A molecular approach to identify active microbes in environmental eukaryote clone libraries.

Area of Science:

• Marine microbiology
• Molecular ecology

Background:

• Distinguishing active from inactive microbial communities is crucial for understanding ecosystem function.
• Anoxic marine environments present unique challenges for microbial community analysis.

Purpose of the Study:

• To develop a rapid, simultaneous RNA and DNA extraction method for eukaryote plankton.
• To differentiate between active and inactive microbial populations in anoxic fjord samples.
• To characterize the microeukaryote community structure and identify key functional groups.

Main Methods:

• Simultaneous extraction of RNA and DNA from plankton samples.
• Construction of rRNA- and rDNA-derived clone libraries.
• Analysis of protistan phylotypes using sequencing and comparative library analysis.
• Application of reverse transcription-polymerase chain reaction (RT-PCR) and PCR.

Main Results:

• The developed protocol yields high-purity RNA and DNA suitable for molecular analysis.
• Analysis revealed 84 distinct protistan phylotypes, with 27% found in both rRNA and rDNA libraries.
• The microeukaryote community was dominated by anaerobic ciliates and heterotrophic stramenopile flagellates.
• Phototrophic dinoflagellates and parasites were identified as nonindigenous using the rDNA library.

Conclusions:

• The simultaneous RNA/DNA extraction method is effective for assessing active microbial communities in challenging environments.
• The study highlights the significant role of bacterivore organisms in anoxic marine food webs.
• Comparative library analysis is valuable for identifying nonindigenous or dormant species within microbial assemblages.