Purpose: Incestigate if organism can do aerobic respiration or fermentation with glucose as carbon source.

Possible results: The tube with mineral oil layer should not support the growth of obligate aerobic microbes, no color change. Fermenters will have produced organic acids that will result in a drop of pH (color change from green to yellow) The tube without mineral oil layer gives aerobic organisms the chance to perform aerobic respiration; no acids will be produced when glucose is broken down to CO2 and water (yellow color as CO2 lowers the pH). if crack or bubble in agar, it has to be CO2 gas.

purpose: different carbohydrates are offered to investigate the fermentation capabilities of an organism (glucose, lactose, mannatol), with Durham tube to collect gas

Results: the tubes contain pheno red as a pH indicator diye. When fermentation occurs, the acidic endproducts result in a drop of pH, and teh reddish medium turns yellow.

purpose: differentiate Gram-negative bacteria based on detection of butanediol fermentation (neutral endproduct)

result: after incubation  addd VP reagents (Barritt's Reagent). a positive test reveals red color (butanediol is converted to acetoin by the reagents)

purpose:  differentiate Gram-negative enterobacteria by detection of mixed acid fermentation (E. coli) to distinguish from acetylmethylcarbinos (E. aerogenes), a neutral endproduct.

results: after incuubation, Methyl Red indicator dye is added to the brott. It reveals acid by producing a red color. 

purpose: investigate if organism can use citrate as ony carbon source by splitting into pyruvate and oxaloacetate, which are further fermetned to several endproducts and CO2; Differentiate Salmonella and Enterbacter sppl (citrate positive) from other Enterobacteria

results: After incubation, apositive test will look blue due to the change in pH (increased) because of ammonia productionl

purpose: test for anaerobic respiration with nitrate as terminal electron acceptor. nitrate willbe reduced to Nitrite, N2O or N2.

results: Reduction of Nitrate to Nitrite is revealed by adding Reagent A (sulfanilic acid), resulting in a red color if nitrite is present.

If the test is negative for nitrite, check with zink dust if nitrate is gone (that would mean that nitrite was further reduced to N2O or N2). if nitrate was not reduced the zinc racts with nitrate, revealing a red color (neagative test for nitrate reduction).

purpose: tests for glucose and lactose fermentation, cysteine catabolixm (H2S) production

results: The phenol red pH indicator dye reveals a: yellow butt  = only glucose has been used; acidic end products accumulate. 

yellow entire = lactose and glucose have been used. pink = proteins have been fermented instead of sugars and the pH increased due to ammonia production (pink color)

black color = develops when H2S is released from the degradation of the amino acid cysteine and the production of FEs (black). If sulfate would be in the medium, the black color can also indicate anaerobic respiration with Sulfate as the terminal electron acceptor

purpose: tests for: the degradation of cysteine (H2S production); the degradation of amino acid tryptophan (Indole production); and motility (growth away from stab line in semisolid medium)

results: H2S will be detected when it reacts with iron salts to form FeS (as in KIA); tryptophan degradation will be confirmed by testing for the Kovac's reagent; Motility can be observed by looking at the stabline.

purpose: tests for degradation of lactose, proteins and other molecules peresent in the milk. Litmus works as pH indicator.

results:

Pink = lactose is fermented; acidic end products decrease the pH

purple/blue or transluscent: proteins are digested, the released ammonia increases the pH (basic) coagulation might occure as well

white: Litmus dye can be used as an electron acceptor during fermentation; A drop in oxygen because of aerobic respiration might also result in a white tube.

purpose: tests for the presence of urease. Urea is broken down to ammonia

result:

Pink: positive for the presence of urease; Use of urea results in an increase of pH (ammonia production)