You are what your fungus eats: diet shapes the microbial garden of a fungus-growing ant.

Fungus-growing ants maintain an ectosymbiotic microbial garden, an intertwined mesh of fungal symbiont hyphae and microbiota growing through plant substrates. Here, we investigate how different plant diets influence the garden lignocellulosic profile, and whether the microbiota respond to dietary changes. Colonies of Atta sexdens were provided with four different dietary regimens, varying in fiber composition and nutritional content. Diet changed the garden lignocellulosic profile, also influencing the microbial taxonomic composition. The diet of only leaves enriched the garden in Bacillus and Weissella, while a diet of only fruits/cereals lead to a Carnimonas and Mesoplasma enrichment; diets mixing leaves and fruits/cereals intermittently and alternatively enriched the garden in Bacillus, Mesoplasma, and Weissella. The fungal crop development and the spatial distribution of the microbiota and biofilm also varied according to the diet. Our findings suggest that diet has a pivotal role in determining whether ant colonies function optimally and remain healthy.