Bacterial strains within the fungus gardens of leaf-cutter ants show evidence of mutual and commensal interactions

Abstract

Leaf-cutter ants have a symbiotic relationship with a fungal cultivar known as Lecuoagaricus gongylophorus. The cultivar functions as an external gut by breaking down plant polysaccharides and supplies the ants with simple sugars. A consistent community of bacteria lives in consortium with this fungus, and the community composition is conserved across ant species. However, the exact role of these bacteria remains uncertain. We carried out several experiments to examine possible roles of the bacterial community. One experiment involved using antibiotic infused-leaf discs to attempt to reduce bacterial abundance within fungus gardens. The other experiment involved growing pure isolates of bacteria from L. gonglyophorus alongside the fungal culture. Conflicting results were obtained from both experiments, so genus level bacterial primers were designed to evaluate bacterial abundance within antibiotic treated fungus gardens. These investigations will provide insight into how the bacterial community interplays with the rest of the leaf-cutter ant system.