Transfer of plasmids between strains of <i>Escherichia coli</i> under rumen conditions

Scott, Karen P.; Flint, Harry J.

doi:10.1111/j.1365-2672.1995.tb02841.x

Cited by 37 publications

(31 citation statements)

References 18 publications

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“…Relatively early in the understanding of rumen microbiology, Wolin (1969) reported that VFA were more inhibitory to the growth of E. coli than of other rumen bacteria. Since then, the occurrence of relatively low numbers of E. coli in the ruminant gut has been ascribed to the inhibitory effects of VFA, and more recent work has supported this view (Rasmussen et al 1993;Scott and Flint 1995). It is often difficult to unravel some of the reported effects of the diet and animal husbandry practice from effects of VFA.…”

Section: Effects Of Weak Acidsmentioning

confidence: 99%

“…However, E. coli K-12 is not representative of either commensal or E. coli0157 strains, as strains of E. coli K-12 lack some of the long-chain lipopolysaccharides (LPS) which confer protection on strains of E. coli, including 0157. For example, Scott and Flint (1995) found that some ovine rumen commensal strains of E. coli were able to grow at normal rates in anaerobic media at pH 7 in the presence of 50 mmol 1-1 VFA, whereas growth of a laboratory K-12 strain was completely inhibited under these conditions. A VFA concentration of 100mmol 1-1 was inhibitory to growth of the rumen strains, particularly at pH 6, and tolerance of VFA was greatest under aerobic growth conditions.…”

Section: Effects Of Weak Acidsmentioning

confidence: 99%

“…Further, the growth rates of a strain of E. coli 0157 under a range of acid conditions were comparable with those of a rumen strain (Duncan et al 1999a). The relative tolerance of VFA did not appear to be unique to rumen-derived strains as it was a feature shared by four fresh commensal isolates of E. coli from porcine faeces (Scott and Flint 1995). Booth et al (1999) compared the acid tolerance of E. coli 0157 with that of other strains of E. coli.…”

Section: Effects Of Weak Acidsmentioning

confidence: 99%

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The potential for the control ofEscherichia coliO157 in farm animals

Duncan¹,

Booth

Flint³

et al. 2000

Journal of Applied Microbiology

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SUMMARY The presence of Escherichia coli O157 in the faeces of farm animals appears to provide a primary route for human infection, either through physical contact or by contamination of the food chain. Controlling the survival and proliferation of this pathogen in the ruminant gut could offer a measure of protection in the short term, and ultimately complement alternative biotechnological based solutions. Normally, E. coli is greatly outnumbered in the ruminant gut by anaerobic bacteria, producers of weak acids inhibitory to the growth of this species. Withdrawal of feed prior to animal slaughter reduces the concentration of these acids in the gut and may be accompanied by the proliferation of E. coli. There are conflicting reports concerning the effects of changes in the ruminant diet upon faecal shedding of E. coli O157. It is contended that it is important to identify animal husbandry methods or feed additives that may be accompanied by an increased risk of proliferation of this pathogen. Greater understanding of the mechanisms involved in bacterial survival in the presence of weak acids, in the interactions between E. coli and other gut bacteria, and of the effects of some antibacterial plant secondary plant compounds on E. coli, could lead to the development of novel control methods.

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Section: Effects Of Weak Acidsmentioning

confidence: 99%

Section: Effects Of Weak Acidsmentioning

confidence: 99%

Section: Effects Of Weak Acidsmentioning

confidence: 99%

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The potential for the control ofEscherichia coliO157 in farm animals

Duncan¹,

Booth

Flint³

et al. 2000

Journal of Applied Microbiology

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“…Nevertheless Scott and Flint [70] demonstrated conjugative transfer of an antibiotic resistance plasmid between two strains of E. coli under anaerobic conditions in the presence of whole rumen contents. Transfer occurred at substantially lower rates compared with clue to the tetW origin may lie in its higher DNA % G +C content compared with other ribosome protection genes, but it is currently unclear whether tetW is a recent acquisition from soil microorganisms, or a long standing resident within the gut microbial community.…”

Section: Conjugal Transfermentioning

confidence: 99%

Genetically modified organisms: consequences for ruminant health and nutrition

Forano

Flint²

2000

Ann. Zootech.

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-Many of the plants eaten by farmed ruminants are capable of being genetically modified, and may in the future be modified for nutritional, agronomic or industrial purposes. Techniques are also becoming available for genetic modification of silage and ruminal bacteria. Those working in agricultural biotechnology have a clear responsibility to detect and avoid any unintended or undesirable consequences of such modifications, whether direct or indirect, upon the animal, the consumer and the environment. One of the most general concerns that has been expressed is the possibility for onward transfer of modified gene sequences to gut microorganisms or host cells. Rare acquisition of diet-derived DNA fragments cannot be ruled out, but if this occurs, it must have also occurred throughout mammalian history. The possible impact of genes not normally present in ruminant diets must, however, be considered. Discussion of the use of antibiotic resistance markers in transgene constructs must take into account the wider debate on the likely impact of antibiotic use in animal agriculture on the spread of antibiotic resistant bacteria. There is increasing evidence that overuse of antibiotics has lead to extensive transfer of antibiotic resistance genes between bacteria from the human and animal gut. In general this is likely to have a far greater impact than any rare transfer events involving resistance genes passing from transgenic plants to microbes. Our rapidly improving ability to use sophisticated molecular approaches to predict and track the consequences of genetic modification will help to ensure safe application of GM technology in agriculture in the future. GMO / rumen / ruminant nutrition / gene transferRésumé -Organismes génétiquement modifiés : conséquences pour la santé et la nutrition des ruminants. La plupart des plantes actuellement consommées par les ruminants d'élevage peut être -ou est déjà -manipulée génétiquement, et il est probable que ces plantes seront encore modifiées dans le futur pour améliorer leurs propriétés nutritionnelles, agronomiques ou technologiques. Par ailleurs, il est maintenant techniquement possible de modifier génétiquement les ferments d'ensilage ou les bactéries du rumen. Les chercheurs impliqués dans ces biotechnologies doivent donc être capables Ann. Zootech. 49 (2000) 255-271 255

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“…fibrisolvens [25] and Selenomonas ruminantium [26] have plasmids been found that are large enough to carry significant amounts of information beyond the genes necessary for their own replication and maintenance. Plasmid transfer in the presence of a complete rumen flora has been demonstrated only for rumen E. coli [27]. Recent work has demonstrated natural, high frequency transfer of a tetracycline resistance determinant between strains of Bu.…”

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confidence: 99%