Simple & Differential Staining

SIMPLE STAINING:

Staining is the process by which microorganisms are colored by stain or dye.  Simple staining is the one that contains only a single staining agent i.e. a single dye dissolved in a solvent. It is important because of its simplicity and ease of use. This procedure involves applying stain or dye to microorganisms in single application only. In this staining process, smear is covered with stain for a definite period of time, then the excess stain is washed off and blots the slide dry. It helps to study the shape, size and arrangement of bacteria. Mostly basic dyes are used in simple staining. Some common examples are Methylene blue, Crystal violet etc. 

DIFFERENTIAL STAINING: 

Differential staining is one that contains more than one dye i.e. two or more stains. Depending on the staining technique, the dyes can be applied separately or they can be mixed and applied in one solution. This staining technique differentiates bacterial cells or parts of cells visible. Gram staining and acid fast staining are two differential staining that separates microorganisms into groups. Gram staining divides bacteria into Gram positive and Gram negative whereas acid fast staining divides bacteria into acid fast and non acid fast. This technique is also used to visualize structures like spore, flagella, nucleus etc.