Differentiation of Serratia marcescens 274 into swimmer and swarmer cells

Abstract

We describe a new sensory response in the enteric bacterium Serratia marcescens. When grown in liquid media, the bacteria were short rods with one to two flagella and displayed classical swimming behavior. Upon transfer to a solid surface (0.7 to 0.8% agar medium), the bacteria underwent a dramatic change of form. They ceased septation, elongated, and expressed numerous (10 to 100) flagella that covered the lateral sides of the cells. The bacteria now displayed a different form of locomotion-swarming-which allowed them to rapidly move over the top of the solid surface. The differentiation to either swimmer or swarmer cells could be reversed by growth on solid or liquid medium, respectively. To identify conditions that influence this differentiation, the growth environment of S. marcescens was manipulated extensively. The swarming response was monitored by visual and microscopic observation of cell movement on solid surfaces, by immunofluorescent labeling followed by microscopic observation for the presence of elongated, profusely flagellated cells, as well as by estimation of induction of flagellin protein, using Western immunoblot analysis. Conditions that imposed a physical constraint on bacterial movement, such as solid or viscous media, were the most efficient at inducing the swarming response. No chemical constituent of the medium that might contribute to the response could be identified, although the existence of such a component cannot be ruled out. Both swimmer and swarmer cells had flagellin proteins of identical molecular weight, which produced similar proteolysis patterns upon digestion with trypsin. Combined with an earlier demonstration of a single flagellin-encoding gene in S. marcescens (R. M. Harshey, G. Estepa, and H. Yanagi, Gene 79:1-8, 1989), our results suggest that the same protein is a component of both swimmer and swarmer cell flagella. Thus, in response to a physical signal, a single flagellin gene must be differentially regulated. We discuss possible mechanisms for sensing such a signal.

Inorganic polyphosphate is needed for swimming, swarming, and twitching motilities of Pseudomonas aeruginosa

“…Swarming, another form of flagella-dependent surface motility, has been described in Proteus mirabilis, Vibrio parahaemolyticus, and Serratia marcescens (6,27,33), and more recently in E. coli, S. typhimurium, Serratia liquefaciens, Yersinia enterocolitica, and Pseudomonas syringae (34)(35)(36)(37). We have now discovered that under appropriate conditions a similar swarming response occurs in P. aeruginosa, which, as expected, is lacking in the ppk mutant (Fig.…”

“…CV represents the control vector pMMB66HE and PPK ϩϩϩ the PPK-overproducing plasmid pHEPAK11. coordinated fashion, either en masse at the colony edge or as rafts of migrating cells temporarily leaving the colony behind; and (iii) production of extracellular slime consisting of polysaccharide and͞or biosurfactant (5)(6)(7)(33)(34)(35)(36)(37). Such multiflagellated strains of P. aeruginosa had been observed earlier but their capacity to swarm was not investigated (38).…”

Adhesion of bacteria and diatoms to surfaces in the sea: a review

“…unless the medium is deficient in iron, the wild type organism will not synthesize lateral flagella. The process described above does not appear to unique and has been discovered in certain Serratia (Alberti & Harshey 1990), but at the moment it cannot be considered to be universal in flagellate marine bacteria.…”

Lateral Flagella and Swarming Motility in Aeromonas Species

“…Swarming has been studied extensively in Proteus mirabilis, in which it is characterized by differentiation of short, motile, vegetative cells at the colony margin into elongated, hyperflagellated swarm cells that assemble into multicellular rafts and migrate away from the colony (3,9). Other members of the family Enterobacteriaceae have also been shown to exhibit the swarming phenomenon (1,14,47). For these organisms, hyperflagellation is due to increased expression of their peritrichous flagella, although the number of flagella per unit area of the cell surface is smaller than the number observed on P. mirabilis (twice as many flagella compared to 10 to 50 times more flagella, respectively).…”