Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At growth temperatures above 37 degrees C, Klebsiella pneumoniae does not grow in a medium containing N2 or NO3- as nitrogen sources. However, both the growth in the presence of other nitrogen sources as well as the in vitro nitrogenase activity are not affected at this temperature. The inability to fix N2 at high temperature is due to the failure of the cells to synthesize nitrogenase and other nitrogen fixation (nif) gene encoded proteins. When cells grown under nitrogen fixing conditions at 30 degrees C were shifted to 39 degrees C, there was a rapid decrease of the rate of de novo biosynthesis of nitrogenase (component 1), nitrogenase reductase (component 2), and the nifJ gene product. There was no degradation of nitrogenase at the elevated temperature since preformed enzyme remained stable over a period of at least 3 h at 39 degrees C. Thus, temperature seems to represent a third control system, besides NH4+ and O2, governing the expression of nif genes of K. pneumoniae.
 ...
PMID:Temperature control of nitrogen fixation in Klebsiella pneumoniae. 39 99

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.
 ...
PMID:The sodium ion pumping oxaloacetate decarboxylase of Klebsiella pneumoniae. Metal ion content, inhibitors and proteolytic degradation studies. 154 90

Nalidixic and five newer 4-quinolones, ciprofloxacin, enoxacin, norfloxacin, ofloxacin and pefloxacin were tested against 576 recent clinical aerobic bacterial isolates. The 4-quinolones were regularly active (MIC90 less than 4 mg/l) against the following bacteria: Staphylococcus aureus, S. epidermidis, S. saprophyticus, different Enterobacteriaceae, Haemophilus influenzae, Campylobacter jejuni, Pseudomonas aeruginosa, Agrobacter spp., Aeromonas spp., Plesiomonas spp., Neisseria meningitidis. Other bacteria were usually intermediately susceptible or resistant: different streptococci, Listeria monocytogenes, Nocardia asteroides, P. maltophilia, Achromobacter xylosoxydans and Alcaligenes denitrificans. Ciprofloxacin was the most potent compound, followed by ofloxacin and pefloxacin, norfloxacin and enoxacin being less active. All the 4-quinolones were much more active than nalidixic acid. The MBC/MIC ratios of the 4-quinolones were between 1 and 2 with a majority of strains, and between 2 and 3 with Streptococcus agalactiae, Str. faecalis and L. monocytogenes. A two- to eight-fold increase of MIC was observed by increasing the inoculum 10,000-fold with most of the strains tested. Susceptible bacterial population of Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens and P. aeruginosa contained more clones resistant to nalidixic acid (10(4) to 10(8) at four times the MIC) than to 4-quinolones (10(5) to 10(9) at four times the MIC). Supplementing the media with MgSO4 produced smaller inhibition zone diameters with a disc diffusion method than those obtained with non-supplemented agar, with all quinolone or strains. Less regular effect, or no effect was obtained after supplementation with ZnSO4 or Ca(NO3)2.
 ...
PMID:In-vitro activity of newer quinolones against aerobic bacteria. 294 Feb 14

Oxygen caused a reversible inhibition (switch-off) of nitrogenase activity in whole cells of four strains of diazotrophs, the facultative anaerobe Klebsiella pneumoniae and three strains of photosynthetic bacteria (Rhodopseudomonas sphaeroides f. sp. denitrificans and Rhodopseudomonas capsulata strains AD2 and BK5). In K. pneumoniae 50% inhibition of acetylene reduction was attained at an O2 concentration of 0.37 microM. Cyanide (90 microM), which did not affect acetylene reduction but inhibited whole-cell respiration by 60 to 70%, shifted the O2 concentration that caused 50% inhibition of nitrogenase activity to 2.9 microM. A mutant strain of K. pneumoniae, strain AH11, has a respiration rate that is 65 to 75% higher than that of the wild type, but its nitrogenase activity is similar to wild-type activity. Acetylene reduction by whole cells of this mutant was inhibited 50% by 0.20 microM O2. Inhibition by CN- of 40 to 50% of the O2 uptake in the mutant shifted the O2 concentration that caused 50% inhibition of nitrogenase to 1.58 microM. Thus, when the respiration rates were lower, higher oxygen concentrations were required to inhibit nitrogenase. Reversible inhibition of nitrogenase activity in vivo was caused under anaerobic conditions by other electron acceptors. Addition of 2 mM sulfite to cell suspensions of R. capsulata B10 and R. sphaeroides inhibited nitrogenase activity. Nitrite also inhibited acetylene reduction in whole cells of the photodenitrifier R. sphaeroides but not in R. capsulata B10, which is not capable of enzymatic reduction of NO2-. Lower concentrations of NO2- were required to inhibit the activity in NO3- -grown cells, which have higher activities of nitrite reductase.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Mechanism of nitrogenase switch-off by oxygen. 354 74

We have shown that the low histidase activity found in anaerobic, nitrogen-limited cultures of Klebsiella pneumoniae is due to repression of the right-hand hut operon. In addition, we have examined the effects of NO3- on the aerobic and anaerobic expression of catabolite- and NH4+-repressible enzymes in this organism. NO3- permitted anaerobic growth of K. pneumoniae in minimal medium containing histidine as the sole carbon source, and histidase and succinate dehydrogenase were derepressed during anaerobic growth in histidine/NO3- medium. Use of sucrose rather than histidine as the carbon source reversed the effects of NO3- and repressed histidase and succinate dehydrogenase activities. Anaerobic growth in sucrose/NO3- medium also uncoupled the expression of urease and glutamine synthetase.
 ...
PMID:Effects of anaerobiosis and nitrate on the expression of succinate dehydrogenase and enzymes associated with nitrogen metabolism in Klebsiella pneumoniae. 612 18

The rate of biosynthesis of nitrogenase polypeptides in Klebsiella pneumoniae was determined in a medium containing NaNO3 or NaNO2. Nitrogenase biosynthesis was completely repressed by NO3- in a mutant strain, strain SK-25, that is derepressed for nitrogenase biosynthesis in the presence of NH4+. Chlorate-resistant mutants, derived from strain SK-25, that are defective in NO3- respiration produced nitrogenase in the presence of NO3-. Strain SK-56), a chlorate-resistant derivative capable of NO3- respiration, produced no nitrogenase in the presence of NO3- or NO2-. Klebsiella pneumoniae respired under anaerobic conditions utilizing either NO3- or NO2- as terminal electron acceptor. A mechanism for the control of nitrogenase biosynthesis is discussed involving the redox control of anaerobic enzyme systems.
 ...
PMID:Regulation of nitrogenase biosynthesis in Klebsiella pneumoniae: effect of nitrate. 699 23

A bacterial strain F-5-2, isolated from soil and identified as Klebsiella pneumoniae, removed NH4+ completely in 24 h of aerobic cultivation in a medium containing 1 mg/ml of NH4NO3. However, 70% of the NO3- originally provided remained. When 100 microM Fe2+ was added to the medium, both NH4+ and NO3- were removed simultaneously and completely from the culture within 6 h of incubation. In addition, the amount of MoO4- in the medium markedly affected the bacterial cell growth and utilization of NH4+ and NO3-. The bacterium could remove 4 mg/ml of NH4NO3 completely in 48 h of aerobic cultivation in a medium containing 100 microM Fe2+ and 0.8 pM MoO4(2-). The total nitrogen in the culture containing its cells was decreased to 14% of that in the NH4NO3 originally provided. GC-MS analysis demonstrated that N2 was generated from the nitrogen atoms of both NH4+ and NO3-.
 ...
PMID:Isolation and culture conditions of a Klebsiella pneumoniae strain that can utilize ammonium and nitrate ions simultaneously with controlled iron and molybdate ion concentrations. 1209 51

2-(2-Pyridinyl)- (LI), 2-(6-methyl-2-pyridinyl)- (LII), 2-(6-methyl-2-pyridinyl)-5-methyl-(LIII), 2-(3-pyridinyl)- (LIV), 2-(3-pyridinyl)-5-methyl-1H-benzimidazoles (LV) and their complexes with Fe(NO3)3, Cu(NO3)2, Zn(NO3)2, and AgNO3 were synthesized and antibacterial activity of the compounds was tested toward Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Proteus mirabilis and antifungal activity against Candida albicans. The methyl groups of LIII increase the antimicrobial activity. The AgI complexes have considerable activity toward the microorganisms. Some ZnII complexes show an antimicrobial effect against S. aureus and S. flexneri, although the ligands themselves have no effect. CuII complexes have a considerable antibacterial effect to S. aureus and S. epidermidis.
 ...
PMID:Antimicrobial activity of some 2- and 3-pyridinyl-1H-benzimidazoles and their FeIII, CuII, ZnII, and AgI complexes. 1453 78

The two ammonia-assimilating enzymes glutamate dehydrogenase (GDH; EC 1.4.1.4) and glutamine synthetase (GS; EC 6.3.1.2) were synthesized steadily during the cell growth of Klebsiella pneumoniae F-5-2 that can utilize NH4+ and NO3- simultaneously under aerobic conditions. The enzymes were purified to homogeneity from cell extracts and characterized. The molecular mass of the purified GDH was 300 kDa with six identical 52-kDa subunits. GDH showed its maximal activity (aminating) at pH 8.0 and was stable between pHs 5.5 and 11.5. The enzyme was NADP-specific and strongly inhibited by Ag+. It catalyzed the amination of 2-ketovalerate, 2-ketoadipate, and 2-ketobutyrate, in addition to 2-ketoglutarate. The purified GS has a molecular mass of 470 kDa with eight identical 60-kDa subunits. GS showed its maximal activity at pH 8.0 and was stable between pHs 6.0 and 7.0. The enzyme was strongly inhibited by Fe3+, Hg2+, and Cu2+.
 ...
PMID:Ammonia assimilation in Klebsiella pneumoniae F-5-2 that can utilize ammonium and nitrate ions simultaneously: purification and characterization of glutamate dehydrogenase and glutamine synthetase. 1623 53

Six biocides resistant isolates were isolated from dental unit water lines (DUWL) in Pakistan. All isolates could tolerate 150 microg ml(-1 )of biocides (5.25% sodium hypocholrite, 35% H2O2, 4% tween 20, 1% povidine iodine, 0.2% chlorohexidine gluconate, 1% ethylene di-amino tetra acetic acid and 1% phenol) on l-agar and 100 microg ml(-1 )in l-broth. The growth rate of all isolates was determined by generating growth curves at 37 degrees C for 48 h. The isolates were found to differ in growth rates with lag phase varying from (4-6 h) in biocides supplemented media compared to 2-4 h in biocides free medium. They have wide temperatures (24-42 degrees C) and pH (5-9) ranges. Traditional ways of identification of bacteria by phenotypic characteristics were accomplished by phenotypic and biochemical characterization. Heavy metals and antimicrobial susceptibility tests indicated that all isolates examined were resistant to trimethoprim, chloramphenicol while sensitive to HgCl2 and Pb (NO3)2. Almost all isolates were opportunistic pathogens. The 16S rRNA-encoding genes from these six isolates were sequenced to confirm the identity of these isolates. 5 different genera (Bacillus, Achromobacter, Pseudomonas and Klebsiella) of bacteria were identified by 16S rDNA genes amplified from genomic DNA of biocides resistant DUWL biofilm isolates. Analysis of 16S rDNA genes revealed a much more clear identification of microorganisms than culture methods. However, different species of the same genera can have the same 16S rRNA gene sequence but are different due to phenotypic differences or different clinical manifestations.
 ...
PMID:Isolation and characterization of biocides resistant bacteria from dental unit water line biofilms. 1921 3


1 2 Next >>