共查询到20条相似文献,搜索用时 46 毫秒
1.
Shengnan SHI Fang MA Tieheng SUN Ang LI Jiti ZHOU Yuanyuan QU 《Frontiers of Environmental Science & Engineering》2014,8(4):539-546
A mulfistep conversion system composed of phenol hydroxylase (PHrND) and 2,3-dihydroxy-biphenyl 1,2-dioxygenase (BphCLA_4) was used to synthesize methylcatechols and semialdehydes from o- and m-cresol for the first time. Docking studies displayed by PyMOL predicted that cresols and methylcatechols could be theoretically transformed by this multistep conversion system~ High performance liquid chromatography mass spectrometry (HPLC-MS) analysis also indicated that the products formed from multistep conversion were the corresponding 3-methylcatechol, 4-methylcatechol, 2- hydroxy-3-methyl-6-oxohexa-2,4-dienoic acid (2- hydroxy-3-methyl-ODA) and 2-hydroxy-5-methyl-6-oxo- hexa-2,4-dienoic acid (2-hydroxy-5-methyl-ODA). The optimal cell concentrations of the recombinant E. coli strain BL21 (DE3) expressing phenol hydroxylase (PHrND) and 2,3-dihydroxy-biphenyl 1,2-dioxygenase (BphCLA_4) and pH for the multistep conversion of o- and m-cresol were 4.0 (g-L-1 cell dry weight) and pH 8.0, respectively. For the first step conversion, the formation rate of 3- methylcatechol (0.29μmol·L-1·min-1·mg-1cell dry weight) from o-cresol was similarly with that ofmethylca- techols (0.28 μmol·L-1·min-1·mg-1 cell dry weight) from m-cresol by strain PHrND. For the second step conversion, strain BphCLA_4 showed higher formation rate (0.83 μmol·L-1·min-1·mg-1 cell dry weight) for 2-hydroxy-3-methyl- ODA and 2-hydroxy-5-methyl-ODA from m-cresol, which was 1.1-fold higher than that for 2-hydroxy-3-methyl- ODA (0.77 μmol·L-1·min-1·mg-1. mglcell dry weight) from ocresol. The present study suggested the potential application of the multistep conversion system for the production of chemical synthons and high-value products. 相似文献
2.
Dissolved iodine in sea water, about 60 μg L-1, usually exists in equal proportions as iodate and iodide ions. For their determination several techniques have been proposed (Riley, 1975); among them the volumetric one which depends upon the release of elementary iodine by the addition of acid and iodide ions to the iodate present in the sample. The liberated iodine is titrated with thiosulphate the equivalence point being detected photometrically (Matthews and Riley, 1970; Wong and Brewer, 1974) or it can also be reduced with an excess of thiosulphate and the residual thiosulphate back-titrated with iodate amperometrically (Barkley and Thompson, 1960; Truesdale and Spencer, 1974; Tsonkova and Kulev, 1981). To titrate total iodine in the sample the iodide must be previously oxidized to iodate with bromine (Barkley and Thompson, 1960; Tsonkova and Kulev, 1981) or permanganate (Schnepfe, 1972). In the amperometric procedure Truesdale and Spencer (1974) observed that platinum electrodes often do not respond reliably. 相似文献
3.
Yun FANG Meiying XU Xingjuan CHEN Guoping SUN Jun GUO Weimin WU Xueduan LIU 《Frontiers of Environmental Science & Engineering》2015,9(3):444
Extraction of high-quality microbial DNA from contaminated environmental samples is an essential step in microbial ecological study. Based on previously published methods for soil and sediment samples, a modified pretreatment method was developed for extracting microbial DNA from heavily contaminated river sediment samples via selection of optimal pretreatment parameters (i.e., reagent solution, reaction duration, and temperature). The pretreatment procedure involves washing the river sediment sample for three times with a solution containing 0.1 mol·L-1 ethylene diamine tetraacetic acid (EDTA), 0.1 mol·L-1 Tris (pH 8.0), 1.5 mol·L-1 NaCl, 0.1 mol·L-1 NaH2PO4, and Na2HPO4 at 65°C with 180 r·min-1 for 15 min to remove humic materials and heavy metals prior to the employment of standard DNA extraction procedures. We compared the results of standard procedure DNA extraction following pretreatment, without pretreatment, and with using a commercial PowerSoilTM DNA Isolation Kit. The results indicated that the pretreatment significantly improved the DNA quality based on DNA yield, DNA fragment length, and determination of prokaryotic diversity. Prokaryotic diversity exhibited in the DNA with the pretreatment was also considerably higher than that extracted with the PowerSoilTM DNA Isolation Kit only. The pretreatment method worked well even with a small amount of sediment sample (0.25 g or even lower). The method provides a novel, simple, cost-effective tool for DNA extraction for microbial community analysis in environmental monitoring and remediation processes. 相似文献
4.
E. J. Perkins 《Chemistry and Ecology》1983,1(4):311-330
The litter content of littoral and sublittoral sediments from the Solway Firth, Firth of Clyde and the coast of Devon was measured by passing samples of sediment through 500 and 1000 μm sieves and hand picking of the residues. The litter present in samples from each station was shown to be very variable both in amount and in the quality of the component fractions. No clear relationship with silt content and type of shore emerged. 相似文献
5.
R. Danovaro A. Pusceddu A. Covazzi Harriague D. Marrale A. Dell'sanno M. Petrillo G. Albertelli N. Della Croce 《Chemistry and Ecology》1999,16(1):7-30
The structure of the benthic microbial loop was studied in order to understand heterotrophic pathways in the suboxic sediments of the Rapallo Harbour in autumn, 1996. Sediments were characterized by the large accumulation of organic detritus (17.2 - 21.4 μg chloroplastic pigment equivalents (CPE)g-1; carbohydrates and proteins: 7.8-16.7 and 6.7-7.5 mg g-1). Due to the high organic load, benthic bacteria and protozoa displayed extremely high densities (1.4 × 109 cells g-1 and 26.9 × 105 cells g-1). Meiofauna, protozoa and bacteria showed an approximate biomass ratio of 1:2:20. the presence of large amounts of organic matter appeared to determine a shift of the benthic size structure toward the increasing dominance of the smaller components of the benthic food webs. These data indicate that the sediments of the Rapallo Harbour were dominated by microbial biomasses to a larger extent than in non-food limited environments, characterized by a lower organic contamination. On the results presented in this study, the microbial dominance in highly organic enriched sediments can be explained with: (1) a reduction of the top-down control and grazing pressure of meio- and macrofauna on the microbial components; (2) the opportunistic composition and high metabolic activity of the microbial components. 相似文献
6.
Mary Beth LEIGH Wei-Min WU Erick CARDENAS Ondrej UHLIK Sue CARROLL Terry GENTRY Terence L. MARSH Jizhong ZHOU Philip JARDINE Craig S. CRIDDLE James M. TIEDJE 《Frontiers of Environmental Science & Engineering》2015,9(3):453
Stable isotope probing (SIP) was used to identify microbes stimulated by ethanol addition in microcosms containing two sediments collected from the bioremediation test zone at the US Department of Energy Oak Ridge site, TN, USA. One sample was highly bioreduced with ethanol while another was less reduced. Microcosms with the respective sediments were amended with 13C labeled ethanol and incubated for 7 days for SIP. Ethanol was rapidly converted to acetate within 24 h accompanied with the reduction of nitrate and sulfate. The accumulation of acetate persisted beyond the 7 d period. Aqueous U did not decline in the microcosm with the reduced sediment due to desorption of U but continuously declined in the less reduced sample. Microbial growth and concomitant 13C-DNA production was detected when ethanol was exhausted and abundant acetate had accumulated in both microcosms. This coincided with U(VI) reduction in the less reduced sample. 13C originating from ethanol was ultimately utilized for growth, either directly or indirectly, by the dominant microbial community members within 7 days of incubation. The microbial community was comprised predominantly of known denitrifiers, sulfate-reducing bacteria and iron (III) reducing bacteria including Desulfovibrio, Sphingomonas, Ferribacterium, Rhodanobacter, Geothrix, Thiobacillus and others, including the known U(VI)-reducing bacteria Acidovorax, Anaeromyxobacter, Desulfovibrio, Geobacter and Desulfosporosinus. The findings suggest that ethanol biostimulates the U(VI)-reducing microbial community by first serving as an electron donor for nitrate, sulfate, iron (III) and U(VI) reduction, and acetate which then functions as electron donor for U(VI) reduction and carbon source for microbial growth. 相似文献
7.
Kun Li Tingming Ye Wang Zhang Jianfeng Peng Yaohui Bai Weixiao Qi Huijuan Liu 《Frontiers of Environmental Science & Engineering》2022,16(2):17
8.
Heavy-metal distribution and risk assessment of sediment and fish from El-Mex Bay, Alexandria, Egypt
Heavy metals are increasingly being released into natural waters from geological and anthropogenic sources. The distribution of several heavy metals (Cr, Cu, Cd, Pb, Zn, and Hg) was investigated in muscle, gill, and liver in two different fish species seasonally collected in El-Mex Bay (autumn 2004-summer 2005). In order to evaluate the pollution status of the Bay, the concentrations of the selected metals in the labile and total fractions were analysed in sediment samples collected from eight sites in El-Mex Bay during autumn 2004. Also, the Index of Geoaccumulation (Igeo) for the sediment was estimated. The total and labile fractions of the selected metals in sediment samples were 15.2 and 62.8 μg g-1 dw for Cu, 1.8 and 5.0 μg g-1 dw for Cd, 79.1 and 130.3 μg g-1 dw for Zn, 0.2 and 1.2 μg g-1 dw for Hg, 35.8 and 93.0 μg g-1 dw for Pb, and 13.9 and 31.0 μg g-1 dw for Cr. The concentrations of all metals were lower in flesh than those recorded in liver and gill due to their physiological roles. The metal pollution index for fish was calculated. Health hazard calculations for the contaminated sediments and fish consumption were calculated to evaluate the effect of pollution on health. 相似文献
9.
Xingguo Guo Qiuying Wang Ting Xu Kajia Wei Mengxi Yin Peng Liang Xia Huang Xiaoyuan Zhang 《Frontiers of Environmental Science & Engineering》2020,14(2):30
10.
This study was to assess the metal contamination in oyster tissue grown in the Ann-ping mariculture ground in Taiwan. the information generated from this work also revealed general metal pollution problem for Taiwan's oyster farmers. Oysters, Crassostrea gigas, and surficial sediments collected from ten locations in Ann-ping mariculture ground in Taiwan for metals concentration (Cu, Zn, Pd, Cd, Fe and Mn) were performed. Analytical results indicated that the yearly averaged oyster copper concentrations (μg g-1, wet weight) in oyster soft parts from Ann-ping increased from 21.3±4.1 in 1993; 24.1±6.8 in 1994; 36.8±11.9 in 1995 to 43.9±23.1 μg g-1, wet weight, in the 1996 raising season. the mean oyster copper concentration reached a level of 50 μg g-1, wet weight, in December 1996. This increasing trend of metal concentration in oyster tissue indicates a potential pollution source which may pose a potential disaster as green oyster incidence, which occurred on the Charting coast in 1986, in Taiwan. Sediment samples in Ann-ping mariculture ground were also collected and examined. the seasonal variation of the copper concentration in surficial sediment from Ann-ping did not show an increasing trend as observed in oyster tissue. 相似文献
11.
Yuanyuan Luo Yangyang Zhang Mengfan Lang Xuetao Guo Tianjiao Xia Tiecheng Wang Hanzhong Jia Lingyan Zhu 《Frontiers of Environmental Science & Engineering》2021,15(5):96
12.
Polychaetes belonging to the genus Capitella are often present in high numbers in organic-rich sediments polluted with, e.g., oil components, and Capitella spp. may have a great impact on the biogeochemistry of these sediments. We examined the influence of Capitella sp. I on microbial activity in an organic-rich marine sediment contaminated with the polycyclic aromatic hydrocarbon, fluoranthene.
Capitella sp. I were added to microcosms (10 000 ind m−2) and the impact of a pulse-sedimentation of fluoranthene-contaminated sediment (3 mm layer) was studied for a period of 12
d after sedimentation. The sediment oxygen uptake and total sediment metabolism (TCO2 production) increased in cores with worms (71 to 131%), whereas the anaerobic activity, measured as sulfate reduction rate
12 d after sedimentation, was lower compared to cores without worms. The effect of fluoranthene on sulfate reduction was most
pronounced in the presence of worms, with a 34% reduction versus 16% in cores without worms. The reduced sulfur pools in cores
with worms were smaller than in cores without worms, suggesting that the reduced anaerobic activity was caused by increased
oxidation of the sediment, which may favor O2 and other electron-acceptors (e.g. NO3
−, Fe3+, Mn4+) in organic matter decomposition. The sediment oxygen uptake and TCO2 production did not show significant changes due to fluoranthene treatment, indicating that these parameters were either less
sensitive to fluoranthene stress or recovered more rapidly (i.e. within 48 h) than sulfate reduction rates. Bioturbation by
Capitella sp. I altered the depth profile of fluoranthene such that fluoranthene was found in deeper sediment layers (down to 2 cm)
where diffusional loss and microbial breakdown probably are reduced relative to surface layers. In cores without worms, fluoranthene
was found down to 1 cm, with 75% remaining in the upper 5 mm.
Received: 5 December 1996 / Accepted: 11 February 1997 相似文献
13.
Yuhan Zheng Zhiguo Su Tianjiao Dai Feifei Li Bei Huang Qinglin Mu Chuanping Feng Donghui Wen 《Frontiers of Environmental Science & Engineering》2019,13(6):90
14.
Atef A. Moussa Mohamed A. El-sabrouti Osman A. El-rayis Khalil M. Kh 《Chemistry and Ecology》1994,9(1):31-40
Lake Edku is one of the Nile Delta shallow brackish water coastal lagoons with communications with the southeastern Mediterranean.
Sediment samples were recovered from the top 10 cm of the lake bottom to study principally their total, inorganic and organic phosphorus. Related sediment parameters such as particle size, organic carbon, carbonate and iron contents were also studied in detail.
It is shown that the lake sediments are generally a sand-silt-clay mud enriched with carbonate (11.4-42%), organic carbon (0.9-11.4%) and iron (1.6-5.6%).
The total phosphorus content in these sediments is 503-1329 μg/g, inorganic phosphorus, 468-954 μg/g and organic phosphorus, 35-526 μg/g. 相似文献
Sediment samples were recovered from the top 10 cm of the lake bottom to study principally their total, inorganic and organic phosphorus. Related sediment parameters such as particle size, organic carbon, carbonate and iron contents were also studied in detail.
It is shown that the lake sediments are generally a sand-silt-clay mud enriched with carbonate (11.4-42%), organic carbon (0.9-11.4%) and iron (1.6-5.6%).
The total phosphorus content in these sediments is 503-1329 μg/g, inorganic phosphorus, 468-954 μg/g and organic phosphorus, 35-526 μg/g. 相似文献
15.
Sediment microbial fuel cell with floating biocathode for organic removal and energy recovery 总被引:2,自引:2,他引:0
Aijie WANG Haoyi CHENG Nanqi REN Dan CUI Na LIN Weimin WU 《Frontiers of Environmental Science & Engineering》2012,6(4):569-574
A sediment microbial fuel cell (SMFC) with three dimensional floating biocathode (FBC) was developed for the electricity generation and biodegradation of sediment organic matter in order to avoid negative effect of dissolved oxygen (DO) depletion in aqueous environments on cathode performance and search cost-effective cathode materials. The biocathode was made from graphite granules with microbial attachment to replace platinum (Pt)-coated carbon paper cathode in a laboratory-scale SMFC (3 L in volume) filled with river sediment (organic content 49±4 g·kg-1 dry weight). After start-up of 10 days, the maximum power density of 1.00W·m-3 (based on anode volume) was achieved. The biocathode was better than carbon paper cathode catalyzed by Pt. The attached biofilm on cathode enhanced power generation significantly. The FBC enhanced SMFC performance further in the presence aeration. The SMFC was continuously operated for an over 120-day period. Power generation peaked within 24 days, declined gradually and stabilized at a level of 1/6 peak power output. At the end, the sediment organic matter content near the anode was removed by 29% and the total electricity generated was equal to 0.251 g of chemical oxygen demand (COD) removed. 相似文献
16.
We investigated the influence of the mineralogical composition of marine sediments on bacterial activity in experimental microcosms. Calcite and quartz were added to natural marine sediments and microbial response in terms of total bacterial abundance and biomass, β-D-glucosidase exo-enzymatic activity and bacterial incorporation of a radio-labelled (3H-leucine) substrate were investigated for a period of one month. We report here that after 15 days the mineralogical composition of the sediment (calcite vs. quartz) had an impact on bacterial abundance and activity (reduced for ca 15% and 56%, respectively). However, such impact was mitigated or even disappeared in high organic nutrient conditions. 相似文献
17.
Kun Li Min Yang Jianfeng Peng Ruiping Liu Tista Prasai Joshi Yaohui Bai Huijuan Liu 《Frontiers of Environmental Science & Engineering》2019,13(6):87
18.
Water samples were taken from 12 stations at El-Dikheila Harbour, El-Mex Bay, Western Harbour, Qayet Bey outfall, Eastern Harbour, El-Ibrahemiya, Gleem, Sidi Bishr and Mandara, during January, April, August and November 1995. the area lies between latitude 31˚ 8' and 31˚ 17' North and longitude 29˚ 47' and 30˚ East. the annual mean of chlorinity (11.69-20.5%0), pH (7.9-8.3), reactive phosphate (0.31-2.24 μM), nitrite (0.18-1.98 μM), oxidizable organic matter (1.97-8.95 mgO2 1-1), iodide (21.14-46.74 μg 1-1) and iodate (4.61-2.04 μg 1-1) were measured. Iodide content in water is three times higher than iodate. Iodide is positively correlated with chlorinity (r=0.65) and iodate (r=0.45), while it is negatively correlated with nitrite (r= -0.72), oxidizable organic matter (r= -0.55) and pH (r= -0.4). 相似文献
19.
Bin Liang Deyong Kong Mengyuan Qi Hui Yun Zhiling Li Ke Shi E Chen Alisa S. Vangnai Aijie Wang 《Frontiers of Environmental Science & Engineering》2019,13(6):84
20.
Sanjena Narayanasamydamodaran Jian e Zuo Haiteng Ren Nawnit Kumar 《Frontiers of Environmental Science & Engineering》2021,15(4):66