Correlative High-Resolution Imaging and Spectroscopy to Characterize the Structure and Biogeochemical Function of Microbial Biofilms
EMSL Project ID
44631
Abstract
This proposal leverages knowledge and experience gained from DOE-funded research to elucidate the mechanisms involved in dissimilatory metal reduction, as well as, microscale imaging and analytical techniques developed at EMSL to study the functional roles of hydrated biofilm-associated EPS in DOE-relevant biogeochemical processes. Activities under this proposal will support a Chemical Imaging Initiative (CII) Laboratory Directed Research and Development (LDRD) project (26INCI10101) focused on nanoscale structural and chemical imaging of microbial biofilms. Direct examination of natural and engineered environments has revealed that the majority of microorganisms in these systems live in structured communities termed biofilms. In addition to microbial cells, biofilms are comprised of a poorly characterized organic matrix commonly referred to as extracellular polymeric substance (EPS) that may play roles in facilitating microbial interactions and biogeochemical reactions including extracellular electron transfer. Using high-resolution electron microscopy (EM) imaging at EMSL, a highly-hydrated 3-dimensionmal (3d) bacterial EPS has been shown to be produced during microbial metal reduction. The juxtaposition of extracellular electron transfer proteins and nanoparticulate reduced metal suggested that EPS played a key role in metal capture and precipitation and, possibly, extracellular electron transfer. Therefore, understanding how biofilm EPS functions and interacts with inorganic substrates such as metal ions and mineral surfaces connects the molecular-scale biogeochemical processes to those at the microorganism-level and provides insight to how microorganisms influence larger, pore-scale biogeochemical reactions. The objectives of this research are to develop fundamental capabilities for enhanced visualization, compositional analysis, and functional characterization of biofilm EPS and better understand EPS influences on biogeochemical reactions. Using a multi-faceted approach of imaging and analytical techniques to elicit the complex microbial and biogeochemical interactions, biofilm communities will be surveyed using multi-scale imaging and spectroscopies to characterize the biofilm EPS in its nearest-to-native state. In this project, we will correlate EMSL resources (conventional and cryogenic EM capabilities and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) imaging) with synchrotron-based X-ray fluorescence micro-imaging, single absorption grating phase contrast, double grating phase contrast, with tomography, and scanning transmission X-ray microscopy to produce high-sensitivity, element-specific distributions which correspond to EM images and 3d reconstructions of the biofilm at the nanometer scale. Together, these techniques will enable us to construct a high resolution, cutting-edge 'chemical image' of biofilms as they influence biogeochemical processes including those central to DOE missions in subsurface contaminant fate and transport and carbon cycling and sequestration.
Project Details
Project type
Exploratory Research
Start Date
2011-07-29
End Date
2012-07-29
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Hua X, MJ Marshall, Y Xiong, X Ma, Y Zhou, AE Tucker, Z Zhu, S Liu, and XY Yu. 2015. "Two-dimensional and three-dimensional dynamic imaging of live biofilms in a microchannel by time-of-flight secondary ion mass spectrometry." Biomicrofluidics 9(3):Article No. 031101. doi:10.1063/1.4919807