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Isolation of functional single cells from environments using a micromanipulator: application to study denitrifying
Naoaki Ashida1, Satoshi Ishii, Sadakazu Hayano
1Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
Applied Microbiology and Biotechnology
|November 26, 2009
Summary
We developed a novel functional single-cell (FSC) isolation method to identify active microbes in environmental samples. This method successfully isolated denitrifying bacteria from rice paddy soil, revealing key genera involved in the process.
Area of Science:
- Microbiology
- Environmental Science
- Molecular Biology
Background:
- Studying microbial communities in environmental samples is crucial for understanding ecological processes.
- Isolating functionally active single cells is challenging but essential for detailed analysis.
- Current methods may not accurately capture the functional capacity of microbial populations.
Purpose of the Study:
- To develop and validate a novel method for isolating functionally active single cells from environmental samples.
- To apply this method to characterize a denitrifying microbial community in rice paddy soil.
- To assess the efficacy of the new method compared to traditional techniques.
Main Methods:
- The functional single-cell (FSC) isolation method combines substrate-responsive direct viable counts, live-cell staining (5-carboxyfluorescein diacetate acetoxymethyl ester), and micromanipulation.
- Isolated cells were cultivated in a suitable medium for further analysis.
- The method was evaluated by comparing results with conventional most probable number analysis on rice paddy soil samples.
Main Results:
- The FSC isolation method yielded denitrifier counts comparable to the most probable number analysis.
- 37 denitrifying bacteria were successfully isolated using the FSC method.
- Analysis revealed the presence of the copper-containing nitrite reductase gene (nirK) in some isolates.
- 16S rRNA gene sequencing identified Azospirillum and Ochrobactrum as potentially dominant denitrifier genera in the studied soil.
Conclusions:
- The developed functional single-cell (FSC) isolation method is effective for obtaining viable, single microbial cells from complex environmental matrices.
- This method provides a valuable tool for microbial ecology research, enabling the isolation and characterization of specific functional groups.
- The study identified key denitrifying bacteria in rice paddy soil, contributing to our understanding of nitrogen cycling in these ecosystems.
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