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Microbiology Spectrum






e01158-21 (1-13)


Mycobacterium shottsii is a dysgonic, nonpigmented mycobacterium originally isolated from diseased striped bass (Morone saxatilis) in the Chesapeake Bay, USA. Genomic analysis reveals that M. shottsii is a Mycobacterium ulcerans/Mycobacterium marinum clade (MuMC) member, but unlike the superficially similar M. pseudoshottsii, also isolated from striped bass, it is not an M. ulcerans ecovar, instead belonging to a transitional group of strains basal to proposed “Aronson” and “M” lineages. Although phylogenetically distinct from the human pathogen M. ulcerans, the M. shottsii genome shows parallel but nonhomologous genomic degeneration, including massive accumulation of pseudogenes accompanied by proliferation of unique insertion sequences (ISMysh01, ISMysh03), large-scale deletions, and genomic reorganization relative to typical M. marinum strains. Coupled with its observed ecological characteristics and loss of chromogenicity, the genomic structure of M. shottsii is suggestive of evolution toward a state of obligate pathogenicity, as observed for other Mycobacterium spp., including M. ulcerans, M. tuberculosis, and M. leprae.


© 2022 Gauthier et al.

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license.

Data Availability

Article states: "The complete M. shottsii M175 genome sequence is available from NCBI GenBank, accession number CP014860. The complete M. marinum ATCC 927 genome was recently made available (41) (GenBank NZ_AP018496) and is syntenic and consistent with the ATCC 927 sequence produced in this work. Sequence reads for M. shottsii strains other than M175 are available from the NCBI Sequence Read Archive (PRJNA816683)."

Original Publication Citation

Gauthier, D. T., Doss, J. H., LaGatta, M., Gupta, T., Karls, R. K., & Quinn, F. D. (2022). Genomic degeneration and reduction in the fish pathogen Mycobacterium shottsii. Microbiology Spectrum, 10(3), 1-13, Article e01158-21.


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