生物絮凝-罗非鱼养殖系统启动阶段絮体胞外聚合物、粗蛋白和总氨基酸变化

摘要

为了研究生物絮凝新吉富罗非鱼(Oreochromis niloticus)养殖系统的启动过程,本实验采用超声波法研究了该阶段絮体胞外聚合物(Extracellular Polymeric Substances, EPS)、粗蛋白和总氨基酸的变化情况.结果表明,控制养殖水体中溶氧在5 mg/L以上,水温25 ℃,由于碳源的添加不足,导致水体中硝酸盐发生积累;整个实验过程中,总磷的质量浓度持续增长;生物絮体的污泥活性指数(Sludge activity index, SVI30)先升高后降低;絮体中粗蛋白和总氨基酸含量不断增加,在第31天时,粗蛋白含量达到37.55%,与饲料中37.87%的粗蛋白含量接近,而总氨基酸含量达到了35%;絮体中 EPS主要分松散附着的胞外聚合物(Loosely bound EPS, LB-EPS)和紧密粘附的胞外聚合物(Tightly bound EPS, TB-EPS), LB-EPS以多糖为主,而TB-EPS以蛋白质为主;实验过程中,LB-EPS逐渐降低,TB-EPS则先升高后降低.%To study the start-up process of biofloc system for tilapia cultivation, current research explored water quality and settleability of bioflocs, extracellular polymeric substances (EPS), crudeprotein and total amino acid changes during the start-up period of a bio-floc system for tilapia cultivation.The results showed that the nitrate concentration was accumu-lated for the lack of the carbon source in the cultivation, of which the dissolved oxygen was controlled at about 5 mg/L and the temperature was at 25 ℃.During the experiment, the total phosphorus was persistently raised; the bio-flocs sludge-sludge activity index (SVI30) was at increased before decreasing.Crude protein and total amino acids content was in-creased.The crude protein content reached 37.55% in the 31st day, which was close to the content of 37.87% in the feed.The total amino acids content reached 35%.The EPS in bio-flocs mainly contained loosely bound EPS(LB-EPS) and tightly bound EPS (TB-EPS).LB-EPS and TB-EPS was mainly composed of polysaccharides and protein, Respective-ly.LB-EPS was gradually decreased during the experiment, while TB-TPS was increased be fore decreasing.