BIOLOGY
Investigatory Project Report
Name:
Avantika Gupta
Class:
12 A
School Roll No:
Board Roll No:
School:
G.D. Goenka Public School, Dakshineshwar
Subject:
Biology
Session:
2022-23
Topic: To study drug resistance in bacteria using antibiotics.
ACKNOWLEDGMENT
I would like to express my special thanks to my
Biology teacher "Mr. Reetom Paul" for their
able guidance and support in completing my
project.
I would like to extend my gratitude to our
principal ma'am "Mrs. Sujata Chatterjee"
and vice principal sir "DR. Aniruddha
Bhattacharya" for providing me with all the
facility that was required.
Date:
Avantika Gupta
Class: 12 A
CERTIFICATE
This is to certify that Avantika Gupta, a student
of class XII A has successfully completed this
Investigatory project report titled "To study
drug resistance in bacteria using
antibiotics". Under the guidance of Mr.
Reetom Paul (Biology Teacher) in the academic
year 2022-23.
This report is a bonafide work done by the
student and has been submitted to G.D Goenka
Public School, Dakshineswar, in partial
fulfillment of the Biology practical examination
conducted by CBSE, New Delhi for the award of All
India Senior School Certificate Examination
(AISSCE) in Science.
Signature of Examiner___________________
Signature of Biology Teacher______________
Aim
To study drug resistance in bacteria using
antibiotics.
Antibiotics are the chemical substances produces by
microorganisms to kill other organisms or retard their
growth.
Continuous use of a particular antibiotic against any
microorganism reduces its effect because of a few
bacterial cells develop resistance to antibiotic, may be
due to mutation and thus such resistant strains keep
on growing even in the presence of antibiotics and do
not respond to treatment.
Genes for resistance to antibiotics, like the antibiotics
themselves, are ancient. However, the increasing
prevalence of antibiotic-resistant bacterial infections
stem from antibiotic in medicine.
Any use of antibiotics can increase selective pressure in
a population of bacteria to allow the resistant bacteria
to thrive and the susceptible bacteria to die off. As
resistance towards antibiotics becomes more common,
a greater need for alternative treatments arises
Antibiotic resistance is a form of drug resistance
whereby some (or, less commonly, all) sub-populations
of a microorganism, usually a bacterial species, are
able to survive after exposure to one or more
antibiotics.
Antibiotic resistance is a serious and growing
phenomenon in contemporary medicine and has
emerged as one of the pre-eminent public health
concerns of the 21st century, in particular as it pertains
to pathogenic organisms (the term is especially
relevant to organisms that cause disease in humans).
Antibiotic resistance is becoming more and more
common. Antibiotics and antimicrobial agents are
drugs or chemicals that are used to kill or hinder the
growth of bacteria, viruses, and other microbes. Due to
the prevalent use of antibiotics, resistant strains of
bacteria are becoming much more difficult to treat.
Understanding how bacteria gain this resistance is key
to the development of improved methods for treating
antibiotic resistance.
Materials Required
1. Sterilized Petri dishes
2. Sterilized culture tubes with media
3. Transfer loops
4. Forceps
5. Flask
6. Beaker
7. Burner
8. Penicillin
9. Aureomycin
10. Hay
11. Alcohol
12. Agar
13. Starch
14. Distilled water
Procedure
1. Take 200ml of distilled water in a flask. Add 8 grams of
agar powder and 2 grams of starch. Put a few pieces of dry
hay into the medium and cover the flask with an inverted
beaker.
2. Boil the medium for 5 minutes and then cool it to room
temperature. Place the flask at a warm place. Within 2-3
days, the formation of scum of the cloudy suspension will
appear on the medium indicating the growth of Bacillus
subtilis.
3. Take culture tubes with agar medium and heat the test
tubes in warm water to melt agar. Cooling each test tube to
hold it in hand and the agar remains liquid.
4. Remove the cotton plug and pass the mouth of the test
tube through the burner flame twice. Flaming the transfer
loop after dipping it in alcohol and let it cool.
5. Pick up a loop full of bacterial culture from flask and then
transfer it to the warm agar in the culture tube. Flame the
loop and the mouth of the culture tube and replace the
cotton plug. Roll the culture tube of warm agar between
palms to mix the bacteria well with the agar.
NOTE: Transferring the bacteria should be done as
quickly as possible.
6. Take sterilized Petri dishes.
7. Remove the cotton plug and flame the mouth of the
culture tube.
8. Lift the cover of the petridish at an angle of 45° and quickly
pour it into the medium of the culture tube into the bottom
half of the dish.
9. Remove the culture tube and replace the cover tube with
the bottom half of the dish.
10. Remove the culture tube and replace the cover of the
petridish.
11. Move the covered Petridish along the table top to
distribute the medium evenly.
12. Agar is cooled.
13. Two petridishes are prepared and marked as A & B.
14. Penicillin and Aureomycin solution is prepared by
dissolving the powdered drugs in distilled water.
15. A few discs of filter paper of 1 cm diameter is cut down.
16. A disc is soaked in each of the penicillin and Aureomycin
solutions.
17. Forceps are dipped in alcohol and its tip is put on the
burner flame.
18. Using the sterilized forceps, Penicillin and Aureomycin
soaked discs at two distant sites of Petridish A.
19. Considering Petridish B as control.
20. Both the Petridishes were kept undistributed in warm
place to allow the bacteria to grow.
21. They are observed for several days.
Observation
•The area around the antibiotic discs in the Petridishes will
be clear.
•In other areas, colonies of bacteria will be observed.
• Then The clear area is examined in each Petridishes for few
more days. A few colonies may appear in the clear areas.
These are the colonies of resistant strains of the bacteria.
CONCLUSION
•Antibiotic drugs killed most of the bacterial strain, hence
the areas appeared clear.
• However, a few strains which were resistant in the
bacterial population survived and produced colonies later.
This proves that resistant strains to antibiotics were present
in the bacterial population.
Reference
1) Google
2) NCERT Biology book (class 12)