title: Taking the fungal highway: mobilization of pollutant-degrading bacteria by fungi.
abstract: The capacity of fungi to serve as vectors for the dispersion of pollutant-degrading bacteria was analyzed in laboratory model systems mimicking water-saturated (agar surfaces) and unsaturated soil environments (glass-bead-filled columns). Two common soil fungi (Fusarium oxysporum and Rhexocercosporidium sp.) forming hydrophilic and hydrophobic mycelia, respectively, and three polycyclic aromatic hydrocarbon degrading bacteria (Achromobacter sp. SK1, Mycobacterium frederiksbergense LB501TG, and Sphingomonas sp. L138) were selected based on the absence of mutual antagonistic effects. It was shown that fungal hyphae act as vectors for bacterial transport with mobilization strongly depending on the specific microorganisms chosen: The motile strain Achromobacter sp. SK1 was most efficiently spread along hyphae of hydrophilic F. oxysporum in both model systems with transport velocities of up to 1 cm d(-1), whereas no dispersion of the two nonmotile strains was observed in the presence of F. oxysporum. By contrast, none of the bacteria was mobilized along the hydrophobic mycelia of Rhexocercosporidium sp. growing on agar surfaces. In column experiments however, strain SK1 was mobilized by Rhexocercosporidium sp. It is hypothesized that bacteria may move by their intrinsic motilitythrough continuous (physiological) liquid films forming around fungal hyphae. The results of this study suggest that the specific stimulation of indigenous fungi may be a strategy to mobilize pollutant-degrading bacteria leading to their homogenization in polluted soil thereby improving bioremediation.
authors.affiliation: Swiss Federal Institute of Technology Lausanne (EPFL), ENAC-ISTE-LPE, CH-1015 Lausanne, Switzerland.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Kohlmeier
authors.forename: Theo H M
authors.initials: TH
authors.lastname: Smits
authors.forename: Roseanne M
authors.initials: RM
authors.lastname: Ford
authors.forename: Christoph
authors.initials: C
authors.lastname: Keel
authors.forename: Hauke
authors.initials: H
authors.lastname: Harms
authors.forename: Lukas Y
authors.initials: LY
authors.lastname: Wick
mesh_terms: D000362:Agar; D001203:Ascomycota / Q000502:physiology*; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001692:Biological Transport / Q000502:physiology; D004787:Environmental Pollution / Q000517:prevention & control*; D025301:Hyphae / Q000502:physiology*; D009068:Movement; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D000362:Agar