scholarly journals NICKEL INDUCED STIMULATION OF GROWTH, HETEROCYST DIFFERENTIATION, 14CO2 UPTAKE AND NITROGENASE ACTIVITY IN NOSTOC MUSCORUM

1986 ◽  
Vol 104 (1) ◽  
pp. 111-114 ◽  
Author(s):  
L. C. Rai ◽  
MEENA RAIZADA
Keyword(s):  
Nitrogenase Activity ◽  
Nostoc Muscorum ◽  
Heterocyst Differentiation ◽  
14Co2 Uptake ◽  
Stimulation Of

Investigations of nitrogenase activity in rheotrophic peat

1976 ◽  
Vol 22 (10) ◽  
pp. 1561-1566 ◽  
Author(s):  
George John Waughman
Keyword(s):  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Anaerobic Bacteria ◽  
Organic Soils ◽  
Nitrogen Fixing ◽  
Anaerobic Conditions ◽  
Time Courses ◽  
Aerobic And Anaerobic ◽  
Stimulation Of

Acetylene reduction by the peat microflora was unaffected by light, but was sensitive to temperature, with an optimum of about 30 °C. The nitrogenase was inactivated by exposure to temperatures above about 35 °C. Activity occurred in completely anaerobic conditions; the rate of ethylene production was of the order of 0.5 nmol C2H4 ml−1h−1. Experiments with time courses indicated that exposure to oxygen caused an initial inhibition of activity followed by a period in which ethylene production was stimulated to rates much higher than in the anaerobic tests; both the inhibition and stimulation appeared to be related to the level of oxygenation. It is suggested that these results could be explained by the existence of nitrogen-fixing associations of aerobic and anaerobic bacteria in the peat. The stimulation of activity caused by exposure to air indicates that care must be taken when interpreting results of the assay obtained from waterlogged organic soils.

Nitrogen fixation (C2H2reduction) as influenced by sulphate in paddy soils

1986 ◽  
Vol 106 (2) ◽  
pp. 331-336 ◽  
Author(s):  
J. L. N. Rao ◽  
V. Bajaramamohan Rao
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Nitrogenase Activity ◽  
Alluvial Soil ◽  
Paddy Soils ◽  
Alkaline Soil ◽  
Apparent Effect ◽  
Flooded Soils ◽  
Water Regimes ◽  
Stimulation Of

SUMMARYThe influence of addition of sulphate on acetylene reduction in three paddy soils differing in their properties under two water regimes was investigated in a laboratory experiment. Nitrogenase activity was high in a P-deficient alkaline soil and addition of sulphate further enhanced the activity under two water regimes, with a pronounced stimulation under non-flooded conditions. Sulphate application to submerged alluvial soil enhanced nitrogenase activity with no apparent effect under non-flooded conditions. In acid sulphate saline Pokkali soil sulphate addition had little effect on the nitrogenase activity. Sulphate addition did not result in significant changes in the soil pH and redox potential. No relationship seemed to exist between the sulphate disappearance and stimulation of nitrogenase in these soils. A differential stimulation of N2-fixing microorganisms was noticed as a result of sulphate application. Results suggest that sulphate-induced stimulation of nitrogenase activity occurs in non-flooded soils.

Bacillus cereus UW85 inoculation effects on growth, nodulation, and N accumulation in grain legumes: Field studies

2002 ◽  
Vol 82 (2) ◽  
pp. 291-298 ◽  
Author(s):  
W. John Bullied ◽  
Terry J. Buss ◽  
J. Kevin Vessey
Keyword(s):  
Bacillus Cereus ◽  
Common Bean ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Field Studies ◽  
Grain Legumes ◽  
N Accumulation ◽  
N Content ◽  
Stimulation Of

Bacillus cereus strain UW85 was assessed for growth-promotion effects on soybean and common bean in the presence and absence of rhizobial inoculation at two field sites in Manitoba in 1994. Growth promotions due to B. cereus UW85 occurred for soybean only, and only at one site. Promotions in plant emergence in soybean were apparent at 60 d after planting (DAP), but stimulations in shoot dry weight (DW), N concentration, and N content were not apparent until 90 DAP. At maturity (120 DAP), inoculation with UW85 resulted in stimulation of seed yield by 9% and seed N content by 14%. However, stimulation in growth and N parameters by UW85 treatment was proportionally greater in the absence of B. japonicum inoculation than in the presence of the rhizobial inoculant. These observations, in combination with the observations that nitrogenase activity was not stimulated by UW85 treatment, clearly indicate that the UW85-mediated stimulation of growth and N accumulation of soybean is via a generalized stimulation of plant growth, and not via a stimulation in the soybean-B. japonicum symbiosis per se. Overall, our study indicates that inoculation with UW85 has the potential of increasing soybean production in western Canada, but these effects are site specific and are not seen in common bean. Key words: Bacillus cereus UW85, common bean, Glycine max, growth-promotion, Phaseolus vulgaris, soybean

scholarly journals Functional Overlap ofhetPandhetZin Regulation of Heterocyst Differentiation inAnabaenasp. Strain PCC 7120

2018 ◽  
Vol 200 (9) ◽  
pp. e00707-17 ◽  
Author(s):  
He Zhang ◽  
Shuai Wang ◽  
Yali Wang ◽  
Xudong Xu
Keyword(s):  
Nitrogenase Activity ◽  
Terrestrial Ecosystems ◽  
Heterocyst Differentiation ◽  
Content Type ◽  
Reverse Transcription Quantitative Pcr ◽  
Dependent Cell ◽  
Major Factors ◽  
Pcc 7120 ◽  
Relationship Of

ABSTRACTHetR plays a key role in regulation of heterocyst differentiation and patterning inAnabaena. It directly regulates genes involved in heterocyst differentiation (such ashetPandhetZ), genes involved in pattern formation (patA), and many others. In this study, we investigated the functional relationship ofhetPandhetZand their role in HetR-dependent cell differentiation. Coexpression ofhetPandhetZfrom the promoter ofntcA, which encodes the global nitrogen regulator, enabled ahetRmutant to form heterocysts with low aerobic nitrogenase activity. Overexpression ofhetZrestored heterocyst differentiation in ahetPmutant and vice versa. Overexpression ofhetRrestored heterocyst formation in either ahetPor ahetZmutant but not in ahetZ hetPdouble mutant. The functional overlap ofhetPandhetZwas further confirmed by reverse transcription-quantitative PCR (RT-qPCR) and transcriptomic analyses of their effects on gene expression. In addition, yeast two-hybrid and pulldown assays showed the interaction of HetZ with HetR. HetP and HetZ are proposed as the two major factors that control heterocyst formation in response to upregulation ofhetR.IMPORTANCEHeterocyst-forming cyanobacteria contribute significantly to N2fixation in marine, freshwater, and terrestrial ecosystems. Formation of heterocysts enables this group of cyanobacteria to fix N2efficiently under aerobic conditions. HetR, HetP, and HetZ are among the most important factors involved in heterocyst differentiation. We present evidence for the functional overlap ofhetPandhetZand for the key role of the HetR-HetP/HetZ circuit in regulation of heterocyst differentiation. The regulatory mechanism based on HetR, HetP, and HetZ is probably conserved in all heterocyst-forming cyanobacteria.

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