DGGE (a) and UPMGA clustering analysis (b and c) of the Sphingomonadaceae community of the G-soil-derived mycosphere of Laccaria proxima and its corresponding bulk soil (left gel in panel a) and the N-soil-derived mycosphere of Russula exalbicans and its corresponding bulk soil (right gel in panel a) based on 361-bp Sphingomonadaceae-specific 16S rRNA gene fragments. The arrowheads point to the excised bands. Lanes: M, markers: +, 16S rRNA gene fragment of a Sphingomonas echinoides isolate denoted HB44; Myc, mycosphere; Bulk, bulk soil. The scales at the top of panels b and c show percent similarity. The numbers at the nodes indicate the bootstrap value as a percentage (1,000 replications).