Polysaccharolytic activity of the digestive enzymes of the macroalgal herbivore, Turbo sarmaticus (Mollusca: Vetigastropoda: Turbinidae)

A study of the polysaccharolytic enzyme activity of the mid-oesophageal and digestive gland of Turbo sarmaticus indicated that this mollusc possesses enzymes that can digest (completely or partially) storage and structural polysaccharides found in the Chlorophyta, Rhodophyta and Phaeophyta. Two levels of activity were detected in the digestive gland: 1) high apparent levels of enzyme activity (up to 180.8 (mu g(-1) ml(-1) h(-1)) mg(-1) protein) occurred on the storage polysaccharides found in the Rhodophyta and Chlorophyta; and 2) low levels of activity were detected on the storage polysaccharides (up to 34.1 (mu g(-1) ml(-1) h(-1)) mg(-1) protein) of the Phaeophyta and on all the structural polysaccharides tested ( < 45.5 (mu g(-1) ml(-1) h(-1)) mg(-1) protein). While the apparent enzyme activity of the mid-oesophageal gland on storage polysaccharides was always lower than that of the digestive gland, activity on some structural polysaccharides (xylan, 95.6 (mu g(-1) ml(-1) h(-1)) mg(-1) protein), alginic acid (112.8 (mu g(-1) ml(-1) h(-1)) mg(-1) protein) was higher. It is suggested that T. sarmaticus does not rely heavily on structural carbohydrates as a source of carbon. (C) 1999 Elsevier Science Inc. All rights reserved.