Flow cytometric fingerprinting for microbial strain discrimination and physiological characterization

Area of Science:

• Microbiology
• Biotechnology
• Analytical Chemistry

Background:

• Microbial population analysis is crucial for understanding microbial communities and biotechnological applications.
• DNA sequencing is a common tool for microbial identification, but flow cytometry offers a new approach.
• Flow cytometric fingerprinting is an emerging technique for analyzing bacterial populations.

Purpose of the Study:

• To apply flow cytometric fingerprinting for discriminating between Lactobacillus strains.
• To evaluate the effectiveness of different fluorescent stains (SYBR green I, propidium iodide) for discrimination.
• To assess the method's ability to detect physiological changes and its sensitivity.

Main Methods:

• Flow cytometric fingerprinting was employed to analyze 29 Lactobacillus strains.
• Strains were stained with SYBR green I alone and in combination with propidium iodide.
• The method's sensitivity was tested using polystyrene beads and bacterial mixtures, and its ability to differentiate growth phases was demonstrated.

Main Results:

• Flow cytometry successfully discriminated among 27 of the 29 Lactobacillus strains.
• Combined SYBR green I and propidium iodide staining enhanced discriminatory power.
• The technique could detect changes in relative abundance as low as 1.2% in bead mixtures and 1.2-5% in bacterial mixtures.
• Different growth phases of microbial cultures were distinguishable.

Conclusions:

• Flow cytometric fingerprinting is a sensitive and reproducible technique for bacterial analysis.
• It shows potential for the dereplication of bacterial isolates.
• The method can be used to monitor physiological states and community composition shifts.