Fig. 4

Distribution and abundance of alginate lyases in alginate-utilising microorganisms. A Phylogenetic tree of alginate-utilising bacteria with the distribution and abundance of alginate lyases and transporters. In the CAZy database there are ~ 250 species with genome sequence information, and 46 representatives were used to construct the tree based on alignment of 16S rRNA gene sequences. Poly- and oligo-alginate lyases are listed separately and shown as Alys and Oals, respectively. In addition, outer and inner membrane transporters for substrate delivery were analysed and are shown as OMP and IMP, respectively. MFS, major facilitator superfamily; ABC, ATP-binding cassette transporter. B Composition of SusC and SusC-like. SusC mainly occurs in Bacteroidetes and contains three putative domains: a carboxypeptidase regulatory-like domain (CRLD), a plug domain (an independently folded subunit of the TonB-dependent receptor that acts as a channel gate and blocks the pore when the channel is bound by a carbohydrate substrate), and a TonB-dependent receptor domain (TBDR). SusC-like present in Gammaproteobacteria lacks an N-terminal CRLD domain