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Persistence of Verocytotoxigenic E. COLI 0157 in Aquatic Biofilms


Research objectives and content

VTEC verocytotoxigenic E coli), in particular E cold 0157:H7, have been recognised as a major food borne pathogens, and have caused several large outbreaks of haemorrhagic colitis in the USA, Japan and the UK. There is no specific treatment for the disease. Consequently, VTEC infection represents a significant and serious public health problem associated with food processing work surfaces and inefficiently disinfected potable water supplies. Direct observations have clearly shown that biofilm bacteria predominate, numerically and metabolically in different plumbing material or food processing work surfaces causing a multitude of problems because of the relative inefficiency of classical disinfection treatments.

The control and containment of E. I cold 0157 in safe maintenance of potable water supplied used for drinking, personal hygiene and I washing foodstuffs will be possible by studying the persistence of E. cold0157 in aquatic biofilms. The dispersion and survival of VTEC 0157 will be analysed by using a continuous-culture model of biofilm growing on a specific tile surface such as copper, galvanized iron, mild steel, stainless steel, bitumen-painted steel, or new materials such as polyethylene or PVC after classical disinfection treatments with chlorine and monochloramine at 5, 15 and 25rC. Detection of the pathogen, without disrupting the biofilm structure, will be performed by using a differential interference contrast (DIC) microscope after introducing a stable marker gene (Green Fluorescent Protein) into VTEC 0157. Metabolic state of cells embedded in the biofilm matrix will be analysed by using different fluorochromes such as cyanotetrazolium chloride (CTC) which allow characterisation of the respiratory activity of the cells. Such information is necessary to determine how attached microorganisms can survive in biofilms and be resistant.

Training content (objective, benefit and expected impact)

This two-year research project will provide a fundamental advance about the role of aquatic biofilms in the persistence and resistance of pathogen microorganisms to biocides and also practical advance for public health measures for eliminating and preventing dissemination of dangerous pathogens. The research will allow me to acquire new skills on advanced microscopy techniques, handling ACDP category microorganisms, utilising fermenter biotechnology and finally familiarizing myself on biofilms associated to plumbing materials. This new research will complete my experience about immobilized bacteria, bacterial biofilms and gene technology.

Links content industry / industrial relevance (22)


Microbiological Research Authority
Porton Down
SP4 0JG Salisbury - Wiltshire
United Kingdom