title: Worst-case scenarios for horizontal gene transfer from Lactococcus lactis carrying heterologous genes to Enterococcus faecalis in the digestive tract of gnotobiotic mice.
abstract: 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 10(2) transconjugants per g of faeces for a single donor dose and reached between 10(3) and 10(4) 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.
authors.affiliation: Unité d'Ecologie et de Physiologie du Système digestif, INRA, 78352 Jouy-en-Josas, France.
authors.forename: Carl-Alfred
authors.initials: CA
authors.lastname: Alpert
authors.forename: Denis D G
authors.initials: DD
authors.lastname: Mater
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Muller
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Ouriet
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Duval-Iflah
authors.forename: Gérard
authors.initials: G
authors.lastname: Corthier
mesh_terms: D000818:Animals; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D013293:Enterococcus faecalis / Q000235:genetics* / Q000254:growth & development; D041981:Gastrointestinal Tract / Q000382:microbiology*; D022761:Gene Transfer, Horizontal; D005856:Germ-Free Life; D013294:Lactococcus lactis / Q000235:genetics*; D051379:Mice; D008809:Mice, Inbred C3H; D010957:Plasmids; D014169:Transformation, Bacterial
chemical_list: D004251:DNA Transposable Elements