Elements of Microbial Nutrition, Ecology and Growth Chapter 7

1. Elements of Microbial Nutrition, Ecology and Growth Chapter 7

2. Microbial nutrition • ____________: process by which chemicals (nutrients) are acquired from environment and used by organism • ________________________: must be provided; can be in elemental or molecular form • Elements needed for life ________________ Ca Fe Na Cl Mg and some others

3. Microbial nutrition Nutrients • ____________– required in large quantities; principal roles in cell structure & metabolism • proteins, carbohydrates • ____________or trace elements – required in small amounts; involved in enzyme function & maintenance of protein structure • manganese, zinc, nickel

4. Microbial nutrition Nutrients • ____________nutrients– atom or molecule that contains a combination of atoms other than carbon and hydrogen • metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate), gases (oxygen, carbon dioxide) and water • ____________nutrients- contain ____________and ____________atoms and are usually the products of living things • methane (CH4), carbohydrates, lipids, proteins, and nucleic acids

6. Microbial nutrition

7. Microbial nutrition Chemical composition of cytoplasm • 70% water • proteins • 96% of cell is composed of 6 elements • ____________ • ____________ • ____________ • ____________ • ____________ See Table 7.2 for E. coli

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9. Microbial nutrition - 6 major elements How do organisms obtain carbon? • ____________– an organism that must obtain carbon in an organic form made by other living organisms (proteins, carbohydrates, lipids and nucleic acids) • ____________- an organism that uses CO2, an inorganic gas as its carbon source • not dependent on other living things

10. 6 major elements Nitrogen • Main reservoir is nitrogen gas (N2) • 79% of earth’s atmosphere is N2 • Nitrogen is part of the structure of proteins, DNA, RNA & ATP – these are the primary source of N for heterotrophs • Some bacteria & algae use inorganic N nutrients (NO3-, NO2-, or NH3) • Some bacteria can fix N2 • Regardless of how N enters the cell, it must be converted to NH3, the only form that can be combined with carbon to synthesis amino acids, etc.

11. 6 major elements Oxygen • O2 makes up ______% of atmosphere • essential to metabolism of many organisms • major component of carbohydrates, lipids and proteins • plays an important role in structural & enzymatic functions of cell • component of inorganic salts (sulfates, phosphates, nitrates) & water

12. 6 major elements Hydrogen • major element in all organic compounds & several inorganic ones (water, salts & gases) • gases are produced & used by microbes • roles of hydrogen • maintaining ________ • forming H bonds between molecules • serving as the source of free energy in oxidation-reduction reactions of respiration

13. 6 major elements Phosphorous • main inorganic source is phosphate (PO4-3) derived from phosphoric acid (H3PO4) found in rocks & oceanic mineral deposits • key component of ____________, essential to genetics • serves in energy transfers (ATP)

14. 6 major elements Sulfur • widely distributed in environment; rocks, sediments contain sulfate, sulfides, hydrogen sulfide gas and sulfur • essential component of some vitamins and the amino acids: methionine & cysteine • contributes to stability of proteins by forming disulfide bonds

15. Important mineral ions • Potassium • Sodium • Calcium • Magnesium • Iron

16. Growth factors • organic compounds that cannot be synthesized by an organism & must be provided as a nutrient (essential ____________ nutrient) • essential amino acids – 20 – obtained from food • vitamins

17. How microbes feed • Nutritional type is based carbon and energy sources Example: • ____________: use inorganic carbon (CO2) • Photoautotrophs – make their own energy using light (“photo”) • Chemoautotrophs – Make their own energy using chemicals rather than light

18. Prefixes Troph- food, nourishment Auto- self Hetero- other Photo- light Sapro- rotten Halo- salt Thermo- heat Psychro- cold Aero- air (O2) Suffixes: -phile to love -obe to live -troph food How microbes feed terminology examples: • Autotroph • Chemoautotroph • Halophile, thermophile • Aerobe, saprobe • Aerophile (aerophilic)

19. How microbes feed Facultative vs. obligate • ____________– organism is able to adapt to a wide range of metabolic conditions – therefore it can facultatively switch its niche, habitat, nutrition etc. • ____________or strict – has a narrow niche, habitat due to limitations in its nutrition or metabolism. Microbe can only grow under those conditions.

20.  PRINT FULL SIZE How microbes feed

21. How microbes feed examples • ____________– • Photoautotrophs – photosynthesis 6CO2 + 12H2O + light energyC6H12O6 + 6O2 + 6H2O • Chemoautotrophs – methanogens 4H2 + CO2 CH4 + 2H2O • ____________ • Chemoheterotrophs C6H12O6 + 6O2 6CO2 + 6H2O + energy

22. How microbes feed • ____________– decompose dead organisms, recycle elements, release enzymes to digest materials • ____________– utilize tissues and fluids of a living host and cause harm • parasites and saprobes can be facultative (opportunistic pathogen) or obligate

23. How microbes feed saprobes • Cannot engulf large particles of food • Substrate is digested _________ by secreted enzymes • Small molecules are transported into cell

24. How microbes feed 24

25. How microbes live Symbiosis • Means “________________________” • Organisms (____________) have close association • ____________=obligatory, both symbionts benefit • Termite gut flagellates • ____________=commensal receives benefit, symbiont (host) is neither harmed nor benefited • satellitism, commensal intestinal bacteria (normal microbial flora) • ____________= parasite benefits, host is harmed • Intestinal helminths, Rickettsia, all viruses

26. How microbes live Non-symbiotic microbial associations • organisms are free-living; relationships not required for survival • ____________– members cooperate and share nutrients • ____________– some members are inhibited or destroyed by others

27. Ecological Associations Among Microorganisms 27

28. Interrelationships Between Microbes and Humans Human body is a rich habitat for symbiotic bacteria, fungi, and a few protozoa - normal microbial ____________ Commensal, parasitic, and synergistic relationships 28

29. Microbial Biofilms ____________result when organisms attach to a substrate by some form of extracellular matrix that binds them together in complex organized layers Dominate the structure of most natural environments on earth Communicate and cooperate in the formation and function of biofilms – quorum sensing 29

30. Figure 7.13 30

31. How do microbes get their nutrients??What are the transport mechanisms used to import nutrients and export waste? REMEMBER: Transport occurs across the ________________________…even in microbes with cell walls, all that is going in or coming out must cross the cell membrane

32. transport mechanisms • ____________– require no energy input from cell (uses laws of physics, like entropy) • ____________– require energy input from cell

33. Transport mechanisms • Passive transport –do not require energy, substances exist in a gradient and move from areas of higher concentration towards areas of lower concentration • ____________ • ____________– diffusion of water • ________________________– requires a carrier

34. concentration • Amount solute/solvent • Solute can be solid, liquid, gas • Solvent is usually liquid • Percentage = ________________________ • Examples: 3% NaCl = 3 g in 100 mL = 0.3 g/L • Molarity = ________________________ • Examples: 1 M NaCl solution, 10 M glucose solution etc. • Tonicity: ____________> ____________in terms of amount of solute. ____________means both solutions have the same amount of solute. • Examples: • 10% NaCl is more hypertonic than 1% NaCl • 1 M glucose is more hypotonic than 5 M glucose

35. diffusion • Molecules move along gradient: • High  low concentration • Due to RANDOM motion – increased by heat (entropy) • Evidence: Brownian movement

36. Passive transport Diffusion in cells • Small, nonpolar molecules can diffuse across cell membrane (oxygen, small lipids) • Polar molecules – ____________ ________________________ (facilitated diffusion – still PASSIVE transport – using energy of gradient)

37. Passive transport Facilitated diffusion • Carrier proteins embedded in membrane • Specific for a single type of molecule • Saturation can occur (all binding sites on carrier proteins are occupied by molecule being transported) • Competition – similar molecules can compete for binding sites – one with higher affinity (or concentration) will win and be transported

38. Facilitated diffusion 38

39. osmosis • ________________________________________________(therefore SOLUTE cannot diffuse – so water moves instead) • WATER moves from High  low water conc. (essentially, water moves from low SOLUTE to high SOLUTE) • Water moves from ______________________________ • ______________________________ Passive transport

41. Passive transport Tonicity and osmosis • ____________– low solute (high water) – has LOW osmotic potential (LOW osmotic pressure). PURE WATER is the most hypotonic • ____________– high solute (low water) – has HIGH osmotic potential (pressure). Concentrated solutions (salt and sugar preservatives) are highly hypertonic.

43. Passive transport Adaptations to osmotic effects • In a hypotonic environment: • Bacteria, algae have cell walls so they won’t burst – they just become ____________. • Amoebas, ciliates have contractile vacuoles constantly pumping water OUT • In a hypertonic environment: • Halobacteria actually absorb salt to try and stay isotonic so they won’t LOSE water (ex. Dead sea, Great Salt Lake)

44. Transport mechanisms • ____________transport – requires ____________ and carrier proteins, gradient ____________ • Examples: against gradient, faster than diffusion, large, charged molecules that can’t go through membrane –all require energy • Carrier-mediated active transport (permeases/ pumps) • Group translocation – transported molecule chemically altered • Bulk transport – ______________________ ______________________________________

45. Carrier mediated active transport Group translocation See Na/K pump movie 45

46. Bulk transport (________________) – involves vacuole/vessicle formation Active transport Liquids, solutions apicomplexans Large particles, whole cells Amoeba 46

47. Active transport

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49. MICROBIAL GROWTH

50. Microbial growth • Environmental influences on growth • Biology – stages of growth