Light element analysis of individual bacteria by x-ray microanalysis.

Area of Science:

• Microbiology
• Analytical Chemistry
• Biogeochemistry

Background:

• Bulk elemental analysis methods often obscure single-cell variability.
• Fractionation techniques used in bulk analysis can introduce artifacts.
• Understanding elemental composition at the single-cell level is crucial for microbial ecology.

Purpose of the Study:

• To develop and validate a method for single-cell elemental analysis using X-ray microanalysis (XRMA).
• To compare XRMA single-cell data with traditional bulk analysis methods.
• To demonstrate the utility of XRMA for classifying microbial cells and particles.

Main Methods:

• Utilized transmission electron microscopy coupled with X-ray microanalysis (XRMA).
• Calibrated measurements using latex beads and defined compound microdrops.
• Analyzed elemental composition (excluding hydrogen) in single microbial cells and particles.

Main Results:

• XRMA accurately measured major elements in single microbial cells (e.g., Escherichia coli, Emiliana huxleyi).
• Nitrogen/Carbon ratios from XRMA differed from bulk CHN analysis for E. coli.
• Elemental weight fractions for CaCO3 in coccoliths aligned with theoretical values.

Conclusions:

• XRMA provides a powerful tool for single-cell elemental analysis, overcoming limitations of bulk methods.
• This method enables precise classification of particles (e.g., biotic vs. abiotic).
• Single-cell elemental analysis can reveal nutritional status, macromolecular composition, and community structure.