The effects of differing concentrations of CO2 and O2 on the fermentative metabolism of the rumen fungi Neocallimastix patriciarum and Neocallimastix frontalis L2

1998 ◽  
Vol 44 (9) ◽  
pp. 819-824 ◽  
Author(s):  
Elizabeth MR Rees ◽  
David Lloyd ◽  
Alan G Williams
Keyword(s):  
Gas Phase ◽  
Glucose Utilization ◽  
Relative Proportion ◽  
Gas Production ◽  
Ferredoxin Oxidoreductase ◽  
Fermentative Metabolism ◽  
Fungal Isolates ◽  
Neocallimastix Patriciarum ◽  
Neocallimastix Frontalis ◽  
Pyruvate Ferredoxin Oxidoreductase

The effects of decreasing the concentration of CO2 and introducing up to 10% O2 into the headspace gases on the fermentative metabolism of the rumen fungi Neocallimastix patriciarum and Neocallimastix frontalis L2 were investigated. The relative proportion of metabolites produced by both fungi depended on the concentration of CO2 in the headspace. Under lowered CO2 levels, both fungi produced increased acetate, lactate, and H2, whereas the production of ethanol, formate, and (in the case of N. frontalis L2) succinate decreased. Lowered CO2 concentrations also decreased the rate of glucose utilization and cumulative gas production by both fungal isolates. In addition, decreased CO2 levels resulted in decreases in NAD(P)H ferredoxin oxidoreductase and hydrogenase activities, whereas malate dehydrogenase and pyruvate ferredoxin oxidoreductase activities were increased. Both N. patriciarum and N. frontalis L2 required at least 7% CO2 in the gas phase for growth. Both isolates also showed a degree of aerotolerance as they grew when exposed to 5% O2; they also grew in media lacking a reducing agent, providing that O2 was initially <1% of the total headspace concentration.Key words: rumen fungi, Neocallimastix, metabolism, carbon dioxide, oxygen.

scholarly journals Pyruvate-Ferredoxin Oxidoreductase

1971 ◽  
Vol 246 (10) ◽  
pp. 3120-3125
Author(s):  
Kosaku Uyeda ◽  
Jesse C. Rabinowitz
Keyword(s):  
Ferredoxin Oxidoreductase ◽  
Pyruvate Ferredoxin Oxidoreductase

Pyruvate:ferredoxin oxidoreductase in Campylobacter species

1995 ◽  
Vol 41 (2) ◽  
pp. 198-201 ◽  
Author(s):  
James A. Daucher ◽  
Noel R. Krieg
Keyword(s):  
Clostridium Pasteurianum ◽  
Benzyl Viologen ◽  
Minimal Inhibitory Concentrations ◽  
Ferredoxin Oxidoreductase ◽  
Crude Extracts ◽  
Reducing Activity ◽  
Pyruvate Ferredoxin Oxidoreductase ◽  
Pyruvate:Ferredoxin Oxidoreductase ◽  
Campylobacter Species

Twelve strains representing 11 Campylobacter species were tested by two methods to see whether pyruvate:ferredoxin oxidoreductase, which occurs mainly in anaerobes, was also present in these oxygen-respiring microaerophiles. Crude extracts exhibited a pyruvate-dependent reduction of benzyl viologen and, to a lesser extent, metronidazole. Addition of Clostridium pasteurianum ferredoxin enhanced the metronidazole-reducing activity. All strains were inhibited by metronidazole, with minimal inhibitory concentrations ranging from 3 to 25 μg/mL. The results suggest that pyruvate: ferredoxin oxidoreductase is characteristic of the genus.Key words: Campylobacter, microaerophilic, metronidazole, pyruvate.

Aerobic resistance of Trichomonas vaginalis to metronidazole induced in vitro

Parasitology ◽  
1993 ◽  
Vol 106 (1) ◽  
pp. 31-37 ◽  
Author(s):  
J. Tachezy ◽  
J. Kulda ◽  
E. Tomková
Keyword(s):  
Parent Strain ◽  
Trichomonas Vaginalis ◽  
Drug Resistant ◽  
Ferredoxin Oxidoreductase ◽  
Low Concentrations ◽  
Percent Concentration ◽  
Resistant Strains ◽  
Pyruvate Ferredoxin Oxidoreductase

SUMMARYAerobic resistance of Trichomonas vaginalis to metronidazole was induced in vitro by anaerobic cultivation of drug-susceptible trichomonads with low concentrations of the drug (2–3 μg/ml) for 50 days. Minimal lethal concentrations (MLC) for metronidazole of the resistant derivatives were high in aerobic susceptibility assays (MLC = 216–261.5 μg/ml) but low in anaerobic assays (MLC = 4.2–6.3 μg/ml), surpassing MLC values of their parent strain approximately 50-fold and 3-fold under aerobiosis and anaerobiosis, respectively. Sensitivity to metronidazole under anaerobic conditions and activity of the hydrogenosomal enzyme pyruvate: ferredoxin oxidoreductase indicated that the resistance was of the aerobic type. Dependence of the resistance manifestation on O2 was further confirmed by susceptibility assays in vitro performed in defined gas mixtures of different oxygen content (1–20%). Five percent concentration of O2 proved to be the threshold required for resistance demonstration and the MLC values further increased with increasing O2 concentrations. The in vitro-induced resistance was also demonstrated in vivo by subcutaneous mouse assay. The dose of metronidazole needed to cure 50% of infected mice (DC50) was 223 mg/kg × 3 for resistant derivative MR-3a but 6.6 mg/kg × 3 only for its drug-susceptible parent strain. The metronidazole – resistant strains developed in this study correspond by their properties to drug-resistant T. vaginalis strains isolated from patients refractory to treatment, and promise to be a useful tool in the study of 5-nitroimidazole aerobic resistance.

scholarly journals Secondary formation of nitrated phenols: insights from observations during the Uintah Basin Winter Ozone Study (UBWOS) 2014

2015 ◽  
Vol 15 (20) ◽  
pp. 28659-28697 ◽  
Author(s):  
B. Yuan ◽  
J. Liggio ◽  
J. Wentzell ◽  
S.-M. Li ◽  
H. Stark ◽  
...  
Keyword(s):  
Gas Phase ◽  
Oil And Gas ◽  
Gas Production ◽  
Heterogeneous Reactions ◽  
Box Model ◽  
Ionization Mass ◽  
Oil And Gas Production ◽  
Production Region ◽  
Secondary Formation ◽  
Online Measurements

Abstract. We describe the results from online measurements of nitrated phenols using a time of flight chemical ionization mass spectrometer (ToF-CIMS) with acetate as reagent ion in an oil and gas production region in January and February of 2014. Strong diurnal profiles were observed for nitrated phenols, with concentration maxima at night. Based on known markers (CH4, NOx, CO2), primary emissions of nitrated phenols were not important in this study. A box model was used to simulate secondary formation of phenol, nitrophenol (NP) and dinitrophenols (DNP). The box model results indicate that oxidation of aromatics in the gas phase can explain the observed concentrations of NP and DNP in this study. Photolysis was the most efficient loss pathway for NP in the gas phase. We show that aqueous-phase reactions and heterogeneous reactions were minor sources of nitrated phenols in our study. This study demonstrates that the emergence of new ToF-CIMS (including PTR-TOF) techniques allows for the measurement of intermediate oxygenates at low levels and these measurements improve our understanding of the evolution of primary VOCs in the atmosphere.

An Experimental Study of Controlled Gas-Phase Combustion in Porous Media for Enhanced Recovery of Oil and Gas

2001 ◽  
Author(s):  
Javier E. Sanmiguel ◽  
S. A. (Raj) Mehta ◽  
R. Gordon Moore
Keyword(s):  
Experimental Study ◽  
Porous Media ◽  
Gas Phase ◽  
Oil Recovery ◽  
Gas Flow ◽  
Oil And Gas ◽  
Enhanced Recovery ◽  
Gas Production ◽  
Operating Conditions ◽  
Operating Pressure

Abstract Gas-phase combustion in porous media has many potential applications in the oil and gas industry. Some of these applications are associated with: air injection based improved oil recovery (IOR) processes, formation heat treatment for remediation of near well-bore formation damage, downhole steam generation for heavy oil recovery, in situ preheating of bitumen for improved pumping, increased temperatures in gas condensate reservoirs, and improved gas production from hydrate reservoirs. The available literature on gas-phase flame propagation in porous media is limited to applications at atmospheric pressure and ambient temperature, where the main application is in designing burners for combustion of gaseous fuels having low calorific value. The effect of pressure on gas-phase combustion in porous media is not well understood. Accordingly, this paper will describe an experimental study aimed at establishing fundamental information on the various processes and relevant controlling mechanisms associated with gas-phase combustion in porous media, especially at elevated pressures. A novel apparatus has been designed, constructed and commissioned in order to evaluate the effects of controlling parameters such as operating pressure, gas flow rate, type and size of porous media, and equivalence ratio on combustion characteristics. The results of this study, concerned with lean mixtures of natural gas and air and operational pressures from atmospheric (88.5 kPa or 12.8 psia) to 433.0 kPa (62.8 psia), will be presented. It will be shown that the velocity of the combustion front decreases as the operating pressure of the system increases, and during some test operating conditions, the apparent burning velocities are over 40 times higher than the open flame laminar burning velocities.

Octomeric pyruvate-ferredoxin oxidoreductase from Desulfovibrio vulgaris

2007 ◽  
Vol 159 (1) ◽  
pp. 9-18 ◽  
Author(s):  
F GARCZAREK ◽  
M DONG ◽  
D TYPKE ◽  
H WITKOWSKA ◽  
T HAZEN ◽  
...  
Keyword(s):  
Desulfovibrio Vulgaris ◽  
Ferredoxin Oxidoreductase ◽  
Pyruvate Ferredoxin Oxidoreductase
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