Introduction[8]
Kingdom: Fungi
Phylum: Zygomycota Class: Zygomycetes Order: Mucorales Family: Mucoraceae Genus: Rhizopus Species: R. stolonifer |
R. stolonifer, commonly known as black bread mold, is a saprophytic zygomycete that feeds on bread, jams, pickles, cheese, and other moist food. It is clearly visible on contaminated substrates, and due to having black sporangia, black spores, and black mycelium, appears black. Distribution is worldwide. The mycelium is composed of aseptate hyphae[1], and anchored into the substrate by rhizoids. It is also the cause of a rare human infection, zygomycosis, and a wide range of plant diseases.
Right: R. stolonifer mycelium after germination
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Life cycle[9]
Asexual reproduction is the norm among R. stolonifer. The mycelium is haploid, and haploid spores are produced by mitosis from the sporangia, which grow out of the tips of individual hyphae[1]. If environmental conditions are harsh, or food supply is low, R. stolonifer may reproduce sexually instead (presumably because it would need to produce fewer spores when they have more genetic variation, hence using up less energy?)[1]. This entails two hyphae meeting. Hyphae will release pheremones and detect eachother chemically and grow towards eachother. If the two hypae are of opposite mating types, they'll undergo karyogamy and develop a diploid zygospore. The zygospore spawns a sporangium that mitotically produces hapoid spores to develop new mycelia.
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References
[1]Campbell & Reece, Biology 8th Edition
[8]http://eol.org/pages/2944808/overview
[9]Mader, S., Biology 7th Edition
[8]http://eol.org/pages/2944808/overview
[9]Mader, S., Biology 7th Edition