23 Questions
What is the purpose of capsule staining in microbiology?
To detect the presence of capsules that protect bacteria
Which stain is used to observe capsules in the capsule staining process?
Congo Red
What does a clear halo around bacterial cells indicate in capsule staining?
Absence of capsules
How does capsule staining contribute to a bacteriologist's understanding of bacterial morphology?
By distinguishing encapsulated and non-encapsulated bacteria
Which type of bacteria is likely to have a slimy or mucoid appearance due to the presence of capsules?
Encapsulated bacteria
What distinguishes capsule staining from flagella staining in microbiology?
The observation of specific bacterial structures
Why is heat fixation not recommended in the preparation of a bacterial smear for capsule staining?
To avoid denaturing the gelatinous outer layer of cells
What is the role of crystal violet stain in capsule staining?
To stain bacterial cells but not the capsules
How can capsule staining be useful in differentiating between pathogenic and non-pathogenic bacteria?
By indicating the presence of capsules.
Match the following components of culture media with their descriptions:
Meat extract = Contains amino acids, vitamins, and mineral salts Yeast extract = Stimulates the growth of bacteria Peptones = Hydrolyzed animal/plant protein with nitrogen and amino acids Salts = Includes Mg, K, Fe, Ca for bacterial enzyme activity
Match the following thermal requirements with their temperature ranges:
Psychrophilic = Grows below 10 degrees Celsius Mesophilic = Grows at 20-40 degrees Celsius Thermophilic = Grows at 50-55 degrees Celsius pH REQUIREMENTS = Match the following pH categories with their descriptions:
Match the following pH categories with their descriptions:
Acidophiles = Thrive under highly acidic conditions Neutrophiles = Grow optimally at a pH between 5 and 8 Alkaliphiles/Basophiles = Grow optimally at pH values above 9
Match the physical state/consistency of culture media with their descriptions:
Liquid (no solidifying agent) = Example: Broth Agarose = Inner polysaccharide of seaweed/marine algae used as a solidifying agent Water = Essential for bacterial growth and can be distilled water Thermal Requirements = Matching temperature ranges with bacterial growth
Match the following terms with their corresponding description:
Semisolid media = Exhibits gelatinous consistency and contains 0.5 to 1% agar Enrichment media = Usually a broth that enhances the growth of an organism Selective media = Selects for the growth of a particular organism while inhibiting others through inhibitors Differential media = Provides distinct colonial appearance of microorganisms to aid in their identification
Match the following composition types with their definitions:
Synthetic/Chemically-defined media = Exact composition is known and defined chemically Complex/Non-synthetic media = Contains at least one composition which is not chemically defined Tissue culture media = Used for organisms that cannot grow in cell-free media Selective-Differential media = Allows certain types of organisms to grow and differentiate while inhibiting others
Match the following cell lines with their corresponding species or origin:
Mccoy cell = Mouse cell-like Vero cell = African green monkey A549 cell = Lung carcinoma Hela cell = Cervical carcinoma
Match the following physical forms of media distribution with their descriptions:
Plated solid media = Dispensed in petri dishes as solid media Tubed media = Dispensed in test tubes, can be liquid or solid Liquid enrichment media = Usually a broth that enhances organism growth Solid selective-differential media = Allows certain organisms to grow and differentiate while inhibiting others
Match the following terms with their correct meaning:
Vivo = Research done on a living organism Vitro = Research done in a laboratory dish or test tube Carbon = Required for cellular constituents Salt = An essential nutrient for microbial growth
Match the following microbial growth requirements with their correct functions:
Nitrogen = Needed for proteins and nucleic acids Minerals = Provide essential nutrients for growth Growth Factors = Key compounds to support cell growth Water/Moisture = Essential for maintaining cellular hydration
Match the following bacterial characteristics with their correct staining technique:
Peritrichous bacteria = Negative staining technique Monotrichous bacteria = Negative staining technique Ampitrichous bacteria = Negative staining technique Natasha Natividad = Negative staining technique
Match the following dyes with their suitable staining techniques:
Toluidine blue O and malachite green = Basic dyes used in negative staining India Ink or Nigrosin = Acidic stain utilized in negative staining Crystal violet = Basic stain for capsule staining Safranin = Counterstain in Gram staining
Match the following bacterial species with their motility characteristics:
B.cereus, S.typhi, E.coli, B.subtilis, Klebsiella = Peritrichous bacteria V.cholerae, Campylobacter spp. = Monotrichous bacteria C.jejuni, P.aeruginosa = Except Monotrichous bacteria C.jejuni, P.aeruginosa, Natasha Natividad = Ampitrichous bacteria
Match the following advantages with the corresponding staining technique:
No need to heat fix, Some bacterial spp. are resistant to basic stains = Advantages of negative staining Gives easily visible unstained cells against black colored background, Simple and quick process = Advantages of negative staining Enhances contrast between different structures of bacterial cells = Advantages of Gram staining Allows differentiation between pathogenic and non-pathogenic bacteria based on cell wall composition = Advantages of Gram staining
Study Notes
Staining Techniques
- Negative staining: uses acidic stain (India Ink or Nigrosin) that releases a hydrogen ion, causing the dye's chromophore to become negatively charged, which is repelled by the negatively charged surface of most bacterial cells.
- Advantages of negative staining: no need to heat fix, useful for bacterial spp. resistant to basic stains, and provides an easily visible unstained cell against a black background.
Flagella Staining
- Ziehl's carbol fuchsin is commonly used for flagella staining.
- Carbol fuchsin is a mixture of basic fuchsin and phenol, which has a great affinity towards the mycolic acids found in the cell membrane of bacteria.
- It also contains tannic acid and potassium alum, which coat and thicken the flagellum to make it visible.
Metachromatic Staining
- Albert stain is made up of toluidine blue O and malachite green, both of which are basic dyes.
- Toluidine blue O stains volutin granules, while malachite green stains the cytoplasm blue-green.
- Adding Albert's iodine causes the metachromatic property to be lost, and the granules appear blue-black in color.
Capsule Staining
- Capsules are gelatinous outer layers composed of polysaccharides or polypeptides secreted by bacterial cells.
- Capsules protect bacteria from phagocytosis and make colonies appear slimy or mucoid.
- Capsule staining uses Congo red as the primary stain, followed by crystal violet as the counterstain.
Microbial Growth
- Nutritional requirements: carbon, nitrogen, minerals, salt, growth factors, and water/moisture.
- Vivo: research done on a living organism.
- Vitro: research done in a laboratory dish or test tube.
Culture Media
- Components: meat extract, yeast extract, peptones, salts, agarose, and water.
- Thermal requirements: psychrophilic (below 10°C), mesophilic (20-40°C), and thermophilic (50-55°C).
- pH requirements: acidophiles (highly acidic), neutrophiles (pH 5-8), and alkaliphiles/basophiles (pH above 9).
Classification of Culture Media
- According to physical state/consistency: liquid, semisolid, and solid.
- According to composition: synthetic/chemically defined, complex/non-synthetic, and selective.
- According to dispensing/distribution: plated solid media, tubed media, and selective-differential.
- According to function and use: supportive/general purpose, selective, and differential media.
Bacterial Morphology
- Peritrichous bacteria: Bacillus cereus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Klebsiella.
- Monotrichous bacteria: Vibrio cholerae, Campylobacter spp. (except C. jejuni).
- Ampitrichous bacteria: C. jejuni.
Test your knowledge on staining techniques with a focus on negative staining methods. Identify bacteria types and staining components such as toluidine blue O and malachite green. Explore the process of negative staining using acidic stains like India Ink or Nigrosin.
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