How can I determine what test would you use if a microbe is using a oxidative or a fermentative metabolism?

How can I determine what test would you use if a microbe is using a oxidative or a fermentative metabolism?

Whether an organism is oxidative or fermentative can be determined by using Hugh and Leifson’s medium, commonly called as OF medium which contain tryptone and bromothymol blue (an indicator). Two tubes are required for interpretation of the OF test.

How do you test for oxidation fermentation?


  1. Obtain pure, isolated colonies from an 18-24 hour culture.
  2. For each test organism, inoculate tubes in duplicate.
  3. Apply sterile mineral oil, sterile melted paraffin, or sterile melted petrolatum to one of each duplicate tubes.
  4. Incubate both tubes aerobically at 35ºC.
  5. Examine tubes daily for colour change.

What does the O F test determine?

The oxidative-fermentative test determines if certain gram-negative rods metabolize glucose by fermentation or aerobic respiration (oxidatively). During the anaerobic process of fermentation, pyruvate is converted to a variety of mixed acids depending on the type of fermentation.

What is the basis of differentiating bacteria with oxidation fermentation test?

What abilities, can one determine, about a microorganism with the OF test? The OF test helps determine whether a microorganism has the ability to oxidize and or ferment a sugar to acid. This test differentiates bacteria on the basis of fermentative or oxidative metabolism of carbohydrates.

What is the difference between oxidation and fermentation?

Oxidation refers to oxidizing of a compound in the presence of enzymes and molecular oxygen while fermentation refers to the transformation of sugars to acids and alcohols in the presence of enzymes and absence of molecular oxygen. So, this is the key difference between oxidation and fermentation.

How is glucose tested for bacteria?

A layer of mineral oil is added to the top of the deep in one of the tubes to create anaerobic conditions. Oil is not added to the other tube to allow for aerobic conditions. The tubes are then incubated for 24–48 hours. If the medium in the anaerobic tube turns yellow, then the bacteria are fermenting glucose.

Which test is used to determine the capability of bacterial culture?

The coagulase test can be used to differentiate between Staphylococcus aureus and other Staphylococcus species. If the coagulase test is positive, the bacteria is likely Staphylococcus aureus; if it is negative, the bacteria is likely Staphylococcus epidermis or Staphylococcus saprophyticus.

Which sugar is used in the methyl red test?


How do you perform a sugar fermentation test?


  1. Weigh and dissolve trypticase, Sodium chloride, and Phenol red in 100 ml distilled water and transfer into conical flasks.
  2. Add 0.5% to 1% of desired carbohydrate into all flasks.
  3. Insert inverted Durham tubes into all tubes, the Durham tubes should be fully filled with broth.
  4. Sterilize at 1150 C for 15 minutes.

What are two common by products of sugar fermentation?

1. Phenol-Red Fermentation Assays a. What are two common by-products of sugar fermentation? Two Common Products: Acid & Gas Phenol-Red-BrothAcid Production: Is indicated by the color change of medium from normal red to yellow and remains red for no acid production.

What are the indications that a carbohydrate is fermented?

Positive: The development of a yellow color in the medium is indicative of a positive carbohydrate fermentation reaction. Negative: Lack of yellow color development is indicative of a negative carbohydrate fermentation reaction. Gas formation is indicated by the appearance of gas bubbles in the Durham tube.

Why is it important to include a pH indicator to detect fermentation products?

The pH indicator helps to differentiate between lactose fermenting and lactose non-fermenter. E coli and other lactose fermenting bacteria give pink-colored colonies in MacConkey agar whereas non-lactose fermenter gram-negative bacilli produce pale yellow colonies.

What are two pH indicators used in microbiology?


Indicator pH AND COLOR
Meta-Cresol Purple (Acid Range) 0.5, red 2.5, yellow
Meta-Cresol Purple (Alkaline Range) 7.4, yellow 9.0, purple
Neutral Red 6.8, red 8.0, yellow
Phenolphthalein 8.3, colorless 10.0, red

What is the Voges Proskauer test used for?

This test is used to determine which fermentation pathway is used to utilize glucose. In the mixed acid fermentation pathway, glucose is fermented and produces several organic acids (lactic, acetic, succinic, and formic acids).

What are the two kinds of fermentation?

There are two types of fermentation: lactic acid fermentation and alcoholic fermentation.

What is the major difference between the 2 types of fermentation?

What are the two types of fermentation? Lactic Acid fermentation produces lactic acid, and alcoholic fermentation produces alcohol and carbon dioxide.

What is fermentation very short answer?

Fermentation is the process in which a substance breaks down into a simpler substance. Microorganisms like yeast and bacteria usually play a role in the fermentation process, creating beer, wine, bread, kimchi, yogurt and other foods.

What is type of respiration?

Three types of respiration include internal, external, and cellular respiration. External respiration is the breathing process. Cellular respiration involves the conversion of food to energy. Aerobic respiration is a cellular respiration that requires oxygen while anaerobic respiration does not.

What is glycolysis class 10th?

Glycolysis is the process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen. Glycolysis is the primary step of cellular respiration.