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1.
南大洋深海嗜冷菌2-5-10-1及其低温脂肪酶的研究 总被引：14，自引：0，他引：14
从南大洋普里兹湾的水样中筛选到一株产低温脂肪酶的深海嗜冷菌2-5-10-1,对其生长及产酶情况和酶性质做了初步研究.该菌株的最适生长温度为5℃,此时分泌的胞外脂肪酶最多;添加Tween80,橄榄油可显著促进脂肪酶的产生.该脂肪酶的最适作用温度为35℃,在0～20℃均保持较高的酶活性,在0℃可保持37%的相对酶活性;酶的最适作用的pH值为7.5,在pH6～9的范围内均存在较高酶活性;对热较敏感,在60℃保温15min可丧失50%以上的酶活性.该脂肪酶的催化作用不需要金属离子的参与,Cu2+和Zn2+对酶活有着强烈的抑制作用. 相似文献
2.
用酶标仪采用DTNB比色法测定栉孔扇贝(Chlamys farreri)血淋巴中谷胱甘肽还原酶(GR)的活性,并研究pH值、温度、激活剂和抑制剂对血清中该酶活性的影响及酶的热稳定性。结果表明,栉孔扇贝血细胞中GR比活力明显高于血清。血清中GR的最适pH值因缓冲液的不同而稍有差异:用PBS为缓冲液时,最适pH值为7.0;Tris-HCl为缓冲液时,最适pH值为7.5。酶的最适温度为60℃。将血清在20℃,30℃,40℃,50℃,60℃,70℃和80℃温度的水浴中放置30min后于20℃,pH7.5条件下测定该酶的热稳定性,结果显示50℃时酶的比活力最高,低于或高于此温度的酶比活力均下降,80℃时酶活性完全丧失。栉孔扇贝血淋巴中GR属中温型中性酶类,低温下较稳定。EDTA对该酶活性有促进作用,硫酸铜有抑制作用。 相似文献
3.
以酶学分析法研究了温度和pH对刺参(Apostichopus japonicus)肠道不同部位(前肠、中肠、后肠)4种消化酶活性的影响,并比较了其活性分布.结果表明,各消化酶随温度和pH均呈峰值变化:前肠、中肠和后肠蛋白酶均有2个活性范围,最适pH分别为3、9,脂肪酶活性的最适pH分别为3.5、4.0、4.0,褐藻酸酶活性的最适pH分别为4.0、4.5、4.5,果胶酶活性的最适pH分别为3.5、3.5、4.0;蛋白酶活性的最适温度均为45℃,脂肪酶活性的最适温度均为35℃,褐藻酸酶活性的最适温度分别为45℃、35℃、35℃,果胶酶活性的最适温度则分别为55℃、55℃、45℃;在各自最适温度和pH下,蛋白酶活性表现为后肠＞前肠＞中肠,脂肪酶活性表现为后肠＞中肠＞前肠,而前肠褐藻酸酶活性显著高于中肠、后肠(P＜0.05),果胶酶活性在肠道各部分相差不显著. 相似文献
4.
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. 相似文献
5.
用CMC平板筛选方法,从青岛近海海域海水中分离出一株产碱性纤维素酶的海洋菌株QM11,经16S rDNA鉴定,该菌株为Cytophaga fucicola.对该菌的生物学特性研究表明,其最适生长温度为27℃,生长温度范围为4～48℃,为耐冷菌;在pH7.0～8.0、含3.0%NaC1的培养基条件下,最适宜菌株生长和产酶;QM11所产碱性纤维素酶最适反应温度为40℃,最适反应pH为9.0,在碱性条件下具有较高的酶活性和较好的稳定性.Mn2+、Fe3+对酶反应具有促进作用,Cu2+、Pb2+对酶反应具有抑制作用. 相似文献
6.
7.
利用离子交换层析和凝胶过滤层析等方法,从日本(Charybdis japonica)血淋巴中分离纯化出了酚氧化酶,并以L-二羟苯丙氨酸(L-DOPA)作为特异性底物对其生化性质和酶性质进行了研究。结果表明,酚氧化酶和酚氧化酶原的分子质量分别为64.5 ku和69.5 ku。以L-DOPA为底物对酚氧化酶纯品进行研究发现,其最适pH值为6.0、最适温度为40℃。对底物L-DOPA和儿茶酚的米氏常数Km值分别为3.41和7.97 mmol/L。该酶对亚硫酸钠、苯硫脲极为敏感,对硫脲、苯甲酸非常敏感,表明该酶很可能是一种儿茶酚酶型的酶。此外,EDTA,DETC,Zn2 ,Mg2 和Cu2 均能显著抑制该酶活性,且10 mmol/L Cu2 能有效地回复该酶被DETC所抑制的酶活性,表明该酶确为一种Cu-金属酶。 相似文献
8.
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. 相似文献
9.
僧帽牡蛎碱性磷酸酶性质的研究 总被引：12，自引：2，他引：12
从僧帽牡蛎分离纯化出一种碱性磷酸酶,采用Sephadex G-200凝胶过滤柱层析法测得该酶分子量为1.57×10~5.以对硝基苯磷酸为底物,该酶的最适温度为43℃,最适pH值为10.0.在37℃和pH值为10.0的条件下,酶催化反应的米氏常数(K_m)为9.68×10~(-4)mol/dm~3,活化能(E_a)为45.85kJ/mol,温度系数(Q_(10))为1.80(30～40℃).对该酶的热稳定性研究表明:其在45℃以下较为稳定,50℃以上明显失活,并测定了该酶的热失活速度常数.金属离子对酶活力的效应研究结果表明:Mg~(2+)、Mn~(2+)、Ca~(2+)、Co~(2+)对酶有激活作用,Ag~+、Hg~(2+)、Zn~(2+)表现为抑制作用,Cd~(2+)几乎没有影响.Mg~(2+)是较有效的激活剂,表现为部分非竞争性效应,激活常数(K_a)为2.48×10~(-4)mol/dm~3,有Mg~(2+)存在时该酶活性中心的转换数量是无Mg~(2+)时的4.0倍.几种效应物对酶的抑制机理研究表明:HPO_4~(2-)、HAsO_4~(2-)、Cys为竞争性,其抑制常数分别为1.61、1.18和0.15mmol/dm~3;L-Phe为反竞争性,抑制常数为3.26mmol/dm~3. 相似文献
10.
冷活性纤维素酶性质研究 总被引：1，自引：0，他引：1
对海洋嗜冷菌MB1所产冷活性纤维素酶的性质进行了研究。该酶最适反应温度为35℃，0℃时残余酶活约为20％，最适pH值为6．0，在pH5～7．5范围内酶活均较高。该酶对热敏感，50℃保温2h，残余酶活为15％；60℃时，酶完全失活。 相似文献
11.
Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding. 相似文献
12.
Hoi-Soo Jung Kap-Sik Jeong Yong-Shik Chu Sung-Hyun Park Ki-Hyune Kim 《Marine Georesources & Geotechnology》2001,19(3):181-195
Grain size and water content in box-core sediments from the Clarion-Clipperton fracture zone (C-C zone) in the northeast equatorial Pacific were analyzed in detail to understand the downcore variations across a hiatus between Quaternary and Tertiary layers. Grain-size distributions in the topmost core sediments show two modes: a coarse mode (peaked at 50 μm) and a fine mode (at 2-25 μm). The coarse mode disappears gradually with depth accompanied by the dissolution of siliceous fossil tests, whereas the fine mode coarsens due to the formation of authigenic minerals. Water content increases abruptly across a color boundary between an upper pale brown layer and a lower dark brown layer that is the hiatus between Quaternary and Tertiary layers. Abundant smectites and microvoid molds, which are created by the prolonged fossil dissolution in the underlying sediment, are attributed for the abrupt downcore variation of water content. Overall variations in grain size and water content in the topmost core sediments in the western C-C zone are possibly constrained by the dissolution of biogenic siliceous fossils. Variations in geotechnical properties related to these changes must be considered in the design of nodule collectors. 相似文献
13.
Shigehisa Nakamura 《Marine Geodesy》2001,24(1):27-33
This article concerns an interrelation between the sea levels and the western boundary flow near a tectonic boundary in a local zone in the Northwestern Pacific. In this zone, sea level variations at stations located on the coast facing the Pacific are studied to find the interrelation between variations of the Kurosio flow as an index of the distance of the flow axis off a specific coast. The result is discussed after data processing of the monthly means of the sea levels, and a notice is taken of variations caused by active crustal upheavals during a seismic event, a local earthquake. 相似文献
14.
This study tests the hypothesis that the in situ void ratio of surficial marine sediments may be predicted from shear wave velocity-depth data with a reliability equal to that of other methods currently available. Shear wave velocity is fundamentally controlled by the number of grain-to-grain contacts per unit volume of material and by the effective stress across those contacts. In this study, three previously established empirical formulae are used to predict void ratio from velocity-depth data. Field data were acquired along a transect off the northern Californian coast across which water depth increased from 35 to 70 m and seafloor sediment type varied from sand to silty-sand, respectively. A towed seafloor sled device was used to collect shear wave refraction data, and a marked, systematic decrease in velocity was observed along the line, ranging from 35-70 m/s for the coarse, near-shore material to 25-40 m/s for the finer, offshore deposits. Void ratios predicted from these velocities were compared with data measured directly from box-core samples. Of the formulae used for prediction, two agree remarkably well with the control data. Both predicted and control values increase from 0.6-0.8 for the sandy material to 1.1-1.5 for the silty-sand. Thus, this study does not disprove the hypothesis set and demonstrates the potential of field shear wave velocity-depth data as a means of delineating spatial variation in void ratio for surficial marine sediments in a remote, nondestructive manner. 相似文献
15.
Particulate samples were collected from the Changjiang river system during a flood period, in May 1997, and POC, stable isotope and lipids associated with particles were examined. Results showed the decrease (0.84% ～ 1.88%) of organic carbon content from the upper reaches to the estuary.δ13C values of particulate organic carbon was in the range of -24.9×10-3 to -26.6×10-3, which were close to the isotopic signature of continental C3 vegetation. Total particulate n-alkanes concentrations varied from 1.4 to 10.1μg/dm3,or from 23.7 to 107μg/g of total suspended matter. Fatty acids were present in all the samples, from 1.4 to 5.4μg/dm3, with saturated and unsaturated straight-chain and branched compounds in the carbon number range from C12 to C30. Both δ13C and the ratio of carbon content to nitrogen content indicate the predominance of terrestrial inputs (soil organic matter) among the particles. The biomarker approach has been used to identify the relative portion of terrigenous and autochthonous fraction in the particulate samples. The distribution of fatty acids suggests a striking phytoplanktonic and microbial signal in most particle samples. The terrestrial alkanes are used to estimate the contribution of terrestrial inputs along the mainstream. 相似文献
16.
Andrzej Chybicki 《Marine Geodesy》2018,41(1):1-23
Current trends of development of satellite derived bathymetry (SDB) models rely on applying calibration techniques including analytical approaches, neuro-fuzzy systems, regression optimization and others. In most of the cases, the SDB models are calibrated and verified for test sites, that provide favorable conditions for the remote derivation of bathymetry such as high water clarity, homogenous bottom type, low amount of sediment in the water and other factors. In this paper, a novel 3-dimensional geographical weighted regression (3GWR) SDB technique is presented, it binds together methods already presented in other studies, the geographically weighted local regression (GWR) model, with depth dependent inverse optimization. The proposed SDB model was calibrated and verified on a relatively difficult test site of the South Baltic near-shore areas with the use of multispectral observations acquired by a recently launched Sentinel-2 satellite observation system. By conducted experiments, it was shown that the proposed SDB model is capable of obtaining satisfactory results of RMSE ranging from 0.88 to 1.23[m] depending on the observation and can derive bathymetry for depths up to 12m. It was also shown, that the proposed approach may be used operationally, for instance, in the continuous assessment of temporal bathymetry changes, for areas important in the context of ensuring local maritime safety. 相似文献
17.
N. H. Khadge 《Marine Georesources & Geotechnology》2000,18(3):251-258
As a part of the environmental impact assessment studies, geotechnical properties of sediments were determined in the Central Indian Basin. The undrained shear strength and index properties of the siliceous sediments were determined on 20 box cores of uniform dimension collected from various locations in five preselected sites. The maximum core length encountered was 41 cm and most of the sediments were siliceous oozes consisting of radiolarian or diatomaceous tests. The shear strength measurements revealed that surface sediments deposited in recent times (0-10 cm) have a shear strength of 0-1 kPa; this value increases with depth, reaching 10 kPa at 40 cm deep. Older sediments have greater strength because of compaction. Water content varies in the wide range of 312-577% and decreases with depth. The clay minerals such as smectite and illite are dominant and show some control over water content. Wet density, specific gravity, and porosity do not indicate any notable variation with depth, thereby indicating a uniform, slow rate of sedimentation. The average porosity of sediments is 90.2%, specific gravity 2.18, and wet bulk density 1.12 g/cm 3 . Sediments exhibit medium to high plasticity characteristics, with the average plasticity index varying between 105% and 136%. Preliminary studies on postdisturbance samples showed an increase in natural water content and a decrease in undrained shear strength of sediments in the top 10- to 15-cm layer. 相似文献
18.
J. N. Pattan Ch. M. Rao A. A. Migdisov S. Colley N. C. Higgs L. Demidenko 《Marine Georesources & Geotechnology》2001,19(3):155-165
The rare earth element (REE) distribution in nine deep-sea ferromanganese nodules and their associated siliceous sediments from the Central Indian Ocean Basin (CIOB) have been studied to elucidate the REE relationship among them. Total REE concentration varies from 398-928 ppm in the nodules and 137-235 ppm in the associated sediments, suggesting two- to four-fold enrichment in the nodules compared to associated sediments. REE of nodules and their associated sediments show a positive correlation, suggesting REE are supplied from a common source such as seawater. The positive correlation between REE of nodules and sediments from the CIOB is contrary to the competitive scavenging of REE between nodules and sediment in the equatorial Pacific Ocean. REEs in the nodules are carried by Fe, P, and Ti, whereas in the sediment they are carried by P and Mn phases. A similar REE fractionation pattern with middle REE enrichment over heavy and light REE in both the nodules and their associated sediment suggest fractionation is independent of REE abundance and their carrier phases. 相似文献
19.
Lori E. Fenstermacher Gregory B. Crawford Jeffry C. Borgeld Tristan Britt Douglas A. George Meredith A. Klein Neal W. Driscoll Larry A. Mayer 《Marine Georesources & Geotechnology》2001,19(2):135-145
Detailed acoustic surveys of benthic sediments were conducted in July 1995 and September 1998 in the vicinity of Humboldt Bay, California. During these surveys, a band of enhanced acoustic backscatter was observed offshore from the bay entrance, approximately parallel to the isobaths, in water depths ranging from 16-24 m. In order to assess the cause of the increase in backscatter levels, a more comprehensive study was conducted in August and September 1999 using 100 kHz side-scan sonar, bottom grab sampling and underwater video recording. New observations indicated that a dense population of sand dollars ( Dendraster excentricus ) coincided with the enhanced backscatter band. Compared to the two previous acoustic studies, the central section of the band expanded westward by 180 m and the southern section of the band shifted eastward by 160 m, possibly resulting from a change in the biological or physical factors which influence the location and breadth of sand dollars. The relationship between high sand dollar abundance and enhanced acoustic backscatter was further verified in the nearshore region off Samoa Beach California, where a dense, banded population of sand dollars was previously observed. Video footage confirmed the presence of a band of sand dollars, also nominally parallel to the isobaths, in water depths of 8-15 m. A band of enhanced backscatter coincided with the dense sand dollar population. The identification of dense aggregations of sand dollars through enhanced acoustic backscatter could lead to the use of acoustic techniques to study sand dollar distributions and abundance. 相似文献
20.
Vast reserves of marine minerals are known to occur within the Mexican Exclusive Economic Zone. These reserves include: (1) heavy mineral placers rich in titanium and iron along the coast of San Antonio del Mar, Baja California and the southern States of Oaxaca and Guerrero; (2) phosphorites, which represent the only source for superphosphate fertilizers along the Pacific coast off the Baja California peninsula and the Gulf of Tehuantepec; and (3) manganese oxide deposits in nodule and crusts located adjacent to the Clarion-Clipperton Zone and containing high concentrations of Cu + Ni + Co (up to 1.9%), which are essential for the steel and super-alloy industries. Few but important efforts toward surveying these deposits have been carried out by Mexican and international researchers. Relevant data generated by these investigations are reviewed here and put together in a single document. Adequate knowledge of Mexican mineral resources is essential for the development of management strategies when offshore mining starts during this century. Thus, the review discusses the economics inherent to ocean mining in Mexico, setting baselines for future exploration and development activities in the Mexican Exclusive Economic Zone. 相似文献