1. Growing of microorganism
Microbiology 2011

2. Nutritional Types of Organisms
Autotrophs and Heterotrophs

3. Autotrophs Make their own food using simple carbon sources
1. Photoautotroph: Energy from sunlight and carbon from CO2
2. Chemoautotroph: Inorganic compounds as carbon and energy source

4. Heterotrophs
Not able to synthesize food from inorganic compounds, need carbohydrates, fatty acids or alcohols
1. Photoheterotroph - Sunlight as energy source, preformed organic molecules for carbon source
2. Chemoheterotroph - Use preformed organic molecules for both carbon and energy source

5. Nutritional requirement

6. Nutritional requirements
1. Require a source of energy
Chemotrophs - chemical compound
Phototrophs - radiant energy
Source of electron
Lithotrophs - reduce inorganic compounds as electron donors.
Organotrophs - organic compounds as electron donors.

7. 3. Require carbon for synthesizing cell component.
4. Nitrogen- cell component.
5. Oxygen, Sulphur and phosphorous.
6. Traces elements like metal ions for their normal growth.
7. Vitamins and vitamin like compound- fn. as co-enzyme for several enzymes.
8. Water.
Bacteria requires nutrients in aqueous solution.

8. Preparation of media

9. Bacterial media
Chemically defined media are required for the cultivation of organism.
Certain complex raw materials such as
Peptones
Beef extract
Yeast extract
Agar

10. Nutrient Agar Beef extract - 3g Peptones - 5g Agar - 15g
Water ,000ml

11. Preparation of media
Each ingredient or the complete dehydrated medium, is dissolved in appropriate volume of distilled water.
The pH of the fluid medium is determined.
Agar is added and the medium is boiled to dissolve water- solid medium.
The medium is dispensed into tube or flask.
The medium is sterilized, generally by autoclaving,

12. Media Preparation

13. Culture media Plate Broth Slant

14. Bacteria colonies

15. Physical conditions required for growth.
Temperature:
Optimum growth temperature- temperature that allows for most rapid growth during a short period of time (12 to 24h).
Psychrophiles - able to grow at 00 C or lower, they grow best at higher temperature.
Mesophiles – within a range of 25 to 400C
Thermophiles – grow best at temperature above 450 C.

16. 2. pH(Acidity/Alkalinity)
Optimal pH for growth
best at 7.
Can tolerate pH 5 to pH 8
Acid-tolerant bacteria - acidophiles
Lactobacillus
Streptococcus
Alkaline-tolerant bacteria - alkalophilic
Vibrio cholerae as low as 2.0

17. 3. Gaseous requirement O2 and CO 2
1. aerobic bacteria - require oxygen for growth.
2. Anaerobic bacteria - do not use oxygen to obtain energy. Oxygen is toxic for them and cannot grow when incubated in an air atmosphere.
3. Non-stringent or tolerant anaerobes - can tolerate low level of oxygen.
4. Stringent or strict anaerobes- cannot tolerate even low level of oxygen/air.

18. Facultative anaerobic bacteria:
can utilize oxygen if it is present but can grow in its absence.
6. Microaerophilic bacteria:
require low level of oxygen for growth but cannot tolerate the level of oxygen present in an air atmosphere
Obligate (strict) aerobes:
organism have an absolute requirement for oxygen.
Obligate (strict) anaerobes:
cannot utilize oxygen. Some can be killed by traces of oxygen.

19. Oxygen Aerobic bacteria - Bacillus Anaerobic bacteria – Clostridium
Sulfur
Microaerophilic – Treponema palladium
Facultative anaerobe – Bacillus
prefers oxygen, but can grow without

20. Pure culture
A culture containing only one species of organism.

21. END