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GELATIN HYDROLYSIS TEST
Purpose :
Determination of the ability of the
organisms to digest (hydrolyse) gelatin, as a
sole source of protein by activity of the
gelatinase enzyme.
Materials :
1. Aeromonas hydrophila on BA.
2. Escherichia coli
on BA.
GELATIN HYDROLYSIS TEST
Media & Reagents :
1. Gelatin agar plates.
2. Acid mercuric chloride solution
Method :
1. Inoculate by cross streaking of 1 & 2
on each of gelatin plates.
2. Incubate at 370C for 24 hrs.
GELATIN HYDROLYSIS TEST
Interpretation :
Before reading, flood the cultures with
acid mercuric chloride, leaving for 5-10 minutes.
Positive : clear zone around colony.
Negative : no clear zone around colony.
GELATIN HYDROLYSIS TEST
Positive : clear zone around colony.
Negative : no clear zone around colony.
STARCH HYDROLYSIS TEST
Purpose :
To determine the ability of the organism
to produce amylase enzyme which digests or
hydrolyses starch.
Materials :
1. Bacillus subtilis
2. Escherichia coli
on BA.
on BA.
STARCH HYDROLYSIS TEST
Media & Reagents :
1. Two starch agar plates.
2. Lugol’s iodine solution.
Method :
1. Inoculate 1 & 2 on each of starch
agar plate.
2. Incubate at 370C for 24 hrs.
STARCH HYDROLYSIS TEST
Interpretation :
Flood the cultures with Lugol’s solution,
and remain for 5-10 minutes.
Positive : clear zone around colonies.
Negative : no clear zone around colonies.
Remark : Some orgamisms, produce weak
reaction, clear zone present
under colonies.
STARCH HYDROLYSIS TEST
Positive : clear zone around colonies.
Negative : no clear zone around colonies.
CASEIN DIGESTION TEST
Purpose :
To determine the ability of organisms
to produce caseinase (proteinase)
enzyme which digest casein.
Materials :
1. Aeromonas hydrophila on BA.
2. Escherichia coli
on BA.
CASEIN DIGESTION TEST
Media & Reagents :
Two casein agar plates.
Method :
1. Spot inoculation of 1 & 2 on each of
casein agar plates.
2. Incubate at 370C for 24 hrs.
CASEIN DIGESTION TEST
Interpretation :
Positive : clear zone around colonies.
Negative : no clear zone around
colonies.
LECITHOVITELLIN REACTION (LV)
Lecithinase & Lipase activities
Purpose :
To determine the ability of the
organisms to produce lecithinase or/and
lipase. The enzymes are demonstrated by
cultivation on egg yolk agar.
LV REACTION
Lecithinase & Lipase activities
Materials :
1. Bacillus cereus
on BA.
2. Aeromonas hydrophila
on BA.
3. Bacillus subtilis
on BA.
Media & Reagents :
Two egg yolk agar plates.
LV REACTION
Lecithinase & Lipase activities
Method :
of L-V
1. Spot inoculate 1, 2 & 3 on each
agar plate.
2. Incubate at 370C for 24 hrs.
Reaction :
Zone of opalescent around colony
indicated lecithinase activity against
lecithovitellin in egg yolk and precipitation
around colony indicated lipase activity.