scholarly journals Effects of Disruption of Homocitrate Synthase Genes on Nostoc sp. Strain PCC 7120 Photobiological Hydrogen Production and Nitrogenase

2007 ◽  
Vol 73 (23) ◽  
pp. 7562-7570 ◽  
Author(s):  
Hajime Masukawa ◽  
Kazuhito Inoue ◽  
Hidehiro Sakurai
Keyword(s):  
Nitrogen Fixation ◽  
Hydrogen Production ◽  
Double Mutant ◽  
Production Systems ◽  
Combined Nitrogen ◽  
Nitrogen Fixation Activity ◽  
Production Activity ◽  
Homocitrate Synthase ◽  
High Level ◽  
Pcc 7120

ABSTRACT In the case of nitrogenase-based photobiological hydrogen production systems of cyanobacteria, the inactivation of uptake hydrogenase (Hup) leads to significant increases in hydrogen production activity. However, the high-level-activity stage of the Hup mutants lasts only a few tens of hours under air, a circumstance which seems to be caused by sufficient amounts of combined nitrogen supplied by active nitrogenase. The catalytic FeMo cofactor of nitrogenase binds homocitrate, which is required for efficient nitrogen fixation. It was reported previously that the nitrogenase from the homocitrate synthase gene (nifV) disruption mutant of Klebsiella pneumoniae shows decreased nitrogen fixation activity and increased hydrogen production activity under N2. The cyanobacterium Nostoc sp. strain PCC 7120 has two homocitrate synthase genes, nifV1 and nifV2, and with the ΔhupL variant of Nostoc sp. strain PCC 7120 as the parental strain, we have constructed two single mutants, the ΔhupL ΔnifV1 strain (with the hupL and nifV1 genes disrupted) and the ΔhupL ΔnifV2 strain, and a double mutant, the ΔhupL ΔnifV1 ΔnifV2 strain. Diazotrophic growth rates of the two nifV single mutants and the double mutant were decreased moderately and severely, respectively, compared with the rates of the parent ΔhupL strain. The hydrogen production activity of the ΔhupL ΔnifV1 mutant was sustained at higher levels than the activity of the parent ΔhupL strain after about 2 days of combined-nitrogen step down, and the activity in the culture of the former became higher than that in the culture of the latter. The presence of N2 gas inhibited hydrogen production in the ΔhupL ΔnifV1 ΔnifV2 mutant less strongly than in the parent ΔhupL strain and the ΔhupL ΔnifV1 and ΔhupL ΔnifV2 mutants. The alteration of homocitrate synthase activity can be a useful strategy for improving sustained photobiological hydrogen production in cyanobacteria.

scholarly journals Heterocyst-Specific Expression of patB, a Gene Required for Nitrogen Fixation in Anabaena sp. Strain PCC 7120

2003 ◽  
Vol 185 (7) ◽  
pp. 2306-2314 ◽  
Author(s):  
Kathryn M. Jones ◽  
William J. Buikema ◽  
Robert Haselkorn
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Removal ◽  
Deletion Mutant ◽  
Filamentous Cyanobacterium ◽  
Specific Expression ◽  
Growth And Survival ◽  
Combined Nitrogen ◽  
Anabaena Sp ◽  
Pcc 7120 ◽  
Initial Pattern

ABSTRACT The patB gene product is required for growth and survival of the filamentous cyanobacterium Anabaena sp. strain PCC 7120 in the absence of combined nitrogen. A patB::gfp fusion demonstrated that this gene is expressed exclusively in heterocysts. patB mutants have a normal initial pattern of heterocyst spacing along the filament but differentiate excess heterocysts after several days in the absence of combined nitrogen. Expression of hetR and patS, two critical regulators of the heterocyst development cascade, are normal for patB mutants, indicating that patB acts downstream of them in the differentiation pathway. A patB deletion mutant suffers an almost complete cessation of growth and nitrogen fixation within 24 h of combined nitrogen removal. In contrast, a new PatB mutant that is defective in its N-terminal ferredoxin domain, or a previously described mutant that has a frameshift removing its C-terminal helix-turn-helix domain, grows very slowly and differentiates multiple contiguous heterocysts under nitrogen-deficient conditions.

High level of hydrogen production activity achieved for hydrogenase encapsulated in sol–gel material doped with carbon nanotubes

2010 ◽  
Vol 20 (6) ◽  
pp. 1065 ◽  
Author(s):  
Oleg A. Zadvorny ◽  
Amy M. Barrows ◽  
Nikolay A. Zorin ◽  
John W. Peters ◽  
Timothy E. Elgren
Keyword(s):  
Carbon Nanotubes ◽  
Hydrogen Production ◽  
Sol Gel ◽  
Production Activity ◽  
High Level

Consent

2018 ◽  
Author(s):  
Martin Krzywdzinski
Keyword(s):  
Production Systems ◽  
Employee Behavior ◽  
Labor Disputes ◽  
Performance Expectations ◽  
The Third ◽  
The Core ◽  
Core Requirements ◽  
High Level

This chapter deals with the dependent variable of the study: consent. It analyses workplace consent in Russia and China using three indicators that refer to the core requirements of the production systems in automotive companies regarding employee behavior: first, standardized work; and second, compliance with expectations in terms of flexibility, cooperation, and a commitment to improving processes. The third indicator of consent (or the lack of it) is the absence or presence of open criticism, resistance, and labor disputes. The chapter reveals significant and unexpected differences between the Chinese and Russian sites on all three indicators. While the Chinese factories exhibit (with some variance between the companies), a relatively high level of consent, the Russian plants have problems with standardized work, the acceptance of performance expectations, and to some extent with labor disputes.

scholarly journals Diversity of Cowpea [Vigna unguiculata (L.) Walp] Landraces in Mozambique: New Opportunities for Crop Improvement and Future Breeding Programs

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 991
Author(s):  
Ana Maria Figueira Gomes ◽  
David Draper ◽  
Nascimento Nhantumbo ◽  
Rafael Massinga ◽  
José C. Ramalho ◽  
...  
Keyword(s):  
Vigna Unguiculata ◽  
Production Systems ◽  
Crop Improvement ◽  
Morphological Diversity ◽  
Ecological Zones ◽  
Nutrition Security ◽  
Food And Nutrition ◽  
High Level ◽  
Nutrition Sensitive

Cowpea (Vigna unguiculata) is a neglected crop native to Africa, with an outstanding potential to contribute to the major challenges in food and nutrition security, as well as in agricultural sustainability. Two major issues regarding cowpea research have been highlighted in recent years—the establishment of core collections and the characterization of landraces—as crucial to the implementation of environmentally resilient and nutrition-sensitive production systems. In this work, we have collected, mapped, and characterized the morphological attributes of 61 cowpea genotypes, from 10 landraces spanning across six agro-ecological zones and three provinces in Mozambique. Our results reveal that local landraces retain a high level of morphological diversity without a specific geographical pattern, suggesting the existence of gene flow. Nevertheless, accessions from one landrace, i.e., Maringué, seem to be the most promising in terms of yield and nutrition-related parameters, and could therefore be integrated into the ongoing conservation and breeding efforts in the region towards the production of elite varieties of cowpea.

scholarly journals Transcriptomics differentiate two novel bioactive strains of Paenibacillus sp. isolated from the perennial ryegrass seed microbiome

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tongda Li ◽  
Ross Mann ◽  
Jatinder Kaur ◽  
German Spangenberg ◽  
Timothy Sawbridge
Keyword(s):  
Nitrogen Fixation ◽  
Secondary Metabolite ◽  
Perennial Ryegrass ◽  
Fusarium Verticillioides ◽  
In Vitro Assays ◽  
Colletotrichum Graminicola ◽  
Nitrogen Fixation Activity ◽  
Auxin Production ◽  
Paenibacillus Sp

AbstractPaenibacillus species are Gram-positive bacteria that have been isolated from a diverse array of plant species and soils, with some species exhibiting plant growth-promoting (PGP) activities. Here we report two strains (S02 and S25) of a novel Paenibacillus sp. that were isolated from perennial ryegrass (Lolium perenne) seeds. Comparative genomics analyses showed this novel species was closely related to P. polymyxa. Genomic analyses revealed that strains S02 and S25 possess PGP genes associated with biological nitrogen fixation, phosphate solubilisation and assimilation, as well as auxin production and transportation. Moreover, secondary metabolite gene cluster analyses identified 13 clusters that are shared by both strains and three clusters unique to S25. In vitro assays demonstrated strong bioprotection activity against phytopathogens (Colletotrichum graminicola and Fusarium verticillioides), particularly for strain S02. A transcriptomics analysis evaluating nitrogen fixation activity showed both strains carry an expressed nif operon, but strain S02 was more active than strain S25 in nitrogen-free media. Another transcriptomics analysis evaluating the interaction of strains with F. verticillioides showed strain S02 had increased expression of core genes of secondary metabolite clusters (fusaricidin, paenilan, tridecaptin and polymyxin) when F. verticillioides was present and absent, compared to S25. Such bioactivities make strain S02 a promising candidate to be developed as a combined biofertiliser/bioprotectant.

Nonaqueous synthesis of TiO2–carbon hybrid nanomaterials with enhanced stable photocatalytic hydrogen production activity

2015 ◽  
Vol 3 (18) ◽  
pp. 10060-10068 ◽  
Author(s):  
Yijun Yang ◽  
Ye Yao ◽  
Liu He ◽  
Yeteng Zhong ◽  
Ying Ma ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Hydrogen Production ◽  
Water Splitting ◽  
Hybrid Nanomaterials ◽  
Photocatalytic Hydrogen Production ◽  
Production Activity ◽  
Nonaqueous Synthesis

Enhanced and stable photocatalytic activity upon water splitting was demonstrated in a series of TiO2–carbon hybrid nanomaterials, which were derived from oleylamine wrapped ultrathin TiO2 nanosheets.

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