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

A new non-phosphorylated lipoamino acid was extracted from Mycobacterium phlei, strain IST. It is particularly sensitive to alkaline hydrolysis, and contains a lysine residue joined to a 1,2-diglyceride via an ester linkage. The FAB-positive mass spectrum shows the presence of various molecular species of which the most abundant contains a palmitic and a tuberculostearic acid residue. An analogue of this lipid was synthesized, 1,2-dipalmitoyl 3-lysyl glycerol. Both its chromatographic behavior (TLC), and the decomposition pathways of the MH+ ions, studied by FAB MS and MIKE spectroscopy, were identical to the natural product.
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PMID:Isolation and structural characterization of a new non-phosphorylated lipoamino acid from Mycobacterium phlei. 324 May 62

A comparative study of factors of activation and stabilization of individual DNA-methylases from two bacterial strains--Shigella sonnei 47 and Mycobacterium smegmatis butyricum--isolated by isoelectrofocusing in a pH gradient has been carried out. Storage of enzymes at +4 degrees C (pH 7.5) is accompanied by periodic changes in the methylating activity. No such changes are observed when the enzymes are stored at pI of the protein. In this case the methylases with alkaline or close to neutral values of pI remain stable over a period of at least two weeks, whereas acidic proteins are irreversibly inactivated by the end of a two-week period. A stabilizing effect of BSA on DNA-methylases of Sso 47 and Mbu strains has been demonstrated. A direct correlation between the stabilizing effect of BSA and the degree of enzyme purity has been established. Ca2+ appear to be a universal activator of methylases of the above strains; these cations produce a potent, although a short-term effect and can be used in the production of enzyme preparations with a high specific activity in DNA recombinant technology. Protease inhibitors do not exert any appreciable effect on the methylase activity upon storage. Storage at -20 degrees C and at neutral pH leads to complete inactivation of all DNA-methylases within 24 hours. In this case glycerol is fairly ineffective as a stabilizing agent.
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PMID:Factors of activation and stabilization of DNA-methylases from Shigella sonnei 47 and Mycobacterium smegmatis butyricum cells. 333 Oct 85

Deoxypheganomycin D, a specific inhibitor of mycobacteria, inhibits the growth in vitro of Mycobacterium smegmatis ATCC 607 (M. 607) bacteriostatically at concentrations as high as 7 X 10(-5) M. It shows no cross-resistance to paromomycin, capreomycin, viomycin, streptothricin, kanamycin and streptomycin. Deoxypheganomycin D at 2.8 X 10(-7) M where the cell growth of M. 607 is only partially inhibited does not significantly inhibit DNA, RNA or protein synthesis but leads to marked decrease (13% of control) in [14C]glycerol-derived radioactivity in cell-walls. In the presence of 7 X 10(-6) M deoxypheganomycin D, the influx of leucine but not thymidine is affected while the reverse is true with efflux. The data suggest that the effect of deoxypheganomycin D on M. 607 may be related to both the cell membrane and specific mycobacterial lipid like components of the cell-wall.
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PMID:Mode of action of deoxypheganomycin D on Mycobacterium smegmatis ATCC 607. 338 53

Pyrimidine biosynthesis and its regulation in the presence of different carbon and nitrogen sources in the growth medium of Mycobacterium smegmatis were studied. M. smegmatis TMC 1546 cells grown in shake culture were found to have marginally higher pyrimidine enzyme biosynthesis activities than cells grown in static culture. The activity was highest at the mid-log phase of growth during both surface and shake cultures, suggesting that the cells were metabolically most active at this stage of growth. Replacement of glycerol by glucose and fructose slightly increased the activities of carbamyl phosphate synthetase and aspartate transcarbamylase. The enzyme activities involved in pyrimidine biosynthesis decreased when citrate was replaced by succinate, fumarate, pyruvate or acetate in the growth medium. The activities of the enzymes in pyrimidine biosynthesis were found to decrease when asparagine as a nitrogen source in the medium was replaced by glutamate, glutamine or ammonium chloride. The presence of ornithine in place of asparagine in the growth medium increased these enzyme activities, while the presence of arginine instead of asparagine in the growth medium decreased these enzyme activities, though the differences in activity were small. The activity of aspartate transcarbamylase in vitro was inhibited by arginine. In the case of cells grown in the presence of ornithine, the activity of aspartate transcarbamylase was induced by ornithine, but inhibited by arginine.
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PMID:Role of various carbon and nitrogen sources in the regulation of enzymes of pyrimidine biosynthesis in Mycobacterium smegmatis TMC 1546. 344 89

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

Mycobacterium bovis (BCG) was submitted to lipid extraction involving gentle and drastic procedures. Neutral lipids, glycolipids as well as phospholipids were detected in the diethyl ether extract, whereas the chloroform and chloroform-methanol extracts contained mainly phospholipids. Arabinose mycolates, which represent firmly bound cell wall lipids, were detected in the acidified ether extract. The lipid extracts were adsorbed to charcoal particles and inoculated intravenously into mice. Histological analysis showed that the particles were trapped in the lung microcirculation and strong inflammatory reactions were induced around the charcoal particle coated lipids present in the diethyl ether, chloroform and acidified diethyl ether extracts. Fractionation of these inflammation-inducing extracts by column and preparative thin-layer chromatography led to the isolation of five active mycolic acid-containing glycolipids, identified as glycerol monomycolate, glucose monomycolate, arabinose monomycolate, trehalose monomycolate and trehalose dimycolate on the basis of physical, chemical and spectroscopic analyses. Inflammatory reactions similar to that observed after inoculation of live BCG were induced in the lungs by trehalose monomycolate, trehalose dimycolate or glucose monomycolate. However, the toxic reactions caused by glycerol monomycolate and arabinose monomycolate were characterized by an acute inflammatory process mainly due to the constant and massive presence of polymorphonuclear leukocytes.
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PMID:Inflammation induced by mycolic acid-containing glycolipids of Mycobacterium bovis (BCG). 391 15

Cerulenin inhibited the lipid synthesis of Mycobacterium smegmatis ATCC 607 over the range of 0.5-1.8 microgram/mL with complete inhibition at 1.8 microgram/mL, as monitored by [14C]glycerol incorporation into lipids. Exogenous fatty acids failed to restore the lipid synthesis at 1.8 microgram/mL; however, the addition of palmitic acid to the growth medium partially restored the lipid synthesis when cerulenin concentration was decreased to 1.6 microgram/mL. Fatty acid analysis of cerulenin plus palmitic acid supplemented cultures revealed that exogenously supplied fatty acid was incorporated into cellular phospholipids. Further investigations with 1.6 microgram/mL of cerulenin and [14C]acetate and [32P]orthophosphoric acid showed that cerulenin inhibited the synthesis of saturated plus unsaturated fatty acids and phospholipids. Pulse-chase studies with [14C]acetate revealed decreased synthesis and degradation of each of the phospholipid components.
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PMID:Cerulenin inhibition of lipid synthesis and its reversal by exogenous fatty acids in Mycobacterium smegmatis ATCC 607. 399 6

A sensitive and nondestructive radiometric method has been applied to the detection of metabolism of Mycobacterium lepraemurium, as a model for the study of the metabolism and substrate requirements of M. leprae. The method is based on the measurement of the (14)CO(2) produced through the bacterial conversion of [U-(14)C]acetate or [U-(14)C]glycerol by 7 x 10(9) bacteria suspended in 10 ml of either a simple buffer system (K-36) or a complex medium (NC-5). Metabolism of the bacilli was easily detected within 3 days after inoculation and was measured daily. NC-5 medium supported metabolism of M. lepraemurium for several weeks longer than the simple K-36 buffer. The radiometric technique shows promise as a rapid and efficient system for evaluating the metabolism of mycobacteria without introducing any changes in the physiologic state of the organisms, studying their metabolic pathways, determining conditions potentially favorable for multiplication of these organisms in vitro, and studying their susceptibility to inhibition by drugs.
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PMID:Radiometric measurement of metabolic activity of Mycobacterium lepraemurium. 460 79

A particulate enzyme preparation from Mycobacterium smegmatis catalyzes the transfer of [(14)C]galactose from uridine 5'-diphosphate (UDP)-[(14)C]galactose and of [(14)C]glucose from UDP-[(14)C]glucose into chloroform-soluble products. The radioactive neutral lipids were purified by passage through diethylaminoethyl-cellulose, followed by thin-layer chromatography. When UDP-glucose was used as substrate, two major radioactive lipids were obtained; one had a hexose-glucose-glycerol ratio of 1:1:1. The second product had a hexose-glycerol ratio of 2:1 and, in addition to glucose, contained lesser amounts of mannose and galactose. With UDP-galactose as substrate, two radioactive products were observed that were chromatographically indistinguishable from the [(14)C]glucosyl-labeled mono- and diglycosyldiglyceride. Palmitate and oleate were the predominant fatty acid constituents in these lipids and were present in equimolar amounts in all of the products examined. The products have thus been identified as monoglycosyldiglyceride and a diglycosyldiglyceride containing glucose as the major hexose along with mannose and galactose. Properties of the galactosyl and glucosyl transferases are described.
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PMID:Biosynthesis of glycosyldiglycerides in Mycobacterium smegmatis. 480 95

1. Mycobacterium tuberculosis BCG was usually grown in glycerol-asparagine-casein hydrolysate medium. A soluble fraction was obtained from the cells with aq. 50% ethanol; unbound lipids were then removed and the cells were treated with dilute alkali to give, after acidification, an alkali-extractable fraction and an insoluble fraction. On occasion, lipopolysaccharides were obtained by extracting with phenol or dimethyl sulphoxide instead of alkali. The soluble fraction contained, particularly after long extraction, polysaccharide containing mainly glucose, in addition to trehalose and monosaccharides and their derivatives. The alkali-extractable fraction contained polysaccharides containing mannose, glucose, arabinose, galactose and 6-O-methylglucose. These could be resolved into three fractions of markedly different molecular size. It is argued that the high-molecular-weight materials originated from the outside of the cell envelope and the medium-molecular-weight materials from a middle layer of the envelope. 2. Exposure of the growing cells to isoniazid, usually at 1 or 10mug/ml for 6-12h, increased the total cell carbohydrate, mainly due to an increase in trehalose and in insoluble glucan. It also facilitated the extraction of polysaccharide into the medium and the soluble fraction. This produced about a 25% decrease in the amount of carbohydrate in the alkaline-extractable fraction, mainly due to a fall in glucose, arabinose and 6-O-methylglucose. The decrease was confined to polysaccharides of large and medium molecular weight. When intact lipopolysaccharides were extracted, their amount was also decreased by isoniazid. 3. Substitution of ammonium sulphate for asparagine and casein hydrolysate in the medium, so that glycerol was the sole carbon source, decreased the carbohydrate accumulation brought about by isoniazid but did not alter its effect on polysaccharide extraction. 4. Growth with (14)C-labelled substrates showed that glycerol provided two to four times as much of the cell carbon as did asparagine, when both were present. Under these conditions isoniazid inhibited the incorporation of carbon atoms from asparagine into the cells, but had little effect on the total incorporation from glycerol. These experiments also showed that the effect of isoniazid on alkali-extractable polysaccharides was due to their loss to the soluble fraction and external medium. 5. It is suggested that isoniazid inhibits a pathway (probably the synthesis of mycolic acid) involved in the formation of the cell envelope, and that this inhibition results in some re-channelling of intermediates into carbohydrate synthesis and in some loss of polysaccharides through damage to the envelope.
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PMID:The effects of isoniazid on the carbohydrates of Mycobacterium tuberculosis BCG. 491 50


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