Partnership with both fungi and bacteria can protect Odontotermes obesus fungus gardens against fungal invaders.

Abstract

Fungus-growing termites, like Odontotermes obesus, cultivate Termitomyces as their sole food source on fungus combs which are continuously maintained with foraged plant materials. This necessary augmentation also increases the threat of introducing pathogenic fungi capable of displacing Termitomyces. The magnitude of this threat and how termites prevent pathogens remain largely unknown. This study identifies this pathogenic load by establishing the pan-mycobiota of O. obesus from the fungus comb and termite castes. Furthermore, to maximize the identification of such pathogenic fungi, the mycobiota of the decaying stages of the unattended fungus comb were also assessed. The simultaneous assessment of the microbiota and the mycobiota of these stages identified possible interactions between the fungal and bacterial members of this community. Based on these, we propose a possible interaction among the crop fungus Termitomyces, the weedy fungus Pseudoxylaria and some bacterial mutualists. These possibilities were then tested with in vitro interaction assays which suggest that Termitomyces, Pseudoxylaria and bacterial mutualists all possess anti-fungal capabilities. We propose a multifactorial interaction model of these microbes, under the care of the termites, to explain how their interactions can maintain a predominantly Termitomyces monoculture.