Nitrogen and Sulphate AssimilationPresented by : Devi wanie Mawaddah Nasution Remli N.Simarmata Sri Hayuni Wiwik Simanjuntak Biology Bilingual 09 Nitrogen Cycle Presented by : Wiwik simanjuntak NITROGEN Nitrogen a chemical element that has the symbol N. Atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere. Discovered by Scottish physician Daniel Rutherford, in 1772. Source Figure 1 Nitrogen cycle Introduction Source of Nitrogen: ² NO3 (Nitrate); Most of the plant. Source: Industrial burn, Volcanic activity and Forest burn ² NH4 (Ammoniac); For Corniferae and Poaceae family. Source : Ozone by thunder light and UV radiation. Forms of Nitrogen Urea CO(NH2)2 Ammonia NH3 (gaseous) Ammonium NH4 Nitrate NO3 Nitrite NO2 Atmospheric Dinitrogen N2 Organic N Roles of Nitrogen Plants and bacteria use nitrogen in the form of NH4+ or NO3 It serves as an electron acceptor in anaerobic environment Nitrogen is often the most limiting nutrient in soil and water. Nitrogen is a key element for amino acids nucleic acids (purine, pyrimidine) cell wall components of bacteria (NAM). Nitrogen Cycles Ammonification/mineralization Immobilization Nitrogen Fixation Nitrification Denitrification Ammonification or Mineralization N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Mineralization or Ammonification Decomposers: earthworms, termites, slugs, snails, bacteria, and fungi Uses extracellular enzymes initiate degradation of plant polymers Microorganisms uses: Proteases, lysozymes, nucleases to degrade nitrogen containing molecules Plants die or bacterial cells lyse release of organic nitrogen Organic nitrogen is converted to inorganic nitrogen (NH3) When pH<7.5, converted rapidly to NH4 Example: Urea NH3 + 2 CO2 Immobilization The opposite of mineralization Happens when nitrogen is limiting in the environment Nitrogen limitation is governed by C/N ratio C/N typical for soil microbial biomass is 20 C/N < 20 Mineralization C/N > 20 Immobilization Nitrogen Fixation Presented by : Mawaddah Nitrogen Fixation N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Nitrogen fixation This is the first step in the nitrogen cycle and it involves the reduction of atmospheric nitrogen gas (N2) to ammonia (NH3). This can only be done biologically by a small and highly specialized group of microorganisms. The enzyme Nitrogenase catalyzes the reduction of diatomic nitrogen gas (in the atmosphere) to ammonia. N2 + 6 e- + 8H+ ---Nitrogenase-- & Fe, Mo 2 NH3 + H2 Nitrogen fixing organisms All the nitrogen-fixing organisms are prokaryotes (bacteria). Some of them live independently of other organisms - the free-living nitrogen-fixing bacteria. Others live in intimate symbiotic associations with plants or with other organisms (e.g. protozoa). Microorganisms fixing Azobacter Beijerinckia Azospirillum Clostridium Cyanobacteria Require the enzyme nitrogenase Inhibited by oxygen Inhibited by ammonia (end product) Bacterial Fixation Occurs mostly in salt marshes Is absent from low pH peat of northern bogs Cyanobacteria found in waterlogged soils Nitrogen fixing associations Nodulation The nodule is a highly organised structure with membranous sacs containing colonies of the bacteria. It is in direct connection with the vascular system of the plant. Nitrogen fixing associations Nodulation Once the nodule is established, the differentiated bacteria (they become non-motile bacteroids) living in the infected plant cells, reduce atmospheric nitrogen to ammonia which is excreted to the plant cell and is, in turn, assimilated to organic nitrogen (proteins and amino acids) by the plant. The plant provides the bacteroid with carbon skeletons (photosynthate) which are required by Rhizobium. Nitrogen fixing associations Nodulation This symbiosis is a specific process, a certain species of Rhizobium can only nodulate a certain type of legume, for example: R. etli nodulates beans (Phaseolus), R. meliloti nodulates alfalfa (Medicago). The bacterial nitrogenase enzyme complex is responsible for the reduction of gaseous N2 to ammonia. Different nitrogenase enzyme systems have been found in different microorganisms. Nitrogen fixing associations Nodulation Associations are also made with certain woody plants. This occurs via Frankia, which is a genus of the bacterial group termed Actinomycetes. Included in this group are the common soil-dwelling Streptomyces species which produce many of the antibiotics. Frankia species are slow-growing in culture, and require specialised media, suggesting that they are specialised symbionts. ENZYMATIC MECHANISM OF NITROGEN FIXATION 6MgADP + 6Pi Enzymatic Mechanism of Nitrogen Fixation The reduced ferredoxin, which supplies electrons for this process is generated by photosynthesis, respiration or fermentation. Functional conservation between the nitrogenase proteins. Nitrogen fixation occurs when the Fe protein of one species is mixed with the Mo-Fe protein of another bacterium, even if the species are very distantly related. The nitrogenase enzyme complex is highly sensitive to oxygen. Denitrification N2 N2O NH4 NO2 R-NH2 NO NO2 NO3 Denitrification Removes a limiting nutrient from the environment 4NO3 + C6H12O6 2N2 + 6 H20 Inhibited by O2 Not inhibited by ammonia Microbial reaction Nitrate is the terminal electron acceptor Assimilation of Nitrate Ion and Ammonium Presented by : Sri Hayuni Figure 2. Plant absorb the nitrogen compound from the root in form of ammonium and nitrate. Nitrate Assimilation Absorb nitrate or ammonium ions from the soil via root hairs. Have a mutualistic relationship with rhizobia. Some nitrogen is assimilated in the form of ammonium ions directly from the nodules. Nitrogen Cycle Oxidation Number of N Reaction Type N2(g) -------> NH4+(aq) -------> NO2-(aq) -------> NO3-(aq) 0 -------> -3 -------> +3 -------> +5 reduction oxidation oxidation Nitrate Assimilation Some plant, can synthesis organic nitrogen in root by it self. NO3 Amino Acid and Amida Plant: Betulaceae, Casuarinaceae, Eleagnaceae, Moraceae, Leguminosae (Fabaceae) and Myricaceae families. Plant root term called Cluster Root or Proteoid Root. Can symbiotic to fixed atmospheric N2. Nitrate Assimilation Another plants, need the supply of treetops for get nitrogen supply. Example: Xanthium stumanium. Almost not fixative NO3 at all. See book, page 210 for comparing another plants. Figure 4. Xanthium stumanium. Nitrate Assimilation Nitrate Reduction Process Reaction: NO3 8electrons 10 H p NH 4 3H 2O Require amounts of H+ ions. Causes : Increas of cell pH Half ions neutralize while ammonium convert to protein. Malate acid formed from glucose or amilum. Nitrate Assimilation Nitrate Reduction Process 2 steps reactions: . First Step: NO3 NADH 2 p NO2 NAD H 2O Nitrate reductase Catalyze by: nitrate reductase enzyme. Occurs in cytosol. Nitrate Assimilation Nitrate Reduction Process 2 steps of reaction: , Second reaction: Nitrite convert become ammonium ion. Occurs in: Chloroplast at leaf Protoplastida at root Require 6 electrons from H2O. Nitrate Assimilation Nitrate Reduction Process 2 steps of reaction: , Second reaction: 3H 2O 6 Fd ( Fe 3 ) light p 1.5O2 6 H 6 Fd ( Fe 2 ) NO2 6 Fd ( Fe 2 ) 8 H p NH 4 6 Fd ( Fe 3 ) 2 H 2O NO2 3H 2O 2 H Light p NH 4 1.5O2 2 H 2O ««. R 1 ««. R 2 Nitrate Assimilation Converting Become Organic Compound Ammonium actually poisonous, inhibit ATP formation. Uncoupler Converted again into another organic compound. Glutamine Glutamine syntase enzyme Asparangin Asparagin syntase enzyme Nitrate Assimilation Converting Become Organic Compound Glutamine; storage nitrogen in tuber. E.g. Potato, beet, carrot. Formed: Glutamate acid and NH4 from protein decomposition. Figure 5. Beet tuber rich consist of glutamine Nitrate Assimilation Converting Become Organic Compound Asparagin; storage nitrogen found in legumes, nut, seed, soy, whole grain plant. Nodule of Root at legumes Nitrate Assimilation Transmination Reaction Accomplished by enzymes called transaminases or aminotransferases. Reaction between an amino acid and an alpha-keto acid. The amino group is transferred from the former to the latter; this results in the amino acid being converted to the corresponding keto acid, while the reactant -keto acid is converted to the corresponding amino acid. Nitrogen Transformation Presented by : Devi Wani Nitrogen Transformation During Seed Germination O Protein reserve keeps at the aleuron layer of the seed . O Also storage place for fosfat, magnesium and calsium. O Need for the germinate the seed. O Process start by imbibitions of the seed, and catalyze the enzyme for seed germination Nitrogen Transformation During Seed Germination Protein reserve lining at aleuron layer Nitrogen Transformation During Seed Germination O Process: O Protein in Aleuron layer hydrolyzed by proteinase and peptidase enzyme to be converted become amino acid and amida. O Membrane of Aleuron fuse to form tonoplast surrounding the vacuole. O Some amino acid and amida start to form new protein which being transfer to the root and tip of tree. O Protein need for cell division in meristematic Nitrogen Transformation During Plant Growth O Most nitrogen formed as protein. O At leaf nitrogen concentrated in chlorophyll. O There is also nitrogen storage at seed. O Nitrogen at leaf, transferred to aleuron layer during seed formation. O Required a lot of Rubisco enzyme (Photosynthesis enzyme), causes decreasing photosynthesis rate during seed formation. Called as ´Self Destroyingµ Nitrogen Transformation During Plant Growth O At wheat plants, 85% nitrogen looses during seed formation. O Nitrogen being transferred to the reproductive system. O At annual wet plant, nitrogen transferred again to root and tip tree after nitrogen required in seeds finish. O So nitrogen still available at the next reproductive seasons. Nitrogen Transformation During Plant Growth O Nitrogen storage mostly at fruits and seeds. O Fruits get nutrient from the storage of nitrogen which transferred by phloem from the axial leaves. O Apple plants, looses half of nitrogen reserve from the leaf at that process. Sulphate Assimilation Presented by : remli nelmian Sulphate assimilation Sulfur is macronutrients required by plants. It is found in organic form in amino acids like Cysteine and Methionine and in a variety of metabolites. In inorganic form : Sulphate ion (SO42- ) in soil SO42- is a major anionic component of vacuolar sap; therefore, it does not necessarily enter the assimilation stream Gaseous sulfur dioxide (SO2) is readily absorbed and assimilated by leaves, but it is significant as a nutrient source only in industrial areas with air pollution. Sulfate ion taken up by the roots is the major source for growth; it is reduced to sulfide and then can be metabolized further and incorporated into cysteine. SO42- + ATP + 8 e- + 8 H+ S2- + 4 H2O + AMP + PiP Sulphate ion reduction take place in roots and tip of plant, some transported by xylem to leaf in sulphate ion form Reduction in Chloroplast is : first, sulfat group from APS move it to Sulfur atom from two acceptor molecul by Sulphotransperase APS enzyme (may glutation shows as GSH and Tioreduksin). After GSH accept sulfat from APS, formed G-S-SO3-. Then, S in SO3 group from G-S-SO3- reducted by Fereduksin produce G-S-SH. SH group will release as free Sulfida or changed become Cystein directly. Assimilation step The first step of assimilation of SO42- is SO42- reaction with ATP produce Adenosin5·-Phosphosulphate (APS) and Phirophosphate (PiP). This stage catalyze by Sulfurilase ATP. PiP hydrolyze to two iP by Phirophosphatase enzyme and then used in Mitochondria or Chloroplast for ATP regeneration.
Report "Nitrogen and Sulphate Assimilation Presentation"