Raman chemical imaging of the rhizosphere bacterium Pantoea sp. YR343 and its co-culture with Arabidopsis thaliana

Journal Article · Mon Feb 29 00:00:00 EST 2016 · Analyst

DOI:https://doi.org/10.1039/C6AN00080K· OSTI ID:1371709

Polisetti, Sneha ^[1]; Bible, Amber N. ^[2]; Morrell-Falvey, Jennifer L. ^[2]; Bohn, Paul W. ^[3]

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1. Univ. of Notre Dame, IN (United States). Dept. of Chemical and Biomolecular Engineering
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Univ. of Notre Dame, IN (United States). Dept. of Chemical and Biomolecular Engineering; Univ. of Notre Dame, IN (United States). Dept. of Chemistry and Biochemistry

Chemical imaging of plant-bacteria co-cultures renders it possible to characterize bacterial populations and behaviors and their interactions with proximal organisms, under conditions closest to the environment in the rhizosphere. Here Raman micro-spectroscopy and confocal Raman imaging are used as minimally invasive probes to study the rhizosphere bacterial isolate, Pantoea sp. YR343, and its co-culture with model plant Arabidopsis thaliana by combining enhanced Raman spectroscopies with electron microscopy and principal component analysis (PCA). In this work, the presence of carotenoid pigments in the wild type Pantoea sp. YR343 was characterized using resonance Raman scattering, which was also used to confirm successful disruption of the crtB gene in an engineered carotenoid mutant strain. Other components of the Pantoea sp. YR343 cells were imaged in the presence of resonantly enhanced pigments using a combination of surface enhanced Raman imaging and PCA. Pantoea sp. YR343 cells decorated with Ag colloid synthesized ex situ gave spectra dominated by carotenoid scattering, whereas colloids synthesized in situ produced spectral signatures characteristic of flavins in the cell membrane. Scanning electron microscopy (SEM) of whole cells and transmission electron microscopy (TEM) images of thinly sliced cross-sections were used to assess structural integrity of the coated cells and to establish the origin of spectral signatures based on the position of Ag nanoparticles in the cells. Finally, raman imaging was also used to characterize senescent green Arabidopsis thaliana plant roots inoculated with Pantoea sp. YR343, and PCA was used to distinguish spectral contributions from plant and bacterial cells, thereby establishing the potential of Raman imaging to visualize the distribution of rhizobacteria on plant roots.

• Research Organization: University of Notre Dame, IN (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-00OR22725; ORNL-4000132808
• OSTI ID: 1371709
• Alternate ID(s): OSTI ID: 1261315
• Journal Information: Analyst, Vol. 141, Issue 7; ISSN 0003-2654
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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