Algae, Tree, Herbs, Bush, Shrub, Grasses, Vines, Fern, Moss, Spermatophyta, Bryophyta, Fern Ally, Flower, Photosynthesis, Eukaryote, Prokaryote, carbohydrate, vitamins, amino acids, botany, lipids, proteins, cell, cell wall, biotechnology, metabolities, enzymes, agriculture, horticulture, agronomy, bryology, plaleobotany, phytochemistry, enthnobotany, anatomy, ecology, plant breeding, ecology, genetics, chlorophyll, chloroplast, gymnosperms, sporophytes, spores, seed, pollination, pollen, agriculture, horticulture, taxanomy, fungi, molecular biology, biochemistry, bioinfomatics, microbiology, fertilizers, insecticides, pesticides, herbicides, plant growth regulators, medicinal plants, herbal medicines, chemistry, cytogenetics, bryology, ethnobotany, plant pathology, methodolgy, research institutes, scientific journals, companies, farmer, scientists, plant nutrition
Select Language:
 
 
 
 
Main Menu
Please click the main subject to get the list of sub-categories
 
Services offered
 
 
 
 
  Section: General Biotechnology / Plant Biotechnology
 
 
Please share with your friends:  
 
 

Biological Nitrogen Fixation

 
     
 

Non-Symbiotic Nitrogen Fixation

Diazotrophs
Microorganisms which pass independent life and fix atmospheric nitrogen are known as free living diazotrophs. There are two groups of such micro-organisms : bacteria and cyanobacteria (blue-green algae). Based on the mode of nutrition (carbon, nitrogen and oxygen and requirement of reducing groups) bacteria are divided into (i) aerobic bacteria (Azonomas, Azotobacter, Beijerinckia, Mycobacterium, Methylomonas), (ii) facultative anaerobic bacteria (Bacillus,  Enterobacter, Klebsiella,  etc.), (iii) anaerobic bacteria (Clostridium, Desulfovibrio, etc.) and (iv) photosynthetic bacteria (Rhodomicrobium, Rhodopseudomonas, Rhodospirillum, Chromatium, Chlorobium, etc.).

Among cyanobacteria, both heterocystous and nonheterocystous forms fix atmospheric nitrogen, for example, Anabaena, Anabaenopsis, Aulosira, Calothrix, Cylindrospermum, Gloeocapsa, Lyngbya, Nostoc, Oscillatoria, Plectonema, Scytonema, Stegonema, Tolypothrix, Trichodesmium, etc. (Alexander, 1977).

 

Content

Non-Symbiotic N2 fixation

 

Diazotrophy

 

Ecology of diazotrophs

 

Special features of diazotrophs

 

 

Sites of N2 fixation

 

 

Nitrogenase and reductants

 

 

Presence of hydrogenase

 

 

Self regulatory systems

 

Mechanism of N2 fixation

Symbiotic N2 fixation

 

Establishment of symbiosis

 

 

Host specificity and root hair curling

 

 

Infection of root hairs

 

 

Nodule development

 

 

Nodule development and maintenance

 

Factors affecting nodule development

 

Mechanism of N2 fixation in root nodules

Genetics of diazotrophs

 

Nod genes

 

Nif genes

 

 

Nif gene cloning

 

Hup genes



 
     
 
 
     



     
 
Copyrights 2012 © Biocyclopedia.com | Disclaimer