MICROORGANISMS AND NITROGEN CYCLE

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NITROGEN CYCLE

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MICROORGANISMS AND NITROGEN CYCLE

  1. 1. NITROGEN CYCLE PANKAJ Microbiology
  2. 2. CONTENTS INTRODUCTION MAJOR MICROBIAL NITROGEN TRANSFORMATION MECHANISM OF NITROGEN CYCLE BY ENZYME ROLE OF ELECTRON IN NITROGEN CYCLE Nif GENES DEFIENCY SYMPTOMS
  3. 3. INTRODUCTION The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out via both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification. The majority of Earth's atmosphere (approximately 78%) is nitrogen.
  4. 4. MAJOR MICROBIAL N2 TRANSFORMATION Nitrogen fixation Nitrification Denitrification Anammox Ammonification
  5. 5. NITROGEN FIXATION Atmospheric nitrogen by nitrogen fixing bacteria to yield ammonia. N2+8H =NH3+H2 ( Cynobacteria)
  6. 6. NITRIFICATION The atmospheric nitrogen is fixed by nitrogen fixing bacteria to yield ammonia. This ammonia is used by living microorganism and converted into nitrate.  NH4+ = NO2- ( Nitrosomonas) NO2- = NO3- ( Nitrobactor)
  7. 7. Denitrification The conversion of nitrate to nitrogen under anaerobic condition is known as denitrification. NO3- = N2 (Bacillus, Prococus, pseudomonas)
  8. 8. ANAMMOX In this biological process, nitrite and ammonium are converted directly into dinitrogen gas. This process contributes up to 50% of the dinitrogen gas produced in the oceans. It is thus a major sink for fixed nitrogen and so limits oceanic primary productivity. The overall catabolic reaction is: NH4+ + NO2− → N2 + 2H2O. (Brocadia) The bacteria that perform the anammox process belong to the bacterial phylum planctomycetes of which Planctomyces and Pirellula are the best known genera.
  9. 9. AMMONIFICATION Ammonia Is released during the decomposition of organic nitrogen compound such as amino acids and nucleotides a process called ammonification. Organic N2 =NH4+ ( Rhizobium)
  10. 10. Nitrogenase complex 1. Dinitrogenase reductase 2. Dinitrogenase
  11. 11. Nif Genes The nif gene is the gene responsible for the coding of proteins related and associated with the fixation of atmospheric nitrogen into a form of nitrogen available to plants. These genes are found in nitrogen fixing bacteria and cyanobacteria.
  12. 12. DEFICIENCY SYMPTOMS Chlorosis appears in older leaves. Dormancy of lateral buds . Delaying of flowering .
  13. 13. Reference Burford, J.R., and J.M. Bremner. 1975. Relationships between the denitrification capacities of soils and total, water-soluble and readily decomposable soil organic matter. Soil Biochem. 7:389-394 Marschner, H. 1995. Mineral Nutrition in Higher Plants. Academic Press, London. Tisdale, S.L., W.L. Nelson, J.D. Beaton, and J.L. Havlin. 1993. Soil Fertility and Fertilizers. MacMillan Publishing Co., New York, N.Y. Brock 8th edition . Nitrogen cycle.page 532 Lehninger fourth edition.nitrogen cycle page no. 834
  14. 14. Thank You

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