library_construction_protocol: The preparation of PCR products for pyrosequencing was based on a procedure modified from that described by Berry, et al. Regions V4-V6 of the 16S rRNA gene were amplified with primers 515-530 forward, 5-GTGCCAGCMGCNGCGG-3, and 1068-1052 reverse, 5-CTGRCGRCRRCCATGCA-3. Proportional amounts of each amplicon were mixed and then unidirectionally sequenced from the forward primer using the GS FLX Titanium chemistry followed by amplicons analysis of signal processing (Roche) at the Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic.