Growing of microorganism

Microbiology 2011

Nutritional Types of Organisms

Autotrophs and Heterotrophs

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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

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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

Nutritional requirement

Nutritional requirements

1. Require a source of energy

• Chemotrophs - chemical compound

• Phototrophs - radiant energy

2.Source of electron

Lithotrophs - reduce inorganic compounds as electron donors.

Organotrophs - organic compounds as electron donors.

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.

Preparation of media

Bacterial media

• Chemically defined media are required for the cultivation of organism.

• Certain complex raw materials such as

1.Peptones

2.Beef extract

3.Yeast extract

4.Agar

Nutrient Agar

• Beef extract - 3g

• Peptones - 5g

• Agar - 15g

• Water - 1,000ml

Preparation of media

1. Each ingredient or the complete dehydrated medium, is dissolved in appropriate volume of distilled water.

2. The pH of the fluid medium is determined.

3. Agar is added and the medium is boiled to dissolve water- solid medium.

4. The medium is dispensed into tube or flask.

5. The medium is sterilized, generally by autoclaving,

Media PreparationMedia Preparation

Culture media

http://student.ccbcmd.edu/courses/bio141/lecguide/unit2/control/images/broth.jpg

http://82.43.123.182/globalplantclinic/images/Bacteria_plate.jpghttp://www.mushmush.nl/images/methods/working_with_agar/slant.jpg

http://student.ccbcmd.edu/courses/bio141/labmanua/lab7/images/negmotility.JPG

Plate

Slant

Broth

Bacteria colonies

http://textbookofbacteriology.net/growth.html

Physical conditions required for growth.

1. 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.

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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

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.

5. 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.

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Oxygen

• Aerobic bacteria - Bacillus

• Anaerobic bacteria – Clostridium

– Sulfur

• Microaerophilic – Treponema palladium

• Facultative anaerobe – Bacillus

– prefers oxygen, but can grow without

Pure culture

• A culture containing only one species of organism.

END