PARENT SESSION
Oral Session #22: Mycorrhizae and ecosystem function.
Presiding: A. Tuininga
Monday, August 5. 1:00 PM to 3:45 PM. Grand Ballroom East, Radisson.
Encapsulated biosensors detect sugar in the rhizosphere.
Herron, Patrick*,1, Bringhurst, Ryan2, Gage, Daniel2, Cardon, Zoe1, 1 Department of Ecology and Evolutionary Biology, Storrs, Connecticut2 Department of Molecular and Cell Biology, Storrs, Connecticut
ABSTRACT- The ability to track labile carbon availability around roots contributes to an understanding of how plants interact with soil microorganisms, potentially influencing nutrient availability in the rhizosphere. We have developed microbial biosensors (Sinorhizobium meliloti) that express green fluorescence protein (GFP) when galactosides are in their environment. Though these biosensors have been used sucessfully to explore galactoside concentrations around roots in nonsterile soils (Bringhurst et al. 2001), predation by soil protozoa decreases biosensor population sizes and makes biosensor distribution in soil less uniform. By encapsulating biosensors in very small Sodium alginate/Polyethylene glycol beads, protozoal predation is deterred, and biosensors are anchored more strongly in the soil matrix. The biosensors still express green fluorescence upon metabolizing galactoside sugars in their environment, and this fluorescence is visible through the encapsulation gel using epifluorescence microscopy. This technique allows non-destructive, spatially explicit measurements of sugar distribution in the rhizosphere to be performed in non-sterile soils even when protozoal grazer populations are active.
KEY WORDS: biosensor, rhizosphere, carbon, encapsulation