A novel extracellular cyclic lipopeptide which promotes flagellum-dependent and -independent spreading growth of Serratia marcescens

Abstract

Serrawettin W2, a surface-active exolipid produced by nonpigmented Serratia marcescens NS 25, was examined for its chemical structure and physiological functions. The chemical structure was determined by degradation analyses, infrared spectroscopy, mass spectrometry, and proton magnetic resonance spectroscopy.Serrawettin W2 was shown to be a novel cyclodepsipeptide containing a fatty acid (3-hydroxydecanoic acid) and five amino acids. The peptide was proposed to be D-leucine (N-bonded to the carboxylate of the fatty acid)-L-serine-L-threonine-D-phenylalanine-L-isoleucine (bonded to the 3-hydroxyl group). By examining the effects of isolated serrawettin W2 on serrawettinless mutants, this lipopeptide was shown to be active in the promotion of flagellum-independent spreading growth of the bacteria on a hard agar surface. The parent strain NS 25 formed a giant colony with a self-similar characteristic after incubation for a relatively long time (1 to 2 weeks), similar to other fractal colony-producing strains of S. marcescens (producers of the different serrawettins Wl and W3). On a semisolid medium that permitted flagellum-dependent spreading growth, an external supply of serrawettin W2 accelerated surface translocation of a serrawettinless mutant during a short period (12 h) of observation. In contrast, bacterial translocation in the subsurface space of the semisolid agar was not enhanced by serrawettins. Thus, the extracellular lipids seem to contribute specifically to the surface translocation of the bacteria by exhibiting surfactant activity.Previously, we reported that Serratia marcescens and Serratia rubidaea demonstrate wetting activity on various hydrophilic and hydrophobic surfaces (1,12,13,17). The extracellular products responsible for such activity were isolated and named serrawettins (lipopeptides produced by S. marcescens) (15, 16) and rubiwettins [,-D-glucopyranosyl 3-(3'-hydroxytetradecanoyloxy)decanoate and its glucosefree relatives produced by S. rubidaea] (13). Serrawettin Wi, produced by many pigmented S. marcescens strains, is a surface-active cyclodepsipeptide identical to serratamolide, which was discovered by Wasserman as an antibiotic (25, 26). Serrawettins W2 and W3 are also surface-active exolipids of nonpigmented strains of S. marcescens (W2 from strain NS 25 and W3 from strains NS 45 and NS 50). Although serrawettins W2 and W3 were identified as novel types of ninhydrin-negative lipopeptides giving protonated molecular ions at 732 and 684 mlz, respectively, in positive secondary ion mass spectra, the precise chemical structures remained unsolved. In contrast to serrawettin Wl, which has a symmetric dilactone structure composed of 2 mol of serine and 2 mol of 3-hydroxydecanoic acids (12, 26), W2 and W3 were shown to have asymmetric cyclic structures composed of several amino acids and fatty acids (14). In the present study, the chemical structure of serrawettin W2 was determined by a combination of conventional degradation analyses and nondegradation analyses such as two-dimensional nuc...

Deadly competition between sibling bacterial colonies

“…To coordinate such cooperative ventures, bacteria have developed methods of cell-to-cell signaling (14)(15)(16)(17)(18)(19), including direct physical interactions by extra membrane polymers (20)(21), secretion of extracellular materials like lubricating surfactin (22)(23), biochemical communication such as quorum sensing and chemotaxis signaling (by using mediators ranging from simple molecules and polymers to peptides and complex proteins) (24)(25)(26)(27)(28)(29), and exchange of genetic information (by plasmids and viruses) (30)(31)(32). Bacterial communication-based cooperation can lead to colony morphogenesis, coordinated gene expression, regulated cell differentiation, and division of tasks.…”

Switching of the rotational direction of rhizoidal colonies in a newly isolated <i>Bacillus mycoides</i> strain Ko01

“…The complete understanding of the underlying principle that allows spreading on solid surfaces with such low water availability requires further study. Surfactants which alter the surface tension of fluids surrounding the colonies were shown to be important in the spreading of some bacteria (Angelini et al, 2009;Matsuyama et al, 1992). The effects of surfactant production on rhizoidal growth pattern and its involvement in chirality switching in Ko01 are currently under investigation.…”

Flagella-independent surface motility in Salmonella enterica serovar Typhimurium

“…2D), which correlates with better bacterial replication at high than low Mg 2+ (26). Sliding motility typically requires surfactants to lower surface friction-for example, serrawettin in Serratia marcescens (28,34), acetylated glycopeptidolipids in Mycobacteria smegmatis (35,36), and surfactin in Bacillus subtilis (37). In S. enterica, however, low Mg 2+ -promoted motility was not affected when the genes responsible for the production of cellulose, capsule, colanic acid, LPS, ECA, or O-antigen were inactivated (Fig.…”

“…Wetting agents often promote motility on cell surfaces by reducing the friction between a cell and its substrate (28,29). We tested the potential role of various wetting agents by investigating the motility of mutants defective in the production of particular surface molecules.…”