Digestive Enzyme Capacity of Aquatic Organisms

Dear Colleagues,

In aquatic organisms, such as fish, crustaceans, and mollusks, the digestion of food polymers (mainly proteins, polysaccharides, and lipids) occurs in the digestive tract by the action of digestive enzymes, synthesized and secreted by the digestive organs (pancreas in fish, hepatopancreas in crustaceans, or digestive glands in mollusks). Food or environmental studies that use the digestive enzymatic activity as part of the response indicators generally quantify the specific activity (U/mg of protein) in the species, stages, or experimental treatments. The specific activity of digestive enzymes is a value calculated through the analysis of a natural digestive fluid (such as gastric juice or the digestive enzyme secretion of the pancreas in the intestine) or the analysis of an artificial enzyme extract (from the stomach, pyloric caecum, intestine, pancreas, gland, etc.), to evaluate the physiological response between species, stages of development, natural cycles (circadian, molting, etc.), or dietary or environmental treatments. In the case of digestibility studies (in vivo or in vitro), the digestive enzymatic capacity, defined as the number of digestive enzyme units available for the digestion of a food polymer, is of relevant importance. To determine the digestive enzymatic capacity, the enzyme units must be defined as the number of bonds hydrolyzed per unit of time, preferably in terms of μmoles of the hydrolyzed substrate or μmoles of the product released, by the hydrolysis of one micromole of bonds (peptide, glycosidic, or ester) in food polymers, such as protein polysaccharides or glycerides, under physiological conditions of temperature and pH. The digestive enzymatic capacity of aquatic organisms is expressed in terms of total enzyme units (U/organism, U/g of organism, U/digestive organ, U/g of digestive organ, etc.).

This research is of significant importance as it aims to study, describe, and use the digestive enzymatic capacity of aquatic organisms, both in the wild and in culture. Considering the digestive enzymatic capacity, in terms of total activity, as a response to various conditions and treatments, such as species conditions, stage of development, environmental conditions, eating habits, and environmental or nutritional treatments, is crucial for advancing our knowledge in the field of aquatic biology and nutrition. The target species for this study include fish, crustaceans, and mollusks, which are critical components of marine and freshwater aquatic ecosystems.

Dr. Héctor G. Nolasco-Soria
Guest Editor

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• aquatic organisms
• digestive capacity
• digestive ability
• total enzymatic activity (protease, lipase, amylase, trypsin, chymotrypsin, leucine amino peptidase, alkaline phosphatase, acid phosphatase, chitinase, etc.)
• U/organism
• U/digestive organ (stomach, piloric caeca, intestine, pancreas)