EFFECTS OF ANTIBIOTICS ON MICROORGANISMS

BIOLOGY PROJECT

KANAK MIRPOURI 12TH - A (STATE BOARD) 29

 Shri. Bhairavnath Shikshan Sanstha`s

Aditya English Medium School& Junior College

Pan Card Club Road, Sneh Park, Baner, Pune 4016/C.R.53/S.M-3

SUBJECT: ___BIOLOGY________________________

INDEX
Sr.No. Contents Pg.No. Remarks
1 Cover page
2 Project title
3 Certificate
4 Acknowledgement
5 Objective
6 Introduction
7 Theory
 History and Discovery
 goal
8 What are Antibiotics?
9 What are Antibiotics made of?
10 How do Antibiotics work?
11 Why are Antibiotics important?
12 Resistance
 what is Antibiotics resistance
 how is resistance spread
13 7 Types of Antibiotics
14 5 basic mechanism of Antibiotics action
against bacterial cell
15 Pros and side effects of taking Antibiotics
16 Experiment work 1 Experiment work 2
 aim  aim
 materials  materials
required required
 procedure  procedure
 observation  observation
 precautions  precautions
result result
17 Precautions
18 Conclusion
19 Bibliography
The objective of this study is to investigate the impacts of antibiotics
on microorganisms. Antibiotics play a pivotal role in healthcare, but
their overuse has led to concerns about antibiotic resistance and
ecological disruption. This research aims to comprehensively assess
how antibiotics affect diverse microbial communities, exploring
changes in composition, diversity, and functional traits. By
understanding these effects, we can develop strategies to mitigate
antibiotic-induced disturbances in microbiomes, promote responsible
antibiotic use, and potentially discover novel ways to combat
antibiotic-resistant pathogens. This study holds significance for public
health, environmental conservation, and the sustainable
management of antibiotic resources.
 INTRODUCTION

Antibiotics Have been widely used for several decades for human
therapy and farming production. Since high percentage of antibiotics
are discharged from the human or animal body without degradation,
this means that different habits from the human body to river water
or soil are polluted with antibiotics.

Antibiotics are chemicals that kill or inhabit the growth of bacteria

and are used to treat bacterial infections. They are produced in
nature by soil bacteria and fungi this gives the microbes and
advantage when competing for food and water and other limited
resources in a particular habit as the antibiotic kills of their
competition only substance that targets bacteria are called
antibiotics.

In this situation it is expected that variable contractions of these

types of microbial inhibitor present in different ecosystems may
affect the structure and productivity of the microbiota colonizing such
habits. This effects can occur at different level including changes in
the overall structure of population, selection of resistance organisms
and alterati2on in bacterial Physiology. In this review I discuss the
available information on how the presence of antibiotics may alter
the microbiota and the consequences of such alterations for human
health and the cavity activity of microbiota from different habitats.

 Antiseptic are used to stabilize surface of living tissues when the

risk of infection is high such as during surgery

 Disinfections are non-selective antimicrobial killing a wide

range of microorganisms including bacteria they are used on
non-living surfaces for example in hospital
 THEORY
History and Discovery
In 1928 at Saint Mary hospital London Alexander Fleming who discovered
Penicillin. Fleming was a bit disorderly in his work and accidentally
discovered penicillin upon returning from Holiday in Suffolk in 1928, he
noticed that a fungus Penicillin notatum had contaminated a cultural
plate of Staphylococcus Bacteria he had accidentally left uncovered

The discovery of penicillin changed the world of medicine enormously

with its development infections that were previously severe and often
fatal like bacteria endocarditis, bacterial meningitis and pneumococcal
pneumonia, could be easily treated

Antibiotics were widely used for treating soldiers during world war-II,
caring for battle wounds infections and pneumonic. By the mid to late
1940s it became widely accessible for the general public

Antibiotics are among the most successful drugs used in the human
therapy. In addition, they have been used for several decades in animal
growth promotion, prophylaxis metaphylaxis, treatment and general
farming production. This wide antibiotics use had led to a different
habitats becoming polluted by large range of concentration of antibiotics.
Since antibiotics are inhibitor of bacterial growth, this situation has an
impact on the structural and the activity of bacterial population. The
effects of the antibiotics on the bacterial population. Has mainly focused
on the aspects related to the human health, in particular the section of
antibiotic-resistance mutants and the acquisition, selections, and spread
of antibiotics resistance genes. While this has obvious revealed to the
treatment of inflectional disease, other aspects of the roles that
antibiotics may play in bacterial population are much less studied in the
comparison.

One aspect to be taken into consideration is that when antibiotics

treatment is needed the effects of the antimicrobial on the microphone
when should be considered unavoidable side effect.
 THEORY
Goal

1. To study the effect of antibiotics on micro-organisms(bacteria).

2. To understand its mechanism.
 WHAT ARE ANTIBIOTICS?

Antibiotics are medication used to fight infections caused by

bacteria. They`re also called antibacterial. They treat infections by
killing or decreasing the growth of bacteria.

The first modern-day antibiotic was used in 1936. Before antibiotics.

30% of all deaths in the United States were caused by bacterial
infection. Thanks to antibiotics, previously fatal infection is curable.

Today, antibiotics are still powerful, lifesaving medications for people

with certain serious infections. They can also prevent less serious
infections from becoming serious.

There are many classes of antibiotics. Certain types of antibiotics

work best for specific types of bacterial infections.

Antibiotics come
in many forms,
including:
 Tablets
 Capsules
 Liquid
 Creams
 Ointments
 WHAT ARE ANTIBIOTICS MADE OF?

The first beta-lactam antibiotic, penicillin, was discovered by

accident. It was growing form a blob of mould on petri dish.
Scientists found that a certain type of fungus naturally produced
penicillin. Eventually, penicillin was produced in large amount in a
laboratory through fermentation using the fungus.

Some other early antibiotics were produced by bacteria found in the

ground soil.

Today, all antibiotic

medication is
produced in a lab.
Some are made
through a series of
chemical reactions
that produce the
substance used in
the medication.

Other antibiotics are at least partly made through a natural but

controlled process. This process is often enhanced with certain
chemical reactions that can alter the original substance to create a
different medication.
 HOW DO ANTIBIOTICS WORK?

Antibiotics are used to treat bacterial infections. Antibiotics take

advantage of the difference between the structure of bacterial cell and
the host cell.

They either prevent the bacterial cells from multiplying so that the
bacterial population remains the same, allowing the hosts defense
mechanism to fight the infection or kill the bacteria for example stopping
the mechanism responsible for building their cell walls.

An antibiotic can also be classified according to the range of pathogens

against which it is effective Penicillin G will destroy only a few species of
bacteria and is known as narrow spectrum bacteria Tetracycline is
effective against a wide range of organisms and is known as broad
spectrum bacteria.

Antibiotics work by blocking vital processes in bacteria, killing the

bacteria or stopping them from multiplying. This helps the body's natural
immune system to fight bacterial infection. Different antibiotics work
against different types of bacteria.
 Antibiotics that affect a wide range of bacteria are called broad-
spectrum antibiotics (eg, amoxicillin and gentamicin).
 Antibiotics that affect only a few types of bacteria are called narrow-
spectrum antibiotics (eg, penicillin).

Different types of antibiotics work in different ways. For example,

penicillin destroys bacterial cell walls, while other antibiotics can affect
the way the bacterial cell works.

Doctors choose an antibiotic according to the bacteria that usually cause

a particular infection. Sometimes your doctor will do a test to identify the
exact type of bacteria causing your infection and its sensitivity to
particular antibiotics.
WHY ARE ANTIBIOTICS IMPORTANT?

The introduction of antibiotics into medicine revolutionized the way

infectious diseases were treated Between 1945 and 1972 average
human life expectancy
jumped by eight years with
antibiotics used to treat
infections that were
previously likely to kill
patients. Today antibiotics
are one of the most
common classes of drugs
used in medicine and make
possible many of the complex surgeries that have become routine
around the world.

If we ran out of effective

antibiotics modern
medicine would be set
back by decades.
Relatively minor surgeries
such as appendectomies
could become life
threatening as they were
before antibiotics became
widely available.
Antibiotics are sometimes used in a limited numbers of patients
before surgery to ensure that patients do not contact any infections
from bacteria entering open cuts Without this precaution the risk of
blood poisoning would become much higher and many of the more
complex surgeries doctors now perform may not be possible.
 Resistance
WHAT IS ANTIBIOTICS RESISTANCE?
Antibiotic resistance happens when bacteria change to protect
themselves from an antibiotic. Bacteria become resistant when their
genes mutate after being in contact with an antibiotic. These changes
allow the bacteria to survive or 'resist' the antibiotic so that the antibiotic
no longer works to kill the bacteria or stop them from
multiplying.

Unfortunately, bacteria can also develop antibiotic resistance through

contact with other bacteria. Resistant bacteria can pass their genes to
other bacteria, forming a new antibiotic-resistant 'strain of the bacteria.

The more antibiotics are used, the more chances bacteria have to
become resistant to them.

As more antibiotics stop working against bacterial infections, doctors will

have fewer antibiotics to use. Many common infections may eventually
become untreatable with medicines. The World Health Organization
(WHO) has warned that antibiotic resistance is one of the greatest threats
to global public health today.

Bacteria are termed drug resistant when they are no longer inhibited by
an antibiotic to which they were previously sensitive The emergence and
spread of antibacterial resistant bacteria has continued to grow due to
both the over use and misuse of antibiotics

Treating a patient with antibiotics causes the microbes to adapt or die

this is known as selective pressure if a strain of a bacteria species acquires
resistance to an antibiotic it will survive the treatment As the bacterial
cell with acquired resistance multiplies this resistance is passed on to its
offspring In ideal conditions some bacterial cells I can divide every 20
minutes, therefore after only 8 hours in excess of 16 million bacterial cells
carrying resistance to that antibiotic could exist
 Resistance
HOW IS RESISTANCE SPREAD?

Antibiotic resistance can either be inherent or acquired Some

bacteria are naturally resistance to some antibiotics due to their
physiological characteristics. This is inherent resistance Acquired
resistance occurs when a bacterium that was originally sensitive to
an antibiotic develops resistance.

For example resistance genes can be transferred from one plasmid to

another plasmid or chromosome or resistance can occur due to a
random spontaneous chromosomal mutation.
 7 TYPES OF ANTIBIOTICS

Although there are well over 100 antibiotics the majority come from
only a few types of drugs. These are the main classes of antibiotics

ANTIBIOTIC EXAMPLE
PENICILLIN AMOXICILLIN
CEPHALOSPORINS CEPHALEXIN
FLUOROQUINOLONES ERYTHROMYCIN
MACROLIDES OFLOXACIN
SULPHONAMIDES BACTRIM
AMINOGLYCOSIDES TETRACYCLINE
TETRACYCLINES GENTAMICIN
5 BASIC MECHANISM OF
ANTIBIOTICS ACTION AGAINST
BACTERIAL CELL

 Inhibition of cell wall synthesis (most common mechanism)

 Inhibition of protein synthesis (translation)
 Alteration of cell membranes
 Inhibition of Nucleic acid synthesis
 Antimetabolite activity

The ribosome is a major target for Antibiotics Drugs inhibit ribosome

function either by interfering in messenger RNA translation or by
blocking the formation of peptide bonds at the peptidyl transferase
centre These effects are the consequence of the binding of drugs to
ribosomal subunits
PROS AND SIDE EFFECTS OF TAKING
ANTIBIOTICS
PROS
• Antibiotics can slow down the growth of bacteria and kill many
types of infections
•In some cases such as before surgery antibioticscan prevent
infection from occurring
• Antibiotics are fast acting some will begin working within a few
hours
• They are easy to take most Antibiotics are oral medications Your
doctor may decide to give you an injection, if it is imperative that the
medicine gets into your system quickly

SIDE EFFECTS
The most common side effects of antibiotics is it affects the digestive
system Antibiotics commonly cause the following side effects:
 Diarrhea
 Nausea
 Vomiting
 Rash
 Upset stomach
 Sensitivity to sunlight, when taking tetracycline
 With certain antibiotics or prolonged use fungal infections of
the mouth digestive tract and vagina
 EXPERIMENT WORK 1
AIM: This project aims to study the effect of antibiotics on
microorganisms.

MATERIALS REQUIRED: Potato, agar, dextrose, distilled water, four

different types of antibiotics (such as penicillin, streptomycin,
aureomycin, and Terramycin), syringe, oven sterilized Petri dish, flasks,
beakers, pipettes, garden soil, glass marker pen, etc

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.

2.Meat Extract Agar Medium

 Weigh 3g beef extract, 10g peptones, 5g NaCl and mix these in 1 litre
of distilled water
 Heat the mixture to 65° Celsius stirring until the material is completely
dissolved
 Filter the mixture through filter paper and adjust the pH to 7.2 to 7.6
by adding a bit of sodium bicarbonate
 Add 20g Agar to the broth and autoclave the medium at 15 pounds
pressure for 15 mins
B. Effects of antibiotics on soil micro-organisms
 Take 2 g of soil and dissolve it in 10 ml of water in a beaker. Let the soil
particle settle down.
 Take 5 oven sterilized Petri dishes and pour 1 ml of soil suspension into
each of the plates. Now pour Iml of the four antibiotics separately into
four Petri dishes with the help of a syringe, and mark them with a
marker pen. Leave the fifth Petri dish without antibiotics to serve as a
control.
 Pour PDA into each of the Petri dishes and mix the suspension by
rotating the Petri dishes. Leave the Petri dishes undisturbed in a warm
place

OBSERVATION:
The effect of different antibiotics on the microorganisms can be
assessed by counting the number and size of the colonies growing
in the Petri dishes.
Sr.No. Antibiotics No. of colonies in a Petri dish
1. Penicillin NIL
2. Streptomycin 2-3
3. Terramycin NIL
4. Chloromycetin 1-2
5. Control 30-40

PRECAUTIONS:
• Do not expose the culture of the Petri dish to the atmosphere
Sterilise the Petri dishes properly in the oven before use Use proper
kind of stains for different types of microorganisms
RESULT:
Penicillin and Terramycin were the most effective antibiotic against
microorganisms in the soil with Streptomycin and Chloromycetin
not too far behind.
The surviving colonies of microorganisms in the petridish may have
developed a resistance to the stated antibiotics and there is ahigh
possibility that the antibiotic would be less and less effective on
future generations of the surviving colonies
 EXPERIMENT WORK 2
AIM: To see the effect of antibiotics on bacteria count

MATERIALS REQUIRED: 10 test-tubes of sterilized water, 10 PCA(Agar)

plates, Bunsen burner, Graduated cylinder, Ethanol (Used for sterilizing
just flame is enough most cases), Glass hockey stick, Pipettes,
Refrigerator, Incubator (A warm cabinet for growing bacteria), Scale,
Large beaker, Hot plate, Sample antibiotic.

PROCEDURE:
Step 1 Prepare a culture media plate for growing bacteria

step 2 Get a sample of polluted water for test Mix 2 ml of polluted water
with 10 ml chicken broth in a test tube and incubate it for 24 hours so the
bacteria will reproduce and increase Usually this is done on a device that
constantly moves so the bacteria can freely move in the liquid Most likely
you will not have a vibrator, so it is good if you shake the test tube a few
times during this incubation period

Step 3 While the bacteria are being incubated prepare some antibiotic
disks as described here (Antibiotic disks can also be purchased from
biology suppliers) Break an antibiotic capsule (here using Ampicillin) and
empty the contents in a clean petri dish One capsule will be enough for
hundreds of disks Dispose of the plastic shell and add a few drops of water
to the remaining powder Cut some filter papers in small pieces and soak
them in the antibiotic solution Let the disks dry in a clean space You may
cover them with another filter paper to protect them from dust. Although
they are known as antibiotic disks you can cut them in small squares The
reason that we use filter paper is that other papers often have starch and
other polymers that may affect the results of our experiments Filter
paper is pure cellulose fiber
Step 4 Use the bacteria that you have grown in step 2 and prepare
dilution of bacteria

1. Prepare 1 10 dilution of the sample To do this take 2ml of the

sample and blend it with 18ml of distilled water
2. Pipette 0 1ml of each dilution onto a Plates Count Agar (PCA) plate
3. Take a glass hockey stick submersed in ethanol and run it through a
flame to sterilize it (Glass hockey stick is a glass rod bent on one
end like a hockey stick It is used to spread bacteria on the surface
of agar plate You may use a steel spoon instead)
4. Let it cool and use it to spread dilution around the plate
5. Do this on two plates for each of the five different dilutions
6. Place an antibiotic disk on the plate of dilution
7. Incubate the plate at 35 degrees Celsius for 24 hours and then
count the bacterial colonies
8. Take 3 nutrient agar plate and added 0 5ml of the solution on each
of plates
9. Leaving one plate without any antibiotics placing one antibiotic disk
on the second plate and two antibiotic disks on the third plate All
plates were incubated for 48 hours
Observations:
 PRECAUTIONS

Several important steps can be taken to ensure proper and effective

antibiotic use:
 Take antibiotics only for bacterial infections. Don't use
antibiotics for conditions caused by viruses such as the
common cold, flu, cough, or sore throat.
 Take antibiotics as directed by a healthcare professional.
Using the wrong dose, skipping doses, or taking it longer or
shorter than directed might contribute to bacterial resistance.
Even if you feel better after a few days, talk with your
healthcare professional before discontinuing an antibiotic.
 Take the right antibiotic. Using the wrong antibiotic for an
infection might lead to resistance. Don't take antibiotics
prescribed for someone else. Also, don't take antibiotics left
over from a previous treatment. Your healthcare professional
will be able to select the most appropriate antibiotic for your
specific type of infection.
 CONCLUSION

Antibiotics are a very effective tool to fight against bacterial

infections and have overall improved the life of humans as a race but
it does not come without any side effects. Improper and irregular use
of antibiotics cause microorganisms to develop resistance against
them and hence require newer generations of antibiotics to be
developed to help fight against them, Antibiotic resistance is
considered a great risk to our future. Antibiotics in some cases also
cause side effects such as diarrhea, nausea and vomiting in humans
and may even disrupt natural ecosystems when introduced to them
(the effect of these antibiotics on microorganisms in the soil is shown
in the experiment above). The only way to combat these side effects
is to spread awareness about the precautions of using antibiotics and
consulting a licensed doctor before turning to antibiotics as a magic
solution to your ailment.
The growth of bacteria around the antibiotic disks is less Inhibition
zones are more in the plates with more antibiotic disks
Hence, antibiotics stop the proliferation of bacteria
 BIBLIOGRAPHY

1)Website
a) www.nps.org.au
b) www.healthline.com
c) genomemedicine.biomedcentral.com
d) www.ncbi.nlm.nih.gov
e) www.wikipedia.org f) www.reddit.com

2) Books
a) Comprehensive Practical Manual
b) HC biology Class XI