Nitrogen fixation in the rhizosphere of freshwater angiosperms

1974 ◽  
Vol 52 (1) ◽  
pp. 217-221 ◽  
Author(s):  
J. Michael Bristow
Keyword(s):  
Nitrogen Fixation ◽  
High Activity ◽  
Acetylene Reduction ◽  
Anaerobic Conditions ◽  
Aerobic Conditions

Acetylene reduction by bacteria in the rhizosphere of Glyceria borealis and Typha sp. was studied under anaerobic and aerobic conditions. Under anaerobic conditions, when roots and rhizomes were incubated with rhizosphere sediments at 25 °C without glucose, acetylene reduction to ethylene was calculated to be 37 μmol g−1 day−1 and 3.6 μmol g−1 day−1 for Glyceria and Typha respectively. The rates were generally lower under aerobic conditions. Washed roots (without sediment) also showed high activity. The reduction of acetylene to ethylene had a Q10 of 4.5 in the Glyceria system. It is estimated that N2 fixation in the rhizosphere of this species may reach 60 kg ha−1 year−1.

Nitrogen fixation and acetylene reduction in decaying conifer boles: effects of incubation time, aeration, and moisture content

1982 ◽  
Vol 12 (3) ◽  
pp. 646-652 ◽  
Author(s):  
Warwick B. Silvester ◽  
Phillip Sollins ◽  
Thomas Verhoeven ◽  
Steven P. Cline
Keyword(s):  
Nitrogen Fixation ◽  
Moisture Content ◽  
Forest Ecosystem ◽  
Acetylene Reduction ◽  
Preliminary Survey ◽  
Anaerobic Conditions ◽  
Free Living ◽  
Living Organisms ◽  
Low Activity

Free-living microaerophiles fixed 15N2 and reduced acetylene in fallen tree boles at two old-growth Pseudotsugamenziesii stands in western Oregon. Acetylene reduction was most rapid under an atmosphere of 2–10% O2, whereas under prolonged anaerobic conditions it was at or below detection limits. Acetylene reduction rates increased up to fourfold during long-term incubations in acetylene (> 12 h). Ratios of acetylene reduction to N2 fixation frequently exceeded 6.0 during such long-term incubations but averaged 3.5 when samples were incubated < 7 h; consequently, long-term incubation of low-activity material in acetylene should be avoided. A preliminary survey indicated that N2 fixation by free-living organisms in fallen boles was less than other potential N inputs to fallen boles and to the forest ecosystem.

The Reaction of Thiol Compounds with the Vitamin-K Dependent Clotting Factors

1969 ◽  
Vol 21 (03) ◽  
pp. 573-579 ◽  
Author(s):  
P Fantl
Keyword(s):  
Prothrombin Time ◽  
Vitamin K ◽  
Anaerobic Conditions ◽  
Clotting Factors ◽  
Thiol Compounds ◽  
Aerobic Conditions ◽  
One Stage ◽  
Factor Ii ◽  
Ph Dependent ◽  
The One

SummaryTreatment of human and dog oxalated plasma with 0.2 to 1.0 × 10−1 M 2.3-dithiopropanol (BAL) or dithiothreitol (DTT) at 2–4° C for 30 min results in the reduction of the vitamin-K dependent clotting factors II, VII, IX and X to the respective-SH derivatives. The reaction is pH dependent. Under aerobic conditions the delayed one stage prothrombin time can be partly reversed. Under anaerobic conditions a gradual prolongation of the one stage prothrombin time occurs without reversal.In very diluted plasma treated with the dithiols, prothrombin can be converted into thrombin if serum as source of active factors VII and X is added. In contrast SH factors VII, IX and X are inactive in the specific tests. Reoxidation to active factors II, VII, IX and X takes place during adsorption and elution of the SH derivatives. The experiments have indicated that not only factor II but also factors VII, IX and X have active-S-S-centres.

Unlocking the potential of ruthenium catalysts for nitrogen fixation with subsurface oxygen

2021 ◽  
Author(s):  
Xin Mao ◽  
Zhengxiang Gu ◽  
Cheng Yan ◽  
Aijun Du
Keyword(s):  
Nitrogen Fixation ◽  
High Activity ◽  
Ruthenium Catalysts ◽  
Ru Catalysts ◽  
Subsurface Oxygen

Decorating subsurface oxygen in Ru catalysts to achieve high activity and selectivity for N2 reduction to ammonia.

Performance of aerobic granular sludge at variable circulation rate in anaerobic–aerobic conditions

2014 ◽  
Vol 69 (11) ◽  
pp. 2252-2257 ◽  
Author(s):  
Hasnida Harun ◽  
Aznah Nor Anuar ◽  
Zaini Ujang ◽  
Noor Hasyimah Rosman ◽  
Inawati Othman
Keyword(s):  
Municipal Wastewater ◽  
Granular Sludge ◽  
Ammonia Removal ◽  
Soy Sauce ◽  
Volume Index ◽  
Aerobic Granular Sludge ◽  
Circulation Rate ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Mixed Liquor

Aerobic granular sludge (AGS) has been applied to treat a broad range of industrial and municipal wastewater. AGS can be developed in a sequencing batch reactor (SBR) with alternating anaerobic–aerobic conditions. To provide anaerobic conditions, the mixed liquor is allowed to circulate in the reactor without air supply. The circulation flow rate of mixed liquor in anaerobic condition is the most important parameter of operation in the anaerobic-AGS processes. Therefore, this study investigates the effect of circulation rate on the performance of the SBR with AGS. Two identical reactors namely R1 and R2 were operated using fermented soy sauce wastewater at circulation rate of 14.4 and 36.0 l/h, respectively. During the anaerobic conditions, the wastewater was pumped out from the upper part of the reactor and circulated back into the bottom of the reactor for 230 min. A compact and dense AGS was observed in both reactors with a similar diameter of 2.0 mm in average, although different circulation rates were adopted. The best reactor performance was achieved in R2 with chemical oxygen demand removal rate of 89%, 90% total phosphorus removal, 79% ammonia removal, 10.1 g/l of mixed liquor suspended solids and a sludge volume index of 25 ml/g.

Overexpression of the dctA gene in Rhizobium meliloti: effect on transport of C4 dicarboxylates and symbiotic nitrogen fixation

1992 ◽  
Vol 38 (6) ◽  
pp. 555-562 ◽  
Author(s):  
Vipin Rastogi ◽  
Monika Labes ◽  
Turlough Finan ◽  
Robert Watson
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Symbiotic Nitrogen Fixation ◽  
Plasmid Stability ◽  
Rhizobium Meliloti ◽  
Mrna Synthesis ◽  
Dicarboxylate Transport ◽  
Fusion Strain ◽  
Tryptophan Operon ◽  
Specific Mrna

Symbiotic nitrogen fixation may be limited by the transport of C4 dicarboxylates into bacteroids in the nodule for use as a carbon and energy source. In an attempt to increase dicarboxylate transport, a plasmid was constructed in which the Rhizobium meliloti structural transport gene dctA was fused to a tryptophan operon promoter from Salmonella typhimurium, trpPO. This resulted in a functional dctA gene that was no longer under the control of the dctBD regulatory genes, but the recombinant plasmid was found to be unstable in R. meliloti. To stably integrate the trpPO-dctA fusion, it was recloned into pBR325 and recombined into the R. meliloti exo megaplasmid in the dctABD region. The resultant strain showed constitutive dctA-specific mRNA synthesis which was about 5-fold higher than that found in fully induced wild-type cells. Uptake assays showed that [14C]succinate transport by the trpPO-dctA fusion strain was constitutive, and the transport rate was the same as that of induced control cells. Acetylene reduction assays indicated a significantly higher rate of nitrogen fixation in plants inoculated with the trpPO-dctA fusion strain compared with the control. Despite this apparent increase, the plants had the same top dry weights as those inoculated with control cells. Key words: acetylene reduction, genetic engineering, nodule, plasmid stability, promoter.

PRODUCTION AND PROPERTIES OF 2,3-BUTANEDIOL: VII. FERMENTATION OF WHEAT BY AEROBACILLUS POLYMYXA UNDER AEROBIC AND ANAEROBIC CONDITIONS

1946 ◽  
Vol 24f (1) ◽  
pp. 1-11 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Carbon Dioxide ◽  
Anaerobic Fermentation ◽  
Anaerobic Conditions ◽  
Mechanical Agitation ◽  
Fermentation Time ◽  
Aerobic Conditions ◽  
Ethanol Formation ◽  
Time Required ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Aeration by mechanical agitation of 15% wheat mash fermented by Aerobacillus polymyxa inhibited the formation of 2,3-butanediol and particularly of ethanol. Aeration of similar mashes by passage of finely dispersed air or oxygen at the rate of 333 ml. per minute per litre of mash increased the rate of formation and yield of 2,3-butanediol but inhibited ethanol formation. However, the over-all time required for the completion of fermentation was not shortened from the usual 72 to 96 hr. required for unaerated mashes. There was no evidence of a shift from fermentative to oxidative dissimilation. Under aerobic conditions, the final butanediol–ethanol ratio was approximately 3:1. Anaerobic conditions, as produced by the passage of nitrogen or hydrogen through the mash, increased the rate of formation of both butanediol and ethanol and shortened the fermentation time to about 48 hr. Under these conditions, the butanediol–ethanol ratio was reduced to about 1.3:1.0. Carbon dioxide gave a butanediol–ethanol ratio resembling that of anaerobic fermentation but did not reduce fermentation time.

Nitrogen fixation associated with 'Park' Kentucky bluegrass (Poapratensis L.)

1979 ◽  
Vol 25 (10) ◽  
pp. 1197-1200 ◽  
Author(s):  
R. C. Shearman ◽  
W. L. Pedersen ◽  
R. V. Klucas ◽  
E. J. Kinbacher
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Acetylene Reduction Activity ◽  
Controlled Environment ◽  
Nitrogen Accumulation ◽  
Reduction Activity ◽  
Significant Difference ◽  
Reduction Assay

Associative nitrogen fixation in Kentucky bluegrass (Poa pratensis L.) turfs inoculated with five nitrogen-fixing bacterial isolates was evaluated using the acetylene reduction assay and nitrogen accumulation as indicators of fixation. 'Park' and 'Nugget' Kentucky bluegrass turfs were grown in controlled environment chambers and inoculated with Klebsiella pneumoniae (W-2, W-6, and W-14), Erwinia herbicola (W-8), and Enterobacter cloacae (W-11). 'Park' inoculated with K. pneumoniae (W-6) had significant acetylene reduction activity using undisturbed turfs. Other treatments including turfs treated with heat-killed cells had no significant difference in acetylene reduction. In a second study, 'Park' and 'South Dakota Certified' turfs were grown in a greenhouse and inoculated with K. pneumoniae (W-6) and E. herbicola (W-8). 'Park' inoculated with K. pneumoniae (W-6) had increased acetylene reduction activity rates and also a greater nitrogen accumulation in aerial tissues when compared to controls. Acetylene reduction activity was correlated (r = 0.92) to nitrogen accumulation. Other treatments did not effectively increase acetylene reduction activity or nitrogen accumulation.

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