What are the staining characteristics of bacteria?
Since bacteria are prokaryotes, they lack a lot of detail that you may be familiar with in working with nucleated cells. Also since they are so small, any detail is very hard to appreciate. So basically with routine stain preparations, bacteria are going to look very uniform and stain the same color throughout the cytoplasm. But there are some special stain techniques that are very important in classifying bacteria, namely the Gram stain and the acid fast stain. What is the Gram stain? The Gram stain traditionally serves as part of a major classification scheme for all bacteria, as either Gram positive or Gram negative. With Gram staining, a species of bacteria will stain either red (pink) or violet (blue/purple). There are four steps to the Gram stain technique and the materials used are crystal violet, iodine, alcohol based decolorizer, and a red dye, such as safranin red. Overview of Gram stain First a thin film of bacteria are placed on a slide and dried. The slide is heat fixed by
