Black bread mold
|Black bread mold|
(Ehrenb.: Fr.) Vuill.
Rhizopus stolonifer (black bread mold) is a widely distributed thread-like Mucoralean mold. Commonly found on bread surfaces, it takes food and nutrients from the bread and causes damage to the surface where it lives.
Asexual spores are formed within pinhead-like sporangia, which break to release the spores when mature. Germination of these spores forms the haploid hyphae of a new mycelium. R. stolonifer grows rapidly at temperatures between 15 and 30°C.
Rhizopus stolonifer is a heterothallic species (Schipper 1984), in that sexual reproduction happens only when opposite mating types (designated + and -) come in contact. Successful mating results in the formation of durable zygospores at the point of contact. Subsequently, the zygospore germinates and forms a sporangiophore whose sporangium contains both + and - haploid spores. There are two varieties: R. stolonifer var. stolonifer produces straight, erect sporangiophores, whereas those of R. stolonifer var. lyococcos are curved. A closely related species, Rhizopus sexualis, differs primarily in being homothallic (self-compatible).
Distribution and habitat
Rhizopus stolonifer has a cosmopolitan distribution. It is capable of causing opportunistic infections of humans (zygomycosis). It is most commonly found growing on bread and soft fruits such as bananas and grapes. Because its spores are common in the air, it can often be grown within a few days by keeping moistened pieces of bread in an enclosed, humid environment.
- Schipper, M. A. A. 1984. A revision of the genus Rhizopus. I. The Rh. stolonifer-group and Rh. oryzae. CBS Studies in Mycology 25:1-19.
- Time lapse video of Rhizopus stolonifer attacking strawberries at the Cornell Mushroom Blog.
- An Informative, Heart-Warming Tale about Black Bread Mold General information, diagrams, growth video.