一株自太湖微囊藻上分离到的细菌的生长及磷代谢

磷是引起湖泊水华爆发的关键元素,微囊藻（Ｍｉｃｒｏｃｙｓｔｉｓ）是太湖水华的主要藻种,为了研究磷在湖泊水体低级食物链（细菌、浮游动植物等）中的代谢,以一株自太湖微囊藻上分离的假单胞菌（Ｐｓｅｕｄｏｍｏｎａｓ ｓｐ．）Ｘ菌株为试验菌,研究了磷形态及生长因子对其生长的影响,结果表明无机磷浓度对Ｘ菌生长的影响不大,而ＡＴＰ对Ｘ菌的生长有抑制作用;在含有无机磷和有机磷的培养基中,Ｘ菌优先利用无机磷盐,Ｘ菌     

梭菌对含镁方解石形态的控制及其可能机理

在 Mg/Ca 摩尔比为 4∶1 的 Lagoa Vermelha 培养基中对一株分离自青海湖底沉积物的梭菌 SN-1（Clostridium sp.）进行了为期 55 d 的碳酸盐矿物培养实验,同时还完成了一组无菌对照实验。利用扫描电子显微镜对沉淀物进行了系统的观察,用 X- 射线衍射仪对沉淀物的矿物成分进行了测定。结果表明：（1）SN-1 可以促进特殊形态含镁方解石的形成,而无菌对照实验产物中仅见不规则状的碳酸盐矿物;（2）特殊形态的含镁方解石可能是在细菌表面成核和生长的结果,它们的演化趋势是（杆状）→哑铃形→花菜状→球形。作者认为这是因为梭菌两端的带负电基团比菌体中间丰富,易聚集更多的 Ca²⁺和 Mg²⁺,Ca²⁺和 Mg²⁺离子作为“阳离子桥”吸引 CO32-,其结果是两端的晶体生长相对较快、中间生长相对较慢,进而形成哑铃形含镁方解石;“哑铃”继续生长,其两端会长成两个“花菜”或半球;若两个半球相接并闭合则发展为球状矿物。     

福建晋江深沪湾海底古森林群落类型的初步研究

 深沪湾海底古森林座落在北纬24°37～40',东经118°38'～40',福建省晋江市深沪湾潮间带中下部。在1986年该古森林被发现时仅有树桩7棵,其中4棵样品被鉴定为松科(Pinaceae)植物,与现代油杉属(Keteleeria carr.)的木材结构相似。     

Influence of the concentration ratio of nitrogen to phosphorus on the growth and interspecies competition of two red tide algae

The growth and interspecies competition of two red tide algal species Thalassiosira pseudonana Hasle et Heimdal and Gymnodinium sp.were studied under different concentration ratios of nitrogen to phosphorus,and the algal batch culture experiments were conducted.The physiological and biochemical indexes were measured periodically,including the maximum comparing growth rate,relative growth rate,average double time and chlorophyll a concentration.The results showed that when the concentration ratio of nitrogen to phosphorus was 16:1,the maximum comparing growth rate,relative growth rate and chlorophyll a concentration of Thalassiosira pseudonana all reached the highest,and average double time was the shortest.This implied that the optimal concentration ratio of nitrogen to phosphorus of Thalassiosira pseudonana is 16:1.When the concentration ratio of nitrogen to phosphorus was 6:1,the maximum comparing growth rate,relative growth rate and the chlorophyll a concentration of Gymnodinium sp.reached the highest,and average double time was the shortest,so the optimal concentration ratio of nitrogen to phosphorus of Gymnodinium sp.is 6:1.From the growth curves as indicated both in the cell density and the chlorophyll a concentration,it is suggested that the influence of concentration ratio of nitrogen to phosphorus on the chlorophyll a concentration and the cell density are almost the same.Different concentration ratios of nitrogen to phosphorus had weak influence on community succession and the competition between the two algae.Gymnodinium sp.may use the phosphorus in vivo for growth,so it is important to pay attention to the concealment of phosphorus,in order to avoid the outbreak of red tide.On the basis of the importance of nitrogen and phosphorus and the ratio of their concentration,the possible outbreak mechanism of red tide of the two algae was also discussed.     

小球藻EC04产胞内多糖条件优化及抗氧化活性研究

小球藻胞内多糖等活性物质具有多种重要生物活性和生理功能。为提高小球藻EC04胞内多糖的产率, 采用单因素实验和L₉(3 ⁴)正交实验优化对其培养条件进行优化。在暗光比12∶12、温度24±1℃和2000Lux光照条件下, EC04产胞内多糖的最佳条件为: MgSO₄·7H₂O浓度112.5mg·L ^-1, K₂HPO₄浓度60mg·L ^-1, NaNO₃浓度1.2g·L ^-1, 维生素B₁浓度0.5mg·L ^-1, 维生素B₁₂浓度0.1μg·L ^-1。在此条件下, EC04产糖率为271.74mg·g ^-1, 细胞密度为48.027×10 ⁶cells·mL ^-1, 与基础培养基相比分别提高了97.49%和34.91%。添加VB₁、VB₁₂等也在不同程度上影响小球藻胞内多糖产率。对所提取胞内多糖进行抗氧化活性初探, 结果表明其具有一定的自由基的清除能力, 对DPPH·(1-二苯基-2-三硝基苯肼)和·OH(羟自由基)的最大清除率分别达到了82.32%和64.27%。     

4 种经济海藻脂肪酸组成分析

采用改进的Bligh-Dyer法提取脂溶性成分,气相色谱-质谱联用法(GC-MS)进行分离和鉴定,C19:0内标确定总脂及各组分含量,研究了鼠尾藻(Sargassum thunbergii)、浒苔(Enteromorpha prolifera)、龙须菜(Gracilaria lemaneiformis)和红毛菜(Bangia sp.)4种经济海藻的脂肪酸组成及含量。结果表明,4种海藻都检测出C14-C22脂肪酸,总脂含量在12～19 mg/g之间,不饱和脂肪酸为主要组成成分,含量均超过60%。不饱和脂肪酸中以多不饱和脂肪酸(PUFAs)为主,富含n-3和n-6系列PUFAs,n-6与n-3系列PUFAs之比均低于2。比较4种海藻脂肪酸组成特点表明,鼠尾藻以C16、C18和C20为主要组成成分,具褐藻类脂肪酸组成特征;浒苔以C16和C18为主要组成成分,具绿藻类脂肪酸组成特征;龙须菜和红毛菜以C16和C20类脂肪酸为主,具典型红藻类脂肪酸组成特征,同时二者又有不同之处,分别显示真红藻与原始红藻脂肪酸组成的特点。     

One new free-living marine nematode species of genus Cephalanticoma from the South China Sea

One new species of free-living marine nematode Cephalanticoma brevicaudata sp. nov. from the South China Sea is described. Cephalanticoma brevicaudata sp. nov. is characterized by spindle body with relatively short tail; head with cephalic capsule; three teeth at anterior of pharynx; excretory pore opens posterior to cervical setae; three cervical setae per file; spicules arcuate, cephalate and ventrally bent proximally, and blunt distally, 1.8 a.b.d. long, without ventral ala; gubernaculun slender, simple rod, without apophyses; tubular supplement 34 μm long, 2.3 a.b.d. in front of cloaca.     

Synthesis of three-dimensional agaric-like biomorphic TiO2 by a facile method with Coscinodiscus sp. frustule

The paper aims to expand the application of natural marine algae.Marine diatoms,which have intricate frustule structures,can serve as bio-template for preparing three-dimensional materials.A simple and effective approach to synthesize the corrugated agaric-like biomorphic TiO 2 templated with frustule of Coscinodiscus sp.is reported.In the sol-gel preparation process,the titania-coating on the frustule is prepared through the deposition and condensation with the aid of acetylacetone(acac) as a controlling agent to make the precursor Ti(BuO) 4 hydrolyze slowly.The as-prepared titania-coated frustule and biomorphic TiO 2 is characterized by scanning electron microscopy(SEM) attached with energy dispersive X-ray spectrometer(EMAX) and X-ray diffraction(XRD).The microstructure of the corresponding titania nanoparticles appears to be sphere with the diameters distributed around 10 20 nm.The templating process is repeated for three cycles.Subsequently,the three-dimensional freestanding corrugated agaric-like biomorphic TiO 2 structure is obtained by a selective removal in the NaOH solution.As far as we known,the 3D freestanding corrugated agaric-like biomorphic TiO 2 with greatly increased surface area is obtained for the first time.     

中国黄海海域繁茂膜海绵生长生殖周期的组织学特征

利用组织学和超微结构方法,对大连黄海海域的繁茂膜海绵(Hymeniacidonsp.)在自然海域的生长和生殖过程的组织学特征进行了近2a的观察。结果表明:繁茂膜海绵的生长呈现周期性变化,分为4个阶段:复苏期(3～5月)、生长旺盛期(6～8月)、衰退期(9～11月)和冬眠期(12月—次年2月)。繁茂膜海绵可以通过有性生殖进行繁殖,显著生殖期为8～10月,期间可以观察到卵细胞、精细胞囊、胚胎和幼虫。研究结果为深入研究繁茂膜海绵自然生长生殖特点,进而实现海绵组织块的继代培养和人工育种提供实验依据。     

Methane levels in shallow subtropical lake sediments: Dependence on the trophic status of the lake and allochthonous input

The vertical sediment profiles (10 cm) of the margins of three shallow subtropical lakes (Rio Grande, Brazil) with different trophic states and surrounding areas were evaluated to identify the effects of the allochthonous input on the methane concentration in the sediment. Sediment cores were collected to quantify the organic matter content (OM) and total carbon (TC), total nitrogen (TN), total phosphorous (TP) and methane (CH₄) concentrations.The three lakes were distinguished according to the trophic status and classified as oligotrophic, dystrophic and eutrophic. The natural characteristics of the dystrophic and eutrophic lakes have been changed due to the allochthonous input of leaves and twigs (Eucalyptus sp.) and the excreta of birds, respectively. In the eutrophic lake, the allochthonous input contributed to high autochthonous production. The highest values of OM, TC, TN and TP were found in the superficial sediments of the dystrophic and eutrophic lakes. The accumulation of allochthonous organic matter in the littoral zone promoted changes in the vertical sediment profiles and contributed to increases in the CH₄ concentrations in the sediment.