Microbiology Lab Techniques: Fermentation

Microbiology Laboratory Techniques

• Durham tubes are used to detect gas production during fermentation.

Indicator Dyes

• Phenol red is a pH indicator used to detect acid production during fermentation, which changes the color of the medium from red to yellow.

Carbohydrate Fermentation

• The following sugars were tested: glucose, lactose, sucrose, and fructose.

Types of Fermentation

• Homolactic fermentation is a type of fermentation that produces lactic acid as the only product.
• Heterolactic fermentation is a type of fermentation that produces lactic acid and other products, such as ethanol and carbon dioxide.

Non-Fermenters

• In broths set with non-fermenters, there will be no gas production, acid production, or color change.

Fungi Characteristics

• Fungi belong to the kingdom Fungi.
• They are eukaryotes, meaning their cells have a true nucleus.
• Fungi are heterotrophic, meaning they cannot photosynthesize.

Fungal Morphology

• Dimorphic, as it applies to fungi, means that they can exist in two different forms, such as yeast and mold.
• Hyphae are long, branching filaments that make up the mycelium.
• Mycelium is the vegetative part of the fungus, consisting of a mass of hyphae.

Fungal Reproduction

• Fungi can reproduce by producing spores, which are similar to the seeds of plants.

Week 1: Laboratory Safety and Microbiology

• Know lab syllabus and safety contract
• Location of safety equipment
• Handwashing experiment (Ex 25): C/C transient and resident microbes
• Incubation conditions: standard condition of incubation for bacterial cultures
• Fomites: Ex 4 Microbes are Everywhere
• Alpha, beta, and gamma hemolysis
• Modes of transmission: at least 4 modes
• Review questions: 1,2,4,5 / 1,2 / 2,3,4

Week 2: Microscope and Aseptic Technique

• Microscope parts and usage
• Proper microscope usage
• Microscope put away checklist
• Shapes and arrangements of bacteria
• Aseptic technique
• Flaming sterilization of loop
• Broth, slant, and deep: purpose of flaming test tube openings
• Pure culture definition
• Review questions: 1,3,4,5,6 / 2,3 / 1,2,3,4

Week 3: Smear, Gram Stain, and Negative Stain

• Good quality smear characteristics
• Basic and acidic stains: definition and examples
• Heat fixation purpose
• Unstained cells characteristics
• Gram stain procedure
• Stains used in Gram stain
• Interpretation of Gram stain results
• Negative stain procedure
• Stain used in negative stain
• Charge of negative stain
• Usage of negative stain
• Observation of negative stain
• Review questions: 1,2,5 / 1,2,3,4 / 1,2

Week 4: Acid Fast Stain and Endospore Stain

• Acid fast stain procedure
• Stains used in acid fast stain
• Steam usage in acid fast stain
• Interpretation of acid fast stain results
• Endospore stain procedure
• Stains used in endospore stain
• Steam usage in endospore stain
• Interpretation of endospore stain results
• Review questions: 1,2,3,4 / 1,2,3,4 / 2,4

Week 5: Fungi and Protozoa

• Fungi kingdom: characteristics (eukaryotic, non-photosynthetic)
• Dimorphic fungi: definition and examples
• Hyphae and mycelium: definition and function
• Fungi reproduction methods
• Rhizopus, Penicillium, Aspergillus, Candida slides: recognition and characteristics
• Diseases caused by each fungus
• Protozoa kingdom: characteristics (eukaryotic)
• Multicellular form possibility
• 7 Protozoa slides: recognition and characteristics (Trypanozoma cruzi, Trypanosoma brucei, Trichomonas, Leishmania, Giardia, Balantidium, Plasmodium, Toxoplasma)
• Diseases caused by each Protozoa
• Review questions: 1,4 / 2,5 / 2 / 1

Week 5: Fermentation Tests

• Fermentation products
• Media used in fermentation tests
• Phenol red: pH indicator (below 6.8)
• Fermentation definition
• Catabolic reactions: definition and function
• Durham tubes purpose
• Phenol red purpose
• Sugars tested in fermentation
• Homolactic and heterolactic fermentation: definitions and examples