Hydrolase (beta-glucanase, alpha-glucanase, and protease) activity in Ariolimax columbianus (banana slug) and Arion ater (garden slug)

Carboxymethylcellulase (cm-cellulase), cellulase, chitinase, amylase, and protease enzymatic activity are found in the crop fluid and digestive gland of the pulmonate gastropods Ariolimax columbianus and Arion ater. The beta-glucanases (cm-cellulase, cellulase and chitinase) and alpha-glucanase (amylase) display acidic pH-activity optima (between pH 5 and 7) on their respective substrates (cm-cellulose, microcrystalline cellulose, chitin and starch). Protease activity (upon casein) displays a pH optimum of approximately 8.3. Comparative studies show higher specific enzyme activity in Arion ater than in Arliolimax columbianus for all five hydrolases studied. Incubation of the beta-glucanases for variable times at 50 degrees C indicates significant differences in stability between Ariolimax columbianus and Arion ater for the beta-glucanases (cm-cellulase, cellulase, and chitinase). Chromatography upon Sephadex G-100 reveals enzyme heterogeneity for the beta-glucanases in both species, with at least three enzyme components or complexes (of differing molecular weight) for each species that can hydrolyze cm-cellulase, cellulase, and chitinase. The beta-glucanases are apparently selective and specific for their respective substrates, with some cm-cellulase isozymes unable to digest native Cellulose and vice versa. Preliminary evidence for the presence of cellulose digesting prokaryotes in the crop fluid of Arion ater is presented. (C) 1991 Elsevier Science Inc.