植食性海水鱼类消化利用大型海藻的机制与海藻资源的饲料化利用

Contraposing the current situation that the cultured marine fish are mainly carnivorous species, while the feed are mainly trash fish, both of which result in lag and unsustainable of mariculture. The present project plan to use the herbivorous newly cultured marine fish Siganus canaliculatus as the experimental animals, using different methods such as the histological, enzymological, physiological, biochemical, microbiological and molecular biological methods, try to know the characteristics of digestive physiology, and the species of important digestive enzymes and microorganisms, as well as the acting characteristics and relationship between digestive enzymes and microorganisms in the digestion of macro-alga, so as to clarify the mechanisms of digestion and utilization on alga in S. canaliculatus. Clone the genes of important digestive enzymes, produce the enzymatic and micro-ecological preparation for dietary additives, and establish the utilization technologies of low value seaweed for feed, and eventually develop a high-efficient and low-cost formulated diet on the basis of low value macro-alga materials. The results will be of important theoretical significance for the establishment of nutritional theory of herbivorous marine fish and for enriching fish nutrition physiology, and be benefic for the improvement and protection of oceanic environment due to the efficent utilization of large amount of low-value macro-alga and the development of seaweed aquaculture, and can also accelerate the exploitation of herbivorous marine fish, and thus be of huge economic, ecological and social benifit.

针对目前我国海水鱼养殖种类主要为肉食性鱼类、饵料主要为冰鲜杂鱼，海水鱼养殖业落后且难以可持续发展的现状，本项目拟以植食性的新兴海水养殖鱼类-黄斑蓝子鱼为对象，从消化道组织学、酶学、生理生化学、微生物学、分子生物学等不同水平上，弄清与大型海藻利用有关的消化生理特性、重要消化酶和微生物种类，探讨消化酶和微生物在海藻消化过程中的作用特性和相互关系，揭示蓝子鱼消化利用海藻的机制。克隆重要消化酶的基因，借助生物工程技术生产酶制剂和微生态制剂用于饲料添加剂；建立大型低值、残次海藻资源的饲料化利用技术；在此基础上，研制出基于海藻原料的高效、低成本饲料配方。项目成果不仅可以初步建立植食性海水鱼类的营养学理论体系，丰富鱼类营养生理学内容，具有重要的理论意义；也可提高大量低值、残次海藻的利用价值和促进海藻养殖业的发展，有助于改善和保护海洋生态环境；还可以加速植食性海水鱼类的养殖开发，经济、生态和社会效益巨大。

针对我国沿海大量低值残次海藻资源未被有效利用，导致资源浪费、污染环境等问题，本项目以植食性海水养殖鱼类-黄斑蓝子鱼等为对象，从消化系统组织形态学、酶学、生理生化学、微生物学等方面，探讨植食性海水鱼类消化利用大型海藻的机制，建立海藻的饲料化利用技术。项目按计划实施，达到预定目标，超额完成任务指标。主要结果有：(1)当蓝子鱼摄食海藻后，其消化系统在形态结构和生理功能等方面都发生一系列适应性变化，所需时间为3周左右。消化道变长，肠壁变薄且粘膜褶较丰富；淀粉酶、昆布多糖酶、纤维素酶等消化酶以及谷氨酰转肽酶、碱性磷酸酶等吸收相关酶的活力升高；肠道中的多糖降解菌数量增加。这些适应性变化有助于蓝子鱼对海藻等低能量食物的充分消化吸收，是其消化利用大型海藻的重要机制。(2)蓝子鱼对7种常见大型海藻的摄食偏好性顺序依次为浒苔、龙须菜、线形硬毛藻、石莼、 坛紫菜、羊栖菜、无柄珊瑚藻。海藻的生化成分、形态、质地等影响摄食偏好性。(3)研制出基于海藻原料的高效、低成本饲料配方3种。当饲料中添加一定量的非淀粉多糖酶时，黄斑蓝子鱼、黑鲷、白斑笛鲷幼鱼配合饲料中海藻粉的添加比例可由未添加酶制剂时的5%增加到15%，饲料成本降低约9%。饲料中添加海藻粉有助于提高鱼体的生长性能、抗菌力、健康水平及肌肉的营养品质。(4)项目完成后，已发表学术论文17篇，录用待发表论文3篇；其中SCI论文12篇，开放期刊英文论文1篇，中文7篇。参编专著一部，撰写其中约4.5万字内容。在9个学术会议上交流论文12篇。向世界基因库登记新基因序列3个；申请国家发明专利2件，已授权1件。培养研究生6名，青年教师2名。项目成果对于建立植食性海水鱼类的营养学理论体系、丰富鱼类营养生理学内容等具有重要理论意义；对于提高海藻资源的利用价值，保护生态环境，促进海水养殖业健康、可持续发展等具有重要的现实意义。