title: Microbial Mat layer B2
design: Mat samples were fixed in ethanol and stored at -20 C until DNA extraction. DNA was extracted using the Power BiofilmTM DNA Isolation Kit (MoBio, Carlsbad, CA, USA) according to manufacturer s instructions. Duplicate mat subsamples were collected from distant ends of each mat sample. For each duplicate, the collected material was thoroughly mixed prior to DNA purification; several independent purification reactions per duplicate were performed in parallel and then pooled to minimize potential biases due to sample and/or process heterogeneity. DNA libraries for Illumina paired-end sequencing were prepared for each sample without any amplification step