium may not develop at all.

10. Continue….

 However, the oogonium soon becomes septate and forms binucleate cells.
From these binucleate cells small outgrowths develop, which grow and
form branched hyphae, the ascogenous hyphae. From the terminal or sub-
terminal cell of an ascogenous hypha an ascus develops.
 When young, each ascus is binucleate. The two nuclei fuse to form a fusion
nucleus. It undergoes three divisions, in one of which reduction in
chromosome number takes place, forming eight daughter nuclei, around
which ascospores are delimited.
 The cytoplasm, which is not used up in the formation of ascospores,
constitutes the epiplasm containing food substances, especially glycogen.
Each ascospore has a sculptured spore wall (epispore) and is of
characteristic form, and when seen laterally, somewhat resembles a pulley
wheel or a butcher’s tray.

11. Continue…..
 A little before the septation of the oogonium some vegetative
hyphae grow up and cover the sex organs. The hyphae by inter-
weaving and septation form a thick outer wall of small-celled
pseudo-parenchyma which completely encloses the sex organs.
Some of the hyphae grow inwards and form a nutritive tissue
around the sex organ. The entire structure, thus formed, is the
fructification of Eurotium and is termed a cleistothecium.
 The wall of the cleistothecium becomes invested with a brittle-
yellow substance. At maturity, the ascogenous hyphae, the cells of
the nutritive tissue and the walls of the asci disintegrate and are
ultimately absorbed, so that the ascospores lie free within the outer
brittle pseudoparenchymatous sheath of the cleistothecium. This
wall finally decays and the ascospores are set free. Each asccspore,
under favourable conditions, germinates on a suitable substratum
and produces a new mycelium.

12. Life cycle