Studies On The Effects Of Microbial Ecological Agents For Shrimp

The composition and bacteria number of intestinal microflora of healthy and WSSV-infected shrimp, which were sampled from Qingdao, north China, were investigated and compared. Based on the results, four strains of probiotic bacteria with different active models were isolated and selected from the intestines and culturing water of shrimp. Their effects were studied and evaluated on improving the immunity and production performance of shrimp.The main results include: (i) there was significant difference on the intestinal microflora between the healthy and WSSV-infected marine shrimps; it suggested that there was a closed relationship between the intestinal microflora and shrimp health; (ii) the vibrios-antagonism bacteria XE-7, isolated from shrimp culturing water, was identified to be Arthrobacter nicotianae, which has antagonistic effects on three vibrios: Vibrio parahaemolyticus, V. anguillarum and V. nereis; (iii) the vibrios-antagonism bacteria XE-7 compounded to culturing water significantly improved the survival of shrimp (Penaeus chinensis) post-larvae by inhibiting pathogenic vibrios and improving water quality; (iv) the vibrios-antagonism bacteria XE-7 compounded to the diets of shrimp (P. vannamei) significantly enhanced the special growth ratio, intestine and hepatopancreas digestive enzyme activity, serum phosphatase enzyme activity, hemocyte counts, percentage phagocytosis, serum phenoloxidase activity, as well as respiratory burst activity; (v) the dietary supplementation of amylase-producing bacteria SE and proteinase-producing bacteria TE, isolated from shrimp intestine, was capable of catalyzing the activity of intestine digestive enzyme and immunity of shrimp (P. vannamei) significantly; (vi) likewise, isomalto-oligosaccharide and its stcatabolizing bacteria OJ, isolated from shrimp intestine, significantly increased the serum phenoloxidase enzyme activity and percentage phagocytosis of shrimp (P. vannamei); (vii) a feeding experiment was conducted to investigate the effects of microbial ecological agent composed of vibrios-antagonism bacteria XE-7, proteinase-producing bacteria TE, isomalto-oligosaccharide and its stcatabolizing bacteria OJ; the result demonstrated that this agent had comparable effects with p-glucan on improving the immunity and production performance of shrimp (P. vannamei); (viii) at the same time, the optimal levels of different dietary probiotics are recommended.