Optimization of culturing conditions for leafcutter ant associated, antimicrobial producing Pseudonocardia by adding ants´ cuticular hydrocarbons

The purpose of the present study was to investigate the influence of cultivation parameters on the growth of leafcutter ant associated actinomycete Pseudonocardia sp. These bacteria live in a very specialized symbiosis with the leafcutter ant Acromyrmex octospinosus and fungi of the genus Leucoagaricus. Pseudonocardia are known to produce antibiotics but are very hard to grow as a result of the complexity of their symbiosis. The bacteria were grown on yeast-malt-extract agar and the influence of pH, temperature conditions and the addition of chitin and a cuticular hydrocarbon (CHC) solution specific to leafcutter ants on the growth of Pseudonocardia and other bacteria inhabiting the leafcutter ants´ surface was tested. The best growth rate of Pseudonocardia was achieved by cultivation at 28 °C in a medium with pH 7 supplemented with chitin and CHC solution. Additionally, these conditions inhibited the growth of other competitive bacteria. This is the first report on the optimization of growth media for leafcutter ant associated Pseudonocardia adjusted to the conditions found on the ants´ cuticle.