Microbes Theoretical result ~~~part 2

Good morning everyone~

7days to go for our practical exam, since not everyone turn up for today's microbiology lab session, i think is always better if i could post some photos about the theoretical result here, which most of them will be included in our practical exam.

 1st of all, sugar fermentation tube.The red color tube on the left indicates that its a alkaline reaction, while the yellow color  on the left indicates that its a acid reaction. Alkaline reaction is usually cause by the deamination of protein, while the acid is cause by sugar fermentation.

A MR-VP is a test to identified the fate of glucose by an organism. The red color in a MR test is caused by phenol red, which turns red in an acidic condition. This is caused by the acidic fermentation of glucose by the bacterium. Vp test in the other hand, is to identified the production of acetylmethylcarbinol from glucose. Usually 2 reagent needed to be added to the tube before a VP result can be observed. 

IN a OF medium, two separate tube is inoculated with the same bacteria. One is left open while the other is sealed by para-film to create a anaerobic environment. The Positive and negative result is shown as the picture above.

Amylase test is a test for the presence of amylase within the bacteria. Amylase is a enzyme that hydrolyze starch into glucose. A iodine reagent is added to the agar, a clear zone around the colony indicates a positive reaction. 

OK. motility test is a test to determine if the bacteria if moving within the agar. A sharp edge of the colonies indicates a negative result.

Gelatinase is an enzyme that liquefy gelatin (a agar like substances), the liquification of agar shows a positive result.

Catalase test will give out bubbles when hydrogen peroxide is added to the colonies. It is usually present in aerobic bacteria.

The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to split indole from the amino acid tryptophan. A pink ring on top of the agar indicates a positive result.

An oxidase is any enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen (O2) as the electron acceptor. A blue color indicates a positive result.  

Mannitol salt agar or MSA is a commonly used growth medium in microbiology.

It contains a high concentration (~7.5%-10%) of salt (NaCl), making it selective forStaphylococci (and Micrococcaceae) since this level of NaCl is inhibitory to most other bacteria. A mannitol fermenting bacteria such as S.aureus will turn the agar into a yellow color.

• Blood agar plate (BAP) Contains mammalian blood (usually sheep or horse), typically at a concentration of 5–10%. BAP are enriched, differential media used to isolate fastidious organisms and detect hemolytic activity. As seen as above, the hemolytic activity  can be classied as alpha beta and gamma, as shown as above.

NOw, S.aureus on a baird parker medium. Black circular colonies.

OK~this is how you classfied ALpha, beta and gamma(non-hemolytic) activity.

Optochin test, only K.pneumonia will be sensitive towards this antibiotic.As shown as the on the right.

Eosin methylene blue (EMB) is a selective stain for Gram-negative bacteria. It is a blend of two stains, eosin and methylene blue in the ratio of 6:1The morphology of Proteus vulgaris and C.coli on EMB agar. 

A more organism on EMB agar.Enterobacter aerogenosa shows black colonies.

MacConkey agar is a culture medium designed to grow Gram-negative bacteria and stain them for lactose fermentation. A lactose fermenter as shown above, turn the agar into a yellow hue.

More bacteria on MacConkey agar. 

Last one, a microscopic view of Bacillus cereus after spore staining. The green color indicates the presences of endospore.

Thx all for the time, good luck in your exam

see you soon~~