Extensive genomic diversity among Mycobacterium marinum strains revealed by whole genome sequencing

Abstract

Mycobacterium marinum is the causative agent for the tuberculosis-like disease mycobacteriosis in fish and skin lesions in humans. Ubiquitous in its geographical distribution, M. marinum is known to occupy diverse fish as hosts. However, information about its genomic diversity is limited. Here, we provide the genome sequences for 15 M. marinum strains isolated from infected humans and fish. Comparative genomic analysis of these and four available genomes of the M. marinum strains M, E11, MB2 and Europe reveal high genomic diversity among the strains, leading to the conclusion that M. marinum should be divided into two different clusters, the “M”- and the “Aronson”-type. We suggest that these two clusters should be considered to represent two M. marinum subspecies. Our data also show that the M. marinum pan-genome for both groups is open and expanding and we provide data showing high number of mutational hotspots in M. marinum relative to other mycobacteria such as Mycobacterium tuberculosis. This high genomic diversity might be related to the ability of M. marinum to occupy different ecological niches.

Investigating hospital Mycobacterium chelonae infection using whole genome sequencing and hybrid assembly

“…This is similar to Mycobacterium marinum, a species that targets fish, and Mycobacterium avium, a species that can cause respiratory illness in humans, which showed up to 89,000 SNVs (24,054.1 SNVs per Mbp) and 26,871 SNVs (6249.1 SNVs per Mbp), respectively. Both show more variation than Mycobacterium tuberculosis, which showed a maximum 1800 SNVs between strains [31][32][33].…”

Insight into the biology of Mycobacterium mucogenicum and Mycobacterium neoaurum clade members

“…The difference is mainly related to that Mtb H73Rv and Mmar T both have larger numbers of genes in the categories “Cell surface components” and “Secretion system” while the number of mce genes is lower. Of the five type VII secretion systems (ESX 1-5) identified in Mtb H37Rv and Mmar (which also has ESX-6 but no ESX-2), ESX-1, -3 and -5 have been reported to affect virulence 20,46,48–52 . The Mmuc - and Mneo -clade members lack ESX-5 genes but carry ESX-1 and ESX-3.…”

“…Isolates of various mycobacteria such as Mycobacterium abscessus , Mycobacterium salmoniphilum and Mmar can form smooth and rough colony morphotypes (CM) when grown on solid media 24,52,58 . We also note that Mycobacterium canettii with its unusual CM is referred to as the “smooth tubercle bacilli” 59,60 .…”

“…Analysis of in particular M. abscessus , Msmeg and Mycobacterium avium strains reveals that the smooth and rough CM are related to genes involved in generating glycopeptidolipids (GPL locus), which are exposed on the cell surface. Mutations or deletion of genes within the GPL locus can result in transition from a smooth (S) to a rough (R) CM, where mycobacteria with rough CM appear to be more virulent 24,52 . Mmuc T is highly mucoid when grown on solid media 3,5 and surveying the GPL locus shows that several of the genes are absent in these members of the Mmuc - and Mneo -clades.…”

Mycobacterium marinum infection simulating chromomycosis: a case report

“…The infection in humans, due to contact with contaminated water or fish is comparatively rare with an incidence of 0.04 to 0.27 cases per 100,000 inhabitants per year 4 . First described as a "swimming-pool granuloma", M. marinum skin infection is nowadays acquired in the maintenance of aquariums and, therefore, is called "fish tank granuloma" or aquarium granuloma 5 .…”