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A nitrifier-enriched microbial community contributes to the degradation of environmental DNA

September 5, 2023

Environmental DNA (eDNA) surveys are a promising alternative to traditional monitoring of invasive species, rare species, and biodiversity. Detecting organism-specific eDNA reduces the need to collect physical specimens for population estimates, and the high sensitivity of eDNA assays may improve detection of rare or cryptic species. However, correlating estimated concentrations of eDNA with species abundance can be difficult due to the many abiotic and biotic factors that influence eDNA persistence and degradation. Here, we assessed the impact of a nitrifier-enriched microbial (NEM) community on the persistence and degradation of Hypophthalmichthys molitrix (silver carp) milt eDNA using experimental aquatic mesocosms and a quantitative PCR approach. The NEM community was cultured from combined sediment and water samples collected from a golf course pond in Columbia, Missouri (USA), and experiments were conducted in the dark at 22°C. We found that the NEM community transformed organic nitrogen from silver carp milt to measurable amounts of nitrate, both in the presence and absence of ammonia nitrogen. Additionally, regardless of ammonia availability, milt eDNA followed a one-phase exponential decay pattern after an initial 24-h plateau in the presence of the NEM community. However, milt eDNA had a shorter half-life (12.5 h) in the absence of exogenous ammonia compared to when ammonia was present (15 h). In sterile mesocosms, eDNA was stable during the 72-h experiment. Together, these results suggest that the presence of microorganisms is necessary for short-term degradation of eDNA. Furthermore, nitrifying microbial communities, which are ubiquitous in most soil and water environments, could limit eDNA persistence in the environment. Understanding the contributions of environmental microbial communities will allow more confidence in sampling design and eDNA result interpretations for biodiversity management applications.

Publication Year 2023
Title A nitrifier-enriched microbial community contributes to the degradation of environmental DNA
DOI 10.1002/edn3.469
Authors Rachelle Elaine Beattie, Caren C. Helbing, Jacob J. Imbery, Katy E. Klymus, Jonathan Lopez Duran, Cathy A. Richter, Anita A. Thambirajah, Nathan Thompson, Thea Margaret Edwards
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental DNA
Index ID 70248078
Record Source USGS Publications Warehouse
USGS Organization Columbia Environmental Research Center