Effects of yoghurt intake on plasmid transfer and colonisation with transconjugants in the digestive tract of mice associated with human faecal flora

Abstract

This study deals with the effects of yoghurt intake on wild-type and recombinant plasmid transfer from an exogenous Escherichia coli K12-derivative donor strain to an endogenous recipient strain in the digestive tract of mice associated with human faecal flora. We showed that the self-transmissible plasmid R388 was efficiently transferred to recipient strain PG1 in mice associated with human faecal flora (HFF-PG1) and that the resulting transconjugants (PG1-R388) became established at a high and maximal population level without any selective pressure. Using HFF-PG1 mice made it possible to determine whether yoghurt consumption decreases R388 transfer efficiency and the ability of transconjugant PG1-R388 to successfully colonise the digestive tract. Results indicated that yoghurt consumption had two effects: it reduced the efficacy of plasmid transfer 10-fold and decreased the transconjugant PG1-R388 population density 100-fold, compared to the control group. We also describe another HFF mouse model in which recipient PG1 was replaced by EM0 with which no plasmid transfer was observed. This model made it possible to demonstrate the potential promoting effect of yoghurt intake on transconjugant formation and establishment. Our results indicated no yoghurt effect; no transconjugants appeared in the digestive tract of HFF-EM0 mice fed on yoghurt or on standard food. In both mouse models, HFF-PG1 and HFF-EM0, yoghurt intake did not promote the mobilisation of either the non-self-transmissible plasmid pUB2380 or the recombinant plasmid pCE325.

Nutrition Related Stress Factors Reduce the Transfer of Extended-Spectrum Beta-Lactamase Resistance Genes between an Escherichia coli Donor and a Salmonella Typhimurium Recipient In Vitro

“…Bacterial metabolites may also have an impact on bacterial physiology in vivo. For instance, a reduction of conjugation frequency was previously reported in the presence of lactic acid producing bacteria, such as Streptococcus thermophilus , Lactobacillus fermentum , Lactobacillus plantarum , and L actobacillus bulgar icus [19,60,61,62,63]. This effect was assumed to be due to their lactate production among other factors.…”

“…There are different ways to calculate CF using the donor or recipient count as reference:Conjugation frequency based on donor count false(CFfalse(normalDfalse)false) = Transconjugants/mLDonors/mL, [15,16,17]. Conjugation frequency based on to recipient count false(CFfalse(normalRfalse)false) = Transconjugants/mLRecipients/mL, [18,19]. It must be considered for studies on stress response that these methods of calculation neglect the impact of the used stressor on the growth of the different participants.…”

Evolution of commensal bacteria in the intestinal tract of mice

“…Conjugation within the microbiota can be common and occur in a short timeframe. A study using GF mice, colonized with human feces, found that a natural plasmid could be transferred between E. coli strains at a frequency of 10 -5 after 6 hours of colonization [62]. In another study, the in vivo conjugation frequency of transposon Tn1545 from Enterococcus faecalis to Listeria monocytogenes in the gut of gnotobiotic mice was 1.1 x 10 -8 after 35 days [50].…”

Evolutionary Mechanisms Shaping the Maintenance of Antibiotic Resistance

“…Conjugation and transduction frequencies can be much higher in vivo than in vitro [29,[119][120][121][122]. For example, in the context of the gut microbiota it was found that inflammation could greatly increase the rates of plasmid and bacteriophage transfer between Salmonella strains.…”