嗜酸氧化亚铁硫杆菌基因组学研究进展

嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidan,A.ferrooxidans)广泛存在于酸性矿物废水中,与生物冶金和环境净化紧密相关。不同来源嗜酸氧化亚铁硫杆菌全基因组的测序,为我们利用比较基因组学和功能基因组学的方法去洞察嗜酸氧化亚铁硫杆菌功能基因,提供了坚实的研究基础和丰富的科研信息。简述了嗜酸氧化亚铁硫杆菌基因组学的基本特征;从比较基因组学和功能基因组学发现了嗜酸氧化亚铁硫杆菌菌株基因组水平的差异;通过生物信息学概述了该菌的铁和硫代谢机制,并从细菌的功能基因组学对其在生物冶金与环境治理等应用进行了展望。     

酸性矿山废水对底栖藻类的影响

酸性矿山废水中低的pH和高浓度的重金属对水生态系统影响巨大.依据"参照(Control)-受损(Impaired)-恢复(Recovery)"的设计方法,对高岚河受酸性矿山废水影响的河段、不受影响的河段及恢复河段进行对比分析.结果表明底栖藻类密度、叶绿素a浓度、无灰干重及自养指数等受酸性矿山废水影响明显,且枯水期酸性矿山废水的影响更显著.相关分析表明自养指数与各金属显著正相关而与pH值显著负相关,可以很好地指示矿山酸性废水对底栖藻类的影响.     

极端嗜酸微生物

一般认为,极端嗜酸微生物指那些生长ｐＨ上限为３．０最适生长ｐＨ在１．０～２．５之间的微生物。它们一般分布于金属硫矿床酸性矿水、生物滤沥堆、煤矿床酸性矿水以及合硫温泉和土壤中,包括原核和真核两大类。其中原核嗜酸微生物依生长的温度范围不同又可划分成常温型、中温型和高温型３个类群。由于嗜酸微生物在低品位矿生物滤沥及煤的脱硫等方面有重要应用前景,因此受到广泛重视。１极端嗜酸微生物的多样性及主要类群在极端酸性环境中的真核生命几乎完全限于微生物。在黄石公园的温泉水体中已分离到光合作用的藻类。从其它一些地方金…     

葡萄糖对嗜酸氧化亚铁硫杆菌与Acidiphilium acidophilum共培养的影响

【目的】深入了解自养的嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)与异养的Acidiphilium acidophilum之间的协同作用, 为嗜酸异养微生物在生物浸出体系和酸性矿坑水(AMD)等极端酸性环境中的生态功能研究提供基础, 并为AMD环境的修复提供参考。【方法】应用实时荧光定量PCR (RT-qPCR)及特异性引物, 定量At. ferrooxidans与Aph. acidophilum在类似自然状态下的共培养物受葡萄糖抑制时的生物量变化, 同时检测其生长过程中Fe2+氧化和pH值的变化。【结果】无论是否加入葡萄糖, 共培养对Fe2+氧化的效率均较At. ferrooxidans纯培养高。当葡萄糖浓度为5 g/L时, At. ferrooxidans纯培养失去对Fe2+的氧化能力, 而共培养仍能在100 h内将所有的Fe2+氧化完, 且加入葡萄糖越多的培养体系氧化终点的pH值也越高。在不加入葡萄糖的条件下, At. ferrooxidans 与Aph. acidophilum 数量比在100:1的数量级, 表明以这两种菌为代表的自养菌和异养菌在自然条件下生物量的比例。无论纯培养还是共培养的At. ferrooxidans数量均随葡萄糖浓度的提高而减少, 且延滞期则变长; 而异养生长的Aph. acidophilum则相反。【结论】适合进行Fe2+氧化的At. ferrooxidans与Aph. acidophilum的数量比例范围应在100:1的数量级。由于Aph. acidophilum能促进At. ferrooxidans对亚铁的氧化, 并能缓解或消除葡萄糖对At. ferrooxidans的抑制, 所以不能以加入类似于葡萄糖的有机物作为AMD环境生物修复的手段。     

嗜酸菌研究进展

极端环境微生物是当今生命科学领域的研究热点。嗜酸菌是极端环境微生物的重要类群,在人们生活生产中发挥着巨大的作用。介绍了嗜酸菌的主要类群及特征,阐述了它们在自然界的主要行为、适应酸和重金属的生理机制以及分子遗传学研究进展,最后介绍了嗜酸菌在实际生产中的主要应用。     

嗜酸性硫杆菌抗铜机制研究进展

嗜酸性硫杆菌是一类重要的浸矿微生物,其抗铜机制研究备受人们关注.本文在分析相关文献的基础上,从嗜酸性硫杆菌对铜的耐受能力、细胞质中铜的外排、细胞周质中铜浓度的控制、无机多聚磷酸盐参与铜的解毒、新发现的基因组岛和氧化压力应激反应等方面对当前的研究进展进行综述,并对未来相关研究方向做出展望,旨在为嗜酸性硫杆菌抗铜机制的深入研究提供参考.     

嗜盐微生物在环境修复中的研究进展

人类活动产生的污染物,使一些天然盐环境遭受不同程度的污染,或者使环境受到污染物与高盐的双重污染。在高盐条件下,非嗜盐微生物的代谢会受到抑制,其生物修复效率明显降低,甚至丧失修复能力。嗜盐微生物则能够在高盐环境中栖息繁殖,凸显其修复被污染高盐环境的生物学效率和广阔的应用前景。就嗜盐微生物降解石油烃、芳香烃衍生物和有机磷等污染物的研究进展进行了综述和讨论。     

一株嗜酸兼性异养菌的分离和系统发育分析

从广东大宝山矿区硫化矿酸性矿坑水中分离获得一株嗜酸兼性异养菌DBS4-1,对该菌株进行了形态、生理生化特性研究及16S rRNA序列分析。分析结果显示:该菌株为革兰氏阴性细菌,球状,菌体直径约为4.0±0.5μm;该菌株兼性异养,具有广泛的底物利用特性,可以利用有机物进行异养生长,同时在自养环境中,还可以利用三价铁、单质硫获得能量进行生长,最适生长温度为30℃左右,最适生长pH约为3.5;该菌16S rRNA序列与Thiobacillus acidophilus(D86511)同源性高达99%。结果表明DBS4-1属于嗜酸硫杆菌属(Acidiphilium sp.),嗜酸种(acidophilum)。     

来源于酸热脂环酸杆菌的嗜酸性α-淀粉酶的表达研究

从嗜酸耐热的酸热脂环酸杆菌Alicyclobacillusacidocaldarius中克隆到α_淀粉酶的基因 (amy) ,该基因全长 390 3bp ,编码130 1个氨基酸 ,理论分子量约 140kD。将基因amy分别克隆到大肠杆菌E .coli表达载体pET-2.2b(+)和毕赤酵母P .pastoris表达载体pPIC9α ,并在大肠杆菌和毕赤酵母中得到了表达 ,表达产物具有淀粉酶的活性。对酵母中表达的酶蛋白AMY进行了纯化 ,并初步研究了它的酶学性质 ,它的作用最适pH3.2 ,在pH 2.5～4.6范围内 ,酶活性保留 50%以上 ,它的最适温度65℃ ,在 70℃下处理 30min ,酶活性维持50%以上 ,基本保留了天然酶蛋白的耐热性和嗜酸性。位于基因amy内部 +1174～+3288bp的基因片段amy′全长 2115bp ,编码705个氨基酸 ,在E .coli表达后依然具有淀粉酶的活性。     

嗜酸菌及其应用

自然界大多数环境的pH值为5～9,它适合多数微生物生长。嗜酸菌是一种能在低pH条件下生长和繁殖的极端环境微生物［‘－’］,通常在pHZ～5生长很好,pHS．5以上生长不好。有些嗜酸菌在中性pH条件下根本不生长,如氧化硫硫杆菌（Thiobacillusthiootidans）,酸热硫化叶菌（deghlobusacidocaldarius）,酸热芽抱杆菌O沏ciousacidoca儿brius）等,最佳生长pH是2．0～3．0,这些都是专性嗜酸菌。一些真菌也能在pHS．0或更低条件下生长,实际上是耐酸菌。l嗜酸菌生态分布及其对环境适应机制嗜酸菌生长在酸性环境,这主要与硫或硫化物的存在…     

Ecophysiology of algae living in highly acidic environments

Highly acidic environments are inhabited by acidophilic as well as acidotolerant algae. Acidophilic algae are adapted to pH values as low as 0.05 and unable to grow at neutral pH. A prerequisite for thriving at low pH is the reduction of proton influx and an increase in proton pump efficiency. In addition, algae have to cope with a limited supply of carbon dioxide for photosynthesis because of the absence of a bicarbonate pool. Therefore, some algae grow mainly in near terrestrial situations to increase the CO₂-availability or actively move within the water body into areas with high CO₂. Beside these direct effects of acidity, high concentrations of heavy metals and precipitation of nutrients cause indirect effects on the algae in many acidic environments.     

Quantitative proteomic analyses of the response of acidophilic microbial communities to different pH conditions

Extensive genomic characterization of multi-species acid mine drainage microbial consortia combined with laboratory cultivation has enabled the application of quantitative proteomic analyses at the community level. In this study, quantitative proteomic comparisons were used to functionally characterize laboratory-cultivated acidophilic communities sustained in pH 1.45 or 0.85 conditions. The distributions of all proteins identified for individual organisms indicated biases for either high or low pH, and suggests pH-specific niche partitioning for low abundance bacteria and archaea. Although the proteome of the dominant bacterium, Leptospirillum group II, was largely unaffected by pH treatments, analysis of functional categories indicated proteins involved in amino acid and nucleotide metabolism, as well as cell membrane/envelope biogenesis were overrepresented at high pH. Comparison of specific protein abundances indicates higher pH conditions favor Leptospirillum group III, whereas low pH conditions promote the growth of certain archaea. Thus, quantitative proteomic comparisons revealed distinct differences in community composition and metabolic function of individual organisms during different pH treatments. Proteomic analysis revealed other aspects of community function. Different numbers of phage proteins were identified across biological replicates, indicating stochastic spatial heterogeneity of phage outbreaks. Additionally, proteomic data were used to identify a previously unknown genotypic variant of Leptospirillum group II, an indication of selection for a specific Leptospirillum group II population in laboratory communities. Our results confirm the importance of pH and related geochemical factors in fine-tuning acidophilic microbial community structure and function at the species and strain level, and demonstrate the broad utility of proteomics in laboratory community studies.     

Ecogeochemistry of the subsurface food web at pH 0–2.5 in Iron Mountain,California, U.S.A.

Pyrite oxidation in the underground mining environment of Iron Mountain, California, has created the most acidic pH values ever reported in aquatic systems. Sulfate values as high as 120000 mg l^–1 and iron as high as 27600 mg l^–1 have been measured in the mine water, which also carries abundant other dissolved metals including Al, Zn, Cu, Cd, Mn, Sb and Pb. Extreme acidity and high metal concentrations apparently do not preclude the presence of an underground acidophilic food web, which has developed with bacterial biomass at the base and heliozoans as top predators. Slimes, oil-like films, flexible and inflexible stalactites, sediments, water and precipitates were found to have distinctive communities. A variety of filamentous and non-filamentous bacteria grew in slimes in water having pH values <1.0. Fungal hyphae colonize stalactites dripping pH 1.0 water; they may help to form these drip structures. Motile hypotrichous ciliates and bdelloid rotifers are particularly abundant in slimes having a pH of 1.5. Holdfasts of the iron bacterium Leptothrix discophora attach to biofilms covering pools of standing water having a pH of 2.5 in the mine. The mine is not a closed environment – people, forced air flow and massive flushing during high intensity rainfall provide intermittent contact between the surface and underground habitats, so the mine ecosystem probably is not a restricted one.     

Microcosm-based Study of the Attenuation of an Acid Mine Drainage-Impacted Site through Biological Sulfate and Iron Reduction

Acid mine drainage is a widespread environmental problem and is characterized by elevated proton, sulfate, and dissolved iron concentrations. To understand the driving forces behind the attenuation of AMD, we compared microcosms using sediment and groundwater collected at Davis Mine, Massachusetts, a site where both generation and attenuation of AMD occur. A shift in key geochemical parameters over time was due to the natural microbial population, which was supported by detailed molecular biology results. The attenuation of AMD was stimulated through amendment with glycerol, with nitrogen and phosphorous, or with algae extract, but not by wood chips, suggesting the addition of different organic electron donors as a bioremediation strategy.     

Comparison of microbial community composition and activity in sulfate-reducing batch systems remediating mine drainage

Five microbial inocula were evaluated in batch tests for the ability to remediate mine drainage (MD). Dairy manure (DM), anaerobic digester sludge, substrate from the Luttrell (LUTR) and Peerless Jenny King (PJK) sulfate-reducing permeable reactive zones (SR-PRZs) and material from an MD-treatment column that had been inoculated with material from a previous MD-treatment column were compared in terms of sulfate and metal removal and pH neutralization. The microbial communities were characterized at 0, 2, 4, 9, and 14 weeks using denaturing gradient gel electrophoresis and quantitative polymerase chain reaction to quantify all bacteria and the sulfate-reducing bacteria of the genus Desulfovibrio. The cultures inoculated with the LUTR, PJK, and DM materials demonstrated significantly higher rates of sulfate and metal removal, and contained all the microorganisms associated with the desired functions of SR-PRZs (i.e., polysaccharide degradation, fermentation, and sulfate reduction) as well as a relatively high proportion of Desulfovibrio spp. These results demonstrate that inoculum influences performance and also provide insights into key aspects of inoculum composition that impact performance. This is the first systematic biomolecular examination of the relationship between microbial community composition and MD remediation capabilities.     

Phytohormones in algae

In various algal taxa, essentially all known phytohormones were detected in concentrations comparable with their content in higher plants. The occurrence of diverse free and conjugated hormone forms substantiates the functioning of the complex system of metabolism and activity regulation of these compounds. In most cases, the spectrum of biological activities of algal hormones corresponds to the functions of higher plant hormones. Some physiological and biochemical processes in algal cells and tissues are under the control of several phytohormones. All these facts permit a consideration of the algal hormonal system as a full-value regulatory system.     

THE OPTIMUM PH OF FOUR STRAINS OF ACIDOPHILIC SNOW ALGAE IN THE GENUS CHLOROMONAS (CHLOROPHYTA) AND POSSIBLE EFFECTS OF ACID PRECIPITATION1

Four axenic strains of snow algae were examined for optimum pH under laboratory conditions using M-1 growth medium. Growth was measured using cell counts, cell measurements and absorbance readings at 440 nm. Strains C204 and C479A of Chloromonas sp. from the Adirondack Mountains, New York, grew optimally at pH 4.0 to 5.0. Strains C381F and C381G, Chloromonas polyptera (Fritsch) Hoh., Mull. & Roem. from the White Mountains, Arizona, grew optimally at pH 4.5 to 5.0. Growth was significantly higher at pH 4.0 in the northeastern species (Chloromonas sp.), but no significant difference was observed in final growth at pH 4.5, 5.0 and 5.5 between species. It is postulated that the more acidic precipitation in the northeastern United States may be selecting for strains of snow algae with greater tolerance to acidity than in strains from the southwestern United States or that the different pH optima reported are simply species differences. New York strain C204 was also grown in heavily buffered AM medium where it had an optimum pH of 5.0, but cells became irregularly shaped and tended to clump at pH 6.0 to 7.0. Growth of C204 in AM medium was significantly lower than in M-1 medium for snow algae. These findings justify the use of M-1 medium for this type of experimentation.     

Green algae in tundra soils affected by coal mine pollutions

Green algal communities were investigated in clean and pollution-impacted tundra soils around the large coal mine industrial complex of Vorkuta in the E. European Russian tundra. Samples were collected in three zones of open-cast coal mining with different degrees of pollution-impacted soil transformation. A total of 42 species of algae were found in all zones. The species richness decreased from 27 species in undisturbed zones to 19 species in polluted zones. Under open-cast coal mining impacts the community structure simplified, and the dominant algae complexes changed. Algae that are typical for clean soils disappeared from the communities. The total abundance of green algae (counted together with Xanthophyta) ranged between 100–120 × 10³ (cells/g dry soils) in undisturbed zones and 0.5–50 × 10³ in polluted zones. Soil algae appear to be better indicators of coal mine technogenic pollution than flowering plants and mosses. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.