design: Bacterial community sequencing of the 16S rRNA gene (v4-v6 region). Amplicon libraries were sequenced on a 454 GSFLX using Titanium chemistry. Quality control and processing were performed as per (Huse et al. 2007 "Accuracy and quality of massively parallel DNA pyrosequencing." Genome Biol 8:R143, doi:10.1186/gb-2007-8-7-r143). More details can be found via VAMPS web site and documentation (Huse et al. 2014 "VAMPS: a website for visualization and analysis of microbial population structures." BMC Bioinformatics 15: 41. doi:10.1186/1471-2105-15-41)