Genomic Analyses of the Novel Mycobacteriophage Settecandela
Dr. Aaron A. Best, Biology, Dr. Joseph Stukey
Eighteen new mycobacteriophages were isolated from soil samples collected around the state of Michigan and parts of the United States. All phages were capable of infecting Mycobacterium smegmatis and were isolated through either enrichment or direct plating at 32°C or 37°C. A variety of plaque morphologies were produced based on size, shape, and clarity; both lytic and temperate phages appear represented in this collection. The mycobacteriophage, Settecandela, was chosen as one of three phages for complete genome sequencing and comparative genomic analyses. The predominant plaque produced by Settecandela at 37°C was 1 mm in diameter, and took 48 hours to appear. The complete genome sequence for Settecandela revealed a relationship to the singleton, Phrappuccino, discovered by the Hope College phage class in 2016. The genome of Settecandela is 145.2 Kb, 67.4% GC, and contains 224 genes. The close relationship with Phrappuccino necessitates the formation of a new cluster of mycobacteriophages, Cluster AA. The two genomes are identical over much of their length, with the exception of an approximately 9000 bp region in Settecandela containing 25 genes. There is strong evidence at the morphological (Myoviridae) and genomic levels for a relationship to Cluster C phages. Despite this relationship, Cluster AA genomes do not carry any tRNA genes. A detailed analysis of the complete genome sequences and comparison with sequenced mycobacteriophages is the subject of the second semester of this yearlong course and is presented.
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