Rapid quantification of rice root-associated bacteria by flow cytometry.

Area of Science:

• Microbiology
• Plant Science
• Agronomy

Background:

• Understanding plant-bacterium interactions is crucial for agricultural advancements.
• Epiphytic bacteria colonize plant roots, influencing plant health and growth.
• Accurate enumeration of these bacteria is essential for research.

Purpose of the Study:

• To develop and validate a flow cytometry-based method for enumerating epiphytic bacteria on plant roots.
• To compare the efficacy of flow cytometry with the traditional plate count method.
• To assess the accuracy and efficiency of bacterial enumeration techniques.

Main Methods:

• Development of a flow cytometry protocol for bacterial enumeration.
• Application of flow cytometry to rice plants (Oryza sativa) colonized with Herbaspirillum rubrisubalbicans and Azospirillum brasilense.
• Comparison of flow cytometry results with the traditional plate count method.

Main Results:

• Flow cytometry provided similar counts for H. rubrisubalbicans as the plate count method (approx. 10^9 CFU g(-1)).
• Flow cytometry yielded approximately 10-fold higher counts of viable A. brasilense on rice roots compared to the plate count method.
• The plate count method may underestimate epiphytic bacterial populations.

Conclusions:

• Flow cytometry is a more precise and faster tool for enumerating epiphytic bacteria than the plate count method.
• This flow cytometry assay overcomes limitations of plate counts, such as long incubation times and reliance on culturable cells.
• The developed method enhances the study of plant-bacterium interactions by providing accurate bacterial quantification.