检索结果-南通市图书馆

Fossil bacteria in Xuanlong iron ore deposits of Hebei Province

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2004年第4期47卷 347-356页

作者： DAI Yongding, SONG Haiming & SHEN Jiying Institute of Geology and Geophysics, Chinese Academy of Sciences,Beijing 100029, China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

Discovered in Early Proterozoic Xuanlong iron ore deposits are six genera of fossil iron bacteria, i. e. sphere (coenobium of) rod-shaped (monomer) Naumanniella, ellipsoid elliptical Ochrobium,sphere spherical Siderocapsa and chain spherical Siderococcus, chain rod-shaped Leptothrix and Lieskeella, and six genera of fossil blue bacteria, namely sphere spherical Gloeocapsa, Synechocystis and Globobacter, chain spherical Anabaena and Nostoc, and con-strictive septate tubular Nodularia. The biomineralized monomers and coenobia of the two cate-gories of bacteria, together with hematite plates made up the bacteria pelletal, bacteria silky, bacteria fibrous and clasty bacteria pelletal textural lamina. The bacteria pelletal laminae com-bined with other bacteria laminae to make up oncolite, stromatolite and laminate. The precipita-tion of iron oxide was accelerated due to iron and blue bacteria cohabiting on microbial film or mat. The Xuanlong iron ore deposits are microbial binding ore deposits of ocean source.

关键词： iron and blue bacteria, bacteria textural lamina, microbial ore deposits, Late Early Proterozoic.

Vertical distribution of phosphorus and P-dissolving/ decomposing bacteria in the sediment of Guanting reservoir

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第Z2期48卷 285-294页

作者： LI Cui, YUAN Hongli & HUANG Huaizeng College of Biological Sciences, Key Laboratory of Agro-Microbial Resource and Application, Ministry of Agriculture, China Agricultural University, Beijing 100094, China National Research Center of Geoanalysis, Beijing 100037, China College of Biological Sciences Key Laboratory of Agro-Microbial Resource and Application Ministry of Agriculture China Agricultural University Beijing 100094 China National Research Center of Geoanalysis Beijing 100037 China

In this study, we determined pH, phosphorus content and the number of P-dis- solving/decomposing bacteria in relation to the depth in the sediment of Guanting reservoir in Beijing. The pH value was slightly increased from 8.0 in the surface to 8.5 in the bottle (69 cm in depth) of sediment. The highest P content, 1269 mg/kg, was detected in the 35 cm layer, followed by the 5 cm (993 mg/kg) and 69 cm (580 mg/kg) layers. The number of inorganic P-dissolving bacteria varied from 6(102 to 8(104 and the organic P-discomposing bacteria were from 1.9(103 to 6.3(104 per gram sediment in different depths, which were counted under 28℃ and 20℃ ( pH7.5 and 8.5. The number of P-dissolving/discomposing bacteria was directly correlated to the P content in each layer of sediments. The analysis of P-dissolving/decomposing ability of bacteria showed that some of these bacteria were also capable of accumulating P intracellularly. The intracellular P-accumulation was more efficient at lower temperature; in contrast, the activity of P-dissolving/decomposing was stronger at higher temperature. So the content of dissolved P in water body, or quality of water, could be affected by the change of temperature via the regulation of bacterial activity. On the basis of 16S rDNA sequencing, the 13 efficient P-dis- solving/decomposing bacteria were identified as Bacillus spp., Bacterium sp., Microbacterium sp., Paenibacillus sp. and Pseudomonas sp.

关键词： Guanting reservoir, sediment, P-dissolving/decomposing bacteria, phosphorus cycling, eutrophication.

Study on the Development of Lactic Acid bacteria in Bread Dough Enriched with Zinc and Selenium

在线全文

学校读者我要写书评

暂无评论

Journal of Food Science and Engineering 2017年第10期7卷 497-504页

作者： Denka Zlateva Dana Stefanova Nadya Ninova-Nicolova Department of Commmodity Science Faculty of Economics University of Economics Varna 9000 Bulgaria LB Bulgaricum PLC Research & Development Center Sofia 1225 Bulgaria

The incorporation of lyophilized lactic acid bacteria in dough formulation is a current trend in bread making in order toachieve quality improvement and extension of shelf life of bread. Another major aspect for today＇s bread making industry is anincrease of the biological value of bread, by addition of mineral substances that are deficient in bread （such as zinc and selenium）.This is an effective approach to combat the existing mineral deficiency in population nutrition. The aim of the present study is toinvestigate the development of lactic acid bacteria in a medium enriched with zinc and selenium. It was found that the addition ofZnSO4-7H20 in an amount of 0.174 g/kg flour and Na2SeO3.5H20 in an amount of 880.28 μg/kg flour （alone and in combination） didnot inhibit the development of lactic acid bacteria used as starter cultures in bread dough formulation. It was found that the growth ofthe lactococcal component of the applied starters is dominant. The results reveal the possibility of obtaining bread with increasedbiological value and improved quality.

关键词： Bread dough, lactic acid bacteria, starter cultures, zinc, selenium.

Spectroscopic evidence for triplet excitation energy transfer among carotenoids in the LH2 complex from photosynthetic bacterium Rhodopseudomonas palustris

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2004年第1期47卷 80-90页

作者： FENG Juan, WANG Qian, ZHANG Xujia, HUANG Youguo, Al Xicheng, ZHANG Xingkang & ZHANG JianpingState Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing China National Laboratory of Biomacromolecules Institute of Biophysics Chinese Academy of Sciences Beijing China

The LH2 complex from Rhodopsudomonas (Rps.) palustris is unique in the heterogeneous carotenoid compositions. The dynamics of triplet excited state Carotenoids (3Car* has been investigated by means of sub-microsecond time-resolved absorption spectroscopy both at physiological temperature (295 K) and at cryogenic temperature (77K). Broad and asymmetric T n ←T 1 transient absorption was observed at room temperature following the photo-excitation of Car at 532 nm, which suggests the contribution from various carotenoid compositions having different numbers of conjugated C=C double bonds (Nc=c). The triplet absorption bands of different carotenoids, which superimposed at room temperature, could be clearly distinguished upon decreasing the temperature down to 77 K. At room temperature the shorter-wavelength side of the main Tn04T1 absorption band decayed rapidly to reach a spectral equilibration with a characteristic time constant of ∽1 μs, the same spectral dynamics, however, was not observed at 77 K. The aforementioned spectral dynamics can be explained in terms of the triplet-excitation transfer among heterogeneous carotenoid compositions. Global spectral analysis was applied to the time-resolved spectra at room temperature, which revealed two spectral components peaked at 545 and 565 nm, and assignable to the Tn04 T1 absorption of Cars with Nc=c=11 and Nc=c=13, respectively. Surprisingly, the decay time constant of a shorter-conjugated Car, i.e. 0.72 ?s (aerobic) and 1.36 ?s (anaerobic), is smaller than that of a longer-conjugated Car, i.e. 2.12 us (aerobic) and 3.75 ?s (anaerobic), which is contradictory to the general rule of carotenoids and relative polyenes. The results are explained in terms of triplet-excitation transfer among different types of Cars. It is postulated that two Cars with different conjugation lengths coexist in an α, β-subunit in the LH2 complex.

关键词： purple photosynthetic bacteria, carotenoid, excited-state, time-resolved spectroscopy.

Experimental study on reduction of U (Ⅵ) by an anaerobic bacterium, Shewanella putrefaciens: Application to sandstone-hosted interlayer oxidation-zone type uranium deposits, China

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2005年第3期48卷 346-352页

作者： L.L.Barton Department of Biology University of New Mexico Albuquerque NM 87131-1116USA

An experimental study on reduction of U (VI) by anaerobic bacteria, Shewanella putrefaciens, is first reported here in China. The experimental conditions were: 35℃ and pH = 7.0—7.4, corresponding to a physicochemical environments in which the sandstone-hosted in- terlayer oxidation-zone type uranium deposit formed in Northwest China’s Xinjiang. bacteria adopted in the present experiment, Shewanella putrefaciens, occur extensively in natural envi- ronment. Our study shows that nano-crystal precipitates of uraninite quickly occurred on the surface of the cells within one week. It was found that the pitchblende was characterized by a random arrangement of uraninite nanocrystals (2—4 nm) in it, significantly different from natural pitchblende in which uraninite nanocrystals are arranged in order. Finally, a possible mechanism of uranium biomineralization by microorganisms in the deposits is discussed. Our investigation may supply a technical train of thoughts for bioremediation of nuclear-contaminated water envi- ronments and for underground dissolving extraction of the sandstone-hosted uranium ores.

关键词： anaerobic bacteria, reduction, pitchblende, sandstone-hosted uranium deposit, experimental study.

Applicability and Limits of Bioremediation of Contaminated Groundwater by Organic Compounds

在线全文

学校读者我要写书评

暂无评论

Global Geology 2001年第1期6卷 97-104页

作者： Taboure Aboubacar and Lin Xueyu (Jilin university. Changchun, 130026 P. R. China) Jilin University Changchun. 130026 P.R. China

This paper gives in some ways a broad look at the Biorcmediation Technology in the treatment of polluted groundwater. Environmentalists and Hydrologeologists around the world, especially in the developed countries welcomed this revolutionizing technique at a moment when other methods were beconling rather expensive and sources of secondary and more challenging pollution problems across sole fresh groundwater. Bioremediation of contaminated groundwater is based on the use of bacteria which breakdown organic matters to more stable forms, which will not create nuisance or give off foul odors. The Applicability of this technology at a specific site lies in the understanding of the site’s hydrogeologic, physio- chemical backgrounds and the knowledge of the properties of the designated bacteria colonies, which would likely stabilize the contaminants. These are key points, which determine the success of the all process. Only, by complying with all those mea- surcs, Biorcmediation can meet all the expectations.

关键词： bioremediation, bacteria, pollutant, groundwater.

Identification of a denitrifying bacterium and verification of its anaerobic ammonium oxidation ability

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2006年第5期49卷 460-466页

作者： HU Baolan ZHENG Ping LI Jinye XU Xiangyang JIN Rencun Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Environmental Engineering Zhejiang University Hangzhou 310029 China

A strain D3 of denitrifying bacterium was isolated from an anammox reactor,and identi-fied as Pseudomonas mendocina based on the morphological and physiological assay,Vitek test,Biolog test,(G+C) mol% content,and 16S rDNA phylogenetic *** a typical denitrifying bac-terium,strain D3 achieved the maximal nitrate reduction rate of 26.2 mg/(L·d) at the nitrate concen-tration of 88.5 mg N/*** optimal pH and growth temperature were 7.84 and 34.9℃,*** D3 was able to oxidize ammonia under anaerobic *** maximum nitrate and ammo-nium utilization rates were 6.37 mg/(L·d) and 3.34 mg/(L·d) ,respectively,and the consumption ratio of ammonia to nitrate was 1:*** microscopic observation revealed peculiar cell inclusions in strain *** of its relation to anammox activity,strain D3 was presumed to be *** present investigation proved that denitrifying bacteria have the anammox ability,and the results have engorged the range of anammox populations.

关键词： Pseudomonas mendocina, denitrifying bacteria, anammox bacteria, anammoxosome.