Presentation on theme: "Microbial Nutrition Gary Andersen Reference Chapter 2,5,6, 7, 8, 9 Microbiology by Tortora, Funke & Case Chemical Substances Metabolism Growth Cell."— Presentation transcript:
Microbial Nutrition Gary Andersen Reference Chapter 2,5,6, 7, 8, 9 Microbiology by Tortora, Funke & Case Chemical Substances Metabolism Growth Cell
What do microbes eat?
Composition and Nutrition of Cells 96% of cells are composed of HCNOPS. Macronutrients are nutrients required in larger quantities. (carbohydrates, proteins, fats and other CHO molecules) Micronutrients are nutrients required in trace amounts. (Mn, Zn, Cu, Ni)
Where are the Elements Used?
Sources of Nutrients Carbon – CO 2 in air and rocks organisms Nitrogen – N 2 in air, NO 2, NO 3, NH 4 in soil and water organisms (NH 3 ) Oxygen – O 2 in air, inorganic salts SO 4, PO 4, NO 3, H 2 O Hydrogen – Water, Organic compounds in organisms Phosphorus – Rocks and minerals organisms Sulfur – Rocks and minerals organisms
Microbe Nutritional Types Autotrophs – Self feeder –Photoautotrophs – Photosynthetic (energy from light) –Chemoautotrophs – Energy from simple inorganic chemicals Methanogens – Metabolize H2 and CO 2 into CH 4 and H 2 O Heterotrophs – Other feeder –Chemoheterotroph – Obtain carbon and energy from organic compounds. C n H 2n O n + O 2 CO 2 + H 2 O + ATP (Adenosine tri-phosphate) Saprobe – Free living organisms that feed on dead organisms Parasite – Derive nutrients from the tissues of hosts.
Microbial Clean-Up: The 1989 Exxon Valdez oil spill left great quantities of pooled oil on sites in the Gulf of Alaska, such as on Green Island
Microbial Clean-Up: Bioremediation in 1989, by the application of nutrients (nitrogen and phosphorus) to the shoreline accelerated the bacterial biodegradation of the oil into carbon dioxide and water
Microbial Clean-Up: In 1991, the area was surveyed and found to be mostly cleared of oil, with no further treatment recommended
How do Microbes Eat?
Transport Mechanisms Passive Transport –Diffusion – Movement of molecules from a high concentration to a low concentration. –Facilitated Diffusion- diffusion assisted by conformational change in a protein molecule. –Osmosis – Diffusion of water through a semipermeable membrane Active Transport – Moving particles against the diffusion gradient using membrane proteins and expending energy. –Endocytosis – Engulfing with cell membrane and forming a vacuole. Phagocytosis – Engulfing of cells or particles by the cell membrane Pinocytosis – Engulfing of liquids by the cell membrane
Passive Transport Osmosis animation: /westmin/science/sbi3a 1/Cells/Osmosis.htm /westmin/science/sbi3a 1/Cells/Osmosis.htm Ga f08
Comparing Solutions Hypertonic Solution – Higher solute concentration. Cells in hypertonic solutions lose water and the cell membrane shrinks away from the cell wall. (Salt on a slug) Hypotonic Solution – Lower solute concentration. Cells in hypotonic solutions take on water and swell. (Prune wrinkles of skin) Isotonic Solutions – Solutions that have reached an equilibrium with a cell or another solution. The concentration of solute is equal and the diffusion of water proceeds at equal rates. (See page 93 of text for what happens to a cell in hypertonic and hypotonic solutions.)
Animations of Passive and Active Transport logy1111/animations/transport1.htmlhttp://programs.northlandcollege.edu/biology/Bio logy1111/animations/transport1.html hill.com/olc/dl/120068/bio02.swfhttp://highered.mcgraw- hill.com/olc/dl/120068/bio02.swf
How do microbes metabolize nutrients? Fermentation and Respiration
Enzymes Provide a surface on which reactions take place Active site: the area on the enzyme surface where the enzyme forms a loose association with the substrate Substrate: the substance on which the enzyme acts Enzyme-substrate complex: formed when the substrate molecule collides with the active site of its enzyme Enzymes generally have a high degree of specificity Endoenzymes (intracellular)/exoenzymes (extracellular)
The Action of Enzymes on Substrates to Yield Products
Each substrate binds to an active site, producing an enzyme-substrate complex. The enzyme helps a chemical reaction occur, and one or more products are formed
Competitive Regulation and Inhibition of Enzymes
Noncompetitive (allosteric) inhibition of enzymes
Factors Influencing Enzymes Temperature pH Concentration of substrate, product, and enzyme
Relationship between temperature and enzyme activity GA f08
Microbes and Environmental Factors Temperature pH Oxygen Pressure Extremophiles – Organisms that can survive under extreme environmental conditions. An interesting source of chemical products. Interesting Website on Extremophiles and Chemical Products:
Temperature Classification Psychrophile Mesophile Thermophile
Temperature Thermophiles – organisms that grow at >45 degrees C. Pyrococcus fumarii is an example of a thermophile that can survive at 113 C. Thermal pool
Grand Prismatic Spring
pH Acidophiles – grow at low pH levels. (1-2) Alkalinophiles – live at high pH levels. (9- 10) 14 Alkaline Neutral Acidic
Pressure Barophiles – organisms that grow at elevated pressure ( x air pressure). (Found in ocean depths often in thermal vents)
Presence of Oxygen Aerobe – Organism able to use O2 in metabolism. Anaerobe – Organism unable to use O2 in metabolism. Obligate aerobes - oxygen mandatory Obligate anaerobes - oxygen toxic Facultative anaerobes – Aerobe that can also live without O 2 Microaerophiles - low oxygen levels required. Aerotolerant - anaerobic metabolism, oxygen not toxic
Microbial Processing of Oxygen Step 1: O O H+ H 2 O 2 + O 2 (Catalyzing enzyme is Superoxide dismutase) Step 2: H 2 O 2 + H 2 O 2 2H 2 O + O 2 (Catalyzing enzyme is Catalase)
Living without Oxygen….Glucose Fermentation Pathways sp08
Glucose Fermentation Net and practical results Cells get chemical energy (ATP) Fermentation products are natural waste products useful to humans: 1.Fermented beverages 2.Bread 3.Cheese 4.Yogurt
Using fermentation metabolism to identify microbes: A positive (yellow) mannitol-fermentation test. This test distinguishes the pathogenic Staphylococcus aureus (MSA) Test Mannitol Salts Agar
Comparing Aerobic Respiration with Anaerobic Fermentation Fermentation Fermentation yields small amount of ATP (2) Partial oxidation of carbon atoms (6 C 3 C) Respiration Substrate molecules are completely oxidized to C02 (6 C 1 C) Far higher yield of ATP (36) The Krebs Cycle and Electron Transport Chain
Final Electron Acceptors: Aerobic respiration, anaerobic respiration, and fermentation have different final electron acceptors
Microbe Growth Binary or transverse fission Generation or Doubling Time – the time required for parent cell to form two new daughter cells.
Microbe Growth Lag – new cells require adjustment and enlargement. The cells are not multiplying rapidly. Log or exponential – maximum rate of growth
Microbe Growth 2 Stationary – death and multiplication balance out. Depleted nutrients and waste buildup. Death – limiting factors intensify. May last a long time.
Calculating Growth of Cells N f = (N i )2 n N f = Final population N i = Initial population 2 n = # cells in generation n = generation number Use the table in the handout from the Talaro Appendix A-2 to calculate the number of cells in the generation.
Measuring growth turbidity plate counts Measuring Growth Serial Dilutions, Plate Counts and Turbidity
Calculation of the number of bacteria per milliliter of culture using serial dilution Pour plate: made by first adding 1.0ml of diluted culture to 9ml of molten agar Spread plate: made by adding 0.1ml of diluted culture to surface of solid medium
Counting colonies using a bacterial colony counter
Bacterial colonies viewed through the magnifying glass against a colony-counting grid
Which of these plates would be the correct one to count? Why? Countable number of colonies (30 to 300 per plate) GA sp08
The Petroff-Hausser Counting Chamber
Turbidity, or a cloudy appearance, is an indicator of bacterial growth in urine in the tube on the left
A Spectrophotometer: This instrument can be used to measure bacterial growth by determining the degree of light transmission through the culture
The Streak Plate Method uses agar plates to prepare pure cultures
A Streak Plate of Serratia marcescens. Note the greatly reduced numbers of growth /colonies in each successive region
Types of Culture Media Natural Media: In nature, many species of microorganisms grow together in oceans, lakes, and soil and on living or dead organic matter Synthetic medium: A medium prepared in the laboratory from material of precise or reasonably well- defined composition Complex medium: contains reasonably familiar material but varies slightly in chemical composition from batch to batch (e.g. peptone, a product of enzyme digestion of proteins) Ga sp08
Commonly Used Media Yeast Extract Casein Hydrolysate Serum Blood agar Chocolate agar
Selective, Differential, and Enrichment Media Selective medium: encourages growth of some organisms but suppresses growth of others (e.g. antibiotics) Differential medium: contains a constituent that causes an observable change (e.g. MacConkey agar) Enrichment medium: contains special nutrients that allow growth of a particular organism that might not otherwise be present in sufficient numbers to allow it to be isolated and identified
Three species of Candida can be differentiated in mixed culture when grown on CHROMagar Candida plates
Identification of urinary tract pathogens with differential media (CHROMagar)
Ecological Associations GA f 07
Symbiosis (Mutualism) Obligatory Both organisms benefit. Examples: algae + fungus = lichen, termites and trychonympha (a protist) GA sp06
Symbiosis (Commensalism) One organism benefits and the other is not harmed. Examples: Non- pathogenic bacteria on our skin; satellitism between bacteria colonies.
Symbiosis (Parasitism) One organism benefits and the other is harmed. Examples: Pathogenic organisms on their host. Plasmodium vivax a protozoan parasite causing malaria.
Non Symbiotic (Synergism) Free living organisms. Both benefit The relationship is optional. Examples: Shared metabolism; nitrogen fixing bacteria in the soil and plants Substance A Substance B Substance C Microorganism 1 Microorganism 2 End Product used by all three microorganisms Microorganism 3
Non Symbiotic (Antagonism) Free living organisms Organisms compete for resources. One organism secretes a substance toxic to the other. Example: Ruminal cellulose digesting bacteria and fungi GA F05