Phylogenetic trees showing the relationship of 16S rRNA gene sequences amplified from Sagami Bay Calyptogena sediment and microbial mat to those of representatives of bacteria (a) (CFB, Cytophaga–Flavobacterium–Bacteriodes group; G+, Gram-positive bacterial group) and archaea (b). The phenogram was constructed from a matrix of pairwise genetic distances by the maximum-parsimony algorithm and the neighbour-joining method. Representatives of the Gram-positive bacteria and Korarchaeota were used as the outgroup in the bacterial and archaeal trees, respectively. Bootstrap values greater than 50% are shown. Scale represents a 2% difference in sequence. Numbers in parentheses show clone numbers. Sample designations are the same as shown in Fig. 1. MG-1, marine group 1. SBC and SBM are Calyptogena sediment and microbial mat samples, respectively.