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[Application of green fluorescence protein in the detection of E. coli O157:H7 in food].

OBJECTIVE
To introduce green fluorescence protein (GFP) into E. coli O157:H7 and improve the detection methods for this bacteria, and to study the kinetics of E. coli O157:H7.


METHODS
The plasmid pGFP was transferred into E. coli O157:H7. The characteristic of the new built O157:H7-pGFP strain was evaluated. Some food samples were inoculated with the recombinant strain under certain temperature to imitate different storage circumstances. The contaminated E. coli O157:H7 were counted after certain time.


RESULTS
The pGFP was stable in E. coli O157:H7. The E. coli O157:H7-pGFP inoculated in ground poultry meat and pasteurized milk were enriched to 35 000 approximately 200 000 times in 12 h under higher storage temperature (37 degrees C), whereas the quantity decreased slowly under lower temperature (4 degrees C).


CONCLUSION
The recombinant strain with the characters of ampicillin resistance and green fluorescence under UV 365 nm was a useful tool in detection methods improvement and bacteria survival studies.