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Peptidase compensation in the digestive system of whiteleg shrimp Penaeus vannamei against dietary Kunitz‐type soybean trypsin inhibitor

Maytorena‐Verdugo, C.I., Córdova‐Murueta, J.H., García‐Carreño, F.L.
Aquaculture nutrition 2017 v.23 no.5 pp. 1095-1103
Litopenaeus vannamei, bioassays, chymotrypsin, enzyme activity, feces, proteolysis, serine, shrimp, soybean meal, soybeans, trypsin, trypsin inhibitors
The aim of this study was to assess the regulatory process of digestive peptidases of crustaceans in the presence of soybean trypsin inhibitor (SBTI). This naturally occurring inhibitor in soybean meal was used to inhibit the activity of digestive serine peptidases of the whiteleg shrimp Litopenaeus vannamei. In vitro, SBTI inhibited the total proteolytic activity and chymotrypsin activity by 65%. Trypsin activity was reduced by SBTI from 40% to 15% from 2 to 4 hr of incubation, which is the average time of residence of feed in the shrimp digestive system. During the bioassays, experimental groups were fed with increasing concentration of supplemental SBTI (1 g kg⁻¹ and 2 g kg⁻¹) and digestive gland and faeces of individual specimens were collected daily. At the end of the bioassay, peptidase activity of digestive gland and faeces was shown, revealing differential inhibition after feeding for 5 days. Several serine peptidases were observed in zymograms, showing a compensation effect on the digestive gland through the activation of peptidases from different catalytic type. These results provide evidence that the shrimp digestive gland can overcome the effect of SBTI by two adaptive mechanisms: synthesis of additional peptidases of the serine class and other unidentified peptidases.