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Applied and Environmental Microbiology, October 2006, p. 6780-6788, Vol. 72, No. 10
0099-2240/06/$08.00+0 doi:10.1128/AEM.00891-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
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Tetsushi Inoue,1
Satoko Noda,1
Napavarn Noparatnaraporn,2
Toshiaki Kudo,1,3 and
Moriya Ohkuma1
Environmental Molecular Biology Laboratory, RIKEN, Saitama 351-0198, Japan,1 Department of Microbiology, Kasetsart University, Bangkok 10900, Thailand,2 Graduate School of Integrated Science, Yokohama City University, Kanagawa 230-0045, Japan3
Received 14 April 2006/ Accepted 8 August 2006
Recently we discovered two novel, deeply branching lineages in the domain Bacteria from termite guts by PCR-based analyses of 16S rRNA (Y. Hongoh, P. Deevong, T. Inoue, S. Moriya, S. Trakulnaleamsai, M. Ohkuma, C. Vongkaluang, N. Noparatnaraporn, and T. Kudo, Appl. Environ. Microbiol. 71:6590-6599, 2005). Here, we report on the specific detection of these bacteria, the candidate phylum TG3 (Termite Group 3) and a subphylum in the phylum Fibrobacteres, by fluorescence in situ hybridization in the guts of the wood-feeding termites Microcerotermes sp. and Nasutitermes takasagoensis. Both bacterial groups were detected almost exclusively from the luminal fluid of the dilated portion in the hindgut. Each accounted for approximately 10% of the total prokaryotic cells, constituting the second-most dominant groups in the whole-gut microbiota. The detected cells of both groups were in undulate or vibroid forms and apparently resembled small spirochetes. The cell sizes were 0.2 to 0.4 by 1.3 to 6.0 µm and 0.2 to 0.3 by 1.3 to 4.9 µm in the TG3 and Fibrobacteres, respectively. Using PCR screenings with specific primers, we found that both groups are distributed among various termites. The obtained clones formed monophyletic clusters that were delineated by the host genus rather than by the geographic distance, implying a robust association between these bacteria and host termites. TG3 clones were also obtained from a cockroach gut, lake sediment, rice paddy soil, and deep-sea sediments. Our results suggest that the TG3 and Fibrobacteres bacteria are autochthonous gut symbionts of various termites and that the TG3 members are also widely distributed among various other environments.
Published ahead of print on 21 August 2006.
Supplemental material for this article may be found at http://aem.asm.org/.
Present address: Department of Bioresource Engineering, Faculty of Agriculture, Yamagata University, Yamagata 997-8555, Japan.
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