盐度和pH对底栖硅藻胞外多聚物的影响

研究了盐度和pH值对底栖硅藻新月筒柱藻(Cylindrotheca closterium(Ehr.)Reimannet Lewin)增殖、蛋白质含量和胞外多聚物(Extracellular Polymeric Substances,EPS)的影响.结果表明新月筒柱藻最适生长的盐度和pH值分别是15和8,属半咸水性生活.高盐度(>15)和低pH值(相似文献   

中国极地微生物学调查研究进展

中国自行组建的极地微生物学调研起始于上世纪80年代初,迄今20余年来,中国极地微生物学研究取得了丰硕的成果,调查范围涉及南北极,包括南极长城站、中山站及其附近区域土壤、空气、水体和南大洋水域,及从中取得的生命和非生命材料、白令海和楚科奇海、波弗特海、加拿大海盆等北冰洋海区,及青藏高原等等。对极地微生物的种群、含量、多样性、生长特征、生理生化特性、系统发育等作了广泛而有深度的研究分析,并就其中的一些菌株的活性物质开发利用进行了有意义的探索。最后对今后中国极地微生物学的研究提出了一些建议。     

Inhibition of spore germination of Ulva pertusa by the marine bacterium Pseudoalteromonas haloplanktis CI4

The e?ect of the bacterial strain CI4 on the germination of spores from the green alga Ulva pertusa was assayed and it was found that the bacterial bioˉlm and cell-free supernatant strongly inhibited spore germination. In attempts to deˉne the chemical nature of the antifouling substance in the supernatant of CI4, the culture supernatants were tested for activity after heat treatment, enzy- matic treatments, size fractionation, and separation into aqueous and organic fractions. Results suggest that this bacterium produces an extracellular component with speciˉc activity toward algal spores that was heat-sensitive and between 3 and 10 kDa in molecular size. The exposure of the organic phase fraction to spores showed inhibitive e?ect on spore germination. Pronase and car- boxypeptidase y did not signiˉcantly a?ect the activity of inhibitory component, suggesting that the component was not a protein or a peptide. The bacterium CI4 was identiˉed as Pseudoalteromonas haloplanktis based on the phenotypic characters and 16S rRNA gene analysis.     

龙须菜对3种赤潮微藻生长的影响

在共生条件下,研究了鲜龙须菜对前沟藻、米氏凯伦藻和塔玛亚历山大藻等3种赤潮微藻生长的影响.在此基础上,以龙须菜培养水过滤液和龙须菜水溶性抽提液为实验用液,分析它们对上述3种赤潮微藻的抑制作用.最后,采用甲醇浸泡龙须菜干粉末,研究了其甲醇提取物对3种赤潮微藻生长的影响.结果表明,当鲜龙须菜浓度≥32 g·L-1时,其能显...     

海洋微生物活性物质的研究进展

海洋微生物由于其特殊的生存环境,往往能产生结构新颖、功能多样的活性物质,海洋微生物作为活性物质的新来源,正日益受到人们的关注。综述了近几年海洋微生物产生的抗肿瘤、抗心血管病、免疫调节剂、抗生素等生物活性物质的开发利用现状及相关的研究技术和方法,展示出海洋微生物活性物质巨大的开发利用前景。     

Dissolved inorganic nutrients and organic substrates in the River Warnow (North-Eastern Germany) – Utilisation by bacterioplankton

After 1990, external loads of Central European rivers with inorganic nutrients (nitrogen and phosphorus) and organic material were reduced because of changed environmental laws. However, in the eutrophic lowland River Warnow, North-Eastern Germany, nitrate concentrations remained high with 35–185 μmol l⁻¹ without a significant decrease since 1992. In contrast, phosphate concentrations, varying between 0.3 and 5.2 μmol l⁻¹ during the growth season 2002, decreased significantly over the years. However, its concentrations still exceeded 1 μmol l⁻¹ regularly in the growth seasons. This load led to a substantial accumulation of organic matter additional to high terrestrial inputs. Despite the high organic load, the remineralising bacteria were mainly inactive in River Warnow. Therefore, the composition of the dissolved organic material, especially its bioavailability, were investigated during the growth season 2002 and discussed with other potential controlling factors. River Warnow carried a high load of dissolved organic carbon (14 mg l⁻¹), especially of humic substances (5.5 mg C l⁻¹). Bacterial abundance (12×10⁶ ml⁻¹) as well as production (1.7 μg C l⁻¹ h⁻¹) depended on temperature. During late spring and summer at constantly higher temperatures, bacterial production correlated positively to readily utilisable substrates and to humic compounds. Thus, the bacterial community in River Warnow may be well adapted or contain enough species using the available amino acids and carbohydrates as well as humic matter compounds. However, calculated from protozoan biomass, grazing may control bacterial biomass and perhaps community composition profoundly, what lead to the low percentages of active bacteria.     

Jurassic septarian concretions from NW Scotland record interdependent bacterial, physical and chemical processes of marine mudrock diagenesis

Septarian concretions in the Staffin Shales Formation (Kimmeridgian, Isle of Skye) allow controls on concretion rheology and septarian cracking to be investigated. Stratabound concretions consist of anhedral ferroan calcite microspar enclosing clay and minor pyrite. Intergranular volumes range from 77% to 88%, and calcite δ¹³C and δ¹⁸O values in most concretion bodies range from ?10·0‰ to ?17·3‰ and +0·3‰ to ?0·6‰ respectively, consistent with rapid and pervasive cementation in marine pore fluids. Septarian rupture occurred during incipient cementation, with a sediment volume reduction of up to 43%. Crack‐lining brown fibrous calcite records pore fluid re‐oxygenation during a depositional hiatus, followed by increasing Fe content and δ¹³C related to bacterial methanogenesis. Brown colouration results from an included gel‐like polar organic fraction that probably represents bacterially degraded biomass. A new hypothesis for concretion growth and septarian cracking argues that quasi‐rigid ‘proto‐concretions’ formed via binding of flocculated clays by bacterial extracellular polysaccharide substances (EPS). This provided rheological and chemical conditions for tensional failure, subcritical crack growth, volume contraction, calcite nucleation, and incorporation of degraded products into crack‐lining cements. Bacterial decay of EPS and syneresis of host muds provided internal stresses to initiate rupture at shallow burial. Development of septarian (shrinkage) cracks in muds is envisaged to require pervasive in situ bacterial colonization, and to depend on rates of carbonate precipitation versus EPS degradation and syneresis. Subsequent modification of septarian concretions included envelopment by siderite and calcite microspar, hydraulic fracturing associated with Cretaceous shallow burial or Palaeogene uplift; and cementation by strongly ferroan, yellow sparry calcite that records meteoric water invasion of the host mudrocks. An abundance of fatty acids in these spars indicates aqueous transport of organic breakdown products, and δ¹³C data suggest a predominantly methanogenic bicarbonate source. However, the wide δ¹⁸O range for petrographically identical cement (?1·3‰ to ?15·6‰) is difficult to explain.     

海洋真菌药用活性物质研究进展

海洋真菌由于其资源优势和新颖的次生代谢产物,成为海洋天然活性物质的研究热点。按从抗肿瘤、抗菌、酶抑制剂、拮抗剂等几个方面对海洋真菌产生的活性物质的国内外研究情况进行了综述。     

6-苄氨基嘌呤、 2,4-二氯笨氧乙酸对微绿球藻生长与代谢的影响

研究了不同浓度的植物生长物质 ,即 6 苄氨基嘌呤 (6 BA)、2 ,4 二氯笨氧乙酸 (2 ,4 D)对微绿球藻Nannochlorisoculata的生长和代谢影响 ,结果表明 :6 BA和 2 ,4 D在 0 1～ 1 0mg·L 1的实验浓度范围内 ,对微绿球藻的生长、干重、叶绿素a含量、光合作用强度和呼吸作用强度都有一定的促进作用 ,可作为微绿球藻的生长调节剂。6 BA的最佳质量浓度为 0 5mg·L 1;2 ,4 D的最佳质量浓度为 4 0mg·L 1。