Abstract
Knowledge of specific enzyme activity, along with animal habits and digestive capacity is essential in formulating an appropriate diet for any species. In this study, we evaluated and characterized the activity of digestive enzymes present in the liver, intestine, and stomach of Paralichthys orbignyanus. The effects of pH and temperature on enzyme activity were also evaluated via the use of specific substrates. The use of specific substrates and inhibitors showed strong evidence of the presence of trypsin (BApNA= 0.51 ± 0.2 mU mg-1), chimotrypsin (SApNA= 2.62 ± 1.8 mU mg-1), and aminopeptidases (Leu-p-Nan =0.9709 ± 0.83 mU mg-1) in the intestine. Optimum pH for the activity of trypsin, chemotrypsin, leucino aminopeptidase, amilase, and pepsin were 9.5, 9.0, 8.0, 7.5, and 3.5, respectively, while optimum temperatures were 50, 50, 50, 40, and 45 °C, respectively. These results provide additional information regarding the biology of Brazilian flounder and can be used as a basis for further studies regarding fish feeding physiology.
Highlights
The Brazilian flounder, Paralichthys orbignyanus (Valenciennes, 1842) is a native species that inhabits coastal and estuarine areas from Rio de Janeiro – Brazil, to Mar del Plata – Argentina; is found in greater abundance in southern Brazil (Bianchini et al, 2010)
Trypsin (BapNA) and leucineaminopeptidase (Leu-p-Nan) activities were observed in crude extract of intestine
Results regarding the effects of pH on enzyme activity revealed increased activity of trypsin present in crude extract of the intestine at pH values ranging from 9-10 (Figure 1B), while higher enzymatic activity of both chymotrypsin and leucine aminopeptidase occurred in crude extracts of intestine at pH values ranging from 7.5 to 9.5 (Figure 1E and 1H, respectively)
Summary
The Brazilian flounder, Paralichthys orbignyanus (Valenciennes, 1842) is a native species that inhabits coastal and estuarine areas from Rio de Janeiro – Brazil, to Mar del Plata – Argentina; is found in greater abundance in southern Brazil (Bianchini et al, 2010). The flounder fishery industry in the southern region of Brazil has been considered an important resource, in the last few years has stagnated in capture rates (Brasil, 2010). Aquaculture for this species may be considered as an alternative resource to increase market supply (Sampaio et al, 2008). Feeding is one of the most expensive factors in aquaculture, often representing more than 50% of total costs (Alam et al, 2009) In this sense, it is important to offer well balanced diets that promote maximum fish growth while reducing production costs and nitrogenous residues to the environment (Gatlin, 2010). Therein, digestive enzyme patterns are correlated to fish feeding habits and digestive capacity (Kuz’mina et al, 2011)
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