FIG. 4.

Phylogenetic tree based on partial 16S rRNA sequences, showing the phylogenetic positions of archaeal clones obtained from compartment 1 of the ABR on day 100. The tree was constructed by using distance matrix methods with the Jukes-Cantor correction and neighbor joining. Bootstrap values greater than 50% indicate areas of stable tree topology based on 1,000 bootstrap resamplings. Scale bar = 0.1 substitution per sequence position. The information in parentheses indicates the OTU for each clone and the total number of clones in each OTU. The accession numbers for the reference sequences are as follows: Pyrodictium occultum, M21087; Methanobrevibacter ruminantium, RDP Locus Mbb. rumina; Methanobacterium bryantii, M59124; Methanobacterium formicicum, M36508; Methanosaeta thermoacetophila, M59141; Methanosaeta concilii, M59146; Methanococcoides burtonii, X65537; Methanomethylovorans hollandica, AF120163; Methanosarcina barkeri, M59144; Methanosarcina mazei, AJ012095; Methanomicrobium mobile, M59142; and Methanospirillum hungatei, M60880.