Pseudomonas fluorescens bacterium, coloured transmission electron micrograph (TEM). P. fluorescens is a common gram-negative rod-shaped non-invasive and opportunistic pathogen that rarely infects healthy individuals. It has multiple flagella (yellow) that it uses for locomotion. It is found in soil and water and is an obligate aerobe. Several strains have developed antibiotic resistance. Magnification: x15,300 when printed at 10 centimetres tall.