RT Journal Article SR Electronic T1 Relic DNA contributes minimally to estimates of microbial diversity JF bioRxiv FD Cold Spring Harbor Laboratory SP 131284 DO 10.1101/131284 A1 JT Lennon A1 SA Placella A1 ME Muscarella YR 2017 UL http://biorxiv.org/content/early/2017/04/26/131284.abstract AB Extracellular or “relic” DNA is one of the largest pools of nucleic acids in the biosphere 1,2. Relic DNA can influence a number of important ecological and evolutionary processes, but it may also bias estimates of microbial abundance and diversity, which has implications for understanding environmental, engineered, and host-associated ecosystems. We developed theoretical predictions from a simulation model based on sampling a species abundance distribution to assess how and when relic DNA biases estimates of microbial diversity. We then tested our predictions by quantifying relic DNA and assessing its contribution to bacterial diversity using 16S rRNA gene sequences collected from soil, sediment, water, and mammalian gut environments. On average, relic DNA made up 33 % of the total bacterial DNA pool, but exceeded 80 % in some samples. Despite its abundance, relic DNA had a minimal effect on estimates of taxonomic and phylogenetic diversity, which is consistent with model simulations where the processes regulating the compositional turnover of relic and intact DNA are at steady state. When such conditions are met, relic DNA should not bias cultivation-independent estimates of microbial diversity.