This article has an erratum: [erratum]
Environ. Biosafety Res.
Volume 2, Number 3, July-September 2003
|Page(s)||173 - 180|
|Published online||15 November 2003|
Worst-case scenarios for horizontal gene transfer from Lactococcus lactis carrying heterologous genes to Enterococcus faecalis in the digestive tract of gnotobiotic mice
Unité d'Ecologie et de Physiologie du Système digestif, INRA,
78352 Jouy-en-Josas, France
Corresponding author: email@example.com
Since genetically modified (GM) lactic acid bacteria (LAB) might be released in open environments for future nutritional and medical applications, the purpose of this study was to determine an upper limit for the horizontal gene transfer (HGT) in the digestive tract (DT) from Lactococcus lactis carrying heterologous genes (lux genes encoding a bacterial luciferase) to Enterococcus faecalis. Two enterococcal wide host-range conjugative model systems were used: (i) a system composed of a mobilizable plasmid containing the heterologous lux genes and a native conjugative helper plasmid; and (ii) a Tn916-lux transposon. Both systems were tested under the most transfer-prone conditions, i.e. germfree mice mono-associated with the recipient E. faecalis. No transfer was observed with the transposon system. Transfers of the mobilizable plasmid carrying heterologous genes were below 102 transconjugants per g of faeces for a single donor dose and reached between 103 and 104 transconjugants per g of faeces when continuous inoculation of the donor strain was used. Once established in mice, transconjugants persisted at low levels in the mouse DT.
Key words: Lactococcus lactis / Enterococcus faecalis / horizontal gene transfer / conjugative transposon / conjugative and mobilizable plasmids / digestive tract / luciferase / genetically modified bacteria / gnotobiotic mice
© ISBR, EDP Sciences, 2003