深海微生物高压适应与生物地球化学循环

深海是典型的高压环境,嗜压微生物是深海生态系统中的重要类群.随着深海采样技术的发展及高压微生物特殊培养设备的开发,已从深海环境中分离到一系列嗜压微生物,包括一些常压环境不能生长的严格嗜压菌.对这些嗜压菌的研究,不仅对微生物适应极端高压环境的机制有一定了解,而且发现了一些特殊的代谢产物.研究微生物高压嗜压机理,还有助于探索地球生命的温度压力极限及生命起源和演化等科学问题.从深海嗜压微生物多样性、深海微生物高压环境适应机理及深海微生物在生物地球化学循环中的作用等方面对嗜压微生物的研究进展进行综述.     

深海微生物多样性

海洋面积约占地球总面积的70％,平均深度3,800 m,海底平均压力38 MPa,海水以下更是包含有物理化学性质迥异的多种地质结构,例如海洋沉积物、洋壳、热液口以及冷泉等.这些性质迥异的地质结构环境造就了丰富的生物多样性,构成了地球上最大的微生物生态系统.深海海水中最主要的微生物类群是α-,γ-变形菌(Alpha-&Gammaproteobacteria),以及海洋古菌群I(Marine Group I).深海沉积物中微生物含量与有机物含量和距离大陆板块的距离相关,以异养微生物为主.深海冷泉区富集了厌氧甲烷氧化古菌ANME和硫酸盐还原菌(Deltaproteobacteria);深海热液区由于具有化学物质的多样性和快速的动态变化而导致形成微生物的高度多样性.洋壳主要由基性、超基性岩构成,含有丰富的矿物,其中不乏参与铁、锰、硫等关键代谢反应的化能自养微生物.同时,由于环境中99％以上的微生物没有已培养的亲缘种,因此对深海微生物的多样性、生理功能特性以及生物地球化学作用的理解和研究仍然存在巨大的挑战.本文将尝试从不同的深海环境分区来综述深海海水、沉积物、洋壳,以及冷泉区和热液口等特殊生态环境中微生物的分布和多样性.     

极端微生物及其适应机理的研究进展

极端微生物是生物对极端环境适应的特殊种类 ,研究极端微生物的特性对探索生命的起源、微生物的育种及开发利用等具有重要意义。从嗜热微生物、嗜冷菌和耐冷菌、极端嗜酸微生物、嗜碱微生物、嗜盐微生物、嗜压微生物等方面总结了极端微生物及其适应机理的多样性以及其研究进展 ,旨在为极端微生物的开发利用提供一定的参考依据。     

第六届全国微生物资源学术暨国家微生物资源平台运行服务研讨会

<正>微生物是地球上生物多样性最为丰富的资源,其生物多样性在维持生物圈和为人类提供广泛而大量的未开发资源方面起着主要的作用。海洋,占地球面积约71%,是生命的最初起源地;其中蕴藏着丰富的、最具优势和特色的海洋微生物资源。海洋以其独特、复杂的生态系统为海洋微生物的物种多样性提供了重要支撑。海洋微生物具备的与高压、高盐、低温、寡营养等极     

南极冰下水生态系统微生物与生源元素循环研究进展

南极大陆冰盖下存在液态水,形成了由冰下湖、冰下河/溪、冰封湖和冰架下水体等组成的冰下水生态系统,具有低温、黑暗和寡营养等极端的环境条件特征。微生物主导了南极冰下水生态系统,其具有丰富多样的种群构成、功能形式和独特的适应机制,在生源元素生物地球化学循环过程中起了重要作用。研究南极冰下微生物群落的生态特征及其参与的生源元素地球化学循环过程,可为揭示地球生命演化和探索外星生命提供指示,具有重要的科学意义。本文综述了南极冰下水生态系统的极端环境条件、冰下微生物的多样性、冰下微生物参与的生物地球化学循环以及冰下微生物的适极机理,最后基于研究现状展望了南极冰下微生物的未来研究方向。     

搏浪撷珍会有时,制得灵药谢众生 海洋药物研发

人类对海洋的探索永无止境。海洋孕育着生命,同时也蕴含着治愈人类重大疾病的宝藏和机遇。浩瀚的大海是生物多样性的宝库,蕴藏着地球上还未被人类开发利用的丰富海洋生物及其天然产物资源。特殊环境下的奇异生命体联系海洋环境是一个开放且独特的生态系统,高盐、高压、局部高温或者低温、寡营养等恶劣的生存条件,使得海洋生物的生存竞争比陆地生物激烈得多,因此各种海洋动植物与微生物共生互作的现象非常普遍,它们相互适应、相互依存、协同进化,形成了一个特殊复杂而又奇妙的体系。     

地微生物学研究热点之一

地球表层或地球内部的一切极端环境中生存微生物是一个潜在的资源宝库。曾报道在温泉、深海热液出口交接处有嗜热细菌的存在,源于这些细菌含有很强的嗜极酶、如耐热酶、蛋白质及其他细胞组分,有些嗜热酶进入实用化,商品化。有的嗜热细菌全部基因组测序工作的完成,对嗜极酶基因组的研究与探索以及对嗜热菌适应极端环境的生存和繁衍与分子机制的研究有重要价值。这是深海火山口嗜热微生物研发的一个热点,也是地微生物学研究的新领域。英国“自然”(2005．元月)报道,地中海深处含盐量极高的4个盐盆地区,有一群活着的微生物,该地区水的含盐量极高,比酱油成2倍,这些微生物照样维持它们的生命活动。     

古细菌及其在人类疾病中可能的作用

长期以来,人们一直在努力寻找在一些特殊环境条件下(如极端的pH、温度、营养条件和压力)下生存的微生物,并得到了大量关于生物多样性和微生物生命起源的信息。古细菌是一个数量多、变异大的原核生物组,它包括很多生活在极限条件如高温温泉、盐湖和深海火山口的生物。令人不解的是,尽管古细菌是地球上广泛存在的微生物,但目前还没有发现它与人类疾病有关。     

一份南海深海沉积物样品中可培养细菌的多样性

海洋沉积环境蕴含丰富的微生物资源。对深海难培养微生物的分离培养,不仅有利于深海微生物资源的挖掘与利用,也有利于对深海微生物学的研究。本研究采用多种培养基分离获得细菌菌株纯培养,并通过16S r RNA基因序列鉴定,对我国南海海域1个4 000 m水深的深海表层沉积物样品的可培养细菌多样性进行初探。共设计23种分离培养基,经过选择性分离培养最终获得612株细菌菌株,分别隶属于厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)和拟杆菌门(Bacteroidetes)的9目10科27个属级类群,可培养优势类群为厚壁菌门,占所有分离物种数量的85.8%,包含13个16S rRNA基因序列相似性低于98%的潜在新物种。海洋琼脂类培养基适合培养不同种类的海洋细菌类群,放线菌选择性分离类合成培养基对放线菌类群的分离效果较好。最终获得一些与具有产抗生素、细胞毒素、高效酶活、耐受不良环境、降解污染物等特殊功能微生物相近的菌株。研究结果表明,该深海沉积物样品的可培养微生物资源、潜在新物种和微生物生理特性丰富多样,研究深海环境难培养微生物的分离策略及其微生物适应生理特性对研究极端环境微生物打下了基础。     

极端微生物及其应用研究进展

极端微生物是指在高/低温、高/低pH、高盐、高压等极端环境条件下生存的微生物.特殊的生存条件导致其具有特殊的遗传背景和代谢途径,并可产生功能特殊的酶类和活性物质.随着系统生物学和合成生物学技术的发展,极端微生物作为一类特殊的微生物群体,在生物医疗、生物能源和生物材料等领域具有巨大的应用潜力.极端微生物相关研究也对生命起...     

Culturability and Secondary Metabolite Diversity of Extreme Microbes: Expanding Contribution of Deep Sea and Deep-Sea Vent Microbes to Natural Product Discovery

Microbes from extreme environments do not necessarily require extreme culture conditions. Perhaps the most extreme environments known, deep-sea hydrothermal vent sites, support an incredible array of archaea, bacteria, and fungi, many of which have now been cultured. Microbes cultured from extreme environments have not disappointed in the natural products arena; diverse bioactive secondary metabolites have been isolated from cultured extreme-tolerant microbes, extremophiles, and deep-sea microbes. The contribution of vent microbes to our arsenal of natural products will likely grow, given the culturability of vent microbes; their metabolic, physiologic, and phylogenetic diversity; numerous reports of bioactive natural products from microbes inhabiting high acid, high temperature, or high pressure environments; and the recent isolation of new chroman derivatives and siderophores from deep-sea hydrothermal vent bacteria.     

Biochemical and thermodynamic analyses of energy conversion in extremophiles

A variety of extreme environments, characterized by extreme values of various physicochemical parameters (temperature, pressure, salinity, pH, and so on), are found on Earth. Organisms that favorably live in such extreme environments are called extremophiles. All living organisms, including extremophiles, must acquire energy to maintain cellular homeostasis, including extremophiles. For energy conversion in harsh environments, thermodynamically useful reactions and stable biomolecules are essential. In this review, I briefly summarize recent studies of extreme environments and extremophiles living in these environments and describe energy conversion processes in various extremophiles based on my previous research. Furthermore, I discuss the correlation between the biological system of electrotrophy, a third biological energy acquisition system, and the mechanism underlying microbiologically influenced corrosion. These insights into energy conversion in extremophiles may improve our understanding of the “limits of life”.

Abbreviations: PPi: pyrophosphate; PPase: pyrophosphatase; ITC: isothermal titration microcalorimetry; SVNTase: Shewanella violacea 5?-nucleotidase; SANTase: Shewanella amazonensis 5?-nucleotidase     

Microbial diversity of deep-sea extremophiles--Piezophiles, Hyperthermophiles, and subsurface microorganisms]

Knowledge of our Planet's biosphere has increased tremendously during the last 10 to 20 years. In the field of Microbiology in particular, scientists have discovered novel "extremophiles", microorganisms capable of living in extreme environments such as highly acidic or alkaline conditions, at high salt concentration, with no oxygen, extreme temperatures (as low as -20 degrees C and as high as 300 degrees C), at high concentrations of heavy metals and in high pressure environments such as the deep-sea. It is apparent that microorganisms can exist in any extreme environment of the Earth, yet already scientists have started to look for life on other planets; the so-called "Exobiology" project. But as yet we have little knowledge of the deep-sea and subsurface biosphere of our own planet. We believe that we should elucidate the Biodiversity of Earth more thoroughly before exploring life on other planets, and these attempts would provide deeper insight into clarifying the existence of extraterrestrial life. We focused on two deep-sea extremophiles in this article; one is "Piezophiles", and another is "Hyperthermophiles". Piezophiles are typical microorganisms adapted to high-pressure and cold temperature environments, and located in deep-sea bottom. Otherwise, hyperthermophiles are living in high temperature environment, and located at around the hydrothermal vent systems in deep-sea. They are not typical deep-sea microorganisms, but they can grow well at high-pressure condition, just like piezophiles. Deming and Baross mentioned that most of the hyperthermophilic archaea isolated from deep-sea hydrothermal vents are able to grow under conditions of high temperature and pressure, and in most cases their optimal pressure for growth was greater than the environmental pressure they were isolated from. It is possible that originally their native environment may have been deeper than the sea floor and that there had to be a deeper biosphere. This implication suggests that the deep-sea hydrothermal vents are the windows to a deep subsurface biosphere. A vast array of chemoautotrophic deep-sea animal communities have been found to exist in cold seep environments, and most of these animals are common with those found in hydrothermal vent environments. Thus, it is possible to consider that the cold seeps are also one of slit windows to a deep subsurface biosphere. We conclude that the deep-sea extremophiles are very closely related into the unseen majority in subsurface biosphere, and the subsurface biosphere probably concerns to consider the "exobiology".     

Extremophiles as a source for novel enzymes

Microbial life does not seem to be limited to specific environments. During the past few decades it has become clear that microbial communities can be found in the most diverse conditions, including extremes of temperature, pressure, salinity and pH. These microorganisms, called extremophiles, produce biocatalysts that are functional under extreme conditions. Consequently, the unique properties of these biocatalysts have resulted in several novel applications of enzymes in industrial processes. At present, only a minor fraction of the microorganisms on Earth have been exploited. Novel developments in the cultivation and production of extremophiles, but also developments related to the cloning and expression of their genes in heterologous hosts, will increase the number of enzyme-driven transformations in chemical, food, pharmaceutical and other industrial applications.     

First Insights into the Viral Communities of the Deep-sea Anoxic Brines of the Red Sea

The deep-sea brines of the Red Sea include some of the most extreme and unique environments on Earth. They combine high salinities with increases in temperature, heavy metals,hydrostatic pressure, and anoxic conditions, creating unique settings for thriving populations of novel extremophiles. Despite a recent increase of studies focusing on these unusual biotopes, their viral communities remain unexplored. The current survey explores four metagenomic datasets obtained from different brine–seawater interface samples, focusing specifically on the diversity of their viral communities. Data analysis confirmed that the particle-attached viral communities present in the brine–seawater interfaces were diverse and generally dominated by Caudovirales,yet appearing distinct from sample to sample. With a level of caution, we report the unexpected finding of Phycodnaviridae, which infects algae and plants, and trace amounts of insect-infecting Iridoviridae. Results from Kebrit Deep revealed stratification in the viral communities present in the interface: the upper-interface was enriched with viruses associated with typical marine bacteria,while the lower-interface was enriched with haloviruses and halophages. These results provide first insights into the unexplored viral communities present in deep-sea brines of the Red Sea, representing one of the first steps for ongoing and future sampling efforts and studies.     

Extremolytes: natural compounds from extremophiles for versatile applications

Extremophilic microorganisms have adopted a variety of ingenious strategies for survival under high or low temperature, extreme pressure, and drastic salt concentrations. A novel application area for extremophiles is the use of “extremolytes,” organic osmolytes from extremophilic microorganisms, to protect biological macromolecules and cells from damage by external stresses. In extremophiles, these low molecular weight compounds are accumulated in response to increased extracellular salt concentrations, but also as a response to other environmental changes, e.g., increased temperature. Extremolytes minimize the denaturation of biopolymers that usually occurs under conditions of water stress and are compatible with the intracellular machinery at high (>1 M) concentrations. The ectoines, as the first extremolytes that are produced in a large scale, have already found application as cell protectants in skin care and as protein-free stabilizers of proteins and cells in life sciences. In addition to ectoines, a range of extremolytes with heterogenous chemical structures like the polyol phosphates di-myoinositol-1,1′-phosphate, cyclic 2,3-diphosphoglycerate, and α-diglycerol phosphate and the mannose derivatives mannosylglycerate (firoin) and mannosylglyceramide (firoin-A) were characterized and were shown to have protective properties toward proteins and cells. A range of new applications, all based on the adaptation to stress conditions conferred by extremolytes, is in development.     

嗜热β-甘露聚糖酶的研究进展

β-甘露聚糖酶在生物能源、饲料、食品和纺织等工业中均有着重要的应用前景。其属于半纤维素酶类,广泛存在于动植物和微生物中,微生物来源尤为广泛。随着极端微生物和极端酶的广泛研究,嗜热甘露聚糖酶因其在高温环境中具有较高酶活性和稳定性而倍受关注,并取得了较大的研究进展。本文综述了β-甘露聚糖酶的来源、分类和水解催化方式,以及嗜热甘露聚糖酶的优势和其在基因资源挖掘、重组表达以及分子改良方面的研究进展,展望了嗜热β-甘露聚糖酶未来可能的研究方向和发展前景。     

Tardigrades in Space Research - Past and Future

To survive exposure to space conditions, organisms should have certain characteristics including a high tolerance for freezing, radiation and desiccation. The organisms with the best chance for survival under such conditions are extremophiles, like some species of Bacteria and Archea, Rotifera, several species of Nematoda, some of the arthropods and Tardigrada (water bears). There is no denying that tardigrades are one of the toughest animals on our planet and are the most unique in the extremophiles group. Tardigrada are very small animals (50 to 2,100 μm in length), and they inhabit great number of Earth environments. Ever since it was proven that tardigrades have high resistance to the different kinds of stress factors associated with cosmic journeys, combined with their relatively complex structure and their relative ease of observation, they have become a perfect model organism for space research. This taxon is now the focus of astrobiologists from around the world. Therefore, this paper presents a short review of the space research performed on tardigrades as well as some considerations for further studies.     

Extremotolerance in fungi: evolution on the edge

Our planet offers many opportunities for life on the edge: high and low temperatures, high salt concentrations, acidic and basic conditions and toxic environments, to name but a few extremes. Recent studies have revealed the diversity of fungi that can occur in stressful environments that are hostile to most eukaryotes. We review these studies here, with the additional purpose of proposing some mechanisms that would allow for the evolutionary adaptation of eukaryotic microbial life under extreme conditions. We focus, in particular, on life in ice and life at high salt concentrations, as there is a surprising similarity between the fungal populations in these two kinds of environments, both of which are characterized by low water activity. We propose steps of evolution of generalist species towards the development of specialists in extreme habitats. We argue that traits present in some fungal groups, such as asexuality, synthesis of melanin-like pigments and a flexible morphology, are preadaptations that facilitate persistence and eventual adaptation to conditions on the ecological edge, as well as biotope switches. These processes are important for understanding the evolution of extremophiles; moreover, they have implications for the emergence of novel fungal pathogens.