Rhizopus arrhizus is a fungus of the family Mucoraceae

Mucoraceae

The Mucoraceae are a family of fungi of the order Mucorales, characterized by having the thallus not segmented or ramified. Pathogenic genera include Absidia, Apophysomyces, Mucor, Rhizomucor, and Rhizopus. According to a 2008 estimate, the family contains 25 genera and 129...

, characterized by sporangiophores that arise from nodes at the point where the rhizoids are formed and by a hemispherical columella

Columella

Lucius Junius Moderatus Columella is the most important writer on agriculture of the Roman empire. Little is known of his life. He was probably born in Gades , possibly of Roman parents. After a career in the army , he took up farming...

. It is the most common cause of mucormycosis

Mucormycosis

Zygomycosis is the broadest term to refer to infections caused by bread mold fungi of the zygomycota phylum. However, because zygomycota has been identified as polyphyletic, and is not included in modern fungal classification systems, the diseases that Zygomycosis can refer to are better called by...

 in humans and occasionally infects other animals.

Rhizopus arrhizus spores contain ribosomes as a spore ultrastructure.

Metabolism in the fungus changes from aerobic

Aerobic

Aerobic is a word that means "requiring air", where "air" usually means oxygen.Aerobic may also refer to:* Aerobic exercise, prolonged exercise of moderate intensity* Aerobics, a form of aerobic exercise...

 to fermentation

Fermentation (biochemistry)

Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...

at various points in its life cycle.