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

Using the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) as a polyclonal B-cell activator (PBA) and sheep red blood cells (SRBC) as a T cell-dependent antigen, we compared the ability of PBA and antigen to differentiate (generate antibody-forming cells, AFC) and proliferate (generate immunological memory) virgin B cells and B memory cells. In vitro CPS-K induced the differentiation of IgM virgin B cells, IgM B memory cells and IgG B memory cells to AFC, as well as or better than SRBC. The differentiation of B memory cells to AFC by CPS-K did not require the participation of macrophages or T cells, whereas the action of SRBC depended strictly upon the helper actions of these cells. The responsiveness to CPS-K and SRBC of normal and antigen-primed spleen cells as judged by anti-SRBC PFC responses in vitro was markedly decreased after stimulation of virgin B cells and B memory cells in vivo by CPS-K injection into normal or primed mice but greatly increased after the injection of SRBC. The decrease in the responsiveness to CPS-K of spleen cells from mice treated with CPS-K appeared principally due to exhaustion of the functions of B cells and B memory cells. From the present data it has been concluded that the signals required for the differentiation and proliferation of B cells of B memory cells are different from each other, the signal for differentiation being provided by either antigen (SRBC) or PBA (CPS-K), while the signal for proliferation only by antigen.
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PMID:Comparative studies on the actions of antigen and polyclonal B-cell activator in differentiation and proliferation of B-cells and B memory cells. 78 31

When grown anaerobically on L-rhamnose, Salmonella typhimurium excreted 1,2-propanediol as a fermentation product. Upon exhaustion of the methyl pentose, 1,2-propanediol was recaptured and further metabolized, provided the culture was kept under anaerobic conditions. n-Propanol and propionate were found in the medium as end products of this process at concentrations one-half that of 1,2-propanediol. As in Klebsiella pneumoniae (T. Toraya, S. Honda, and S. Fukui, J. Bacteriol. 139:39-47, 1979), a diol dehydratase which transforms 1,2-propanediol to propionaldehyde and the enzymes involved in a dismutation that converts propionaldehyde to n-propanol and propionate were induced in S. typhimurium cultures able to transform 1,2-propanediol anaerobically.
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PMID:Anaerobic metabolism of the L-rhamnose fermentation product 1,2-propanediol in Salmonella typhimurium. 328 5

A parallel study has been made of the variation of the ATP pool and the specific power of cells of Klebsiella aerogenes during aerobic growth in glucose-limited medium under carefully defined conditions of growth and test. During the early part of exponential growth there was a marked increase in both the ATP pool and the specific power to near constant values during the later stages of growth; oscillations about the mean values were observed for each parameter. With the exhaustion of glucose and the cessation of growth both and ATP pool and the specific power decreased rapidly, the ATP pool to a low constant value and the specific power to zero. Changes in the values of these parameters during growth are discussed and it is concluded that the specific power is more dependent on the rate of catabolism rather than on the degree of coupling while the opposite is true for the ATP pool. Both parameters are, however, indicators of similar metabolic processes.
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PMID:Microcalorimetry studies of energy changes during the growth of Klebsiella aerogenes in simple salts/glucose media; correlation of specific power and size of the ATP pool. 390 40

The power-time traces for cells of Klebsiella aerogenes grown in phosphate-limited media were unlike those for cells grown in phosphate-sufficient media. At a phosphate concentration of 18 mumol dm-3 three phases of growth were recognized: the exponential growth phase during which phosphate became exhausted; a slower growth phase to the exhaustion of glucose, and a period of minimal growth when acetate, formed as secondary metabolite, was metabolized. At a concentration of 40 mumol dm-3 only two phases were identified. From the measured values of biomass, carbon dioxide output, glucose and acetate, mass and energy balances were established for each phase of growth and for overall growth. The results are discussed in terms of the energy stored as biomass, that wasted as heat and that required for maintenance and biosynthetic processes when the cells are grown under normal and stressful conditions.
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PMID:Microcalorimetry studies of energy changes during the growth of Klebsiella aerogenes in simple salts/glucose media: growth in phosphate-limited medium. 391 45

The utilization of glycerol as a carbon source for growth by Klebsiella aerogenes, strain 2103, involves separate aerobic (sn-glycerol-3-phosphate or G3P) and anaerobic (dihydroxyacetone or DHA) pathways of catabolism. Enzyme and transport activities of the aerobic pathway are elevated in cells grown under oxygenated conditions on glycerol or G3P. Anaerobic growth on G3P as carbon source requires the presence of an exogenous hydrogen acceptor such as fumarate; cells thus grown also are highly induced in the G3P pathway. Anaerobic growth on glycerol requires no exogenous hydrogen acceptors; cells thus grown are highly induced in the DHA pathway but almost uninduced in the G3P pathway and the addition of fumarate electron acceptors has no effect on the relative levels of the two pathways. When both glycerol and G3P are provided anaerobically with fumarate, the DHA pathway is still preferentially induced, which probably accounts for the exclusive utilization of glycerol until its exhaustion. These observations suggest the presence of a regulatory control of G3P pathway imposed by the operation of the DHA pathway.
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PMID:Regulation of glycerol catabolism in Klebsiella aerogenes. 436 50

The addition of an oxidizable substrate to a continuous culture of Klebsiella aerogenes is known to cause an increased respiration rate that decreases in discrete steps as the added substrate is being exhausted. We have used a simple new technique to show that this phenomenon is also produced by washed, resting cells harvested from batch or continuous growth culture. The stepwise-decreasing respiration rate is caused by the exhaustion of different pools of intermediates. Each plateau of respiration rate is a measure of the activity of one or more enzymes that are rate limiting in the exhaustion of pools of intermediates. If the identities of the enzymes that are rate limiting at the different plateaux are known, the method may allow the determination, in one experiment, of the activities of up to six different enzymes in the intact bacteria. Integration of the respiration-rate measurements yields the total amount of O(2) taken up. After the addition of glucose to the washed resting bacteria 37% of the amount of O(2) required for the complete oxidation of the glucose was taken up. Acetate, pyruvate and succinate were all oxidized to the extent of 51%.
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PMID:The occurrence of a stepwise-decreasing respiration rate during oxidative assimilation of different substrates by resting Klebsiella aerogenes in a system open to oxygen. 478 31

A new selection procedure has been developed for isolating prototrophic relaxed mutants of Klebsiella pneumoniae. Two mutants were isolated. One of them showed a fully relaxed phenotype, while the other one behaved in a semi-relaxed way. The wild-type strain, as well as the rel mutants exerted similar patterns to their E. coli counterparts in RNA, protein, ppGpp and pppGpp accumulation during amino starvation, carbon source shift-down and nitrogen starvation. Both mutants became stringent after introducing an F'-factor carrying the relA+ allele from Escherichia coli. The relaxed phenotype could be recovered by curing the F'-factor. Some of the pleiotropic consequences of rel mutations found in E. coli are present in the Klebsiella mutants also while some of them are absent. The mutants are defective in dinitrogen fixation after the exhaustion of limiting ammonium from the culture medium. However, their merodiploid derivatives, carrying the E. coli relA+ allele, showed the wild-type level of nitrogenase activity under the same conditions.
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PMID:Isolation and characterization of prototrophic relaxed mutants of Klebsiella pneumoniae. 626 22

When strain C3 of Klebsiella pneumoniae is grown on a minimal medium with excess glucose, isocitrate dehydrogenase, malate dehydrogenase, and succinate dehydrogenase specific activities increase in the last period of the exponential growth phase and in the beginning of the stationary phase. Glucose exhaustion does not alter the development of malate dehydrogenase and succinate dehydrogenase, but specific activities are higher than those obtained with excess glucose. In contrast, glucose exhaustion can be correlated with a decrease of isocitrate dehydrogenase specific activity in the stationary phase. Induction of strain C3 isocitrate dehydrogenase by glucose in complex medium and repression by cAMP in mineral medium were observed. Glucose induction and the NADP/NADPH ratio are suggested as regulatory mechanisms controlling isocitrate dehydrogenase synthesis in the Enterobacteriaceae, but the former appears to be restricted to some Klebsiella strains.
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PMID:Effect of the carbon source and cyclic AMP on isocitrate dehydrogenase, succinate dehydrogenase, and malate dehydrogenase in Klebsiella pneumoniae C3. 629 82

The kinetics of derepression of the enzyme nitrogenase were investigated, after exhaustion of a limiting amount of ammonium from the culture medium, in a prototrophic stringent-relaxed pair of Klebsiella pneumoniae strains and in their F relA+-F relA derivatives. The results indicate that ppGpp (guanosine 3'-5' diphosphate) increases the nitrogen fixation capability of K. pneumoniae by at least three different mechanisms. (1) It prevents exhaustion of the ATP pool when nitrogen starvation is imposed. (2) The translational defects in relaxed mutants are suppressed by ppGpp during nif derepression. (3) The synthesis of nitrogenase components is at least five times higher in the presence of ppGpp than in its absence. This latter conclusion was based on experimental results obtained when following the incorporation of (35S)-methionine into nitrogenase components after pulse labelling at various time intervals during nif derepression. The nitrogenase components were separated by solid phase radioimmunoassay as well as by two-dimensional gel electrophoresis.
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PMID:Positive involvement of ppGpp in derepression of the nif operon in Klebsiella pneumoniae. 704 80

Exopolysaccharide (EPS) was produced by Klebsiella pneumoniae K63 grown in fed-batch cultures using different procedures of the supply of carbon or nitrogen (N) source, or both. Cultures grown with excess of glucose and limitation or exhaustion of N produced 54.8 and 47.4 g(EPS) l(-1), respectively. These cultures also led to an accumulation of 'overflow' metabolites representing more than 16% of carbon conversion. The consistency indexes ( K ) obtained to the end of the cultures, characteristic of the rheological property of the biopolymer, were 16.4 Pa s(n) for N deficiency and 5.2 Pa s(n) for N limitation conditions. The simultaneous limitation of glucose and N decreased the excretion of co-metabolites (6.4% of carbon conversion) and the EPS production (18.1 g(EPS) l(-1)), while improving the quality of the polysaccharide, characterized by the highest K of 126.2 Pa s(n) and the highest pseudoplasticity degree (flow behaviour index, n=0.2).
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PMID:Improved process for exopolysaccharide production by Klebsiella pneumoniae sp. pneumoniae by a fed-batch strategy. 1548 91


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