applying a simple stain to a bacterial culture is a technique that is used for
examining the size shape and arrangement of a specimen it uses a dye to stain the
cells making them easier to see under a microscope in this experiment we will
demonstrate the steps for applying a simple stain to the bacterial organism
Staphylococcus start with a clean microscope slide use a china marking
pencil to label one end of the slide with a specimen name draw a circle in
the center of the slide because we're using Staphylococcus from a solid source
we'll draw a circle about the size of a nickel turn the slide over so that the
circle is on the bottom this will prevent the marking from mixing in with
the sample add a drop of distilled water to the slide sterilize an inoculating
loop by passing it through the flame of a Bunsen burner
when the loop is cool touch the bacterial colony and transfer the
bacteria to the slide use the loop to mix the cells and the water spread the
mixture to completely fill the circle
allow the slide to air dry at room temperature the time will vary depending
on the size of the smear you will know the slide is dry when you see a thin
white haze next heat fix the slide by passing it through a flame three times
flood the slide with safranin safranin is a biological stain that will die the
bacterial cells red making them easier to see under a microscope be sure to
fill the entire circle with the dye
leave the stain on for 30 seconds gently wash the slide with distilled water
drain off any excess water use Bibulus paper to gently blot the slide dry after
the slide has completely air dried the smear will look like a thin red haze
here you can see the difference the slide on the left is our stain slide a
slide on the right is unstained load the stain slide onto the microscope stage
always start with the lowest power objective use the coarse and fine
adjustments to bring the bacteria into focus
since this is a bacterial specimen we must observe it under oil immersion
the Staphylococcus cells look like small red balls sketch the image in your lab
notebook now you're ready to go into the lab and perform a simple stain