Central Luzon State University
Science City of Muñoz 3120
Nueva Ecija, Philippines
Instructional Module for the Course
PPATH 3305 - Mycology
Phylum Zygomycota
(The Conjugated Fungi/Bread Molds)
Objectives:
1. Illustrate fungal structures representing the Phylum Zygomycota.
2. Explain the economic importance of each group of Phylum
Zygomycota 3. Explain the development/life cycle of Phylum
Zygomycota
4. Equip with the different genera and structures of Phylum
Zygomycota.
Overview
The phylum Zygomycota consists of two classes, the Zygomycetes and
the Trichomycetes. Within these two classes the sexual process consists of the
fusion of two gametangia to give a resting spore, the zygospore. Whether the
two classes are closely related is not clear. The Trichomycetes, of which about
200 species are known, are obligate parasites that live in the gut of insects and
other arthropods, and will not be considered further. There are about 900
species of Zygomycetes, and members of one order, the Mucorales, are very
widespread and abundant. The Mucorales will now be considered, after which
brief reference will be made to other orders.
Zygomycetes - ~ 867 species in 124 genera, 32 families and 10 orders.
Trichomycetes - 218 species in 55 genera, 6 families and 3 orders.
Five major features serve to characterize the phylum Zygomycota:
1. cell walls composed of a mixture of chitin, chitosan (a poorly- or non
acetylated form of chitin) and polyglucuronic acid;
2. hyphae that typically lack cross walls, so all the nuclei are contained within a
common cytoplasm (a
coenocytic mycelium)
3. the production of a thick-walled resting spore – the zygospore – which if
formed by a sexual process involving the fusion of two gametangia; 4. the
production of asexual spores by cytoplasmic cleavage within a sporangium;
5. a haploid genome.
Other Characters
■ No motile cells
■ Hyphae without septa
■ Cell walls contain chitin
■ Asexual spores formed in sporangia (except Trichomycetes)
■ Sexual spore (zygospore) formed by gametangial fusion
■ Life cycle is haploid with restricted diploid
A little History…
∙ 1818 - Christian Gottfried Ehrenberg named a new genus (a fungus he found
, growing on the cap of Agaricus aurantius) as Syzgites megalocarpus. ∙ 1820 -
Ehrenberg described the stages by which conjugation of 2 filaments occurred and a
black fruit body was formed. He regarded this as a sexual process similar to the one
that occurred in the alga, Spirogyra.
∙ 1864-81 - de Bary (deBary & Woronin) re-examined S. megalocarpus and
emphasized the sexual nature of the conjugation and named the fusion spore a
zygospore (zygos = yoke, spora = seed; spore).
∙ Two years later, they described the zygospore in Rhizopus stolonifera.
Ecology
∙ Saprobes of dead plant and animal material, mostly in terrestrial habitats
although they can be isolated from water.
∙ Some pathogenic species on humans and other animals, especially
invertebrates and others in plants
∙ Some species symbiotic with invertebrates or plants.
∙ Several commercially important species.
Sexual Reproduction
∙ Sexual Reproduction: by production of zygospores (thick-walled resting
spores) within zygosporangia that are formed by fusion of gametangia
Science City of Muñoz 3120
Nueva Ecija, Philippines
Instructional Module for the Course
PPATH 3305 - Mycology
Phylum Zygomycota
(The Conjugated Fungi/Bread Molds)
Objectives:
1. Illustrate fungal structures representing the Phylum Zygomycota.
2. Explain the economic importance of each group of Phylum
Zygomycota 3. Explain the development/life cycle of Phylum
Zygomycota
4. Equip with the different genera and structures of Phylum
Zygomycota.
Overview
The phylum Zygomycota consists of two classes, the Zygomycetes and
the Trichomycetes. Within these two classes the sexual process consists of the
fusion of two gametangia to give a resting spore, the zygospore. Whether the
two classes are closely related is not clear. The Trichomycetes, of which about
200 species are known, are obligate parasites that live in the gut of insects and
other arthropods, and will not be considered further. There are about 900
species of Zygomycetes, and members of one order, the Mucorales, are very
widespread and abundant. The Mucorales will now be considered, after which
brief reference will be made to other orders.
Zygomycetes - ~ 867 species in 124 genera, 32 families and 10 orders.
Trichomycetes - 218 species in 55 genera, 6 families and 3 orders.
Five major features serve to characterize the phylum Zygomycota:
1. cell walls composed of a mixture of chitin, chitosan (a poorly- or non
acetylated form of chitin) and polyglucuronic acid;
2. hyphae that typically lack cross walls, so all the nuclei are contained within a
common cytoplasm (a
coenocytic mycelium)
3. the production of a thick-walled resting spore – the zygospore – which if
formed by a sexual process involving the fusion of two gametangia; 4. the
production of asexual spores by cytoplasmic cleavage within a sporangium;
5. a haploid genome.
Other Characters
■ No motile cells
■ Hyphae without septa
■ Cell walls contain chitin
■ Asexual spores formed in sporangia (except Trichomycetes)
■ Sexual spore (zygospore) formed by gametangial fusion
■ Life cycle is haploid with restricted diploid
A little History…
∙ 1818 - Christian Gottfried Ehrenberg named a new genus (a fungus he found
, growing on the cap of Agaricus aurantius) as Syzgites megalocarpus. ∙ 1820 -
Ehrenberg described the stages by which conjugation of 2 filaments occurred and a
black fruit body was formed. He regarded this as a sexual process similar to the one
that occurred in the alga, Spirogyra.
∙ 1864-81 - de Bary (deBary & Woronin) re-examined S. megalocarpus and
emphasized the sexual nature of the conjugation and named the fusion spore a
zygospore (zygos = yoke, spora = seed; spore).
∙ Two years later, they described the zygospore in Rhizopus stolonifera.
Ecology
∙ Saprobes of dead plant and animal material, mostly in terrestrial habitats
although they can be isolated from water.
∙ Some pathogenic species on humans and other animals, especially
invertebrates and others in plants
∙ Some species symbiotic with invertebrates or plants.
∙ Several commercially important species.
Sexual Reproduction
∙ Sexual Reproduction: by production of zygospores (thick-walled resting
spores) within zygosporangia that are formed by fusion of gametangia
