Swarmer cell differentiation in Proteus mirabilis

• Published in: Environmental microbiology Vol. 7; no. 8; pp. 1065 - 1073
• Main Author: Rather, Philip N.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.08.2005
• Subjects: Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biofilms - growth & development; Gene Expression Regulation, Bacterial; Humans; Mice; Movement; Proteus Infections - microbiology; Proteus mirabilis - genetics; Proteus mirabilis - pathogenicity; Proteus mirabilis - physiology; Virulence
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/j.1462-2920.2005.00806.x

Summary Under the appropriate environmental conditions, the Gram‐negative bacterium Proteus mirabilis undergoes a remarkable differentiation to form a distinct cell type called a swarmer cell. The swarmer cell is characterized by a 20‐ to 40‐fold increase in both cell length and the number of flagella per cell. Environmental conditions required for swarmer cell differentiation include: surface contact, inhibition of flagellar rotation, a sufficient cell density and cell‐to‐cell signalling. The differentiated swarmer cell is then able to carry out a highly ordered population migration termed swarming. Genetic analysis of the swarming process has revealed that a large variety of distinct loci are required for this differentiation including: genes involved in regulation, lipopolysaccharide and peptidoglycan synthesis, cell division, ATP production, putrescine biosynthesis, proteolysis and cell shape determination. The process of swarming is important medically because the expression of virulence genes and the ability to invade cells are coupled to the differentiated swarmer cell. In this review, the genetic and environmental requirements for swarmer cell differentiation will be outlined. In addition, the role  of  the  differentiated  swarmer  cell  in  virulence and its possible role in biofilm formation will be discussed.