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Cultivation, Reproduction, and Growth of Bacteria

NUTRITIONAL REQUIREMENTS (Essential for growth and function)

1.)    Energy source

Radiant Energy (light)--phototrophs

Chemical compounds (oxidation reactions)--chemotrophs

2.)    Carbon source

Carbon dioxide--autotrophs

            Photoautotrophs--light/carbon dioxide

            Chemoautotrophs--compounds/carbon dioxide

Carbohydrates (organic compounds)--heterotrophs

3.)    Nitrogen source

Plants--nitrogen salts

Animals--proteins (amino acids) and peptides

Bacteria--atmospheric nitrogen

                 inorganic nitrogen (sodium nitrate)

                 organic nitrogen compounds

4.)    Sulfur and Phosphorus

Sulfur

            Animals--organic sulfur compounds

            Plants--inorganic sulfur compounds

            Bacteria--organic sulfur compounds

                              inorganic sulfur compounds

                              elemental sulfur

Phosphorus--phosphorus salts--phosphoric acids

5.)    Metallic elements--trace

Na, K, Ca, Mg, Mn, Fe, Zn, Cu, & Co

6.)    Vitamins--function in coenzyme/cofactor production

Synthesis of all vitamins

Some must by furnished to the bacteria in medium

7.)    Water--nutrients must be in solution

NUTRITIONAL TYPES OF BACTERIA

            Phototroph

                        Autotroph--light/carbon dioxide

                        Heterotroph--light/organic compounds

            Chemotroph

                        Autotroph--inorganic compound/carbon dioxide

                        Heterotroph--organic compound/organic compound

BACTERIOLOGICAL MEDIA

            Types of Media--Agar, peptones, meat & yeast extracts

                        Nutrient Broth and Nutrient Agar--common heterotrophs

                                    yeast extracts provide B vitamins

                                    n.b.-beef extract (3 g.)

                                           peptone (5 g.)

                                           water  (1000 ml.)

                                    n.a.-n.b. & agar (15 g.)

                        Ready-mades

           

 

Preparation

1.)    dissolve media in appropriate volume of water

2.)    adjust pH

3.)    dispense into suitable containers

4.)    sterilize/autoclave

Physical conditions required for Growth

                        Temperature

                                    Psychrophiles  (0 to 30 C)   15 C

                                    Mesophiles  (25 to 40 C)

                                    Themophiles  (50 C and higher)  55 C

                                    Optimal growth temperature

                        Gaseous Atmosphere

                                    Oxygen responses

                                                Aerobic

                                                Anaerobic

                                                Facultatively anaerobic (both of above)

                                                Microaerophilic (low oxygen conc.)

                        Acidity or Alkalinity (pH)

                                    Buffers--phosphate salts

                        Miscellaneous conditions

                                    Energy source

                                    Osmotic pressure (halophiles--obligate & fac.)

            Choice of Media and Conditions of Incubation

                        fastidious--nonfastidious

REPRODUCTION OF BACTERIA

            Transverse binary fission

1)      cell elongation

2)      invagination of cell wall and distribution of nuclear material

3)      formation of transverse cell wall and distribution of cellular material

4)      seperation into two new daughter cells

Growth--Synchronous culture experiments

            Concept of bacterial growth

                        geometrical progression--exponential growth

                        generation time

            Growth cycle / curve

                        Lag phase

                        Logrithmic or exponential phase--balanced growth

                        Stationary phase

                        Decline or Death phase

            Quantitative measurement of growth

                        microscopic count

                        plate count

                        membrane or molecular filter

                        turbidimetric measurement

                        nitrogen determination

                        weight determination

                        measurement of biochemical activity

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