Whole genome sequencing identifies an allele responsible for clear vs. turbid plaque morphology in a Mycobacteriophage.

Whole genome sequencing promises to revolutionize our ability to link genotypic and phenotypic variation in a wide range of model and non-model species. Here we describe the isolation and characterization of a novel mycobacteriophage named BGlluviae that grows on Mycobacterium smegmatis mc2155. BGlluviae normally produces turbid plaques but a spontaneous clear plaque was also recovered. The genomic DNA from pure populations of the BGlluviae phage and the clear plaque mutant were sequenced. A single substitution, at amino acid 54 (I to T), in the immunity repressor protein resulted in a clear plaque phenotype. This substitution is predicted to be located at the subunit interaction interface of the repressor protein, and thus prevents the establishment of lysogeny.