| 1 | Extraction of flocculants from a strain of Bacillus thuringiensis and analysis of their properties显示文摘In a preliminary screening study,our laboratory isolated from the biofloc in aquaculture waters a strain of Bacillus thuringiensis,which produced highly efficient bio-flocculants.In the present study,we extracted the crude flocculants from this strain and analyzed their properties.Distribution analysis indicated that the flocculants were mainly distributed in the supernatant of the fermentation liquid.The flocculants were extracted using an ethanol extraction method,and the chemical compositions and morphology of the crude flocculants were analyzed using the Molish reaction,Fehling reaction,ninhydrin reaction,biuret reaction,phenol-sulfuric acid assay,Coomassie brilliant blue staining,ultraviolet scanning,infrared scanning and scanning electron microscopy.The carbohydrate composition of the polysaccharides in the flocculants was analyzed with thin layer chromatography.The results indicated that flocculants were solid substances with an ivory white color and their texture was loose and soft.Visualization under scanning electron microscopy revealed that their ultra-morphology consisted of small,long and fiber-like shapes.Chemical and physical analyses indicated that polysaccharides accounted for 34.5%of the components in the crude flocculants.The monosaccharides present in crude flocculants included mainly glucose,galactose and mannitose. | Jingrong Wu Guangjun Wang Zhifei Li Ermeng Yu Jun Xie Zonglin Zheng | 2017 | Aquaculture and Fisheries2017，2，4： | 1 |
| 2 | Effect of Bioactive Peptides(BPs) on the Development of Pacific White Shrimp(Litopenaeus vannamei Boone, 1931)显示文摘The present study was conducted to evaluate the feasibility of replacing fish meal(FM) with bioactive peptides(BPs) in diet of white shrimp(Litopenaeus vannamei). The changes in growth performance, body composition, non-specific immunity, and water quality were examined after the shrimp were fed four diets, in which 0%(control), 33.3%, 66.7% and 100% of FM was replaced by BPs, respectively. The groups were designated as Con, 1/3BPs, 2/3BPs, and 3/3BPs. A total of 720 shrimp with an initial body weight of 1.46 ± 0.78 g were fed the experimental diets for 56 days. The results revealed that: 1) the weight gain rate(WGR) in 1/3BPs, 2/3BPs, and 3/3BPs was significantly higher than that in Con(P < 0.05), while no significant difference was found on survival rate and feed conversion ratio(FCR); 2) the whole-body crude protein(CP) and crude lipids(CL) were significantly different among groups, while there was no significant difference between crude ash and phosphorus contents; 3) the levels of acid phosphatase(ACP), lysozyme(LZM), superoxide dismutase(SOD), phenol oxidase(PO) and bactericidal activity increased significantly with the inclusion of BPs; 4) in terms of water quality, no significant difference was found in p H and dissolved oxygen among diets during the whole experimental period. Moreover, even though nitrite and ammonium levels tended to increase with time, there was no significant difference among groups. The results indicated that BPs is an applicable alternative of protein source, which can substitute FM in the diets of L. vannamei; it is able to effectively promote growth performance and improve immunity. Moreover, BPs in the diets had no negative impact on water quality. | WANG Guangjun YU Ermeng LI Zhifei YU Deguang WANG Haiying GONG Wangbao | 2016 | Journal of Ocean University of China2016，15，3： | 0 |
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