1. NUTRITION AND CULTURE OF MICROORGANISMS

2. Metabolism Catabolism Anabolism

3. Microbial nutrition Microbial nutrition is that aspect of microbial physiology that deals with the supply of monomers (or the precursors of monomers) that cells need for growth. Collectively, these required substances are called nutrients.

4. Different organisms need different complements of nutrients, and not all nutrients are required in the same amounts. Macronutrients: required in large amounts Micronutrients: required in trace amounts.

5. A microbial periodic table of the elements

7. The Common Nutrient Requirements Requirements for Carbon, Hydrogen, and Oxygen

8. The requirements for carbon, hydrogen, and oxygen often are satisfied together by organic compounds These organic nutrients are almost always reduced and have electrons that they can donate to other molecules, they also can serve as energy sources. One important carbon source that does not supply hydrogen or energy is carbon dioxide (CO 2 ). This is because CO 2 is oxidized and lacks hydrogen. Sources of Carbon, Energy and Electron

9. Use CO 2 as their sole or principal source of carbon Many microorganisms are autotrophic, and most of these carry out photosynthesis and use light as their energy source Some autotrophs oxidize inorganic molecules and derive energy from electron transfers. Autotrophs

10. Organisms that use reduced, preformed organic molecules as carbon sources are heterotrophs (these preformed molecules normally come from other organisms). Heterotrophs most heterotrophs use reduced organic compounds as sources of both carbon and energy

11. Remarkable nutritional characteristic of microorganisms Burkholderia cepacia Leptospira

12. Nutritional Types of Microorganisms Organisms are grouped based on their C, En and e - sources Based on C sources : –Autotrophs and Heterotrophs Based on Energy sources: –light energy (Phototrophs) –the energy derived from oxidizing organic or inorganic molecules (Chemotrophs) Based on electron sources: –reduced inorganic substances [Lithotrophs (i.e., “rock-eaters”) ] –electrons from organic compounds (organotrophs)

14. Four major nutritional types 1. Photolithotrophic autotrophs (often called photoautotrophs or photolithoautotrophs) use light energy and have CO 2 as their carbon source. –Eucaryotic algae and cyanobacteria employ water as the electron donor and release oxygen. –Purple and green sulfur bacteria cannot oxidize water but extract electrons from inorganic donors like hydrogen, hydrogen sulfide, and elemental sulfur

15. 2. Chemoorganotrophic heterotrophs (often called chemoheterotrophs, chemoorganoheterotrophs, or even heterotrophs) use organic compounds as sources of energy, hydrogen, electrons, and carbon Frequently the same organic nutrient will satisfy all these requirements. Essentially all pathogenic microorganisms are chemoheterotrophs

16. 3. Photoorganotrophic heterotrophs (photoorganoheterotrophs) are common inhabitants of polluted lakes and streams. Some of these bacteria also can grow as photoautotrophs with molecular hydrogen as an electron donor. Some purple and green bacteria are photosynthetic and use organic matter as their electron donor and carbon source

17. 4.Chemolithotrophic autotrophs (chemolithoautotrophs), oxidizes reduced inorganic compounds such as iron, nitrogen, or sulfur molecules to derive both energy and electrons for biosynthesis. Carbon dioxide is the carbon source A few chemolithotrophs can derive their carbon from organic sources and thus are heterotrophic Chemolithotrophs contribute greatly to the chemical transformations of elements (e.g., the conversion of ammonia to nitrate or sulfur to sulfate) that continually occur in the ecosystem

19. Many purple nonsulfur bacteria act as photoorganotrophic heterotrophs in the absence of oxygen but oxidize organic molecules and function chemotrophically at normal oxygen levels. When oxygen is low, photosynthesis and oxidative metabolism may function simultaneously. Beggiatoa that rely on inorganic energy sources and organic (or sometimes CO2) carbon sources Purple nonsulfur bacteria

20. Growth factors Many microbes can not synthesize all indispensable constituents from the essential elements but must obtain them or their precursors from the environment Organic compounds required because they are essential cell components or precursors of such components and cannot be synthesized by the organism are called growth factors

21. There are three major classes of growth factors: (1) amino acids (2) purines and pyrimidines (3) vitamins Amino acids are needed for protein synthesis, purines and pyrimidines for nucleic acid synthesis Vitamins are small organic molecules that usually make up all or part of enzyme cofactors, and only very small amounts sustain growth

22. Bacterial colonies. Colonies are visible masses of cells formed from the subsequent division of one or a few cells and can contain over a billion (109) individual cells. (a) Serratia marcescens, grown on MacConkey agar. (b) Close-up of colonies outlined in (a). (c) Pseudomonas aeruginosa, grown on Trypticase soy agar. (d) Shigella flexneri, grown on MacConkey agar

23. Aseptic transfer. (a) Loop is heated until red hot and cooled in air briefly. (b) Tube is uncapped. (c) Tip of tube is run through the flame. (d) Sample is removed on sterile loop and transferred to a sterile medium. (e) The tube is reflamed. (f) The tube is recapped. Loop is reheated before being taken out of service.

24. Method of making a streak plate to obtain pure cultures. (a) The loop is sterilized and a loopful of inoculum is removed from tube. (b) Streak is made and spread out on a sterile agar plate. Following the initial streak, subsequent streaks are made at angles to it, the loop being resterilized between streaks. (c) Appearance of a well-streaked plate after incubation. Colonies of the bacterium Micrococcus luteus on a blood agar plate. It is from such well-isolated colonies that pure cultures can usually be obtained