Mobilization of Pollutant-Degrading Bacteria by Eukaryotic Zoospores.
The controlled mobilization of pollutant-degrading bacteria has been identified as a promising strategy for improving bioremediation performance. We tested the hypothesis whether the mobilization of bacterial degraders may be achieved by the action of eukaryotic zoospores. We evaluated zoospores that are produced by the soil oomycete Pythium aphanidermatum as a biological vector, and, respectively, the polycyclic aromatic hydrocarbon (PAH)-degrading bacteria Mycobacterium gilvum VM552 and Pseudomonas putida G7, acting as representative nonflagellated and flagellated species. The mobilization assay was performed with a chemical-in-capillary method, in which zoospores mobilized bacterial cells only when they were exposed to a zoospore homing inducer (5% (v/v) ethanol), which caused the tactic response and settlement of zoospores. The mobilization was strongly linked to a lack of bacterial motility, because the nonflagellated cells from strain M. gilvum VM552 and slightly motile, stationary-phase cells from P. putida G7 were mobilized effectively, but the actively motile, exponentially grown cells of P. putida G7 were not mobilized. The computer-assisted analysis of cell motility in mixed suspensions showed that the swimming rate was enhanced by zoospores in stationary, but not in exponentially grown, cells of P. putida G7. It is hypothesized that the directional swimming of zoospores caused bacterial mobilization through the thrust force of their flagellar propulsion. Our results suggest that, by mobilizing pollutant-degrading bacteria, zoospores can act as ecological amplifiers for fungal and oomycete mycelial networks in soils, extending their potential in bioremediation scenarios.
Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Apartado 1052, Seville 41080, Spain.
Rungroch
R
Sungthong
Aberdeen Oomycete Laboratory, University of Aberdeen, Institute of Medical Sciences , Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
Pieter
P
van West
Uppsala BioCenter, Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences , Uppsala 750 07, Sweden.
Fredrik
F
Heyman
Uppsala BioCenter, Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences , Uppsala 750 07, Sweden.
Dan Funck
DF
Jensen
Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Apartado 1052, Seville 41080, Spain.
Jose Julio
JJ
Ortega-Calvo
D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D056890:Eukaryota / Q000378:metabolism*; D011084:Polycyclic Aromatic Hydrocarbons; D012988:Soil Microbiology; D012989:Soil Pollutants
D011084:Polycyclic Aromatic Hydrocarbons; D012989:Soil Pollutants