This document summarizes the systematic position and life cycle of the fungus Penicillium. It notes that Penicillium is classified as Ascomycetes, order Eurotiales, family Eurotiaceae. The vegetative body is a mycelium composed of branched, septate hyphae. Penicillium reproduces through vegetative, asexual, and sexual means. Sexual reproduction involves the formation of ascocarps containing asci with ascospores, which germinate to form new mycelia. The life cycle is completed through both asexual spore formation and the sexual cycle involving ascogonium, antheridium, and cleistothecium formation.

1. Systematic position and life cycle of
Penicillium
Sankrita Gaonkar
Assistant Professor in Botany
sankrita002@gmail.com

2. Contents
• Systematic position of Penicllium
• Life cycle of Penicillium
• Reference

3. Penicillium
Systematic position:
• Class: Ascomycetes
• Order: Eurotiales
• Family: Eurotiaceae
• Genus: Penicillium
Penicillium

4. General features:
• The vegetative body is mycelial
• The mycelium is profusely branched with septate hyphae, composed of thin-
walled cells containing one to many nuclei
• Each septum has a central pore, through which cytoplasmic continuity is
maintained.
• The reserve food is present in the form of oil globules.
• Penicillium is a saprophytic fungus, commonly known as blue or green
mold.
• Genus includes approx. 136 species, distributed throughout the world.
• They are present in soil, in air, on decaying fruits, vegetables, meat, etc.
• Penicillium fungi are microscopic organisms that are used in the production
of foods and in the pharmaceutical industry.

7. Reproduction:
• Vegetative, asexual and sexual means.
• Vegetative reproduction: takes place by
breaking of vegetative mycelium into
two or more fragments. Each fragment
then grows individually like the mother
mycelium.
• Asexual reproduction: unicellular,
uninucleate, nonmotile spores, the
conidia; formed on conidiophore.
Conidiophore develops as an erect
branch from any cell of the vegetative
mycelium.

8. Sexual reproduction: ascospores
• Isogamy or Oogamy (ascogonium- female, antheridium – male)
• The ascogonium develops from any cell of the vegetative filament as an
erect uninucleate and unicellular body (Fig. E). The nucleus then
undergoes repeated mitotic divisions and produce many nuclei.
• The antheridium develops with ascogonium from any neighbouring hypha
(Fig. F). It is also an uninucleate and unicellular branch which coils
around the ascogonium. The apical region of antheridial branch cuts off
by septum and forms a short, somewhat inflated unicellular and
uninucleate antheridium (Fig. G).
• After maturation of both ascogonium and antheridium, the tip of the
antheridium bends and touches the ascogonial wall. The common wall at
the point of contact dissolves and the two cytoplasm then intermixed.
Life cycle

9. • The nucleus of the .antheridium does not migrate (Fig. H) into the
ascogonium. Later, the pairing of nuclei into the ascogonium takes
place by the ascogonial nuclei only. The ascogonium then divides by
partition wall into many binucleate cells, arrange uniseriately (Fig.
H).
• Some of the binucleate cells of the ascogonium projects out by the
formation of multicellular ascogenous branched hyphae, whose cells
are also dikaryotic (Fig. I). The apical cells of the dikaryotic mycelia
swell up and function as an ascus mother cells (Fig. J).
• Both the nuclei of ascus mother cell undergo karyogamy and form
diploid (2n) nucleus (Fig. K). The nucleus then undergoes first
meiosis, then mitosis, results in the formation of 8 nuclei; those after
accumulating some cytoplasm form 8 ascospores (Fig. L).

10. • With the development of ascogonium and antheridium, many sterile
hyphae gradually entangle with them and finally after the formation
of ascospores, the total structure becomes a round fruit body i.e.,
cleistothecium (Fig. M). The asci arrange irregularly inside the
cleistothecium. The ascospores may be globose, elliptical or lenticular
in shape with smooth, echinucleate, pitted (Fig. N)
• The ascospores are released by the dissolution of ascus and
cleistothecium wall. The ascospore germinates on a suitable
substratum by developing germ tube (Fig. O) and ultimately into a
mycelium like the mother.

12. References
• Vashishta B.R., Sinha A.K. and Singh V.P. 2012. Botany for
degree students: Algae. S. Chand & company ltd.