Method for detecting bacteria with bacteriaphage

A method for determining the presence or absence of a bacterium in a sample, comprising the steps of:

• introducing into a bacteriophage a 1.1 kb HindIII polynucleotide fragment encoding a green-fluorescent protein (GFP) derived from Aequorea victorea to produce a transformed bacteriophage;
• contacting the sample with the transformed bacteriophage;
• allowing the transformed bacteriophage to bind to a bacterium which is present in the sample, the transformed bacteriophage being capable of specifically binding to the bacterium and growing in the bacterium;
• growing the transformed bacteriophage in the bacterium up to a level below where destruction of the bacterial cell occurs and expressing the green-fluorescent protein in the bacterial cell during which the cell number of the bacterium does not increase substantially;
• providing light of a first wavelength from outside the sample, whereby the actually-present bacterium emits light of a second wavelength;
• measuring the light of the second wavelength emitted by the light-emitting protein in the bacteria in the sample;
• and
• determining the presence or absence of the bacterium in the sample from the amount of light emitted compared to a sample containing none of the bacterium;
• wherein the bacterium is selected from the group consisting of Salmonella, Pseudomonas and E. coli;
• and wherein if the bacterium is suspected of being Salmonella, the bacteriophage is FELIX01;
• and wherein if the bacterium is suspected of being Pseudomonas, the bacteriophage is φ6 or PM2;
• and wherein if the bacterium is suspected of being E. coli, the bacteriophage is selected from the group consisting of T4, P2, T2, T7, λ, φX174 and MS2.