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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two closely related species of mycobacteria, Mycobacterium vaccae and M. neoaurum, were grown under conditions of iron-deficiency (0.02-0.05 microgram Fe ml-1) and iron-sufficiency (2-4 micrograms Fe ml-1) in a simple glycerol/asparagine medium. The strain of M. vaccae used was a nonmycobactin producer whereas M. neoaurum synthesized between 6-8% of its cell biomass as the lipid-soluble siderophore when grown under iron-limitation. The role of mycobactin for iron-acquisition was examined using both pure and mixed cultures, with cell viability determined following growth at various iron concentrations. M. neoaurum, the mycobactin producer, outgrew M. vaccae when iron was readily available. When grown under conditions where iron was limiting, M. neoaurum showed a decline in viable cell number compared with its competitor, highlighting its increased requirement for the metal. Some recovery was observed following mycobactin biosynthesis, this being greatly enhanced by the addition of an iron supplement to the growing cells. Mycobactin biosynthesis allowed M. neoaurum to rapidly acquire any additional iron presented to the bacteria when growing under iron-limitation. However, M. vaccae did not synthesize the lipid-soluble siderophore with its iron-requirement satisfied by production of extracellular exochelin.
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PMID:Mycobactin and the competition for iron between Mycobacterium neoaurum and M. vaccae. 373 52

Superoxide dismutase (EC 1.15.1.1) (SOD) activity has been detected in crude cell extracts of representative strains of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) group. Polyacrylamide gel electrophoresis demonstrated a single SOD activity band for each of the MAIS strains, though there were differences in mobility. All M. avium and M. intracellulare and two of five M. scrofulaceum strains demonstrated a single activity band of identical mobility (Rf = 0.83), while the SOD activity band for the three remaining M. scrofulaceum strains migrated farther (Rf = 0.85). The differences in mobility correlated with differences in sensitivity to NaN3 and H2O2. The SOD activities of the majority of the MAIS strains which displayed the slower-migrating activity band were inhibited 22 to 81% after 15 min of exposure to 5 mM H2O2, suggesting that both iron and manganese may be present in a single enzyme. The SOD activities of the three M. scrofulaceum strains which had the faster-migrating activity band were inhibited 100% after only 5 min of exposure to 5 mM H2O2 and exhibited greater sensitivity to 5 and 10 mM NaN3, characteristics of an iron-containing SOD. A concentration of 1 mM KCN did not cause inhibition of enzyme activity in any of the MAIS strains tested. Extracellular SOD activity was detected in four of six MAIS strains and was shown to be identical in mobility to the SOD activity of the crude extracts.
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PMID:Superoxide dismutase activity of Mycobacterium avium, M. intracellulare, and M. scrofulaceum. 374 55

The effect of some components of the medium on the growth of Mycobacterium cyaneum B-646 and on the biosynthesis of an exoglycan by the culture was studied. A medium in which the M. cyaneum M variant produced up to 2.2 g of the exopolysaccharide per litre, which was nearly 4 times more than in the original medium, was proposed. The new medium differed from the original one in an elevated content of carbon, iron and potassium (11.2, 5.0 and 1.4 times, respectively) and in a lower phosphorus content (6.7 times). The exopolysaccharide produced by the culture in this medium contained glucose, galactose, fucose and uronic acid. Therefore, its monomeric composition did not depend on the medium used for growing the culture which produced the exopolysaccharide.
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PMID:[Optimization of a medium and the role of its various components for the biosynthesis of Mycobacterium cyaneum exopolysaccharide]. 377 95

During one year, 55 bone marrow biopsies from 49 patients with CDC-defined acquired immune deficiency syndrome (AIDS) were studied. Eighty-three percent were normocellular or hypercellular; 17% were hypocellular. Marrow plasma cells were increased in 83% of patients, most showing polyclonal hypergammaglobulinemia. Forty percent of patients showed peripheral neutropenia, 29% thrombocytopenia, and 79% lymphopenia with markedly reduced T4+ lymphocytes. Eighty-five percent of patients were anemic, with iron studies showing a pattern consistent with the anemia of chronic disease. Mycobacterium avium-intracellulare (MAI) grew from ten (20%) biopsies, four with granuloma and six without granuloma (five of these six also showed marrow hypocellularity). Small poorly formed granuloma (70-150 micron) were seen in eight (16%) patients (four AFB-culture positive, 4 negative). Three of four granuloma-positive, culture-negative cases eventually grew MAI from autopsy material. Five (10%) patients had lymphoplasmacytic aggregates; later, one developed lymphoma, another, markedly atypical lymphoid hyperplasia. Two additional patients showed marrow B-cell lymphomas. Of these findings, only marrow MAI meets the CDC definition of AIDS. However, in this series, small ill-defined granulomas, lymphoplasmacytic aggregates, and B-cell lymphomas also were found. The authors conclude that these latter findings, when seen in high-risk patients, particularly those with lymphopenia, anemia, and/or hypergammaglobulinemia, also strongly suggest the diagnosis of AIDS.
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PMID:The bone marrow in AIDS. A histologic, hematologic, and microbiologic study. 403 75

Mycobactins were isolated from five strains designated Mycobacterium farcinogenes and a similar number designated Mycobacterium senegalense following growth under conditions of iron-limitation. These lipid-soluble iron-chelating compounds were characterized by a combination of thin-layer and high-performance liquid chromatography. The mycobactins from both the slow-growing M. farcinogenes and the rapidly-growing M. senegalense strains proved impossible to differentiate both from each other and from those produced by strains of Mycobacterium fortuitum, indicating a close relationship between all three species. However, Nocardia farcinica, previously implicated with the bovine farcy strains, produced a different mycobactin which was easily distinguished by thin-layer chromatography alone.
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PMID:Equivalence of mycobactins from Mycobacterium senegalense, Mycobacterium farcinogenes and Mycobacterium fortuitum. 404 24

Methods were devised to purify the cell-associated, iron-binding compounds known as mycobactins from the closely related species Mycobacterium avium, Mycobacterium intracellulare, and Mycobacterium scrofulaceum (i.e., the MAIS complex of organisms). The mycobactins from these three species showed a structure that is common to the mycobactins from all the mycobacteria examined to date. However, these mycobactins were unique in that they had more than one alkyl chain. The M. scrofulaceum mycobactins differed from other MAIS mycobactins by a shift in the position of the double bond in the R1 alkyl chain. Traces of other mycobactin types were observed in ethanol extracts of the three species, and examination of the chromatographic properties of these mycobactins showed that each species produced five mycobactin types. Each mycobactin could be subdivided further by the length of its R1 alkyl chain. No differences in the production of these novel mycobactin were observed among species. Mycobactins from three strains of Mycobacterium paratuberculosis and two wood pigeon strains of Mycobacterium avium which had lost their original growth requirements for mycobactin after repeated subculturing in laboratory growth media were examined by thin-layer chromatography and high-pressure liquid chromatography. Each organism produced a mycobactin with similar chromatographic properties to those synthesized by MAIS organisms. M. paratuberculosis NADC 18 produced at least two components in our laboratory, and nuclear magnetic resonance analysis of the major component showed this mycobactin to be identical to that produced by M. intracellulare M12. However, a sample of mycobactin J isolated by Merkal and McCullough (Curr. Microbiol. 7:333-335, 1982) from M. paratuberculosis NADC 18 was different from our isolates and appeared to correspond to a minor mycobactin component we had seen by thin-layer chromatography. No reason for this difference could be evinced. Our findings indicate that there is a close taxonomic relationship between M. paratuberculosis and the MAIS complex.
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PMID:Isolation, identification, and structural analysis of the mycobactins of Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium scrofulaceum, and Mycobacterium paratuberculosis. 405

Surface paper strips containing hemin (X factor) were tested on Middlebrook 7H10 agar and Lowenstein-Jensen medium to determine if the growth requirement of Mycobacterium haemophilum for iron-containing complexes could be met by this simplified method. One reference strain and seven strains of this species isolated from patients showed good growth around the strips on 7H10 within 2 weeks but failed to grow on Lowenstein-Jensen medium with X-factor strips. Middlebrook 7H10 medium with X-factor strips may be a useful alternative to the preparation of specialized media for the recovery of M. haemophilum from clinical specimens.
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PMID:Evaluation of a simple method for growing Mycobacterium haemophilum. 405 14

Mycobacterium smegmatis was grown on trace-metal-free medium in static culture. Throughout the growth phase, the concentration of mycobactin increased continuously, reaching a maximum of about 30 to 40 mug of mycobactin/mg of cell dry weight after 6 days; the concentration of salicylic acid remained approximately constant at 1 to 2 mug of salicylic acid/mug of cell dry weight. Fe(2+) (or Fe(3+)), Zn(2+), Mn(2+), and Mg(2+) were all essential to a maximum formation of mycobactin. Optimum concentrations required were: Fe(2+), about 1.8 mum; Mn(2+) and Zn(2+), about 0.5 mum; and Mg(2+), at least 0.17 mm. Higher levels of Fe(2+) (9 to 90 mum) and Zn(2+) (2 to 7 mum) repressed mycobactin to about half the maximum value. No other cation or anion apparently is required for mycobactin biosynthesis. Salicylic acid concentration increased about fourfold when iron was omitted from the medium, but this is not as great as the increase reported previously for this strain of M. smegmatis. Mycobactin formation in another strain of M. smegmatis, NCIB 8548, showed similar dependencies on Fe(2+), Zn(2+), and Mn(2+). Maximum accumulation of mycobactin with this strain was 85 mug of mycobactin/mg of dry cell weight, under iron-deficient (1.8 mum Fe(2+)) conditions.
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PMID:Influence of metal ions on the formation of mycobactin and salicylic acid in Mycobacterium smegmatis grown in static culture. 494 61

Nine different strains of mycobacteria grown on media deficient in iron all produced mycobactins. Most strains produced one mycobactin in great preponderance. Mycobacteria from clearly distinct taxonomic groups gave mycobactins differing in the structure of their nuclei. One group of taxonomically related mycobacteria produced mycobactins having the same nucleus but with different distributions of side chains within the homologous mixtures. Simple methods are described for identifying mycobactins on a small scale; these may be of value in classifying mycobacteria. Structures are proposed for mycobactin A from Mycobacterium aurum, mycobactin R from M. terrae, mycobactin F, produced together with mycobactin H by M. fortuitum, and mycobactins M and N from M. marinum. The first three of these differ from known mycobactins in details of substitution and configuration of asymmetric centres in the nucleus. Mycobactins M and N are substantially different, having only small acyl groups (acetyl and propionyl respectively) at the hydroxamic acid centre of the mycobactic acid moiety. Both are homologous mixtures having long-chain saturated 3-hydroxy-2-methyl acid fragments in the cobactin moiety. All mycobactins so far isolated promote almost maximal growth of M. johnei at 30ng./ml. in liquid medium. The activity of some mycobactins extends to much lower concentrations, mycobactin S showing significant growth promotion at 0.3ng./ml. Mycobactin M or N in combination with mycobactins having a long side chain in the mycobactic acid moiety exerts a mutually antagonistic effect on the growth of M. johnei, the mixture giving less growth than either mycobactin separately. Mycobactin M also decreases the growth of M. kansasii and M. tuberculosis on liquid media. These antagonistic effects are probably caused by a lengthening of the lag phase.
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PMID:Chemical and biological properties of mycobactins isolated from various mycobacteria. 536 Jun 74

Crystalline gallium mycobactin P and chromic mycobactin P have been prepared. The chromic compound, unlike other metallic complexes of mycobactin P, does not detectably exchange its metal with ferric iron; it competitively antagonizes the growth-promoting action of mycobactin P towards Mycobacterium johnei. Mycobactin P, desferrioxamine B and desferrichrysin form coloured 1:1 complexes with ammonium vanadate. The vanadyl complexes of the water-soluble desferrisideramines are formed in aqueous solution. Two distinct forms occur at pH7 and pH3; these are slowly interconvertible when the pH is changed. The complexes show other changes at lower pH values; unlike other metallic desferrisideramine complexes, the vanadyl compounds do not dissociate even in the strongest acids, but dissociate above pH9. Their properties have been studied spectrophotometrically, by electrophoresis and by electrometric titration. The affinity of mycobactin for ferric iron is greater than that of desferrioxamine B under two different conditions of measurement.
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PMID:Metal complexes of mycobactin P and of desferrisideramines. 537 79


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