APPLICATION OF YEAST GLUCAN AND BACTERINS FOR ENHANCED SEED PRODUCTION OF MACROBRACHIUM ROSENBERGII (DE MAN)

摘要

The extracellular glucan producing yeast Acremonium dyosporii was found to be a good source of β-1,3 and β-1,6-glucans, well known immunostimulant/modulant useful in penaeids and non-penaeids. On optimizing the yeast biomass production for glucan extraction, pH 4.0 was found to be the optimum and at this pH culturing of the organism was comparatively easier as the acidic pH prevented totally bacterial contamination during the period of incubation. For the extraction of β-1,3 and β-1,6-glucans a protocol was standardized based on the principles of alkali extraction. By this method an overall yield of 8-10% glucan on dry weight basis could be obtained consistently. The glucan prepared in this way was incorporated in egg custard alone and in combination with bacterins and were fed to larvae for a period of 20 days and the per cent survival and total post larval production were determined. The combination of bacterin and glucan gave better results with an output of 37 per cent post larvae. In the larval rearing tanks during the experiment the physicochemical parameters were within the tolerable limits, and among the heterotrophic bacteria Pseudomonas dominated. However, extensive field trials have to be conducted to ascertain the efficacy of glucan and bacterins in enhancing survival and post larval production of M. rosenbergii in hatcheries.