Gram Staining Lab Report

Introduction. Christian Gram created the Gram stain technique in 1884 (K. Rudolph [Clemson University, Clemson, SC], personal communication). Gram used tissue in his first attempt with staining (1). The staining of the organisms allowed for the viewing of structure and determining those components by the viewing of the color that appeared after staining the organism (2). The purpose of this experiment was to identify the organism as gram-positive or gram-negative. The first step in the gram staining procedure was to heat fix the smear to the slide to ensure that the organism did not rinse off during the procedure. The second step was to apply crystal violet to the slide for twenty seconds. During this step both gram-negative and gram-positive organisms stained purple in color. After this step

All three smears were viewed under the oil immersion lens (x1000) (3). The use of oil immersion as opposed to lower magnification allowed the organisms to be viewed more clearly and determine certain characteristics of each bacteria due to the color that appeared under the microscope. The gram stain of Micrococcus leuteus (Figure 1) was gram-positive due to the purple color after being stained. The gram stain of Serratia marcescens (Figure 2) was gram-negative due to the pink color after being stained. The gram stain of M. leuteus, S. marcescens and Escherichia coli (Figure 3) was both gram-positive and gram-negative, because S. marcescens and E. coli are gram-negative (4), and M. leuteus is gram-positive. All three of these organisms had a distinct shape as well. Both S. marcescens and E. coli had a rod shape, but M. leuteus had a cocci shape. All three stains were accurate with what they were intended to show. In Figure 2 (S. marcescens), the amount of time the safranin stayed on the slide was important or else it messed up the whole stain, which occurred, leading to having to redo the stain in order to view the correct result, which was a gram-negative organism