often constitute a large fraction of the bacterioplankton in freshwater systems. Cultivation-independent methods have revealed that the so-called acI lineage frequently represents the most numerous taxon among assemblages of freshwater and even among total freshwater bacterioplankton. Bacteria affiliated with this uncultivated lineage have been detected in freshwater habitats located in various continents and climatic zones but have never been found among terrestrial or offshore marine systems. So far, this ecologically important lineage of freshwater is not represented by a recognized taxon. In this study, we established a stable mixed culture containing a strain affiliated with the acI lineage from a freshwater lake in Austria. The proportion of the strain in the culture could be increased by manipulation of the medium composition by more than one order of magnitude, however all subsequent attempts to isolate this strain into pure culture were unsuccessful. Some of the phenotypic traits of this acI strain were determined and its taxonomic position within the was analysed. Phylogenetic analysis of this organism's 16S rRNA gene revealed a distant relationship with cultivated organisms and recognized species (89 % gene sequence similarity with the latter). Furthermore, this analysis did not support a clear assignment of the strain to any of the recognized families within the phylum . It is suggested that a candidate taxon, ‘ Planktophila limnetica’ is established to represent this strain.


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  1. Allgaier, M. & Grossart, H.-P.(2006). Diversity and seasonal dynamics of Actinobacteria populations in four lakes in northeastern Germany. Appl Environ Microbiol 72, 3489–3497.[CrossRef] [Google Scholar]
  2. Busti, E., Cavaletti, L., Monciardini, P., Schumann, P., Rohde, M., Sosio, M. & Donadio, S.(2006).Catenulispora acidiphila gen. nov., sp. nov., a novel, mycelium-forming actinomycete, and proposal of Catenulisporaceae fam. nov. Int J Syst Evol Microbiol 56, 1741–1746.[CrossRef] [Google Scholar]
  3. Cavaletti, L., Monciardini, P., Schumann, P., Rohde, M., Bamonte, R., Busti, E., Sosio, M. & Donadio, S.(2006).Actinospica robiniae gen. nov., sp. nov. and Actinospica acidiphila sp. nov.: proposal for Actinospicaceae fam. nov. and Catenulisporinae subord. nov. in the order Actinomycetales. Int J Syst Evol Microbiol 56, 1747–1753.[CrossRef] [Google Scholar]
  4. Glöckner, F. O., Zaichikov, E., Belkova, N., Denissova, L., Pernthaler, J., Pernthaler, A. & Amann, R.(2000). Comparative 16S rRNA analysis of lake bacterioplankton reveals globally distributed phylogenetic clusters including an abundant group of Actinobacteria. Appl Environ Microbiol 66, 5053–5065.[CrossRef] [Google Scholar]
  5. Hahn, M. W.(2009). Description of seven candidate species affiliated with the phylum Actinobacteria, representing planktonic freshwater bacteria. Int J Syst Evol Microbiol 59, 112–117.[CrossRef] [Google Scholar]
  6. Hahn, M. W., Lünsdorf, H., Wu, Q. L., Schauer, M., Höfle, M. G., Boenigk, J. & Stadler, P.(2003). Isolation of novel ultramicrobacteria classified as Actinobacteria from five freshwater habitats in Europe and Asia. Appl Environ Microbiol 69, 1442–1451.[CrossRef] [Google Scholar]
  7. Hahn, M. W., Stadler, P., Wu, Q. L. & Pöckl, M.(2004). The filtration-acclimatization-method for isolation of an important fraction of the not readily cultivable bacteria. J Microbiol Methods 57, 379–390.[CrossRef] [Google Scholar]
  8. Lindström, E. S., Kamst-Van Agertveld, M. P. & Zwart, G.(2005). Distribution of typical freshwater bacterial groups is associated with pH, temperature and lake water retention time. Appl Environ Microbiol 71, 8201–8206.[CrossRef] [Google Scholar]
  9. Ludwig, W., Strunk, O., Westram, R., Richter, L., Meier, H., Yadhukumar, Buchner, A., Lai, T., Steppi, S. & other authors(2004).arb: a software environment for sequence data. Nucleic Acids Res 32, 1363–1371.[CrossRef] [Google Scholar]
  10. Murray, R. G. E. & Stackebrandt, E.(1995). Taxonomic note: implementation of the provisional status Candidatus for incompletely described procaryotes. Int J Syst Bacteriol 45, 186–187.[CrossRef] [Google Scholar]
  11. Newton, R. J., Jones, S. E., Helmus, M. R. & McMahon, K. D.(2007). Phylogenetic ecology of the freshwater Actinobacteria acI lineage. Appl Environ Microbiol 73, 7169–7176.[CrossRef] [Google Scholar]
  12. Rheinheimer, G.(1980).Aquatic Microbiology. 2nd Edn. New York: Wiley.
  13. Roller, C., Wagner, M., Amann, R., Ludwig, W. & Schleifer, K. H.(1994).In situ probing of Gram-positive bacteria with high DNA G+C content using 23S rRNA-targeted oligonucleotides. Microbiology 140, 2849–2858.[CrossRef] [Google Scholar]
  14. Sekar, R., Pernthaler, A., Pernthaler, J., Warnecke, F., Posch, T. & Amann, R.(2003). An improved protocol for quantification of freshwater Actinobacteria by fluorescence in situ hybridization. Appl Environ Microbiol 69, 2928–2935.[CrossRef] [Google Scholar]
  15. Stamatakis, A., Hoover, P. & Rougemont, J.(2008). A rapid bootstrap algorithm for the RAxML web-servers. Syst Biol 57, 758–771.[CrossRef] [Google Scholar]
  16. Tamura, K., Dudley, J., Nei, M. & Kumar, S.(2007).mega4: Molecular evolutionary genetics analysis (mega) software version 4.0. Mol Biol Evol 24, 1596–1599.[CrossRef] [Google Scholar]
  17. Warnecke, F., Amann, R. & Pernthaler, J.(2004). Actinobacterial 16S rRNA genes from freshwater habitats cluster in four distinct lineages. Environ Microbiol 6, 242–253.[CrossRef] [Google Scholar]
  18. Warnecke, F., Sommaruga, R., Sekar, R., Hofer, J. S. & Pernthaler, J.(2005). Abundance, identity and growth state of Actinobacteria in mountain lakes of different UV transparency. Appl Environ Microbiol 71, 5551–5559.[CrossRef] [Google Scholar]
  19. Wu, Q. L., Schauer, M., Kamst-Van Agterveld, M. P., Zwart, G. & Hahn, M. W.(2006). Bacterioplankton community composition along a salinity gradient of sixteen high-mountain lakes located on the Tibetan Plateau, China. Appl Environ Microbiol 72, 5478–5485.[CrossRef] [Google Scholar]
  20. Wu, Q. L., Zwart, G., Wu, J., Kamst-van Agterveld, M. P., Liu, S. & Hahn, M. W.(2007). Submersed macrophytes play a key role in structuring bacterioplankton community composition in the large, shallow, subtropical Taihu Lake, China. Environ Microbiol 9, 2765–2774.[CrossRef] [Google Scholar]
  21. Zwart, G., Crump, B. C., Kamst-van Agterveld, M. P., Hagen, F. & Han, S.-K.(2002). Typical freshwater bacteria: an analysis of available 16S rRNA gene sequences from plankton of lakes and rivers. Aquat Microb Ecol 28, 141–155.[CrossRef] [Google Scholar]

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vol. , part 11, pp. 2864 - 2869

Cultivation of ‘ Planktophila limnetica’. Cultivation of the mixed culture containing ‘ Planktophila limnetica’. Maximum-likelihood tree calculated with 16S rRNA gene sequences. Neighbour-joining tree illustrating the phylogenetic position of ‘ Planktophila limnetica’ within the acI clade. . Sequences containing the oligonucleotide sequence 5′-GAAACTTGGTGGCATCRCCG-3′ diagnostic for the acI-AII cluster represented by ‘ Planktophila limnetica’.

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