文蛤闭壳肌酶法水解工艺研究

[目的]探讨文蛤闭壳肌酶法水解蛋白液制备的最佳工艺。[方法]以加酶量(木瓜蛋白酶)、pH、温度为因素采取3因素3水平的设计方法对文蛤闭壳肌进行水解。[结果]以水解率为指标,得到各因素对文蛤闭壳肌酶法水解影响的大小顺序为加酶量﹥pH﹥温度。最佳水解工艺条件为加酶量8 000 U/g原料,pH 5.5,温度50℃,优化方案的水解率为32.4%。[结论]研究为文蛤闭壳肌的综合利用提供了一定的科学依据。     

蛋白酶对文蛤肉水解效果的研究

本文探讨了木瓜蛋白酶、胰蛋白酶、精制中性蛋白酶、酸性蛋白酶、复合蛋白酶和风味蛋白酶等6种蛋白酶对文蛤肉的水解效果,以文蛤肉水解液的水解度、氮收率及水解得率为指标,并对酶解液进行感官鉴评和风味评分,结果表明精制中性蛋白酶、胰蛋白酶和风味蛋白酶为适用于文蛤肉水解的蛋白酶。     

菲律宾蛤仔高密度育苗技术

设计和制造了可以大规模应用于菲律宾蛤仔（Ruditapes philippinarum）等经济贝类苗种生产的高密度幼体培育系统、高密度稚贝培养系统,并建立了与之相配套的贝类育苗新工艺。克服了传统育苗方式占地面积大、生产效率低、种苗质量和产量不稳定的弱点,具有低消耗、高质量和高效益的突出特点,是贝类育苗工艺的变革。利用这一育苗技术,可以充分发挥高密度、集约化生产的优势,通过对苗种培育过程中水质、饵料和环境条件的全面控制,消除或减少敌害生物的影响,提高幼体的抗逆能力,从而杜绝抗生素的使用;在降低育苗生产的环境污染同时,向养殖户提供健康、优质的贝类苗种,是一种与环境相协调的、可持续的水产苗种培育模式。     

Estimating clam yield potential in the Sacca di Goro lagoon (Italy) by using a two-part conditional model

The assessment of clam yield potential and the identification of suitable sites for clam rearing are a necessary step to improve the economic and environmental sustainability of the exploitation activities in a regulated fishery. We discuss the development, validation and application of a method for estimating the clam yield potential of a northern Adriatic lagoon (Sacca di Goro, Italy) by combining logistic and ordinary regression. Clam yield potential was derived on the basis of six environmental parameters, namely sediment type, dissolved oxygen, salinity, hydrodynamism, water depth and chlorophyll “a”. Density data were positively skewed and contained a substantial proportion of zero values due to the patchy-distribution of Tapes philippinarum. The original data set was divided in two parts: one indicating if T. philippinarum was present or not and the other indicating the abundance of the species when it was present. The presence data was modelled by using logistic regression and the abundance data was separately modelled by using ordinary regression. The two models were then combined to identify suitable sites, to compute the expected clam yield potential in the Goro lagoon and to define the role of each environmental parameter in determining clam presence and abundance. The two-part model was then validated on a further data set (R² = 0.87). Data on environmental parameters gathered in 15 sampling sites were interpolated via a nearest neighbour algorithm so as to derive maps of each environmental parameter for the whole lagoon. Finally, the two-part model was applied to derive the thematic maps of suitable sites for clam rearing and the corresponding yield potential.We claim that this reasonably rapid and cost-effective approach provides a rigorous framework for a fair partition of harvesting concessions among competitive users and for a substantial improvement of transparency in the decision-making process.     

水环境中Cd和Cu污染对监测生物河蚬积累效应的影响

以河蚬作为指示生物,采用室内培养方法,研究了不同浓度的 Cd和 Cu的单独及联合作用的毒性效应.结果显示,在水体中浓度为 10、 20、 30、 40、 50 μ g· L-1的 Cd与 Cu单独作用下,河蚬体内 Cd与 Cu的含量分别与其在该环境中的暴露时间和浓度呈显著正相关.在同样浓度的 Cd与 Cu共同存在的环境中,河蚬体内的 Cd与 Cu的含量仍与环境中该物质的浓度呈显著正相关,且随着暴露时间的延长均表现出对污染物质积累的增加.初步建议河蚬可作为淡水中重金属污染的监测指示生物.     

毛蚶组织切片的制作和观察

以毛蚶组织为试验材料,使用苏木精—伊红染色法(HE染色法),对毛蚶组织结构进行固定、切片、染色。将制作的组织切片放在显微镜下,观察其组织结构特点,探讨贝类组织切片制作的各个技术要素。     

Size-based physical properties of hard-shell clam (Mercenaria mercenaria) shell relevant to the design of mechanical processing equipment

The knowledge of physical properties of food products is of fundamental importance for efficient design, dimensioning, manufacturing and operation of different mechanical equipment used in the processing of these products. Clams of different sizes are utilized during processing, thus, all the sizes must be given adequate consideration for efficient processing. This study was conducted to investigate the size-based physical properties of hard-shell clam (Mercenaria mercenaria) shell relevant to the design of mechanical processing equipment. The sizes of the clam shells were identified and categorized as small, medium and large; and its effect on the physical properties were studied. The parameters investigated were length, width, thickness, arithmetic and geometric diameters, surface area, sphericity, aspect ratio, moisture content, bulk and true densities, porosity, clam shell weight, coefficient of static friction and angle of repose. Increase in the length and width of clam shells increased the arithmetic and geometric diameters, and the surface area, but decreased the sphericity and aspect ratio. Moisture content, bulk and true densities, porosity and clam shell weight increased with increase clam shell size. Coefficient of static friction of clam shell was highest on rubber surface and lowest on glass surface, and was positively correlated with size; while angle of repose decreased with size. There was an excellent agreement between the prediction of the normal distribution and the actual distribution of the clam shell sizes. All the parameters were significantly different with respect to clam shell size at p < 0.05, which makes a strong case for the consideration of clam shell size during processing.     

Fast detection of Vibrio species potentially pathogenic for mollusc

Vibrio tasmaniensis, Vibrio splendidus and Vibrio neptunius species were distributed worldwide and associated with aquaculture and have been reported as the cause of diseases in aquatic organisms. Polyphasic analyses for bacterial identification are not feasible for routine diagnostic because of the time involved. The aim of this study is to design three PCR primer sets that can assist with fast detection of these species. They were designed from the 16S ribosomal RNA gene, and PCR conditions were found. Each PCR test successfully identified all the tested strains of each target species. The combined specificity of V. tasmaniensis and V. splendidus primer sets offered the best coverage (86%) in terms of separating target organisms from other related species. The primer set of V. tasmaniensis showed a lower sensitivity limit (500 fg of DNA) than the V. splendidus set (1 pg) and both sets gave positive amplification using homogenized tissues from inoculated clams, with 10² and 10⁴ cfu/g of clam, respectively. The primer set of V. neptunius was highly specific, showing only cross-reaction with V. parahaemolyticus species from 44 tested species. Its sensitivity limit was 100 pg of DNA. A small number of biochemical tests were proposed concurrently with the PCR to differentiate the cross-reacting bacteria. The time of detection of the three tested species was reduced and the further affected animals can be diagnosed in a rapid fraction of time. The detection of virulent strains of V. tasmaniensis pointed to the risk of mollusc culture outbreaks.     

基于秩相关系数法分析评价广西合浦廉州湾增养殖区水质现状及其变化趋势

依据2004～2010年对广西合浦廉州湾增养殖区水质连续调查监测结果,选择高锰酸盐指数（CODMn）、无机氮（DIN）、活性磷酸盐（DIP）3个代表性指标作为评价因子,采用Danniel趋势检验的Spearman秩相关系数法对该增养殖区水质状况变化趋势进行研究分析。结果表明,合浦廉州湾增养殖区水质CODMn、DIP含量保持较平稳状态,而DIN含量则呈上升趋势。削减、控制外源性氮源施入仍然是今后环境治理工作的主要任务。     

小片与蚌间的关系对珍珠质量的影响

本研究采用褶纹冠蚌同一个体自体外套膜小片育珠,结果珍珠质量明显提高。采用三角帆蚌制取外套膜小片植入褶纹冠蚌。结果珍珠质量极差,大多数蚌产不出珍珠;采用褶纹冠蚌制取外套膜小片植入三角帆蚌,结果三分之一的蚌能得到质量高于褶纹冠蚌,产量高于三角帆蚌的珍珠。作者认为供片蚌和受片蚌间相适关系影响珍珠质量,研究如何提高褶纹冠蚌小片在三角帆蚌体内成珠的比率,在生产上是很有意义的。