Mineral nutrient imbalance, DNA lesion and DNA-protein crosslink involved in growth retardation of Vicia faba L. seedlings exposed to lanthanum ions

Effects of mineral nutrient imbalance, DNA lesion and DNA-protein crosslink on growth of Vicia faba L. seedlings hydroponically cultivated in concentrations of extraneous lanthanum (La) for 20 days were investigated in the present experiment. The results showed that contents of La, Cu or K elements in roots generally changed synchronously with those in leaves, while Ca, Fe, Zn, Mg, Mn or P in the roots altered inversely to those in the leaves. Thus, the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves. DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis (SCGE) and sodium dodecyl sulfate/potassium (SDS/K⁺) precipitation methods, respectively. The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks (DPCs) in the seedlings. These results suggested that mineral nutrient imbalance, DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings, which may help to understand the mechanisms of rare earth elements (REEs) on plant growth.     

Influence and mechanism of N-(3-oxooxtanoyl)-L-homoserine lactone (C8-oxo-HSL) on biofilm behaviors at early stage

N-acyl-homoserines quenching, enzymatic quenching of bacterial quorum sensing, has recently applied to mitigate biofilm in membrane bioreactor. However, the effect of AHLs on the behavior of biofilm formation is still sparse. In this study, Pseudomonas aeruginosa biofilm was formed on ultra-filtration membrane under a series of N-(3-oxooxtanoyl)-L-homoserine lactone (C₈-oxo-HSL) concentrations. Diffusing C₈-oxo-HSL increased the growth rate of cells on biofilm where the concentration of C₈-oxo-HSL was over 10^-7 g/L. The C₈-oxo-HSL gradient had no observable influence on cell density and extracellular polymeric substances of biofilm with over 10^-7 g/L C₈-oxo-HSL. Surprisingly, 10^-11-10^-8 g/L of C₈-oxo-HSL had no effect on cell growth in liquid culture. The cell analysis demonstrated that the quorum sensing system might enhance the growth of neighboring cells in contact with surfaces into biofilm and may influence the structure and organization of biofilm.     

流化床微生物燃料电池基质降解动力学研究

研究了在30℃左右条件下,流化床微生物燃料电池(FBMFC)处理有机废水的基质降解动力学。在空气阴极、单室、无膜液固流化床微生物燃料电池中,以污水和椰壳活性炭为液相和固相,通过实验考察不同水力停留时间的污水COD变化。选取Monod模型和简单动力学模型,通过合理的假设推导出流化床微生物燃料电池处理模拟有机废水时的基质降解动力学模型。将实验数据代入到理论推导得到的动力学模型中,进行线性拟合和对比分析,得到Monod模型和一级反应动力学模型表达式。结果表明流化床微生物燃料电池基质降解为一级反应;Monod模型表达式为:t/s0-st=4.769 7/st+15.885,一级动力学模型为:lnCA=-0.025 32t+8.109 15,理论推导模型与实验数据具有较好的吻合性。     

HPLC-ICPMS对环境样品中Cr(Ⅲ)和Cr(Ⅵ)分析研究

采用动态反应池(Dynamic Reaction Cell,DRC)消除环境样品中碳和氯对铬ICP-MS测定的干扰,实验结果表明O2比CH4能更加有效地消除基体干扰,52Cr更适宜作为铬形态分析的同位素。在优化的DRC条件下2.284μg/L、4.886μg/L和10.579μg/L 3个加标浓度下均具有理想的回收率。进一步采用Pecosphere C8分析柱(3×3),深入研究了流动相组成、pH值及流速对铬形态分离的影响,在1.0 mmol/L四丁基氢氧化铵(TBAH)+0.5 mmol/L乙二胺四乙酸二钠(EDTA)+1%甲醇流动相组成,pH 6.9和流速1.2 mL/min的色谱条件下可以得到最为理想的分离效果,在10～100μg/L标准浓度范围内,Cr(Ⅲ)和Cr(Ⅵ)的线性相关系数均大于0.999 7,建立的方法对Cr(Ⅲ)和Cr(Ⅵ)具有较好的重复性。最后尝试性地对模拟填埋场和地下水环境下市政污泥在脱水、干化和热解过程中铬形态的环境迁移性进行了研究,为更加准确评价铬元素对生态环境的潜在危害提供参考依据。     

可降解壬基酚的产电假单胞菌LQF-6的分离及其特性研究

从稳定运行以壬基酚为燃料的微生物燃料电池阳极生物膜分离到一株能以壬基酚为唯一碳源生长的产电菌LQF-6。对菌株LQF-6的形态和16S rDNA序列分析表明该菌为假单胞菌。LQF-6以壬基酚为唯一碳源,培养84 h壬基酚降解率为53.80%。差分脉冲伏安测定结果表明,LQF-6分别在-0.088 V和0.272 V出现两个氧化峰。菌株LQF-6接种至微生物燃料电池阳极室,以壬基酚为底物,铁氰化钾为阴极电子受体,外接电阻为1000Ω时,微生物燃料电池最大输出电压达0.17 V,电池最大功率密度为(58.51±2.24)m W/m²。     

外循环气升式反应器中光合细菌处理味精废水的研究

外循环气升式反应器（ＥＡＬＲ）中球形红假单胞菌处理味精废水,能生产单细胞蛋白。在连续供气、ＫＬａ为２４２ｈ＾－１,ＨＲＴ为１２ｈ,活性炭载体浓度为１０ｇ／Ｌ,进水ＢＯＤ５为２７５０ｍｇ／Ｌ条件下,废水ＢＯＤ５的去除率达到９２％。载体增加反应器内生物量２８％,ＳＣＰ产率系数Ｙ＝０．５９ｋｇ（ｃｅｌｌ）／（ｋｇ ＢＯＤ５·ｄ）,是无载体组的２倍。ＥＡＬＲ的生物负荷为１．６８ｋｇ ＢＯＤ５／（ｋｇ ＭＬ     

处理啤酒洗糟废水同时生产单细胞蛋白

用热带假丝酵母在 1.5L气升式内循环生物反应器中处理啤酒生产中的洗糟废水 ,同时生产热带假丝酵母 .探讨了 pH,温度及氮源对降解废水动力学的影响 .实验结果表明 ,用热带假丝酵母既可以有效地降解洗糟废水中的 COD,又可以产生一定数量可作单细胞蛋白的酵母 .对于含糖 0.3%左右的洗糟废水可获得约 500 mg/L(干重 )的酵母 ,并可使废水 COD降解约 80% .     

纳米级方解石结构参数的表征

从晶体化学、晶体结构的角度．根据方解石的晶胞参数、晶体内原子排列的特点等,提出了方解石最小颗粒的假设。通过对纳米级方解石颗粒晶胞数、原子数、表面晶胞数和表面原子数的计算,讨论了它们与纳米级方解石颗粒尺寸大小的相关规律．并结合纳米微粒的特性对其进行了简要分析。     

微生物燃料电池构造研究进展

微生物燃料电池(Microbial fuel cell,MFC)的研究在近几年获得了快速发展.产电微生物在厌氧条件下氧化底物释放电子和质子,电子通过导线传递给阴极,从而在外电路中形成电流,而质子通过质子交换膜进入阴极与电子和氧气结合生成水.微生物燃料电池的研究与应用开发涉及到从微生物、电化学到材料学和环境工程等科学领域的交叉,特别是废水处理能与微生物产电相结合的研究成果,使污水、污泥、垃圾等环境污染物的治理有可能成为生物质能源的生产过程,展示了微生物燃料电池的广泛应用前景.本文着重综述微生物燃料电池在构造上的进展,并介绍了其在水处理中的应用前景.图8参56     

Comparison of Ground Water Bacterial Cell Sizes from the Agricultural, Domestic and Industrial Areas of Mysore District, Karnataka State, India

A two-year study on temporal variations in the ground water heterotrophic bacterial cell sizes of free living bacteria(FLB)and particle bound bacteria(PBB)from the agricultural,domestic and industrial areas was carried out from Februar y2005 to January 2007.The overall mean cell length of FLB and PBB was similar in all the ground water studied.However,the season wise grouped data revealed significant seasonal changes in cell length of FLB and PBB,as smaller bacteria were noticed during rainy season in the ground water in agricultural area in both the years,and only in the second year of study in domestic and industrial areas.Generally,it was noticed that there were summer maximum and rainy minimum values of the cell length of PBB in the ground water in agricultural,domestic and industrial areas in the second year of study.The Pearson's correlations showed the presence of 8(in agricultural area),5(in domestic)and 3(in industrial) significant correlations with environmental(Physico-chemical)parameters,respectively.The regression analysis revealed that as much as 12%of variation in the mean length of FL Bwas due to NO3( )in agricultural area and 9%due to total solids( )indomestic area.However,the 8% variation in bacterial cell size of FLB was due to Mg( )in industrial area.Whereas,13%variation in mean length of PBB was due to S04( )in agncultural area and 10%due to total anions of strong acid(TASA)( )in domestic area.Furthermore,10% of variation Was due to PO4( )in industrial area.Thus,the statistical analysis revealed that several environmental variables were potentially responsible for some of the temporal variations in aquatic heterotrophic bacterial cell size,suggesting probably the stressed environment in these ecosystems.