title: Diversity, localization, and physiological properties of filamentous microbes belonging to Chloroflexi subphylum I in mesophilic and thermophilic methanogenic sludge granules.
abstract: We previously reported that the thermophilic filamentous anaerobe Anaerolinea thermophila, which is the first cultured representative of subphylum I of the bacterial phylum Chloroflexi, not only was one of the predominant constituents of thermophilic sludge granules but also was a causative agent of filamentous sludge bulking in a thermophilic (55 degrees C) upflow anaerobic sludge blanket (UASB) reactor in which high-strength organic wastewater was treated (Y. Sekiguchi, H. Takahashi, Y. Kamagata, A. Ohashi, and H. Harada, Appl. Environ. Microbiol. 67:5740-5749, 2001). To further elucidate the ecology and function of Anaerolinea-type filamentous microbes in UASB sludge granules, we surveyed the diversity, distribution, and physiological properties of Chloroflexi subphylum I microbes residing in UASB granules. Five different types of mesophilic and thermophilic UASB sludge were used to analyze the Chloroflexi subphylum I populations. 16S rRNA gene cloning-based analyses using a 16S rRNA gene-targeted Chloroflexi-specific PCR primer set revealed that all clonal sequences were affiliated with the Chloroflexi subphylum I group and that a number of different phylotypes were present in each clone library, suggesting the ubiquity and vast genetic diversity of these populations in UASB sludge granules. Subsequent fluorescence in situ hybridization (FISH) of the three different types of mesophilic sludge granules using a Chloroflexi-specific probe suggested that all probe-reactive cells had a filamentous morphology and were widely distributed within the sludge granules. The FISH observations also indicated that the Chloroflexi subphylum I bacteria were not always the predominant populations within mesophilic sludge granules, in contrast to thermophilic sludge granules. We isolated two mesophilic strains and one thermophilic strain belonging to the Chloroflexi subphylum I group. The physiological properties of these isolates suggested that these populations may contribute to the degradation of carbohydrates and other cellular components, such as amino acids, in the bioreactors.
authors.affiliation: Microbial and Genetic Resources Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1 Higashi 1, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamada
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sekiguchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Imachi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kamagata
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Ohashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Harada
mesh_terms: D041862:Chloroflexi / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D020459:Genes, rRNA; D014644:Genetic Variation; D006358:Hot Temperature; D017404:In Situ Hybridization, Fluorescence; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D013696:Temperature
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012722:Sewage