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

Mycobacterium tuberculosis has been found to exhibit autolysis and spontaneous secondary growth in modified Sauton medium. The phenomenon is a function of high glycerol concentration of the medium and limitation of air in test tubes. It is not a function of depletion of nutrients and is probably not a manifestation of lysogeny or spheroplast formation. The cycle of growth, autolysis, and secondary growth is related to development of lethal conditions during a period of severe oxygen limitation followed by a metabolic change associated with slower depletion of glycerol.
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PMID:Autolysis and secondary growth of Mycobacterium tuberculosis in submerged culture. 496 59

Ornithinyl ester of phosphatidyl glycerol was found to accumulate in Mycobacterium 607 under acidic conditions (pH 5.6) of growth or in cultures of ultraviolet-irradiated (320 to 420 nm) bacilli. There was a corresponding decrease in cardiolipin content of the organisms under these conditions.
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PMID:On the ornithinyl ester of phosphatidylglycerol of Mycobacterium 607. 541 6

A basic difference was found in the kinetics of uptake and utilization of glucose and glycerol by washed suspensions of Mycobacterium phlei. With glucose, the rates of uptake, respiration, and assimilation were saturated at low external substrate concentration. With glycerol, these rates were found to increase with increasing substrate concentration and did not show saturation at any concentration tested. Qualitatively similar patterns were observed for cells grown on either glycerol or glucose. Above a saturation concentration, ratios of cell (14)C to CO(2) (14)C for uniformly labeled (14)C-glucose were constant at a value of 0.96. Glycerol-U-(14)C, on the other hand, yielded cell-(14)C/CO(2)-(14)C ratios which were highest at the lowest glycerol concentration tested, and decreased with increasing substrate concentration. The distribution of the glucose and glycerol carbons assimilated into M. phlei were qualitatively similar. Quantitatively, however, the uptake and assimilation of glycerol was far more rapid than that of glucose for all substrate concentrations employed. These quantitative differences in the utilization of glycerol and glucose could account for the increased content of nonessential lipid and polysaccharide found in glycerol-grown M. phlei.
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PMID:Differences in the utilization of glycerol and glucose by Mycobacterium phlei. 565 78

Successful growth of Mycobacterium lepraemurium was observed in cultures of mouse peritoneal macrophages. The optimal host cell maintenance medium was composed of 40% horse serum, 50% of the chemically defined medium NCTC 109, and 10% of a 1:5 dilution of beef embryo extract, supplemented with both liver extract and ferric nitrate. Multiplication of the bacilli was observed in 1 week and maximal growth in 6 to 7 weeks. All macrophages were filled with tens to hundreds of the organisms in cultures showing maximal growth. Glycerol caused an increase in the normal length of M. lepraemurium, without a corresponding increase in the number of the bacilli. Elongation of M. lepraemurium was observed 3 or 4 days after infection. Rapid and uniform growth of M. lepraemurium was achieved in serially transferred cultures (subcultures). The cumulative increase of the number of intracellular bacilli was 1.4 x 10(20)-fold in 14 transfers over a period of 68 weeks in one series, and 10(17)-fold in 12 transfers over a period of 56 weeks in another series. The generation time of M. lepraemurium was 7 days, a growth rate which approximates the fastest growth of the organisms in vivo. Organisms harvested from cultures at various stages of growth produced murine leprosy in mice, but showed no growth in bacteriological media. The present model offers an opportunity for studies on the host-parasite relationship without the complication of extracellular growth of the parasites.
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PMID:Growth of Mycobacterium lepraemurium in cultures of mouse peritoneal macrophages. 602 17

1. When growing Mycobacterium tuberculosis BCG was exposed to 0.5-10mug. of isoniazid/ml. there was intracellular accumulation of soluble carbohydrate, combined phosphate and substances absorbing at 260mmu. Yellow pigments were formed when modified Sauton medium was used, but not with Proskauer & Beck medium. These processes were apparent after 1hr. but were more marked after about 6hr. These effects were not found with an isoniazid-resistant strain. 2. After 6hr. exposure of the sensitive strain to 10mug./ml. there was little change in the amounts (per g. of insoluble nitrogen) of total lipid, glycolipid, RNA, DNA or of carbohydrate in the nucleic acid fractions. 3. The major accumulation was of alphaalpha'-trehalose. There was also accumulation of glucose 6-phosphate, glucose 1-phosphate, fructose 6-phosphate, trehalose 6-phosphate (tentatively identified), a polysaccharide containing only glucose, and an oligosaccharide containing glucose and glucose 6-phosphate, but not of glycerol and glycerol 3-phosphate. The u.v.-absorbing materials appeared to be nucleotide sugar derivatives. 4. In Mycobacterium smegmatis a similar accumulation of trehalose occurred on exposure to isoniazid, but there was little accumulation of other compounds. 5. No evidence could be found that isoniazid specifically affected the oxidation of glycerol or glycerol 3-phosphate. 6. It is suggested that the primary action of isoniazid on mycobacteria may be partial inhibition of a reaction in some central area of metabolism, such as glycolysis.
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PMID:Effects of isoniazid on the composition of mycobacteria, with particular reference to soluble carbohydrates and related substances. 604 80

Glutamine synthetase from a Gram-positive acid-fast bacterium, Mycobacterium smegmatis, was purified to homogeneity from cells grown with glycerol-bouillon medium. Electron micrographs of the enzyme revealed a dodecameric arrangement of its subunits in two superimposed hexagonal rings, similar to the structure of glutamine synthetase of Escherichia coli. Disc electrophoresis in the presence of sodium dodecyl sulfate indicated a subunit molecular weight of 56,000. The sedimentation coefficient of the native enzyme was estimated to be 19.4S by ultracentrifugation in a sucrose gradient. Like the E. coli enzyme, the glutamine synthetase from M. smegmatis is regulated by adenylylation/deadenylylation. This conclusion was based on studies of the effect of snake venom phosphodiesterase treatment on the catalytic and spectral properties of the isolated enzyme. The AMP released from the enzyme by the phosphodiesterase was identified by thin-layer chromatography. Despite the structural similarity of both enzymes, striking differences were found between the catalytic properties of M. smegmatis and E. coli glutamine synthetases. The divalent cation specificity of the M. smegmatis enzyme was not altered by adenylylation of the enzyme, and deadenylylation of the enzyme caused a significant increase in the specific activities for both biosynthetic and transfer reactions with either Mg2+ or Mn2+.
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PMID:Regulation of Mycobacterium smegmatis glutamine synthetase by adenylylation. 614 40

Mycobacterium lepraemurium was cultivated on Ogawa egg-yolk medium and its respiratory activities using several substrates were investigated. Glycerol and succinate were oxidized at a slow rate by the cell-free extracts prepared from in vitro grown Hawaiian and Keishicho strains of M. lepraemurium. None of the other intermediates of the glycolysis cycle as well as of the tricarboxylic acid cycle was oxidized by the whole cell suspensions or cell-free extracts. Likewise, many sulfur compounds such as cystine, mercaptosuccinate, monothioglycerol, thioacetate, etc., were inactive. However, sulfhydryl compounds such as L-cysteine, D-cysteine, DL-cysteine, dithioerythritol, dithiothritol, and DL-penicillamine were actively oxidized. Yeast extract was also readily oxidized by cell suspensions of in vitro grown M. lepraemurium. Tween 80 was very poorly oxidized by whole cell suspensions but the cell-free preparations catalyzed an active oxidation of Tween 80. While bovine serum albumin was oxidized at a slow rate by cell-free extracts, egg albumin was inactive. The thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide were effective inhibitors of succinate and NADH oxidation, thus indicating the involvement of sulfhydryl compounds in the metabolism of M. lepraemurium.
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PMID:Respiratory activities of in vitro grown Mycobacterium lepraemurium. 634 13

With radioisotopes, it was shown that suspensions of Mycobacterium leprae oxidized glycerol, 6-phosphogluconate, glucose, glucose 6-phosphate, and, at a low rate, gluconate, to CO2. The incubation period in these experiments was usually 20 h, but after 140 h up to five times more glucose and gluconate had been converted to CO2. Studies with differentially labelled glucose indicated that glycolysis and the hexose monophosphate pathway were used for glucose dissimilation. Key enzymes of glycolysis, the hexose monophosphate pathway and glycerol catabolism were detected in cell-free extracts from purified M. Leprae, but phosphoketolase, Entner-Doudoroff pathway activity and gluconate kinase were absent. All these enzymes were present also in host-tissue, but biochemical evidence is presented which indicates that all enzymes detected in extracts from M. leprae were authentic bacterial enzymes. Additionally, they could all be detected in extracts of M. leprae prepared by treatment with NaOH in which host enzymes adsorbed to M. leprae are inactivated.
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PMID:Catabolic pathways for glucose, glycerol and 6-phosphogluconate in Mycobacterium leprae grown in armadillo tissues. 635 57

Four disease-associated strains of Mycobacterium avium-intracellular isolated in our laboratory from human sputum gave rise to transparent, opaque, intermediate, and rough colony forms on cornmeal glycerol medium. Each colony-former was purified, and both the virulence to conventional ddY strain of mice and in vitro susceptibilities to various antimicrobial drugs were compared among different colony-formers. The opaque colony-formers were more susceptible to cephalothin, rifampicin, gentamicin, tobramycin, and kanamycin than the other colony-formers. Simultaneous evaluation of virulence to the mice revealed both opaque and intermediate colony-formers to be less virulent than transparent and rough colony-formers.
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PMID:Various colony-formers of Mycobacterium avium-intracellulare. 646 43

Arginine biosynthesis and its regulation by the presence of different carbon and nitrogen sources in the growth medium of Mycobacterium smegmatis was studied. Replacement of glycerol by glucose and fructose increased the activities of acetylglutamate kinase, acetylornithinase and ornithine transcarbamylase and the enzyme activities of the arginine biosynthetic pathway. The presence of succinate, fumarate, pyruvate or acetate in the growth medium (replacement for citrate) also increased these enzyme activities. However, when glutamate or glutamine was used as nitrogen source in place of asparagine, the enzyme activities decreased. The presence of ornithine or arginine in the growth medium repressed these enzyme activities, though the degree of repression was slight. The phenomenon of repression by arginine and ornithine was confirmed by dialysis experiments. Arginine inhibited the ornithine transcarbamylase activity from cells grown with asparagine as nitrogen source, but activated it when the cells were grown with arginine. Thus, in addition to the weak transcriptional control of arginine biosynthetic enzymes, feedback regulation of ornithine transcarbamylase by arginine also regulated arginine biosynthesis in M. smegmatis grown with asparagine as nitrogen source.
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PMID:Influence of carbon and nitrogen sources on arginine biosynthesis in Mycobacterium smegmatis ATCC 14468. 650 73


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