Mycobacterium lutetiense sp. nov., Mycobacterium montmartrense sp. nov. and Mycobacterium arcueilense sp. nov., members of a novel group of non-pigmented rapidly growing mycobacteria recovered from a water distribution system

A polyphasic molecular approach to characterize a collection of grapevine endophytic bacteria with bioprotective potential

AIMS

The work presented here was conducted to characterize the biodiversity of a collection of bacterial isolates, mainly wood endophytes, as part of a research project focused on exploring their bioprotective potential for postharvest biological control of fruits.

METHODS AND RESULTS

This work was the basis for the development of a tailored method combining 16S rDNA sequencing and Rep-PCR to differentiate the isolates and identify them to genus level or below. More than one hundred isolates obtained from wood and roots of different grapevine genotypes were cultured on appropriate growth media and then subjected to the specified multistep molecular identification.

CONCLUSIONS

We have obtained good dereplication for grapevine-endophytic bacteria, together with reliable genetic identification. Both are essential prerequisites to properly characterize a biome bank and, at the same time, beneficial prerequisites to subsequently perform a correct bioprotection assessment.

Description of Mycolicibacterium arenosum sp. nov. Isolated from Coastal Sand on the Yellow Sea Coast

A Gram-staining-positive, aerobic, non-spore-forming bacterium was isolated from coastal sand samples from Incheon in the Republic of Korea and designated as strain CAU 1645T. The optimum conditions for growth were observed at 30 °C in growth media containing 1% (w/v) NaCl at pH 9.0. The predominant respiratory quinone was MK-9 and the major fatty acids were C16:0, C17:1 w7c, and summed feature 7. Similarly, the 16S rRNA gene sequence exhibited the highest similarity with Mycolicibacterium bacteremicum DSM 45578T and Mycolicibacterium neoaurum JCM 6365T, both of which exhibited similarity rates of 97.2%. The genomic DNA G+C content was 68.2%. The whole genome of strain CAU 1645T was obtained and annotated with annotation using RAST server. The pan-genome analysis was determined using Prokka, Roary, and Phandango. In the pan-genome analysis, the strain CAU 1645T shared 40 core genes with closely related Mycolicibacterium species, including the AcpM gene, the meromycolate extension acyl carrier protein involved in forming impermeable cell walls in mycobacteria. Therefore, our findings demonstrated that the isolate represents a novel species of the genus Mycolicibacterium, for which we propose the name Mycolicibacterium arenosum sp. nov. The type strain is CAU 1645T (= KCTC 49724T = MCCC 1K07087T).

Mycolicibacterium arseniciresistens sp. nov., isolated from lead-zinc mine tailing, and reclassification of two Mycobacterium species as Mycolicibacterium palauense comb. nov. and Mycolicibacterium grossiae comb. nov

A Gram-positive, acid-fast, aerobic, rapidly growing and non-motile strain was isolated from lead-zinc mine tailing sampled in Lanping, Yunnan province, Southwest China. 16S rRNA gene sequence analysis showed that the most closely related species of strain KC 300T was Mycolicibacterium litorale CGMCC 4.5724T (98.47 %). Additionally, phylogenomic and specific conserved signature indel analysis revealed that strain KC 300T should be a member of genus Mycolicibacterium, and Mycobacterium palauense CECT 8779T and Mycobacterium grossiae DSM 104744T should also members of genus Mycolicibacterium. The genome size of strain KC 300T was 6.2 Mb with an in silico DNA G+C content of 69.2 mol%. Chemotaxonomic characteristics of strain KC 300T were also consistent with the genus Mycolicibacterium. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values, as well as phenotypic, physiological and biochemical characteristics, support that strain KC 300T represents a new species within the genus Mycolicibacterium, for which the name Mycolicibacterium arseniciresistens sp. nov. is proposed, with the type strain KC 300T (=CGMCC 1.19494T=JCM 35915T). In addition, we reclassified Mycobacterium palauense and Mycobacterium grossiae as Mycolicibacterium palauense comb. nov. and Mycolicibacterium grossiae comb. nov., respectively.

A nontuberculous mycobacterium could solve the mystery of the lady from the Franciscan church in Basel, Switzerland

BACKGROUND

In 1975, the mummified body of a female has been found in the Franciscan church in Basel, Switzerland. Molecular and genealogic analyses unveiled her identity as Anna Catharina Bischoff (ACB), a member of the upper class of post-reformed Basel, who died at the age of 68 years, in 1787. The reason behind her death is still a mystery, especially that toxicological analyses revealed high levels of mercury, a common treatment against infections at that time, in different body organs. The computed tomography (CT) and histological analysis showed bone lesions in the femurs, the rib cage, and the skull, which refers to a potential syphilis case.

RESULTS

Although we could not detect any molecular signs of the syphilis-causing pathogen Treponema pallidum subsp. pallidum, we realized high prevalence of a nontuberculous mycobacterium (NTM) species in brain tissue sample. The genome analysis of this NTM displayed richness of virulence genes and toxins, and similarity to other infectious NTM, known to infect immunocompromised patients. In addition, it displayed potential resistance to mercury compounds, which might indicate a selective advantage against the applied treatment. This suggests that ACB might have suffered from an atypical mycobacteriosis during her life, which could explain the mummy's bone lesion and high mercury concentrations.

CONCLUSIONS

The study of this mummy exemplifies the importance of employing differential diagnostic approaches in paleopathological analysis, by combining classical anthropological, radiological, histological, and toxicological observations with molecular analysis. It represents a proof-of-concept for the discovery of not-yet-described ancient pathogens in well-preserved specimens, using de novo metagenomic assembly.

Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov., two new rapidly growing mycobacterial species

Four bacterial strains (LJ126^T/S18 and Z-34^T/S20) recovered from faecal samples of Tibetan antelopes on the Qinghai-Tibet Plateau of China were analysed using a polyphasic approach. All four isolates were aerobic, short rod-shaped, non-motile, Gram-stain-positive, acid-fast and fast-growing. Phylogenetic analyses based upon 16S rRNA and whole-genome sequences showed that the two pair of strains formed two distinct branches within the evolutionary radiation of the genus Mycolicibacterium. Strains LJ126^T/S18 and Z-34^T/S20 were most closely related to Mycolicibacterium austroafricanum CCUG 37667^T, Mycobacterium aurum NCTC 10437^T, Mycobacterium pyrenivorans DSM 44605^T, Mycobacterium monacense JCM 15658^T, Mycolicibacterium sarraceniae JCM 30395^T, Mycolicibacterium tokaiense JCM 6373^T and Mycobacterium murale JCM 13392^T, but readily distinguished from the known species by a combination of chemotaxonomic and phenotypic features and by low average nucleotide identity values (74.4-84.9 %). Consequently, the two strain pairs are considered to represent different novel species of Mycolicibacterium for which the names Mycolicibacterium baixiangningiae sp. nov. and Mycolicibacterium mengxianglii sp. nov. are proposed, with LJ126^T (=CGMCC 1.1992^T=KCTC 49535^T) and Z-34^T (=CGMCC 1.1993^T=DSM 106172^T) as the respective type strains.

Clinical Relevance and Environmental Prevalence of Mycobacterium fortuitum Group Members. Comment on Mugetti et al. Gene Sequencing and Phylogenetic Analysis: Powerful Tools for an Improved Diagnosis of Fish Mycobacteriosis Caused by Mycobacterium fortuitum Group Members. Microorganisms 2021, 9, 797

Mycobacterium fortuitum group (MFG) members are able to cause clinical mycobacteriosis in fish and other animals including humans. M. alvei, M. arceuilense, M. brisbanense, M. conceptionense, M. fortuitum, M. peregrinum, M. porcinum, M. senegalense, M. septicum, and M. setense were isolated from fish with mycobacteriosis. In other animals only three MFG species have been isolated: M. arceuilense from camels' milk, M. farcinogenes from cutaneous infections often described as "farcy", and M. fortuitum from different domestic and wild mammals' species. Out of 17, only 3 MFG species (M. arceuilense, M. lutetiense and M. montmartrense) have never been reported in humans. A total of eight MFG members (M. alvei, M. brisbanense, M. conceptionense, M. fortuitum subsp. acetamidolyticum, M. houstonense, M. peregrinum, M. porcinum, and M. septicum) have been isolated from both pulmonary and extrathoracic locations. In extrathoracic tissues five MFG species (M. boenickei, M. farcinogenes, M. neworleansense, M. senegalense, and M. setense) have been diagnosed and only one MFG member (M. fortuitum subsp. acetamidolyticum) has been isolated from pulmonary infection.

Gene Sequencing and Phylogenetic Analysis: Powerful Tools for an Improved Diagnosis of Fish Mycobacteriosis Caused by Mycobacterium fortuitum Group Members

The Mycobacterium fortuitum group (MFG) consists of about 15 species of fast-growing nontuberculous mycobacteria (NTM). These globally distributed microorganisms can cause diseases in humans and animals, especially fish. The increase in the number of species belonging to MFG and the diagnostic techniques panel do not allow to clarify their real clinical significance. In this study, biomolecular techniques were adopted for species determination of 130 isolates derived from fish initially identified through biochemical tests as NTM belonging to MFG. Specifically, gene sequencing and phylogenetic analysis were used based on a fragment of the gene encoding the 65 KDa heat shock protein (hsp65). The analyzes made it possible to confirm that all the isolates belong to MFG, allowing to identify the strains at species level. Phylogenetic analysis substantially confirmed what was obtained by gene sequencing, except for six strains; this is probably due to the sequences present in NCBI database. Although the methodology used cannot represent a univocal identification system, this study has allowed us to evaluate its effectiveness as regards the species of MFG. Future studies will be necessary to apply these methods with other gene fragments and to clarify the real pathogenic significance of the individual species of this group of microorganisms.

Phylogenomics and Comparative Genomic Studies Robustly Support Division of the Genus Mycobacterium into an Emended Genus Mycobacterium and Four Novel Genera

The genus Mycobacterium contains 188 species including several major human pathogens as well as numerous other environmental species. We report here comprehensive phylogenomics and comparative genomic analyses on 150 genomes of Mycobacterium species to understand their interrelationships. Phylogenetic trees were constructed for the 150 species based on 1941 core proteins for the genus Mycobacterium, 136 core proteins for the phylum Actinobacteria and 8 other conserved proteins. Additionally, the overall genome similarity amongst the Mycobacterium species was determined based on average amino acid identity of the conserved protein families. The results from these analyses consistently support the existence of five distinct monophyletic groups within the genus Mycobacterium at the highest level, which are designated as the "Tuberculosis-Simiae," "Terrae," "Triviale," "Fortuitum-Vaccae," and "Abscessus-Chelonae" clades. Some of these clades have also been observed in earlier phylogenetic studies. Of these clades, the "Abscessus-Chelonae" clade forms the deepest branching lineage and does not form a monophyletic grouping with the "Fortuitum-Vaccae" clade of fast-growing species. In parallel, our comparative analyses of proteins from mycobacterial genomes have identified 172 molecular signatures in the form of conserved signature indels and conserved signature proteins, which are uniquely shared by either all Mycobacterium species or by members of the five identified clades. The identified molecular signatures (or synapomorphies) provide strong independent evidence for the monophyly of the genus Mycobacterium and the five described clades and they provide reliable means for the demarcation of these clades and for their diagnostics. Based on the results of our comprehensive phylogenomic analyses and numerous identified molecular signatures, which consistently and strongly support the division of known mycobacterial species into the five described clades, we propose here division of the genus Mycobacterium into an emended genus Mycobacterium encompassing the "Tuberculosis-Simiae" clade, which includes all of the major human pathogens, and four novel genera viz. Mycolicibacterium gen. nov., Mycolicibacter gen. nov., Mycolicibacillus gen. nov. and Mycobacteroides gen. nov. corresponding to the "Fortuitum-Vaccae," "Terrae," "Triviale," and "Abscessus-Chelonae" clades, respectively. With the division of mycobacterial species into these five distinct groups, attention can now be focused on unique genetic and molecular characteristics that differentiate members of these groups.

Practice Guidelines for Clinical Microbiology Laboratories: Mycobacteria

Mycobacteria are the causative organisms for diseases such as tuberculosis (TB), leprosy, Buruli ulcer, and pulmonary nontuberculous mycobacterial disease, to name the most important ones. In 2015, globally, almost 10 million people developed TB, and almost half a million patients suffered from its multidrug-resistant form. In 2016, a total of 9,287 new TB cases were reported in the United States. In 2015, there were 174,608 new case of leprosy worldwide. India, Brazil, and Indonesia reported the most leprosy cases. In 2015, the World Health Organization reported 2,037 new cases of Buruli ulcer, with most cases being reported in Africa. Pulmonary nontuberculous mycobacterial disease is an emerging public health challenge. The U.S. National Institutes of Health reported an increase from 20 to 47 cases/100,000 persons (or 8.2% per year) of pulmonary nontuberculous mycobacterial disease among adults aged 65 years or older throughout the United States, with 181,037 national annual cases estimated in 2014. This review describes contemporary methods for the laboratory diagnosis of mycobacterial diseases. Furthermore, the review considers the ever-changing health care delivery system and stresses the laboratory's need to adjust and embrace molecular technologies to provide shorter turnaround times and a higher quality of care for the patients who we serve.

Mycobacterium aquaticum sp. nov., a rapidly growing species isolated from haemodialysis water

The characterization of five Iranian isolates, four from hospital haemodialysis water and one from the sputum of a patient, led to the detection of a novel mycobacterium species. The strains were characterized by mucoid colonies developing in 3-5 days at temperatures ranging from 25 to 37 °C. The biochemical test pattern was unremarkable while the HPLC profile of mycolic acids resembled that of Mycobacterium fortuitum. The sequences of three major housekeeping genes (16S rRNA, hsp65 and rpoB) were unique and differed from those of any other mycobacterium. Mycobacterium brisbanense, which is the species that shared the highest 16S rRNA gene sequence similarity (99.03 %), was distinct, as shown by the average nucleotide identity and by the genome to genome distance values (91.05 and 43.10 %, respectively). The strains are thus considered to represent a novel species of the genus Mycobacterium, for which the name Mycobacterium aquaticum sp. nov. is proposed. The type strain is RW6T (=DSM 104277T=CIP111198T).