Practical seminar 5/05
capsules, sporulation
Spores - endospores
• Some pathogenic Gram positive bacteria from genus
Bacillus and Clostridium - can forme spores. Their
localisation is diagnostic
• In unfavorable conditions the vegetative cell forms
one spore (sporulation, dormant phase of life cycle) –
formation of multiple layers – coat – dipicolin acid
and Ca
• Resistance to environmental extreme conditions
• Germination – return to vegetative phase of lifecycle
– breaking of coat, water intake
• Activation – 1st step of germination – changes in
environmental condition – mild temperature, alanin
Wirtz Conklin
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Differencial staining form spores
Spore forming bacteria – red
Spores – green
Susspension dried on the air, heat fixed and
stained with 5% malachit green. Heating untill
evaporation for 3-6 minutes. Rins under water
flow, add 0,5% water solution of safraninfor
counter staining (30 sec.) Rinse with water, dry
and read in 400-1000 times magnification
Bacillus cereus - spóry
Burri´s method for capsule
detection
Prepare the suspension of the colony and
destilled water on the slide
Add one drop of inkand make a thin smear
Dry on air and fix with heat
Counterstain with crystalin violte , rinse very
carefully with water , let dry on air and read
with immersion
Capsules
• Extracellular structures overlying the cell wall
• Polysaccharide ( exception B. antracis – polypeptid)
• Tool of virulence – antifagocytic properties, act as
adhesin
• Some bacteria can be present in form of encapsulated
and nonencapsulated strains
• Strains loose capsule in older cultures or can gain it by
transformation from encapsulated strains when
cultivated together
Hemofilus influenzae b acc.Burri
• On black smear capsules are represented by
uncolored space in forme of rod
In the white space
the cristalin violet
counterstained rods
can be indentified - blue
Encapsulated rod - scheme