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Microbiology

AMYLASE TEST (STARCH HYDROLYSIS)

Dayyal Dg.
By Dayyal Dg.
Published: Tuesday, 04 April 2017
Updated: Tuesday, 04 April 2017 18:20
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Figure: Two species are inoculated onto a starch plate and incubated at 30°C until growth is seen (plate on the left). The petri dish is then flooded with an iodine solution and photograph taken after 10 minutes (plate on right). Amylase positiv species shows a clearing halo around the growth (top line of growth). Amylase negative species does not have this clear halo (bottom line of growth).
Figure: Two species are inoculated onto a starch plate and incubated at 30°C until growth is seen (plate on the left). The petri dish is then flooded with an iodine solution and photograph taken after 10 minutes (plate on right). Amylase positiv species shows a clearing halo around the growth (top line of growth). Amylase negative species does not have this clear halo (bottom line of growth). © BioScience.pk

Objective: To determine if the organism is capable of breaking down starch into maltose through the activity of the extra-cellular α-amylase enzyme.

Test procedure
1. Use a sterile swab or a sterile loop to pick a few colonies from your pure culture plate. Streak a starch plate in the form of a line across the width of the plate. Several cultures can be tested on a single agar plate, each represented by a line or the plate may be divided into four quadrants (pie plate) for this purpose.
2. Incubate plate at 37 °C for 48 hours.
3. Add 2-3 drops of 10% iodine solution directly onto the edge of colonies. Wait 10-15 minutes and record the results.

Amylase Test

• Interpretation:
-- Positive test ("+"): The medium will turn dark. However, areas surrounding isolated colonies where starch has been hydrolyzed by amylase will appear clear.
-- Negative test ("-"): The medium will be colored dark, right up to the edge of isolated colonies.

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AMYLASE TEST (STARCH HYDROLYSIS)
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