This document discusses electron microscopy and its use to study microorganisms. It describes different types of electron microscopes, including transmission electron microscopes (TEM), scanning electron microscopes (SEM), reflection electron microscopes (REM), scanning transmission electron microscopes (STEM), and low-voltage electron microscopes (LVEM). Each type of microscope is explained in terms of its working principle and resolution. Examples are given of specific microorganisms that have been imaged using different electron microscopes, such as E. coli with TEM, Candida albicans with SEM, Aspergillus niger with REM, and plant and rat heart cells with other types. In summary, electron microscopes provide higher magnification than light

1. Electron Microscopy to
Study the Micro
Organisms

2. Electron Microscope
● The electron microscope is a type of microscope that uses
electrons to create an image of the target.
● It has much higher magnification or resolving power than a
normal light microscope.
● As the wavelength of an electron can be up to 100,000
times shorter than that of visible light photons.

3. Principle: An electron
microscope uses an 'electron
beam' to produce the image of the
object and magnification is obtained
by 'electromagnetic fields'; unlike
light or optical microscopes, in
which 'light waves' are used to
produce the image and
magnification is obtained by a
system of 'optical lenses'.

4. Types of Electron Microscopes
● Transmission electron microscope (TEM)
● Scanning electron microscope (SEM)
● Reflection electron microscope (REM)
● Scanning transmission electron microscope (STEM)
● Low-voltage electron microscope (LVEM)

5. Transmission electron microscope (TEM)
● Beam of electrons is transmitted through the specimen
which can be less than 100 nm ultrathin section or a
specimen grid. An image is formed due to interaction of
electrons with the specimen.
● The image is magnified on a imaging device like
fluorescent screen or a photographic film.
● Maximum resolution of ×5,00,000.

6. ● To study Biological tissue specimens, Biological Sections,
organic polymers, Etc.
● The bacterium Escherichia coli (E. coli for short) is crucial
in modern biotechnology. Scientists use it to store DNA
sequences from other organisms, to produce proteins and to
test protein function.
Transmission electron microscope (TEM)

7. Transmission electron microscope (TEM)
Escherichia coli

8. Scanning electron microscope (SEM)
● Works on the principle of raster scanning and helps in
studying the specimens.
● The image is formed due to the conversion of energy in
the electrons into heat, low-energy secondary electron,
High energy backscattered electrons and light emission or
X-Ray emission.
● Specimen surface, such as its topography and
composition can be obtained. The yeast Candida
albicans may cause infections of the mucosa in mouth.
● Maximum resolution of X30,000.

9. Scanning Electron Microscope (SEM)
Candida albicans

10. Reflection Electron Microscope (REM)
● REM is a combination of imaging, diffraction, and
spectroscopy techniques for characterization of topography,
crystal structure, and composition of surfaces of single crystals
● Scattered electrons are being used for the image formation.
● Aspergillus niger is a haploid filamentous fungus which is
used for waste management and biotransformations in
addition to its industrial uses, such as production of citric acid
and extracellular enzymes.

11. Reflection electron microscope (REM)
Aspergillus niger

12. Scanning Transmission Electron Microscope (STEM)
● It is known as the advanced version of SEM
● It focuses on a narrow spot and image of the specimen will
be created by raster scanning technique.
● It also picks up the electron that passes through the
specimen, technique of TEM and helps in creating the image
of a better resolution.
● Maximum resolution of X10,000,000

13. Scanning Transmission Electron Microscope (STEM)
Dicot Stem

14. Low-voltage electron microscope (LVEM)
● This electronic microscope works with low amount of energy
that is as low as 6–25 kV.
● This electronic microscope works on a similar technique as
that of TEM.
● It overcomes the higher resolution, possibility of X-ray
microanalysis of TEM.
● Magnification 1.0–3 nanometers

15. Low-voltage electron microscope (LVEM)
Rat Heart (specific part)

16. Applications of Electron Microscopy to
study Microorganisms
● Helps us to view the organisms that are not visible to naked
eyes nor to that of high microscope.
● Gives us the idea of the morphology of an organism and also
its surface texture.
● Helps us to study the individual cell structure and its
structure.
● Helps us to understand and differentiate with the types of
cells present in various organs.

17. Thank You