Introduction to Microbiology

Introduction to Microbiology

• Microbiology is the study of very small living organisms.
• Microorganisms are ubiquitous.

Etymology of Microbiology

• "Micro" refers to something very small or minute.
• "Biology" comes from "Bios," meaning living organisms, and "logy," which means the study of.

History of Microbiology

• Early Years: Discoveries and foundational knowledge were established.
• The Golden Age: Significant advancements and discoveries occurred.
• The Modern Age: Characterized by advanced technologies and deeper understanding.

Early Years of Microbiology

• Antoni van Leeuwenhoek discovered the microbial world.
• Leeuwenhoek created a simple microscope.

Golden Age of Microbiology

• Louis Pasteur found that bacteria ferment grape juice into acids, causing wine spoilage, and developed pasteurization.
• Richard Petri invented Petri dishes.
• Hans Christian Gram developed Gram's stain technique.
• Edward Jenner tested the hypothesis that a mild disease called cowpox can provide protection against potentially fatal smallpox.
• Smallpox is caused by the Variola virus.
• Alexander Fleming discovered penicillin.
• Zone of Inhibition, where Penicillium chrysogenum inhibits bacterial growth.

Wu Lien-teh

• Wu Lien-teh was a Malayan physician.
• He was renowned for his work in public health, specifically regarding the Manchurian pneumonic plague.
• He invented the "Wu mask," which was a forerunner to the N95 respirator.

Modern Age of Microbiology

• Molecular Biology combines aspects of biochemistry, cell biology, and genetics. This is used to explain cell function at the molecular level.
• Recombinant DNA Technology involves manipulating the genes of microorganisms for practical applications.

Microscope Technology

• Microscopy is the technology used to make very small things visible to the human eye.
• Anton van Leeuwenhoek (1632-1723) was the first person to see individual microorganisms.
• He constructed simple microscopes which are capable of magnifying objects 100 to 300 times.

Microscopic Examination

• Light microscopes and electron microscopes are used in microscopic examination.
• Magnification enlarges the image of an object.
• Specific lenses magnify the image of a cell, making its structural details more apparent.
• Resolution is the ability to distinguish two adjacent points as separate.

Light Microscope Components

• Body Tube
• Ocular Lens
• Nosepiece
• Arm
• Objective Lenses
• Stage
• Clips
• Coarse Adjustment
• Fine Adjustment
• Diaphragm
• Light Source
• Base

Lens Systems in Light Microscopy

• The ocular lens, also known as the eyepiece, is located at the top of the instrument.
• An ocular consists of two or more internal lenses and typically has a magnification of 10x.
• Modern microscopes often feature binocular lenses.
• Objectives: Typically, three or more objectives are attached to a rotatable nosepiece for easy positioning.
• Types of objectives:
  • Low power: 10x magnification.
  • High-dry: 40x magnification.
  • Oil immersion: 100x magnification.

Light Microscope Properties

• Ocular lenses magnify 10-15x, usually 10x.
• High-grade optical oil should be placed between the specimen and the objective for high numerical aperture/100X.
• Total magnification = magnification of objectives (10x, 40x, or 100x) multiplied by the magnification of the ocular/eyepiece (10x).

Electron Microscopes

• There are two types: TEM (Transmission Electron Microscope) and SEM (Scanning Electron Microscope).
• Samples must be frozen or embedded in plastic, therefore not living.
• TEM can magnify hundreds of thousands of times with a resolution as great as 0.2 nm.
• SEM provides a 3D image, but with lower magnification than TEM.

Cell Types

• There are two kinds of cells: Prokaryotic and Eukaryotic.
• Prokaryotic cells are structurally simpler.
• All living things are made of cells and contain similar macromolecules and cell structures.

Prokaryotes

• Prokaryotes are small and microscopic.
• They have a simple structure.
• Their genetic material is "naked" DNA, it is not protein-bound chromosomes, and lacks a nucleus.
• No organelles are present.
• The cell walls are made of peptidoglycan.
• Prokaryotic cells lack a nucleus and membrane-bound organelles.
• They contain cytoplasm bound by the plasma membrane.

Eukaryotes

• Eukaryotes are larger and can be single-celled or multicellular.
• They have a complex structure.
• Their genetic material is DNA as a complex with proteins, forming chromosomes.
• Chromosomes are contained within a nucleus.
• Membrane-bound organelles are present.
• Some have cell walls made of cellulose or chitin.
• Eukaryotic cells feature DNA in a nucleus that is bounded by a membranous nuclear envelope.
• Membrane-bound organelles are also present.
• Cytoplasm is in the region between the plasma membrane and nucleus.
• Eukaryotic cells are generally much larger compared to prokaryotic cells.

Taxonomic Hierarchy

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species
• A mnemonic is "Dear King Philip Come Over For Good Soup"

Five Kingdoms Classification

• Animalia: multicellular organisms.
• Protista: simple eukaryotes.
• Monera (Prokaryotae): all bacteria.
• Plantae: multicellular organisms that perform photosynthesis.
• Fungi: organisms that grow by spores or fermentation of hyphae.

The Five-Kingdom System of Classification

Scientific Names

• The scientific or binomial name consists of the Genus and species.
• The scientific name should always be italicized or underlined.
• The genus name begins with a capital letter.
• The species name is not capitalized.
• Scientific names can be abbreviated by using the capital letter of the genus and a period.
  • Example: M. koenigii

Uses of Scientific Names

• Describe an organism
• Honour a researcher
• Identify the habitat of a species