Oxygen not required or may even be toxic to microbeMICROBIOLOGY OUTLINE:Exam 2CHAPTER SEVEN (all): Microbial Nutrition and Growth I. Microbial Nutrition- Elements- Major bioelements= C, H, N, O, P, S- Minor bioelements= Ca, Na, K, Cl, Fe- Micronutrients= Mn, Zn, Cu, others (metals) used for a few types ofchemical reactions; too much of these can be toxic- Molecules- Organic Biomolecules Types1.) Proteins2.) Carbohydrates3.) Lipids4.) Nucleic Acids Many are macromolecules Synthesized from smaller inorganic or small organic molecules Growth Factors organic molecule that cannot be synthesized andmust be taken into the cell from the environment**Vitamins are growth factors- Vitamin A you can’t synthesize; must get it from dietII. How do Microbes Acquire Nutrients?- Transport across cell membrane- Small inorganic and organic molecules Salt (ions), simple sugars, amino acids (Ca, Na, K) Carbon dioxide- Most bacteria and Fungi, many protozoa transport across cell membrane- Acquiring Nutrients from large Molecules- Bacteria and Fungi, and some protozoa secrete enzyme outside of cell (degredative enzyme) enzyme breaks down large molecule into smaller molecules of nutrients that can be transported across membrane- Phagocytosis and Injection- Some Protozoa** Particle or liquid sits in vesicle until digested once degraded into smaller particles vesicle releases the particles Pinocytosis= engulfing liquid Phagocytosis= engulfing particlesIII. Metabolic Categories- Autotroph = a microorganism that requires only inorganic nutrients and whose sole source of carbon is carbon dioxide- “Self-feeder”- Use CO2- Heterotroph = an organism that relies upon organic compounds for its carbon and energy needs- “Other feeder”- Use organic materials to get CO2- Photoautotroph = an organism that utilizes light for its energy and carbon dioxide chiefly for its carbon needs- Chemoautotroph = an organism that relies upon inorganic chemicals for its energy and carbon dioxide for its carbon (also called a chemolithotroph)- Chemoheterotroph = Microorganisms that derive their nutritional needs from organic compoundsIV. Types of Chemoautotrophs1.) Predators actively capture food- some protozoa, few bacteria and fungi; usually takes place in soil2.) Saprobes decomposers; grow on dead material- (saphoritic)3.) Commensals use living organisms to get food cell- bacteria, protozoa, fungi4.) Parasites harms organisms they are growing on or in ( pathogens)- bacteria, fungi, protozoa, virusesV. Bacterial Growth- Microbiologists measure the growth of a population- Types of growth:1.) Open system : system where some microbe has unlimited space to grow, unlimited nutrients, no build up of waste products2.) Closed system : limited space, limited nutrients, waste product build upVI. Method of Reproduction- Binary Fission bacteria splits to reproduceVII. Growth in Open System- Doubling or exponential growth- 1-2-4-8-16-32- Doubling time (generation time)= time required for the population to double in sizeVIII. Growth in Closed System- standard/normal growth curve1.) Lag phase = “gearing up” phase2.) Exponential Growth Phase = doubling growth3.) Stationary Phase = where cells start to die4.) Death Phase = more cells dyingIX. Methods of Enumeration1.) Standard Plate Count - Colony forming units2.) Turbidity - way of estimating growth in a liquid- the more bacteria there are in a flask, the cloudier the water is (more turbid)- Spectroturtometer= instrument that measures the turbidity of liquids3.) Direct Count Microscopy - look under microscope- count number of cells on grid4.) Flow Cytometry - look at how many cells by way of an electric detector hooked up to a computer; used a lot in hospitals (can count blood cells)X. Factors Influencing Growth- Nutrient limitation, waste accumulation, physical space- Other physical and chemical forces- temperature- oxygen levels- hydrogen ions (pH)- Osmotic Forces (salt concentration)- growth response- microbes grow best (optimum growth) at one point of an environmental factorXI. Temperatures Effects on Growth- Enzymes chemical reactions in body- effects rate of catalysis higher temperature higher rate (twice as fast per 10 degrees C) - high temperatures will eventually degrade proteins and enzymesXII. Membrane Fluidity: how easily molecules move around in membrane- The higher the temperature the lower the fluidity- High temperatures melt/disintegrate membraneXIII. Temperature Ranges for Microbial Growth- 0 degrees C= freezing point of water; 100 degrees C= boiling point of water- Categories of Microbial Growth1.) Psychrophile “cold loving” have optimum growth at very cold levelso Best around 4 degrees C2.) Mesophile “mid-temperature loving” have optimum growth at mid temperatureso Best around 37 degrees C= human body temp3.) Thermophile “hot loving”o Best around 65-70 degrees C4.) Hypothermophile “extreme heat loving” optimum growth at very hot temperatureso Best around the boiling point of water; 100 degrees C- Chlamydomonas nivalis= a Eukaryotic psychrophile; protozoaXIV. Oxygen’s Effects of Microbial Growth- Oxygen is needed for energy metabolism (cellular respiration) by some microbes- Must be able to deal with toxic 02 derivatives Super oxides, peroxides, others- Have enzymes to remove toxic derivatives Superoxide dismutase Catalae and peroxidase- Other microbes use alternate energy pathways that do not require oxygen (fermentation and anaerobic respiration)- Oxygen not required or may even be toxic to microbe- Lack of dismutase and catalase enzymesXV. Determining Oxygen Requirement- High 02 at the top of tube and no 02 at the bottom of the tube see where bacteria growth occurs in the liquid= oxygen preference- Study FIGURE1.) Obligate Aerobe likes high 02 levels; atmospheric levels2.) Faculative Anaerobe can grown without 02 but grows very well with high 023.) Aerotolerant Anaerobe can grown without 02 but no preference for particular level4.) Strict Anaerobe needs reduced to no 02 to growXVI. Other Environmental Factors Influencing Growth- Hydrogen ion concentration (pH)1.) Alkaphile alkaline or basic conditions2.) Acidophiles acidic conditions- Salts- Halophiles grow at 15-22% salt concentration- Normal salt concentration = 0.9% concentration for microbial growth- Pressure- Barophile
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