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Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At dissolved oxygen tensions of 15 mmHg (2 kPa) and below, nitrate-limited continuous cultures of Klebsiella K312 synthesized nitrate reductase (NR) and nitrite reductase (NiR) and excreted ammonia. Under anaerobic conditions over 60% of the nitrate-nitrogen utilized was excreted as ammonia. In contrast, carbon-limited cultures excreted nitrite at dissolved oxygen tensions of 15 mmHg or below and synthesized NR but not NiR. Ammonia repressed neither NR nor NiR synthesis. These observations indicate that below a critical oxygen tension of 15 mmHg Klebsiella K312 utilizes oxygen and nitrate as electron acceptors. This oxygen tension correlates well with the critical oxygen tension observed for a change from oxidative to fermentative metabolism in cultures of Klebsiella aerogenes. The product of dissimilatory nitrate reduction is ammonia in nitrate-limited cultures but principally nitrite in carbon-limited (nitrate excess) cultures.
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PMID:Influence of oxygen tension on nitrate reduction by a Klebsiella sp. growing in chemostat culture. 47 38

Fours strains of nitrate reducing bacteria isolated from soil were studied for their behavior towards chlorate. They are facultative anaerobes, except for Bacillus megatherium (which is a strict aerobe) and they possess a nitrate reductase A. The growth of three strains of bacteria (Klebsiella pneumoniae, B. licheniformis and Micromonospora globosa) was slowed by sodium chlorate at a concentration of 0.06 to 0.1% while the other strain (B. megatherium) tolerated the CIO3- well. The delay of bacterial growth due to chlorate lasts for a certain period, after which the bacteria multiply again. The lag phase is due to small quantities of chlorite produced from the chlorate; the growth phase which follows is provoked by the multiplication of chlorate resistant mutants, most often nitrate reductase-negative and sometimes positive. Some reverse mutants nitrate reductase positive of K. pneumoniae no longer had the same characteristics as the wild strain: some resisted to chlorate or were different as to gas formation. The reduction of nitrate to ammonia by these bacteria is diminished in the presence of chlorate: the reduction of nitrate to nitrite was inhibited or not inhibited according to the type of strain. The bacteria broke down the chlorate partially or completely, according to the strains and the sustrates.
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PMID:[A study of the action of sodium chlorate on strains of nitrate reducing soil bacteria (author's transl)]. 48 91

Tests with 140 strains representing Escherichia coli, Klebsiella aerogenes, K. ozaenae, Proteus mirabilis, P. vulgaris, P. rettgeri and P. morganii in a defined medium supplemented with 0-09M dimethylamine (DMA) and 0-1M potassium nitrate showed that at least 89% of the 136 strains able to reduce nitrates produced up to 9mM dimethylnitrosamine (DMN) in 70h at 37 degrees C. Four nitratase-negative strains produced DMN from DMA in the presence of sodium nitrate. Prolonged incubation was the most important factor in determining DMN production. Stasis and persistent infection in the urinary tract, by simulating prolonged incubation of a culture, may be of importance in determining whether the potential carcinogen, DMN, could be produced in vivo by bacterial action on DMA and nitrate in urine.
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PMID:The importance of prolonged incubation for the synthesis of dimethylnitrosamine by enterobacteria. 77 90

When cell-saturating amounts of glucose and phosphate were added to steady state cultures of Klebsiella aerogenes that were, respectively, glucose- and phosphate-limited, the organisms responded immediately with an increased oxygen consumption rate. This suggested that in neither case was glucose transport the rate-limiting process, and also that organisms must possess effective mechanisms for spilling the excess energy initially generated when a growth-limitation is temporarily relieved. Steady state cultures of mannitol- or glucose-limited organisms also seemingly generated energy at a greater rate than was required for cell synthesis since gluconate-limited cultures consumed oxygen at a lower rate, at each corresponding growth rate, than did mannitol- or glucose-limited cultures, and therefore expressed a higher YO value. Thus, mannitol- and glucose-limitations must be essentially carbon (and not energy) limitations. The excess energy generated by glucose metabolism is one component of "maintenance" and could be used at lower growth rates to maintain an increased solute gradient across the cell membrane, imposed by the addition of 2%, w/v, NaCl to the growth environment. The maintenance rates of oxygen consumption of K. aerogenes also could be caused to increase by adding glucose discontinuously (drop-wise) to a glucose-limited chemostat culture, or by exchanging nitrate for ammonia as the sole utilizable nitrogen source. The significance of these findings to an assessment of the physiological factors circumscribing energy-spilling reactions in aerobic cultures of K. aerogenes is discussed.
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PMID:The role of energy-spilling reactions in the growth of Klebsiella aerogenes NCTC 418 in aerobic chemostat culture. 101 53

Exopolysaccharides interfere with the isolation and characterization of plasmid DNA from gram-negative bacteria. To repress capsular polysaccharide production, bacteria were cultured in medium containing bismuth nitrate and sodium salicylate. Rapid removal of other contaminating bacterial surface components was achieved by mild acidic zwitterionic detergent extraction. After treatment, bacterial cells were more readily lysed in alkaline detergents. The resulting plasmid preparations contained virtually no capsular polysaccharide and relatively small quantities of lipopolysaccharide and protein, yet they produced yields of nucleic acids similar to those of conventional plasmid preparations. Conventional preparations from encapsulated organisms were largely insoluble and appeared as smears following agarose gel electrophoresis, with indefinite plasmid banding. Plasmids prepared by the new method were highly soluble in conventional buffers and exhibited high-resolution plasmid banding patterns in agarose gels. Plasmids as large as 180 kbp could be isolated and visualized, without apparent nicking, and were readily digested by restriction endonuclease enzymes. The method proved effective with encapsulated or mucoid strains of Klebsiella pneumoniae, Escherichia coli, Acinetobacter anitratus, Salmonella typhimurium, and Enterobacter species. The complete method for plasmid isolation was not suitable for Pseudomonas aeruginosa because of the inhibitory effects of bismuth. Thus, removal of contaminating bacterial surface structures enabled the rapid isolation and characterization of plasmids from mucoid clinical isolates, without the use of organic solvents, CsCl gradients, or expensive, disposable columns.
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PMID:Rapid plasmid DNA isolation from mucoid gram-negative bacteria. 133 82

The expression under microaerobic conditions of the Rhizobium meliloti nifA and consequently the nifHDK genes was found to be negatively regulated by ammonia and nitrate. Assimilation of the ammonia to glutamate and glutamine is not required for this regulation to occur. This indicates that ammonia itself, and not a product of its metabolism, may be regulating nif expression. Unlike the situation in Klebsiella pneumoniae, NtrC is apparently not involved in mediating the ammonia effect on nifA expression in R. meliloti. Neither does the fixK gene product, which is known to regulate nifA in R. meliloti, appear to be involved in mediating the ammonia effect. The regulation of nifA by ammonia is shown to be mediated through the FixL protein. A truncated fixJ gene, the product of which has been shown to induce nifA expression irrespective of the oxygen status of the cell, also circumvented the repressive effect of ammonia on nifA expression. This suggests that the ammonia effect is mediated through the FixLJ regulatory cascade. Interestingly no effect of ammonia on fixK expression was observed.
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PMID:Ammonia regulation of the Rhizobium meliloti nitrogenase structural and regulatory genes under free-living conditions: involvement of the fixL gene product? 140 87

A silver-resistant mutant of Klebsiella pneumoniae B-5 was produced by passaging in nutrient broth containing graded concentrations of silver nitrate up to 150 ppm. The development of silver resistance in the strain resulted in rough colonies, decrease in cell size, carbohydrate content and change in klebocin pattern. The virulence of the AgR strain as checked by the burn wound model decreased as the mutant could not establish itself in the skin and spleen of the animals and the organism was cleared more efficiently by human lymphocytes than the parent AgS strain.
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PMID:Virulence of silver-resistant mutant of Klebsiella pneumoniae in burn wound model. 145 94

Oxaloacetate decarboxylase of Klebsiella pneumoniae was shown to contain between 0.6 and 1.0 mol zinc per mol enzyme in different preparations. The decarboxylase activity was completely abolished after 15 min incubation with 1 mM Hg(NO3)2 in phosphate buffer, while the activity decreased only 20% if the incubation was performed in MES/Tris buffer. Treatment of the isolated subunits with Hg(NO3)2 indicated that the binding site for Hg2+ ions is on the alpha subunit. Other inhibitors of the decarboxylase are KSCN and diethylstilbestrol. Inactivation of the enzyme with 2% 1-butanol was significantly reduced by 100 mM NaCl. Sodium ions also protected the isolated beta + gamma subunits from a digestion with trypsin.
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PMID:The sodium ion pumping oxaloacetate decarboxylase of Klebsiella pneumoniae. Metal ion content, inhibitors and proteolytic degradation studies. 154 90

Bismuth subsalicylate (BSS), sodium salicylate, and bismuth nitrate were compared with respect to their effects on capsular polysaccharide (CPS) production, bacterial growth inhibition, and potentiation of aminoglycoside inhibition on strains of Gram-negative bacteria. At 250 microM, BSS reduced CPS production in Klebsiella pneumoniae cultures by greater than 90% in contrast to a 36% reduction by salicylate. At 500 microM, salicylate reduced CPS by 52%, versus a 70% reduction by bismuth nitrate. Substantial reduction of CPS production by BSS occurred before bacterial growth inhibition was observed. However, BSS at 250 microM decreased cell viability by 21%, and at 1 mM by 50%. Bismuth nitrate was equally inhibitory to cell growth. Salicylate at 1 mM did not affect bacterial cell counts. The susceptibility of selected Gram-negative bacteria to aminoglycoside antibiotics was studied in the presence of BSS or salicylate. Generally, salicylate at 2.5 mM reduced the concentration of aminoglycoside required to inhibit culture growth for 24 h (IC24) by two-fold. In contrast, 700 microM BSS reduced the IC24 for amikacin four-fold for a resistant K. pneumoniae strain. At 500 microM, BSS reduced the IC24 of gentamicin seven-fold for Salmonella typhimurium. Inhibitory concentrations of amikacin or tobramycin for Enterobacter cloacae or Serratia marcescens were also reduced seven-fold with 500 microM BSS. Bismuth nitrate reduced the IC24 of tobramycin by four-fold for E. cloacae. Thus, the profound effects of BSS on CPS production and aminoglycoside potentiation were due to the additive effects of bismuth and salicylate ions, whilst its effects on growth inhibition were due to the bismuth ion.
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PMID:Reduction of capsular polysaccharide and potentiation of aminoglycoside inhibition in gram-negative bacteria by bismuth subsalicylate. 181 78

In 1985 the vernacular name Enteric Group 90 was coined for a small group of strains that had been referred to our laboratory as probable strains of Salmonella but did not agglutinate in Salmonella typing antisera. By DNA-DNA hybridization (hydroxyapatite method, 32P), seven strains of Enteric Group 90 were found to be closely related (98 to 100% at 60 degrees C and 94 to 100% at 75 degrees C) to the first strain received (0370-85). The relatedness of Enteric Group 90 to 62 strains of other species of the family Enterobacteriaceae was only 6 to 41%, with the highest values obtained with strains of Salmonella, Kluyvera, Shigella, Klebsiella, Enterobacter, and Citrobacter. We propose a new genus, Trabulsiella, with a single new species, Trabulsiella guamensis, for the highly related group of eight strains formerly known as Enteric Group 90. The type strain is designated ATCC 49490 (CDC 0370-85). T. guamensis strains grew well at 36 degrees C and had positive reactions in the following tests: methyl red, citrate utilization (Simmons) (38% positive at day 1, 88% positive at 2 days), H2S production, lysine decarboxylase, arginine dihydrolase (50% positive at 2 days, 100% positive at 7 days), ornithine decarboxylase, motility, growth in KCN medium, mucate fermentation, acetate utilization, nitrate reduction to nitrite, weak tyrosine hydrolysis (88% positive at 2 days, 100% positive at 7 days), and ONPG (o-nitrophenyl-beta-D-galactopyranoside) test. The strains fermented D-glucose with gas production and fermented L-arabinose, cellobiose, D-galactose, D-galacturonate, maltose, D-mannitol, D-mannose, L-rhamnose, D-sorbitol, trehalose, and D-xylose. T. guamensis strains had negative reactions in the following tests: indole production (13% positive), Voges-Proskauer, urea hydrolysis, phenylalanine deaminase, malonate utilization, lipase (corn oil), DNase, oxidase, pigment production, and acid production from adonitol, D-arabitol, dulcitol, erythritol, myo-inositol, melibiose, alpha-methyl-D-glucoside, raffinose, and sucrose. There were delayed positive reactions for gelatin liquefaction (22 degrees C), which was positive at 12 to 23 days, esculin hydrolysis (13% positive at day 1, 50% positive at 7 days), lactose fermentation (13% positive at 3 to 7 days, 100% positive at 8 to 10 days), glycerol fermentation (88% positive at 7 days), and salicin fermentation (13% positive at day 1, 88% positive at 7 days). All strains were susceptible by the disk diffusion method to colistin, nalidixic acid, gentamicin, streptomycin, kanamycin, chloramphenicol, and trimethoprim-sulfamethoxazole, and most strains were susceptible to sulfadiazine (75% susceptible), tetracycline (88%), and carbenicillin (75%). The strains were resistant to penicillin, cephalothin, and ampicillin. The strains were isolated from vacuum cleaner dust (five strains), soil (one strain), and human feces (two strains). Although T. guamensis can occur in human diarrheal stools, there is no evidence that it actually causes diarrhea. Its main interest to clinical microbiologists may be its possible misidentification as a strain Salmonella.
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PMID:Trabulsiella guamensis, a new genus and species of the family Enterobacteriaceae that resembles Salmonella subgroups 4 and 5. 188 44


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