There has been considerable discussion regarding the environmental life cycle of and its virulence potential in natural and man-made water systems. On the other hand, the bacterium's morphogenetic mechanisms within host cells (amoeba and macrophages) have been well documented and are linked to its ability to transition from a non-virulent, replicative state to an infectious, transmissive state. Although the morphogenetic mechanisms associated with the formation and detachment of the biofilm have also been described, the capacity of the bacteria to multiply extracellularly is not generally accepted. However, several studies have shown genetic pathways within the biofilm that resemble intracellular mechanisms. Understanding the functionality of cells within a biofilm is fundamental for assessing the ecology and evaluating how the biofilm architecture influences survival and persistence in water systems. This manuscript provides an overview of the biphasic cycle of and its implications in associated intracellular mechanisms in amoeba. It also examines the molecular pathways and gene regulation involved in biofilm formation and dissemination. A holistic analysis of the transcriptional activities in biofilms is provided, combining the information of intracellular mechanisms in a comprehensive outline. Furthermore, this review discusses the techniques that can be used to study the morphogenetic states of the bacteria within biofilms, at the single cell and population levels.
