Fungal partnerships stimulate growth of Termitomyces clypeatus stalk mycelium in vitro.

The symbiotic relationship between termites and Termitomyces fungi, which allows the termite to digest cellulose-rich food sources, is poorly understood. In this study, in vitro mixed symbiotic relationships between Termitomyces clypeatus and fungi isolated from individual fungus-comb communities using a culture-dependent method were analyzed. Twenty-day-old stalk cultures of three T. clypeatus isolates were co-cultured with cellulase-producing fungi on potato dextrose agar. The high cellulase-producing fungal isolate no. 18, which showed 99 % ITS sequence identity to Sordariomycetes endophyte isolate 2171 (EU687039), increased growth of T. clypeatus 18/50 by 85.7 %. The high xylanase-producing isolate no. 13, which showed 88 % ITS sequence identity to Arthrinium sacchari isolate L06 (HQ115662), stimulated T. clypeatus 18/50 growth by 58.6 %. The high cellulase- and xylanase-producing isolate no. 50, which showed 90 % ITS sequence identity to the fungal endophyte isolate 2196 (EU687056), improved T. clypeatus 18/50 growth by 45.7 %. A Gigantropanus sp. promoted the growth of T. clypeatus 18/50 and 20/50 by 45.7 and 44.1 %, respectively, and that of T. clypeatus 19/50 by 10.6 %. These results indicated the most beneficial potential partnership of T. clypeatus might involve cellulase-producing fungi isolated from the same ecological niche. The Gigantropanus sp. is a potential partner of T. clypeatus but is likely to be less common than cellulase-producing fungi isolated from fungus combs owing to the lower host specificity of the Gigantropanus sp. This study provides an interesting method to culture Termitomyces using an in vitro mixed culture method for production of Termitomyces fruiting bodies in the future.