Complete genome sequence of the marine planctomycete Pirellula sp. strain 1

Abstract

Pirellula sp. strain 1 ("Rhodopirellula baltica") is a marine representative of the globally distributed and environmentally important bacterial order Planctomycetales. Here we report the complete genome sequence of a member of this independent phylum. With 7.145 megabases, Pirellula sp. strain 1 has the largest circular bacterial genome sequenced so far. The presence of all genes required for heterolactic acid fermentation, key genes for the interconversion of C1 compounds, and 110 sulfatases were unexpected for this aerobic heterotrophic isolate. Although Pirellula sp. strain 1 has a proteinaceous cell wall, remnants of genes for peptidoglycan synthesis were found. Genes for lipid A biosynthesis and homologues to the flagellar L- and P-ring protein indicate a former Gram-negative type of cell wall. Phylogenetic analysis of all relevant markers clearly affiliates the Planctomycetales to the domain Bacteria as a distinct phylum, but a deepest branching is not supported by our analyses.

Fig. 1.

Structural representation of the Pirellula sp. strain 1 genome. Circle 1 (from the outside in), GC skew; circle 2, G+C content; circle 3, G+A content; circle 4, DNA curvature; circle 5, DNA bending; circle 6, DNA stacking energy; circle 7, codon adaptation index (CAI). The origin of replication (ORI) and the terminus (TER) are indicated. A and B indicate minor irregularities. Ochre, pink, and red represent high values; blue, light blue, and green show low values.

Fig. 2.

Circular representation of the Pirellula sp. strain 1 genome. Circles 1 and 2 (from the outside in), all genes (reverse and forward strand, respectively) color-coded by function; circle 3, predicted highly expressed (PHX) and predicted alien (PA) genes; circle 4, potentially eukaryotic or archaeal genes; circle 5, sulfatase, C1-metabolism, heterolactic acid fermentation, catalase, and ATP-synthase genes; and circle 6, transposase, integrase, and clusters of putative laterally acquired genes. The origin of replication (ORI) and the terminus (TER) are indicated.