Pseudomonas aeruginosa is one of the most distinctive organisms in the lab. It glistens like silver as it spreads over the plate. The smell from this organism is overpowering but strangely incongruent. Some people smell grapes and some smell.
Pseudomonas aeruginosa on blood agar. Note the metallic sheen and ground glass appearance. Depending on who you are it can smell like grapes, new shoes, or dirt. To me it smells like grapes. One of the friendlier smells in the micro lab.
In a high-magnification scanning electron micrograph of a Pseudomonas aeruginosa biofilm (left), the individual rod-shaped bacteria are interlinked by hairlike structures called pili. Bacillus bacteria secrete an extracellular matrix that encases the cells and helps them form a more structured community (right).
An electron micrograph shows round Staphylococcus aureus bacteria, bound by a biofilm, on the surface of an indwelling catheter. Biofilms shield bacteria from antibiotic attacks and are responsible for most hospital infections.