极地产适冷脂肪酶菌株的酶学性质研究

从南北极环境样品中分离到7株产脂肪酶的细菌，经16SrDNA序列分析表明，这些细菌分别属于假交替单胞菌属（Pseudoalteromonas）和嗜冷杆菌属（Psychrobacter）．采用p-NPP法对这7株细菌所产的脂肪酶进行酶学性质研究，结果显示这些酶的最适作用温度在30～40cC、最适作用pH值在7—8之间，在低温下能保持较高的剩余活力，对热敏感，属于适冷脂肪酶．其中假交替单胞菌（Psychrobacter sp．7342）所产脂肪酶具有低温下酶的剩余活力高、有效作用温度和pH范围广、热稳定性较好及对多种金属离子抗性强等特点．该菌株能利用多种单一氮源和碳源产酶，最适产酶温度为25℃．在此基础上进行正交实验分析得到了该菌株的最佳发酵条件为：蛋白胨和淀粉含量各为1．33％，酵母膏含量为0．3％，温度为25℃．     

产淀粉酶的海洋曲霉菌的分离及酶学特性初步研究

从乐清湾红树林中分离获得2株产淀粉酶的真菌,经初步鉴定为曲霉属菌株,暂命名为曲霉5#和曲霉34#。对它们的生长温度、固体发酵时的产酶条件以及淀粉酶特性进行了初步研究。该研究结果表明,曲霉5#和曲霉34#的最适生长温度分别为30~35℃和25~30℃,最高生长温度分别为40℃和35℃,在10℃下均能生长。对两株菌进行固体发酵时其最佳培养时间为96 h。两株菌所产淀粉酶的最适pH值为7.0,最适反应温度为40℃;淀粉酶在50℃下仍能保持活力,60℃下酶活力开始下降,80℃时酶几乎失活;离子对淀粉酶的激活或抑制作用也相似。     

褐藻酸降解酶的制备及其性质研究

通过培养褐藻酸降解菌交替单胞菌(Alteromonas sp．)菌株H-1使其产酶，研究了该酶的性质。结果表明，该菌在25℃培养72h时产酶量最高。褐藻酸酶作用的最适底物质量分数为1％～2％。最适pH值为7．5，最适反应温度为40℃，温度升高酶活力急剧下降。     

对虾肠道中产蛋白酶菌株的筛选、鉴定及其产酶特性初步研究

本文对从健康的凡纳滨对虾、日本囊对虾肠道中初步分离得到的58株菌进行产蛋白酶能力测试,筛选得到产酶能力较强的3株菌,经生理生化和16SrDNA序列分析,初步鉴定为蜡样芽孢杆菌(SDMG9)、沙福芽孢杆菌(SDVG4)及蜡样芽孢杆菌(SQVG9)。生长及产酶条件优化表明菌株SDMG9的最适生长温度为28-40℃、pH为5.5-6.5、盐度为0-20,最适产酶温度为28℃、pH为9.5、盐度为0;菌株SDVG4的最适生长温度为28-40℃、pH为5.5-8.5、盐度为10-20,最适产酶温度为40℃、pH为5.5、盐度为10;菌株SQVG9的最适生长温度为28-40℃、pH为6.5-8.5、盐度为0-20,最适产酶温度为28℃、pH为7.5、盐度为10。经溶血试验与药敏试验检测表明三株菌均无显著溶血圈且所含耐药因子较少,不具备潜在的致病性,为后续对虾肠道益生菌的筛选及应用提供了科学依据。     

红树植物秋茄根际链霉菌(Streptomyces)146产生的几丁质酶

本文报道分离自厦门集美红树植物秋茄根际的链霉菌146菌株(Streptomycessp.146)产生几丁质酶(Chitinase)的条件及该酶的一些性质。结果表明,有机氮源能促进几丁质酶的合成,该菌在添加1.5%玉米浆或2.0%麸皮的诱导培养基中发酵的酶活性较高。产酶适宜培养基初始pH 为7.0,适宜温度30℃,发酵5～6d 酶活性达到高峰。该酶能被多种几丁质所诱导,是一种诱导酶,它对几丁质水解活性pH 范围为3～8.5,最适pH 为5.5,在pH 为4～7.5范围内较稳定。该酶在30～60℃之间酶活性随温度的升高而增高,而且酶稳定.     

褐藻酸降解菌的产酶条件研究

以海带病烂处分离到的别单胞菌属（Alkteromonas)的褐藻酸降解菌菌株A1为研究对象，在该菌的产酶条件进行了研究。结果表明，产酶的最适温度20℃，褐藻酸钠浓度（质量分数）0．5％－0．6％，pH7.5，盐度15，氮源为（NH4)2SO4，培养时间72h。     

河口区芦苇湿地一株耐盐纤维素降解菌的筛选鉴定

筛选高酶活、耐受高盐环境的纤维素降解菌,并对菌株产酶条件进行优化,为木质纤维素类物质的综合利用提供菌源。经刚果红水解圈初筛,纤维素酶活测定复筛,盐度梯度驯化,从辽河河口区芦苇湿地分离出一株高产酶的耐盐纤维素降解菌LHK-T3。经形态观察和16SrDNA序列分析,对菌株进行鉴定,经鉴定属于贪噬菌属(Variovoraxsp.)。探究菌株在高盐环境下的发酵过程中碳源、氮源、温度及pH对其生长量和产酶能力的影响。结果表明,菌株LHK-T3在盐度处于20~35条件下,产酶能力仍保持在最大产酶的50%以上,具有较好的耐盐性;在盐度为25的高盐环境下,最适碳源为麦麸、最适氮源为NH4NO3,在温度为30℃、pH为6.0,发酵时间为72h时,菌株生长速率最高,且具有最大内切葡聚糖酶(CMCase)酶活达到727.62IU/mL。从河口湿地土壤中分离筛选的高效耐盐纤维素降解菌LHK-T3具有较好的耐盐性,在高盐条件下木质纤维素降解等相关领域具有较好的应用前景。     

超嗜热古菌耐热酸性α-淀粉酶的发酵条件和酶学性质研究

对一株分离自深海热液口的超嗜热古菌(Thermococcus sp.HJ21)菌株进行了α-淀粉酶发酵条件的优化和酶学性质的研究.该菌株发酵9h后到达产酶高峰,产酶温度范围为60-90℃,其最适产酶温度为80℃.产酶pH范围为5.0-9.0,最适产酶pH为7.5.产酶NaCl浓度范围为0.5-4.0%,2.5%为最适宜NaCI浓度.糖原、淀粉、麦芽糖、酵母膏和蛋白胨促进产酶.该菌株产生的α-淀粉酶的分子量为51.4 kDa,酶的最适作用温度为95℃,在100℃仍有60%的酶活力.酶在90℃的半衰期为5 h,在100℃ 2 h仍有40%的残余酶活,酶的热稳定性不依赖Ca2+.酶的最适作用pH为5.0,pH 4.5仍有80%的酶活力,pH在5.5-7.0较稳定(80℃ 4 h).金属离子1 mmol/L的Mg2+、Co2+、Sr2+、Ba2+、K+、Na+对酶有激活作用,Cu2+、Pb2+、Hg2+、zn2+、Al3+对该酶均有抑制作用.     

海产品中蛋白酶产生菌的选育及产酶条件研究

从海产品虾和蟹中分离出蛋白酶产生菌共37株，其中YM007菌株蛋白酶生产活力较高，为194．6U／mL。以YM007为出发菌株，通过物理和化学方法复合诱变，获得了YM079号菌株。对其产酶条件的研究结果表明：它的最适产酶温度为35℃，最适生长pH为7．0，经过190r／min摇床培养36～40h，其产酶活力为240U／mL，比出发菌株的产酶活力提高了22％。该菌株经发酵的粗酶液最适作用pH为7．0，最适作用温度是45℃，是一种中温型中性蛋白酶。     

产低温纤维素酶海洋嗜冷菌的筛选及研究

从黄海的深海海底泥样中筛选出一株产纤维素酶的海洋细菌，初步鉴定为革兰氏阴性杆菌。该菌既能产生羧甲基纤维素酶，又能降解微晶纤维素，互有淀粉酶活。对该菌生长特征及所产纤维素酶的性质进行了初步研究。此菌最适生长温度为20℃，最高生长温度为40℃，在0℃也能生长，是典型的嗜冷菌。该菌所产纤维素酶最适反应温度为35℃，10℃仍有较高酶活，最适pH值为6．0，属酸性酶。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.