Sterilization Types of sterilization Physical sterilization Dry heat Moist heat Radiation Ultrasonic method

1. KUVEMPU UNIVERSITY
SAHYADRI SCIENCE COLLEGE
PRESENTED BY:
TEJASHWINI.M.HAVANUR
1st MSc I Sem
Dept of Biotechnology,
Sahyadri Science College,
Shivamogga.
SEMINAR TOPIC ON
‘PHYSICAL METHODS OF STERLIZATION’’

2. CONTENTS
INTRODUCTION
HISTORY
PHYSICAL METHODS OF STERILIZATION
PHYSICAL AGENTS
STERILIZATION BY HEAT
STERILIZATION BY FILTRATION
STERILIZATION BY RADIATION
IMPORTANCE OF STERILIZATION
CONCLUSION
REFERENCE

3. INTRODUCTION
• Cleaning plays an important preparatory role before sterilization or
disinfection by removing soil and other dirt and reducing the
microbial burden ,making sterilization more effective.
• Sterilization is defined as the process by which the surface or medium
is freed of all living micro-organisms either in the vegetative form or
spore state.

4. HISTORY
JOSEPH LISTER CHARLES CHAMBERLAND

5. PHYSICAL METHODS OF STERILIZATION
Physical method of sterilization is the removal of all forms of micro-organisms
by applying moist heat or dry heat or by various methods of filtration to free
the media of microbes.

6. PHYSICAL AGENTS
Sunlight: Sunlight possesses appreciable bactericidal activity and plays an
important role in the spontaneous sterilization that occurs under natural
conditions.
Drying: Moisture is essential for the growth of bacteria. Four-fifths of the weight
of the bacterial cell is due to water. Drying in air has , therefore a deleterious
effect on many bacteria.
Heat: Heat is the most reliable method of sterilization and should be the method
of choice unless contraindicated , materials that may be damaged by heat can be
sterilized at lower temperatures , for longer periods or by repeated cycles.

7. STERLIzATION BY HEAT
HEAT: It is a preferred agent of sterilization for all materials not damaged by it .
1.DRY HEAT: This is the most widely used method of sterilization.
INSTRUMENT: “HOT AIR OVEN”
It is a common sterilizing device where the hot air circulates in an insulated
double walled cabinet heated by electricity and is constructed to withstand a high
temperature.
A holding period of 1600 Celsius,
for 1 hour is used to sterilize
test tubes , conical flasks ,
petriplates.

8. MODE OF ACTION:
• Dry heat kills microorganisms by oxidizing molecules , the essential
cell constituents are destroyed and the organism dies .
• The temperature is maintained for almost an hour to kill the most
difficult of the resistant spores

9. 2.MOIST HEAT:
• Heat or steam obtained by boiling water
produces moist heat at a very high
temperature.
• Moist heat has a higher penetrating
capacity than dry heat while heat
denatures substances such as proteins
by coagulation, with percentage increase
in temperature for coagulation becomes
less.
• INSTRUMENT: “AUTOCLAVE”

10. MODE OF ACTION:
• Moist heat destroys microorganisms by the irreversible coagulation
and denaturation of enzymes and structural proteins

11. STERILISATION BY RADIATION
Radiation may be defined as energy transmitted through space or a material
medium .the source of radiation are particle radiation ,electromagnetic radiation
and acoustic radiation.
Two type of radiation are used for sterilization: –
1.Ionizing Radiation : these have high energy and ionize the target molecule i.e.,
they disturb the ionic configuration.
Ex: Gamma rays (cobalt 60), X-rays.
2.Non-Ionizing Radiation : these are less penetrative and can be controlled and
made unidirectional.
Ex : UV rays.

12. MODE OF ACTION :

13. ULTRASONIC methods
Sound waves beyond the audible range are called ultrasonic waves ,sound
waves which are also called acoustic radiation have different frequencies where
high frequency sound waves have microbiocidal properties
Its mode of action is when a high frequency sound waves create gas bubbles in a
liquid system and when the bubbles collapse they create a very high pressure
resulting in the rupture of cell wall ,membranes etc of the cells
(microbes)subjected to sonication .

14. MODE OF ACTION:

15. IMPORTANCE OF STERILIZATION
Sterilization is an important process in research development
laboratories.
 This process is used in the preparation process of cultures and other
microbiology experiments .
It prevents the contamination of instruments and areas in the
pharmaceutical industries.
It is used to prevent the growth of unwanted microbes in pure
cultures required for research studies so that one microbe is not
mistaken for the other.

16. CONCLUSION
Sterilization is one of the most important technique used to prevent the
microbial contamination.
People have been practiced since last centuries have developed many methods
of sterilization to remove the microbial population which is harmful.
Sterilization have been used many small and large scale industries such as like in
food industries, dairy industries , medical laboratories and pharma.
It is the basic need of every microbiology laboratories where sterilization is a
daily routine process.

17. REFERENCE
Ananthanarayan and Paniker’s “TEXT BOOK OF MICROBIOLOGY”
8th Edition.
Jacquelyn G. Black “MICROBIOLOGY PRINCIPLES AND EXPLORATIONS”
5th Edition.