Effect of pH, temperature and diet on digestive enzyme profiles in the mud crab, Scylla serrata

Pavasovic, Marko, Richardson, Neil A., Anderson, Alex J., Mann, David, & Mather, Peter B. (2004) Effect of pH, temperature and diet on digestive enzyme profiles in the mud crab, Scylla serrata. Aquaculture, 242(1-4), pp. 641-654.

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Commercial farming of the mud crab Scylla serrata is a significant industry throughout South East Asia. The limited scientific knowledge of mud crab nutritional requirements and digestive processes, however, is recognised as a major constraint to the future growth of this industry. To better understand the mechanisms of digestion in the mud crab we have analysed the diversity of digestive enzymes from the midgut (MG) gland. Significant protease, amylase, cellulase and xylanase activities were detected in soluble extracts from this organ. Temperature profiles for all enzymes were basically similar with optimal activities observed at 50 8C. Examination of pH tolerances revealed optimal activities for protease and amylase at pH 7 while maximum cellulase and xylanase activities were observed at pH 5.5. Under optimum conditions, protease and amylase activities were approximately two orders of magnitude greater than those seen for either cellulase or xylanase. Interestingly, MG extracts were able to liberate glucose from either starch or carboxymethyl (CM)- cellulose suggesting that a range of carbohydrates may be utilised as energy sources. The effects of dietary carbohydrates on feed digestibility, digestive enzyme levels and growth were also studied by inclusion of additional starch or CM-cellulose at the expense of casein in formulated diets. It was shown that amylase, cellulase and xylanase activities in extracts from the midgut gland were highest in mud crabs fed diets containing 47% carbohydrate. Based on these findings, we suggest that theability of the mud crab to modulate digestive enzyme activities may represent a mechanism to maximise access to essential nutrients when the dietary profile changes.

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36 citations in Web of Science®
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ID Code: 8597
Item Type: Journal Article
Refereed: Yes
Additional Information: For more information, please refer to the journal's website (see hypertext link) or contact the author.
Author contact details: n.richardson@qut.edu.au
Keywords: Mud crab, Scylla serrata, Protease, Amylase, Cellulase, Xylanase, Diet
DOI: 10.1016/j.aquaculture.2004.08.036
ISSN: 0044-8486
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > PHYSIOLOGY (060600) > Animal Physiology - Systems (060603)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Past > Institutes > Institute for Sustainable Resources
Copyright Owner: Copyright 2004 Elsevier
Deposited On: 13 Jul 2007 00:00
Last Modified: 29 Feb 2012 13:09

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