Dynamics of extracellular DNA decomposition and bacterial community composition in soil

Microbial rRNA:rDNA gene ratios may be unexpectedly low due to extracellular DNA preservation in soils

“…As extracellular microbial DNA is likely to be released in close proximity to clay particles (Miltner et al, 2012) or within macro-or microaggregates (Blaud et al, 2012), it may be even more protected than laboratory studies using additions of pure DNA or bacterial inoculum would otherwise suggest (Schimel and Schaeffer, 2012). Although an extensive literature exists to support the stabilization of DNA in soil and sediment (Corinaldesi et al, 2008;Ceccherini et al, 2009;Alawi et al, 2014;Morrissey et al, 2015), this has largely been ignored in DNA based microbial ecology studies.…”

“…Their distinctive cell wall adaptations may give them an increased ability to adapt to prolonged, harsh conditions. Alternately, it was recently shown that abundances of Planctomycetes increased in abundance in soils to which 13 C-labeled eDNA had been added, suggesting that some members of this group may be adapted to use eDNA to fuel their own growth (Morrissey et al, 2015).…”

Extracellular DNA in natural environments: features, relevance and applications

“…Accounting for over 10% of the extractable P in soil and containing essential elements such as N and C, exDNA may act as a nutrient and energy source especially in soils with low nutrient input (reviewed by Levy-Booth et al 2007; Nielsen et al 2007). After a breakdown by extracellular and cell-associated nucleases (DNases), smaller exDNA molecules are taken up by microbial cells, where they either serve as building blocks for newly synthetized nucleic acids or are further broken down to essential nutrients (Morrissey et al 2015). …”

Cell-Free DNA: An Underestimated Source of Antibiotic Resistance Gene Dissemination at the Interface Between Human Activities and Downstream Environments in the Context of Wastewater Reuse

“…A limiting factor for efficient transformation is the availability of free exDNA (Nielsen and Van Elsas, 2019). However, the situation is unclear as fragments of exDNA show long-term persistence (several years) in soil and other natural environments (Overballe-Petersen et al, 2013), and despite adsorption to soil particles exDNA is capable to transform competent cells in these environments (Romanowski et al, 1993;Thomas and Nielsen, 2005;Morrissey et al, 2015). HGT by natural bacterial transformation in soils is assumed as an infrequent process (Nielsen et al, 1998;Pietramellara et al, 2006;Pietramellara et al, 2007).…”