Nocardiaceae

The Nocardiaceae are a family of aerobic, non-fastidious, high G+C, Gram-positive actinomycetes that are commonly found in soil and water. Some bacteria from this family are even indigenous to the Antarctic. Nocardiaceae present coccobacilli, filamentous or, rarely, fragmented and palisading forms, and filamentous species grow in a branching morphological pattern similar to fungal hyphae.

Pathogenic capacity
Some species colonize animals, and members of the Nocardia and Rhodococcus genera can cause infection in humans and livestock. Many members of this family integrate mycolic acids into their cell wall, and as a result, Nocardia spp. may be mistaken for mycobacteria when viewed under a microscope following an acid-fast stain.

Wastewater foaming
Nocardia species are often responsible for the accumulation of foam that occurs in activate sludge during wastewater treatment. Biological foaming can be problematic for the water treatment process, and foam accumulation is reduced by adding surfactants to the wastewater.

Bioremediation of hydrocarbons
Soil Nocardiaceae can degrade hydrocarbons (e.g. petroleum distillates) and have been proposed as bioremediation agents for environmental spills.

Nomenclature changes
In the 1980's, all Micropolyspora spp. were transferred to the genera Nocardia, Nonomuraea in family Streptosporangiaceae, or Saccharopolyspora in family Pseudonocardiaceae. This effectively ended the official status of this genus, but the name persists in older research articles.