Mutations that impair swarming motility in Serratia marcescens 274 include but are not limited to those affecting chemotaxis or flagellar function

Abstract

Serratia marcescens exists in two cell forms and displays two kinds of motility depending on the type of growth surface encountered (L. Alberti and R. M. Harshey, J. Bacteriol. 172:4322-4328, 1990). In liquid medium, the bacteria are short rods with few flagella and show classical swimming behavior. Upon growth on a solid surface (0.7 to 0.85% agar), they differentiate into elongated, multinucleate, copiously flagellated forms that swarm over the agar surface. The flagella of swimmer and swarmer cells are composed of the same flagellin protein. We show in this study that disruption of hag, the gene encoding flagellin, abolishes both swimming and swarming motility. We have used transposon mini-Mu lac kan to isolate mutants of S. marcescens defective in both kinds of motility. Of the 155 mutants obtained, all Fla- mutants (lacking flagella) and Mot- mutants (paralyzed flagella) were defective for both swimming and swarming, as expected. All Che- mutants (chemotaxis defective) were also defective for swarming, suggesting that an intact chemotaxis system is essential for swarming. About one-third of the mutants were specifically affected only in swarming. Of this class, a large majority showed active "swarming motility" when viewed through the microscope (analogous to the active "swimming motility" of Che- mutants) but failed to show significant movement away from the site of initial inoculation on a macroscopic scale. These results suggest that bacteria swarming on a solid surface require many genes in addition to those required for chemotaxis and flagellar function, which extend the swarming movement outward. We also show in this study that nonflagellate S. marcescens is capable of spreading rapidly on low-agar media.

FlhF, a signal recognition particle-like GTPase, is involved in the regulation of flagellar arrangement, motility behaviour and protein secretion in Bacillus cereus

“…6). This finding is in agreement with a robust literature demonstrating that deletions in flagellar genes severely impair or abolish the ability to undergo swarming differentiation in swarming-proficient species (Gygi et al, 1995;Harshey & Matsuyama, 1994;O'Rear et al, 1992;Senesi et al, 2002;Young et al, 1999b). In addition, flhF has been recently demonstrated to be required for swarming motility in the Gram-negative species P. aeruginosa (Murray & Kazmierczak, 2006).…”

Swarming motility in Bacillus cereus and characterization of a fliY mutant impaired in swarm cell differentiation The EMBL accession number for the sequence reported in this paper is Y08031.

“…Characterization of swarming-defective mutants demonstrated that molecular components of both the chemotaxis system and flagellar apparatus are essential for swarming differentiation in all the Gram-negative bacteria studied so far (Belas et al, 1991(Belas et al, , 1995Burkart et al, 1998 ;Givaudan & Lanois, 2000 ;Gygi et al, 1995 ;O'Rear et al, 1992 ;Young et al, 1999). However, while the role of chemotaxis proteins in swarm-cell differentiation has not been clarified completely, the inability to swarm or to swarm properly exhibited by mutants defective in flagellar proteins (Belas et al, 1991(Belas et al, , 1995O'Rear et al, 1992 ;Young et al, 1999), in motor-switch proteins (Belas et al, 1995 ;Burkart et al, 1998) or in proteins involved in the assembly of flagellar filaments (Gygi et al, 1995 ;Young et al, 1999), is consistent with the essential role played by a functional flagellum-mediated motility for the differentiation of hyperflagellated swarm cells. Almost nothing is known about the molecular components needed for swarming differentiation in Grampositive bacteria, although this striking behaviour has been long recognized in some species of Clostridium and Bacillus (Henrichsen, 1972 ;Hoeniger & Taushel, 1974).…”

“…Moreover, the finding that some bacteria, such as uropathogenic strains of P. mirabilis, produce higher levels of specific virulence factors during their swarmcell state (Allison et al, 1992b(Allison et al, , 1994, is of intrinsic interest as well as of great medical relevance. Swarming differentiation has been studied mostly in Gram-negative rods and much has been learned about the regulatory mechanisms of swarming in Serratia liquefaciens, Serratia marcescens, Salmonella typhimurium, Xenorhabdus nematophilus, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Yersinia enterocolitica and Escherichia coli, as well as in P. mirabilis (Belas et al, 1991 ;Eberl et al, 1996 ;Givaudan & Lanois, 2000 ;Harshey & Matsuyama, 1994 ;O'Rear et al, 1992 ;Rashid & Kornberg, 2000 ;Stewart et al, 1997 ;Young et al, 1999). Characterization of swarming-defective mutants demonstrated that molecular components of both the chemotaxis system and flagellar apparatus are essential for swarming differentiation in all the Gram-negative bacteria studied so far (Belas et al, 1991(Belas et al, , 1995Burkart et al, 1998 ;Givaudan & Lanois, 2000 ;Gygi et al, 1995 ;O'Rear et al, 1992 ;Young et al, 1999).…”

“…Swarming differentiation has been studied mostly in Gram-negative rods and much has been learned about the regulatory mechanisms of swarming in Serratia liquefaciens, Serratia marcescens, Salmonella typhimurium, Xenorhabdus nematophilus, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Yersinia enterocolitica and Escherichia coli, as well as in P. mirabilis (Belas et al, 1991 ;Eberl et al, 1996 ;Givaudan & Lanois, 2000 ;Harshey & Matsuyama, 1994 ;O'Rear et al, 1992 ;Rashid & Kornberg, 2000 ;Stewart et al, 1997 ;Young et al, 1999). Characterization of swarming-defective mutants demonstrated that molecular components of both the chemotaxis system and flagellar apparatus are essential for swarming differentiation in all the Gram-negative bacteria studied so far (Belas et al, 1991(Belas et al, , 1995Burkart et al, 1998 ;Givaudan & Lanois, 2000 ;Gygi et al, 1995 ;O'Rear et al, 1992 ;Young et al, 1999). However, while the role of chemotaxis proteins in swarm-cell differentiation has not been clarified completely, the inability to swarm or to swarm properly exhibited by mutants defective in flagellar proteins (Belas et al, 1991(Belas et al, , 1995O'Rear et al, 1992 ;Young et al, 1999), in motor-switch proteins (Belas et al, 1995 ;Burkart et al, 1998) or in proteins involved in the assembly of flagellar filaments (Gygi et al, 1995 ;Young et al, 1999), is consistent with the essential role played by a functional flagellum-mediated motility for the differentiation of hyperflagellated swarm cells.…”

Identification and Characterization of the pswP Gene Required for the Parallel Production of Prodigiosin and Serrawettin W1 in Serratia marcescens

“…Genetic analysis of parallelism in production of these exolipids indicated an essential step in PCP-dependent systems that is common to biosynthesis of prodigiosin and serrawettin W1 by S. marcescens. (6) was used routinely in the genetic experiments as described previously (16). The bacteria grown on a peptone-glycerol (PG) agar medium (15) were examined for pigment production and wetting activity (spontaneous spreading of bacterial suspension on a glass slide) as described previously (7).…”