Here, I would make the link to metagenome/metatranscriptome analyses, which also provide hints to absolute abundances or cross-kingdom comparisons, without PCR amplification bias. maybe also mention meta-proteome profiling, although it still suffers childhood diseases such as high costs and low throughput, but can provide other independent insights, not based on nucleic acids (some new literature on that: doi: 10.3390/microorganisms8111694 , doi. 10.1016/j.jprot.2020.103791, doi 10.1016/j.apsoil.2019.103480 ).
The influence of relic or exogenous DNA on investigations of microbial community composition has recently been explored (15, 19, 20).