Bacteria and digestive enzymes in the alimentary tract of Radix peregra (Gastropoda, Lymnaeidae)

Abstract

The extracellular digestive enzymes cellobiase and chitobiase were quantitatively determined in the esophagus, stomach, and intestine of Radix peregra. Although both enzymes had comparable Michaelis constants between 16 and 32 μM liter-1, the enzyme activities were significantly higher for cellobiase (2 nanoKatals [nKat] from the whole gut tract) than for chitobiase (0.3 nKat). As became evident after a treatment with antibiotics, chitobiase was provided by bacteria and cellobiase was synthesized in the digestive glands of the animals. A lysozyme assay indicated that R. peregra was able to digest bacterial food.