FIGURE 2.

Large variability in coverage of universal bacterial 16S rRNA gene primer pairs for HCB taxa. Histograms are shown of coverage for primer pairs designed to produce amplicons of either small (100-400 bp; 105 primer pairs), medium (>400–<1000 bp; 252 primer pairs), or large (>1000 bp; 92 primer pairs) size. The y-axis of the histograms shows the number of primer pairs identified for each interval of coverage, which has been divided into intervals of 10%. Coverage is shown for each target taxon separately to illustrate the variability between coverage across target taxa. Many primer pairs in each of the amplicon size ranges have <10% coverage for at least one target taxa. Primer pairs were identified with >90% coverage for at least one target taxon for all amplicon size ranges, though no large amplicon primer pairs captured the taxa Alcanivorax, Cycloclasticus, or Oleispira with >90% coverage. Details for each primer pair are given in Supplementary Table S1.