Fig. 2

Overview of data (pre-)processing. Samples were quantified by fluorometry and quantitative PCR after DNA extraction (upper panel) and library preparation (lower panel) (A). Sequence length histograms were generated after quality control and trimming based on subsampled (n = 1million read pairs) data sets. The gray shading highlights three data sets for which the read length distribution was skewed to the left. Based on taxonomic profiling (see main text), we summarized these three data sets in two groups: (1) and (2) (B). The proportion of quality-controlled and trimmed sequences that could be assigned taxonomically was determined based on database queries with diamond against NCBI nr