From ActinoBase

Pseudonocardia are filamentous actinomycetes with ~6Mbp circular genomes, best known as vertically transmitted mutualists of fungus-growing attine ants. Leafcutter ant associated strains make polyene antifungals that are variants of nystatin A1, with additional hexose sugar groups. Less highly evolved attine ants are associated with Pseudonocardia strains that make depsipeptide antibiotics such as dentigerumycin. These organisms are generally slow growing and often only grow on agar plates. They are also difficult to genetically manipulate although they are amenable to conjugation from E. coli and mutations have been made using suicide vectors.


Image shows colonies of two different Pseudonocardia strains growing on agar plates and on the propleural plate of an Acromyrmex echinatior leafcutter ant (the white covering on the chest area).

Further reading:

Heine D, Holmes NA, Worsley SF, Santos ACA, Innocent TM, Scherlach K, Patrick EH, Yu DW, Murrell JC, Vieria PC, Boomsma JJ, Hertweck C, Hutchings MI and Wilkinson B (2018). Chemical warfare between leafcutter ant symbionts and a co-evolved pathogen. Nature Communications

Li H, Sosa-Calvo J, Horn HA, Pupo MT, Clardy J, Rabeling C, Schultz TR and Currie CR (2018). Convergent evolution of complex structures for ant–bacterial defensive symbiosis in fungus-farming ants. PNAS 115:10720-10725;

Holmes N, Innocent T, Heine D, Worsley S, Findlay K, Murrell J.C., Wilkinson B, Boomsma JJ and Hutchings MI (2016). Genome analysis of two Pseudonocardia phylotypes associated with Acromyrmex leafcutter ants reveals their biosynthetic potential. Front Microbiol. 7:2073.

Andersen SB, Hansen LH, Sapountzis P, Sørensen SJ and Boomsma JJ (2013). Specificity and stability of the Acromyrmex-Pseudonocardia symbiosis. Molecular Ecology 22:4307-4321.

Oh DC, Poulsen M, Currie CR and Clardy J (2009). Dentigerumycin: a bacterial mediator of an ant-fungus symbiosis. Nature Chemical Biology 5:391-3.