Fluoroacetate Metabolism in Gloeocapsa sp. LB795 and its Relationship to Acetylene Reduction (Nitrogen Fixation)

Gallon, John; Ul-Haque, M. Ikram; Chaplin, Alan E.

doi:10.1099/00221287-106-2-329

Cited by 23 publications

(20 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An axenic cultiire of Gloeothece sp. PC 6909 was a generous gift from Dr R. Rippka, Institut Pasteur, Paris, and was grown at 25 "C under constant illumination (1 klx) in ASM-1 medium free of combined nitrogen (Gallon et al, 1978). Stock cultures were maintained on agar slopes of ASM-1 medium solidified with agar (1 %, w/v).…”

Section: Methodsmentioning

confidence: 99%

Nitrogen Fixation by Gloeothece sp. PCC 6909: Respiration and Not Photosynthesis Supports Nitrogenase Activity in the Light

et al. 1986

Self Cite

View full text Add to dashboard Cite

Nitrogenase activity of suspensions of the unicellular cyanobacterium Gloeothece sp. PCC 6909 plotted against the concentration of dissolved 0, (do,) resulted in a bell-shaped curve, both in the light and in the dark, with optima of 25 or 80 ~M -O , depending on the age of the culture, At the optimum d o 2 , nitrogenase activity [typically 4 to 6 nmol C2H, (mg protein)-' min-l] was similar in the light or in the dark. Alteration of light intensity from zero to 2 klx, or addition of 3-(3,4-dichlorophenyl)-l, 1-dimethylurea (DCMU), had no effect on nitrogenase activity. At 1 klx the ADP/ATP ratio was 0.2 and showed only a marginal increase as the d o 2 was increased. However, a high level of illumination (30 klx) stimulated or inhibited nitrogenase activity, depending on the external do,, presumably as a consequence of changes in the intracellular O2 concentration; in the presence of DCMU, activity increased twofold, independent of do,.In the dark, the dependence of the rate of respiration on O2 concentration suggested the presence of three 0,-uptake systems with apparent K, values of 1 PM, 5 p~ and 25 p~. The ADP/ATP ratio under anaerobic conditions was 0.47 and showed a marked decrease as d o 2 was increased to 25 VM. A CN-insensitive respiratory activity, which neither supported nitrogenase activity nor was coupled to ATP synthesis, was associated with the system with the apparent K, of 5 p~. The dependence of the specific activity of nitrogenase on d o 2 indicated that both the high affinity ( K , 1 WM) and low affinity ( K , 25 p~) O2-uptake systems contributed ATP or reductant for N,-fixation. KCN (2.5 mM) completely inhibited nitrogenase activity in the dark and at moderate levels of illumination and d o 2 . We conclude that respiration is the major source of reductant and ATP for nitrogenase activity both in the dark and in the light, but that photosystem I can contribute ATP at very high levels of illumination.

show abstract

Section: Methodsmentioning

confidence: 99%

Nitrogen Fixation by Gloeothece sp. PCC 6909: Respiration and Not Photosynthesis Supports Nitrogenase Activity in the Light

et al. 1986

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, these were never apparent when samples were examined microscopically but appeared only after prolonged incubation (7 to 8 weeks) on agar plates. Growth of these species occurred only when the agar plates were made up with ASM-1 medium (Gallon et al, 1978) and never if the medium was supplemented with artificial sea water. It is therefore possible that Anabaena spp.…”

Section: Landimore Marshmentioning

confidence: 99%

“…and Nostoc sp. were grown in liquid culture at 25 °C in modified ASM-1 medium (Gallon, Ul-Haque & Chaplin, 1978) on a cycle of alternating 12 h l.gh,/12 h darkness. During the light phase, the photon flux was f " h H K • ^'"'^''"'"'' f-a^^^^ ^^' 8™*" *" *"= nitrogen-free medium described by Khamees ei a/.…”

Section: Isolation and Growth Of Cyanobacteriamentioning

confidence: 99%

THE DIURNAL PATTERN OF DINITROGEN FIXATION BY CYANOBACTERIA IN SITU

1987

View full text Add to dashboard Cite

SUMMARYThe diurnal patterns of cyanobacterial acetylene reduction (nitrogen fixation) and seasonal variations in these patterns were investigated in situ on a salt marsh and in a limestone cave. In the field, the non-heterocystous species fixed Ng mainly at night, while heterocystous species fixed Ng mainly during the day. These basic patterns could he infiuenced hy environmental conditions such as O^ availability and temperature. No acetylene reduction was observed in December, January or February.

show abstract

“…Stock cultures of Aphanizomenon sp. were maintained in ASM-1 medium free of combined N (Gallon et al, 1978) whereas Nodularia SN34D and Nodularia SN15A were grown in N-free MN medium (Van Baalen, 1962), modified according to Gallon et al (1991). Cultures were maintained with shaking at 17mC and illuminated at 30 µmol m −# s −" under 12 h light : 12 h darkness.…”

Section: Growth and Maintenance Of Laboratory Culturesmentioning

confidence: 99%

Nitrogen fixation by Baltic cyanobacteria is adapted to the prevailing photon flux density

et al. 2000

Self Cite

View full text Add to dashboard Cite

N # fixation, measured as acetylene reduction, was studied in laboratory cultures and in natural assemblages (both as a mixed population and as individually picked colonies) of the heterocystous cyanobacteria Aphanizomenon sp. and Nodularia spp. from the Baltic Sea. During a diurnal cycle of alternating light and darkness, these organisms reduced acetylene predominantly during the period of illumination, although considerable activity was also observed during the dark period. In both laboratory cultures and natural populations N # fixation was saturated below a photon flux density of 600 µm −# s −" . In cyanobacterial blooms in the Baltic Sea, nitrogenase activity was mostly confined to the surface layers. Samples collected from greater depths did not possess the same capacity for acetylene reduction as samples from the surface itself, even when incubated at the photon flux density prevailing in surface waters. This suggests that, with respect to N # fixation, Baltic cyanobacteria are adapted to the intensity of illumination that they are currently experiencing.

show abstract

Fluoroacetate Metabolism in Gloeocapsa sp. LB795 and its Relationship to Acetylene Reduction (Nitrogen Fixation)

Cited by 23 publications

References 10 publications

Nitrogen Fixation by Gloeothece sp. PCC 6909: Respiration and Not Photosynthesis Supports Nitrogenase Activity in the Light

Nitrogen Fixation by Gloeothece sp. PCC 6909: Respiration and Not Photosynthesis Supports Nitrogenase Activity in the Light

THE DIURNAL PATTERN OF DINITROGEN FIXATION BY CYANOBACTERIA IN SITU

Nitrogen fixation by Baltic cyanobacteria is adapted to the prevailing photon flux density

Contact Info

Product

Resources

About