effects of antibiotics on microorganisms

1. CERTIFICATE
This is to certify that the project work entitled “STUDY
OF EFFECTS OF ANTIBIOTICS ON MICROORGANISMS” is
the bonafide record of work done by SANJAY.N.V.
Roll NO. 8 in partial fulfillment of the requirement for
the award of the grade XII-A1 during the academic year
2019 – 2020.
Viva voce held on:
INTERNAL EXAMINER EXTERNAL EXAMINER

2. ACKNOWLEDGEMENT
I wish to express my deep gratitude and sincere thanks
to principal. Mrs. P.LALITHA for her encouragement and
for all the facilities that she provided for this project
work. I extend my heartily thanks to Mr.C.NAVEEN
KUMAR (Biology teacher), who guided me to the
successful completion of this project. I take this
opportunity to express my deep sense of gratitude for
his invaluable guidance, constant encouragement,
which has sustained my efforts at all stages of this
project work. I can’t forget to offer my sincere thanks to
my classmates who helped me to carry out this project
work successfully and for their valuable advice and
support, which I received from them time to time.
Finally I take great honor in thanking my family
members for their moral support and encouragement.
SANJAY.N.V.
XII-A1

3. CONTENT
NAME: SANJAY.N.V. CLASS: XII- A1
S.NO PARTICULAR P.NO
1. ABSTRACT
2. INTRODUCTION
3. AIM
4. MATERIALS REQUIRED
5. PROCEDURE
6. OBSERVATION
7. RESULT AND CONCLUSION
8. BIBLIOGRAPHY
DATE OF SUBMISSION TEACHER’S SIGNATURE

4. ABSTRACT
Antibiotics are the organic secretion produced by micro
– organisms, which in low concentrations are
antagonistic to the growth of other micro – organisms
(mostly pathogens). Antibiotics have proved very useful
in combating several bacterial diseases in man and
animal. Antibiotics are commonly obtained from
actinomycetes and some eubacteria. Some of the
important antibiotics are streptomycin, Aureomycin,
teramycin, Chloromycetin, erythromycin, neomycin etc.
Soil is a natural medium that harbors several types of
micro – organism. These micro- organisms can be frown
on culture media. The effect of different types of
antibiotics can be studied on the growth of micro -
organism growing in culture medium. This is an
important subject, therefore the study of effect of
antibiotics on micro - organism has been taken for the
present project.

5. INTRODUCTION
Antibiotics are either naturally occurring or man-made
chemicals that can be divided into different classes such
as ß-lactams, quinolones, tetracyclines, macrolides. The
main source of antibiotics in the environment is
anthropogenic input from wastewater discharge,
manure disposal, and aquaculture. Once antibiotics
enter the ecosystems, they can be treated as an
ecological factor, driving the evolution of the
community structure. Accordingly, the change of
community structure influences the ecological function
of soil and water ecosystems such as biomass
production and nutrient transformation. Indirect effects
from the antibiotic disturbance to the micro-ecosystem
are largely unknown, and it is expected that such
disturbance might have significant and long-term
effects on the rate and stability of ecosystem
functioning. Therefore, this review summarizes current
knowledge of the effects of antibiotics on microbial

6. community in natural habitat. In order to provide an
update on current knowledge of antibiotic effects, this
review emphasizes on how antibiotics alter the
microbial community structure, inhibit or promote
ecological functions, and affect the magnification of
resistance, mainly in the context of the natural
environment.

7. AIM
 The aim of this project is to study the effect of
antibiotics on micro – organisms.

8. MATERIALS REQUIRED
1.Potato.
2.Agar.
3.Dextrose.
4. distilled water.
5.four different types of antibiotics (such as
penicillin, streptomycin, aureomycin,
teramycin).
6.Syringe.
7. oven sterilized petridish.
8.Flasks.
9.Beakers.
10.Pipettes.
11. Garden soil.
12. Glass marker.

9. PROCEDURE
A. Preparation of culture Medium
1. Potato Dextrose Agar (PDA) Medium. Take 200 g of
peeled potato chips.
Boil them with 500 ml of water in a beaker for 15
minutes. Squeeze the potato pulp thus obtained
through a muslin cloth and keep it in a flask. Take 20 g
of agar in a beaker and warm it with 500 ml of water.
Mix both the solution of potato and agar and add 20 g
dextrose to it. Thus one litre of PDA medium is
prepared. Autoclave the medium at 15 pounds pressure
for 15 minutes.
B. Effects of antibiotics on soil micro0 organisms
i) Take 2 g of soil and dissolve it in 10 ml of water in a
beaker. Let the soil particle settle down.
ii) Take 5 oven sterilized Petri dishes and pour 1 ml of
soil suspension in each of the plates. Now pour 1ml of
the four antibiotics separately in four Petri dishes with

10. the help of syringe, and mark them with marker pen.
Leave the fifth Petridis without antibiotic to serve as
control.
iii) Pour PDA in each of the Petri dishes and mix the
suspension by rotating the Petri dishes. Leave the Petri
dishes undisturbed at a warm place.

11. OBSERVATION
Colonies of micro- organisms appear on the culture
medium, count the colonies in each Petri dishes and
present your observation in the following table:
The effect of different antibiotics on the micro –
organisms can be assessed by counting the number and
size of the colonies growing in the petridishes.
S.No. Antibiotics No. of
colonies in a
petridish
1. Pencillin NIL
2. Streptomycin 2-3
3. Terramycin NIL
4. Chloromycetin 1-2
5. Control 30-40

12. CONCLUSION
Pencillin and Terramycin was most effective antibiotic
against microorganism in soil.

13. BIBILOGRAPHY
 https://www.scribd.com/doc/296046426/Biology-Investigatory-project
 https://www.scienceproject.com/projects/intro/Senior/SB142.asp
 https://www.researchgate.net
 https://www.google.com/
 https://brainly.in/
 http://www.all-science-fair-projects.com/project994_134.html
 https://in.yahoo.com/
 https://www.bing.com/