Why Cow Poo is dangerous: it contains a plethora of nanotech syringes for injecting poisons.

Pathogenic Escherichia coli bacteria of the O157 serological type (that caused a recent massive 20-state outbreak of death and disease in the US linked with faeces contamination in supermarket spinach) have highly developed interactions with the non bacterial hosts that they colonise during their dangerous and adventurous life-cycle. [Update March 2007. Reports in the US suggest a linkage to a farm in a transition to organic farming was linked to the incident.]

Survival of bacteria inside larger animal, plant, or protozoal hosts is often connected with bacterial ability to inject proteins into a host's cell (such as cells in the gut wall which the bacteria come in contact with). Through this injection capability bacteria can subvert the host's defence mechanisms in complex and highly evolved ways. The injected subversion proteins are called effector proteins. One well studied bacterial nano-machinery for delivering effector proteins is called the Type Three Secretion system (T3SS, called nanotech syringe in the tile of this post).

It turns out that E. coli O157 possess numerous nano-tech systems for delevery of effector proteins by this technique. A true plethora of poison laced syringes.

This plethora may suggest that E. coli is able to survive in many different species, eg worms, cows, plants, as well as humans.

This survival ability may well explain its ability to survive for extended periods in compost or soil, well away from the obvious food-feces-gut portion of its life cell.

Thus, buyer beware of compost for a long time after the poo hits the pile.


An extensive repertoire of type III secretion effectors in Escherichia coli O157 and the role of lambdoid phages in their dissemination.

Tobe T, Beatson SA, Taniguchi H, Abe H, Bailey CM, Fivian A, Younis R, Matthews S, Marches O, Frankel G, Hayashi T, Pallen MJ.

Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; University of Birmingham Medical School, Birmingham, B15 2TT,
United Kingdom; School of Molecular and Microbial Sciences, University of Queensland, Brisbane QLD 4072, Australia; Institute of Enzyme Research, University of Tokushima, 3-8-15 Kuramoto, Tokushima 770-8503, Japan; Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, United Kingdom.

Several pathogenic strains of Escherichia coli exploit type III secretion to inject "effector proteins" into human cells, which then subvert eukaryotic cell biology to the bacterium's advantage. We have exploited bioinformatics and experimental approaches to establish that the effector repertoire in the Sakai strain of enterohemorrhagic E. coli (EHEC) O157:H7 is much larger than previously thought. Homology searches led to the identification of more than 60 putative effector genes. Thirteen of these were judged to be likely pseudogenes, whereas 49 were judged to be potentially functional. In total, 39 proteins were confirmed experimentally as effectors: 31 through proteomics and 28 through translocation assays. At the protein level, the EHEC effector sequences fall into more than 20 families. The largest family, the NleG family, contains 14 members in the Sakai strain alone. EHEC also harbors functional homologs of effectors from plant pathogens (HopPtoH, HopW, AvrA) and from Shigella (OspD, OspE, OspG), and two additional members of the Map/IpgB family. Genes encoding proven or predicted effectors occur in >20 exchangeable effector loci scattered throughout the chromosome. Crucially, the majority of functional effector genes are encoded by nine exchangeable effector loci that lie within lambdoid prophages. Thus, type III secretion in E. coli is linked to a vast phage "metagenome," acting as a crucible for the evolution of pathogenicity.

Proc Natl Acad Sci U S A. 2006 Sep 21; [Epub ahead of print]
PMID: 16990433 [PubMed - as supplied by publisher]

Homologs of Effectors from Plant Pathogens.

Several EHEC candidate effectors show homology to T3SS effectors from plant pathogens, strengthening the idea that effectors generally target ancient and conserved aspects of eukaryotic cell biology (28)...

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