Recombinant DNA transfer to Escherichia coli of human faecal origin in vitro and in digestive tract of gnotobiotic mice

Abstract

The role of helper elements in the mobilisation of pBR recombinant plasmids (tra−, mob−, oriT+ and tra−, mob−, oriT−) from genetically engineered Escherichia coli K12 strains to other K12‐strains and to wild‐type E. coli strains of human faecal origin was examined. Transfer experiments were done in the digestive tract of axenic (germ free) and gnotobiotic mice, associated with human faecal flora, HFF. The kinetics of implantation of donors, recipients and transconjugants were determined. Mobilisation of oriT+ pBR‐type plasmids, by trans‐complementation with the products of tra and mob genes was obtained with E. coli K12, in the digestive tract of axenic mice and the resulting transconjugants became established together with the recipient and donor strains. Such mobilisation was only observed sporadically with one E. coli of human origin in axenic mice, but did not occur in gnotobiotic HFF mice. The E. coli strains of human origin were able to promote transfer of an oriT− pBR‐type plasmid in vitro but not in axenic or gnotobiotic mice. Transconjugants of wild‐type strains obtained in in vitro mating experiments and inoculated into gnotobiotic HFF mice were eliminated as rapidly as the recombinant K12 strains. This work indicates that ≥ 50% of wild‐type E. coli strains were able to promote transfer of pBR oriT− plasmids in vitro.

Transfer of the shuttle vector pRRI207 between Escherichia coli and Bacteroides spp. in vitro and in vivo in the digestive tract of axenic mice and in gnotoxenic mice inoculated with a human microflora

“…Another hypothesis is that E. coli strains (donor and helper) are eliminated too rapidly in the HFF (faster than the transit marker); but despite this rapid transit, the transfer of the helper plasmid pRK2013 was observed. Other studies have demonstrated the same phenomenon [14,18].…”

“…E. coli HB101 carried a helper plasmid pRK2013 [17] that promotes mobilisation of pRRI207 [16]. Recipient strains were E. coli PG1 [18] of human origin, B. uniformis 1004 [16], B. vulgatus and Bacteroides spp. contained in HFF mice (this study).…”

Carica papaya seed macerate as inhibitor of conjugative R plasmid transfer from Salmonella typhimurium to Escherichia coli in vitro and in the digestive tract of gnotobiotic mice

“…When plasmid transfer occurs in the digestive tract, the resulting transconjugants are generally unable to become established in that indigenous bacterial community (Duval-Iflah et al, 1994). By contrast, the spreading of plasmids which encode resistance to clinically important antibiotics in pathogenic bacteria has been observed often during antimicrobial therapy, which is believed to modify the normal microbiota and to lower host resistance against colonization by pathogenic plasmid-bearing bacteria (Barza et al, 1987).…”

Genetically modified organisms: consequences for ruminant health and nutrition

“…Indeed, recent work has shown that conjugation in biofilms occurs far more frequently than previously thought [35]. In addition, numerous studies document the transfer of conjugative or mobilisable plasmids in the gut of rats or mice, both in gnotobiotic animals and in animals associated with human gut microflora [19,32].…”