Release of dissolved amino acids by flagellates and ciliates grazing on bacteria

Release of amino acids was examined in the laboratory in the form of dissolved primary amine (DPA) by two marine planktonic protozoa (the oligotrichous ciliate, Strombidium sulcatum and the aplastidic flagellate Pseudobodo sp.) grazing on bacteria. DPA release rates were high (19–25 × 10⁻⁶ and 1.8–2.3 × 10⁻⁶ μmol DPA cell⁻¹ h⁻¹ for flagellates and ciliates, respectively) during the exponential phase, when the ingestion rates were maximum. Release rates were lower during the other growth phases. The release of DPA accounted for 10 % (flagellates) and 16 % (ciliates) of the total nitrogen ingested. Our data suggest that the release of DPA by protozoa could play an important role in supporting bacterial and consequently autotrophic pico- and nanoplankton growth, especially in oligotrophic waters, where the release of phytoplanktonic dissolved organic matter is low.     

Cadmium accumulation by marine bacteria

Complexation of metals by marine bacteria is a well known phenomenon.¹ In the marine environment it may play a determining role in the mobilisation of metals and their transfer into sediments² or through food chains.³ However, only a limited number of studies have analysed metal binding mechanisms in marine bacteria, the cell structure of which depends more closely on the ionic composition of the environment.⁴ The aim of this work was to investigate the mechanisms responsible for the accumulation of cadmium by Gram negative marine bacteria.     

海洋异养细菌对无机氮吸收的研究

着眼于海洋异养细菌对无机氮的吸收研究,在不同的海区和河流中,通过对环境因素的分析和比较,发现不同环境影响因子作用下,异养细菌对无机氮吸收具有选择性,同时也发现,这与异养细菌本身的生理特性也有一定关系。     

Sensitive fluorometric procedure to determine individual amino acids in marine waters

Improved methodology for amino acid analysis coupled with semi-micro isolation techniques make feasible the measurement of individual amino acids from marine waters where sample volumes are limited (e.g., sediment pore water or culture filtrates). If a water sample contains more than 20 nmole 1^?1 of the respective compounds, dissolved free amino acids (DFAA) can be isolated from 5 ml of filtrate by cation exchange and measured on a sensitive amino-acid analyzer equipped with a fluorometric detector. Two ml generally provides sufficient sample to determine total dissolved amino acids. Lower concentrations of amino acids can be measured after concentration from larger samples (250 ml) by ligand exchange.     

A comparison of non-hydrolytic methods for extracting amino acids and proteins from coastal marine sediments

Advances in analytical techniques now allow for the potential analysis of intact peptides and proteins isolated from marine sediments. However, there is no established technique for the extraction of macromolecular materials from marine sediments. Six different methods for extracting the amino acid component from coastal marine sediments were compared to the standard hot acid hydrolysis technique for their percent recovery and amino acid composition. The standard hot acid hydrolysis on dried, whole sediments released the greatest concentration of total amino acids (PS-THAA; 3.52 mg gdwt^− 1 ± 10% (SMD)), yet this only accounted for 22% of the total nitrogen in Puget Sound sediments (Washington, USA). Repeated hydrolysis of the same samples did not improve the recovery of nitrogen by more than an additional 10%. Base extraction (0.5 N NaOH) was the second best method for recovering amino acid nitrogen, releasing 60% of the Puget Sound total hydrolyzable amino acids (PS-THAA) (corresponding to 13% of the total sedimentary nitrogen), and has the advantage that it does not rely on peptide hydrolysis to free the nitrogenous component from the sediment matrix. The amino acid distribution of the 0.5 N NaOH extract was not significantly different than the initial THAA. Other non-hydrolyzing methods released lower yields of amino acids (Triton X-100 ≥ hot water > 50 mM NH₄HCO₃ > HF), but might prove to be of use to investigators interested in specific fractions of sedimentary organic nitrogen because these four methods had distinctly different amino acid compositions (enrichments in basic amino acids and depletions in acidic amino acids). Treatments with HF both before and after traditional hydrolysis and/or extractions with base did not release any more of the sedimentary nitrogen. Our results are consistent with the hypothesis that a large fraction of the sedimentary nitrogen (TN) is protected within an organic matrix.     

重金属锌对海洋微藻藻源氨基酸产出的影响

锌是海洋微藻生长必需的金属元素,低浓度时可促进微藻的生长,而在高浓度时则表现为抑制其生长。受人类活动的影响,海洋中锌有富集增加的趋势,从而会对海洋微藻的生长产生影响。本论文探究了锌离子以及纳米氧化锌对硅藻中肋骨条藻(Skeletonemacostatum)和新月菱形藻(Nitzschia closterium)生长的影响,特别是对藻源氨基酸产生的影响,结果发现:纳米金属颗粒会通过释放离子的形式抑制海洋浮游植物的生长,中肋骨条藻比新月菱形藻对锌的响应更敏感。锌离子和纳米氧化锌可通过抑制浮游植物的生长来减少氨基酸的释放量和改变藻源氨基酸的种类,从而可能会对海洋氮循环过程产生影响。     

Experimental degradation of crude oil by marine bacteria

The ability of biodegradation for crude oil was examined for ten strains of marine bacteria. With regard to their degradation ability forn-alkanes the microorganisms tested could be divided into four groups, although the same result was not observed for microbial degradation of aromatic hydrocarbons obtained by the UV measurements.     

Degradation of lubricating oils by marine bacteria observed by quantitative mass spectrometry

Bacterial degradation of the hydrocarbons of lubricating oils was investigated by mass spectrometric analysis which gives both total amount and the composition of hydrocarbon types of residual oil. An unused lubricating oil, which mainly consisted of hydrocarbon types with only a small percentage ofn-alkanes, was degraded by marineBacillus sp. andPseudomonas sp. with 55 % and 25 % decreases in 10 days, respectively. Susceptibility of respective hydrocarbon types to biodegradation was in the following order: alkanes > non-condensed cycloalkanes, mono-aromatics > condensed cycloalkanes. A used lubricating oil of different brand showed a larger decrease than the unused oil. Both species of bacteria degraded large portions of alkane fraction of Arabian light crude oil.     

海洋生态系统净生产力研究进展

海洋生态系统净生产力 （net ecosystem production,NEP） 表示总初级生产力 （gross primary production,GPP） 和呼吸作用 （respiration,R） 过程之间的差异,它对碳收支平衡、海洋生态系统营养状态乃至气候变化等研究具有十分重要的指示意义。影响海洋 NEP 的因素有细菌、浮游生物、温度、太阳辐射、海冰融化、水团迁移、富营养有机质排放以及海水酸化等。目前计算 NEP 的方法可分为实验培养测定及数据模型计算两种。溶解氧培养法及同位素标记法等是经典的培养测定方法,但存在误差较大且重现性较差等问题。数据模型计算即借助养分质量平衡、响应面模型、O2/Ar 示踪等方法,通过将现场实测数据和生物地球化学模型结合,进行高时间分辨率的连续性观测,这也是目前测算 NEP 的主流应用手段。然而,相较于发达国家,我国在 NEP 的研究设备、技术、测定方法等方面仍存在一定差距。今后的研究重点将是建立 NEP 指标与表征海洋环境、气候变化之间的耦合关系以及 NEP 测定方法的改进,这将有助于深入理解和探索全球变化背景下海洋生态系统响应机制及变化趋势。     

牡蛎中氨基酸的傅里叶变换近红外光谱法快速定量测定

本文通过乘法散射校正(multiplicative scattering correction MSC)、一阶求导(1st Derivative,Db1)和Norris平滑等傅里叶变换近红外光谱定量分析数学模型,用交叉验证法确定了最优化建模参数,构建了牡蛎中氨基酸的快速定量测定方法。结果表明,牡蛎近红外光谱与氨基酸含量化学计量学拟合,线性相关系数为0.9860,交叉验证后线性相关系数为0.9794,对牡蛎样品进行检测,结果与传统的氨基酸分析仪的测试结果相比,相对误差小于2.5%,方法的精密度(RSD)小于1.0%,本文建立的傅里叶变换近红外光谱法定量分析牡蛎中氨基酸具有快速、准确、操作简便等特点,测定重复性优于氨基酸分析仪法。     

Inhibition of essential amino acid absorption in marine fishes by mercury

In polluted coastal waters marine fish can concentrate heavy metals in the intestine two or more orders of magnitude above those found in the water column and several-fold higher than the sediment level. These accumulations are primarily due to ingestion of contaminated food and drink. Relatively long residence time of gut content, low permeability coefficient of divalent cations through the lipid bilayers of membranes and profuse binding to the negative charge sites on the mucosal side of the gut, all combine to increase the concentration of heavy metals in the lumen. Do these high levels of heavy metals interfere with the normal processes of nutrient absorption? We have measured the effect of HgCl₂ and CH₃HgCl on the absorption of the essential amino acids, l-leucine, l-isoleucine, l-lysine and l-methionine, by the intestine of Fundulus and toadfish in vitro and in vivo. At concentrations expected in the gut, HgCl₂ can inhibit 20–80% of the leucine absorption; CH₃HgCl is less potent in this respect. While the action of Hg²⁺ appears to be limited to the luminal side, the more lipophilic CH₃Hg⁺ rapidly penetrates the epithelial cell layer and can inhibit the intracellular energy production needed for transport. The implications of these findings for growth and survival of marine fishes are discussed.     

海洋细菌素的研究进展

在自然环境中,有些微生物通过抑制或杀死另一种微生物的拮抗作用来获得竞争优势。有的细菌产生细菌素,可杀死与其亲缘关系相近种。细菌素通常是指由细菌分泌的、对同种或其他亲缘关系很近的细菌有抑制作用的一种蛋白类抑菌物质。细菌素的蛋白质性质以及多种明显区别于抗生素的优点,使其具有广阔的应用空间。     

Studies of nitrogen assimilation by marine phytoplankton and its implication in the nitrogen cycling in the sea

I present here a review of my work concerning nitrogen assimilation by marine phytoplankton. This opportunity was provided to me as the recipient of the Okada Prize for 1990 from the Oceanographical Society of Japan. Assimilation of nitrogenous nutrients by phytoplankton has received considerable research effort since it is an essential process in organic matter production in the sea surface. The use of¹⁵N technique is necessary for tracing nitrogen assimilation by natural marine phytoplankton, but nitrogen metabolism of heterogenous natural populations significantly complicates flow of isotope. Dilution of¹⁵N isotope by heterotrophic regeneration of ammonium causes underestimates of uptake rates. I made an evaluation of isotope dilution effects in available data sets of¹⁵N-ammonium uptake experiments in literature. Incorporated¹⁵N in particulates might revert back to dissolved organic or inorganic nitrogen. I conducted pulse-chase experiments which can quantify such loss of tracer. From these studies, a short term experiment with sufficient amount of tracer enrichment is found to overwhelm these problems. In such an experiment, however, the elevation of nutrient concentration by tracer addition may likely perturb the uptake process. An initial rapid uptake is expected if the population is nitrogen deficient, but I found that this phenomenon is not common to surface oligotrophic open oceans. Uptake rate from such an experiment, or capacity of nitrogen uptake, was obtained using surface waters from an extended area in the North Pacific, and its regional variability was discussed. In addition to overall¹⁵N uptake, time series analysis of intracellular¹⁵N partitioning between hot ethanol soluble and insoluble fractions was found to be useful. When¹⁵N-ammonium is added to nitrogen deficient cells of phytoplankton,¹⁵N is accumulated in the ethanol soluble fraction. Using cultured strains of marine phytoplankton, this accumulation was proved to be caused by the difference of rates of nitrogen uptake and nitrogenous macromolecule synthesis. Uptake rate per cell is relatively constant irrespective of nutritional status, but macromolecule synthesis decreases with nitrogen deficiency. This accumulation of¹⁵N in the ethanol soluble fraction was used as an index of nutritional status with respect to nitrogen of the natural populations of phytoplankton from the western North Pacific. The uptake capacity of nitrate was observed to be higher than that of ammonium in the regional upwelling around Izu Islands and during the spring bloom in Alaskan coastal water. The¹⁵N partitioning technique revealed that nitrate taken up was rapidly incorporated in the macromolecule fraction. This suggests that ammonium uptake is suppressed to be smaller than intracellular nitrogen assimilation, rather than that nitrate is taken up in excess and accumulates within the cell. Regulation of nitrate uptake by light intensity was also discussed in detail for the Alaskan data. Several other studies currently conducted are also mentioned.     

Light and substrate concentration relationships with marine ammonium assimilation and oxidation rates

Relationships between light intensity and substrate concentration and rates of assimilation and oxidation of ammonium by microorganisms were investigated at four stations off the Washington coast and three stations in the Southern California Bight. Ammonium oxidation rates were negatively correlated with light in the photic zone at all stations; light inhibition of nitrifying bacteria forms an important control over the depth distribution of ammonium oxidation activity. Both assimilation and oxidation were positively correlated with ammonium concentration at the Washington coast stations, where ambient ammonium concentrations were high. Light and ammonium assimilation rate were positively correlated at the Southern California Bight stations (within the photic zone; i.e., excluding depths greater than 150m), but unrelated at the Washington coast stations. Assimilation and oxidation have nearly opposite distribution patterns with depth in the water column, but phytoplankton and nitrifying bacteria probably compete for ammonium at depths near the bottom of the photic zone.     

Adsorption and desorption of proteins and polyamino acids by clay minerals and marine sediments

The adsorption and desorption of proteins and polyamino acids on illite, montmorillonite, goethite, and marine sediments was investigated. Three ¹⁴C-labeled hydrophilic proteins, Rubisco from C. reinhardtii, and GroEL and GroES from genetically modified Escherichia coli, were synthesized and purified for this study. The proteins were strongly and rapidly adsorbed by the clay minerals and marine sediments, and much of the adsorbed protein was not readily desorbed. Sodium dodecyl sulfate (SDS) extraction and separation by SDS-polyacrylamide gel electrophoresis (PAGE) and sucrose density gradients showed that Rubisco and GroEL were adsorbed on illite and sediments in their original forms. The apparent adsorption partition coefficients of the proteins were on the order of 10² l/kg on illite, 10³–10⁴ l/kg on goethite and montmorillonite, and 200 and 75 l/kg on Skan Bay and Resurrection Bay (Alaska) sediments, respectively. These partition coefficients are sufficiently large to permit sedimentary protein preservation via an adsorptive mechanism. Generally, basic polyamino acids had greater adsorption partition coefficients than acidic polyamino acids. Molecular size did not affect the electrostatic interaction between polyamino acids and mineral surfaces. Adsorption of bovine serum albumin (BSA) and negatively charged polyamino acids inhibited Rubisco adsorption, while positively charged cytochrome c and polyamino acids increased Rubisco adsorption. These results indicate that electrostatic interactions dominated in protein adsorption.     

海洋细菌抑菌活性菌株的筛选

从不同海区的海洋底质，生物样，水样中分离到480株海洋细菌，其中包括150株芽孢细菌和108株粪大肠杆菌，利用纸片法对其抑菌活性进行检测，结果表明：117株海洋细菌具有抑菌活性，占总分离菌株的24.4%；一般细菌，芽孢细菌，粪大肠杆菌的抑菌活性菌株分别占各供测菌株的17.1%,27.3%,35.2%；抑菌活性菌株的比例与样品来源密切相关，且各类海洋细菌的抗菌谱有很大的不同。     

Seasonal variations in the production and consumption of amino acids by coastal microplankton

A seasonal study on coastal microplankton was conducted in surface waters near Boothbay Harbor, Maine. Phytoplankton biomass, particulate production and extracellular organic release were examined in conjunction with microheterotrophic biomass and the uptake and respiration of amino acids. In situ dissolved free amino acid (DFAA) concentrations were also determined. Several phytoplankton blooms occurred throughout the year, in mid-summer, late autumn and in mid-winter. Heterotrophic activity and biomass paralleled phytoplankton extracellular release more closely than either phytoplankton particulate production or biomass. DFAA concentrations were not wholly dependent on extracellular release. Heterotrophic uptake did not appear to be dependent on DFAA concentrations but rather on rates of production of DOC by phytoplankton.     

海洋细菌对稀土元素铈的富集矿化过程研究

采用从深海沉积物样品中分离培养的海洋微生物,分别进行几种海洋细菌（Jeotgalibacillus sp., Paenisporosarcina sp., Sulfitobacter sp.）对稀土元素Ce的富集成矿过程的模拟实验。实验过程中利用ICP-MS、SEM、TEM等分析测试手段考察了微生物与稀土元素的相互作用过程。结果表明,三种海洋细菌对稀土Ce都有吸附富集作用,海洋细菌吸附富集稀土元素Ce的效率主要与细菌密度和稀土元素浓度有关,不同的海洋细菌对稀土元素的富集能力也有所不同。海洋细菌吸附富集稀土Ce并矿化的过程中,稀土元素Ce首先被吸附在细胞表面形成成核点,随后在细胞表面被矿化形成含稀土Ce的非晶相结构的矿物颗粒。通过考察海洋细菌对稀土Ce的生物成矿过程,进一步探讨了海洋微生物富集稀土成矿的过程和作用机制。     

Eutrophication and the rate of net nitrification in a coastal marine ecosystem

Rates of net nitrification were calculated for four large (13 m³) estuarine-based microcosms that had been subjected to inorganic nutrient enrichment. Calculated rates were based on two years of weekly nitrate and nitrite measurements and ranged from a maximum of 0·55 μmol NO₂₊₃⁻ produced l⁻¹ day⁻¹ in the control tank (no enrichment) to over 13 μmol NO₂₊₃⁻ produced l⁻¹ day⁻¹ in the most enriched tank (receiving 18·6 μmol NH₄ l⁻¹ day⁻¹). Almost all NO₂₊₃⁻ production was pelagic, little was benthic. Net NO₃⁻ production or net NO₂⁻ production dominated the net nitrification rates during different seasons. Good correlations were found between various oxidation rates and substrate concentrations. The calculated net nitrite production rates were 10 to 1000 times higher than previously reported rates for open ocean systems, demonstrating the potential importance of nitrification to estuarine systems.     

海洋贝类附生细菌区系分析及弧菌拮抗菌的筛选

对中国威海近海海域的紫贻贝、牡蛎、花蛤、毛蛤、扇贝、海兔等6种海洋贝类的附生细菌进行了分离培养,筛选得到100株细菌。从中选出45株有代表性的菌株,克隆其16SrDNA序列,进行分子鉴定。结果表明,这些细菌分布在 Arthrobacter, Bacillus, Bizionia, Brevundimonas, Cell...