Abstract
Pseudonocardia species comprise a genus of filamentous, sporulating bacteria belonging to the phylum Actinomycetota, formerly Actinobacteria. They are found in marine and freshwater sediments and soils and associated with marine animals, insects, and plants. To date, they have mostly been studied because of their mutually beneficial symbiosis with fungus-growing ants in the tribe Attini. They have also attracted interest due to their biosynthetic capabilities, including the production of variably glycosylated polyenes and other novel antifungal compounds, and for their capacity to grow on a variety of hydrocarbons. The majority of clinically used antibiotics are derived from the specialised metabolites of filamentous actinomycete bacteria and most of these come from the genus Streptomyces. However, in the quest for novel chemistry there is increasing interest in studying other filamentous actinomycete genera, including Pseudonocardia. Here we outline the biological properties, genome size and structure and key features of the genus Pseudonocardia, namely their specialised metabolites and ecological roles.