- International Journal of Systematic and Evolutionary Microbiology
- Volume 49, Issue 4
f Phylogenetic relationships of filamentous sulfur bacteria (Thiothrix spp. and Eikelboom type 021N bacteria) isolated from wastewatertreatment plants and description of Thiothrix eikelboomii sp. nov., Thiothrix unzii sp. nov., Thiothrix fructosivorans sp. nov. and Thiothrix defluvii sp. nov.
- Authors: Richard Howarth, Richard F. Unz, Elizabeth M. Seviour, Robert J. Seviour, Linda L. Blackall, Roger W. Pickup, J. Gwyn Jones, Junichi Yaguchi, Ian M. Head
- Author for correspondence: Ian M. Head. Tel: +44 191 222 7024. Fax: +44 191 222 5431. e-mail: email@example.com
- Int J Syst Evol Microbiol, October 1999 49: 1817-1827, doi: 10.1099/00207713-49-4-1817
- Subject: New Taxa - Proteobacteria
- Published Online:
Phylogenetic relationships of filamentous sulfur bacteria (Thiothrix spp. and Eikelboom type 021N bacteria) isolated from wastewatertreatment plants and description of Thiothrix eikelboomii sp. nov., Thiothrix unzii sp. nov., Thiothrix fructosivorans sp. nov. and Thiothrix defluvii sp. nov., Page 1 of 1< Previous page | Next page > /docserver/preview/fulltext/ijsem/49/4/ijs-49-4-1817-1.gif
The relationship of mixotrophic and autotrophic Thiothrix species to morphologically similar chemoorganotrophic bacteria (e.g. Leucothrix species, Eikelboom type 021N bacteria) has been a matter of debate for some years. These bacteria have alternatively been grouped together on the basis of shared morphological features or separated on the basis of their nutrition. Many of these bacteria are difficult to maintain in axenic culture and, until recently, few isolates were available to allow comprehensive phenotypic and genotypic characterization. Several isolates of Thiothrix spp. and Eikelboom type 021N strains were characterized by comparative 16S rRNA sequence analysis. This revealed that the Thiothrix spp. and Eikelboom type 021N isolates formed a monophyletic group. Furthermore, isolates of Eikelboom type 021N bacteria isolated independently from different continents were phylogenetically closely related. The 16S rRNA sequence-based phylogeny was congruent with the morphological similarities between Thiothrix and Eikelboom type 021N. However, one isolate examined in this study (Ben47) shared many morphological features with the Thiothrix spp. and Eikelboom type 021N isolates, but was not closely related to them phylogenetically. Consequently, morphology alone cannot be used to assign bacteria to the Thiothrix/type 021N group. Comparative 16S rRNA sequence analysis supports monophyly of the Thiothrix/type 021N group, and phenotypic differences between the Thiothrix spp. and Eikelboom type 021N bacteria are currently poorly defined. For example, both groups include heterotrophic organisms that deposit intracellular elemental sulfur. It is therefore proposed that the Eikelboom type 021N bacteria should be accommodated within the genus Thiothrix as a new species, Thiothrix eikelboomii sp. nov., and three further new Thiothrix species are described: Thiothrix unzii sp. nov., Thiothrix fructosivorans sp. nov. and Thiothrix defluvii sp. nov.
The GenBank accession numbers for the 16S rDNA sequences determined in this study are L79961-L79968, AF126148-AF126155 and AF127020.
© 1999 International Union of of Microbiological Societies | Published by the Microbiology Society
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