3 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)
5 Sources of Nutrients Carbon – CO2 in air and rocks organisms Nitrogen – N2 in air, NO2, NO3, NH4 in soil and water organisms (NH3)Oxygen – O2 in air, inorganic salts SO4, PO4, NO3, H2OHydrogen – Water, Organic compounds in organismsPhosphorus – Rocks and minerals organismsSulfur – Rocks and minerals organisms
6 Microbe Nutritional Types Autotrophs – “Self feeder”Photoautotrophs – Photosynthetic (energy from light)Chemoautotrophs – Energy from simple inorganic chemicalsMethanogens – Metabolize H2 and CO2 into CH4 and H2OHeterotrophs – “Other feeder”Chemoheterotroph – Obtain carbon and energy from organic compounds. CnH2nOn + O2 CO2 + H2O + ATP (Adenosine tri-phosphate)Saprobe – Free living organisms that feed on dead organismsParasite – Derive nutrients from the tissues of hosts.
7 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
8 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
9 Microbial Clean-Up: In 1991, the area was surveyed and found to be mostly cleared of oil, with no further treatment recommended
11 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 membraneActive 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 membranePinocytosis – Engulfing of liquids by the cell membrane
13 Comparing SolutionsHypertonic 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 hypertonicand hypotonic solutions.)
15 How do microbes metabolize nutrients? Fermentation and Respiration
16 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 substrateSubstrate: the substance on which the enzyme actsEnzyme-substrate complex: formed when the substrate molecule collides with the active site of its enzymeEnzymes generally have a high degree of specificityEndoenzymes (intracellular)/exoenzymes (extracellular)
17 The Action of Enzymes on Substrates to Yield Products
18 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
19 Competitive Regulation and Inhibition of Enzymes
20 Noncompetitive (allosteric) inhibition of enzymes
21 Factors Influencing Enzymes TemperaturepHConcentration of substrate, product, and enzyme
22 Relationship between temperature and enzyme activity GA f08
23 Microbes and Environmental Factors TemperaturepHOxygenPressureExtremophiles – Organisms that can survive under extreme environmental conditions. An interesting source of chemical products.Interesting Website on Extremophiles and Chemical Products:
27 pH Acidophiles – grow at low pH levels. (1-2) 14 Alkaline13121110987 Neutral6543210 AcidicAcidophiles – grow at low pH levels. (1-2)Alkalinophiles – live at high pH levels. (9-10)
28 PressureBarophiles – organisms that grow at elevated pressure ( x air pressure). (Found in ocean depths often in thermal vents)
29 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 toxicFacultative anaerobes – Aerobe that can also live without O2Microaerophiles - low oxygen levels required.Aerotolerant - anaerobic metabolism, oxygen not toxic
31 Living without Oxygen….Glucose Fermentation Pathways sp08
32 Glucose Fermentation Net and practical results Cells get chemical energy (ATP)Fermentation products are natural waste products useful to humans:Fermented beveragesBreadCheeseYogurt
33 Using fermentation metabolism to identify microbes: A positive (yellow) mannitol-fermentation test. This test distinguishes the pathogenic Staphylococcus aureus(MSA)TestMannitolSaltsAgar
34 Comparing Aerobic Respiration with Anaerobic Fermentation Fermentation yields small amount of ATP (2)Partial oxidation of carbon atoms (6 C 3 C)RespirationSubstrate molecules are completely oxidized to C02 (6 C 1 C)Far higher yield of ATP (36)The Krebs Cycle and Electron Transport Chain
35 Final Electron Acceptors: Aerobic respiration, anaerobic respiration, and fermentation have different final electron acceptors
36 Microbe Growth Binary or transverse fission Generation or Doubling Time – the time required for parent cell to form two new daughter cells.
37 Microbe GrowthLag – new cells require adjustment and enlargement. The cells are not multiplying rapidly.Log or exponential – maximum rate of growth
38 Microbe Growth 2Stationary – death and multiplication balance out. Depleted nutrients and waste buildup.Death – limiting factors intensify. May last a long time.
39 Calculating Growth of Cells Nf = Final populationNi = Initial population2n = # cells in generationn = generation numberNf = (Ni)2nUse the table in the handout from the Talaro Appendix A-2 tocalculate the number of cells in the generation.
42 Measuring Growth Serial Dilutions, Plate Counts and Turbidity Measuring growth turbidity plate counts
43 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 agarSpread plate: made by adding 0.1ml of diluted culture to surface of solid medium
44 Counting colonies using a bacterial colony counter
45 Bacterial colonies viewed through the magnifying glass against a colony-counting grid
46 Countable number of colonies (30 to 300 per plate) Which of these plates would be the correct one to count? Why?GA sp08
48 Turbidity, or a cloudy appearance, is an indicator of bacterial growth in urine in the tube on the left
49 A Spectrophotometer: This instrument can be used to measure bacterial growth by determining the degree of light transmission through the culture
50 The Streak Plate Method uses agar plates to prepare pure cultures
51 A Streak Plate of Serratia marcescens A Streak Plate of Serratia marcescens. Note the greatly reduced numbers of growth /colonies in each successive region
52 Types of Culture MediaNatural Media: In nature, many species of microorganisms grow together in oceans, lakes, and soil and on living or dead organic matterSynthetic medium: A medium prepared in the laboratory from material of precise or reasonably well-defined compositionComplex 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
53 Commonly Used Media Yeast Extract Casein Hydrolysate Serum Blood agar Chocolate agar
54 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
55 Three species of Candida can be differentiated in mixed culture when grown on CHROMagar Candida plates
56 Identification of urinary tract pathogens with differential media (CHROMagar)
58 Symbiosis (Mutualism) ObligatoryBoth organisms benefit.Examples: algae + fungus = lichen, termites and trychonympha (a protist)GA sp06
59 Symbiosis (Commensalism) One organism benefits and the other is not harmed.Examples: Non-pathogenic bacteria on our skin; satellitism between bacteria colonies.
60 Symbiosis (Parasitism) One organism benefits and the other is harmed.Examples: Pathogenic organisms on their host. Plasmodium vivax a protozoan parasite causing malaria.
61 Non Symbiotic (Synergism) Substance AFree living organisms.Both benefitThe relationship is optional.Examples: Shared metabolism; nitrogen fixing bacteria in the soil and plantsMicroorganism 1Substance BMicroorganism 2Substance CMicroorganism 3End Product used by all threemicroorganisms
62 Non Symbiotic (Antagonism) Free living organismsOrganisms compete for resources.One organism secretes a substance toxic to the other.Example: Ruminal cellulose digesting bacteria and fungiGA F05