Previous studies about enzyme additives for salmonids employed commercial proteases from bacteria, but research obtaining such enzymes from other organisms are scarce. We aimed to increase digestive protease activity in Oncorhynchus mykiss, by analysing potential sources of exogenous proteases generated from different seafood processing waste. To date, there is no information regarding the influences that exogenous enzymes have on the activity and integrity of endogenous enzymes in salmonids. The compatibility and interaction between endogenous and exogenous proteases were evaluated through protein hydrolysis and electrophoresis. We also evaluated the capacity of two types of microcapsules (Alginate–Chitosan and Alginate–Chitosan–Bentonite) to protect the protease activity after being exposed to the gastric environment of trout. The seafood wastes had activities around 0.23–2.53 U/ml at 15°C. Among all the exogenous proteases evaluated, P. granulosa's extract showed the best performance, followed by L. santolla's extract. Such extracts increased the protein hydrolysis to equal or higher levels than the commercial protease and did not alter the integrity of trout proteases. The optimal catalytic function at low temperatures of these extracts might be linked to the habitat of these arthropods. Alginate–Chitosan–Bentonite microcapsules are recommended in preference to Alginate–Chitosan capsules for delivery of enzymes in salmonids because they ensure the activity of exogenous proteases for longer in acid pH (6 vs. 4 h). This research promotes a re-evaluation of seafood processing wastes through the production of a potentially functional additive that may improve trout protein digestion.

中文翻译：

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来自海产品加工废料的外源蛋白酶作为虹鳟鱼养殖的功能性添加剂

以前关于鲑鱼酶添加剂的研究使用了来自细菌的商业蛋白酶，但从其他生物体中获取此类酶的研究很少。我们旨在提高Oncorhynchus mykiss 的消化蛋白酶活性，通过分析不同海产品加工废物产生的外源蛋白酶的潜在来源。迄今为止，没有关于外源酶对鲑鱼内源酶活性和完整性的影响的信息。通过蛋白质水解和电泳评估内源性和外源性蛋白酶之间的相容性和相互作用。我们还评估了两种微胶囊（海藻酸盐-壳聚糖和海藻酸盐-壳聚糖-膨润土）在暴露于鳟鱼胃环境后保护蛋白酶活性的能力。海鲜废物在 15°C 下的活性约为 0.23–2.53 U/ml。在所有评估的外源蛋白酶中，P. granulosa 的提取物表现出最好的性能，其次是L。 桑托拉提取物。此类提取物将蛋白质水解增加到与商业蛋白酶相同或更高的水平，并且不会改变鳟鱼蛋白酶的完整性。这些提取物在低温下的最佳催化功能可能与这些节肢动物的栖息地有关。推荐海藻酸盐-壳聚糖-膨润土微胶囊优先于海藻酸盐-壳聚糖胶囊递送鲑鱼中的酶，因为它们确保外源蛋白酶在酸性 pH 值下的活性更长时间（6 对 4 小时）。这项研究通过生产可能改善鳟鱼蛋白质消化的潜在功能添加剂，促进了对海产品加工废物的重新评估。