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1.
Anaerobic microbial dehalogenation and its key players in the contaminated Bitterfeld-Wolfen megasite.
Nijenhuis, I, Stollberg, R, Lechner, U
FEMS microbiology ecology. 2018;(4)
Abstract
The megasite Bitterfeld-Wolfen is highly contaminated as a result of accidents and because of dumping of wastes from local chemical industries in the last century. A variety of contaminants including chlorinated ethenes and benzenes, hexachlorohexanes and chlorinated dioxins can still be found in the groundwater and (river) sediments. Investigations of the in situ microbial transformation of organohalides have been performed only over the last two decades at this megasite. In this review, we summarise the research on the activity of anaerobic dehalogenating bacteria at the field site in Bitterfeld-Wolfen, focusing on chlorinated ethenes, monochlorobenzene and chlorinated dioxins. Various methods and concepts were applied including ex situ cultivation and isolation, and in situ analysis of hydrochemical parameters, compound-specific stable isotope analysis of contaminants, 13C-tracer studies and molecular markers. Overall, biotransformation of organohalides is ongoing at the field site and Dehalococcoides mccartyi species play an important role in the detoxification process in the Bitterfeld-Wolfen region.
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2.
Ecology and evolution of seafloor and subseafloor microbial communities.
Orsi, WD
Nature reviews. Microbiology. 2018;(11):671-683
Abstract
Vast regions of the dark ocean have ultra-slow rates of organic matter sedimentation, and their sediments are oxygenated to great depths yet have low levels of organic matter and cells. Primary production in the oxic seabed is supported by ammonia-oxidizing archaea, whereas in anoxic sediments, novel, uncultivated groups have the potential to produce H2 and CH4, which fuel anaerobic carbon fixation. Subseafloor bacteria have very low mutation rates, and their evolution is likely dominated by selection of different pre-adapted subseafloor taxa under oxic and anoxic conditions. In addition, the abundance and activity of viruses indicate that they affect the size, structure and selection of subseafloor communities. This Review highlights how microbial communities survive in the unique, nutrient-poor and energy-starved environment of the seabed, where they have the potential to influence global biochemical cycles.
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3.
[Characteristics of Sediment Oxygen Demand in a Drinking Water Reservoir].
Su, L, Huang, TL, Li, N, Zhang, HH, Wen, G, Li, Y, Chen, JW, Wang, XJ
Huan jing ke xue= Huanjing kexue. 2018;(3):1159-1166
Abstract
Depletion of dissolved oxygen (DO) in the hypolimnetic layer during stratification periods and its deleterious effects on water quality have been widely observed. However, it is still difficult to comprehend conceptually the processes of oxygen consumption at the sediment-water interface. The research presented here is, therefore, based on an areal hypolimnetic oxygen demand (AHOD) model to address three key themes related to the sediment oxygen demand (SOD):① the characteristics of sediment and its influences on SOD; ② evaluation of SOD with different turbulence levels overlying the sediment; and ③ the influence of microbial metabolic activity on SOD. Sediment samples were collected at the entrance to and over the basin area of Jinpen Reservoir, and a sediment-water experimental chamber was designed to achieve these goals. The results showed that, under quiescent conditions, the SOD5area(SOD at DO of 5 mg·L-1) were 0.13 g·(m2·d)-1 and 0.36 g·(m2·d)-1 in the arm and basin, respectively. Under dynamic conditions, the slight mixing of the water column near the sediment induced an increase in SOD and resulted in a gradual shift from first-order to zero-order DO uptake. The organic matter content in the reservoir arm and profundal sediment were 44.43 mg·g-1 and 45.12 mg·g-1, respectively. The microbial metabolic activity in the basin was stronger, and the total fluorescence intensity of the dissolved organic matter (DOM) in the profundal sediments was about 1.5 times that in the reservoir arm. These results suggest that SOD will be higher when microbial metabolic activity is stronger and organic matter content is higher in sediments. The oxygenation aeration techniques should be designed to meet the oxygen demand of the deep reservoir to provide a theoretical basis for improving the oxygenation efficiency.
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4.
Alteromonas oceani sp. nov., isolated from deep-sea sediment of a hydrothermal field.
Jin, QW, Hu, YH, Sun, L
International journal of systematic and evolutionary microbiology. 2018;(2):657-662
Abstract
A novel rod-shaped, Gram-stain-negative, aerobic bacterium, designated S35T, was isolated from deep-sea sediment collected from the Pacmanus hydrothermal field, Manus Basin, Papua New Guinea. Strain S35T grew optimally at 28 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. 16S rRNA gene sequence analysis indicated that strain S35T shared 97.38-98.55% similarity with the type strains of Alteromonas lipolytica, Alteromonas mediterranea and Aestuariibacterhalophilus. Phylogenetic analysis showed that strain S35T belonged to the genus Alteromonas. The strain contained ubiquinone-8 as the predominant respiratory lipoquinone. Summed feature 3 (C16 : 1ω7c and/or C16 : 1ω7c), summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0 were the major fatty acids. The DNA G+C content of strain S35T was 51.3 mol%. These results indicated that strain S35T represents a novel species of the genus Alteromonas, for which the name Alteromonas oceani sp. nov. (type strain S35T=KCTC 52449T=CGMCC 1.16029T) is proposed.
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5.
Fictibacillus iocasae sp. nov., isolated from the deep-sea sediment in Pacmanus, Manus Basin.
Wang, HL, Zhang, J, Sun, L
Archives of microbiology. 2018;(7):1123-1128
Abstract
A novel bacterium, designed strain S38T, was isolated from the deep-sea sediment of Pacmanus hydrothermal field in Manus Basin. The isolate was gram-positive, aerobic, motile, and was defined by endospore-forming rods. Strain S38T grew at 16-38 °C, pH 6-8, and in the presence of 0-7% (w/v) NaCl. Based on 16S rRNA gene sequence, S38T was grouped into the genus Fictibacillus and was most closely related to Fictibacillus phosphorivorans CCM 8426T (97.8%), Fictibacillus nanhaiensis DSM 23009T (97.8%), Fictibacillus halophilus DSM 100124T (97.7%), and Fictibacillus barbaricus DSM 14730T (97.5%). The diagnostic diamino acid of the cell wall was meso-diaminopimelic acid. The major fatty acids were iso-C15:0 and anteiso-C15:0. MK-7 was the predominant respiratory quinone and diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine were the major polar lipids. The genomic DNA G + C content was 46.8 mol%. Phylogenetic analysis, DNA-DNA relatedness, and phenotypic characteristics supported that strain S38T represents a novel species within the genus Fictibacillus, for which the name Fictibacillus iocasae sp. nov. was proposed. The type strain is S38T (= KCTC 33865T = DSM 104298T = CGMCC 1.16031T).
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6.
Description of Bacillus kexueae sp. nov. and Bacillus manusensis sp. nov., isolated from hydrothermal sediments.
Sun, QL, Yu, C, Luan, ZD, Lian, C, Hu, YH, Sun, L
International journal of systematic and evolutionary microbiology. 2018;(3):829-834
Abstract
Two Gram-staining-positive, strictly aerobic bacilli, designated as strains Ma50-5T and Ma50-6T, were isolated from the hydrothermal sediments of Manus Basin in the western Pacific Ocean. Based on 16S rRNA gene sequence, strains Ma50-5T and Ma50-6T were most closely related to Bacillus alveayuensis (97.0 and 97.2 % identity, respectively). The 16S rRNA gene sequence identity between strains Ma50-5T and Ma50-6T was 97.4 %. The identities between strains Ma50-5T and Ma50-6T and other closely related organisms were below 97.0 %. The G+C contents of the genomic DNA of strains Ma50-5T and Ma50-6T were 43.4 and 47.6 mol%, respectively. The major fatty acids (>10 %) of both strains were iso-C15 : 0 and iso-C17 : 0. The predominant isoprenoid quinone detected in both strains was menaquinone-7. Phylogenetic, physiological, biochemical and morphological analyses suggested that strains Ma50-5T and Ma50-6T represent two novel species of the genus Bacillus, for which the names Bacillus kexueae sp. nov. (type strain Ma50-5T=KCTC 33881T=CCTCC AB 2017020T) and Bacillus manusensis sp. nov. (type strain Ma50-6T=KCTC 33882T=CCTCC AB 2017019T), respectively, are proposed.
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7.
Microbial communities in marine sediments modify success of an invasive macrophyte.
Gribben, PE, Nielsen, S, Seymour, JR, Bradley, DJ, West, MN, Thomas, T
Scientific reports. 2017;(1):9845
Abstract
Invasive plants have extensive impacts on ecosystem function and biodiversity globally. Our inability to manage invasive species stems in part from a lack of understanding of the processes that control their successful establishment and spread. To date, studies have largely considered how above-ground processes control native/invasive plant interactions. Emerging research from terrestrial and wetland ecosystems demonstrates that below-ground processes under microbial control can determine the outcome of interactions between native and invasive plants. Whether sediment microbes modify the success of invasive macrophytes in marine ecosystems is untested, despite marine sediment microbes controlling many ecological processes (e.g. nutrient cycling) comparable to those in terrestrial ecosystems. We first show that sediment bacterial communities differ between the native seagrass Zostera capricorni and the invasive alga Caulerpa taxifolia and that those differences relate to functional changes in sulfur cycling between the macrophytes. Second, by experimentally manipulating the microbial communities we show that intact microbial communities in Z. capricorni sediments provide biotic resistance by reducing C. taxifolia fragment growth 119% compared to when they are inactive, and intact microbial communities in C. taxifolia sediments have positive feedbacks by increasing fragment growth 200%. Thus, similar to terrestrial ecosystems, microorganisms appear to indirectly control the success of invasive macrophytes in marine ecosystems.
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8.
Microaerophilic Fe(II)-Oxidizing Zetaproteobacteria Isolated from Low-Fe Marine Coastal Sediments: Physiology and Composition of Their Twisted Stalks.
Laufer, K, Nordhoff, M, Halama, M, Martinez, RE, Obst, M, Nowak, M, Stryhanyuk, H, Richnow, HH, Kappler, A
Applied and environmental microbiology. 2017;(8)
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Abstract
Microaerophilic Fe(II) oxidizers are commonly found in habitats containing elevated Fe(II) and low O2 concentrations and often produce characteristic Fe mineral structures, so-called twisted stalks or tubular sheaths. Isolates originating from freshwater habitats are all members of the Betaproteobacteria, while isolates from marine habitats belong almost exclusively to the Zetaproteobacteria So far, only a few isolates of marine microaerophilic Fe(II) oxidizers have been described, all of which are obligate microaerophilic Fe(II) oxidizers and have been thought to be restricted to Fe-rich systems. Here, we present two new isolates of marine microaerophilic Fe(II)-oxidizing Zetaproteobacteria that originate from typical coastal marine sediments containing only low Fe concentrations (2 to 11 mg of total Fe/g of sediment [dry weight]; 70 to 100 μM dissolved Fe2+ in the porewater). The two novel Zetaproteobacteria share characteristic physiological properties of the Zetaproteobacteria group, even though they come from low-Fe environments: the isolates are obligate microaerophilic Fe(II) oxidizers and, like most isolated Zetaproteobacteria, they produce twisted stalks. We found a low organic carbon content in the stalks (∼0.3 wt%), with mostly polysaccharides and saturated aliphatic chains (most likely lipids). The Fe minerals in the stalks were identified as lepidocrocite and possibly ferrihydrite. Immobilization experiments with Ni2+ showed that the stalks can function as a sink for trace metals. Our findings show that obligate microaerophilic Fe(II) oxidizers belonging to the Zetaproteobacteria group are not restricted to Fe-rich environments but can also be found in low-Fe marine environments, which increases their overall importance for the global biogeochemical Fe cycle.IMPORTANCE So far, only a few isolates of benthic marine microaerophilic Fe(II) oxidizers belonging to the Zetaproteobacteria exist, and most isolates were obtained from habitats containing elevated Fe concentrations. Consequently, it was thought that these microorganisms are important mainly in habitats with high Fe concentrations. The two novel isolates of Zetaproteobacteria that are presented in the present study were isolated from typical coastal marine sediments that do not contain elevated Fe concentrations. This increases the knowledge about possible habitats in which Zetaproteobacteria can exist. Furthermore, we show that the physiology and the typical organo-mineral structures (twisted stalks) that are produced by the isolates do not notably differ from the physiology and the cell-mineral structures of isolates from environments with high Fe concentrations. We also showed that the organo-mineral structures can function as a sink for trace metals.
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9.
Responses of Biogeochemical Characteristics and Enzyme Activities in Sediment to Climate Warming under a Simulation Experiment in Geographically Isolated Wetlands of the Hulunbuir Grassland, China.
Han, L, Su, D, Lv, S, Luo, Y, Li, X, Jiao, J, Diao, Z, Bu, H
International journal of environmental research and public health. 2017;(9)
Abstract
Climate warming generates a tremendous threat to the stability of geographically-isolated wetland (GIW) ecosystems and changes the type of evaporation and atmospheric precipitation in a region. The intrinsic balance of biogeochemical processes and enzyme activity in GIWs may be altered as well. In this paper, we sampled three types of GIWs exhibiting different kinds of flooding periods. With the participation of real-time temperature regulation measures, we assembled a computer-mediated wetland warming micro-system in June 2016 to simulate climate situation of ambient temperature (control group) and two experimental temperature differences (+2.5 °C and +5.0 °C) following a scientific climate change circumstance based on daily and monthly temperature monitoring at a two-minutes scale. Our results demonstrate that the contents of the total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) in the warmed showed, roughly, a balance or a slight decrease than the control treatment. Warming obstructed the natural subsidence of sediment, but reinforced the character of the ecological source, and reduced the activity of urease (URE), but promoted the activity of alkaline phosphatase (AKP) and sucrase (SUC). Redundancy analysis showed that sucrase, urease, available phosphorus (AP), and pH were the major correlating factors under warming conditions in our research scope. Total organic carbon, total nitrogen, sucrase, catalase (CAT), and alkaline phosphatase were the principal reference factors to reflect the ambient temperature variations. Nutrient compositions and enzyme activities in GIW ecosystems could be reconstructed under the warming influence.
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10.
Ancient plant DNA in lake sediments.
Parducci, L, Bennett, KD, Ficetola, GF, Alsos, IG, Suyama, Y, Wood, JR, Pedersen, MW
The New phytologist. 2017;(3):924-942
Abstract
Contents 924 I. 925 II. 925 III. 927 IV. 929 V. 930 VI. 930 VII. 931 VIII. 933 IX. 935 X. 936 XI. 938 938 References 938 SUMMARY Recent advances in sequencing technologies now permit the analyses of plant DNA from fossil samples (ancient plant DNA, plant aDNA), and thus enable the molecular reconstruction of palaeofloras. Hitherto, ancient frozen soils have proved excellent in preserving DNA molecules, and have thus been the most commonly used source of plant aDNA. However, DNA from soil mainly represents taxa growing a few metres from the sampling point. Lakes have larger catchment areas and recent studies have suggested that plant aDNA from lake sediments is a more powerful tool for palaeofloristic reconstruction. Furthermore, lakes can be found globally in nearly all environments, and are therefore not limited to perennially frozen areas. Here, we review the latest approaches and methods for the study of plant aDNA from lake sediments and discuss the progress made up to the present. We argue that aDNA analyses add new and additional perspectives for the study of ancient plant populations and, in time, will provide higher taxonomic resolution and more precise estimation of abundance. Despite this, key questions and challenges remain for such plant aDNA studies. Finally, we provide guidelines on technical issues, including lake selection, and we suggest directions for future research on plant aDNA studies in lake sediments.