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.     

Methanogenic community dynamics in anaerobic co-digestion of fruit and vegetable waste and food waste

A lab-scale continuously-stirred tank reactor (CSTR), used for anaerobic co-digestion of fruit and vegetable waste (FVW) and food waste (FW) at different mixture ratios, was operated for 178 days at the organic loading rate of 3 kg VS (volatile solids)/(m³.day). The dynamics of the Archaeal community and the correlations between environmental variables and methanogenic community structure were analyzed by polymerase chain reactions - denaturing gradient gel electrophoresis (PCR-DGGE) and redundancy analysis (RDA), respectively. PCR-DGGE results demonstrated that the mixture ratio of FVW to FW altered the community composition of Archaea. As the FVW/FW ratio increased, Methanoculleus, Methanosaeta and Methanosarcina became the predominant methanogens in the community. Redundancy analysis results indicated that the shift of the methanogenic community was significantly correlated with the composition of acidogenic products and methane production yield. Different mixture ratios of substrates led to different compositions of intermediate metabolites, which may affect the methanogenic community. These results suggested that the analysis of microbial communities could be used to diagnose anaerobic processes.     

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.     

一种高效的硅胶中氚化水自动化解析技术

文章介绍采用温度自动控制的铸铝加热方式提取硅胶中氚化水的一种高效节能解析技术,并通过实验验证表明,该解析技术对硅胶吸附氚化水样品的最佳解析时间为15 min,此时100 g饱和硅胶样品至少能解析水7～10 mL用于液闪测量,对硅胶中氚化水的平均回收率优于99%,氚记忆效应小于万分之二。该技术与GB12375-90标准提出的氚蒸馏技术相比,具有能同时处理多个样品,可提高硅胶氚吸附样品前处理制样效率、节约能源等特点。     

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。     

A hybrid fuel cell for water purification and simultaneously electricity generation

● A novel hybrid fuel cell (F-HFC) was fabricated. ● Pollutant degradation and synchronous electricity generation occurred in F-HFC. ● BiOCl-NH₄PTA photocatalyst greatly improved electron transfer and charge separation. ● Pollutant could act as substrate directly in ambient conditions without pretreatment. ● The mechanism of the F-HFC was proposed and elucidated. The development of highly efficient energy conversion technologies to extract energy from wastewater is urgently needed, especially in facing of increasing energy and environment burdens. Here, we successfully fabricated a novel hybrid fuel cell with BiOCl-NH₄PTA as photocatalyst. The polyoxometalate (NH₄PTA) act as the acceptor of photoelectrons and could retard the recombination of photogenerated electrons and holes, which lead to superior photocatalytic degradation. By utilizing BiOCl-NH₄PTA as photocatalysts and Pt/C air-cathode, we successfully constructed an electron and mass transfer enhanced photocatalytic hybrid fuel cell with flow-through field (F-HFC). In this novel fuel cell, dyes and biomass could be directly degraded and stable power output could be obtained. About 87 % of dyes could be degraded in 30 min irradiation and nearly 100 % removed within 90 min. The current density could reach up to ~267.1 μA/cm²; with maximum power density (P_max) of ~16.2 μW/cm² with Rhodamine B as organic pollutant in F-HFC. The power densities were 9.0 μW/cm², 12.2 μW/cm², and 13.9 μW/cm² when using methyl orange (MO), glucose and starch as substrates, respectively. This hybrid fuel cell with BiOCl-NH₄PTA composite fulfills the purpose of decontamination of aqueous organic pollutants and synchronous electricity generation. Moreover, the novel design cell with separated photodegradation unit and the electricity generation unit could bring potential practical application in water purification and energy recovery from wastewater.     

污水生物处理系统细菌衰减特征的实验研究

通过衰减速率测定实验和LIVE/DEAD细胞活性染色实验,分析了污水生物处理系统中细菌在好氧环境下的衰减状态.研究发现,细菌的衰减实质上是由生物量减少引起的数量衰减和由细胞活性降低引起的活性衰减两部分构成的.结果表明,硝化系统细菌在衰减过程中由细胞活性降低引起的衰减约占60%,由细胞死亡引起的衰减约占40%;而在异养系统中由活性降低引起的衰减和由细胞死亡引起的衰减分别为80%和20%.     

几种固定化细胞载体的比较

以琼脂、明胶、海藻酸钙、聚乙烯醇和丙烯酰铵凝胶为固定化细胞的包埋固定载体,对其主要包埋条件和性能进行了初步的研究比较。其结果表明,海藻酸钙和聚乙烯醇与琼脂、明胶和丙烯酰胺凝胶相比较,具机械强度较高、传质性能较好,生物毒性较低和固定操作容易等优点,为较好的固定化细胞载体,值得进一步深入研究。