Chapter 6 Bacterial Growth - Microbiology Lecture Slides PDF

Chapter 6: Bacterial Growth, Nutrition, and Differentiation  CHAPTER OBJECTIVES EXPLAIN HOW NUTRITION AND OTHER ENVIRONMENTAL FACTORS CAN IMPACT MICROBIAL GROWTH AND DIFFERENTIATION. Cell Biology of DISCUSS...

Chapter 6: Bacterial Growth, Nutrition, and Differentiation  CHAPTER OBJECTIVES EXPLAIN HOW NUTRITION AND OTHER ENVIRONMENTAL FACTORS CAN IMPACT MICROBIAL GROWTH AND DIFFERENTIATION. Cell Biology of DISCUSS MICROBIAL CLASSIFICATIONS BASED ON NUTRITIONAL NEEDS AND Bacteria and ENVIRONMENTAL LIMITS. Eukaryotes DESCRIBE HOW UNDERSTANDING MICROBIAL GROWTH HELPS IDENTIFY DISEASE-CAUSING PATHOGENS. DISCUSS BIOFILMS AND THEIR IMPORTANCE TO INFECTIOUS DISEASES.  SECTION OBJECTIVES EXPLAIN HOW PURE CULTURES ARE OBTAINED AND WHY THEY ARE IMPORTANT IN MEDICINE. DISTINGUISH AMONG SYNTHETIC, COMPLEX, SELECTIVE, AND DIFFERENTIAL 6.1 Culturing and MEDIA AND THEIR USE IN CLINICAL MICROBIOLOGY. Counting Bacteria DESCRIBE THE VARIOUS WAYS BACTERIAL GROWTH IS MEASURED, AND EXPLAIN THE ADVANTAGES AND DISADVANTAGES OF EACH METHOD.  6.2 Culturing and Counting Bacteria Growing Bacteria in Culture ►Culture ►Growing bacteria in culture: ► Nutrition ► Solid, liquid, or semi-solid ► Growth temperature ► pH, pressure, and osmotic balance ► Oxygen or other gases  6.2 Culturing and Counting Bacteria Solid Media Bacterial cells form colonies on solid media with agar added to make a firm surface. Streak plate method allows for separation of colonies into pure cultures.  6.2 Culturing and Counting Bacteria Selective Media Differential Media Example: MacConkey Agar Selective agents - bile salts and crystal violet Differential agent – lactose.  6.2 Culturing and Counting Bacteria Determining the Number of Cells (Dead or Alive) ► Direct Cell Counts ► Indirect Cell Counts 6.2 Culturing and Counting Bacteria Viable Cell Counts ► Serial dilution and spread plate method  Case History: Urine Cultures (Where Numbers Count) Melissa, a 25-year-old woman, visited her doctor’s office complaining of a terrible burning sensation while urinating. The physician assistant (PA) suspected the patient was suffering from a urinary tract infection (UTI) in her bladder and sent a sample of urine to the laboratory. The laboratory technician took a very small but exact volume of urine and spread it onto agar medium. After 24 hours of incubation, the clinical microbiologist found large numbers of E. coli colonies (a Gram-negative bacillus), equivalent to 100,000 bacteria per milliliter of the patient’s urine. Because urine samples from healthy patients usually have fewer than 10,000 bacteria per milliliter, the PA determined that the woman did have a UTI and prescribed an antibiotic appropriate for the etiologic (causative) agent, uropathogenic E. coli.  SECTION OBJECTIVES UNDERSTAND THE PHASES OF A TYPICAL BACTERIAL GROWTH CURVE. 6.2 The Growth EXPLAIN HOW BACTERIAL GROWTH Cycle CORRELATES TO DISEASE. DESCRIBE THE PURPOSE OF CONTINUOUS CULTURE AND HOW IT CORRELATES TO THE HUMAN DIGESTIVE TRACT.  6.3 The Growth Cycle ► Growth rate is a measure of the number of cells in a population over time. Symmetrical binary fission ► Binary fission ► Symmetrical vs asymmetrical division Asymmetrical binary fission 6.3 The Growth Cycle Bacterial Growth Curve, showing the change in growth rate over time https://www.youtube.com/watch?v=SuvGpMevLPU&t=12s 6.3 The Growth Cycle Exponential Growth (Log Phase) ► Population size doubles at a fixed rate ► Plotting growth results in exponential curve ► Generation time or doubling time varies with type of organism, medium, environmental factors ► Starting with any number of organisms at time zero (N0), the number of organisms after n generations will be N0 × 2n. Quick Question: E. coli has a generation time of 20 minutes. How many cells will there be in a culture that begins with a  SECTION OBJECTIVES DESCRIBE HOW ENVIRONMENTAL CHANGES CAN ALTER THE SHAPE OF A GROWTH CURVE. 6.4 Environmental LIST DIFFERENT CLASSES OF Limits on Microbial MICROBES BASED ON THEIR PREFERRED ENVIRONMENTAL Growth NICHES (PH, TEMPERATURE, AND SALT). IDENTIFY THE BIOLOGICAL PROPERTIES THAT ALLOW DIFFERENT CLASSES OF MICROBES TO GROW IN EXTREME ENVIRONMENTS. 6.4 Environmental Limits on Microbial Growth Growth Considerations: ► Temperature ► Pressure ► Osmotic balance ► pH level ► Nutrients ► Extremophiles  6.4 Environmental Limits on Microbial Growth Temperature Psychrophiles Mesophiles Thermophiles Hyperthermophiles  6.4 Environmental Limits on Microbial Growth Barometric Pressure ► Barophiles survive at very high barometric pressure  6.4 Environmental Limits on Microbial Growth Osmotic Pressure ► Halophiles ► All known halophiles are Archaea.  6.4 Environmental Limits on Microbial Growth pH Neutralophiles Most human pathogens Acidophiles Alkaliphiles  SECTION OBJECTIVES DIFFERENTIATE ANAEROBES FROM AEROBES AND DESCRIBE HOW EACH ARE CULTURED. 6.5 Living with EXPLAIN HOW BOTH AEROBES AND ANAEROBES CAN CAUSE Oxygen DISEASE. DISCUSS THE BASIC DIFFERENCES BETWEEN RESPIRATION AND FERMENTATION AND HOW THIS IMPACTS WHERE AN ORGANISM GROWS.  6.5 Living with Oxygen: Aerobe vs. Anaerobe ► Aerobes ► Anaerobes ► Strict Aerobes ► Strict Anaerobes  6.5 Living with Oxygen: Aerobe vs. Anaerobe ► Microaerophiles ► Aerotolerant Anaerobes ► Facultative Anaerobes 6.5 Living with Oxygen: Aerobe vs. Anaerobe  SECTION OBJECTIVES DISCUSS HOW BIOFILMS DEVELOP AND THE ROLE OF 6.6 Microbial QUORUM SENSING IN THE PROCESS. Communities and Cell Differentiation EXPLAIN THE IMPORTANCE OF BIOFILMS TO INFECTION. DESCRIBE THE PROCESS OF SPORULATION, AND EXPLAIN HOW SPORES IMPACT CERTAIN INFECTIONS.  6.6 Microbial Communities and Cell Differentiation Biofilms ► Surface-attached communities ► Single or multiple species ► Dental plaques ► Pseudomonas aeruginosa ► Staphylococci  6.6 Microbial Communities and Cell Differentiation Cells communicate and coordinate actions through quorum sensing.  6.6 Microbial Communities and Cell Differentiation Endospores ► Some Gram-positive bacteria ► Dormant ► Examples: ► Bacillus, such as B. anthracis ► Clostridium, such as C. botulinum and C. tetani ► Last for decades or centuries