Complete Review As the resident microbiologist in the imaging core for the university, it is your job to aid the researchers in preparing photographic data and representative figures for publication. You prepare samples for staining and set up the computers and microscopes to photograph and measure the cells. Due to their small size and the fact that most do not contain any pigments, these cells must be colorized
using chemicals or compounds. Generally, dyes or charged stains are used to colorize the cell and allow for visualization. Before bacterial cells may be stained, they have to be "fixed" to the glass slide or they will be rinsed away with the stain. To "fix" a bacterial cell to a glass slide, a drop of the culture must be air dried and then heated in the flame of a Bunsen burner to drive off any water molecules that may be trapped between the bacterial cell and the surface of the glass. The
heating also denatures some proteins and sugars on the cell surface that will stick to the surface of the glass and aid in retention of the bacterial cells during any wash steps, some of which may be stringent and would wash away any cells not adhered to the glass. Following the fixation of the bacteria to a glass slide, the cells may then be stained using many different methods and dyes. Simple stains are used for visualization of the cells' general morphology without any distinction between
possible species present. Simple stains are composed of a single dye, such as crystal violet, safranin, or methylene blue and are labeled as "simple" because after soaking the smear in the dye for 30-60 seconds the slide is rinsed off with water.
