title: Community structure of Archaea and Bacteria in a profundal lake sediment Lake Kinneret (Israel).
abstract: The microbial community structure of an anoxic profundal lake sediment, i.e., subtropical Lake Kinneret, was analysed with respect to its composition by culture-independent molecular methods including terminal restriction fragment length polymorphism (T-RFLP) analysis, comparative sequence analysis, and quantitative real-time PCR. In particular we were interested in the structure, species composition, and relative abundance of the overall microbial community in the methanogenic sediment layer (0-10 cm depth). Pairwise comparison of archaeal and bacterial 16S rRNA gene T-RFLP profiles obtained from three independent samplings indicated stability of the microbial community. The numbers of Archaea and Bacteria, quantified by real-time PCR, amounted to about 10(8) and 10(10) 16S rRNA gene copies cm(-3) sediment, respectively, suggesting that Archaea may account for only a minor fraction (approximately 1%) of the total prokaryotic community. Hydrogenotrophic Methanomicrobiales and acetoclastic Methanosaeta spp. dominated T-RFLP profiles of the archaeal community. T-RFLP profiles of the bacterial community were dominated by Deltaproteobacteria, sulphate reducers and syntrophs in particular. The second most abundant group was assigned to the Bacteroidetes-Chlorobi-group. Only one bacterial group, which was affiliated with halorespiring bacteria of subphylum II of the Chloroflexi, showed variation in abundance within the sediment samples investigated. Our study gives a comprehensive insight into the structure of the bacterial and archaeal community of a profundal lake sediment, indicating that sulphate reducers, syntrophs, bacteroidetes, halorespirers and methanogens are of particular importance in Lake Kinneret sediment.
authors.affiliation: Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., 35043 Marburg, Germany.
authors.forename: Julia I K
authors.initials: JI
authors.lastname: Schwarz
authors.forename: Werner
authors.initials: W
authors.lastname: Eckert
authors.forename: Ralf
authors.initials: R
authors.lastname: Conrad
mesh_terms: D001105:Archaea / Q000145:classification* / Q000235:genetics; D001419:Bacteria / Q000145:classification* / Q000235:genetics; D044822:Biodiversity; D019641:DNA, Archaeal / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D018076:DNA, Complementary; D004275:DNA, Ribosomal / Q000235:genetics; D005618:Fresh Water; D018628:Gene Dosage; D020459:Genes, rRNA; D019015:Geologic Sediments / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D018076:DNA, Complementary; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S