microorganisms, classification of microorganisms, bacteria, shapes of bacteria, protozoa, algae, fungi, viruses. bacterial growth curve, factors affecting growth of bacteria, culture media, composition of culture media, types of culture media, methods of culture media, isolation of microbes, streak culture, stroke culture, lawn culture, pour plate culture, stab culture, simple media, enriched media, enrichment broth, differential media, transport media, selective media, anaerobic media

1. PRESENTEDBY: JYOTI BHAGAT

3. Protozoa
Algae
Fungi
Virus
Bacteria

4. Bacteria are small single celled organisms that are
neither plants nor animals.
Types
1.Spherical
2.Rod-shaped
3.Spiral
4.Spirochaetes
5.Actinomycetes
6. Mycoplasmas

7.  Spherical: Single bacterium is called a coccus, group of
coccus is called cocci. Examples-streptococcus group.
 Rod-shaped: Also known as bacilli (singular bacillus). Some
rod-shaped bacteria are curved. These are also known as
vibrio. Examples- Bacillus anthracis.
 Spiral: known as spirilla (singular spirillus). If their coil is
very tight they are known as spirochetes.
 Leptospirosis, Lyme disease, and syphilis are caused by
bacteria of this shape.

10.  Lag Phase-The bacteria adjust themselves to their new
surroundings.
 Log Phase- This is the growth phase of the culture. In this
phase bacteria divide rapidly to multiply at an exponential
rate.
 Stationary phase- Stationary phase is the stage when
growth ceases but cells remain metabolically active.
 Death/ Decline Phase- Due to unfavorable conditions, there
is a steady decline in the number of cells, and the amount of
death surpasses the amount of bacterial growth.

11.  Carbon dioxide
 Temperature
 pH
 light and other Radiations
 Osmotic Effect
 Mechanical and Sonic Stresses

12.  Definition
The food material or substances required for growing
microorganisms in vitro(outside the body) is called culture
media.
Culture media means an environment where bacteria can grow
and multiply. It provides proper nutrition and pH for the growth
of bacteria.

13. 1. Water: distilled water is used for the preparation of the
media.
2. Electrolytes: sodium chloride is used as electrolyte.
3. Peptone: it is obtained from animal source and plant
source.
4. Agar: it is used for solidifying of the culture media.
 Agar is also known as agar-agar because it is prepared by using
cell wall of algae as Gelidium.

14.  1. Based on physical state
Solid, semisolid and liquid
2. Based on the presence or absence of oxygen
◦ Anaerobic media
◦ Aerobic media
3.Based on nutritional factors
-Simple media - Enrichment broth
-Differential media - Selective media
- Enriched media - Anaerobic media
- Transport media

15. 1.Simple media
 Nutrient broth- it is used for studying the bacterial growth
curve.
 Nutrient agar- it is used for performing biochemical test.
Catalase, oxidase.
 Semi-solid media- it is used for the detection of motility of
bacteria.

16.  2. Enriched media
◦ Blood agar: it is prepared by using sheep blood. It is used for the
detection of hemolysis property of bacteria (Alpha & Beta
hemolysis).
◦ Chocolate agar: when agar is more heated it becomes brown
colour and is called chocolate agar. It is mainly used for special type
of bacteria- Haemophilia influenzae.
◦ Loeffler Serum: it is prepared from horse serum and it is mainly
used for the Corneybacterium diphtheriae.
◦ BHI agar (brain heart infusion): it is present in Blood culture
bottle and is used for the bacterial culture.

17.  3. Enrichment broth
◦ It is a type of liquid media in which some inhibitors agent is added
to allow only selective organisms to grow and inhibit other
organisms.
◦ It is used for stool culture, sputum culture.
◦ Tetrathionate broth- used for the isolation of Salmonella typhi.
◦ Gram negative broth- used for isolation of Shigella.
◦ Alkaline Peptone water: mainly used for isolation of Vibrio
Cholera.

18.  4. Selective media
◦ Selective media is a type of solid media in which some inhibitors
agent is added to allow growth of special type of bacteria and
inhibit other organisms.
◦ L.J media (Lowenstein Jensens Media): it is used for the isolation
of Mycobacterium Tuberculosis.
◦ DCA (Deoxycholate citrate agar): it is used for the isolation of
Salmonella and Shigella.
◦ PTA (Potassium tellurite Agar): it is used for the isolation of
Corneybacterium diphtheriae.

19.  5. Differential media
◦ It is mainly used to differentiate between different bacterial groups.
◦ It does not kill organisms. It only indicates if a target organism is
present.
◦ It leads to a visible change when growth of target organisms are
present.
◦ The presence of certain dyes or chemicals helps to differentiate the
organisms that will produce characteristic changes or growth
patterns and are used for identification or differentiation.

20. Macconkey Agar- it is a special type of differential media which is
mainly used for the isolation of gram negative bacteria.
 lactose fermenting bacteria- produce a pink colour colony on
Macconkey Agar. Example- Escherichia coli.
Non lactose fermenting bacteria- produce a colourless colony on
macconkey agar. Example – Shigella.
CLED agar (Cysteine lactose Electrolyte- deficient)
It is used for isolating and enumerating bacteria from urine.

21.  6. Transport media
◦ This media is used to transport clinical specimens from one
laboratory to another.
◦ It has special quality that it does not allow to multiply
microorganisms but help the microorganisms to remain in viable
condition.
◦ Pike’s media- for transport of streptococcus bacteria.
◦ Amies media- for transport of Neisseria.
◦ VR (Venkatraman-ramakrishnan media)- for transport of
vibrio cholera.

22.  7. Anaerobic media
◦ Anaerobic culture media contains reducing agents such as
cysteine.
◦ Anaerobic bacteria have to be cultivated in the absence of oxygen.
◦ Examples – Thioglycollate broth and cooked meat broth.

23.  Streak culture
 Lawn culture
 Stroke culture
 Stab culture
 Pour- Plate culture
 Liquid culture

24. Streak culture
 Routinely used method to isolate bacteria.
 One loop full of culture is made as a primary inoculum and then it is
distributed thinly over the plate by streaking it with the loop in series
of parallel lines in different segments of the plate.
 Loop flamed and cooled between different sets of streaks.

25. Lawn culture
 Also called as carpet culture.
 Provides a uniform growth of the bacterium.
 Useful for bacteriophage typing and antibiotic sensitivity testing.
 Prepared by flooding the surface of the plate with a liquid
culture or suspension of the bacterium, pipetting off the excess
inoculum and incubating the plate.
 Alternatively the surface of the plate may be inoculated by
applying a swab soaked in the bacterial culture or suspension.

26. Stroke culture
 Made in tubes containing agar slopes(slant).
 Employed for providing a pure growth of the bacterium for
slide agglutination and other diagnostic tests.

27. Stab culture
 Prepared by puncturing with a long straight, charged wire in a
suitable medium such as nutrient gelatin or glucose agar.
 Medium is allowed to set with the tube in the upright position,
providing a flat surface at the top of the medium.

28. Pour plate culture
 Tubes containing 15ml of agar medium are melted and left to cool in a
water bath at 45 degree celcius to 50 degree celcius.
 Dilutions of the inoculum are added in 1ml volume to the molten agar,
mixed well.
 Contents pulled in sterile petridishes and allowed to set.
 After incubation colonies will be seen well distributed throughout the
depth of the medium.
 Enumerated using colony counters.
 Gives an estimate of the viable bacterial count in a suspension and is
the recommended method for quantitative urine cultures.

29.  Isolation refers to the separation of strain from a natural,
mixed population of living microbes, as present in the
environment.
OR
 It is the process of developing a pure culture by separating one
species of microbe from a mixture of many other species. A
pure culture is a culture that contains only one species of
microbe.

30.  This aids in the characterization of biodiversity in microbial
ecology.
 It helps in determining the organism’s name to the genus and
species level, which can assist in determining whether the
organism is beneficial or harmful and whether it cause disease.
 In research study, identifying a new isolate which carries out
an important process.

31.  Protozoa or protozoans are single-celled eukaryotic
microorganisms.
 Protozoa are oval or spherical shaped.
 Some are elongated.
 Cells can be as small as 1 μm in diameter and as large as 2,000
μm, or 2 mm that are visible without magnification.
 Protozoa lack cell walls.
 Phytoflagellate protozoa are plantlike that obtain their energy via
photosynthesis.
 Some can swim through water by the beating action of short, hair
like appendages (cilia) or flagella.
 Example – Amoeba, Paramecium.

34.  The term algae is derived from the Latin word “alga” which means
“seaweed”.
 Algae are photosynthetic organisms that possess photosynthetic
pigments such as chlorophyll.
 Algae lack true roots, stems, and leaves characteristic of vascular
plants.
 Some algae are unicellular whereas others are multicellular.
 They may also form colonies.
 Most algae are aquatic and others are terrestrial that may be found
on moist soil, trees, and rocks.
 The scientific study of algae is called phycology.
 Some algae reproduce asexually and others reproduce by sexual
reproduction. Red algae and green algae have both in their life cycle.
 Fucus, Porphyra, Spirogyra are examples.

36.  Fungi are eukaryotic, non-vascular, non-motile and heterotrophic
organisms.
 They may be unicellular or filamentous.
 They reproduce by means of spores hence have no embryonic stage.
 Mode of reproduction can be sexual (by the production of
pheromone chemical) or asexual.
 Fungi lack chlorophyll and hence cannot perform photosynthesis.
 Fungi store their food in the form of starch.
 The nuclei of the fungi are very small.
 Some fungi are parasitic and can infect the host.
 Examples include mushrooms, moulds and yeast.

38.  A virus is an infectious agent contains a segment of nucleic acid
(either DNA or RNA) surrounded by a protein coat.
 Viruses are unique because they are only alive and able to multiply
inside the cells of other living things. The cell they multiply in is
called the host cell.
 A virus is made up of a core of genetic material surrounded by a
protective coat called a capsid which is made up of protein.
 The virus particles burst out of the host cell into the extracellular
space resulting in the death of the host cell. Once the virus has
escaped from the host cell it is ready to enter a new cell and multiply.
 Viruses may be rod-shaped, almost spherical, or other shapes.
 Viruses can spread through touch, respiratory droplet, direct contact,
bodily fluids, contaminated food or water, insects and during
childbirth.