Isolation and complete genome sequence of a novel Mycobacterium phage MS619.

Mycobacterium, an opportunistic pathogen, is highly prone to causing infections in humans, and its resistance to antibiotics poses a significant challenge. Phage therapy has emerged as a highly promising alternative treatment. In this study, a bacteriophage infecting Mycobacterium smegmatis was isolated from soil, named MS619, and classified within the class Caudoviricetes. Phages have an icosahedral head (60 ± 2 nm in diameter) and a long, non-contractile tail with a size of 125 ± 2 nm. The genome of MS619 was found to be a double-stranded DNA composed of 48,955 bp, containing 76 open reading frames (ORFs), related to phage packaging, structure, lysin, regulation, and replication. The BLASTN results indicated that MS619 exhibits a high-sequence identity (93%) with Mycobacterium phage Georgie2, a known bacteriophage recorded in the NCBI GenBank database. A typical holin-lysin system was identified in the MS619 genome. The topology of holin was predicted to contain two transmembrane domains, which significantly contribute to antimicrobial activity. No antibiotic resistance- or virulence factor-related genes were detected in the phage. Moreover, the bacteriophage demonstrates biofilm growth inhibition capability. This study led to the isolation of MS619, a bacteriophage exhibiting potential antibacterial efficacy against Mycobacterium infections.