Widespread distribution of cellulase and hemicellulase activities among aquatic invertebrates

Cellulase and hemicellulases (mannanase, xylanase, xyloglucanase, and licheninase) activities were measured in the extracts of 18 species of macrobenthos (an oligochaete, two polychaetes, two decapods, one amphipod, three bivalves, and nine gastropods) to check the relevance of macrobenthos to the breakdown process of hard-degradable carbohydrates derived from terrestrial plants. As a result, these enzyme activities were detected in all of the extracts of macrobenthos except for Tubificidae sp. High cellulase activities were detected in the extracts of the decapods (Neocaridina denticulate denticulate, Caridina multidentata) and the gastropods (Semisulcospira libertina, S. reiniana, Physa acuta, Terebralia palustris). However, only weak activities were detected in the polychaetes (Perinereis nuntia, P. aibuhitensis) and the bivalve (Ruditapes philippinarum). High mannanase and licheninase activities were detected in two decapod species (N. denticulate, C. multidentata), while high xylanase activities were seen in the gastropods (S. libertina, S. reiniana). High xyloglucanase activities were noted in the gastropod (T. palustris). These facts suggest that the activities of different types of hemicellulase were distributed rather unevenly among the macrobenthos. The present paper is the first to report the widespread distribution of cellulase and hemicellulase activities among ecologically important aquatic invertebrates, and the possible relevance of these species in the breakdown process of plant-derived hard-degradable carbohydrates.