Glycerol kinase as a substitute for dihydroxyacetone kinase in a mutant of Klebsiella pneumoniae

1982 ◽  
Vol 152 (3) ◽  
pp. 1303-1307
Author(s):  
R Z Jin ◽  
R G Forage ◽  
E C Lin
Keyword(s):  
Energy Source ◽  
Growth Rate ◽  
Klebsiella Pneumoniae ◽  
Sole Source ◽  
Glycerol Kinase ◽  
Aerobic Growth ◽  
Dihydroxyacetone Kinase ◽  
Rate Limiting

With dihydroxyacetone as the sole source of carbon and energy, constitutively synthesized glycerol kinase of the glp system supported aerobic growth of Klebsiella pneumoniae mutants lacking the inducible dihydroxyacetone kinase of the dha system. Glycerol kinase had an apparent Km of 0.01 mM for its physiological substrate and 1 mM for its surrogate substrate. However, the growth rate on dihydroxyacetone of cells relying on glycerol kinase increased with the concentration of the carbon and energy source up to 50 mM, suggesting that permeation is rate limiting.

scholarly journals Complex Regulation of Urease Formation from the Two Promoters of the ure Operon of Klebsiella pneumoniae

2007 ◽  
Vol 189 (21) ◽  
pp. 7593-7599 ◽  
Author(s):  
Qiong Liu ◽  
Robert A. Bender
Keyword(s):  
Growth Rate ◽  
Klebsiella Pneumoniae ◽  
Specific Activity ◽  
Regulatory System ◽  
Fold Increase ◽  
Sole Source ◽  
Proximal Promoter ◽  
Absolute Requirement ◽  
Activity Difference ◽  
Operon Expression

ABSTRACT Klebsiella pneumoniae can use urea as the sole source of nitrogen, thanks to a urease encoded by the ureDABCEFG operon. Expression of this operon is independent of urea and is regulated by the supply of nitrogen in the growth medium. When cells were growth rate limited for nitrogen, the specific activity of urease was about 70 times higher than that in cells grown under conditions of excess nitrogen. Much of this nitrogen regulation of urease formation depended on the nitrogen regulatory system acting through the nitrogen assimilation control protein, NAC. In a strain deleted for the nac gene, nitrogen limitation resulted in only a 7-fold increase in the specific activity of urease, in contrast to the 70-fold increase seen in that of the wild type. The ure operon was transcribed from two promoters. The proximal promoter (P1) had an absolute requirement for NAC; little or no transcription was seen in the absence of NAC. The distal promoter (P2) was independent of NAC, but its activity increased about threefold when the growth rate of the cells was limited by the nitrogen source. Transcriptional regulation of P1 and P2 accounted for most of the changes in urease activity seen under various nitrogen conditions. However, when transcription of ureDABCEFG was less than 20% of its maximum, the amount of active urease formed per transcript of ure decreased almost linearly with decreasing transcription. This may reflect a defect in the assembly of active urease and accounted for as much as a threefold activity difference under the conditions tested here. Thus, the ure operon was transcribed from a NAC-independent promoter (P2) and the most strongly NAC-dependent promoter known (P1). Most of the regulation of urease formation was transcriptional, but when ure transcription was low, assembly of active urease also was defective.

Oscillating conditions for influencing the composition of mixed biological cultures

1998 ◽  
Vol 37 (4-5) ◽  
pp. 259-262 ◽  
Author(s):  
Bjarne R. Horntvedt ◽  
Morten Rambekk ◽  
Rune Bakke
Keyword(s):  
Growth Rate ◽  
Specific Growth ◽  
Heterotrophic Bacteria ◽  
Bacterial Species ◽  
Rate Reduction ◽  
Similar Strategy ◽  
Sinusoidal Oscillations ◽  
Specific Growth Rates ◽  
Rate Limiting ◽  
Concentration Levels

This paper presents a strategy in which mixed biological cultures are exposed to oscillating concentration levels, to improve the potential for coexistence of desired bacterial species. A mechanistic mathematical model is constructed to investigate and illustrate this strategy. This paper is focused on competition between nitrifying, denitrifying and aerobic heterotrophic bacteria in a CSTR with sludge recycle. For nitrifying and aerobic heterotrophic cultures, the effect of sinusoidal oscillations in DO levels with an amplitude of 1.0 mg/l is a 16% specific growth rate reduction compared to that at a constant DO level. The denitrifiers growth rate is increased by an average of 59%, compared to the constant DO level situation. A similar strategy has been tested in a pilot plant. It is concluded that the influence on specific growth rates is a function of the amplitude of the oscillations. The effects are greatest when concentrations fluctuate around the half saturation concentration of the rate limiting component(s).

scholarly journals Coupling among growth rate response, metabolic cycle, and cell division cycle in yeast

2011 ◽  
Vol 22 (12) ◽  
pp. 1997-2009 ◽  
Author(s):  
Nikolai Slavov ◽  
David Botstein
Keyword(s):  
Growth Rate ◽  
Oxygen Consumption ◽  
Cell Division ◽  
Carbon Source ◽  
Oxidative Metabolism ◽  
Sole Source ◽  
Cell Division Cycle ◽  
Steady State Responses ◽  
Yeast Metabolic Cycle ◽  
Metabolic Cycle

We studied the steady-state responses to changes in growth rate of yeast when ethanol is the sole source of carbon and energy. Analysis of these data, together with data from studies where glucose was the carbon source, allowed us to distinguish a “universal” growth rate response (GRR) common to all media studied from a GRR specific to the carbon source. Genes with positive universal GRR include ribosomal, translation, and mitochondrial genes, and those with negative GRR include autophagy, vacuolar, and stress response genes. The carbon source–specific GRR genes control mitochondrial function, peroxisomes, and synthesis of vitamins and cofactors, suggesting this response may reflect the intensity of oxidative metabolism. All genes with universal GRR, which comprise 25% of the genome, are expressed periodically in the yeast metabolic cycle (YMC). We propose that the universal GRR may be accounted for by changes in the relative durations of the YMC phases. This idea is supported by oxygen consumption data from metabolically synchronized cultures with doubling times ranging from 5 to 14 h. We found that the high oxygen consumption phase of the YMC can coincide exactly with the S phase of the cell division cycle, suggesting that oxidative metabolism and DNA replication are not incompatible.

Growth rate limiting mechanisms of YBa2Cu3O7 films manufactured by ex situ processing

2001 ◽  
Vol 353 (1-2) ◽  
pp. 14-22 ◽  
Author(s):  
Vyacheslav F. Solovyov ◽  
Harold J. Wiesmann ◽  
Masaki Suenaga
Keyword(s):  
Growth Rate ◽  
Ex Situ ◽  
Rate Limiting

scholarly journals Glutathione Reductase from Lactobacillus sanfranciscensis DSM20451T: Contribution to Oxygen Tolerance and Thiol Exchange Reactions in Wheat Sourdoughs

2007 ◽  
Vol 73 (14) ◽  
pp. 4469-4476 ◽  
Author(s):  
André Jänsch ◽  
Maher Korakli ◽  
Rudi F. Vogel ◽  
Michael G. Gänzle
Keyword(s):  
Growth Rate ◽  
Glutathione Reductase ◽  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Exchange Reactions ◽  
Aerobic Growth ◽  
Oxygen Tolerance ◽  
Lactobacillus Sanfranciscensis

ABSTRACT The effect of the glutathione reductase (GshR) activity of Lactobacillus sanfranciscensis DSM20451T on the thiol levels in fermented sourdoughs was determined, and the oxygen tolerance of the strain was also determined. The gshR gene coding for a putative GshR was sequenced and inactivated by single-crossover integration to yield strain L. sanfranciscensis DSM20451TΔgshR. The gene disruption was verified by sequencing the truncated gshR and surrounding regions on the chromosome. The gshR activity of L. sanfranciscensis DSM20451TΔgshR was strongly reduced compared to that of the wild-type strain, demonstrating that gshR indeed encodes an active GshR enzyme. The thiol levels in wheat doughs fermented with L. sanfranciscensis DSM20451 increased from 9 μM to 10.5 μM sulfhydryl/g of dough during a 24-h sourdough fermentation, but in sourdoughs fermented with L. sanfranciscensis DSM20451TΔgshR and in chemically acidified doughs, the thiol levels decreased to 6.5 to 6.8 μM sulfhydryl/g of dough. Remarkably, the GshR-negative strains Lactobacillus pontis LTH2587 and Lactobacillus reuteri BR11 exerted effects on thiol levels in dough comparable to those of L. sanfranciscensis. In addition to the effect on thiol levels in sourdough, the loss of GshR activity in L. sanfranciscensis DSM20451TΔgshR resulted in a loss of oxygen tolerance. The gshR mutant strain exhibited a strongly decreased aerobic growth rate on modified MRS medium compared to either the growth rate under anaerobic conditions or that of the wild-type strain, and aerobic growth was restored by the addition of cysteine. Moreover, the gshR mutant strain was more sensitive to the superoxide-generating agent paraquat.

scholarly journals Hydrocarbon-Degrading Bacterial Strain Pseudomonas mendocina Newly Isolated from Marine Sediments and Seawater of Oran Harbor (Algerian Coast)

2020 ◽  
Vol 2 (2) ◽  
pp. 22-29
Author(s):  
Bendadeche Medjahed Faiza
Keyword(s):  
Energy Source ◽  
Growth Rate ◽  
Crude Oil ◽  
16S Rdna ◽  
Marine Sediments ◽  
Growth Kinetic ◽  
Culture Conditions ◽  
Pseudomonas Mendocina ◽  
Degrading Bacterium ◽  
Nacl Concentration

Contamination by petroleum hydrocarbons causes serious dangers to human health and the environment, whether by accidental or chronic contamination. Due to the large flow of ships, the commercial harbor of Oran is subject to pollution particularly by polycyclic aromatic hydrocarbons. For that, bioremediation by indigenous microorganisms is the most important method to eliminate or decrease this contamination. In the present paper, hydrocarbon-degrading bacterium strain SP57N has been studied, newly isolated from contaminated marine sediments and sea water from the harbor of Oran (Northwestern-Algeria), using of Bushnell-Hass salt medium (BHSM). The strain SP57N was Gram-negative, oxidase negative, catalase negative, motile, Rod-shaped bacteria, identified molecularly as Pseudomonas mendocina based on partial 16S rDNA gene sequence analysis, using the BLAST program on National Centre for Biotechnology Information (NCBI) and the EzBioCloud 16S rDNA databases. This isolate could growth on high concentrations of crude oil (up to 10 %, v/v). The effects of some culture conditions such as temperature, NaCl concentration and pH on growth rate of strain SP57N on crude oil as the sole carbon and energy source were studied. In addition, growth kinetic of this isolate on crude oil during 20 days of culture at 140 rpm, under optimal culture conditions was considered. The results showed maximum growth rate at temperature 25°C, 3% (w/v) of NaCl concentration and pH 7. Results of growth kinetic on crude oil as sole carbon and energy source showed that the stationary phase was attained at day 12. Thus, Pseudomonas mendocina SP57N had effectively hydrocarbon-degrading potential, and could be used as an efficacy degrader to initiate a biological eco-friendly method for the bioremediation of the hydrocarbon pollution on the port of Oran, and marine environment.

scholarly journals Prerequisites for the resumption of the growth rate of hydrogen energy, a review of foreign experience and prospects for development in Russia

2021 ◽  
pp. 131-136
Author(s):  
A. S. Prozorov ◽  
E. O. Kalmykova
Keyword(s):  
Energy Source ◽  
Growth Rate ◽  
Renewable Energy ◽  
Retrospective Analysis ◽  
World Economy ◽  
Renewable Energy Sources ◽  
Energy Sources ◽  
Hydrogen Energy ◽  
Foreign Experience ◽  
The World

At the beginning of the XXI century environmental problems began to have an integrated impact on various regions of our planet. The agenda of major international forums addresses issues related to their solution with the active use of renewable energy sources, including the expansion of the use of hydrogen in various sectors of the world economy. The article provides a brief overview on the prerequisites for the resumption of interest in the use of hydrogen as an energy source, a review of foreign experience in terms of regulatory regulation and incentives, as well as a retrospective analysis of domestic experience in the use of hydrogen and the prospects for the development of hydrogen energy in modern Russian realities. 

Preliminary Design of Wind Turbine Blades for Manufacture Using Local Capabilities

2001 ◽  
Author(s):  
Sarim N. Al-Zubaidy ◽  
Jacqueline Bridge ◽  
Alwyn Johnson
Keyword(s):  
Energy Source ◽  
Growth Rate ◽  
Wind Energy ◽  
Wind Turbine ◽  
Fluid Dynamic ◽  
Turbine Blades ◽  
Design Procedure ◽  
Wind Turbine Blades ◽  
Horizontal Axis Wind Turbine ◽  
Average Deviation

Abstract In the past ten to fifteen years wind energy remerged on the world scene with a very healthy growth rate, it has outstripped photovoltaics (solar cells) as the world’s fastest growing energy source, with a growth rate in excess of 30 percent per annum. No longer just a “nice idea for the future” Wind energy is becoming a mainstream energy source for many countries. The proposed paper will present a procedure (using numerical methods) for the design and analysis of Horizontal Axis Wind Turbine (HAWT) rotors. To ascertain the accuracy and to determine where further improvements could be initiated; numerical findings were then compared with published experimental test data and the compression showed an average deviation of less than 3% and therefore the simplifying assumptions made for the prediction of fluid behavior over an airfoil section was justified. Once the approach was validated and standardised a comprehensive airfoil design was produced. A computational fluid dynamic code coupled with a simple numerical algorithm aided the inverse design procedure. The final design was well proportioned and was theoretically able to meet the stated objective function and satisfied all the imposed constraints (manufacturing and geometrical). The geometrical data was then generated in a form suitable for manufacture using manually and numerically controlled machines.

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