Partitioning of copper among copper-binding proteins in the mussel Mytilus edulis exposed to soluble copper

Partitioning of copper among copper-binding proteins was evaluated in digestive glands of Mytilus edulis exposed to soluble copper. Groups of mussels were held in flow-through bioassay systems and exposed to 25 μg Cu liter^?1 for up to 21 weeks. At three-week intervals, groups of 25 mussels were removed and the digestive glands were analyzed for copper-binding proteins by gel-permeation chromatography and atomic absorption spectrometry.Chronic exposure to copper resulted in increased amounts of copper in the low molecular weight (LMW) protein fraction, which contains metallothioneins, and in the high molecular weight (HMW) protein fraction, which contains metalloenzymes. Concentrations of copper in the LMW protein fraction increased and then appeared to plateau with long exposure times, whereas those in the HMW protein fraction continued to increase with exposure time.     

Bacteria on petroleum globules in the Philippine sea in January, 1973

About 10⁶ of total bacteria (direct microscopic count) or heterotrophic bacteria (colony count with Medium 2216E) and about 10⁴ of petroleumlytic bacteria (oil-oxidizing bacteria) were enumerated per square centimeter of the surface of petroleum globules suspended in the topmost 10 meters of water from a station (22°00.2N, 125°51.9E) in the western North Pacific central water, where about 10⁷ of total bacteria, about 10³ of heterotrophic bacteria and about 10 of petroleumlytic bacteria were enumerated per liter of seawater.     

New and important roles for DMSP in marine microbial communities

The algal osmolyte dimethylsulfoniopropionate (DMSP) is recognised as the major precursor of marine dimethylsulfide (DMS), a volatile sulfur compound that affects atmospheric chemistry and global climate. Recent studies, using ³⁵S-DMSP tracer techniques, suggest that DMSP may play additional very important roles in the microbial ecology and biogeochemistry of the surface ocean. DMSP may serve as an intracellular osmolyte in bacteria that take up phytoplankton-derived DMSP from seawater. In addition, DMSP appears to support from 1 to 13% of the bacterial carbon demand in surface waters, making it one of the most significant single substrates for bacterioplankton so far identified. Furthermore, the sulfur from DMSP is efficiently incorporated into bacterial proteins (mostly into methionine) and DMSP appears to be a major source of sulfur for marine bacterioplankton. Assimilatory metabolism of DMSP is via methanethiol (MeSH) that is produced by a demethylation/demethiolation pathway which dominates DMSP degradation in situ. Based on the linkage between assimilatory metabolism of DMSP and bacterial growth, we offer a hypothesis whereby DMSP availability to bacteria controls the production of DMS by the competing DMSP lyase pathway. Also linked with the assimilatory metabolism of DMSP is the production of excess MeSH which, if not assimilated into protein, reacts to form dissolved non-volatile compounds. These include sulfate and DOM–metal–MeSH complexes, both of which represent major short-term end-products of DMSP degradation. Because production rates of MeSH in seawater are high (3–90 nM d⁻¹), reaction of MeSH with trace metals could affect metal availability and chemistry in seawater. Overall, results of recent studies provide evidence that DMSP plays important roles in the carbon, sulfur and perhaps metal and DOM cycles in marine microbial communities. These findings, coupled with the fact that the small fraction of DMSP converted to DMS may influence atmospheric chemistry and climate dynamics, draws attention to DMSP as a molecule of central importance to marine biogeochemical and ecological processes.     

Collection and detection of natural iron-binding ligands from seawater

Iron (Fe) is an essential element for the biochemical and physiological functioning of terrestrial and oceanic organisms, including phytoplankton, which are responsible for the primary productivity in the world's oceans. However, due to the low solubility of Fe in seawater, phytoplankton are often limited by their inability to incorporate enough Fe to allow for optimal growth rates in regions with dissolved Fe concentrations below 1 nM. It has been postulated that certain phytoplankton may produce compounds to facilitate the uptake of Fe from seawater to overcome this limitation. Dissolved Fe in the oceans is overwhelmingly complexed (>99%) by strong organic ligands that may control the uptake of Fe by microbiota; however, the identity, origin, and chemical characteristics of these organic chelates are largely unknown. Although it has been implied that some components of natural Fe-binding ligands are siderophores, no direct analyses of such compounds from natural seawater have been conducted. Here, we present a simple solid-phase extraction technique employing Biobeads SM-2 and Amberlite XAD-16 resins for concentrating naturally occurring dissolved iron-binding compounds from large volumes (>200 l) of seawater. Additionally, we report on the first successful determination of molecular weight size classes and preliminary iron-binding functional group characterization within those size classes for isolates collected from the surface and below the photic zone (150 m) in the central California coastal upwelling system. Electrochemical analyses using competitive ligand equilibration/adsorptive cathodic stripping voltammetry (CLE-ACSV) showed that isolated compounds had conditional Fe-binding affinities (with respect to inorganic iron—Fe′) of K_FeL,Fe′^cond=10^11.5–10^11.9 M⁻¹, similar to purified marine siderophores produced in laboratory cultures and to the ambient Fe-binding ligands observed in seawater. In addition, 63% of the extracted compounds from surface-collected samples fall within the defined size range of siderophores (300–1000 Da). Hydroxamate or catecholate Fe-binding functional groups were present in each compound for which Fe binding was detected. These results illustrate that the functional groups previously shown to be present in marine and terrestrial siderophores extracted and purified from laboratory cultures are also present in the natural marine environment. These data provide evidence that a significant fraction of the organic Fe-binding compounds we collected contain Fe-binding functional groups consistent with biologically produced siderophores. These results provide further insight into characteristics of the Fe-binding ligands that are thought to be important in controlling the biological availability of Fe in the oceans.     

北部湾北部海域水体异养细菌的时空分布特征研究

为探讨环境因素对异养细菌丰度的影响,2016年9月至2017年8月通过月度航次调查对北部湾北部海域异养细菌丰度的时空分布特征进行了系统研究。结果表明,调查海区异养细菌丰度介于（2.75~56.86）×105 cell/mL,平均值为（11.01±6.31）×105 cell/mL。各季节细菌丰度从高至低依次为:夏季、春季、冬季、秋季。异养细菌丰度由近岸海域向西南深水区方向逐渐降低,在近岸浅水区垂直分布均匀,在水深大于20 m的海区出现季节性分层现象:表层细菌丰度较高,底层细菌丰度较低。主成分分析显示温度对异养细菌时空分布有重要影响,秋、冬季异养细菌丰度与温度呈显著负相关,在春、夏季呈显著正相关。细菌丰度与盐度呈显著负相关,说明海水盐度变化是细菌时空分布重要影响因素。异养细菌丰度与叶绿素a和溶解氧含量呈显著正相关,表明浮游植物初级生产过程影响了异养细菌的时空分布。在秋、冬和春3季异养细菌丰度与营养盐水平呈显著负相关,二者关系受浮游植物生物量间接影响。异养细菌时空分布差异取决于环境条件的变化,温度、盐度、叶绿素a和溶解氧含量是影响异养细菌丰度分布的主要因素。     

High inorganic phosphate concentration in coral mucus and its utilization by heterotrophic bacteria in a Malaysian coral reef

Inorganic nutrient contents of mucus released by Acropora corals and its utilization by heterotrophic bacteria at several different hour intervals in the coral mucus were investigated at a coral reef in Malaysia. The dissolved inorganic phosphate (DIP) concentration was 135‐fold higher than in the ambient seawater, probably due to inorganic P release from the coral gut cavity. We experimentally confirmed that heterotrophic bacteria rapidly (within 8 h) consumed ca. 80% of the initial concentration of DIP derived from coral mucus. High DIP concentration in coral mucus may enhance heterotrophic bacterial production and associated carbon flow in the microbial loop of reef ecosystems.     

The action of heavy metals on the gametes of the marine mussel, Mytilus edulis (L.)-II. Uptake of copper and zinc and their effect on respiration in the sperm and unfertilized egg

The addition of stock copper and zinc nitrate solutions to filtered seawater (pH 7·91) resulted in a large pH shift which was more pronounced with copper. The pH shift was minimized by increasing the buffering capacity of seawater using 10 mm Tris-Tes pH 7·91. Subsequent experimentation was carried out in both unbuffered and buffered seawater.In unbuffered seawater, both copper and zinc had a pronounced inhibitory effect on Mytilus edulis sperm respiration with 50% inhibition occurring at 0.65 mm (41·3 ppm) copper and 1.0 mm (65·4 ppm) zinc. Egg respiration was also inhibited by copper with 50% inhibition occurring at 0.9 mm (57·2 ppm) whereas zinc inhibited egg respiration by only 30% at 1·5 mM (98·1 ppm).In buffered seawater, both copper and zinc produced an inhibitory effect on sperm respiration. However, with copper the inhibition was much reduced whereas zinc had tthe same inhibitory effect as in unbuffered seawater. In contrast to unbuffered seawater, egg respiration was stimulated by copper but zinc produced a comparable respiratory inhibition. The uptake of both copper and zinc in sperm and egg in buffered seawater increased with increasing metal concentration. Metal ion uptake, when expressed as ng ions μl cell volume^?1, was approximately 3-fold greater in the sperm than in the eggs and in both cases zinc uptake exceeded copper uptake.At a seawater pH of < 7·5, in the absence of copper or zinc, the respiration of both egg and sperm was inhibited. The maximum levels of inhibition at pH 5·4 were 15% and 30% for sperm and egg, respectively.The differing actions of copper on egg respiration in buffered and unbuffered seawater appear to be due to enhanced copper uptake in unbuffered seawater.     

广东沿海香港牡蛎消化道异养菌统计及其耐药性研究

本研究针对高温时期(6月、9月)广东沿海地区的香港牡蛎(Crassostrea hongkongensis)体内异养细菌总数和弧菌总数进行了深入的调查,并由添加单种抗生素(分别是:庆大霉素、呋喃唑酮、利福平、环丙沙星、恩诺沙星、氯霉素、复方新诺明)的培养基中分离得到310个菌株。进一步采用纸片扩散法(kirby-bauer法)针对常见的抗生素对此310个菌株进行药敏测试,了解不同来源菌株的耐药状况。结果表明310个菌株分属48个不同种属,主要是肠杆菌(Enterobacter)、弧菌(Vibrio)、芽孢杆菌(Bacillus)、肺炎克雷伯菌(Klebsiella)、希瓦氏菌(Shewanella)、不动杆菌(Acinetobacter)、假单胞菌(Pseudomonas)、短波单胞菌(Brevundimonas)、发光杆菌(Photobacterium)、黄杆菌(Tenacibaculum)、盐单胞菌(Halomonas)等。在9月份从牡蛎体内分离的异养细菌比6月份分离的异养细菌高出1～2个数量级(除台山外)。6月份从台山地区牡蛎分离的异养细菌数(2.6×10~6～5.8×10~6 cfu/g)最多,高出其他地区1～3个数量级。药敏测试结果显示牡蛎体内异养细菌对20种抗生素普遍存在抗性,尤其对青霉素、卡拉霉素、呋喃唑酮、阿莫西林、克林霉素及万古霉素表现出较高的耐药率。高温时期(6月、9月)分离的异养菌大多数为多重耐药细菌,其比例分别为84.18%和91.72%。本研究将为牡蛎养殖业的疾病控制以及水产养殖中细菌的耐药状况提供重要参考依据。     

Viruses,bacteria, and heterotrophic nanoflagellates in Laptev Sea plankton

The paper considers the concentrations and functional characteristics of viruses, bacteria, and heterotrophic nanoflagellates determined for the first time in the Laptev Sea in August-September, 2014. The abundance of bacteria, viruses, and heterotrophic nanoflagellates varied from 110.1 × 10³ to 828.4 × 10³ cells/mL, from 384.2 × 10³ to 2932.8 × 10³ particles/mL, and from 108 to 651 cells/mL, respectively. The daily bacterioplankton production varied from 4.2 × 10³ to 381.7 × 10³ cells/mL, with an average of 117.6 × 10³ cells/mL. Electron transmission microscopy has for the first time shown that the frequency of visibly infected bacterial cells varied from 0.2 to 2.0% (0.8% on average) of N_B. The average virus-induced mortality of bacteria was 6.3% of bacterioplankton production, with variations ranging from 1.4 to 16.9%. Grazing on bacteria by heterotrophic nanoflagellates contributed more to bacteria mortality than virus-induced bacterial lysis. By grazing on bacteria, heterotrophic nanoflagellates consumed large quantities of viruses located on the surface and inside bacterial cells.     

海洋围隔中异养细菌与环境中氮、磷关系的研究

利用海洋围隔生态系统实验装置,向海水中施加不同浓度的氮和磷,研究海洋异养细菌与海水环境中氮、磷的关系。结果表明,实验开始后海洋异养细菌的数量就迅速增加,并且一直维持在较高水平,第7~8天达到峰值。但在海洋异养细菌数量达到峰值后,海水中氮和磷的浓度有所回升,磷元素促进了海洋异养细菌的快速生长和繁殖,同时海洋异养细菌在一定程度上也利用了无机氮,海洋异养细菌的数量与海水环境中氮和磷的浓度具有较好的正相关性。     

Changes of seawater quality in Ofunto Bay,Iwate, after the 2011 off the Pacific coast of Tohoku Earthquake

Ofunato Bay was a semi-closed area because of the breakwater effect at the entrance; however, the breakwater was destroyed by a massive tsunami generated by the 2011 off the Pacific coast of Tohoku Earthquake. Consequently, the physical environment of Ofunato Bay has been changed significantly, i.e., the modification of the stratified structure of seawater inside the bay and the intermittent intrusion of seawater outside the bay. These alterations of physical environment are considered to have an influence on the chemical and biological environment in Ofunato Bay. To elucidate the influence of the tsunami on the aquatic environment, we measured dissolved nutrients, chlorophyll a and dissolved oxygen concentrations, and heterotrophic bacteria abundance inside and outside of Ofunato Bay from 2012 to 2014, and compared these data with those obtained before the earthquake. As compared with before the earthquake, significant changes after the earthquake were (1) decrease of ammonium and phosphate concentrations, (2) increase of chlorophyll a concentration, (3) increase of dissolved oxygen concentration in the bottom, and (4) decrease of heterotrophic bacteria abundance. The collapse of the breakwater and consequential enhanced water exchange were considered to have brought the decrease of nutrient concentration inside the bay. Furthermore, washout of shellfish mariculture rafts by the tsunami decreased the shellfish biodeposits along with the elution of nutrients by heterotrophic bacteria. Decrease of cultivated shellfish further caused a decline in feeding pressure on phytoplankton and, subsequently, increased the phytoplankton biomass that contributed to the decrease of nutrients inside the bay.     

Distribution of heterotrophic nanoflagellates and their importance as the bacterial consumer in a eutrophic coastal seawater

Seasonal and vertical changes in abundances of bacteria and heterotrophic nanoflagellates (HNF), and HNF grazing on bacteria were investigated in a small eutrophic inlet of Uranouchi-Wan throughout the years. Bacterial densities in the surface water ranged from 1.2 to 11 (average 4.3)×10⁶ cells ml^–1 with a couple of maxima following the algal blooming. Densities of HNF ranged from 0.54 to 73 (average 16.4)×10³ cells ml^–1 in the surface, and showed almost similar fluctuation pattern to that of bacteria with a time lag of about 1 to 2 weeks. Grazing rates of HNF on bacteria obtained by FLB method were 4.78 to 16.9 (average 10.3±SD 4.8) cells HNF^–1h^–1 in the surface layer in summer, and consequent total bacterial consumption rates by HNF fluctuated from 4 to 99×10⁴ cells ml^–1h^–1. In deeper layers, however, as HNF densities and grazing rates on bacteria were low, the grazing pressure of HNF on bacteria was small. Turnover times of bacteria by HNF grazing in the surface layer were calculated as relatively constant values of 40 to 60 h, however, it decreased to as low as 6 to 7 h when the HNF activity was highest. These results indicate that bacteria grew so actively by consuming organic matter in seawater as to compensate high HNF grazing pressure, and that bacteria and HNF in the microbial loop play important roles on the turnover of substrates in coastal ecosystems.     

Interaction between Chlorella vulgaris and bacteria：interference and resource competition

Research of interaction mechanism between Chlorella vulgaris and two bacterial strains(Z-QD08 and Z-QS01)were conducted under laboratory conditions.Growth rates of bacteria and C.vulgaris were tested under co-culture conditions to evaluate the effects of concentrations of C.vulgaris and bacteria on their interactions.To test whether the availability of inorganic nutrients,vitamins and trace metals affects the interactions between C.vulgaris and bacteria,experiments were performed with or without the culture medium filtrate of C.vulgaris or bacteria.The results showed that the growth of C.vulgaris was promoted at low concentrations of bacteria(5×106cells/ml),and expressed a positive correlation with the bacteria density,whereas opposite trend was observed for treatments with high bacteria density(10×106cells/ml and 20×106cells/ml).The growth rate of bacteria decreased with the increasing concentrations of C.vulgaris.The growth of bacteria Z-QD08 was inhibited by C.vulgaris through interference competition,while the mechanism for interaction between bacteria Z-QS01 and C.vulgaris was resource competition.The influence of cell density on the interaction between microalgae and bacteria was also discussed.These experiments confirm some elements of published theory on interactions between heterotrophic bacteria and microalgae and suggest that heterotrophic bacteria play an important role in the development of blooms in natural waters.     

Effects of an Artificial Breakwater on the Distributions of Planktonic Microbial Communities

The summer distributions of planktonic microbial communities (heterotrophic and phtosynthetic bacteria, phtosynthetic and heterotrophic nanoflagellates, ciliate plankton, and microphytoplankton) were compared between inner and outer areas of Lake Sihwa, divided by an artificial breakwater, located on the western coast of Korea, in September 2003. The semienclosed, inner area was characterized by hyposaline surface water (<17 psu), and by low concentrations of dissolved oxygen (avg. 0.4 mg L¹) and high concentrations of inorganic nutrients (nitrogenous nutrients >36 μM, phosphate <4 μM) in the bottom layer. Higher densities of heterotrophic bacteria and nanoflagellates also occurred in the inner area than did in the outer area, while microphytoplankton (mainly diatoms) occurred abundantly in the outer area. A tiny tintinnid ciliate, Tintinnopsis nana, bloomed into more than 10⁶ cells L¹ at the surface layer of the inner area, while its abundance was much lower (10³-10⁴ cells L¹) in the outer area of the breakwater. Ciliate abundance was highly correlated with heterotrophic bacteria (r = 0.886, p < 0.001) and heterotrophic flagellates (r = 0.962, p < 0.001), indicating that rich food availability may have led to theT. nana bloom. These results suggest that the breakwater causes the eutrophic environment in artificial lakes with limited flushing of enriched water and develops into abundant bacteria, nanoflagellates, and ciliates.     

Organic and inorganic speciation of copper in the Irish Sea

The metal complexing ability of surface water of the Irish Sea has been measured by the MnO₂ adsorption method. In all samples strong copper-chelating compounds are present at concentrations of 60–150 nM, with conditional stability constants (log values) of 10.0–10.4. The concentrations of Cu, Pb and Cd in the samples are 16–39 nM, 1–7 nM and 0.1–2 nM, respectively; much less than the ligand concentrations. The organic compounds form complexes with 94–98% of dissolved copper, and therefore constitute the major form of copper in surface water of the Irish Sea. Recalculation of speciation of the inorganic fraction of copper in seawater reveals that the major complex ion is that of CuCO₃⁰ (60%), followed by CuOH⁺ (16%) and Cu(OH)₂⁰ (16%). Complexes with borate ions form a small and rather insignificant fraction of 1%.     

Filter-feeder macroinvertebrates as key players in culturable bacteria biodiversity control: a case of study with Sabella spallanzanii (Polychaeta: Sabellidae)

The present study investigates the effect of the filtering activity of Sabella spallanzanii on the culturable heterotrophic bacterial community through the comparison of the bacterial diversity in transplanted polychaetes and the surrounding seawater. For isolation of culturable heterotrophic bacteria, seawater samples as well as polychaete homogenates were plated in triplicates onto Bacto Marine Agar 2216 (Difco). All the colonies grown were isolated, subcultured and identified by several morphological, biochemical and cultural methods. Some bacterial genera showed higher average abundances in polychaetes than in seawater (i.e. Lucibacterium and Photobacterium). Aeromonas represented a conspicuous component of the bacterial community both in S. spallanzanii and seawater. The presence of Cytophaga and Pseudomonas was also relevant in the examined seawater samples. The selective concentrations of some bacterial genera inside S. spallanzanii either by grazing on bacteria or their capability as bacterial reservoirs, provides evidence for the role of macrobenthic invertebrates as key determinants for microbial diversity.     

硫酸盐还原菌对热镀锌钢材氢渗透行为的影响

采用Devanathan-Stachurski 双面电解池检测氢渗透电流技术和扫描电镜分析, 研究了热镀锌钢材在灭菌海水、灭菌培养基和接种了硫酸盐还原菌(SRB)的培养基等3 种介质中的氢渗透行为。氢渗透电流检测结果表明, 培养基的部分组分对热镀锌钢材的氢渗透行为有促进作用, 试样在灭菌培养基中的氢渗透电流密度的平均值比在灭菌海水中提高了约6 倍。尽管活性SRB 代谢产生的S^2?和HS^?能够促进热镀锌钢材的氢渗透行为, 但是, 由SRB 及其代谢产物和它们所黏附的腐蚀产物所形成的致密微生物膜减少了氢的析出和试样对氢的吸收量, 导致热镀锌钢材氢渗透行为最终被抑制, 因此, 试样在接菌培养基中的氢渗透电流密度的平均值比其在灭菌培养基中降低77%。扫描电镜分析表明, 热镀锌钢材在灭菌海水中能够形成腐蚀产物膜, 而暴露于灭菌培养基中的试样表面未形成明显的腐蚀产物膜, 但在接菌培养基中试样表面能形成黏附了腐蚀产物的致密微生物膜的附着, 表明热镀锌钢材表面的微生物膜与其氢渗透行为之间存在明显的相关性。     

The importance of dissolved organic compounds in the accumulation of copper by the american oyster,crassostrea virginica

The influence of various dissolved organic compounds upon copper accumulation by the American oyster, Crassostrea virginica was examined. Oysters were exposed to a range of copper concentrations (^64Cu) in the presence of filtered estuarine water (FEW), UV-photooxidized FEW and FEW amended with the additions of natural dissolved organic compounds—chitin and cellular orgaanic compounds (derived from the diatom, Thalassiosira pseudonana). Copper accumulation rates were significantly greater in the UV-treated medium and decreased with the addition of dissolved organics. When normalized on a per weight DOC basis, the reductions in copper accumulation rates were greater in the presence of chitin than cellular organic compounds. The results suggest that natural dissolved organics differ markedly with respect to their influence upon copper bioavailability.     

乳山湾的污染与异养微生物的调查分析

于1985年5—10月定期采取了乳山湾内和岸边养虾池的水样及底泥进行了异养微生物的分析。菌数的平均值池内高于湾内,其最高值和水中COD的最高值同时出现在养虾旺季的8月份。在湾泥和池泥中的硫酸盐还原菌数均高达10~6个/克以上,与同期内硫化物的最高含量(326mgS/kg)相一致。并发现病原性弧菌也广泛存生。异养菌种群的组成,假单胞杆菌占有最大的比值,反映出该水域为污染类型。上述结果表明该湾的水质条件已远超出国家渔业水质标准,呈现高度的有机物污染状态,其污染源与湾边周围开展大面积的养虾有关。     

Significance of the Virus-Rich 2–200 nm Size Fraction of Seawater for Heterotrophic Flagellates: I. Impact on Growth

Abstract. The effect of artificially changing the concentration of naturally occurring free virus-like particles (VLPs) on growth of marine heterotrophic flagellates was tested in batch cultures using ultrafiltration technology. This manipulation influenced the course of flagellate growth markedly. During 1 week of incubation the growth of 4 tested flagellate strains ( Oxyrrhis marina, Paraphysomonas imperforata, Petalomonas cantuscygni, Pteridomonas danica ) was strongly favoured after increasing the VLP concentration. Bacteria, however, were repressed in these treatments beyond 50 h. In cultures with natural seawater microbiota, we both reduced and enriched the concentration of VLPs. In these cultures, reduction of material in the virus-rich 2–200 nm size fraction led to a strong positive growth response of heterotrophic flagellates. In VLP-enriched treatments of natural seawater microbiota a tendency toward growth stimulation was also found, although this was not significant. Enrichment with VLPs caused no recognizable mortality either in cultured flagellate strains or in naturally occurring flagellate communities. However, it is suggested that a highly bioactive component must be present in the virus-rich 2–200 nm size fraction. Virus-like particles are discussed as possible candidates influencing heterotrophic flagellate community successions.