Experiment 2 routine cultivation of bacteria The cultivation of bacteria (1)
Dec 24, 2015
Experiment 2
routine cultivation of bacteria
The cultivation of bacteria (1)
Contents1. Media for routine cultivation of bacteria
2. Techniques for bacterial cultivation and
inoculation
3. Growth characteristics of bacteria on/in different
media
4. Metabolic activities of bacteria
5. The physical effect on bacteria and commonly
used sterilizers
1. Media for routine cultivation of bacteria
Media--- The basic ingredients of media
include carbon source 、 nitrogen source、 inorganic salt 、 growth factor and
distilled water etc.
Classification of culture media
According to function, in general, media can be classified five types:
1. basal medium ( agar plate medium) 2. nutrient medium (blood agar plate medium) 3. selective medium 4. differential medium 5. anaerobic medium.
According to physical properties, media can be classified three types:
1. solid medium ( 1.5~ 2.5% of agar)
agar plate /slant medium
2. semi-solid medium (0.3~ 0.5% of agar)
3. liquid medium
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2. Techniques for bacterial inoculation
Bacterial inoculation is a basic technique of microbiology. The operation must be under sterile condition.
1) isolation cultivation
2) pure cultivation
• 1) Isolation cultivation• streak a bacterial culture on a nutrient agar
plate to separate the individual bacterial cells, each isolated cell will develop into a pure colony after incubation.
• continuous streak method
• quadrant streak dilution methodmethod
2) Pure cultivation transfer a single colony from agar plate or a
pure slant culture to liquid medium, slant or semisolid medium to get a pure culture.
subculture into liquid medium
subculture into agar slant/plate
subculture into agar deep tube (semi-solid)
3. Phenomena of bacterial growth
on agar plate (on blood agar plate)
in liquid medium
in semi-solid medium
1) on agar plate
observe the isolated colony on the surface of nutrient agar plate; note size, shape, elevation, margin, surface, transparency and pigment (color of colony).
on agar plate -- colonycolony
Note:
Size 大小
Shape 形状
Elevation 突起
Margin 边缘
Surface 表面
Transparency 透明度
Pigment 色素
on blood agar plate
observe hemolysis (complete and incomplete)
phenomena around colony.
3) in liquid medium
three growth phenomena will be seen: surface growth pellicle 表面生长 uniformly turbid 均匀混浊生长 sediment in bottom 沉淀生长
In liquid mediumsurface growth pellicle uniformly turbid sediment in bottom
4) in semi-solid medium nonmotile organism
motile organism
4. Metabolic Products and Biochemical Testing
Carbohydrate Fermentation Test
溴甲酚紫【 pH 5( 黄 ) - pH7( 紫 ) 】
Methyl Red (MR) Test
Voges-Proskauer (VP) Test
Indole Test
• Citrate utilization test
I M Vi C test E.coli + + - - E.Aerogenes - - + +
Hydrogen Sulfide (H2S ) Production
sulfur amino acid
sulfur inorganic compoundH2S
Pb2+
Fe2+
PbS
FeS( black )
Urease Test
5. The physical effect on bacteria and
commonly used sterilizers 1) Physical factor:
dry 、 moist 、 ultraviolet 、 ultrasonic wave 2) Commonly used sterilizers:
autoclave
dry-air oven
bacteriological filters
Experiment manipulation
1. Continuous streak method or quadrant streak method strain: S.aureus or E.coli
one piece of plate/person
2. Observe phenomena of bacterial growth on agar plate in liquid medium in semi-solid medium
Experiment report1. Continuous streak method or quadrant streak
method:
principle
procedure
result: describe the characteristics of colony
analysis
2. Draw phenomena of bacterial growth