An investigation of horizontal transfer of feed introduced DNA to the aerobic microbiota of the gastrointestinal tract of rats

BACKGROUND:

Horizontal gene transfer through natural transformation of members of the microbiota of the lower gastrointestinal tract (GIT) of mammals has not yet been described. Insufficient DNA sequence similarity fo
BACKGROUND:

Horizontal gene transfer through natural transformation of members of the microbiota of the lower gastrointestinal tract (GIT) of mammals has not yet been described. Insufficient DNA sequence similarity for homologous recombination to occur has been identified as the major barrier to interspecies transfer of chromosomal DNA in bacteria. In this study we determined if regions of high DNA similarity between the genomes of the indigenous bacteria in the GIT of rats and feed introduced DNA could lead to homologous recombination and acquisition of antibiotic resistance genes.
RESULTS:

Plasmid DNA with two resistance genes (nptI and aadA) and regions of high DNA similarity to 16S rRNA and 23S rRNA genes present in a broad range of bacterial species present in the GIT, were constructed and added to standard rat feed. Six rats, with a normal microbiota, were fed DNA containing pellets daily over four days before sampling of the microbiota from the different GI compartments (stomach, small intestine, cecum and colon). In addition, two rats were included as negative controls. Antibiotic resistant colonies growing on selective media were screened for recombination with feed introduced DNA by PCR targeting unique sites in the putatively recombined regions. No transformants were identified among 441 tested isolates.
CONCLUSIONS:

The analyses showed that extensive ingestion of DNA (100 μg plasmid) per day did not lead to increased proportions of kanamycin resistant bacteria, nor did it produce detectable transformants among the aerobic microbiota examined for 6 rats (detection limit < 1 transformant per 1,1 × 108 cultured bacteria). The key methodological challenges to HGT detection in animal feedings trials are identified and discussed. This study is consistent with other studies suggesting natural transformation is not detectable in the GIT of mammals.
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Metadaten
Author:Lise Nordgård, Lorenzo Brusetti, Noura Raddadi, Terje Traavik, Beate Averhoff, Kaare Magne Nielsen
URN:urn:nbn:de:hebis:30:3-236362
URL:http://www.biomedcentral.com/1756-0500/5/170
DOI:http://dx.doi.org/10.1186/1756-0500-5-170
ISSN:1756-0500
Pubmed Id:http://www.ncbi.nlm.nih.gov/pubmed?term= 22463741
Parent Title (English):BMC Research Notes
Publisher:BioMed Central
Place of publication:London
Document Type:Article
Language:English
Date of Publication (online):2012/06/04
Date of first Publication:2012/04/01
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2012/06/04
Volume:5
Issue:170
Pagenumber:11
HeBIS PPN:302905936
Institutes:Biowissenschaften
Dewey Decimal Classification:570 Biowissenschaften; Biologie
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 3.0

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