What is the Simple Stain?

As you may already know, bacteria are tiny creatures. We cannot see their individual cells with the naked eye; we definitely need equipment to zoom in for a better view. So in a microbiology lab, how can we see the bacteria and learn more about them? One way is by creating a simple stain and viewing it under the microscope. You would clean off a microscope slide, use a metal wire loop or needle to mix water and bacteria on the slide, and let it air dry. When your bacteria looks like a paste or a film, you would hold on to the edge of the slide and quickly pass it over a flame; this is called heat fixing and it helps keep the bacteria on the slide. Next, apply a colorful dye like methylene blue, safranin, or crystal violet; keep it on for one or two minutes, and gently rinse it off with water. Blot your slide dry with bibulous paper. Your slide is ready for the microscope!

If you did the staining procedure correctly, you will see a group of colorful shapes (bacterial cells). So what can we learn from this? Well, a simple stain can tell us some basic identifying characteristics of the cells: their size, their shape, and how they are grouped together. Some bacterial cells are larger, while others look tiny even under the microscope! The three main shapes are cocci (circles), bacilli (rods), and spirilla (you guessed it- spirals). The cells can stand alone, but some common arrangements are pairs (diplo), chains (strepto), or even clusters like a bunch of grapes (staphylo). This is all useful information when you're learning about a species of bacteria! Fun fact: methylene blue, one of the dyes we can use for a simple stain, is also used in medicine. Healthcare professionals can give patients a methylene blue injection to treat a certain problem with their blood.