Comment on Bohmann et al. Strategies for sample labelling and library preparation in DNA metabarcoding studies

DNA metabarcoding necessitates labelling amplicons in order to connect sequencing reads with samples, but labelling protocols may cause errors where indexes are incorrectly assembled during PCR due to tag-jumping. A recent paper by Bohmann et al (2021) reviews the main labelling methods and point out that library building using PCR’s on tagged amplicons may be particularly problematic. Due to unforeseen problems in two sequencing projects, we had to use a second PCR on tagged amplicons to salvage two large data sets. This test showed that the problems with tag-jumping errors were acceptable and could be accounted for during analysis, if handled properly when designing the indexing strategy.