海洋微生物来源的岩藻多糖降解酶

近年来研究发现,岩藻多糖及其降解产物具有多种重要的生物学活性,对岩藻多糖降解酶的关注日益增多。本文概述了海洋微生物来源的岩藻多糖降解酶的发现、活性检测方法、性质、应用等方面的研究进展。同时展望了现代组学及结构生物学技术快速发展对海洋微生物来源的新型岩藻多糖降解酶研究的推动作用。     

Studying marine microorganisms from space

Microorganisms are but a few micrometers in diameter and are not visible to the naked eye. Yet, the large numbers of microorganisms present in the oceans and the global impact of their activities make it possible to observe them from space. Here a few examples of how microorganisms can be studied from satellites are presented. The first case is the best known: the main pigment used in photosynthesis (chlorophyll a) can be determined from satellites. These kinds of studies have contributed a tremendous amount of understanding about the distribution and dynamics of primary production in the oceans. Two other examples will concern analysis of heterotrophic prokaryotic production and estimates of dimethyl sulfide (DMS) concentration and flux to the atmosphere. These three processes are of fundamental importance for the functioning of the biosphere. Marine microbes carry out about half of the total primary production in the planet. A substantial fraction of the respiration in the oceans is due to the activity of heterotrophic prokaryotes. Finally, the flux of DMS to the atmosphere is believed to constitute one of the mechanisms by which the biota can regulate climate. The global implications of microbial processes in the oceans can only be addressed with the help of satellites. Electronic Publication     

Chitinases from uncultured marine microorganisms.

Our understanding of the degradation of organic matter will benefit from a greater appreciation for the genes encoding enzymes involved in the hydrolysis of biopolymers such as chitin, one of the most abundant polymers in nature. To isolate representative and abundant chitinase genes from uncultivated marine bacteria, we constructed libraries of genomic DNA isolated from coastal and estuarine waters. The libraries were screened for genes encoding proteins that hydrolyze a fluorogenic analogue of chitin, 4-methylumbelliferyl beta-D-N,N'-diacetylchitobioside (MUF-diNAG). The abundance of clones capable of MUF-diNAG hydrolysis was higher in the library constructed with DNA from the estuary than in that constructed with DNA from coastal waters, although the abundance of positive clones was also dependent on the method used to screen the library. Plaque assays revealed nine MUF-diNAG-positive clones of 75,000 screened for the estuarine sample and two clones of 750,000 for the coastal sample. A microtiter plate assay revealed approximately 1 positive clone for every 500 clones screened in the coastal library. The number of clones detected with the plaque assay was consistent with estimates of the portion of culturable bacteria that degrade chitin. Our results suggest that culture-dependent methods do not greatly underestimate the portion of marine bacterial communities capable of chitin degradation.     

海洋微生物生物活性物质研究

海洋微生物以其分类的多样性和遗传背景的特征而具有产生新型生物活性物质的巨大潜力,本文对海洋微生物产生的生物活性物质的研究进展进行了综述,从报道的研究结果看,占海洋微生物主导地位的海洋细菌产生的活性物质种类最为丰富;海洋真菌和海洋放射线菌虽非海洋微生物中的主要菌群,但其产生新型生物活性物质的潜能不可低估。此外,目前研究主要局限于那些在常规条件下易于培养的微生物类群,今后的之一是对于非可培养海洋微生物产生的生物活性物质的探索,我国应充分利用国内海洋微生物资源优势加强这一领域的研究。     

Biosurfactants,bioemulsifiers and exopolysaccharides from marine microorganisms

Marine biosphere offers wealthy flora and fauna, which represents a vast natural resource of imperative functional commercial grade products. Among the various bioactive compounds, biosurfactant (BS)/bioemulsifiers (BE) are attracting major interest and attention due to their structural and functional diversity. The versatile properties of surface active molecules find numerous applications in various industries. Marine microorganisms such as Acinetobacter, Arthrobacter, Pseudomonas, Halomonas, Myroides, Corynebacteria, Bacillus, Alteromonas sp. have been studied for production of BS/BE and exopolysaccharides (EPS). Due to the enormity of marine biosphere, most of the marine microbial world remains unexplored. The discovery of potent BS/BE producing marine microorganism would enhance the use of environmental biodegradable surface active molecule and hopefully reduce total dependence or number of new application oriented towards the chemical synthetic surfactant industry. Our present review gives comprehensive information on BS/BE which has been reported to be produced by marine microorganisms and their possible potential future applications.     

海洋动物来源微生物的共培养研究进展

近年来,由于一些新疾病的发生和细菌耐药性的出现,微生物来源次级代谢产物的筛选重复率越来越高,微生物一些代谢基因在现有实验室条件下无法表达,所以需要发现新的微生物资源,同时找到激活微生物代谢产物基因的方法.海洋动物体内蕴含着大量的共附生微生物资源,可以产生很多具有生物活性的化合物,是潜在的药用资源.本文综述了近年来海洋动...     

Antibiotic activity of marine microorganisms

Summary 1. 41 sea water samples vollected between 18°00'N – 72°00'E and 18°52'N – 72°85'E were screened for marine bacteria possessing antagonistic properties againstStaphylococcus aureus andSalmonella typhosa.2. Of 60 cultures elaborating antibiotic principles, a majority (45) were aerobic spore forming bacilli; the rest included gram-positive cocci (11), gram-negative bacilli (2) and streptomycetes (2).3. The majority of the isolates showed higher activity against the gram-negative test organism.4. Eleven different media were used to observe the effect of nutrients on the production of antibiotic substances.

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Antibiotische Aktivität mariner Mikroorganismen

Kurzfassung Aus 41 Seewasserproben verschiedener Herkunft wurden 60 Stämme mariner Bakterien mit antagonistischen Eigenschaften gegenüberStaphylococcus aureus undSalmonella typhosa isoliert. Die Wirkung verschiedener Nährstoffe auf die Produktion der antimikrobiellen Substanzen wurde untersucht.

     

Bromo- and iodo-containing alkaloids from marine microorganisms and sponges

The taxonomic distribution, structure, and biological activity of halogenated alkaloids isolated from marine microorganisms and sponges are reviewed. The structures of nearly 140 natural bromo- and iodo-containing alkaloids are shown.     

A comparative study of specificity of fucoidanases from marine microorganisms and invertebrates

Specificities of actions of fucoidanases from the marine microorganism Pseudoalteromonas citrea KMM 3296 and the marine mollusk Littorina kurila were studied. The enzymes possess similar specificities and catalyze the cleavage of accessible α-(1→3)-fucoside bonds in fucoidans with highly sulfated α-(1→4; 1→3)-L-fucooligosaccharides. A high degree of sulfation of the fucose residues in fucoidans makes α-(1→3)-L-fucoside bonds inaccessible for the action of the studied enzymes. The maximum degree of cleavage of fucoidan was achieved by the fucoidanase from the marine bacterium Pseudoalteromonas citrea KMM 3296.     

Isolation of porphyran-degrading marine microorganisms from the surface of red alga, Porphyra yezoensis

Marine microorganisms degrading porphyran (POR) were found on the surface of thalli of Porphyra yezoensis. Fifteen crude microorganism groups softened and liquefied the surface of agar-rich plate medium. Among these, 11 microorganism groups degraded porphyran that consisted of sulfated polysaccharide in Porphyra yezoensis. Following isolation, 7 POR-degradable microorganisms were isolated from the 11 POR-degradable microorganism groups.     

Expression of a metagenome-derived fumarate reductase from marine microorganisms and its characterization

A potential novel fumarate reductase gene designated frd1A was isolated by screening a marine metagenomic library through a sequence-based strategy. Sequence analyses indicated that Frd1A and other putative fumarate reductases were closely related. The putative fumarate reductase gene was subcloned into a pETBlue-2 vector and expressed in Escherichia coli Tuner(DE3)pLac? cells. The recombinant protein was purified to homogeneity. Functional characterization by high-performance liquid chromatography demonstrated that the recombinant Frd1A protein could catalyze the hydrogenation of fumarate to succinate acid. The Frd1A protein displayed an optimal activity at pH 7.0 and 28 °C, which could be stimulated by adding metal ions such as Zn²⁺ and Mg²⁺. The Frd1A enzyme showed a comparable affinity and catalytic efficiency under optimal reaction conditions: k _m?=0.227 mmol/L, v _max= 29.9 U/mg, and k _cat/k _m=5.44?×?10⁴ per mol/s. The identification of Frd1A protein underscores the potential of marine metagenome screening for novel biomolecules.     

Antibiotic activity of marine microorganisms: the antibacterial spectrum

Summary 1. The antibacterial spectrum of sixty marine bacteria was determined using twenty test organisms.2. Gram-positive organisms were in general found to be more susceptible to antibiotics produced by marine bacteria than the gram-negative forms.3. The production of antibacterial substances by marine bacteria may be one of the factors responsible for the rapid reduction in number of adventitious organisms entering the marine environment.

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Antibiotische Aktivität mariner Mikroorganismen: Das antibakterielle Spektrum

Kurzfassung Das antibakterielle Spektrum von sechzig Antibiotika produzierenden Mikroorganismen mariner Herkunft wurde bestimmt. Zwanzig verschiedene Bakterienarten dienten als Testorganismen; von ihnen waren fünfzehn gramnegativ, vier grampositiv und eine Art säurefest.

     

Metagenomic analysis reveals diverse polyketide synthase gene clusters in microorganisms associated with the marine sponge Discodermia dissoluta

Sponge-associated bacteria are thought to produce many novel bioactive compounds, including polyketides. PCR amplification of ketosynthase domains of type I modular polyketide synthases (PKS) from the microbial community of the marine sponge Discodermia dissoluta revealed great diversity and a novel group of sponge-specific PKS ketosynthase domains. Metagenomic libraries totaling more than four gigabases of bacterial genomes associated with this sponge were screened for type I modular PKS gene clusters. More than 90% of the clones in total sponge DNA libraries represented bacterial DNA inserts, and 0.7% harbored PKS genes. The majority of the PKS hybridizing clones carried small PKS clusters of one to three modules, although some clones encoded large multimodular PKSs (more than five modules). The most abundant large modular PKS appeared to be encoded by a bacterial symbiont that made up < 1% of the sponge community. Sequencing of this PKS revealed 14 modules that, if expressed and active, is predicted to produce a multimethyl-branched fatty acid reminiscent of mycobacterial lipid components. Metagenomic libraries made from fractions enriched for unicellular or filamentous bacteria differed significantly, with the latter containing numerous nonribosomal peptide synthetase (NRPS) and mixed NRPS-PKS gene clusters. The filamentous bacterial community of D. dissoluta consists mainly of Entotheonella spp., an unculturable sponge-specific taxon previously implicated in the biosynthesis of bioactive peptides.     

海洋环境下腐蚀微生物研究进展北大核心

海洋环境的复杂多变性使海洋腐蚀成为一个日益严重的全球性问题。海洋腐蚀在造成巨大经济损失的同时,还带来了严重的环境污染以及人员安全问题,使其成为海洋经济发展中必须要解决的关键问题。据统计海洋环境中20%的腐蚀由微生物引起,腐蚀微生物(microbiologically influenced corrosion,MIC)以生物膜的形式存在于金属表面,其主要包括细菌、古菌、真菌及藻类等。基于对以往研究的综述,本文总结了这4类海洋微生物的研究进展,阐述了海洋腐蚀环境中腐蚀微生物的种类、群落组成影响因素及其作用机理等内容;同时,文中概述了微生物对金属材料促进腐蚀或抑制腐蚀的影响因素及其作用机制,并归纳了当前海洋环境中微生物腐蚀的防治方法;最后,本研究对海洋环境下微生物腐蚀研究及防治的发展趋势进行了论述,以期为腐蚀机制的研究与防腐工作的实施提供参考。     

海洋微生物多样性的研究进展

海洋微生物多样性（marine microorganisms diversity)是指所有海洋微生物种类、种内遗传变异和它们的生存环境的总称。本文介绍了海洋微生物多样性方面的研究和利用进展,包括研究微生物多样性方法的改进,有价值的海洋微生物功能性产品的开发;关于海洋微生物抗肿瘤、抗病毒药物的研究等。