Rhizopus stolonifer- Black Bread Mold

Figure 17: Black Bread Mold; Magnification 40x  

Figure 18: Structure of Rhizopus stolonifer

Taxonomic Classification:

Domain: Eukarya

Kingdom: Fungi

Phylum: Zygomycota

Class: Zygomycetes

Order: Mucorales

Family: Mucoracaea

Genus: Rhizopus

Species: Rhizopus stolonifer [45]

 Why does the organism belong in this Domain?

            The Black Bread Mold is a Eukaryotic organism. It can be inferred to be Eukarya because this organism is able to reproduce sexually, which prokaryotes can’t.  [45] Furthermore, Rhizopus stolonifera is multicellular. [59] These two characteristics can only be classified in the Domain Eukarya and not Domain Archaea or Bacteria. Rhizopus stolonifera is saprotrophic. This means this organism lives and consumes its nutrients by dead organic matter. Even when the Rhizopus stolonifera begins to produce mold on the substance, it will continue to grow and spread because it is saprotrophic. In addition to being saprotrophic, the organism is also considered a parasite. This is because it consumes the nutrients from fruit or other foods and does not give the substance anything in return. [46] In the kingdom Fungi, the organisms could have multiple modes of nutrition. The most evident characteristic is  the saprotrophs, which use dead organic material to become their energy source. [5] In addition, this organism is not motile and is only able to spread via spores. [45] Indeed, this is the only possible movement of an organism is the kingdom Fungi. [6] Also, the organism reproduces sexually by zygospores or asexually by uni/multi-spored sporangia. In sexual reproduction, two different strains have their hyphal tips which become intertwined. Through a whole process and then meiosis, zygospores are finally created.  However, in asexual reproduction, sporangiospores are formed. [45] Producing asexual or sexual are both characteristics that are found in organisms in the kingdom Fungi. [7] Since this organism is clearly classified in the Kingdom Fungi, it must be categorized in the Domain Eukarya.

General Explanation:

           Rhizopus stolonifera is also known as the black bread mold. This type of mold is one of the most common mold species. The black bread mold depends on sugar and starch from certain foods like bread and soft fruits. This is how the organism will be able to grow, mature, obtain nutrition, and help in reproduction. . The sugar and starch is the energy source for the organism. Even though the Black Bread Mold lives in moist substances like fruit, because it helps it spread, this organism also likes dry environments. These habitats include, soil, fresh decaying litter, wild bird nests, and even children's sandboxes. The optimal growth temperature for the Rhizopus stolonifera is 15°C-30°C.  This temperature is where the spores are able to germinate and mature. [46] The organism reproduces asexually and sexually. When the sporangia matures, the color turns from white to black.  The organism itself is unable to move, however the spores it produces asexually are carried away by the wind.

            Due to the abundance and common presence of Rhizopus stolonifer spores in the air, the mold has the ability to quickly form on any surface in which it can obtain food. The spores that are produced through reproduction are commonly found in the air, also, in moist environments, such as bread, Rhizopus stolonifer can quickly spread within a few days. The black bread mold causes fruits to rot, and can even cause human infections. They take the nutrients, and substrates of enzymes from the fruit and other foods.  This organism can be considered important because of the function it obtains in the carbon cycle. It acts as a decomposer in the soil, and in many foods. [45]

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