Persistence of DNA studied in different ex vivo and in vivo rat models simulating the human gut situation

In vivo transfer of plasmid from food-grade transiting lactococci to murine epithelial cells

“…23 Thus, we considered that 72 h after the last gavage, most of lactococci administered have been lysed and eliminated suggesting that the BLG cDNA detected at this time is probably located in either the intestinal lumen or inside the epithelial membrane rather than in lactococci. Considering the short half-life of naked DNA in the small intestine, 24 most of BLG cDNA detected is probably inside the murine epithelial cells. The question of how DNA plasmid entered epithelial membrane cells is raised and no clear answers are available at this time.…”

Lack of detectable DNA uptake by bacterial gut isolates grownin vitroand byAcinetobacter baylyicolonizing rodentsin vivo

“…The sharply reduced DNA uptake frequencies also observed in the presence of sterile gut material from mice indicate that microbially produced DNA nucleases are not responsible for the absence of observable transformation. Bacterial nucleases have also in other studies been found to play a minor role in DNA degradation (Maturin and Curtiss, 1977;Wilcks et al, 2004). Wilcks et al (2004) showed that plasmid DNA isolated from intestinal compartments from mono-associated rats can remain biological active (in electroporation assays of E. coli) after purification.…”

“…Bacterial nucleases have also in other studies been found to play a minor role in DNA degradation (Maturin and Curtiss, 1977;Wilcks et al, 2004). Wilcks et al (2004) showed that plasmid DNA isolated from intestinal compartments from mono-associated rats can remain biological active (in electroporation assays of E. coli) after purification. Thus, a possible explanation for the sharp ∼1 000 000-fold reduction of transformation frequencies in the presence of gut contents can be a reversible binding of DNA to feed surfaces and macromolecules that renders DNA inaccessible to competent bacteria.…”

“…It has been estimated that humans digest 0.1 to 1 mg DNA per day (Doerfler, 2000). Whereas the majority of feed-derived DNA is broken down during digestion (Martín-Orúe et al, 2002;Palka-Santini et al, 2003;Tony et al, 2003), several studies have now shown that minor proportions of feed-derived DNA survive immedi-ate degradation and reach the bloodstream in various animals (Deaville and Maddison, 2005;Einspanier et al, 2001;Jennings et al, 2002;Schubbert et al, 1994;1998) or are detectable as minor fragments in faeces (Chowdhury et al, 2003a;2003b;Wilcks et al, 2004). The fate of chromosomal DNA in the gastrointestinal tract (GIT) of humans and animals has recently received increased attention due to the introduction of novel ingredients derived from genetically modified organisms (GMOs) in the food chain (Sharma et al, 2004;.…”

“…For instance, it has been reported that the naturally competent Streptococcus gordonii DL1 could be transformed by plasmid DNA in saliva (Mercer et al, 1999b;. Other studies examining in vivo transfer in gut samples from different mice and rat models have not been able to detect bacterial transformants (Kharazmi et al, 2003;Wilcks et al, 2004). One DNA consumption study in humans (including ileostomists; individuals in which the terminal ileum is resected and the digesta is diverted via a stoma to a colostomy bag) indicated that horizontal transfer of recombinant DNA from GM soya to the microbiota of the small bowel had taken place in the past.…”