2.5.1 Materials Required
l
12-h old broth culture.
l
Hanging drop (cavity) slide.
l
Cover slips.
l
Vaseline/Petroleum jelly.
2.5.2 Procedure
1. Take a fresh hanging drop slide and show it in flame. Gently
place it on the table with the depression uppermost.
2. Smudge a little Vaseline or petroleum jelly completely on the
cavity of the slide.
3. Take a fresh and clean cover slip and smudge petroleum jelly on
each of the four corners of the cover slip.
4. Gently keep the cover slip on a clean paper with the petroleum
jelly side up.
5. Take a whole loop of culture in the center of the cover slip.
6. Gently place the depression slide on to the cover slip, so that
the cavity faces down and the suspension is covered by the
depression.
7. Push down the slide softly to make a secure betwixt the cover
slip and the slide.
8. Hold up the preparation and quickly turn the hanging drop
preparation cover slip up so that the culture drop is suspended.
9. Visualize the preparation under low- to high-power objective.
3 Biochemical Characterization
Xenorhabdus sp. and Photorhabdus sp. are verified for their positive
or negative response to diverse biochemical tests on the basis of
Bergey’s manual of determinative bacteriology [202].
3.1 Catalase Test
The enzyme catalase mediates the catabolism of hydrogen peroxide
into oxygen and water. The presence of the enzyme in a bacterial
isolate is apparent when a small inoculum is familiarized into hydrogen peroxide, and the swift amplification of oxygen bubbles occur.
3.1.1 Materials Required
l
Hydrogen peroxide (H 2 O 2 ).
l
Organisms: Bacteria Xenorhabdus and Photorhabdus.
l
Test tube.
l
Sterile wooden stick/glass rod.
l
Glass slide.
122
Laboratory Techniques for Symbiotic Bacteria
l
12-h old broth culture.
l
Hanging drop (cavity) slide.
l
Cover slips.
l
Vaseline/Petroleum jelly.
2.5.2 Procedure
1. Take a fresh hanging drop slide and show it in flame. Gently
place it on the table with the depression uppermost.
2. Smudge a little Vaseline or petroleum jelly completely on the
cavity of the slide.
3. Take a fresh and clean cover slip and smudge petroleum jelly on
each of the four corners of the cover slip.
4. Gently keep the cover slip on a clean paper with the petroleum
jelly side up.
5. Take a whole loop of culture in the center of the cover slip.
6. Gently place the depression slide on to the cover slip, so that
the cavity faces down and the suspension is covered by the
depression.
7. Push down the slide softly to make a secure betwixt the cover
slip and the slide.
8. Hold up the preparation and quickly turn the hanging drop
preparation cover slip up so that the culture drop is suspended.
9. Visualize the preparation under low- to high-power objective.
3 Biochemical Characterization
Xenorhabdus sp. and Photorhabdus sp. are verified for their positive
or negative response to diverse biochemical tests on the basis of
Bergey’s manual of determinative bacteriology [202].
3.1 Catalase Test
The enzyme catalase mediates the catabolism of hydrogen peroxide
into oxygen and water. The presence of the enzyme in a bacterial
isolate is apparent when a small inoculum is familiarized into hydrogen peroxide, and the swift amplification of oxygen bubbles occur.
3.1.1 Materials Required
l
Hydrogen peroxide (H 2 O 2 ).
l
Organisms: Bacteria Xenorhabdus and Photorhabdus.
l
Test tube.
l
Sterile wooden stick/glass rod.
l
Glass slide.
122
Laboratory Techniques for Symbiotic Bacteria