ALGINASES FROM AZOTOBACTER SPECIES

Alginate lyases (alginases) have been prepared from strains of Azotobacter vinelandii and Azotobacter chroococcum in which they were located in the periplasm. The enzymes are present in wild-type strains of each species and in mutants failing to encyst or produce bacterial alginate. The lyases have been partially purified by ion exchange chromatography and by affinity chromatography on a matrix prepared from poly-D-Mannuronic acid. Although several bacterial and algal alginate preparations were degraded by the enzymes, highest activity was found on poly-D-mannuronic acid or on algal alginates with high mannuronic acid content. The major product from enzymes of either bacterium was an unsaturated uronic acid, when either alginates or poly-D-mannuronic acid were used as substrates. When tested against a series of algal alginates of increasing D-mannuronic acid content, the enzyme activity was highest against alginates of high D-mannuronic acid content, indicating that the enzymes are endo-D-mannurono-lyases. The alginases from the two bacterial species are not identical in their substrate specificity although both show the same generalized type of action.