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Bacterial Requirements & Growth: Reproduction, Nutrition, and Environmental Factors

This article discusses the different methods of bacterial reproduction, nutritional requirements, and the physical and chemical factors that influence bacterial growth. It also covers the different phases of growth and the techniques used to measure microbial growth.

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Bacterial Requirements & Growth: Reproduction, Nutrition, and Environmental Factors

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  1. Bacterial Requirements Growth and Nutrition

  2. Bacterial Reproduction • Reproduction • Binary Fission • Budding • Fragmenting • Function • Increase number of cells • Genetic recombination possible • End result : Growth

  3. Binary Fission

  4. Budding versus Fission

  5. Fragmenting

  6. Generation Time • Define • Time • Reason • Requirements • Physical • Chemical • Result • Genetic recombination • Mutations

  7. Growth Curve Graph

  8. Growth Curve Labeled Phases • Lag phase • Adaptive • Start metabolism • 1-3 days • Log phase • Generation time doubles • Most metabolically active • Stationary phase • Growth = death • Death phase • Requirements decrease • Possible spore formation

  9. Growth Curve Changes due to Ab

  10. Measurement of Microbial Growth • CFU • Direct • Viable Plate Counts • Serial Dilutions • Pour Plate • Spread Plate • Membrane Filtration • Counting Chamber • MPN (fecal, H20, food) • Indirect • Turbidity • Metabolic activity

  11. Nutritional Requirements

  12. Macro and Trace Elements

  13. Carbon Oxygen Nitrogen Hydrogen Phosphorus Sulfur Main component Cell water, aerobic respiration AA, NA, coenzymes H20 Nucleotides, PL, LPS Several AA; coenzyme Nutritional Element Use

  14. Cycles

  15. Potassium Magnesium Calcium Iron Cobolt Zinc Copper Manganese Cofactors in enzymatic reactions in the cell Metal Ions and Trace Minerals

  16. Growth Factors: Vitamins involved in many Metabolic Reactions redox deamination decarboxylation transamination synthesis • Folic Acid • Biotin • Niacin • Pantothenic acid • Riboflavin [B2] • Thiamine [B1] • Pyridoxine [B6] • B12 • K

  17. Nutrient Uptake • Diffusion • Simple (passive) • Facilitated • Osmosis • Active Transport • ATP • H+ (protomotive) • Group Translocation • Alter molecule • PTS (phosphorylate)

  18. Group Translocation

  19. Membrane Transport Summary

  20. Oxygen Requirements • Obligate Aerobes • Microaerophiles • Aerotolerant aerobes • Obligate Anaerobes • Facultative Anaerobes • Capnophiles

  21. Bacterial Examples of O2 Groups • Obligate Aerobes • Pseudomonas • Microaerophiles • H. pylori • Aerotolerant aerobes • Streptococcus • Lactobacillus • Obligate Anaerobes • Clostridium • Facultative Anaerobes • E. coli • Stapylococcus • Capnophilic • Campylobacter E coli Staph

  22. Oxygen Requirement Classification

  23. Aerobic / Anaerobic Lab Tests aerobe FA aerotolerant anaerobe

  24. Oxygen Forms • Normal • Toxic • Singlet: 1-O2 with electrons in higher energy state • Superoxide radical: O2- • Peroxide Anion: O2= • Hydroxide radical: OH- from incomplete reduction of hydrogen peroxide [H2O2]

  25. Radiation • EM radiation spectrum • Source • Sun • Visible light • UV • Infrared • Radio waves • Ionizing Radiation • X rays • Gamma rays • Create ROS

  26. Enzyme Presence to Detoxify O2 - Superoxide Catalase Peroxidase • Abligate Aerobes and FA + + - • Aerotolerant Anaerobes + - + • Obligate anaerobes - - - SOD

  27. Catalase Test

  28. Physical Requirements: pH Define pH mathematically Know number range

  29. pH Groups • Acidophile • Bacillus acidocaldarius • Lactobacillus acidophilus • Neutrophile • E. coli • Staphylococcus aureus • Akaliphile • Streptococcus pneumoniae • Nitrobacter sp.

  30. Physical Requirements: Temperature • Psychrophile • Unsaturated FA in cell membrane • Cold temperatures • Psychrotroph (facultative psychrophiles) • Refrigeration • Room temperature • Mesophile • Warm Blooded Animals • Thermophile/Hyper- • Saturated FA in cell membrane

  31. Psychrotrophs and Mesophiles

  32. Bacterial Examples: Temperature psychrophile psychrotroph mold Vibrio mesophile thermophile Archaea E coli

  33. Physical Requirements: Salt • Extreme Halophile : 30 % NaCl • Obligate Halophile : 15% NaCl • Facultative Halophile : 2% NaCl • Halotolerant : NaCl not needed, can grow in low salt

  34. Extreme Halophiles Great Salt Lake

  35. Osmosis and Water Activity • Activity of water [Aw] = 1.0 for pure water • Aw for human blood = 0.99 • Range required 0.7-1.0 Aw • E.coli requires Aw of 0.91 • Stapylococcus requires Aw of 0.85

  36. Physical Effect of Water • Define osmosis • Osmotic Pressure • Tonicity • Isotonic • Hypertonic • Hypotonic • Effects • Osmotolerant • Hydrostatic Pressure • Barotolerant • Barophiles (deep ocean)

  37. Nutritional Groups • Photoautotrophs • Chemoautotrophs • Photoheterotrophs • Chemoheterotrophs • Many bacteria • Most all Eukarya • How Acquire Electrons • Organotrophs • Lithotrophs

  38. Close ecological relationship between individuals of two or more different species Mutualism Commensalism Synergism Parasitism Competition Neutralism Biofilms Symbiotic Relationships

  39. Mutualism: Both Benefit Human Eye-lash mite

  40. Bacterial Symbiosis

  41. Biofilms Slime layer Fimbria

  42. Parasitism

  43. Agar

  44. Culturing Organisms • Inoculum • Medium • Pure Culture • Sterile

  45. Cultivation Media • Chemically Defined • Complex Undefined • General Purpose • Enriched • Selective • Differential • Anaerobic

  46. Cultural Characteristics • Solid Media [Petri] • Color • Size • Shape • Elevation • Margin • Broth Media • Slant • Gelatin Liquefaction

  47. Colony Characteristics on Agar Plate

  48. Complex General Media:Nutrient (TSA) Agar agar broth slant

  49. Enriched Media BAP Chocolate agar

  50. Selective and Differential Media C-CNA MAC MSA EMB

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