DIVERSITY IN MICROBIAL ACQUISITION OF ENERGY.pptx

Detailed presentation on how different microorganisms acquire energy.

1. DIVERSITY IN MICROBIAL ACQUISITION OF ENERGY

2. Microorganism Metabolism Autotrophic Photoautotrophic , Chemoautotrophic , Heterotrophic

3. Bacterial Metabolism Autotroph : Photosynthetic bacterial Chemoautotrophic bacteria Heterotroph : Parasite Saprophyte

4. Autotrophic Microorganisms The autotrophic mode of nutrition may be defined as the organisms which are capable of synthesizing their food by themselves from organic and inorganic substances. They are the producers in a food chain. The autotrophs can be further divided into two subgroups, i.e. Photoautotrophs, and chemoautotrophs. 

5. Autotrophic Microorganisms An autotroph is an organism capable of making nutritive organic molecules from inorganic materials. It could be through photosynthesis (involving light energy) or chemosynthesis (involving chemical energy). Organisms that synthesize food molecules through photosynthesis are referred to as photoautotrophs whereas those that do so through chemosynthesis are called chemoautotrophs . Another name for an autotroph is autophyte . It can also be called a producer for its capacity to produce its own food . They are the producers in a food chain . Autotrophs are capable of manufacturing their own food by photosynthesis or by chemosynthesis . Thus, they may be classified into two major groups : Photoautotrophs Chemoautotrophs

6. Photoautotrophic Acquisition of Energy

7. Photosynthesis Photosynthesis proceeds in two phases: The light-dependent reactions, which proceed only in the presence of sunlight, Light-independent reactions, which proceed regardless of the lighting conditions

8. Photosynthesis: The Earth’s Lifeline The general reactions of photosynthesis, divided into two phases: Light-dependent reactions and light-independent reactions. The dependent reactions require light to activate chlorophyll pigment and use the energy given off during activation to split an H2O molecule into oxygen and hydrogen, producing ATP and NADPH. The light-independent reactions, which occur either with or without light, utilize ATP and NADPH produced during the light reactions to fix CO2 into organic compounds such as glucose .

9. Chloroplast Light O 2 Sugars CO 2 Light- Dependent Reactions Calvin Cycle NADPH ATP ADP + P NADP + Chloroplast : Stages of Photosynthesis (1 st ) Light-dependent Reactions occur in grana (2 nd) Light-independent Can happen in light Or Dark

10. Light-Dependent Reactions --oxygenic-- These light-dependent reactions are catabolic ( energy producing ) reactions, which pave the way for the next reactions, the light-independent reactions, which use the extracted energy for synthesis (anabolic) for light-independent reactions

11. Light-Dependent Reactions -- oxygenic- - In prokaryotes, there exists two photo systems as two separate complexes called photosystem I (P700) and photosystem II (P680 ). Both systems contain chlorophyll and they are simultaneously activated by light, but the reactions in photosystem II help drive photosystem I. Together the systems are activated by light, transport electrons, pump hydrogen ions, and form ATP and NADPH, which is fed into the Calvin Cycle 1 When light activates photosystem II, it sets up a chain reaction , in which electrons are released from chlorophyll . 2 These electrons are transported along a chain of carriers to photosystem I. 3 The empty position in photosystem II is replenished by photolysis of H2O . The products of photolysis are O2 and H + . 4 Pumping of H + into the interior of the granum produces conditions for ATP to be synthesized . 5 The final electron and H acceptor is NADP, which receives these from photosystem I. 6 Both NADPH and ATP are fed into the stroma for the Calvin cycle .

12. Light-Independent Reactions Fixing of carbon into organic form in Calvin Cycle using the energy (ATP and NADPH) released by the light reactions .

13. The subsequent photosynthetic reactions that do not require light occur in the chloroplast stroma or the cytoplasm of cyanobacteria. These reactions use energy produced by the light phase to synthesize glucose by means of the Calvin Cycle

14. The Calvin cycle . SUMMARY This is the main events of the reactions in photosynthesis that do not require light. It is during this cycle that carbon is fixed into organic form using the energy (ATP and NADPH) released by the light reactions. The end product, glucose, can be stored as complex carbohydrates, or it can be used in various amphibolic pathways to produce other carbohydrate intermediates or amino acids. See below for details of the process

15. Light-Independent Reactions The cycle begins at the point where CO 2 is combined with a doubly phosphorylated 5-carbon acceptor molecule called ribulose-1,5-bisphosphate ( RuBP ). This process, called carbon fixation, generates a 6-carbon intermediate compound that immediately splits into two 3-carbon molecules of 3-phosphoglyceric acid (PGA). The subsequent steps use the ATP and NADPH generated by the photosystems to form high-energy intermediates. First, ATP adds a second phosphate to 3-PGA and produces 1,3- bisphosphoglyceric acid (BPG). Then, during the same step, NADPH contributes its hydrogen to BPG, and one high-energy phosphate is removed. These events give rise to glyceraldehyde-3- phosphate (PGAL). This molecule and its isomer dihydroxyacetone phosphate (DHAP) are key molecules in hexose synthesis leading to fructose and glucose. You may notice that this pathway is very similar to glycolysis, except that it runs in reverse (see figure above). Bringing the cycle back to regenerate RuBP requires PGAL and several steps not depicted in figure above

16. Other Mechanisms of Photosynthesis Anoxygenic Photosynthesis (Non-Oxygen Producing)

17. The oxygenic, or oxygen-releasing, photosynthesis that occurs in plants, algae, and cyanobacteria is the dominant type on the earth. Other photosynthesizers such as green and purple bacteria possess bacteriochlorophyl l , which is more versatile in capturing light. They have only a cyclic photosystem I, which routes the electrons from the photocenter to the electron carriers and back to the photosystem again . This pathway generates a relatively small amount of ATP, and it may not produce NADPH. These bacteria use H 2 , H 2 S , or elemental sulfur rather than H 2 O as a source of electrons and reducing power. As a consequence, they are anoxygenic ( non-oxygen-producing ), and many are strict anaerobe

18. Chemoautotrophs

19. Chemoautotrophs Chemoautotrophs are able to synthesize their own organic molecules from the fixation of carbon dioxide. These organisms are able to produce their own source of food, or energy. The energy required for this process comes from the oxidation of inorganic molecules such as iron, sulfur or magnesium . Chemoautotrophs are able to thrive in very harsh environments, such as deep sea vents, due to their lack of dependence on outside sources of carbon other than carbon dioxide . Chemoautotrophs include nitrogen fixing bacteria located in the soil, iron oxidizing bacteria located in the lava beds, and sulfur oxidizing bacteria located in deep sea thermal vents .

20. Chemoautotrophs Chemoautotrophs are those microbs that make their own food by chemosythesis . Chemosynthesis is a process by which some organisms, such as certain  bacteria , use chemical energy to produce carbohydrates. They are capable of utilizing inorganic compounds such as hydrogen sulfide, sulfur, ammonium, and ferrous iron as reducing agents, and synthesize organic compounds from  carbon dioxide . Chemoautotrophs are found in hostile habitats such as deep sea vents and where light cannot easily penetrate through. They include the  methanogen s,  halophile s, nitrifiers ,  thermoacidophile s , sulfur oxidizers, etc .

21. Energy Generation of Heterotrophs

22. After Sugars are made or obtained, they are the energy source of life. Breakdown of sugar(catabolism) different ways: Aerobic respiration Anaerobic respiration Fermentation Energy Generating Patterns

23. A heterotroph is defined as "an organism deriving its nutritional requirements from complex organic substances." So, humans and most animals are heterotrophs. By consuming organic matter and breaking down that matter for energy. Heterotrophs can NOT produce their own energy, and completely rely on consumption of food.

24. IN CONTRAST : An autotroph can make its own energy synthetically by using simple ingredients in its environment. A plant, using  photosynthesis , is an autotroph. Sunlight is the simple ingredient. It takes that simple ingredient and creates energy with it. If you are ever confused between the two, the prefix "auto" means "oneself", if you can't remember that just remember that  autotrophs  make their food  automatically .

25. Obligate aerobes vs. anaerobes - ­ Organisms that require a constant supply of oxygen in order to live are called obligate aerobes , ex : Mycobacterium tuberculosis . -Organisms that must live in the absence of oxygen are called obligate anaerobes (oxygen would kill them), ex : Clostridium botulinum . -Organisms that can survive with or without oxygen are called facultative anaerobes , ex : E. coli . -Anaerobes perform fermentation to release energy & aerobes perform cellular respiration to release energy.

26. Overview of the Three Main Catabolic Pathways Fermentation ANAEROBIC RESPIRATION FERMENTATION A T P A T P AEROBIC RESPIRATION CO 2 NAD H ATP CO 2 NAD H ATP NAD H CO 2 ATP FADH 2 Using organic compounds as electron acceptor Electron Transport System Electron Transport System Alcohols, acids 2 ATPs 2–36 ATPs 36–38 ATPs Maximum net yield Yields variable amount of energy Yields 2 GTPs Yields 2 ATPs CO 2 NAD H ATP NAD H FADH 2 ATP CO 2 Krebs Cycle Krebs Cycle Using O 2 as electron acceptor Using non- O 2 compound as electron acceptor (So 4 2– , NO 3 –, CO 3 2– ) Glycolysis Glycolysis Glycolysis