Characterization of Digestive Enzymes from Adult Freshwater Pearl Mussel Chamberlainia hainesiana (Lea, 1856)

Abstract

Freshwater mussel Chamberlainia hainesiana is a vulnerable species in Thailand. The species has a lustrous nacreous shell that can be utilized for various purposes, and has a potential industrial use for producing freshwater pearl. Characterization of digestive enzymes would provide critical information prerequisite for studying the development of digestive enzymes during on–growing as well as for in vitro digestibility study important for the development of suitable artificial feed formulations for the commercial culture. The aim of this preliminary study was to determine optimum pH and temperature for three digestive enzymes: amylase, protease and lipase, from digestive gland including stomach of adult C. hainesiana under various pH’s (2–11) and temperatures (25–80°C). The results revealed at least three isoforms of amylase and protease, and at least 4–5 isoforms of lipase. No alkaline protease activity was detected. For future enzyme expression study, the suitable optimal conditions are 40°C pH 6 for amylase activity, 50°C pH 5 for protease activity, and 50°C pH 8 for lipase activity. At natural habitat of around 30°C, these enzymes are most active at pH 6, 6, and 8 (or 10), respectively, which are suitable conditions for future study on in vitro digestibility.