Data contain the quantitative polymerase chain reaction (qPCR) numbers of total bacterial and archaeal 16S ribosomal RNA (16S rRNA) genes from 3 different nematode treatments and two different substrates conditions in the natural soil. In first treatment condition there was no addition of nematode, in second treatment bacterivorous nematode (Acrobeloides buetschlii) was added and in third treatment there was the addition of fungivorous nematode (Aphelenchoides saprophilus). Meanwhile, two different substrate conditions were: with and without maize litter. The natural soil for these experiments were collected from Dikopshof agricultural site (50°48′21″ N, 6°59′9″ E), Bonn, Germany. These qPCR numbers were collected in June and July, 2023 to look at the effect of nematode grazing in the bacterial and archaeal populations. The qPCR was performed using primer set of 1389F (5′-TGYACACACCGCCCGT-3′) and 1492R (5′-GGYTACCTTGTTACGACTT-3′) with 20 µl reactions on a qTOWER3G (Analytik-Jena, Jena, Germany).
Metabarcoding has become the workhorse of community ecology. Sequencing a taxonomically informative DNA fragment from environmental samples gives fast access to community composition across taxonomic groups, but it relies on the assumption that the number of sequences for each taxon correlates with its abundance in the sampled community. However, gene copy number varies among and within taxa, and the extent of this variability must therefore be considered when interpreting community composition data derived from environmental sequencing. Here we measured with single-cell qPCR the SSU rDNA gene copy number of 139 specimens of five species of planktonic foraminifera. We found that the average gene copy number varied between of ~4 000 to ~50 000 gene copies between species, and individuals of the same species can carry between ~300 to more than 350 000 gene copies. This variability cannot be explained by differences in cell size and considering all plausible sources of bias, we conclude that this variability likely reflects dynamic genomic processes acting during the life cycle. We used the observed variability to model its impact on metabarcoding and found that the application of a correcting factor at species level may correct the derived relative abundances, provided sufficiently large populations have been sampled.