Recovery of Chitin and Protein from Shrimp Head Waste by Endogenous Enzyme Autolysis and Fermentation

The industrial processing of shrimp produces massive quantities of solid waste that is a notable source of animal protein, chitin, carotenoids, and other bioactive compounds that are not appropriately utilized. In the present study, chitin and protein extraction from shrimp head with autolysis and fermentation using Bacillus licheniformis were investigated. The results showed that when shrimp heads were autolyzed with a natural pH at 50℃ for 4 h, the total amino acid nitrogen in the supernatant was 5.01 mg mL^-1. Then, when a 50%(v/m) inoculum of the hydrolysate was incubated at 60℃ for 10 h, a deproteinization rate of 88.3% could be obtained. The fermented supernatant was processed into a dry protein powder, while the residues were demineralized by 10% citric acid for chitin. The recovered protein powder contained 5.5% moisture, 11.5% ash, and 66.7% protein, while the chitin contained 3.5% moisture, 2.1% ash, and 3.1% protein. In addition, amino acids, minerals, heavy metals, the degree of acetylation, microstructure, and Fourier-transform infrared(FT-IR) spectroscopy results were analyzed. Furthermore, the statistics of the large scale trial after treatment with 20 kg of shrimp heads were analyzed. Thus, this work made the shrimp waste utilization environmentally sound and valuable.     

基于裤式拖网法的虾拖网网囊网目选择性试验与分析

为研究虾拖网网囊网目对主要渔获种类的选择性,于2017年9月在南海区采用裤式拖网法进行选择性试验。在SELECT模型框架下,使用极似然估算法,结合单网次和联合网次的数据,同时考虑网次间差异,估算网囊对主要渔获种类的平均选择性。共完成14网次作业,其中对照网囊之间的渔获性能比较试验4次,试验网囊的选择性试验10次。研究表明:对照网囊的位置对其渔获性能无显著影响;试验网囊对刀额新对虾(Metapenaeus ensis)的网次50%选择体长(L 50)为78.84~92.09 mm,平均为82.38 mm,网次选择范围(SR)为5.01~11.32 mm,平均为6.39 mm,网次相对作业强度(p)为0.44~0.71,平均为0.52;试验网囊对黄斑蓝子鱼(Siganus oramin)的网次L 50为59.20~76.80 mm,平均为71.17 mm,网次SR为5.30~16.87 mm,平均为14.20 mm,网次p为0.43~0.71,平均为0.63。试验网囊对刀额新对虾的网次和平均L 50值均大于其首次性成熟体长(80 mm),可见试验网囊对刀额新对虾的资源利用是合理的。本试验的裤式拖网法和数据处理方法可为今后拖网选择性研究提供参考。     

对虾养殖实验围隔中的解氮作用氮输出

解氮作用是指微生物引导的结合态NO₃-转化为N₂O或N₂等一种或两种气体的非同化吸收过程,即NO₃-→、NO₂-→NO→N₂O→N₂[1].该过程是自然界许多水体中结合态NO₃转化为气态N₂的重要形式,结合态NO₃是水体初级生产的限制因素,解氮作用的中间产物N₂O是与大气臭氧层密切相关因子。因此,人们注重解氮作用的研究。     

In situ enzyme immunoassays with tissue smears to study horizontal transmission of BMNV in penaeid shrimp and in beach animals

INTRODUCTIONThedevelopmentofshrimpcultureshasbeenaffectedseverelybyviraldiseases(CatandSu,1993).Atpresent,however,thepathwayofvirustransmissiontopenaeidshrimpisnotunderstoodanditisthereforedifficulttopreventtheoccurrenceandspreadofshrimpviraldiseases.Toreducethelossescausedbyviralinfection,thedevelopmentofearlyandaccuratediagnostictechniquesisessential(Bruceetal.,1994;Changetal.,1993;Huangetal.,1995;Vickersetal.,1993).Anenzymeimmunoassaytechniquefordetectingbaculoviralmidgutglandnecrosi…     

生物安全性的不换水对虾养殖系统

1985年以来,在美国的一个研究所协会已经研究出一套与美国的商业机会与约束相一致的新的对虾养殖技术。在美国,土地和劳动力是很贵的,环境保护规则是很严格并且是强制执行的,因此,市场要求高质量产品的稳定供应。在美国已经建立海捕健康亲虾及遗传改良的健康亲虾培育系统。并建立起先进的对虾病害诊断技术及病害防治技术,例如新的对虾饲料及对虾养殖技术。但是近年来对虾病害在世界范围控制不住的传播,要求人们把病害排除在对虾养殖过程之外。研究结果表明常规的水交换已导致由进水而造成的污染,并使虾场暴露在进水中已存在致病的情况。使用高质量的对虾种苗及优质饲料,有证据表明在许多情况下可以减少换水量,甚至不换水。文中介绍了支持生物安全性的不换水对虾性成熟与繁殖及育苗与养殖的对虾养殖技术概念的一些研究发现。     

RNA干扰技术与对虾病毒病防治

RNA干扰,是1种由双链RNA引发的转录后基因沉默现象.作为1种有力的反向遗传学研究工具,RNA干扰被广泛用于阻断各种基因的表达.建立在RNA干扰技术基础上的基因治疗,被认为是治疗病毒性疾病的有效手段.在水产科学领域,RNA干扰在对虾病毒病控制上的应用近几年受到广泛的关注.病毒性疾病已经在世界范围内给对虾养殖业造成了严重的经济损失,目前还没有有效的控制手段.利用RNA干扰技术控制对虾病毒的侵染,是一个很有前途的方法.本文综述RNA干扰技术在对虾病毒病防治中的最新进展,并对RNA干扰技术控制病毒侵染的可能性进行探讨.     

A Study on the Contribution of Different Food Sources to Shrimp Growth in an Intensive Fenneropenaeus chinensis Pond

Stable isotope methods can be used to determine the food sources and prey items of aquatic organisms accurately andreliably.This study examined the relative contribution of artificial foods (the formulated feed and Artemia) and natural foods toshrimp growth in an intensive Fenneropenaeus chinensis pond by using carbon and nitrogen stable isotopes.The results showed that the nutrition utilization efficiency of the harvested shrimp was low,only 33.18% of feed nitrogen and 21.73% of feed carbon beingconverted to shrimp flesh.Our stable isotope results showed that the shrimp obtained nutrition for maximum growth from artificialfoods,whose contribution was 93.5%,with the remaining attributed to the natural foods.However,there was 0.94 t harvested shrimpderived from natural foods (the rest of 13.56t harvested shrimp derived from artificial foods) in lha intensive pond with a shrimpproduction of 14.50 tha-1.Therefore,unit area shrimp production can be increased by increasing the contribution proportion of natu-ral foods in intensive shrimp farming.     

牟氏角毛藻对对虾育苗水质及抗逆性的影响

在凡纳滨对虾((Litopenaeus vannamei)育苗水体中引入不同浓度的牟氏角毛藻(Chaetoceros muelleri),检测主要水质因子,测定凡纳滨对虾对主要环境因子抗逆性,研究微藻对水质和凡纳滨对虾抗逆性的影响。结果表明,不同浓度牟氏角毛藻可明显改善对虾育苗水体的水质,提高幼虾的抗逆性(P<0.05)。牟氏角毛藻浓度为0.6×108～1×108/L时,实验组氨氮含量比对照组降低37.29%～46.32%,亚硝酸氮含量降低48.65%～62.70%,化学耗氧量(COD)值降低9.99%～12.19%;实验组育苗成活率达78.7%～84.0%,对照组育苗成活率46.0%;在氨氮、亚硝酸盐氮、硫化氢、甲醛抗逆性实验中,实验组幼虾成活率分别为75%～80%、75%、75%～85%、65%～70%,均显著高于对照组(P<0.05)。     

虾池浮游微藻的种类组成、数量和多样性变动

报道了在集约化养虾中应用有益微生物制剂对虾池浮游微藻的影响,分析了整个养虾周期浮游微藻的种类组成、生物量、优势种及多样性指数的周期变化情况。结果表明,早期虾池浮游微藻细胞数量维持在1×103~3×103mL-1的水平,养殖中期开始呈指数增长状态,后期达到顶峰,并维持在70×103~160×103mL-1的水平,生物量比自然海区高。优势种类明显,前期为中肋骨条藻和伏氏海毛藻等硅藻类,后期则为绿球藻和栅列藻等绿藻类,水色及藻相呈良好状态,而不施加芽孢杆菌制剂的对照池则在后期出现较大比例的有害的蓝藻。虾池藻类多样性指数、均匀度指数和种类丰度均呈现前期高后期低的趋势,而优势度指数则相反,呈现前期低后期高的趋势。浮游植物的多样性指数为0.60~3.80,平均为1.88,均匀度指数为0.14~0.83,平均为0.45;种类丰度为0.80~2.46,平均为1.38;优势度指数在0.17~0.85,平均为0.41。多样性指数和均匀度均比粤东海域低,但优势度则甚高。     

对虾蛋白自溶制备ACE抑制肽的工艺条件优化

以凡纳滨对虾为原料，以ACE抑制率为指标，利用响应面法对虾肉蛋白自溶制备ACE抑制肽的工艺条件进行了优化，即在酶解条件（pH值、温度、虾头虾肉质量比）和ACE（Angiotensin I-converting Enzyme，ACE）抑制率之间建立了数学模型Y=23．59—0．21X1＋0．84X2＋0．85X3—0．71X1^2-0．94X2^2-1．06X3^2＋0．088X1X2—0．46X1X3-0．87X2X3。分析表明，在3个因素中，虾头与虾肉比例对ACE抑制率的影响最为显著。优化后的工艺参数为：pH7．35，温度57．2℃，虾头与虾肉比例为1：1。根据回归方程的预测结果，反应时间为4h，其ACE抑制率达41．9％。