Fig. 5

Synthetic non-biological 16S DNA as a positive control for 16S rRNA marker gene sequencing. a A diagram of the gene block design. At the top is a typical 16S rRNA gene amplicon, with primer binding sites for the widely used 27F and 338R primers. To generate recognizable sequences that would not be found authentically in samples, synthesized DNAs with the forward (27F) and reverse (338R) primer landing sites added to Archaeal DNA sequences, creating molecules not found in nature but readily analyzed using conventional pipelines. b Control sequence mixtures using the gene blocks show consistent relative abundances. Note that the eight gene blocks annotate as five archaeal taxa. c Heat map displaying the relative abundance of control gene blocks, where each square represents one well on a 96-well plate of a typical 16S rRNA marker gene sequencing project. Positive control wells where gene block was added and amplified alongside experimental samples are denoted with “x”