Bacterial Staining



Hi and welcome, this week practical is about bacterial staining. . Our objectives are to study the properties and to divide microorganisms into specif groups for diagnostic purposes, biological stains and staining procedures.There are two stains which is acidic stains are anionic, which means that, on ionization of the stain, while basic stains are cationic, because on ionization the chromogen portion exhibits a positive charge. This week we going to do two staining which is simple staining and negative staining. In simple staining, the bacterial smear is stained with a single reagent, which produces a distinctive contrast between the organisms and its background. For negative staining, it requires the use of acidic stain such as India ink or nigrosin. For this we used nigrosin. The acidic stain with its negatively charge chromogen, will not penetrate the cells because of the negative charge
on the surface of bacteria.


Simple staining
We use three reagents. Methylene blue, crystal violet and carbon fuchsin.

The procedure is very simple, Firstly, we need to placed the slide on the staining tray and flood it in the reagents. Allow it for 1 to 2 minutes. Then, gently wash it with tap water. Keep it dry. Repeat with the same step with different reagent.

Negative staining
Reagent that we used is nigrosin

Firstly, we placed a drop of nigrosin at the end of slide. Place a loopful of the inoculum into the drop of stain and mix it. Then place a slide against the drop suspended and spread it along the edge of the appiled slide. Then push the slide away from the previously spread drop of suspended organisms. Air-dry the slide.

Simple staining & negative staining


After we done it, the next day we observed the slide that we done. We observed its shape ,size ,arrangement and its color. Below are some the picture that I takes


B. cereus in carbol fuchsin

We can see above that the B.cereus have rod shaped. The arrangement have diplobacillus and streptobacillus




E. coli in carbol fuchsin


S. aureus in carbol fuchsin


E. coli have a rod shaped, while S. aureus have staphylococcus shape. All the slide that flood with carbol fuchsin all produce red or pink color.


That is all from me. I will update more next week about our next experiments. Goodbye. 




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