Diversity of bacteria and archaea from two shallow marine hydrothermal vents from Vulcano Island

Extremophiles - To obtain new insights into community compositions of hyperthermophilic microorganisms, defined as having optimal growth temperatures of 80 °C and above, sediment and...     

Diversity at hydrothermal vents

Aim To describe patterns of hydrothermal vent community diversity and dispersion at the intersegment scale (> 100 km). Location The area discussed is an approximately 170 km portion of the Juan de Fuca Ridge, a mid‐ocean ridge in the north‐east Pacific Ocean. Methods Samples of benthic invertebrates from hydrothermal vents on three segments of the Juan de Fuca are examined for community characteristics such as diversity, abundance and distribution. Results Species richness (55 species) and evenness are low. If the macrofauna only are considered, species richness is about 30% lower than when meiofauna are also considered. The geometric series describes the species‐abundance distribution. The relationship between vent species’ distribution and abundance is significantly positive (r² = 0.818; P < 0.001). Alpha diversity is lower in patchy habitat than continuous habitat and gamma diversity is similar for both habitat types. Beta diversity is higher in patchy habitat. Local diversity is linearly related to regional diversity. Main conclusions Species richness is comparable to other highly disturbed systems. The geometric series species abundance model implies some degree of niche pre‐emption in the vent community and is consistent with the suggestion that the geometric series distribution can be found in species‐poor environments that experience harsh conditions and are structured by relatively few environmental factors. Species distribution and abundance are highly correlated. The regional species pool affects local vent diversity. Vent diversity studies should be conducted on at least the ridge scale.     

Sulfate reduction and trichloroethylene biodegradation by a marine microbial community from hydrothermal vents sediments

Sulfate reduction (SR) and trichloroethylene (TCE) biodegradation at two different temperatures (37 and 70 °C) were investigated in enrichment cultures prepared with two different samples of sediments collected from hydrothermal vents. The unadapted sediments were incubated with sulfate (4 g L⁻¹) as the electron acceptor before TCE addition to enrich them in biomass and to establish a constant sulfate reduction (SR, 87% sulfate conversion and specific H₂S concentration of 90.81 ± 8.19 mg H₂S g VSS⁻¹), afterwards TCE was added at an initial concentration of 300 ??mol L⁻¹. The best results for TCE biodegradation were obtained at 37 °C. At this temperature, SR was up to 92%, whereas TCE biodegradation reached 75% and ethane was detected as the main degradation product. Under thermophilic conditions (70 °C) TCE biodegradation reached up to approximately 60% and the SR was 30% in 30 days of incubation with the chlorinated solvent. Along with these results, the 16S rDNA analysis from samples at 37 °C showed the presence of bacteria belonging to the genera: Clostridium, Bacillus and Desulfuromonas. The overall results on TCE degradation and SR suggest that cometabolic TCE degradation is carried out by sulfate or sulfur reducers and fermentative bacteria at mesophilic conditions.     

Antarctic marine biodiversity and deep-sea hydrothermal vents

The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea hydrothermal vents. Vent ecosystems have been documented from many sites across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea hydrothermal vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic hydrothermal vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea hydrothermal vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.     

北戴河海洋沉积物中L-半胱氨酸脱硫细菌的多样性及其特性

【背景】脱硫细菌对有机硫的脱硫作用在硫的生物地球化学循环以及脱硫工业中都起着重要的作用。【目的】了解海洋沉积物中可分解有机物产生硫化氢的细菌多样性。【方法】对我国北戴河海洋沉积物中可培养的L-半胱氨酸脱硫细菌进行分离与筛选,通过对其16SrRNA基因序列测定与分析,构建系统发育树,并对其脱硫、脱氮能力进行检验。【结果】从海洋沉积物中分离得到97株细菌,从以L-半胱氨酸为硫源的培养基中筛选出62株有机脱硫专一型细菌。根据脱硫细菌的形态及其特征,从中选取12株作为典型代表做进一步分析,它们分别属于芽孢杆菌属(Bacillus)、赖氨酸芽孢杆菌属(Lysinibacillus)、动性球菌属(Planococcus)和红球菌属(Rhodococcus)。结果表明,这12株细菌均可产生半胱氨酸脱巯基酶,能够将半胱氨酸分解为丙酮酸、硫化氢和氨,即同时具备脱硫与脱氮的能力。其中有5株菌脱硫能力较强,分别属于赖氨酸芽孢杆菌属、动性球菌属和芽孢杆菌属。【结论】海洋沉积物中存在着丰富的L-半胱氨酸脱硫细菌,为进一步研究海洋中硫的生物地球化学循环提供了素材。     

Evaluation of enrichments of sulfate reducing bacteria from pristine hydrothermal vents sediments as potential inoculum for reducing trichloroethylene

The evaluation of enrichments from pristine hydrothermal vents sediments on its capability of reducing trichloroethylene (TCE) under sulfate reducing conditions with lactate and volatile fatty acids (VFAs) as substrates was performed. Effect of the possible TCE biodegradation intermediates cis and trans 1,2 dichloroethenes on sulfate reduction (SR) was also evaluated. The influence of cyanocobalamin (CNB₁₂) and riboflavin (RF) on the SR and biodegradation of TCE was also determined. Sediments from the vents were incubated at 37°C and supplemented with 4 g l⁻¹ SO₄ ²⁻, lactate or VFAs and amended in the corresponding treatments with either CNB₁₂ or RF in separated experiments. A percentage of TCE removal of 86 (150 μmol l⁻¹ initial concentration) was attained coupled to 48% sulfate depletion with lactate as substrate. Up to 93% removal of TCE (300 μmol l⁻¹ initial concentration) and 40% of sulfate was reached for VFAs as electron donor. A combination of lactate and CNB₁₂ yielded the best SR. The overall results suggest a syntrophic association in this microbial community in which sulfate reducers, dehalogenating, and probably halorespiring bacteria may be interacting and taking advantage of the fermentation of substrates differently, but without interruption of SR in spite of the fact that TCE was always present. It was also clear that sulfate reduction must be established in the cultures before any degradation can occur. The microbial community present in these hydrothermal vents sediments could be a new source of inoculum for bioreactors designed for dechlorination purposes.     

舟山群岛海域沉积物厌氧氨氧化细菌多样性

通过构建16S rRNA基因文库和克隆测序研究了舟山海域沉积物中厌氧氨氧化细菌(AAOB)的多样性。从5个克隆文库中共获得297条16S rRNA基因序列,包含16个操作分类单元(OTUs)。离岸距离较近的3个站具有相似的群落结构,且与离岸较远的2个站具有明显差异。系统发育结果显示,Scalindua属是该海域AAOB的优势类群,95.3%的序列与Scalindua属AAOB具有较近的亲缘关系;1条序列与Kuenenia属具有较近的亲缘关系;此外还有15条序列与已知的AAOB相似性较低。相关性分析表明沉积物有机碳含量与多样性指数具有显著正相关,可能是该海域AAOB多样性变化的重要影响因子。     

南极中山站长城站土壤及海洋沉积物可培养细菌多样性

南极地区具有气候酷寒干燥、强紫外(UV)辐射和季节性光照与温度波动等恶劣的极端环境条件,孕育了大量微生物资源和潜在新物种。为了挖掘南极不同生境样品蕴含的微生物菌种资源,更好地认识和探索南极地区微生物资源多样性,利用低温寡营养富集结合梯度稀释涂布的方法,对南极长城站、中山站土壤和近海表层沉积物3个生境的样品进行细菌分离和16S rRNA基因序列相似性分析以确定南极细菌分类学地位。结果表明,共获得482株纯培养细菌,有54个属,142个种,分布于变形菌门(Proteobacteria,42%),放线菌门(Actinobacteria,40%),厚壁菌门(Firmicutes,12%),拟杆菌门(Bacteroidetes,4%)和异常球菌-栖热菌门(Deinococcus-Thermus,1%)。优势属为嗜冷杆菌属(Psychrobacter,12%)、假单胞属(Pseudomonas,10%)和节杆菌属(Arthrobacter,9%)。不同生境样品中纯培养细菌多样性存在较大差异。中山站干燥土壤样品中放线菌门比例明显高于变形菌门,有13个特有属,嗜冷杆菌属(Psychrobacter)、红球菌属(Rhodococcus)为优势菌;长城站近岸砂土样品中变形菌门菌株最多,拟杆菌门比例高于中山站样品,有高比例的假单胞菌,分离到12个特有属;近海沉积物样品细菌群落结构最简单,分离到9个特有属。经16S rRNA基因序列对比发现,有7株菌为潜在新种。     

Production and characterization of exopolysaccharides excreted by thermophilic bacteria from shallow,marine hydrothermal vents of Flegrean Ares (Italy)

Thermophilic microorganisms (4001-4014), described as aerobic or facultatively anaerobic, endospore forming with growth optima temperatures in the range of 60 to 80 degrees C, have been isolated from hot marine springs around Ischia and from hydrothermal vents in the gulf of Naples. Mucous colonies are been selected for the recovery of new strains producing exopolysaccharides (EPS). To induce the biosynthesis of new exopolysaccharides, different sugars were tested as carbon sources in the media. The production of EPS in the strain 4009 reached 60 mg/l using trehalose as carbon source, increasing the yield of about 1000 fold. The 4001-EPS was a mannan with a molecular weight of 380.000 D and with a complex primary structure. In fact, the analysis of the permethylated polysaccharide in GC-MS, showed the presence of mannose, glucose, galactose, mannosamine in the relative ratio of 1:0.1:tr :tr, respectively. Nuclear magnetic resonance spectrum of the exopolysaccharide confirmed the presence of a repetitive unity formed by seven monosaccharides, six with alpha gluco/galacto configuration and one residue with beta conformation.     

Diversity in mussel beds at deep-sea hydrothermal vents and cold seeps

Remarkably little is known about fundamental distinctions (or similarities) between the faunas of deep‐sea hydrothermal vents and seeps. Low species richness at vents has been attributed to the transient nature of vent habitats and to toxic effects of hydrogen sulphide and heavy metals in vent effluents. Seeps are arguably more stable and more chemically benign than vents. They have also been regarded as more diverse, but until now there has not been a rigorous test of this hypothesis. We evaluated diversity indices for invertebrates associated with mussel beds at six vents and two seeps and found that invertebrate diversity was significantly higher at seeps than vents, although some vent mussel beds supported nearly the same diversity as seep mussel beds. Lower diversity at vents may be a consequence of a greater physiological barrier to invasion at vents than at seeps. Diversity was lowest where spacing between vents was greatest, suggesting that risks of extinction as a result of dispersal‐related processes may contribute to the pattern of diversity observed at vents.     

Novel bacterial exopolysaccharides from deep-sea hydrothermal vents

Five bacterial strains recovered from deep-sea hydrothermal vents were studied for their ability to secrete extracellular polymers. A preliminary characterization displayed four different polysaccharides in terms of both chemical composition and rheological properties. One of them was secreted by Alteromonas macleodii subsp. fijiensis and exhibited similarities with xanthan, a commercial polysaccharide. Two of the three Pseudoalteromonas species were shown to produce the same polymer. The last polymer was secreted by a bacterium belonging to the Vibrio genus. They all contained glucose, galactose, mannose, glucuronic and galacturonic acids as the main sugars with the exception of the last one which was only constituted by uronic acids and hexosamines, in that similar to the structure of heparin, a glycosaminoglycan useful in pharmaceutical area. Applications for these polysaccharides could be expected in various biotechnological fields including the food industry, the wastewater treatment and pharmaceutical areas.     

Copepoda from deep-sea hydrothermal vents and cold seeps

Recent explorations of hydrothermal vents in the eastern Pacific (Juan de Fuca spreading zone, Guaymas Basin in the Gulf of California, East Pacific Rise at 21° N and 13° N, and Galapagos Rift) and on the Mid-Atlantic Ridge have revealed many copepods, mostly siphonostomatoids with few poecilostomatoids. In these habitats in depths from 1 808 to 3 650 m water temperatures may reach nearly 15 ° C. Among more than 22 000 copepods from vents examined two new families, 11 new genera, and 32 new species were represented.In addition, two new copepods were found in 3 260 m at cold seeps at the base of the West Florida Escarpment in the Gulf of Mexico, an environment not thermally active, with water temperatures about 4.39 °C.Some of these copepods were associated with host invertebrates such as a Nuculana-like protobranch bivalve, a polychaete, and two species of shrimps. Others were obtained from washings of bivalves or vestimentiferans or by means of corers or slurp guns.     

New gastropods from East Pacific hydrothermal vents

The following new prosobranch species are described: Cyuthermia (gen.n.) naticoides, Lucunoidc (gen.n.) exquisitus (Neomphalidae); Peltospira Iamellifera, Pachydermia (gen.n.) laevis, Depressigyra (gen. n.) g1obulus. D. plunispira, Solutigyra (gen. n.) reticulata, Lirapex (gen. n.) humata, L. granularis (Peltospiridae); Bathymargarites (gen.n.) symplector (Trochidae) and Provanna mucleani (Littorinoidea). Shells and soft parts of the species are described and figured. One species each of Sinezona (Scissurellidae), Moel1rriopsis (Seguenzoidea) and Phymorrhynchus (Turridae) is recorded from East Pacific hydrothermal vents, but not identified to species. Information about feeding biology and type of larval development is given for most of these species. The systematic position of the new species of Neomphalidae and Peltospiridae is considered uncertain, but further anatomical investigations are in progress. The gastropod fauna of East Pacific sulphide-rich environments is summarized and composition, endemism, age. dispersal, predation, adaptations and feeding biology are discussed.     

Phylogenetic diversity of gram-positive bacteria cultured from marine sediments

Major advances in our understanding of marine bacterial diversity have been gained through studies of bacterioplankton, the vast majority of which appear to be gram negative. Less effort has been devoted to studies of bacteria inhabiting marine sediments, yet there is evidence to suggest that gram-positive bacteria comprise a relatively large proportion of these communities. To further expand our understanding of the aerobic gram-positive bacteria present in tropical marine sediments, a culture-dependent approach was applied to sediments collected in the Republic of Palau from the intertidal zone to depths of 500 m. This investigation resulted in the isolation of 1,624 diverse gram-positive bacteria spanning 22 families, including many that appear to represent new taxa. Phylogenetic analysis of 189 representative isolates, based on 16S rRNA gene sequence data, indicated that 124 (65.6%) belonged to the class Actinobacteria while the remaining 65 (34.4%) were members of the class Bacilli. Using a sequence identity value of >/=98%, the 189 isolates grouped into 78 operational taxonomic units, of which 29 (37.2%) are likely to represent new taxa. The high degree of phylogenetic novelty observed during this study highlights the fact that a great deal remains to be learned about the diversity of gram-positive bacteria in marine sediments.     

Comparison of thermophilic methanogens from submarine hydrothermal vents

An extremely thermophilic methanogen was isolated from hydrothermal vent sediment (80°–120° C) collected from the Guaymas Basin, Gulf of California, at a depth of approximately 2000 m. The isolate was a characteristic member of the genus Methanococcus based on its coccoid morphology, ability to produce methane from CO₂ and H₂, and DNA base composition (31.4 mol% G+C); it is distinguished from previously described extremely thermophilic vent methanogens by its ability to grow and produce methane from formate and in the composition of membrane lipids. The temperature range for growth was 48°–94° C (optimum near 85° C); the pH optimum was 6.0. The isolate grew autotrophically but was stimulated by selenium and growth nutrients supplied by yeast extract and trypticase. Extracted polar lipids consisted primarily of diphytanyl glycerol diether (62%), macrocyclic glycerol diether (15.3%), and dibiphytanyl glycerol tetraether (11.8%). Neutral lipids were dominated by a series of C₃₀ isoprenoids; in addition, a novel series of C₃₅ isoprenoids were detected. The isolate appears to be a close relative of the previously described Methanococcus jannaschii, isolated from the East Pacific Rise hydrothermal vent system. From the frequency of isolation, it appears that extremely thermophilic methanococci are the predominant representatives of the methanogenic archaebacteria occurring at deep sea hydrothermal vents.     

南海南沙海域沉积物中可培养微生物及其多样性分析

【目的】为了从南沙海域中分离获得微生物菌种资源,【方法】本文通过沉积物采样、可培养菌分离及16S rRNA鉴定,【结果】从22个站点的沉积物样品中获得349株细菌,分属于87个种。发现产芽孢细菌分布最广,并在10个站点的分离株中占多数;它们是Bacillus,Halobacillus,Brevibacillus,Paenibacillus,Pontibacillus和Thalassobacillus。其中芽孢杆菌（Bacillus）无论在数量上还是种类上都最多,分别属于34种,其中有8个可能的新种。此外,g-Proteobacteria是分离率较高的另一亚群;其中,假单胞菌（Pseudomonas）,海杆菌（Marinobacter）,食烷菌（Alcanivorax）属的细菌最多。统计还发现,在深度750~2000 m之间,低GC含量的细菌最丰富,而深度2000 m以下,分离株则全部为g-Proteobacteria。【结论】南沙沉积物可培养微生物中产芽孢细菌及 g-Proteobacteria比较丰富;其中,产芽孢细菌的多样性最高,具有进一步研究开发价值。     

Thermostable amylolytic enzymes of thermophilic microorganisms from deep-sea hydrothermal vents

Microorganisms-grauling above 60 °C isolated from deep-sea hydrothermal vents were screened for amylolytic activity. Of the 269 strains tested, 70 were found to be positive. Nine archaea (including Thermococcus hydrothermalis AL662 and Thermococcus fumicolans ST557) and one thermophilic bacterium were selected for the determination of thermostability, and the temperature and pH optima of their amylolytic enzymes. Pullulanase, α-glucosidase and α-amylase activities were detected in four archaeal strains (including AL662 and ST557) related to the genus Thermococcus. The anaerobic hyperthermophilic archaeon, Thermococcus hydrothermalis was chosen for the further study of the α-glucosidase activity, and a preliminary characterization of this enzyme was carried out. The small number of highly thermostable α-glucosidases that has been described to date, combined with the very interesting properties of this enzyme, suggest a use for this enzyme in biotechnological processes.