褐藻胶裂解酶产生菌Vibro sp．OY102的发酵条件优化

对海洋来源的Vibro sp．QY102的产褐藻胶裂解酶的发酵条件进行研究。结果表明，该菌株最适液体培养基成分为（w／v）：0．5％褐藻酸钠；0．4％蛋白胨；0．3％KH2PO4；0．7％K2HPO4·3H2O；2％NaCl；0．01％MgSO4·7H2O，pH=6．0。按3％的接种量接入培养基，30℃150r／min振荡培养120h，产酶达到10．2u／mL，为优化前的4．5倍。Mg^2＋是该菌株产酶所必需的，这在其他褐藻胶裂解酶生产菌株中未见报道。该菌株产酶发酵条件的研究，为褐藻胶裂解酶的大规模制备及应用奠定了基础。     

一株高效褐藻酸降解菌的筛选、鉴定及其发酵条件的优化

以褐藻酸钠为唯一碳源,从腐烂海带中筛选得到褐藻酸钠降解能力较强的菌株H4,经生理生化和16S rDNA序列分析鉴定该菌株属于交替单胞菌属(Alteromonas)。对菌株H4的发酵条件优化研究表明,H4的较优培养基组成为(w/v):褐藻酸钠0.6%、酵母粉0.5%、蛋白胨0.25%、NaCl 3%;较优培养条件为:培养温度28℃,初始pH7.5,接种量1.5%(v/v),培养时间48 h。Fe3+对交替单胞菌H4的产酶有明显的促进作用,这在其他褐藻酸裂解酶生产菌株中未见报道,而Cu2+对褐藻酸裂解酶的抑制作用高达45.78%。在优化后的培养条件下,粗酶液酶活达到146.45 U/mL,较优化前提高了39.4%。     

硫酸软骨素酶高产菌株的筛选、鉴定和发酵培养条件的研究

通过透明圈法从土样中初筛到2株产硫酸软骨素酶能力较高的菌株,经复筛,28号菌株产酶能力更强,对该菌株的形态特征和生理生化特性考察,初步鉴定为少动鞘氨醇单胞菌(Sphingomonas paucimobilis)。该菌株的发酵产酶条件研究表明,其产酶最适培养基组分为(%,w/v):酵母粉1.0,硫酸软骨素0.5,NaCl 0.5,KH2PO40.03,MgSO4.7H2O0.5,起始pH=8.5,其余为水。其最适产酶条件为:250mL三角瓶装液量40mL,1%(v/v)接种量,25℃,100r/min培养36h。在最适产酶培养条件下,菌株发酵液中硫酸软骨素酶的活力可达1.2U/mL。本研究筛选出产硫酸软骨素酶高的菌株,并为发酵法制备硫酸软骨素酶提供一定的实验依据。     

产甲壳素酶菌株HD001的发酵条件研究及酶的分离纯化

通过对降解甲壳素菌株 HD001 的发酵条件研究,确定了其产甲壳素酶最适培养基组分为 ( w/v ):( NH4 ) 2SO4 2.0%, NaCl 0.5%, K2HPO4 0.07%, KH2P O4 0.03%, MgSO4·7H2O 0.05% 以及葡萄糖 0.1%、酵母粉 0.3% 和胶体甲壳素 1.5%;最适产酶培养条件为:培养基起始 pH 值 6.0,培养温度 30 ℃,培养时间 120 h,发酵液酶活力达 376.2 U/mL.采用硫酸铵分级盐析、DEAE-纤维素离子交换层析、Sephacryl S-100 凝胶过滤层析对该酶进行纯化后,SDS-PAGE电泳显示单一条带,其相对分子质量约为 85.7 kDa.     

印尼热泉菌产热稳定褐藻胶裂解酶的酶学性质研究

以印尼热泉菌为材料,采用以褐藻酸钠为唯一碳源的培养基筛选产褐藻胶裂解酶的菌株,通过16S rDNA序列对产酶菌株进行种属鉴定,并通过硫酸铵沉淀、离子交换层析和凝胶过滤层析从高产酶菌株Aly-B5发酵液上清中纯化获得褐藻胶裂解酶,并对该酶的酶学性质进行了研究。结果表明:高产酶菌株经鉴定为Bacillus属;聚丙烯酰胺凝胶电泳(Sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE)显示纯化的褐藻胶裂解酶Aly-B5分子量为45kDa,该酶最适作用温度为65°C,75°C时的半衰期为110min,最适pH为7.0;Zn~(2+)、Mg~(2+)、Fe~(2+)对酶活具有明显的抑制作用,但该酶对乙二胺四乙酸(ethylene diamine tetraacetic acid,EDTA)并不敏感;同时,底物特异性实验表明Aly-B5是一种偏好降解聚古罗糖醛酸(poly G)的双功能裂解酶,降解产物主要是二糖。该酶优良的耐热性使其在海藻高值化利用领域具有潜在的应用前景。     

壳聚糖酶高产菌株的筛选和发酵条件的研究

从采集的土样中分离到1株产壳聚糖酶能力较强的菌株OU01,并对OU01进行了16S rDNA序列、形态及生理生化鉴定分析。16S rDNA序列分析表明该菌属于微杆菌属;该菌的形态特征与生理生化鉴定结果表明该菌与Microbacteriumsp.的相似性最高;因此将其初步鉴定为微杆菌属(Microbacterium)。同时对该菌的发酵条件进行了初步研究:该菌的最适培养基组成为(g/L):chitosan 10,(NH4)2SO420,MgSO4.7H2O 1.3,K2HPO4.3H2O 1.4,Glucose 1,Yeast extract 3,NaCl 5,起始pH=6.30。最适发酵温度为30℃,最佳发酵时间为96 h,在上述最优条件下,该菌株产酶达到118 U/mL。Microbacteri-umsp.OU01菌株为壳聚糖酶的研究和应用提供了新的来源。     

高产壳聚糖酶菌株的筛选和发酵产酶条件研究

为探讨专一性地降解甲壳质或壳聚糖的甲壳质酶或壳聚糖酶 ,从采集的土样中分离到 4株产壳聚糖酶能力较强的菌株 ,经摇瓶复筛 ,菌株YJ0 2产酶能力最强。对其发酵产酶条件的研究结果表明其产酶最适培养基组分为 (% ,w/v) :粉末壳聚糖 2 .0 ,葡萄糖 0 .1,NH4NO3 1.0 ,酵母提取物 0 .5 ,K2 HPO40 .0 7,KH2 PO40 .0 3 ,NaCl0 .5 ,MgSO4·7H2 O 0 .0 5 ,起始 pH 6.0。最适产酶培养条件是 :5 0 0mL三角烧瓶装瓶量为 15 0mL ,2 .0 % (v/v)接种量 ,3 0℃ ,15 0r/min培养 72h。在最适产酶培养条件下 ,72h时菌株YJ0 2发酵液中壳聚糖酶活力可达到 17.0 4U/mL。     

海洋弧菌QJH-12发酵产琼胶酶条件的优化

从中国南海海域分离到了一株具有较高琼胶降解活性的弧菌Vibrio sp.QJH-12,该菌株为革兰氏阴性菌,呈弯曲杆状,极生单根鞭毛,氧化酶阳性,过氧化氢酶阳性,O/129试验阳性。在琼胶平板上生长可软化琼胶,并在菌落周围产生凹陷。通过单因子实验和正交实验确定了培养基的最佳组成:琼胶2.0‰,柠檬酸三铵1.0‰,K2HPO41.0‰,NaCl1.0%。确定该菌株的最适发酵产酶条件:装液量为250mL的三角瓶中装入125mL的液体发酵培养基,培养基起始pH6.5,摇瓶转速150r/min,30℃发酵培养26h,发酵液的酶活力达到332U/mL。结果表明,该菌株从产酶活力和发酵特点等各方面具备工业化开发的潜力。     

琼胶降解菌F-6筛选、培养条件及对条斑紫菜(Porphyra yezoensis)细胞解离作用的研究

利用琼胶作为唯一的碳源从青岛太平角海域的海水和红藻样品中筛选分离得到一株高产琼胶酶的海洋菌F-6,对其最适的产酶条件,利用琼胶酶分离条斑紫菜的原生质体和原生质体的培养进行研究。结果表明,通过单次单因子和正交实验确定琼胶降解菌株F-6最适产酶培养基配方为(W/V):琼胶0.7%;酵母粉0.3%;蛋白胨0.5%;NaCl2.0%;K2HPO40.1%;CaCl20.02%;MgSO4·7H2O0.05%;FeSO4·7H2O0.002%;起始pH=7.5,最适的发酵产酶条件为:26℃培养36h。经条件优化后,粗酶液的酶活高达631.6U/ml。发酵液经过6000g离心30min得到粗酶液,粗酶液经过8k分离膜超滤,加入1mol/L渗透剂,0.22μm滤膜过滤除菌后降解条斑紫菜组织块,成功地分离得到大量的紫菜原生质体,其产率为3×106个原生质体/g新鲜紫菜组织。原生质体经初步培养发育成愈伤组织,其成活率为60%。     

一株海藻多糖降解菌的分离鉴定及产酶条件优化

从大型褐藻藻体分离获得一株具有高效降解琼胶和褐藻胶能力的革兰氏阴性菌菌株ST-6。16S rDNA序列分析结果表明,该菌株与海绵假单胞菌的相似度达到99%,NJ法构建系统进化树也与海绵假单胞菌归为一类,鉴定为海绵假单胞菌Pseudomonas pachastrellae ST-6。在2216E培养基、30℃培养条件下,海绵假单胞菌ST-6的生长曲线表明,接种10~48 h为菌株的指数生长期,48~72 h为生长稳定期。产酶结果表明,菌株ST-6在指数生长期时菌液的胞外琼胶酶相对酶活力较高,在接种48 h时,菌液的琼胶酶相对酶活力最高为249.15 U/m L。此外,发现菌株ST-6的琼胶酶和褐藻胶酶的分泌类型分别为非诱导型和诱导型。采用单因素分析法对其生长和产酶条件进行分析,结果表明,海绵假单胞菌ST-6最适生长条件为:温度25~35℃,33值5~9;最适产琼胶酶条件为:温度30℃,33值为7,琼胶浓度0.3%。最适产褐藻胶酶条件为:温度35℃,33值为9。在温度30℃、339和褐藻酸钠浓度0.15%的培养条件下,海绵假单胞菌ST-6获得最高胞外褐藻胶酶相对酶活力为135.54 U/m L。     

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.     

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。     

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.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Net Sand Transport Direction in a Tidal Inlet, using Foraminiferal Tests as Natural Tracers

The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance.