Imaging "ecological engineers": a novel quantum dots approach to map microbes in complex soil structures with x-rays
EMSL Project ID
48712
Abstract
Our goal is to understand how microbes engineer their environment into the dynamic three-dimensional complex that promotes microbial diversity, influences the terrestrial carbon cycle, supports soil fertility, and impacts fate and transport of contaminants. We propose to develop a new tool for visualizing microbial metabolic function in soils. A novel application of quantum dots (QDs) will allow us to track specific nutrients as they are utilized by microbes and incorporated into soil pore spaces. Our approach will image the heterogeneous distribution of microbial metabolic processes in situ, which has never been done in opaque media such as soil. First, we must ensure that CdSe quantum dots can be used to track microbial uptake of biologically relevant organic substrates. Kinetics of substrate uptake by cells is exceedingly challenging to measure in environmental samples, especially in complex communities of organisms or when substrates are provided in combination. We aim to measure microbial use of substrates of varying complexity by conjugating quantum dots to the compounds. We have grown bacteria under varying environmental conditions, added QDs conjugated to substrates of varying complexity to the cultures, and then sampled the cultures to observe QD uptake. We have used confocal and fluorescent microscopes as well as X-ray fluorescence microscopy at the Advanced Photon Source to identify cells that have incorporated the QD-labeled substrates. However, we require unequivocal evidence that rather than being associated with the exterior of cell wells, the QDs have been assimilated by the bacteria. This proposal requests access to thin sectioning and TEM capabilities to demonstrate the location of QD associations with cells. Ultimately, we will use this approach in 3 dimensional, opaque samples such as soil by using X-ray fluorescence at the APS to detect dense CdSe core QDs bioaccumulated in cells. By knowing that conjugated QDs are incorporated into cells, we can better interpret X-ray data to understand how microbes interact in their environment.Project Details
Project type
Limited Scope
Start Date
2015-01-12
End Date
2015-03-14
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)