A new replication medium enables a rapid identification of φx-174 virus by synchronous fluorescence of Tryptophan.

Development of rapid methods for identification of bacteriophages based on their intrinsic fluorescence is challenging. Pure bacteriophages may be detected based on the strong fluorescence of the amino acid Tryptophan that exist in their proteins. Nevertheless, Tryptophan is a molecule that also exist in high quantities in the bacterial hosts and their cultivation media. In this work, we show that simple separation of the bacteriophage φx-174 from its E.coli host (grown on standard cultivation medium) by filtration is not sufficient for its identification based on the intrinsic fluorescence of its Tryptophan content. This is mostly because of the tryptophan residues that derive from the cultivation medium. We fabricate a new cultivation medium that does not have any significant fluorescence overlap with Tryptophan. By utilization of this new cultivation medium, we can identify φx174 based on the spectral fingerprint of its intrinsic Tryptophan content by synchronous fluorescence measurements.