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Microbiology

• Is the science that studies microorganisms.
• These organisms are too small to be seen with the naked eye.
• Examples include bacteria, viruses, algae, fungi, and protozoa.

Microscopic Parts

• Head: Contains ocular lenses (eyepieces).
• Magnification power is 10x.
• Removable.
• Nose piece: A rotating circular structure that holds objective lenses.
• Allows for varying magnification.
• Objective Lenses: There are commonly 3 or 4 lenses.
• Provide different magnification powers (e.g., 4x, 10x, 40x, 100x).
• Use of oil immersion with 100x lens for increased magnification.
• Arm: Connects the base and head, providing support for handling the microscope.
• Base: The bottom part of the microscope; provides a stable support.

Stage and Stage Clips

• The part on which a slide is placed.
• Stage clips used to secure the slide.

Condenser

• A condenser lens positioned below the stage.
• Used to collect light from the illuminator.
• Focuses the light onto the specimen.

Diaphragm

• A device below the stage.
• Controls the amount of light that reaches the specimen.

Illuminator

• The light source in the microscope.
• Light switch to turn the microscope on and off.
• Brightness adjustment controls light bulb voltage.

Adjustment Knobs

• Coarse Adjustment Knob: Used for initial focusing, moves the stage up and down.
• Fine Adjustment Knob: Used for precise focusing, moves the stage very slowly.

Media (Composition)

• Is a mixture of nutrients needed for the growth of microorganisms.
• Water is an essential component required for enzyme activity.
• Tap water is not ideal for media preparation because it contains ions that may interact with other medium components.
• Distilled or sterilized water is preferred.

Carbon Sources

• These are important components in the medium.
• Include carbohydrates like glucose, sucrose, or fructose.
• Provide energy (ATP) to cells.

Nitrogen Sources

• Essential for protein synthesis.
• Organic examples include amino acids and proteins.
• Inorganic types such as NO3, NO2, and N2 are also crucial.

Minerals

• Required in both high and low amounts by microorganisms.
• Cofactors for enzymes.
• Examples: Na, K, Ca, Mg, Fe, Mn, Zn.

Types of Media

• Natural Media: Unknown composition and concentration (e.g., potato extract broth media).
• Synthetic Media: Known composition and concentration (e.g., Dox media, MYGP, starch nitrate agar media).
• Semi-synthetic Media: Partially known composition and concentration (e.g., potato dextrose agar media (PDA)).
• These media differ in their physical states (e.g., broth, solid, semisolid).

Other

• Media Sterilization: Involves killing all forms of microorganisms including vegetative cells and spores.
• Methods include chemical sterilization using substances like alcohol and phenol as well as physical sterilization techniques such as using UV radiation, dry or moist heat such as autoclave.

Types of Culture

• Pure Culture: Contains only one type of organism.
• Mixed Culture: Contains more than one type of organism.

Isolation of Microorganisms

• Isolating microorganisms from their natural habitats.

Sterilization Techniques

• Autoclaving (121°C, 1.5 atm, 20 minutes) for sterilization of media, solutions, and other materials that can withstand the heat.
• Flaming (using a Bunsen burner) for sterilizing tools like inoculation loops and forceps.
• Filters (e.g., bacterial filters) for sterilizing solutions.

Microscopy

• Using a microscope to view microorganisms and their structures.

Bacterial Cell Structure

• Capsule: Protective layer.
• Cell wall: Provides shape and support.
• Cell membrane: Regulates passage of materials; location of respiratory enzymes.
• Cytoplasm: Gel-like substance containing genetic material (nucleoid).
• Ribosomes: Involved in protein synthesis.
• Genetic material: Deoxyribonucleic acid (DNA) is the genetic material.
• Flagella: For motility.
• Pili: For attachment and DNA transfer.

Bacterial Morphology

• Cocci: Spherical.
• Bacilli: Rod shaped.
• Spirilla: Spiral shaped.
• Vibrios: Comma shaped.
• Filamentous: Thread like.

Bacterial Classification

• Gram-positive: Retain crystal violet stain.
• Gram-negative: Do not retain crystal violet stain.

Bacterial Nutrition

• Autotrophs: Produce their own food.
• Heterotrophs: Obtain food from other organisms.

Algae

• Unicellular or multicellular.
• Most are autotrophic, performing photosynthesis.
• Examples:
  • Chlamydomonas, Spirogyra, Zygnema, Volvox, Pandorina, Diatoms, Bacillarophyta, Phaeophyta, Rhodophyta.

Fungi

• Eukaryotic.
• Heterotrophic.
• Some unicellular, others filamentous.
• Examples: Rhizopus, Aspergillus, Penicillium, Saccharomyces, Agaricus.
• Reproduce either asexually or sexually.