Three of a Kind: Genetically Similar Tsukamurella Phages TIN2, TIN3, and TIN4

Three Tsukamurella phages, TIN2, TIN3, and TIN4, were isolated from activated sludge treatment plants located in Victoria, Australia, using conventional enrichment techniques. Illumina and 454 whole-genome sequencing of these Siphoviridae viruses revealed that they had similar genome sequences, ranging in size between 76,268 bp and 76,964 bp. All three phages shared 74% nucleotide sequence identity to the previously described Gordonia phage GTE7. Genome sequencing suggested that phage TIN3 had suffered a mutation in one of its lysis genes compared to the sequence of phage TIN4, to which it is genetically very similar. Mass spectroscopy data showed the unusual presence of a virion structural gene in the DNA replication module of phage TIN4, disrupting the characteristic modular genome architecture of Siphoviridae phages. All three phages appeared highly virulent on strains of Tsukamurella inchonensis and Tsukamurella paurometabola.