Isolation and characterization of the novel mycobacteriophage SLM01

Bacteriophage-based therapeutics represent a promising countermeasure against the accelerating threat of multidrug-resistant bacterial infections. In this study, a novel mycobacteriophage SLM01, was isolated from soil collected in Chengdu and subjected to comprehensive biological and genomic characterization. Analysis indicated that the SLM01 genome was 55 285 bp in length with a GC content of 61.05% and contained no ambiguous nucleotides, transfer-messenger RNA sequences, or antibiotic-resistant genes. Plaque assays on Mycobacterium smegmatis lawns revealed a distinctive double-ring morphology. Transmission electron microscopy demonstrated an icosahedral capsid and a long non-contractile tail, supporting classification within Siphoviridae of Caudoviricetes. In liquid culture experiments conducted at a multiplicity of infection (MOI) of 10, SLM01 reduced M. smegmatis growth and biofilm formation to the greatest extent. Stability assays showed that maximal phage viability was maintained at pH 6 and 4°C. One-step growth analysis indicated a latent period of 45 min followed by a logarithmic replication phase lasting 135 min. Phylogenetic analysis placed this novel mycobacteriophage SLM01 within subcluster F2, which expanding the genomic and phenotypic landscape of this mycobacteriophage lineage, and anticipated to expanding the resources for mycobacteriophage therapeutic development.