Potential of using Daphnia magna (crustacea) developing in an aerated waste stabilisation pond as a commercial source of chitin

The potential of using the planktonic crustacean Daphnia magna as a commercial source of chitin was studied on the basis of the estimation of the amount of chitin produced annually by this species and the specifications of this kind of chitin. D. magna was found to have a significant chitin content, ranging from 3% to 7% of the body dry weight. During three consecutive years, chitin biomass (B) and daily somatic chitin production (daily P-SOM) were monitored in a 59,000-m(2) aerated waste stabilisation pond located in the Grand-Duchy of Luxembourg (Western Europe). These variables were found to vary a lot seasonally. Maximum values were observed in summer (B > 40 kg chitin; daily P-SOM > 20 kg chitin day(-1)). Annual somatic chitin production reached on average 1200 kg chitin year(-1). The amount of chitin generated by the moulting of the daphnids (i.e. chitin contained in the exuviae) can also constitute a significant source of chitin, reaching about 1220 kg chitin year(-1). Chitin was isolated from D. magna, following three different processing routes. The specifications of the isolated and purified chitin were similar to those of commercial chitin extracted from crabs and shrimps. The average molecular weight varied from 600,000 to 2,600,000 depending on the processing route, The isolated chitin had a low N content indicating a high degree of acetylation. (C) 2002 Elsevier Science B.V. All rights reserved.