**Abstract**

*Legionella pneumophila* (*L. pneumophila*) is the causative agent of Legionnaires' disease. Transmission to humans is mediated via inhalation of contaminated water droplets. *L. pneumophila* is widely distributed in man-made water systems, multiple species of protozoa, and nematodes. *L. pneumophila* persist within multi-species biofilms that cover surfaces within water systems. Virulence, spread, and resistance to biocides are associated with survival of *L. pneumophila* within multi-organismal biofilm. Outbreaks of Legionellosis are correlated with the existence of *L. pneumophila* in biofilms, even after the intensive chemical and physical treatments. Several factors negatively or positively modulate the persistence of *L. pneumophila* within the microbial consortium-containing *L. pneumophila*. Biofilm-forming *L. pneumophila* continue to be a public health and economic burden and directly influence the medical and industrial sectors. Diagnosis and hospitalization of patients and prevention protocols cost governments billions of dollars. Dissecting the biological and environmental factors that promote the persistence and physiological adaptation in biofilms can be fundamental to eliminating and preventing the transmission of *L. pneumophila*. Herein, we review different factors that promote persistence of *L. pneumophila* within the biofilm consortium, survival strategies used by the bacteria within biofilm community, gene regulation, and finally challenges associated with biofilm resistance to biocides and *anti-Legionella* treatments.

**Keywords:** *legionella pneumophila*, biofilm, Legionellosis, protozoa, *Caenorhabditis elegans*
