Effects of Cyclodextrins on Dodecane Biodegradation

Bioremediation of non-chlorinated hydrocarbon-polluted soils is mainly affectedby low bioavailability, due to hydrophobicity of these xenobiotics. In fact, severalmicroorganisms can use hydrocarbons as energy and carbon sources, but theirdegradative activity takes place into the aqueous phase of the soil, where just tracesof hydrocarbons are found because of their low water solubility. So, natural attenuationusually occurs in hydrocarbon-polluted soils, but this process is very slow. It has alreadybeen demonstrated that cyclodextrins increase hydrocarbon solubility and bioavailabilityand accelerate their biodegradation. In this work it was investigated if their efficacy onbiodegradation of a model hydrocarbon (dodecane) is affected by the kind (,-, - and hydroxypropyl--cyclodextrin) and the concentrationof cyclodextrin and by environmental factors such as temperature and composition ofthe microbial indigenous population. The results obtained show that all the testedfactors influence the biodegradation kinetics. The best results were obtained with-cyclodextrin at a concentration near to its water solubility limit; moreover,biodegradation rate increases with temperature and different microbial strains showdifferent degradative activity and metabolic behaviour.     

除臭微生物F468发酵工艺

针对除臭微生物F468的应用,通过单因素实验和正交优化方案,研究了其发酵工艺.结果表明:F468适宜的氮源是酵母膏和硫酸铵;适宜的碳源是淀粉、葡萄糖和蔗糖,最佳pH是6.5,最佳培养温度是28℃;优化后F468种子液体培养基为1%葡萄糖 1%蔗糖,0.35%酵母膏,0.15%(NH4)2SO4,0.075%KH2PO4,0.01%NaCl,0.03%MgSO4·7H2O,0.003?SO4·7H2O,0.005?Cl2·2H2O,0.002%CuSO4·5H2O.研究结果为F468的规模化生产提供了发酵参数.     

一种硫酸盐还原菌的亚硫酸盐还原酶基因(dsrA)的克隆和序列分析

硫酸盐还原菌是一类具有重要生态学意义的微生物，从一种具有还原六价金属铬能力的复合硫酸盐还原菌SRBⅢ中克降了它的亚硫酸盐还原酶A亚基的完整基因，该序列带有亚硫酸盐还原酶-亚硝酸盐还原酶中保守的CX5CXNCX3C的序列，与巳报道的同类基因相比，该基因与脱硫脱硫弧菌（Essex6株）的异化型硫酸盐还原菌最为接近，核苷酸序列的同一性为89%，氨基酸序列的同一性约为94%。     

Evaluation of bacterial detachment rates in porous media

The ability of published biomass detachment rate expressions to describe experimental data obtained from porous media reactors usingPseudomonas aeruginosa grown aerobically on glucose was evaluated. A first-order rate expression on attached biomass concentration best reflected effluent substrate concentration for combined data sets. Detachment rate coefficientk _d1 was dependent on initial substrate concentration. Simulation of porous media reactor experiments indicated that responses using higher influent substrate concentrations possessed greater sensitivity to variations ink _d1. Simulations of field bioremediation systems suggest the use of accurate biofilm development kinetics is important in the prediction of well bore biofouling.     

Managed bioremediation of soil contaminated with crude oil soil chemistry and microbial ecology three years later

Analysis of samples taken from three experimental soil lysimeters demonstrated marked long-term effects of managed bioremediation on soil chemistry and on bacterial and fungal communities 3 yr after the application of crude oil or crude oil and fertilizer. The lysimeters were originally used to evaluate the short-term effectiveness of managed (application of fertilizer and water, one lysimeter) vs unmanaged bioremediation (one lysimeter) of Michigan Silurian crude oil compared to one uncontaminated control lysimeter. Three years following the original experiment, five 2-ft-long soil cores were extracted from each lysimeter, each divided into three sections, and the like sections mixed together to form composited soil samples. All subsequent chemical and microbiological analyses were performed on these nine composited samples. Substantial variation was found among the lysimeters for certain soil chemical characteristics (% moisture, pH, total Kjeldahl nitrogen [TKN], ammonia nitrogen [NH₄-N], phosphate phosphorous [PO₄-P], and sulfate [SO₄ ⁻²]). The managed lysimeter had 10% the level of total petroleum hydrocarbons (TPH-IR) found in the unmanaged lysimeter. Assessment of the microbial community was performed for heterotropic bacteria, fungi, and aromatic hydrocarbon-degrading bacteria (toluene, naphthalene, and phenanthrene) by dilution onto solid media. There was little difference in the number of heterotrophic bacteria, in contrast to counts of fungi, which were markedly higher in the contaminated lysimeters. Hydrocarbon-degrading bacteria were elevated in both oil-contaminated lysimeters. In terms of particular hydrocarbons as substrates, phenanthrene degraders were greater in number than naphthalene degraders, which outnumbered toluene degraders. Levels of sulfate-reducing bacteria seem to have been stimulated by hydrocarbon degradation.     

气相色谱/电感耦合等离子体质谱测定植物中挥发性硒化合物

Severalinstrumentalmethodscanbeusedforthedetectionanddeterminationofvolatileselenium(Se)andsulfur (S)compounds .Theserelyprimari lyongaschromatography (GC)forseparationanddifferentdetectiontechniques ,includingatomice missiondetection (AED ) ,massspectrom…     

广西元宝山矿区重金属空间分布特征

【目的】对广西元宝山矿区的重金属污染情况和分布特征进行评价。【方法】对矿区水体、土壤、植物的重金属含量进行测试分析和评价。【结果】元宝山矿区的水体重金属污染元素主要为铁、铝、锌、镍、钴、镉、锰,污染源为矿坑排水,超过Ⅳ类标准的倍数分别为5.5倍、22.5倍、4.7倍、10.8倍、11.9倍、9.9倍、6.1倍。元宝山矿区的土壤重金属污染元素为砷、镉、铜、镍、铅、锌,含量超标数倍至数百倍不等。【结论】元宝山矿区重金属的污染情况与污染源距离相关,大多数重金属浓度随与污染源距离的增加而减小,其中在距污染源5～8 km处减少最多。五节芒Miscanthus floridulus (Labill.) Warb.ex Schum.et Laut.可作为污染区的先锋修复物种。     

Biosorption and desorption of copper (II) ions by Bacillus sp.

Batch biosorption experiments were conducted to investigate the removal of Cu²⁺ ions from aqueous solutions by a series of bacterial strains isolated from a local activated sludge process. The characteristics of 12 isolates were identified and examined for their ability to bind Cu²⁺ ions from aqueous solution. Among the isolates, two species exhibited biosorption capacity >40 mg of Cu/g of dry cell. Isotherms for the biosorption of copper on bacterial cells were developed and compared, and the equilibrium data fitted well to the Langmuir and Freundlich isotherm models. The biosorption of copper increased significantly with increasing pH from 2.0 to 6.0 regardless of the species. More than 90% of copper sorbed on the cells of Bacillus sp. could be recovered by washing with 0.1 M HNO₃ for 5 min. The performance of two different desorption processes was also tested and compared. The results show that five biosorption and desorption cycles are a better operation process than five successive biosorptions followed by one desorption to remove and recover copper from aqueous solution. The biosorbent could be used for at least five biosorptions and desorption cycles without loss of copper removal capacity. It can be concluded that the activated sludge or sludge-isolated bacteria could be a potential biosorbent for copper removal.     

广西龙江镉污染事件及反思

2012年年初的广西龙江镉污染事件受到人们极大的关注。在分析这次镉污染事件来龙去脉的基础上,对金属镉的相关知识、镉环境污染的现状和治理方法进行了介绍,提醒人们要高度重视重金属的环境污染,提高环保意识。     

污染土壤原位生物修复理论模型

本文针对污染土壤原位生物修复技术,建立了土壤中气-液两相流动、污染物扩散与生物降解的理论模型,并进行了计算和分析,讨论了渗透廊的加入对液体饱和度的分布、液膜厚度分布以及污染物浓度分布的影响。结果表明:调节渗透廊内液面高度和渗透廊底面厚度,可以控制土壤中液体饱和度及液膜厚度的分布,且对污染物降解效率具有明显的影响。