Motility in liquid and semisolid media of Paenibacillus polymyxa associative rhizobacteria differing in exopolysaccharide yield and properties

• Published in: Symbiosis (Philadelphia, Pa.) Pa.), 2018, Vol.74 (1), p.31-42
• Main Authors: Yegorenkova, Irina V., Tregubova, Kristina V., Schelud’ko, Andrei V.
• Format: Article
• Language: English
• Subjects: Agar; Bacteria; Biomedical and Life Sciences; Carbon sources; Colonies; Developmental Biology; Dyes; Ecology; Environmental conditions; Evolutionary Biology; Exopolysaccharides; Flagella; Life Sciences; Microbiology; Migration; Motility; Paenibacillus polymyxa; Physicochemical properties; Plant Sciences; Polymers; Strains (organisms); Sucrose; Swarming
• ISSN: 0334-5114; 1878-7665
• DOI: 10.1007/s13199-017-0492-5

Paenibacillus polymyxa rhizobacteria associate with a wide range of plants and promote plant growth and development. These bacteria produce exopolysaccharides, which are very important for P. polymyxa adaptation to changing environmental conditions. In this study, five P. polymyxa strains differing in exopolysaccharide yield and properties (CCM 1465, CCM 1460, CCM 1459 T , 88A, and 92) were investigated for motility in a liquid and a semisolid nutrient medium with either glucose or sucrose as the carbon source. In the liquid medium, all strains except CCM 1460 were motile and swam by peritrichous flagella. After being stab inoculated into the semisolid (0.4% agar) medium, all strains except CCM 1460 switched to collective swarming and formed concentric macrocolonies with different diameters, depending on the strain and the carbon source used. On the semisolid medium containing the vital dye Congo red, P. polymyxa adsorbed the dye, forming stained colonies. No changes in colony morphology were observed. At 37.5 μg ml −1 of Congo red, swarming was strongly suppressed: the swarming ring diameters of strains 92, CCM 1459 T , 88A, and CCM 1465 ranged from 12.4 to 17% (glucose) and from 9.5 to 16.0% (sucrose) of the colony diameters obtained from bacterial growth without the dye. The results suggest that the speed of collective migration of P. polymyxa on agarized media may be affected, among other factors, by the yield and physicochemical properties of the bacterial exopolysaccharides. Further, the results suggest that Congo red influences the collective migration speed of P. polymyxa by forming a complex with the bacteria’s carbohydrate polymers – an event that alters bacterial surface structure and affects intercellular interactions.