微生物所协同的天然金红石日光催化作用研究

本文揭示了自然界中可能存在的一种新的矿物和微生物交互作用形式,即微生物通过生物电化学作用参与到半导体 矿物的日光催化作用过程中。模拟日光光源下“产电”微生物与天然半导体矿物金红石交互实验结果显示,金红石的光催 化作用促进了矿物端元的反应速率,提高了电子在微生物和矿物之间的转移效率,使微生物电子传递链末端电子能量得到 提升。二者协同作用可提高微生物或半导体矿物单独作用时对污染物如Cr(Ⅵ)的还原处理效果。该研究为环境污染治理提 供了一种矿物与微生物协同作用新理念。     

天然金红石可见光催化强化微生物还原作用的研究

天然金红石在400～700 nm可见光范围内表现出良好的光吸收特性并具有可见光催化活性。本研究利用双室反应器,将天然金红石可见光催化作用引入微生物原有的电子还原过程。利用电化学分析等手段,对天然金红石可见光催化条件下的还原反应进行研究。金红石光催化条件下,体系整体内阻下降23.5%,功率密度增加57.1%,体系反应效率得到提高;在（0.70±0.01）V（相对于饱和甘汞电极）处发生的微生物还原氧气的反应得以加强;同时反应极化内阻降低93.05%,表明在动力学层面上促进了原有反应的发生。研究证明,可见光下天然金红石的光催化作用强化了微生物对电子受体的还原能力。     

微生物还原铁氧化物矿物的电化学研究

微生物可以还原铁氧化物矿物。本文通过使用电化学方法对铁氧化物矿物在微生物还原作用下的氧化还原特性进行模拟与表征,补充了从新角度对微生物还原铁氧化物矿物的研究。研究结果显示,微生物可直接以铁氧化物矿物作为电子受体将其还原得到二价铁生成物。电化学实验显示,0.2 mA阴极恒电流条件下铁氧化物矿物可以接受电子,同时铁氧化物矿物中的Fe3+在0.89±0.01 V(相对于饱和甘汞电极)时发生还原反应,表明铁氧化物矿物满足被微生物还原的电化学条件。双室微生物-铁氧化物矿物体系研究证实,铁氧化物矿物可以作为阴极接受微生物提供的电子。     

化能自养型微生物利用太阳能途径的实验研究

针对自然界中天然半导体矿物和化能自养微生物之间的能量交换途径进行了详细的实验研究.半导体光电化学实验结果显示,天然半导体矿物在光照情况下产生的光生电子可将Fe3+还原为Fe2+,其中金红石光催化还原Fe3+的效率为12.5%,闪锌矿为7.86%,该过程通过天然半导体矿物的日光催化作用实现了太阳光能→电能→化学能的转化;控制电势的微生物电化学反应实验结果显示,化能自养型微生物A.f.菌的细胞增加量与外界电子传入而生成的Fe2+的量呈线性关系,且有外来电子传入实验组的A.f.生长量是无电子传入组的441%,该过程通过菌的生长代谢作用实现了化学能→生物质能的转化.进一步的光电化学和微生物电化学耦合实验结果证明,在太阳光和天然半导体矿物共同作用下,A.f.菌的对数生长期由无光时的36 h延长到72 h,同时细菌的生长在该能量转化过程中得到了明显促进.在天然闪锌矿催化条件下,有光条件的A.f.菌数量增加到无光条件的1.90倍;而在金红石催化条件下,有光条件的A.f.菌数量增加到无光条件的1.69倍.实验结果说明,在以天然半导体矿物为媒介的情况下,化能自养微生物可间接利用太阳能来获得自身的生长繁殖所需的能量,这一过程也实现了太阳光能→电能→化学能→生物质能的能量转化途径.     

硫化物矿物原电池反应的实验研究进展

自然界中大多数硫化物矿物都有良好的导电性,具有半导体的性质.当具有不同电极电位的矿物在溶液中接触在一起,就会形成原电池发生电化学腐蚀,其中电极电位低的矿物作为原电池的阳极发生氧化反应,其溶解会加剧,而电极电位高的矿物作为原电池的阴极发生还原反应,其溶解会受到抑制.     

红壤中微生物群落对半导体矿物日光催化作用的响应

本研究选取天然红壤作为研究对象,分析其中的含铁半导体矿物光催化作用对本源微生物群落结构的影响。采用聚 合酶链式反应/变性梯度凝胶电泳（PCR-DGGE）,研究了不同原始光照条件的红壤中微生物群落在外源电子作用下群落结 构的改变。DGGE图谱的主成分分析表明,两个不同原始光照环境的土壤样品的微生物群落结构由于原始环境的差异而不同： 原始环境为强光照的样品中微生物群落结构受外源电子影响较小;原始环境为弱光照的样品中微生物群落结构受外源电子 影响较大。这一群落结构改变的差异可能由于原始环境为强光照时半导体矿物光催化作用产生光生电子传递到环境中持续 影响周围的微生物群落,而原始弱光照环境中则缺少光生电子的作用。     

南方红壤微生物群落光电子能量响应特性

地表关键带中时刻发生的物质循环与能量流动过程使其成为地球最活跃的系统之一,其中即包含半导体矿物介导的非光合微生物利用太阳光能量这一微生物-矿物协同作用新途径。特别是富含半导体矿物的天然红壤,为研究关键带中半导体矿物转化太阳能为化学能或者生物质能的微观作用,探索关键带各圈层相互作用提供了新的契机。自海口、长沙两地采集天然红壤样品,经SEM、XRD等分析确定其含有针铁矿、赤铁矿、水钠锰矿等多种铁锰氧化物矿物,紫外可见漫反射吸收谱结果显示此类矿物对可见光具有较好的吸收活性。为考察矿物光电子能量对土壤微生物群落构成的影响,构建双室实验体系利用电化学恒电势技术模拟不同能量光电子,电势模拟矿物光电子能量设置为-0.05 V、-0.25 V(vs.SHE)。实验对比分析了土壤提取液、生理盐水、磷酸盐缓冲液、抗坏血酸溶液(提供有机空穴捕获剂)等不同介质条件下的电化学响应情况,发现0.1 mol/L NaH 2PO4缓冲液条件下体系稳定性最高,电流响应活性期超过30 d,最终体系稳定电流与溶液p H见表1。实验结果显示,阴极施加偏压条件下溶液p H基本稳定,说明水电解反应得以控制并达到动态平衡;恒定偏压下体系电流达到稳定,说明电极与表面微生物间电子转移的电化学过程实现平衡。同时,对比分析红壤样品的电流数据可以发现,海口、长沙两地样品在不同电势下的电流响应情况具有显著差异,预示着不同地区、不同电子能量作用下的微生物群落可能具有不同的响应特性。为进一步明确实验体系中微生物生长代谢状况,使用考马斯亮蓝G250测试总蛋白含量,对比初始阶段发现偏压作用前后蛋白含量基本稳定,表明模拟实验体系中微生物可维持原有代谢水平。本文构建双室电化学实验体系利用恒电势技术模拟不同能量光电子,考察微生物对光电子能量的响应特性。后续结合焦磷酸测序等技术获得群落构成信息,能够进一步揭示光电子能量响应情况下的红壤微生物群落演化特征。     

天然半导体光催化与异养微生物粪产碱杆菌的生长代谢

<正>土壤中广泛存在含铁、锰氧化物等天然半导体矿物(鲁安怀,2003)。经前人研究,天然半导体金红石的光催化作用能有效促进化能自养微生物氧化亚铁硫杆菌(Acidthiobacillus ferrooxi-dans)的生长(吕明等,2008)。对于含有天然半导体矿物和有机质的土壤体系中,以有机质为能     

矿物光电子-微生物体系重金属离子价态调控及其环境效应研究进展

本文综述了典型污染区重金属离子赋存状态与环境风险评价、环境微生物多样性等环境质量因子的关系及其对土壤功能的影响;重点介绍了微生物源电子、半导体矿物光电子对重金属离子的价态调节双向控制;总结了电子穿梭体、空穴捕获剂等小分子有机物对光电子还原重金属离子的影响及机制,以及半导体矿物光电子、重金属价电子协同微生物对重金属离子的还原氧化效率与价态调控;分析了微生物及其表面基团对重金属离子的矿化与转化作用,以及微生物界面固定转化在土壤重金属污染修复中的作用。本综述可为进一步研究微生物和半导体矿物光电子协同作用对重金属离子的定向调节、电子转移途径、晶相转化机制提供指导,对深入探讨光-半导体矿物-重金属离子-微生物多相复杂体系的交互作用具有重要的环境学意义。     

产电生物可渗透活性反应栅法（ePRB）地下水有机污染物修复研究

产电生物可渗透活性反应栅(ePRB)地下水有机污染物修复的技术原理是在地下水流横截面上以可渗透活性反应栅(PRB)的形式设置阳极性生物载体反应单元,其上附着具有生物产电呼吸功能的生物膜,并在接近地表的位置设置阴极氧还原反应单元;阳极上的微生物通过将有机物等污染物质的电子转移至阳极使有机污染物氧化降解,电子再通过外电路传递至阴极并为阴极上发生的氧气还原反应所接受.通过这一过程,可以通过远距离的曝气使被有机物等污染的地下水得到修复.     

Response surface methodology mediated optimization of Remazol Orange decolorization in plain distilled water by Pseudomonas aeruginosa BCH

The bacterium Pseudomonas aeruginosa BCH decolorized and degraded the sulphonated azo dye Remazol Orange in plain distilled water. The effects of different parameters, i.e. pH, temperature and cell mass concentration on the biodegradation of dye in aqueous phase was evaluated using response surface methodology. Optimization was carried out using three-level Box–Behnken design. Predicted values were found to be in good agreement with experimental values (R ² 0.9997 and pred R ² 0.9984), which indicated suitability of the employed model and the success of response surface methodology. Optimum dye decolorization was maximized and the favourable conditions were pH 7.43, temperature 29.39 °C and cell mass concentration 2.88 g l^?1, which resulted in 96.01 % decolorization within 5 h. It was validated from the predicted response (97.37 %). According to the analysis of variance results, the proposed model can be used to navigate the design space. 3D plot analysis disclosed the significant interaction between all three tested factors on decolorization process. The combinations of the three variables predicted during response surface methodology were confirmed through confirmatory experiments. Observations indicated that higher cell mass accelerated the decolorization process. Degradation of the dye was verified through high performance liquid chromatography analysis. Phytotoxicity studies carried out with dye and dye metabolites using Phaseolus mungo, Triticum aestivum and Sorghum vulgare indicated the detoxification of dye.     

Decolorization of Congo red mediated by marine <Emphasis Type="Italic">Alcaligenes</Emphasis> species isolated from Indian West coast sediments

Alcaligenes species capable of degrading highly recalcitrant, carcinogenic, water-soluble dye—Congo red—were isolated from Indian West coastal sediments. Individual strains showed decolorization rates ranging from 76.49 to 98.76% within 24–48 h. Decolorization was most efficient at anoxic conditions catalyzed by intracellular azoreductase enzyme with an activity of 0.032 µmol min^?1 mg^?1 of protein. Degradation was confirmed by HPLC and FTIR analysis. LC/MS analysis of degraded metabolites established the cleavage of the azo bond-producing biphenyl diamine and 1,2′-diaminonapthalene-4-sulfonic acid. These results signify the effectiveness and ease to engineer processes such as feed batch/immobilized cell systems using these strains as biocatalysts to address the problem of global coastal water pollution caused by increased disposal of azo dye-containing industrial effluents.     

Application of a novel definitive screening design to decolorization of an azo dye on boron-doped diamond electrodes

The electrochemical decolorization of the Reactive Violet 5 azo dye on a boron-doped diamond anode was used as a model process to test a novel definitive screening design (DSD). This method allows a dramatic reduction in the number of experiments needed to investigate those systems characterized by a large number of variables. In this study, the effect of nine quantitative parameters was investigated: initial dye concentration (60–120 mg L^?1), current density (100–500 A m^?2), NaCl concentration (5–20 mM), Na₂SO₄ concentration (35–65 mM), pH (3–11), temperature (20–45 °C), inter-electrode distance (0.5–3.5 cm), stirring rate (250–750 rpm) and electrolysis time (2–8 min). Analysis of DSD data showed that four out of the nine factors (initial dye concentration, current density, pH and electrolysis time) were statistically significant. These factors were retained for process characterization using a subsequent central composite design. Overall, the number of experiments was reduced from over 500 to only 41, thus confirming the validity of the proposed approach as a time-saving and efficient method.     

Co-metabolic decolorization of a textile reactive dye by <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis>

In the present study, a widely used reactive dye, Color Index (C.I.) Reactive Blue 268 was utilized for mycoremediation by Aspergillus fumigatus isolated from textile effluent. Complete decolorization of the test dye (0.1 g L^?1) was recorded within 6 days of static incubation at 27 °C in Czapek Dox broth (CDB). However, the isolate was unable to utilize the dye as a sole source of energy in Czapek Dox agar and CDB in absence of sucrose and obligate requirement of a labile carbon source, i.e., sucrose needed for induction of decolorization. Biosorption seems to play the pivotal role in decolorization as evident by coloring of the fungal biomass as that of dye color. The optimal conditions for the highest decolorization were found at 30 °C and pH 6.0 with 6-day-old inoculums supplemented with sucrose (10 g L^?1) and ammonium chloride (2 g L^?1) as a carbon and nitrogen source, respectively. The response of the isolate to increasing dye concentrations was found to be growth inhibitory. Surprisingly, about 65 % of dye decolorization was recorded with heat-inactivated biomass powder within 6 days of static incubation supporting the fact of fungal biosorption. Results of this study have established the candidature of the isolate for biotechnological removal of dyes from disreputable dying effluents.     

海洋铁锰结核对次甲基蓝的氧化性脱色

利用锰氧化物具有高的吸附与氧化还原化学活性的特点,研究了采自东太平洋的铁锰结核对阳离子染料次甲基蓝氧化性脱色特征。结果表明,铁锰结核表面的非均相氧化是次甲基蓝脱色的主要机制。在通常的染料废水浓度范围内,铁锰结核可有效地对次甲基蓝染料废水氧化脱色。随染料浓度降低,铁锰结核投放量增加和粒度减小,次甲基蓝的脱色率明显提高。次甲基蓝的矿化程度(TOC去除率)较高,但仍低于脱色率。pH对次甲基蓝脱色的影响主要体现在对表面配位体形成和对体系还原电位的影响,当pH<4.0时,脱色率随酸度的增加明显提高;当pH在4.0~10.0时,溶液pH值对脱色率影响有限。在铁锰结核连续循环体系中,溶解Mn2 浓度和pH的增加是脱色率不断下降的主要原因。     

Decolourisations and biodegradations of model azo dye solutions using a sequence batch reactor,followed by ultrafiltration

The main objective of this study was to investigate the efficiency of biological treatment of azo dye-containing wastewater with a sequencing batch reactor system, followed by ultrafiltration. The performance of the system was quantified by measuring the chemical oxygen demand and azo dye concentration. The biodegradation was carried out under combined alternating anaerobic and aerobic conditions with Nylosan Yellow E2RL SGR as a model azo dye contaminant. The bioprocess revealed a maximal reduction in chemical oxygen demand and dye removal efficiency of 91 and 85%, respectively. After ultrafiltration of effluent from the biological treatment, the efficiency increased to 94% for chemical oxygen demand and to 97% for the azo dye decolourisation. Samples of activated sludge from the bioprocess were collected for microbial characterisation. Bacteria and fungi were isolated and identified by 16S rRNA gene and ITS1-5.8S rDNA-ITS2 sequence analysis, respectively. Serratia marcescens and Klebsiella oxytoca were the most common bacteria with the highest number present during the aerobic and anaerobic phases of the bioprocess. In addition, a high number of Elizabethkingia miricola, Morganella morganii, Comamonas testosteroni, Trichosporon sp. and Galactomyces sp. were detected. Taken together, our results demonstrated that the sequencing batch reactor system combined with ultrafiltration is an efficient technique for treatment of wastewater containing azo dye. Moreover, the ultrafiltration effectively removes the microbiota from the final effluent resulting in stable product water.     

Microbial decolorization and degradation of crystal violet dye by <Emphasis Type="Italic">Aspergillus niger</Emphasis>

Two fungi were isolated and examined to decolorize crystal violet dye, frequently used as textile dye and in microorganism staining, using basal salt medium under static condition at 30 °C. The more effective fungus gave less dry weight and lower pH indicating that the process was directed toward the decolorization process giving acidic products rather than microbial growth. The effective fungus was identified as Aspergillus niger and was used in the rest of experiments. Increasing the incubation period more than 10 days did not improve the decolorization process, while the best pH was 5.5. The decolorization process was effective (up to 84.6 %) with the examined range of dye concentrations (10–40 ppm). Sucrose content, as a carbon source, more than 1 % did not improve the decolorization process (80.9 %). Using ammonium sulfate as a nitrogen source, instead of sodium nitrate in the original basal medium, lowered the decolorization process, while using corn steep liquor enhanced the biodegradation up to 96.1 %. Although the dye violet color vanishes in acid medium because of decreasing the possibility of extending the benzene chromophore as a result of binding the nitrogen lone pair in the ammonium ion, the UV–Vis spectra and LC–MS–ESI analysis of the bioassay products proved that the decolorization is due to the biodegradation of the dye rather than the resonance factor in acidic medium or biosorption by fungus mycelia.     

双室电化学体系中产电微生物与黄铁矿单晶协同电子转移反应

通过构建产电微生物—黄铁矿双室体系, 应用电化学方法对以黄铁矿单晶电极作为产电微生物电子受体时, 两者间的电子转移过程进行表征和分析.结果显示, 与惰性石墨电极相比, 以黄铁矿单晶作为产电微生物电子受体时, 体系最大功率密度提升132.9%;电化学阻抗谱显示, 黄铁矿单晶电极极化电阻降低98.8%, 表现出优良的电化学反应特性, 表明产电微生物与黄铁矿单晶间具有良好的电子转移活性.籍由产电微生物对底物的氧化作用, 与黄铁矿单晶接受产电微生物电子在0.34 V(相对于饱和甘汞电极)处发生的还原反应, 构成了两者间完整的协同电子转移过程.      

Microbial fuel cell operation using nitrate as terminal electron acceptor for simultaneous organic and nutrient removal

A double-chambered biocathode microbial fuel cell with carbon felt employed as electrodes was developed for wastewater treatment and bioelectricity generation simultaneously. The system was operated in fed-batch mode for over eight batches. The effect of circuit connections on organic and nitrate reduction was investigated. The maximum power density recorded was 21.97 mW/m² at current density of 88.57 mA/m². The Coulombic efficiency and internal resistance of the system were 5% and 100 Ω. Up to 89.9 ± 5.9% of chemical oxygen demand reduction efficiency achieved with an influent of 1123 ± 28 mg/L. There was no significant difference in the chemical oxygen demand reduction when system operated in either open or closed circuit. This study clearly showed that higher nitrate reduction efficiency obtained in closed circuit (74.7 ± 7.0%) due to bio-electrochemical denitrification compared to only 41.7% in the open circuit. The result also successfully demonstrated nitrate as terminal electron acceptor for the cathodic nitrate reduction.