Biofilms Lab Report

Introduction and Experimental Objectives

The aim of this experiment was to understand the function and formation of biofilms in bacteria and explore their role while infection occurs in the host. Biofilms have become more prevalent in hospitals and adhere to instruments used in medical procedures and even dry objects in hospitals, for example hospital curtains. The bacteria that form these biofilms can be dangerous to humans, for example Staphylococcus aureus, a methicillin-resistant bacteria. [1]

Biofilms are a group of microbial cells that are surrounded by a polymeric matrix including proteoglycans, peptidoglycans and polysaccharides located outside the cell that can allow the growth of the pathogens to slow down, allow them to attach to surfaces, defend them from the immune system and enable the nutrition of the pathogen.

In this experiment, to stain the biofilm, Crystal Violet was used as biofilms contain peptidoglycans in their matrix. Peptidoglycans pick up crystal violet stain strongly and so when a strong biofilm is formed, crystal violet will stain darkly due to the many peptidoglycans present in the cell. On the

As the strains used are the same as in the first test. A bio-film forming strain was identified in strain one and two from the initial experiment, and no biofilm forming strains were found in the third strain. This was reflected in this experiment. The first strain formed a black streak on the agar, representing the presence of a biofilm, which was expected from the previous experiment. Another expected result was the presence of the red streak in the red agar for the third strain suggesting no biofilm was present. The second strain formed a dark red streak, however, which was unexpected as a dark streak indicating a biofilm was expected from the initial experiment. However, the dark red streak indicated some biofilm was present, although not as much as in the first