Use of a lux-marked rhizobacterium as a biosensor to assess changes in rhizosphere C flow due to pollutant stress.
The flow of carbon from plant roots into soil supports a range of microbial processes and is therefore critical to ecosystem function and health. Pollution-induced stress, which influences rhizosphere C flow is of considerable potential importance, and therefore needs to be evaluated. This paper reports on a method, based on reporter gene technology, for quantifying pollutant effects on rhizosphere C flow. The method uses the lux-marked rhizobacterium Pseudomonas fluorescens, where bioluminescence output of this biosensor is directly correlated with the metabolic activity and reports on C flow in root exudate. Plantago lanceolata was treated with paraquat (representing a model pollutant stress) in a simple microcosm system. The lux-biosensor response correlated closely with C concentrations in the exudate and demonstrated that the pollutant stress increased the C flow from the plantago roots, 24 h after application of the herbicide. The lux-reporter system therefore potentially offers a technique for use in assessing the impact of pollutant stress on rhizosphere C flow through the soil microbial biomass.
Porteous
F
F
John Tabor Laboratories, Department of Biological Sciences, University of Essex, Colchester, UK. fport@essex.ac.uk
Killham
K
K
Meharg
A
A
D002244:Carbon / Q000378:metabolism*; D006540:Herbicides / Q000494:pharmacology*; D008163:Luminescent Measurements; D010269:Paraquat / Q000494:pharmacology; D018517:Plant Roots / Q000378:metabolism*; D010943:Plantago / Q000187:drug effects / Q000378:metabolism; D010946:Plants, Medicinal; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000378:metabolism; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000494:pharmacology*
D006540:Herbicides; D012989:Soil Pollutants; D002244:Carbon; D010269:Paraquat