Penicillium is one of the most common household molds and is a frequent food contaminant. The conidiospores usually appear grey, green, or blue and are produced in chains on finger-like projections called sterigmata . Aspergillus is another common contaminant. Although usually nonpathogenic, it may become opportunistic in the respiratory tract of a compromised host and, in certain foods, can produce mycotoxins. Its conidiospores appear brown to black and are produced in chains on the surface of a ball-like structure called a vesicle .
Rhizopus is an example of a mold that produces sporangiospores.
Although usually nonpathogenic, it sometimes causes opportunistic wound and respiratory infections in the compromised host. Its produces brown or black sporangiospores within sacs called sporangia . Anchoring structures called rhizoids are also produced on the vegetative hyphae. Rhizopus can also reproduce sexually. The dermatophytes are a group of molds that cause superficial mycoses of the hair, skin, and nails and utilize the protein keratin.