Mycobacterium cosmeticum sp. nov., a novel rapidly growing species isolated from a cosmetic infection and from a nail salon

Four isolates of a rapidly growingMycobacteriumspecies had a mycolic acid pattern similar to that ofMycobacterium smegmatis, as determined by HPLC analyses. Three of the isolates were from footbath drains and a sink at a nail salon located in Atlanta, GA, USA; the fourth was obtained from a granulomatous subdermal lesion of a female patient in Venezuela who was undergoing mesotherapy. By random amplified polymorphic DNA electrophoresis and PFGE of large restriction fragments, the three isolates from the nail salon were shown to be the same strain but different from the strain from the patient in Venezuela. Polymorphisms in regions of therpoB,hsp65and 16S rRNA genes that were shown to be useful for species identification matched for the two strains but were different from those of otherMycobacteriumspecies. The 16S rRNA gene sequence placed the strains in a taxonomic group along withMycobacterium frederiksbergense,Mycobacterium hodleri,Mycobacterium diernhoferiandMycobacterium neoaurum. The strains produced a pale-yellow pigment when grown in the dark at the optimal temperature of 35 °C. Biochemical testing showed that the strains were positive for iron uptake, nitrate reduction and utilization ofd-mannitol,d-xylose, iso-myo-inositol,l-arabinose, citrate andd-trehalose. The strains were negative ford-sorbitol utilization and production of niacin and 3-day arylsulfatase, although arylsulfatase activity was observed after 14 days. The isolates grew on MacConkey agar without crystal violet but not on media containing 5 % (w/v) NaCl or at 45 °C. They were susceptible to ciprofloxacin, amikacin, tobramycin, cefoxitin, clarithromycin, doxycycline, sulfamethoxazole and imipenem. The nameMycobacterium cosmeticumsp. nov. is proposed for this novel species; two strains, LTA-388T(=ATCC BAA-878T=CIP 108170T) (the type strain) and 2003-11-06 (=ATCC BAA-879=CIP 108169) have been designated, respectively, for the strains of the patient in Venezuela and from the nail salon in Atlanta, GA, USA.

[Molecular pathogenesis of mycobacterial diseases]

Mycobacterial diseases, including tuberculosis, leprosy, and disease due to nontuberculous mycobacteria, are the major cause of death from infectious diseases around the world. About one-third of the world population is latently infected with Mycobacterium tuberculosis. Over 8 million new cases and nearly 2 million deaths occur each year. Tuberculosis presents a significant health threat to the world. The pathogenicity of mycobacteria is related to their ability to escape killing by ingested macrophages, latent infection, and induce delayed type hypersensitivity. This has been attributed to several components of the mycobacterial cell wall, such as surface glycolipids, lipoarabinomannan, complement activation factor, heat-shock protein, and mycobacterial DNA binding protein. From the aspect of my research interests, I have focused on mycobacterial glycolipids and mycobacterial DNA binding protein in this article. Surface molecules of mycobacteria exert pleiotropic activities in both the microbe and host, and thus participate in the pathogenesis of mycobacterial diseases. The better understanding of mycobacterial pathogenicity may open the new avenue for the development of therapeutic and prophylactic interventions.

Proteomic Profiling of Intact Mycobacteria by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Current methods for the identification of mycobacteria in culture are time-consuming, requiring as long as 12 weeks for positive identification. One potential approach to rapid mycobacterial identification is to utilize proteomic profiling of cultures by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In this report, we have applied MALDI-TOF MS to proteomic profiling of cultured microorganisms representing six species of the genus Mycobacterium. We find that analysis of acetonitrile/trifluoroacetic acid cellular extracts produces data similar to that of the analysis of deposited whole cells, while minimizing human contact with the microorganisms and rendering them nonviable. A matrix composition of alpha-cyano-4-hydroxycinnamic acid with fructose yields highly reproducible MALDI-TOF spectra. Statistical analysis of MALDI-TOF MS data allows differentiation of each individual mycobacterial species on the basis of unique mass fingerprints. The methodology allows identification of a number of unique (potentially diagnostic) biomarkers as targets for protein identification by MS/MS experiments. In addition, we observe a number of signals common to all mycobacterial species studied by MALDI-TOF MS, which may be genus-specific biomarkers. The potentially genus-specific biomarkers occur at low mass (<2 kDa) and are likely to be lipids and cell wall components such as mycolic acids. This study demonstrates the potential for mass spectrometry-based identification/classification of mycobacteria.

Iron Chelation Properties of an Extracellular Siderophore Exochelin MS

The coordination chemistry of an extracellular siderophore produced by Mycobacterium smegmatis, exochelin MS (ExoMS), is reported along with its pK(a) values, Fe(III) and Fe(II) chelation constants, and aqueous solution speciation as determined by spectrophotometric and potentiometric titrations. Exochelin MS has three hydroxamic acid groups for Fe(III) chelation and has four additional acidic protons from a carboxylic acid group and three primary amine groups, on the backbone of the molecule. The pK(a) values for the three hydroxamic acid moieties, the carboxylic acid group and the alkylammonium groups on ExoMS, correspond well with the literature values for these moieties. Equilibrium constants for proton-dependent Fe(III)-ExoMS equilibria were determined using a model involving the sequential protonation of the Fe(III)-ExoMS complexes at the first and second coordination shells. The equilibrium constants (beta) for the overall formation of Fe(III)ExoMS(H(3))(2+) and Fe(II)ExoMS(H(3))(+) from Fe((aq))(3+) or Fe((aq))(2+) and the deprotonated hydroxamate coordinating group form of the siderophore, ExoMS(H(3))(-), are calculated as log beta(III) = 28.9 and log beta(II) = 10.1. A calculated pFe value of 25.0 is very similar to that of other linear trihydroxamic acid siderophores, and indicates that ExoMS is thermodynamically capable of removing Fe(III) from transferrin. The E(1/2) for the Fe(III)-ExoMS/Fe(II)-ExoMS couple was determined from quasi reversible cyclic voltammograms at pH = 6.5 and found to be -380 mV.

[Characterization of bacteria of the genera Mycobacterium, Rhodococcus and Nocardia isolated from environmental objects in the Republic of Daghestan]

The bacteriological study of specimens taken from environmental objects, biomaterials from animals and sputa from tuberculosis patients revealed the ubiquity of Mycobacterium, Nocardia and rhodococci obtained from different kinds of environment in the Republic of Daghestan. In the identification 83.6% out of the isolated atypical Mycobacterium cultures were classified with Ranion groups II and IV. Among Nocardia, the most widespread organisms were N. asteroides (62.7%) and among rhodococci, R. erithropolis (61.9%).

Electrokinetic transport of PAH-degrading bacteria in model aquifers and soil

An investigation of the mobility, viability, and activity of polycyclic aromatic hydrocarbon (PAH) degrading bacteria in an electric field is presented. Bench-scale model aquifers were used to test electrophoresis and electroosmosis as potential mechanisms for bacterial dispersion in contaminated sites. Glass beads, alluvial sand from Lake Geneva, and historically polluted clayey soil were used as packing materials. The green-fluorescent protein labeled PAH-degrading bacteria Sphingomonas sp. L138 and Mycobacterium frederiksbergense LB501TG were used as test organisms because of the known differing physicochemical surface and adhesion properties of the corresponding wild-type strains. No adverse effects of the electric current on bacterial viability and PAH-degradation were observed in the system chosen. Up to 90% of the weakly negatively charged and moderately adhesive cells of strain L138 were transported by electroosmosis, whereas 0-20% were transported by electrophoresis. By contrast, poor electrokinetic transport of strongly charged and highly adhesive cells of M. frederiksbergense LB501TG occurred in the different model aquifers. Treatment of bacteria with the nonionic surfactant Brij35 resulted in up to 80% enhanced electrokinetic dispersion of both strains. Our findings demonstrate that electroosmosis may be a valuable mechanism to transport bacteria in the subsurface with transport efficiencies heavily depending on the retention of the bacteria by the solid phase.

Gamma interferon production by bovine gamma delta T cells following stimulation with mycobacterial mycolylarabinogalactan peptidoglycan

A large percentage of lymphocytes in the blood of cattle express the gamma delta T-cell receptor, but specific functions for these cells have not yet been clearly defined. There is evidence, however, that human, murine, and bovine gamma delta T cells have a role in the immune response to mycobacteria. This study investigated the ability of bovine gamma delta T cells to expand and produce gamma interferon (IFN-gamma) in response to stimulation with mycobacterial products. Bovine gamma delta T cells, isolated from the peripheral blood of healthy cattle, expanded following in vitro stimulation with live mycobacteria, mycobacterial crude cell wall extract, and Mycobacterium bovis culture filtrate proteins. In addition, purified gamma delta T cells, cocultured with purified monocytes and interleukin-2, consistently produced significant amounts of IFN-gamma in response to mycobacterial cell wall. The IFN-gamma-inducing component of the cell wall was further identified as a proteolytically resistant, non-sodium dodecyl sulfate-soluble component of the mycolylarabinogalactan peptidoglycan.

Genome structure in the vole bacillus, Mycobacterium microti, a member of the Mycobacterium tuberculosis complex with a low virulence for humans

Mycobacterium microti, a member of the Mycobacterium tuberculosis complex, is phylogenetically closely related to M. tuberculosis, differing in a few biochemical properties. However, these species have different levels of virulence in different hosts; most notably M. microti shows lower virulence for humans than M. tuberculosis. This report presents genomic comparisons using DNA microarray analysis for an extensive study of the diversity of M. microti strains. Compared to M. tuberculosis H37Rv, 13 deletions were identified in 12 strains of M. microti, including the regions RD1 to RD10, which are also missing in Mycobacterium bovis BCG. In addition, four new deleted regions, named MiD1, RD1beta, MiD2 and MiD3, were identified. DNA sequencing was used to define the extent of most of the deletions in one strain. Although RD1 of M. bovis BCG and M. microti is thought to be crucial for attenuation, in this study, three of the four M. microti strains that were isolated from immunocompetent patients had the RD1 deletion. In fact, only the RD3 deletion was present in all of the strains examined, although deletions RD7, RD8 and MiD1 were found in almost all the M. microti strains. These deletions might therefore have some relation to the different host range of M. microti. It was also noticeable that of the 12 strains studied, only three were identical; these strains were all isolated from immunocompetent humans, suggesting that they could have arisen from a single source. Thus, this study shows that it is difficult to ascribe virulence to any particular pattern of deletion in M. microti.

Characterization of a novel group of mycobacteria and proposal of Mycobacterium sherrisii sp. nov

We describe here the characterization of five isolates of Mycobacterium simiae-like organisms representing a novel group based on whole-cell fatty acid analysis and genotypic evaluation. Two of the five isolates in this study, W55 and W58, were previously considered to belong to M. simiae serotype 2. Analysis of cellular fatty acids by gas-liquid chromatography indicated a close clustering of this group, which was well differentiated from the other M. simiae-like species. Molecular characterization was performed by nucleic acid sequencing of the small subunit rRNA gene and the gene encoding the 65-kDa heat shock protein and genomic DNA hybridization. Sequence analysis of the entire 16S rRNA gene showed a unique sequence most closely related to those of M. triplex and M. simiae. The hsp65 partial gene sequence was identical for the five isolates, with 97% identity to the M. simiae type strain. However, qualitative whole genomic DNA hybridization analysis confirmed that this group is genetically distinct from M. simiae and M. triplex. Antimicrobial susceptibilities for this group resemble those of M. simiae and M. lentiflavum. We conclude that this group represents a unique Mycobacterium species for which we propose the name Mycobacterium sherrisii sp. nov.

Characterization of multiple-substrate utilization by anthracene-degrading Mycobacterium frederiksbergense LB501T

Stable carbon isotope analysis of biomass and analyses of phospholipid fatty acids (PLFA), glycolipid fatty acids (GLFA), and mycolic acids were used to characterize mixed-substrate utilization by Mycobacterium frederiksbergense LB501T under various substrate regimens. The distinct (13)C contents of anthracene and glucose as representatives of typical hydrophobic pollutants and naturally occurring organic compounds, respectively, were monitored during formation into biomass and used to quantify the relative contributions of the two carbon sources to biomass formation. Moreover, the influence of mixed-substrate utilization on PLFA, GLFA, and mycolic acid profiles and cell surface hydrophobicity was investigated. Results revealed that M. frederiksbergense LB501T degrades anthracene and forms biomass from it even in the presence of more readily available dissolved glucose. The relative ratios of straight-chain saturated PLFA to the corresponding unsaturated PLFA and the total fraction of saturated cyclopropyl-branched PLFA of M. frederiksbergense LB501T depended on the carbon source and the various rates of addition of mixed substrates, whereas no such trend was observed with GLFA. Higher proportions of anthracene in the carbon source mixture led to higher cell surface hydrophobicities and more-hydrophobic mycolic acids, which in turn appeared to be valuable indicators for substrate utilization by M. frederiksbergense LB501T. The capability of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria to utilize readily available substrates besides the poorly available PAHs favors the buildup of PAH-degrading biomass. Feeding of supplementary carbon substrates may therefore promote bioremediation, provided that it sustains the pollutant-degrading population rather than other members of the microbial community.

Aggregation properties of mycolic acid molecules in monolayer films: a comparative study of compounds from various acid-fast bacterial species

Three kinds of mycolic acids (MAs) (alpha-, keto and methoxy-MAs) extracted from several species of mycobacteria were used to prepare monolayer films on water, and the surface pressure-area (pi-A) isotherms of the monolayers have been compared, so that the monolayer characteristics of the MAs as in cell walls would be revealed, since the monolayer molecular aggregation is related to drug permeability via the molecular packing. It was expected that the limiting molecular areas of the isotherms would be changed only a little, which reflects the minor difference in chemical structure and conformation of the mycobacteria. Nevertheless, the results are largely different from the expectation, and two greatly different patterns of the limiting molecular area have been observed. In a new model for elucidation of the results, two parts in an MA molecule are separately considered, and both contributions to the molecular unfolding by the monolayer compression have been suggested. This model is found to be useful to totally understand the isotherm behaviors of MAs. The relationship between monolayer properties and chemical structures for MAs has been summarized for the first time.

Sorting out self and microbial lipid antigens for CD1

CD1 proteins mediate T cell activation in response to self and foreign lipids, including lipid antigens from the intracellular pathogen Mycobacterium tuberculosis. During natural infections, myeloid cells migrate to sites of infection and use microbial pattern recognition receptors to internalize live bacteria and lipid antigens into the endosomal network. New studies show that certain CD1 proteins are particularly receptive to binding lipid antigens in the low pH environment of endosomes. Therefore, the endosomal network may represent a depot for concentrating and then selectively presenting exogenous foreign lipid antigens to T cells.

Mycobacterial porins--new channel proteins in unique outer membranes

Mycobacteria protect themselves with an outer lipid bilayer, which is the thickest biological membrane hitherto known and has an exceptionally low permeability rendering mycobacteria intrinsically resistant to many antibiotics. Pore proteins spanning the outer membrane mediate the diffusion of hydrophilic nutrients. Mycobacterium tuberculosis possesses at least two porins in addition to the low activity channel protein OmpATb. OmpATb is essential for adaptation of M. tuberculosis to low pH and survival in macrophages and mice. The channel activity of OmpATb is likely to play a major role in the defence of M. tuberculosis against acidification within the phagosome of macrophages. MspA is the main porin of Mycobacterium smegmatis. It forms a tetrameric complex with a single central pore of 10 nm length and a cone-like structure. This structure differs clearly from that of the trimeric porins of Gram-negative bacteria, which form one 4 nm long pore per monomer. The 45-fold lower number of porins compared to Gram-negative bacteria and the exceptional length of the pores are two major determinants of the low permeability of the outer membrane of M. smegmatis for hydrophilic solutes. The importance of the synergism between slow transport through the porins and drug efflux or inactivation for the development of drugs against M. tuberculosis is discussed.

Comparison of a multiplex-PCR assay with mycolic acids analysis and conventional methods for the identification of mycobacteria

A fast, sensitive and cost-effective multiplex-PCR assay for Mycobacterium tuberculosis complex (MTC) and Mycobacterium avium (M. avium) identification for routine diagnosis was evaluated. A total of 158 isolates of mycobacteria from 448 clinical specimens from patients with symptoms of mycobacterial disease were analyzed. By conventional biochemical methods 151 isolates were identified as M. tuberculosis, five as M. avium and two as Mycobacterium chelonae (M. chelonae). Mycolic acid patterns confirmed these results. Multiplex-PCR detected only IS6110 in isolates identified as MTC, and IS1245 was found only in the M. avium isolates. The method applied to isolates from two patients, identified by conventional methods and mycolic acid analysis, one as M. avium and other as M. chelonae, resulted positive for IS6110, suggesting co-infection with M. tuberculosis. These patients were successfully submitted to tuberculosis treatment. The multiplex-PCR method may offer expeditious identification of MTC and M. avium, which may minimize risks for active transmission of these organisms and provide useful treatment information.

Analogues of the mycobacterial arabinogalactan linkage disaccharide as cell wall biosynthesis inhibitors

The mycobacterial arabinogalactan linkage disaccharide [alpha-L-Rha-(1-->3)-alpha-D-GlcNAc] provides a basis for the design of new antitubercular drugs, since it supports a key skeletal structure in the bacterial cell wall. A series of analogues of the linker was synthesized by coupling appropriate thiorhamnosyl donors modified at their 4-positions, with an N-acetyl glucosamine acceptor. In a cell-free enzyme inhibition assay, three analogues inhibited the activity of the galactosyltransferase that adds a Galf residue to the linkage disaccharide. Although the compounds were modest inhibitors, these data confirm the viability of this approach to anti-mycobacterial agents. It is especially significant that the three effective compounds are modified at the site of the acceptor atom in the natural substrate.

Two polycyclic aromatic hydrocarbon o-quinone reductases from a pyrene-degrading Mycobacterium

Polycyclic aromatic hydrocarbon (PAH) o-quinone reductase (PQR) plays a crucial role in the detoxification of PAH o-quinones by reducing them to catechols. Two constitutive PQRs were found in cell extracts of a pyrene-degrading Mycobacterium sp. strain PYR100. The enzymes had an activity towards 9,10-phenanthrenequinone (PQ) and/or 4,5-pyrenequinone (PyQ), and the relative amounts varied with the pH of the culture media. PQR1, containing an FAD cofactor, was a monomer (20.1 kDa), and PQR2, with no flavin cofactor, was a homodimer (26.5 kDa subunits). There was no homology between the N-terminal sequences of PQR1 and PQR2. Dicumarol and quercetin inhibited PQR2 more strongly than PQR1. PQR1 had much lower specificity constants (k(cat)/K(m), 10(5)M(-1)s(-1)) for menadione (0.80) and PQ (5.19) than PQR2 (13.9 for menadione and 176 for PQ). Additionally, PQR2 exhibited a broad substrate specificity with high specificity constants for 1,4-naphthalenequinone, 1,2-naphthalenequinone, and PyQ.

Polymerization of mycobacterial arabinogalactan and ligation to peptidoglycan

The cell wall of Mycobacterium spp. consists predominately of arabinogalactan chains linked at the reducing ends to peptidoglycan via a P-GlcNAc-(alpha1-3)-Rha linkage unit (LU) and esterified to a variety of mycolic acids at the nonreducing ends. Several aspects of the biosynthesis of this complex have been defined, including the initial formation of the LU on a polyprenyl phosphate (Pol-P) molecule followed by the sequential addition of galactofuranosyl (Galf) units to generate Pol-P-P-LU-(Galf)1,2,3, etc. and Pol-P-P-LU-galactan, catalyzed by a bifunctional galactosyltransferase (Rv3808c) capable of adding alternating 5- and 6-linked Galf units. By applying cell-free extracts of Mycobacterium smegmatis, containing cell wall and membrane fragments, and differential labeling with UDP-[14C]Galp and recombinant UDP-Galp mutase as the source of [14C]Galf for galactan biosynthesis and 5-P-[14C]ribosyl-P-P as a donor of [14C]Araf for arabinan synthesis, we now demonstrate sequential synthesis of the simpler Pol-P-P-LU-(Galf)n glycolipid intermediates followed by the Pol-P-P-LU-arabinogalactan and, finally, ligation of the P-LU-arabinogalactan to peptidoglycan. This first time demonstration of in vitro ligation of newly synthesized P-LU-arabinogalactan to newly synthesized peptidoglycan is a necessary forerunner to defining the genetics and enzymology of cell wall polymer-peptidoglycan ligation in Mycobacterium spp. and examining this step as a target for new antibacterial drugs.

Iron chelation properties of an extracellular siderophore exochelin MN

The coordination chemistry of an extracellular siderophore produced by Mycobacterium neoaurum, exochelin MN (ExoMN), is reported along with its pK(a) values, Fe(III) and Fe(II) chelation constants, and aqueous solution speciation as determined by spectrophotometric and potentiometric titration techniques. Exochelin MN is of particular interest as it can efficiently transport iron into pathogenic M. leprae, which is responsible for leprosy, in addition to its own parent cells. The Fe(III) coordination properties of ExoMN are important with respect to understanding the Fe(III) acquisition and uptake mechanism in pathogenic M. leprae, as the siderophores from this organism are very difficult to isolate. Exochelin MN has two hydroxamic acid groups and an unusual threo-beta-hydroxy-l-histidine available for Fe(III) chelation. The presence of threo-beta-hydroxy-l-histidine gives rise to a unique mode of Fe(III) coordination. The pK(a) values for the two hydroxamic acid moieties, the histidine imidazole ring and the alkylammonium groups on ExoMN, correspond well with the literature values for these moieties. Proton-dependent Fe(III)- and Fe(II)-ExoMN equilibrium constants were determined using a model involving sequential protonation of the Fe(III)- and Fe(II)-ExoMN complexes. These data were used to develop a model whereby deprotonation reactions on the surface of the complex in the second coordination shell result in first coordination shell isomerization. The overall formation constants were calculated: log beta(110) = 39.12 for Fe(III)-ExoMN and 16.7 for Fe(II)-ExoMN. The calculated pFe value of 31.1 is one of the highest among all siderophores and their synthetic analogues and indicates that ExoMN is thermodynamically capable of removing Fe(III) from transferrin. The E(1/2) for the Fe(III)ExoMN/Fe(II)ExoMN(-) couple was determined to be -595 mV from quasi-reversible cyclic voltammograms at pH = 10.8, and the pH-dependent E(1/2) profile was used to determine the Fe(II)-ExoMN protonation constants.

Identification of a novel mannose-capped lipoarabinomannan from Amycolatopsis sulphurea

The genus Amycolatopsis is a member of the phylogenetic group nocardioform actinomycetes, which also includes the genus Mycobacterium. Members of this group have a characteristic cell envelope structure, dominated by various complex lipids and polysaccharides. Amongst these, lipoglycans are of particular interest since mycobacterial lipoarabinomannans are important immunomodulatory molecules. In this study we report the isolation and structural characterization of Amycolatopsis sulphurea lipoarabinomannan, designated AsuLAM. SDS/PAGE analysis revealed that AsuLAM was of an intermediate size between Mycobacterium tuberculosis lipoarabinomannan and lipomannan, confirmed by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry that predicted an average molecular mass of 10 kDa. Using a range of chemical degradations, NMR experiments and capillary electrophoresis analysis, AsuLAM was revealed as an original structure. The mannosyl-phosphatidyl- myo -inositol anchor exhibits a single acyl-form, characterized by a diacylated glycerol moiety, and contains, as one of the main fatty acids, 14-methyl-pentadecanoate, a characteristic fatty acid of the Amycolatopsis genus. AsuLAM also contains a short mannan domain; and is dominated by a multi-branched arabinan domain, composed of an (alpha1-->5)-Ara f (arabinofuranose) chain substituted, predominately at the O -2 position, by a single beta-Ara f. The arabinan domain is further elaborated by manno-oligosaccharide caps, with around one per molecule. This is the first description of manno-oligosaccharide caps found in a non-mycobacterial LAM. AsuLAM was unable to induce the production of the pro-inflammatory cytokine tumour necrosis factor alpha when tested with human or murine macrophage cell lines, reinforcing the paradigm that mannose-capped LAM are poor inducers of pro-inflammatory cytokines.

Selective cleavage of 10-methyl benzo[b]naphtho[2,1-d]thiophene by recombinant Mycobacterium sp. strain

Recombinant Mycobacterium sp. strain MR65 carrying dszABCD genes was used for desulfurization of 10-methylbenzo[b]naphtho[2,1-d]thiophene (10-methyl BNT) in the hexadecane phase. The specific activity was 25% of that of dibenzothiophene (DBT). One of two major metabolites of 10-methyl BNT produced by strain MR65 was identified as 1-methoxy-2-(3-methylphenyl)naphthalene by 1H and 13C NMR. The other major metabolite and two minor metabolites were determined as 1-hydroxy-2-(3-methylphenyl)naphthalene, 2-(2-methoxy-3-methylphenyl)naphthalene and 2-(2-hydroxy-3-methylphenyl)naphthalene, respectively, by HPLC and GC-MS. The production ratio of the two desulfurization metabolite isomers was 0.99:0.01, calculated on the basis of peak GC areas. These results indicated that the C-S bond adjacent to the naphthalene skeleton was selectively cleaved to form the two major compounds.

Impact of genotypic studies on mycobacterial taxonomy: the new mycobacteria of the 1990s

The advancement of genetic techniques has greatly boosted taxonomic studies in recent years. Within the genus Mycobacterium, 42 new species have been detected since 1990, most of which were grown from clinical samples. Along with species for which relatively large numbers of strains have been reported, some of the new species of mycobacteria have been detected rarely or even only once. From the phenotypic point of view, among the new taxa, chromogens exceed nonchromogens while the numbers of slowly and rapidly growing species are equivalent. Whereas conventional identification tests were usually inconclusive, an important role was played by lipid analyses and in particular by high-performance liquid chromatography. Genotypic investigations based on sequencing of 16S rRNA gene have certainly made the most important contribution. The investigation of genetic relatedness led to the redistribution of the species previously included in the classically known categories of slow and rapid growers into new groupings. Within slow growers, the intermediate branch related to Mycobacterium simiae and the cluster of organisms related to Mycobacterium terrae have been differentiated; among rapid growers, the group of thermotolerant mycobacteria has emerged. The majority of species are resistant to isoniazid and, to a lesser extent, to rifampin. Many of the new species of mycobacteria are potentially pathogenic, and there are numerous reports of their involvement in diseases. Apart from disseminated and localized diseases in immunocompromised patients, the most frequent infections in immunocompetent people involve the lungs, skin, and, in children, cervical lymph nodes. The awareness of such new mycobacteria, far from being a merely speculative exercise, is therefore important for clinicians and microbiologists.

Gas-chromatographic lipid profiles in identification of currently known slowly growing environmental mycobacteria

Cellular fatty acid analysis by GLC is widely used in the species identification of mycobacteria. Combining mycolic acid cleavage products with shorter cellular fatty acids increases the informative value of the analysis. A key has been created to aid in the identification of all currently known slowly growing environmental species. In this scheme, the species are classified into six categories, each characterized by a combination of fatty markers shared by those species. Within each category, individual species may be distinguished by the presence or absence of specific marker substances, such as methyl-branched fatty acids or secondary alcohols. This study also describes earlier unpublished GLC profiles of 14 rare, slowly growing, environmental mycobacteria, Mycobacterium asiaticum, Mycobacterium botniense, Mycobacterium branderi, Mycobacterium conspicuum, Mycobacterium cookii, Mycobacterium doricum, Mycobacterium heckeshornense, Mycobacterium heidelbergense, Mycobacterium hiberniae, Mycobacterium kubicae, Mycobacterium lentiflavum, Mycobacterium scrofulaceum, Mycobacterium triplex and Mycobacterium tusciae. Though no single identification technique alone, even sequencing of an entire single gene such as 16S rRNA, can identify all mycobacterial species accurately, GLC has proven to be both reliable and reproducible in the identification of slowly growing mycobacteria. In cases of earlier unknown species, it generates useful information that allows their further classification and may lead to the description of novel species.

Identification of three strains of Mycobacterium species isolated from clinical samples using fatty acid methyl ester profiling

The cellular fatty acid profiles of 67 strains belonging to three different species of the genus Mycobacterium were determined by gas chromatography of the fatty acid methyl esters, using the MIDI Sherlock Microbial Identification System (MIS). The species M. tuberculosis, M. xenopi and M. avium complex were clearly distinguishable and could be identified based on the presence and concentrations of 12 fatty acids: 14:0, 15:0, 16:1 omega 7c, 16:1 omega 6c, 16:0, 17:0, 18:2 omega 6.9c, 18:1 omega 9c, 18:0, 10Me-18:0 tuberculostearic acid, alcohol and cyclopropane. Fatty acid analysis showed that there is great homogeneity within and heterogeneity between Mycobacterium species. Thus the MIS is an accurate, efficient and relatively rapid method for the identification of mycobacteria.