Web Microbiology at ACM

Chapter 3, Episode 5

This episode explains how clinical laboratories identify microbes using a stepwise, evidence-based approach, combining culture, staining, biochemical tests, and molecular methods. You’ll see how rapid, accurate identification guides treatment decisions and why no single test is sufficient on its own.

Chapter 3, Episode 4

This episode covers how microscopes and stains allow microbiologists to visualize and interpret microorganisms, emphasizing magnification, resolution, and contrast. You’ll learn when light vs. electron microscopy is used and how staining techniques, especially the Gram stain, provide critical diagnostic information.

Chapter 3, Episode 3

This episode focuses on isolation as a foundational microbiology skill, explaining why pure (axenic) cultures are essential for accurate identification. You’ll learn how streak plates, spread plates, and pour plates physically separate microbes and why contamination and mixed cultures complicate interpretation.

Chapter 3, Episode 2

This episode explores culture media as diagnostic tools, explaining how media are classified by physical state, chemical composition, and function (general-purpose, enriched, selective, and differential). You’ll learn how microbiologists choose media to encourage growth, suppress competitors, and reveal metabolic traits critical for identification. 

Chapter 3, Episode 1

This episode introduces the "Five I's;" Inoculation, Incubation, Isolation, Inspection, and Identification, and explains how they provide a logical framework for working with microorganisms in both teaching and clinical labs. You’ll learn how these steps guide everything from culturing microbes to making reliable identifications.

"The Five I's" created by Marjorie Cowan, 2024

Chapter 9, Episode 39

This episode covers bacterial reproduction through binary fission, generation time and exponential growth, and the phases of the microbial growth curve. It also introduces methods for measuring population size, including turbidity measurements, direct cell counts, and viable plate counts (CFU).

Chapter 9, Episode 38

This episode introduces symbiotic relationships, including mutualism, commensalism, parasitism, and antagonism. It also covers microbial interactions within communities, with emphasis on biofilms, polymicrobial environments, and quorum sensing as a mechanism for communication and coordinated behavior.

Chapter 9, Episode 37

This episode focuses on environmental factors that influence microbial growth, including temperature classifications, oxygen requirements, and pH preferences. It also introduces reactive oxygen species and detoxifying enzymes, osmotic and pressure conditions, and the impact of these factors on microbial survival and distribution.

Chapter 9, Episode 36

This episode covers how microbes are classified based on carbon sources (autotrophs vs. heterotrophs) and energy sources (phototrophs vs. chemotrophs). It introduces combined nutritional categories, growth factors, and the role of the cell membrane in nutrient uptake, including transport mechanisms such as diffusion, facilitated diffusion, active transport, and group translocation.

Chapter 9, Episode 35

This episode introduces the chemical requirements for microbial growth, including essential nutrients (CHONPS) and the distinction between macronutrients and micronutrients. It also covers the composition of the cytoplasm as a solution, water movement through osmosis (hypotonic, isotonic, hypertonic conditions), and basic mechanisms cells use to maintain internal balance under osmotic stress.