Chapter 1: The Science of Microbiology (PT. 1)

Microbiology

Microbiology

study of organisms that cannot be seen in the naked eye

normal flora or indigenous flora

only produce disease in persons with compromised immune systems

Robert Hooke

discover the cell as the basic unit of life

Anton von Leeuwenhoek

• created a single lens microscope that he used to make observations of microorganisms which he called animalcules.

• Father of Microbiology

• provide accurate descriptions of bacteria, protozoa, and fungi

Louis Pasteur

• initially formulated germ theory of disease

• developed the process of pasteurization, which kills microorganisms in different types of liquid, that became the basis for aseptic techniques

• introduced the aerobes and anaerobes and developed the fermentation process

Robert Koch

• prove that microorganisms caused certain diseases through a series of scientific steps

  • prove and illustrate further about germ theory

Edward Jenner

discovered the vaccine for smallpox

Joseph Lister

applied the theory to medical procedures paving the way for the development of aseptic surgery

Paul Ehrlich

• discovered Salvarsan for the treatment of syphilis

• heralded the “magic bullet” of chemotherapy, which is treatment of disease by using chemical substances

Alexander Fleming

discovered the antibiotic penicillin from the mold Penicillium notatum.

Compound Microscope also known compound light microscope

• type of microscope that contains one magnifying lens.

• can magnify objects approximately a thousand times their original size

• Visible light is its main source of illumination

Ocular lens or eyepiece

topmost part of the microscope which is the lens the viewer looks through to see the specimen

Revolving nose piece

located above the stage, it holds the objective lenses

Diopter adjustment

It used to change focus on one eyepiece in order to correct any difference in vision between the two eyes

Body tube or head

connects the eyepiece to the objective lenses

Arm

connects the body tube to the base of the microscope

Coarse adjustment

brings the specimen into general focus

Fine adjustments

fine-tunes the focus and increases the details of the specimen

objective lenses

This is held in place above the stage by the revolving nosepiece and are the lenses that are closest to the specimen. It contains 3 to 5 objectives ranging in power from 4X to 100X.

Stage

Located beneath the revolving nosepiece, it is the flat platform on which the specimen is placed.

Stage clips

Situated above the stage, these are metal clips that hold the slide in place.

Stage control

Found beneath the stage, these knobs move the stage either left or right or forward and backward.

Aperture

The hole in the middle of the stage that allows light from the illuminator to reach the slide containing the specimen.

On/Off switch

The switch located at the base of the microscope that turns the illuminator on or off.

Illuminator

The light source of the microscope.

Iris diaphragm

Found on the condenser, it is used to adjust the amount of light coming through the condenser.

Condenser

It is found beneath the stage and contains a lens system that focuses light onto the specimen. It gathers and focuses light onto the specimen.

Base

It supports the microscope and it is where the illuminator is found.

Brightfield Microscope

• made up of a series lenses and utilizing visible light as its source of illumination

• magnify an object 1,000 to 1,500x

• visualize bacteria and fungi

• specimen appears dark against the surrounding bright viewer field of this microscope.

• very low contrast

Darkfield Microscope

• utilizes reflected light instead of transmitted light, w/ a special condenser that has an opaque disc that blocks the light.

• specimen to be studied appears brights against dark background

• ideal for studying specimens that are unstained or transparent and absorb little or no ight

• useful in examining the external details of the specimen such as its outline or surface

Phase-contrast Microscope

• contrast-enhancing optical technique in order to produce high-contrast images of specimens that are transparent which include thin tissue slices, living cells culture, and subcellular particles.

Fritz Zernike

phase-contrast microscope was first introduced by

Differential Interference Contrast Microscope

• utilizes two beams of light instead of one, has higher resolution

• useful in examining living specimens when normal biological processes might be inhibited by standard staining procedures.

George Nomarski

developed differential interference contrast microscope as an improvement to phase-contrast microscope

Fluorescence Microscope

used to visualize structural components of small specimens such as cells and to detect the viability of cell populations.

may used to visualize genetic material of the cell (DNA/RNA)

fluorochromes

fluorescent dyes

Confocal Microscope

• useful in the study of cell physiology

  • This is used, together with computers, to produce 3D image.

Modern Electron Microscope

• used to visualize viruses and subcellular structures of the cell.

• capable of magnifying objects up to 2 million times

2 types of electron Microscope

transmission electron microscope (TEM)

scanning electron microscope (SEM)

transmission electron microscope (TEM)

• produce 2D b/w images

• magnifies 200,000x

scanning electron microscope (SEM)

• relies on interactions at the surface rather than transmission

• magnify bulk samples with greater depth view

  • 3D structure of the sample black & white

  • magnify the object 10,000x

Ernst Ruska

built the first prototype of electron microscope

Scanning Probe Microscope

• used to study the molecular and atomic shapes of organisms on a nanoscale

• determine variations in temperature inside the cell as well as its chemical properties

Dr. Gerd Binnig & Dr. Heinrich Rohrer

developed scanning probe microscope

staining

this procedure are meant to give color to the organisms, making them easier to see under microscope

Simple stains

make use of single dye which can either be aqueous (water-based) or alcohol-based

method of staining is a quick and easy way to visualize cell shape, size, arrangement of bacteria.

safranin, methylene blue, or crystal violet

simple stains uses basic dyes such as?

Differential stains

used to differentiate one group bacteria from another

Gram stain

Acid-fast stain

2 types of differential staining procedures

Gram stain

distinguishes gram-positive bacteria from gram-negative bacteria