Phylogenetic Composition of Bacterioplankton Cultivated from Soyang Lake Using Dilution-to-extinction Approach

초록

High throughput cultivation based on dilution-to-extinction showed a great potential to isolate uncultured 이 i gotrophic marine bacteria. ln this study we report the application of dilution-to-extinction culturing to freshwater bacterioplankton. Similar to marine systems, many important freshwater bacterial clades have been reported to be uncultured yet, including LD12 of the Alphaproleobacteria, LD28 of the Betaproteobacteria, and acI of the Actinobacleria. A water sample of Soyang Lake was examined using dilution-to-extinction culturing with very low nutrient-amended lake water as culture media. Most of the 313 strains cultivated from 720 inoculated wells belonged to the Belaproteobacleria andAlphaproteobacteria，with a very small number of Actinobacteria and Gammaproteobacteria. Only 73 strains formed colonies on 1/3R2A and/or 1/ 10R2A agar plates. lnterestingly, we successfully isolated several major freshwatεr bacterial groups, particularly acI of the AClinobacteria; Limnohabitans and Polynucleobacter of the Betaproteobacteria, which suggests the potential of dilution-to-extinction culturing in cultivating representatives of previously uncultured freshwater bacterial groups.