Legionella Pnuemophilia is a part of the Legionella species of bacteria. It is a thin, single cell, a rod-shaped aerobic bacterium. It can vary in sizes between 2-20 micrometers. This specific bacteria is gram negative and is extremely harmful to humans. It has a cell structure of a typical gram-negative with the outer membrane containing LPS which is toxic towards humans. This bacteria can be found in biofilms, fresh and industrial water systems such as air conditioning units and other similar systems. This bacteria has a genome size of 45  kilobase pairs.  As shown in this picture below, it shows the different genes that are within the bacteria. 

https://science.sciencemag.org/content/sci/305/5692/1966.full.pdf

In the outbreak of 1976 the strain of Legionella Pnuemophilia had a genome size of 3,397,754 base pairs. It has the ability to undergo horizontal gene transfer making it hard for the body’s defense mechanism to kill off the bacteria. In the video below it shows how the bacteria are engulfed by the macrophage cell but it has the ability to grow inside the macrophage and essentially the macrophage dies but the bacteria is still growing.

Some of the essential nutrients needed for the bacteria to grow is the amino acid L-cystine and Ferric iron. 

Some fun facts about this bacteria are that it has a single polar flagellum and has the ability to form long, filamentous flagella on the bacteria after the growth on the surface of sugar.  

https://www.uaz.edu.mx/histo/pathology/ed/ch_9b/c9b_legionella_dieterle.htm

https://www.cdc.gov/legionella/images/materials-bacterium.jpg