Monomer sequence and acetylation pattern in some bacterial alginates

The sequential structures and acetylation patterns of alginates from several strains of Azotobacter vinelandii and Pseudomonas species, including P. aeruginosa, P. putida, P. fluorescens, and P. mendocina, have been studied by 1H-n.m.r. spectroscopy. O-Acetyl groups were exclusively associated with the D-mannuronic acid residues and the degree of acetylation varied in the range 4-57%, depending upon the proportion of this acid in the polymer. 1H-N.m.r. spectroscopy of a naturally occurring and an artificially acetylated D-mannuronan made it possible to determine the degrees of acetylation at O-2, O-3, and O-2,3. The most conspicuous difference between alginates from A. vinelandii and the four Pseudomonas species was the complete absence of consecutive L-guluronic acid residues in the latter.