生物阳极及其反转为生物阴极降解氯霉素

为了探讨生物阳极能否降解氯霉素以及生物阳极反转为生物阴极后能否替代生物阴极,通过驯化生物阳极降解氯霉素和生物阳极反转为生物阴极的实验,表明生物阳极经过长期氯霉素浓度梯度增加(5~80 mg·L-1)的驯化,具有较好产电能力的同时,对氯霉素也具有一定的降解能力(k=0.098 5).生物阳极反转为生物阴极后并将电位恒定在-0.40 V vs.SHE时,该生物阴极相对于反转前生物阳极的电位(-0.20 V vs.SHE)有了明显的降低,导致微生物活性受到一定的影响,但阴极生物膜仍具有较强的催化降解氯霉素的能力,其还原降解速率常数k为0.264 3,明显高于非生物阴极对照(k=0.160 9).生物阳极反转生物阴极的模式不仅实现了氯霉素的硝基还原,而且发生了芳香胺产物侧链的完全脱氯和羰基还原反应.     

微生物光电化学池去除硝酸盐氮:以PANI/TiO2-NTs为光阳极

利用微生物光电化学池(MPEC)去除污染物是一种经济高效环保的方法.本实验在制备获得聚苯胺/二氧化钛纳米管阵列(PANI/TiO_2-NTs)复合光电极的基础上,构建了由PANI/TiO_2-NTs光阳极和生物阴极组成的MPEC系统,并对其去除硝酸盐氮(NO~-_3-N)的性能进行研究.结果表明,PANI负载时间为80 s时,PANI/TiO_2-NTs电极光电性能最佳,相比于TiO_2-NTs电极光电流密度增大约一倍,PANI的修饰有效提高了光能利用率.构建的MPEC系统能在无外加电压的条件下利用光能驱动实现自养反硝化脱氮,NO~-_3-N的生物降解符合准一级反应动力学方程.光响应电流密度越大,系统反硝化脱氮性能越好,NO~-_3-N初始浓度为25 mg·L~(-1)时,当光响应电流密度从0.17 mA·cm~(-2)增加至0.67 mA·cm~(-2),平均反硝化速率从0.83 mg·(L·h)~(-1)增大到2.83 mg·(L·h)~(-1).对生物阴极微生物膜进行了高通量测序,发现Pseudomonas所占比例最大(27.37%)为优势菌属.分析认为PANI/TiO_2-NTs光阳极产生的光生电子通过外电路传递到阴极,Pseudomonas、Alishewanella和Flavobacterium等具有自养反硝化能力和电化学活性的微生物可直接利用电极上的电子作为唯一的电子供体进行自养反硝化脱氮.     

Response of anaerobes to methyl fluoride, 2-bromoethanesulfonate and hydrogen during acetate degradation

To use the selective inhibition method for quantitative analysis of acetate metabolism in methanogenic systems,the responses of microbial communities and metabolic activities,which were involved in anaerobic degradation of acetate,to the addition of methyl fluoride(CH3F),2-bromoethanesulfonate(BES)and hydrogen were investigated in a thermophilic batch experiment.Both the methanogenic inhibitors,i.e.,CH3F and BES,showed their effectiveness on inhibiting CH4 production,whereas acetate metabolism other than acetoclastic methanogenesis was stimulated by BES,as reflected by the fluctuated acetate concentration.Syntrophic acetate oxidation was thermodynamically blocked by hydrogen(H2),while H2-utilizing reactions as hydrogenotrophic methanogenesis and homoacetogenesis were correspondingly promoted.Results of PCR-DGGE fingerprinting showed that,CH3F did not influence the microbial populations significantly.However,the BES and hydrogen notably altered the bacterial community structures and increased the diversity.BES gradually changed the methanogenic community structure by affecting the existence of different populations to different levels,whilst H2 greatly changed the abundance of different methanogenic populations,and induced growth of new species.     

Hydrogen gas production in a microbial electrolysis cell by electrohydrogenesis

Electrohydrogenesis is a bio-electrochemical process where organic material is microbially oxidized to protons and electrons, which in turn are reduced to form hydrogen gas (H₂). The reactor in which these reactions occur is termed a microbial electrolysis cell (MEC). The microorganisms that colonize the anode are known as electricigens and behave as biological catalysts, significantly reducing the energy required to drive this process. Electricigens are capable of complete substrate degradation, leading to very high cathodic H₂ recovery efficiencies from sources previously considered organic waste. In this short review, the origination of the bio-electrochemical system (BES) is introduced, mechanisms for electron transfer between microbe and electrode are discussed, the challenges these electrochemical systems face are presented, and finally an overview of current MEC systems and their respective performance is evaluated. Electrohydrogenesis has established itself as a promising technology for sustainable H₂ production from renewable sources.     

不同温度下的土壤微生物呼吸及其与水溶性有机碳和转化酶的关系

为研究不同温度下的土壤微生物呼吸及其与水溶性有机碳(DOC)和转化酶的关系,设置了室内培养实验.采集南京市周边老山、紫金山、宝华山的土壤,研究不同土壤的微生物呼吸对温度升高的响应规律,并分析土壤DOC含量及转化酶活性.结果表明,不同土壤的累积微生物呼吸与土壤温度之间的关系均可用指数方程描述,其P值均达到极显著水平(P0.001),不同地点土壤的微生物呼吸温度敏感系数(Q10值)在1.762~1.895之间变异.累积土壤微生物呼吸的Q10值随着土壤温度升高表现出降低的趋势.培养后27 d土壤微生物呼吸的Q10值与培养后1 d的Q10值无显著差异(P0.05),这表明难分解有机质的温度敏感性与易分解有机质的温度敏感性一致.对于所有土壤而言,累积土壤微生物呼吸与DOC含量之间存在极显著(P=0.003)的线性回归关系,DOC可以解释累积土壤微生物呼吸31.6%的变异性.无论是单独分析不同土壤还是综合所有土壤的测定结果,累积微生物呼吸与土壤转化酶活性均存在极显著(P0.01)的一元线性回归关系,由此说明转化酶活性是衡量土壤微生物呼吸大小的一个较好的指标.     

微生物光电还原CO2合成乙酸对外电压的响应机制

以TiO₂光阳极结合自养型生物阴极,构建双室微生物光电合成（MPES）系统,以光能作为主要的能量来源,探究MPES还原CO₂合成乙酸的性能及其限制因素.结果表明,光阳极取代纯电化学阳极显著降低了MPES生物阴极对外电压的需求.MPES能持续稳定运行,平均产乙酸速率为（1.18 ±0.11） mmol/（L·d）,法拉第效率为45.75%±3.97%.光阳极驱动阴极产生氢气,推测阴极微生物倾向于利用氢转移的方式来进行电子传递.外加电压通过影响光阳极的给电子能力从而对MPES的性能产生显著的影响,当外电压从0.4V升高至0.6V时,MPES的电流,乙酸产量和法拉第效率都显著提高,系统的性能主要受限于阳极.当外电压高于0.6V,系统电流,乙酸产量的增速减缓,法拉第效率在外加电压0.8V时达到最大值,随后下降,表明生物阴极的得电子能力已经达到饱和,此时MPES的性能主要受限于阴极.作为电子传递中间体,H₂的不完全利用是法拉第效率没有随着外电压的增加进一步提升的原因.     

微生物电解系统生物阴极的硫酸盐还原特性研究

针对传统硫酸盐生物还原方法中供氢体系能耗大和氢气利用率低的特点,构建双极室微生物电解系统(microbial electrolysis system,MES),研究了微生物利用阴极作为电子供体去除废水中硫酸盐及电子利用的特性.外加电压为0.8 V时,MES生物阴极在36 h内SO2-4平均去除量为109.8 mg·L-1,平均还原速率可达73.2 mg·(L·d)-1.运行时MES的最高电流密度为50~60 A·m-3,电子回收率为(43.3±10.7)%,约90%的电子被用于还原SO2-4.微生物利用MES阴极产生的H2作为电子供体还原SO2-4,主要还原产物为溶解态的S2-和气态的H2S,还原过程主要发生在前12 h.对MES施加不同外加电压的实验显示,外加电压为0.8 V时的SO2-4去除率和电荷量都比0.4 V时高;但0.4 V情形下MES的电子回收率可达到70%,且周期结束时阴极H2低于检出限,推测微生物可以直接利用阴极的电子从而提高了能量效率.实验结果最终表明,微生物可利用MES的阴极进行代谢去除废水中的SO2-4,阳极微生物产生电子降低了系统能耗,这为含硫酸盐废水的高效低耗处理提供了新的研究思路.     

Coupled biodegradation of p-nitrophenol and p-aminophenol in bioelectrochemical system: Mechanism and microbial functional diversity

Biodegradation mechanisms and microbial functional diversity during coupled p-nitrophenol (PNP) and p-aminophenol (PAP) degradation were studied in a bioelectrochemical system. PNP in the biocathode and PAP in the bioanode were almost completely removed within 28hr and 68hr respectively. The degradation followed the steps including hydrating hydroxyalkylation, dehydrogenating carbonylation, and hydrolating ring cleavage, etc. Metagemomic analysis based on the KEGG and eggNOG database annotations revealed the microbial composition and functional genes/enzymes related to phenol degradation in the system. The predominant bacteria genera were Lautropia, Pandoraea, Thiobacillus, Ignavibacterium, Truepera and Hyphomicrobium. The recognized biodegradation genes/enzymes related to pollutant degradation were as follows: pmo, hbd, & ppo for phenol degradation, nzba, amie, & badh for aromatic degradation, and CYP & p450 for xenobiotics degradation, etc. The co-occurrence of ARGs (antibiotic resistant genes), such as adeF, MexJ, ErmF, PDC-93 and Escherichia_coli_mdfA, etc., were annotated in CARD database during the biodegradation process. The Proteobacteria & Actinobacteria phylum was the primary host of both the biodegradation genes & ARGs in this system. The microbial functional diversity ensured the effective biodegradation of the phenol pollutants in the bioelectrochemical system.     

冬季低温下MBR与CAS工艺运行及微生物群落特征

研究了在冬季低温条件下,膜生物反应器(MBR)与传统活性污泥法(CAS)工艺运行效果及微生物群落特征的差异,对工艺出水水质和微生物活性进行了分析,并借助454焦磷酸高通量测序法对微生物群落组成和结构进行了解析.结果表明,三套对比工艺(MBR两套:高污泥浓度R1和低污泥浓度R2,CAS工艺R3)的出水总氮平均去除率分别为85.2%、56.1%、58.8%;NH+4-N的平均去除率分别为99.7%、99.7%、59.7%,比硝化速率由大到小依次为R2、R1、R3,比反硝化速率由大到小依次为R3、R1、R2,高浓度MBR污泥具有较好的耐寒特性和氨氮去除效果;从454焦磷酸测序结果看,相似性为97%时,菌群丰富度:R2>R3>R1,多样性:R2>R1>R3;MBR污泥微生物菌群的组成和丰度与CAS系统有较大不同;R1、R2、R3中主要的硝化菌为Nitrospira菌属,总相对度依次为:1.22%、1.64%、0.15%,主要的反硝化菌为Zoogloea菌属、Thauera菌属、Comamonadaceae菌属及Comamonas菌属,总相对丰度依次为:5.8%、4.52%、15.21%;低温环境下,泥龄长、污泥浓度高、TN负荷低的MBR系统有利于硝化、反硝化细菌累积,提升生物脱氮效果.     

石墨烯修饰碳毡电极与微生物相互作用过程中的电化学特征

在希瓦氏菌(Shewanella putrefaciens)呼吸驱动下,成功制备了生源性还原态的氧化石墨烯(r-GO)修饰的碳毡电极,进一步研究了r-GO修饰碳毡电极与微生物相互作用的电化学特征.结果表明:经r-GO修饰的碳毡电极与微生物的相互作用程度得到显著提升,这主要是由于修饰后电极的扩散内阻(R_(dif))得到快速降低的结果.将r-GO修饰后的碳毡电极作为阳极应用于微生物燃料电池(MFC)中,经微生物呼吸驱动下的石墨烯修饰电极,由于R_(dif)降低导致电极的电化学活性增强,使得电极和微生物相互作用程度得到提升,从而缩短了MFC启动时间,提高了MFC的产电能力.研究进一步表明,r-GO对电极的修饰,调控了对电极电化学活性及生源性电子向电极表面的传递过程.     

电子束辐照降解水中氯霉素的研究

本研究对氯霉素(CAP)在不同条件下的电子束辐照降解进行了研究.结果表明,电子束辐照可有效去除水中CAP,低浓度CAP在酸性条件下的辐照降解更为显著,且降解过程符合准一级动力学模型.通过添加不同的自由基清除剂,发现HO·在CAP降解中起关键作用,此外,CAP分子也会吸收辐照而发生分解.水中共存的阴离子和腐殖酸(HA)对CAP辐照降解均有抑制作用,这跟其与HO·的反应速率常数大小有关,并且反应速率越大,其抑制能力越强.CAP在去离子水中的去除率高于其他实际水体,但辐照剂量为4 k Gy时,污水厂污水过滤水和胶体浓缩液中的CAP也可分别去除89.1%和81.7%.利用GC-MS检测到辐照后溶液中有6种中间产物,主要是通过脱水、不对称中心断键和脱酰胺作用形成.此外,IC检测有Cl-、NO-3和NO-2的产生,并且TOC在一定程度上降低,说明部分CAP被矿化.     

Arsenic release from microbial reduction of scorodite in the presence of electron shuttle in flooded soil

Scorodite (FeAsO₄·H₂O) is a common arsenic-bearing (As-bearing) iron mineral in nearsurface environments that could immobilize or store As in a bound state.In flooded soils,microbe induced Fe(Ⅲ) or As(Ⅴ) reduction can increase the mobility and bioavailability of As.Additionally,humic substances can act as electron shuttles to promote this process.The dynamics of As release and diversity of putative As(Ⅴ)-reducing bacteria during scorodite reduction have yet to be investigat...     

模拟氮沉降对太岳山油松林土壤呼吸的影响及其持续效应

以太岳山油松林为研究对象,对林地分别作3种凋落物处理:对照(C)、去凋(B)、去凋+切根(A),并设计了4个氮水平:对照(CK,0 kg·hm-2·a-1,以N计,下同)、低氮(LN,50 kg·hm-2·a-1)、中氮(MN,100 kg·hm-2·a-1)和高氮(HN,150 kg·hm-2·a-1),研究了土壤呼吸速率在施氮后的连续变化,以及与温度、湿度、微生物生物量C、N、土壤酶活性的关系.结果表明:去凋+切根、去凋、对照样方不同施氮水平下土壤呼吸速率基本都在施N后的第1 d处在最高峰,随即下降,切根+去凋、去凋处理样方的土壤呼吸速率在施氮后第3 d趋于稳定,而对照处理样方的土壤呼吸速率一直处于下降状态.施氮在一定程度上抑制了切根+去凋处理的土壤呼吸速率,而促进了去凋处理、对照处理的土壤呼吸速率,并且土壤微生物生物量C、N的变化与土壤呼吸速率变化一致,土壤呼吸速率与土壤酶活性、土壤湿度的拟合关系不显著(p0.05),而与土壤温度的拟合关系显著(p0.05).以土壤温度、土壤湿度构建的复合模型R s=aebTWc预测土壤呼吸的准确性高于单因子模型,施氮降低了每种凋落物处理指数关系模型(R s=aebT)的决定系数R2,并且施氮降低了切根+去凋、去凋处理的温度敏感性指数Q10,而对对照处理的Q10无明显影响.     

内源呼吸过程溶解性代谢产物的光谱特性分析

微生物内源呼吸期对污水处理过程具有重要意义.为了更清晰地了解微生物内源呼吸过程,采用三维荧光光谱、紫外光谱结合呼吸图谱对微生物内源呼吸过程进行解析.结果表明,三维荧光光谱和紫外光谱在内源呼吸各个阶段有明显的不同:1内源呼吸快速下降期(第1 d):腐殖酸峰的激发波长(Ex)和发射波长(Em)分别出现5 nm、6 nm的蓝移,荧光指数f450/500和HIX(humification index)分别减小了9.3%、0.2%,UV253/203和UV254分别增加了37.5%、200%,预示着混合液中可生物降解有机物的存在;2内源呼吸慢速下降期(第2 d):f450/500增加了0.5%,HIX减小0.2%,UV253/203减小了20%,UV254增加了16.7%,预示着细胞可能出现了水解或自溶;3内源呼吸稳定期(第3~5 d):腐殖酸峰基本保持不变预示了微生物适应了饥饿环境.本研究从代谢产物的角度解析了内源呼吸过程,为污水处理过程控制提供了新的思路.     

Soil organic matter and biological soil quality indicators after 21 years of organic and conventional farming

Organic farming systems often comprise crops and livestock, recycle farmyard manure for fertilization, and preventive or biocontrol measures are used for plant protection. We determined indicators for soil quality changes in the DOK long-term comparison trial that was initiated in 1978. This replicated field trial comprises organic and integrated (conventional) farming systems that are typical for Swiss agriculture. Livestock based bio-organic (BIOORG), bio-dynamic (BIODYN) and integrated farming systems (CONFYM) were compared at reduced and normal fertilization intensity (0.7 and 1.4 livestock units, LU) in a 7 year crop rotation. A stockless integrated system is fertilized with mineral fertilizers exclusively (CONMIN) and one control treatment remained unfertilized (NOFERT). The CONFYM system is amended with stacked manure, supplemental mineral fertilizers, as well as chemical pesticides. Manure of the BIOORG system is slightly rotted and in BIODYN it is composted aerobically with some herbal additives. In the third crop rotation period at normal fertiliser intensity soil organic carbon (C_org, w/w) in the plough layer (0–20 cm) of the BIODYN system remained constant and decreased by 7% in CONFYM and 9% in BIOORG as compared to the starting values. With no manure application C_org-loss was severest in NOFERT (22%), followed by CONMIN together with the systems at reduced fertiliser intensity (14–16%). Soil pH tended to increase in the organic systems, whereas the integrated systems had the lowest pH values. At the end of the third crop rotation period in 1998 biological soil quality indicators were determined. Compared to soil microbial biomass in the BIODYN systems the CONFYM soils showed 25% lower values and the systems without manure application were lower by 34%. Relative to the BIODYN soils at the same fertilization intensity dehydrogenase activity was 39–42% lower in CONFYM soils and even 62% lower in soils of CONMIN. Soil basal respiration did not differ between farming systems at the same intensity, but when related to microbial biomass (qCO₂) it was 20% higher in CONFYM soils and 52% higher in CONMIN as compared to BIODYN, suggesting a higher maintenance requirement of microbial biomass in soils of the integrated systems. The manure based farming systems of the DOK trial are likely to favour an active and fertile soil. Both, C_org and biological soil quality indicators were clearly depending on the quantity and quality of the applied manure types, but soil microbial biomass and activities were much more affected than C_org.     

Structural and electrochemical properties of annealed La1-xYxNi3.55Mno.4Alo.3Coo.75 hydrogen storage alloys

The effects of the annealing and partial substitution of Y for La on the structural and electrochemical properties of La_1-xY_xNi_3.55Mn_o.4Al_o.3Cr_o.75 (x = 0, 0.1 and 0.2) alloys were reported in the present work. The single-phased CaCu₅-type structure was retained after La was partially substituted by Y. However, the increase of Y content leads to decrease of the lattice parameters and the unit-cell volume. The annealed La_o.9Y_o.1Ni_3.55Mn_o.4Al_o.3Co_o.75 alloys shows typical isometric microstructure, indicating that the composition segregation is improved by annealing. Y substitution for La in the alloys is effective to improve the electrochemical properties at both room temperature and high temperature. A critical substitution content of Y is found at x = 0.1.     

水环境中化能自养微生物种群及固碳功能研究

化能自养微生物可通过还原性物质的氧化获取化学能以固定无机碳,在缺乏光照的海洋深处、水体沉积物等植物无法生存的环境中固碳,对吸收大气、海洋、湿地中的CO₂具有重要作用。本文基于化能自养微生物的研究现状,概述了其主要固碳途径及参与化能自养固碳的主要微生物类群,着重阐述了化能自养微生物在不同水环境中的固碳功能。同时,本文对水环境中化能自养微生物研究的趋势进行了展望,固碳量的精确计算与化能自养固定的有机碳的存在形式与去向应得到更多研究与探讨,以期增进对碳循环的相关认识。     

Shifts in microbial community structure and diversity in a MBR combined with worm reactors treating synthetic wastewater

The chemical oxygen demand (COD) and NH₃-N removal, membrane fouling, sludge characteristics and microbial community structure in a membrane bioreactor (MBR) coupled with worm reactors (SSBWR) were evaluated for 210 days. The obtained results were compared to those from a conventional MBR (C-MBR) operated in parallel. The results indicated that the combined MBR (S-MBR) achieved higher COD and NH₃-N removal efficiency, slower increase in membrane fouling, better sludge settleability and higher activities of the related enzymes in the activated sludge. Denaturing gradient gel electrophoresis was used to analyze the microbial community structures in the C-MBR and the S-MBR. The microbial community structure in the S-MBR was more diverse than that in the C-MBR. Additionally, the slow-growing microbes such as Saprospiraceae, Actinomyces, Frankia, Clostridium, Comamonas, Pseudomonas, Dechloromonas and Flavobacterium were enriched in the S-MBR, further accounting for the sludge reduction, membrane fouling alleviation and wastewater treatment.     

Structure and function of rhizosphere and non-rhizosphere soil microbial community respond differently to elevated ozone in field-planted wheat

To assess the responses of the soil microbial community to chronic ozone (O₃), wheat seedlings (Triticum aestivum Linn.) were planted in the field and exposed to elevated O₃ (eO₃) concentration. Three treatments were employed: (1) Control treatment (CK), AOT40 = 0; (2) O₃-1, AOT40 = 1.59 ppm•h; (3) O₃-2, AOT40 = 9.17 ppm•h. Soil samples were collected for the assessment of microbial biomass C, community-level physiological profiles (CLPPs), and phospholipid fatty acids (PLFAs). EO₃ concentration significantly reduced soil microbial carbon and changed microbial CLPPs in rhizosphere soil, but not in non-rhizosphere soil. The results of the PLFAs showed that eO₃ concentrations had significant effects on soil community structure in both rhizosphere and non-rhizosphere soils. The relative abundances of fungal and actinomycetous indicator PLFAs decreased in both rhizosphere and non-rhizosphere soils, while those of bacterial PLFAs increased. Thus the results proved that eO₃ concentration significantly changed the soil microbial community function and composition, which would influence the soil nutrient supply and carbon dynamics under O₃ exposure.     

Biodegradation of indole by a newly isolated Cupriavidus sp. SHE

Indole, a typical nitrogen heterocyclic aromatic pollutant, is extensively spread in industrial wastewater. Microbial degradation has been proven to be a feasible approach to remove indole, whereas the microbial resources are fairly limited. A bacterial strain designated as SHE was isolated and found to be an efficient indole degrader. It was identified as Cupriavidus sp. according to 16S rRNA gene analysis. Strain SHE could utilize indole as the sole carbon source and almost completely degrade 100 mg/L of indole within 24 hr. It still harbored relatively high indole degradation capacity within pH 4–9 and temperature 25°C–35°C. Experiments also showed that some heavy metals such as Mn^2 +, Pb^2 + and Co^2 + did not pose severe inhibition on indole degradation. Based on high performance liquid chromatography–mass spectrum analysis, isatin was identified as a minor intermediate during the process of indole biodegradation. A major yellow product with m/z 265.0605 (C₁₅H₈N₂O₃) was generated and accumulated, suggesting a novel indole conversion pathway existed. Genome analysis of strain SHE indicated that there existed a rich set of oxidoreductases, which might be the key reason for the efficient degradation of indole. The robust degradation ability of strain SHE makes it a promising candidate for the treatment of indole containing wastewater.