Impact of putative alginate polymerase subunits on alginate polymerase activity, alginate polymerization, and composition and correlation between polymerization and modification. (A) The values of molar fraction of G residue (FG), acetylation degrees (Ac. %), mean molecular masses, and alginate yield are aligned with the strains producing the respective alginates. (B) Correlation between degree of acetylation, epimerization, and molecular mass of alginate. Presumable features (no. 1 to 11) show protein complexes constituted by Alg8, Alg44, AlgG, and AlgX (see the legend at the top left corner of the plot). The subunit produced upon in trans complementation is shown as darker shape(s). Inactive AlgX(S269A) and AlgG(D324A) proteins are labeled as (Ac─) and (Ep─), respectively. The length of various alginates (PD) with respect to acetylation (Ac. %) and epimerization (FG) degrees are presented and proportionally illustrated for each feature. 300, PDO300; MCS5, pBBR1MCS-5; PD, polymerization degree; OM, outer membrane; CM, cytoplasmic membrane.