Microaerophilic

Microaerophilic bacteria typically require O2 concentrations that are less than what is achieved in a candle jar. Therefore, these bacteria are often incubated in a gastight jar with a special disposable packet containing chemicals that react to generate hydrogen and carbon dioxide. A catalyst in the jar speeds up

Figure 4.7 MacConkey Agar This complex medium is differential for lactose fermentation and selective for Gram-negative rods that typically reside in the intestine. Bacteria that ferment the sugar produce acid, which turns the pH indicator pink, resulting in pink colonies. Lactose-negative colonies are tan or colorless.The bile salts and dyes in the media inhibit all but certain Gram-negative rods.

Figure 4.7 MacConkey Agar This complex medium is differential for lactose fermentation and selective for Gram-negative rods that typically reside in the intestine. Bacteria that ferment the sugar produce acid, which turns the pH indicator pink, resulting in pink colonies. Lactose-negative colonies are tan or colorless.The bile salts and dyes in the media inhibit all but certain Gram-negative rods.

Nester-Anderson-Roberts: I I. Life and Death of I 4. Dynamics of Prokaryotic I I © The McGraw-Hill

Microbiology, A Human Microorganisms Growth Companies, 2003

Perspective, Fourth Edition

Screw clamp

Gasket

Pellet catalyst

Hydrogen gas generator

Petri dishes

Figure 4.8 Anaerobe Jar The hydrogen released from the generator combines with any O2 to form water, thereby producing an anaerobic environment.

Screw clamp

Gasket

Pellet catalyst

Hydrogen gas generator

Petri dishes

Figure 4.8 Anaerobe Jar The hydrogen released from the generator combines with any O2 to form water, thereby producing an anaerobic environment.

the reaction of hydrogen with atmospheric oxygen to form water. The amount of hydrogen generated, however, is not enough to combine with all of the O2, so that conditions do not become anaerobic.

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