biosurfactant viscosin produced by Pseudomonas fluorescens SBW25 aids spreading motility and plant growth promotion

• Published in: Environmental microbiology Vol. 16; no. 7; pp. 2267 - 2281
• Main Authors: Alsohim, Abdullah S, Taylor, Tiffany B, Barrett, Glyn A, Gallie, Jenna, Zhang, Xue‐Xian, Altamirano‐Junqueira, Astrid E, Johnson, Louise J, Rainey, Paul B, Jackson, Robert W
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Science 01-07-2014; Blackwell Publishing Ltd; Blackwell
• Subjects: agrochemicals; Animal, plant and microbial ecology; Antibiosis; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Beta vulgaris - growth & development; Beta vulgaris - microbiology; Biological and medical sciences; biosurfactants; DNA Transposable Elements; Flagella - genetics; Flagella - metabolism; flagellum; food security; Fundamental and applied biological sciences. Psychology; Gene Expression; General aspects; genetic techniques and protocols; growth promotion; Microbial ecology; Microbiology; Miscellaneous; Movement; mutagenesis; mutants; Peptides, Cyclic - biosynthesis; Peptides, Cyclic - secretion; pests; phenotype; plant development; plant growth; Plant Growth Regulators - biosynthesis; Plant Growth Regulators - secretion; plant growth-promoting rhizobacteria; plant pathogens; Plant Roots - growth & development; Plant Roots - microbiology; Pseudomonas fluorescens; Pseudomonas fluorescens - genetics; Pseudomonas fluorescens - metabolism; Pythium; Pythium - drug effects; Pythium - growth & development; Pythium - pathogenicity; rhizosphere bacteria; seedlings; Seedlings - growth & development; Seedlings - microbiology; soil; Symbiosis; Trans-Activators - deficiency; Trans-Activators - genetics; transposons; Infection; Pseudomonadales; Biosurfactant; Motility; Growth; Viral disease; Bacteria; Pseudomonadaceae; AIDS; Pseudomonas fluorescens
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.12469

Food security depends on enhancing production and reducing loss to pests and pathogens. A promising alternative to agrochemicals is the use of plant growth‐promoting rhizobacteria (PGPR), which are commonly associated with many, if not all, plant species. However, exploiting the benefits of PGPRs requires knowledge of bacterial function and an in‐depth understanding of plant‐bacteria associations. Motility is important for colonization efficiency and microbial fitness in the plant environment, but the mechanisms employed by bacteria on and around plants are not well understood. We describe and investigate an atypical mode of motility in Pseudomonas fluorescens SBW25 that was revealed only after flagellum production was eliminated by deletion of the master regulator fleQ. Our results suggest that this ‘spidery spreading’ is a type of surface motility. Transposon mutagenesis of SBW25ΔfleQ (SBW25Q) produced mutants, defective in viscosin production, and surface spreading was also abolished. Genetic analysis indicated growth‐dependency, production of viscosin, and several potential regulatory and secretory systems involved in the spidery spreading phenotype. Moreover, viscosin both increases efficiency of surface spreading over the plant root and protects germinating seedlings in soil infected with the plant pathogen Pythium. Thus, viscosin could be a useful target for biotechnological development of plant growth promotion agents.