FOOD MICROBIOLOGY
MICROORGANISMS IN FOOD
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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to observe level of broth
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to detect pH of the broth
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to detect gas produced by micro organisms.
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none of the above
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Detailed explanation-1: -Durham tubes are used in microbiology to detect production of gas by microorganisms. They are simply smaller test tubes inserted upside down in another test tube so they are freely movable.
Detailed explanation-2: -Phenol Red Broths (aka Durham Tube Sugar Fermentations): Dextrose, Lactose, Sucrose. Purpose: To distinguish carbohydrate fermenters from non-fermenters, to detect and distinguish utilization of specific carbohydrates by the products formed.
Detailed explanation-3: -Organisms that are capable of converting pyruvate to formic acid and formic acid to H2(g) and CO2 (g), via the action of the enzyme formic hydrogen lyase, emit gas. This gas is trapped in the Durham tube and appears as a bubble at the top of the tube.