10] Directed movement and surface-borne motility of myxococcus and pseudomonas

Abstract

Publisher Summary This chapter discusses Biofilms having elaborate internal architectures composed of pillars of biomass surrounded by regular vertical and horizontal channels. These channels carry currents that deliver essential nutrients and oxygen for bacterial growth. Myxococcus xanthus is a soil bacterium that associates in biofilms and glides over solid surfaces by an unknown mechanism. When M. xanthus is starved for nutrients, complex motility patterns are initiated to convert a fiat two-dimensional swarm to a spherical fruiting body. At least six intercellular signals and gliding motility are essential to complete morphogenesis. While the M. xanthus fruiting body is a dramatic and highly specialized type of biofilm, similar regulatory systems appear to control biofilms in other organisms. Chemotaxis, directed movement up chemical gradients, may play a role in both P. aeruginosa and M. xanthus surface translocation. Type IV pili have been implicated as the P. aeruginosa twitching motor and some pilus-deficient strains have mutations in genes similar to those of Escherichia coli che genes, which encode proteins that transmit information about chemoattractants. Hydrophobic surfactants provide an ideal venue for regulating surface motility in submerged biofilms, and it seems plausible that chemotaxis could be an important factor in the organization of biofilm tertiary structure; Gliding and twitching motility are similar in that both require a solid surface and type IV pili. This chapter describes techniques used to isolate the M. xanthus gliding chemoattractant and apply them to identify a P. aeruginosa twitching chemoeffector.