Fig. 3

Comparison of HT-qPCR and 16S rRNA gene amplicon sequencing (NGS). A Logarithmic HT-qPCR data (y-axis) and logarithmic count data corresponding to the NGS approach (x-axis). The red line depicts the threshold of 800 copies/μl used for the HT-qPCR data analysis. Shared positive: Measurements obtained with both methods. qPCR only/NGS only: Measurements obtained solely by one of the two methods, HT-qPCR or NGS, respectively. NGS exclusive: Measurements of taxa by NGS for which no HT-qPCR assay was available. The number of observations for each group is given in brackets. B Direct comparison of the relative abundance data of HT-qPCR (copies/μl) on the y-axis and NGS (reads) on the x-axis. The taxa that were exclusively detected by NGS (NGS exclusive) were not considered. C Plot of the bias point estimates ± two geometric standard errors calculated for the NGS approach using the HT-qPCR approach as a reference method. Only the data of the shared positive measurements were used for the bias estimation