Relic DNA is abundant in soil and obscures estimates of soil microbial diversity

Examination of soils using viability PCR based on the photoreactive DNA-intercalating dye propidium monoazide found that, on average, 40% of both prokaryotic and fungal DNA was extracellular or from cells that were no longer intact, implying that this ‘relic DNA’ remaining in soil after cell death can obscure treatment effects, spatiotemporal patterns and relationships between microbial taxa and environmental conditions.