菌株Dysgonomonas mossii的分离及产电特性

为了获得一株产电菌株,并研究其产电性能。采用厌氧分离法从微生物燃料电池中分离出一株新的产电菌株LY-2,通过菌株形态、生理生化特性及16S rDNA系统发育分析做分类学鉴定,采用循环伏安扫描及菌种在微生物燃料电池中产电情况做产电特性验证。结果表明,该菌与Dysgonomonas mossii最相近,命名为Dysgonomonas mossii LY-2。循环伏安扫描显示,该菌具有电化学活性,接种到微生物燃料电池中,以牛肉膏为燃料产生的最大电压为0.61V,最大功率密度为104.3 mW/m2,具有在微生物燃电池中产电研究和应用的前景。     

玉米幼苗对芘污染土壤微生物活性及多样性的影响

通过盆栽土培试验研究了玉米幼苗生长期间对芘污染土壤微生物活性及多样性的影响。结果表明,玉米加快了土壤中芘的降解,提高了芘在土壤中的降解速率。试验期间,根际土中可提取态芘含量显著低于非根际土,根际土微生物生物量碳、微生物熵、多酚氧化酶和脱氢酶活性均高于非根际土,代谢熵低于非根际土。脂肪酸（FAME）分析结果表明,与非根际土相比,芘污染玉米根际土微生物群落结构发生了显著的变化,主要表现在真菌特征脂肪酸以及真菌/细菌的比值显著升高,细菌和GN^-细菌特征脂肪酸显著降低,且这种效应随着培养时间的推移在P〈0.01水平显著。根际土和非根际土中丛枝菌根真菌、GN^＋细菌和放线菌特征脂肪酸差异随着培养时间的延长逐渐加大,45 d时其差异均在P〈0.05水平显著。     

小型化土壤微生物燃料电池电信号放大电路的设计与运行

为了提高对小型化的土壤微生物燃料电池(microbial fuel cells,MFCs)产电信号的检测能力,构建了采用加Cu~(2+)处理土壤进行产电的小型化单室MFCs,并设计和制作了基于集成运算的信号放大器,设计放大倍数100倍。将信号放大器与MFCs连接后,采用数据采集卡连续记录土壤产电的原始电压以及放大后的电压。结果显示,土壤产电电压在4 mV附近波动,而放大后的电压升至400 mV左右。统计显示原始电压与放大后的电压相关性达到极显著水平(P0.001)。同时还发现,并非每个电压数值都严格放大100倍,而是倍率存在5%的误差,原因主要在于集成运算放大芯片存在失调误差和温度漂移误差。本研究为实现小型化MFCs产电信号的检测提供了依据。     

微生物燃料电池去除废水中抗生素类污染物的研究进展

抗生素被广泛用于医疗、畜牧以及水产养殖等领域,大量抗生素未经代谢就进入环境,由此引起的细菌耐药性问题严重威胁着生态环境和人体健康。因而,如何有效控制废水中的抗生素和抗性基因污染成为近年来的研究重点。微生物燃料电池(Microbial fuel cells,MFCs)利用微生物催化降解有机物,在产电的同时实现废水处理和污染控制,是近些年研究较多的一种处理技术。本文综述了MFCs对废水中抗生素、抗性基因等污染物的去除效果、降解机理以及降解过程中微生物群落的变化规律,分析了MFCs与其它技术耦合的效果和机制,概述了应用MFCs构建传感器在线监测抗生素等方面的研究进展。结果表明:MFCs对多种抗生素都具有良好的去除效果,随着反应器构型、抗生素种类以及浓度和运行时间等参数的不同,抗生素、抗性基因的去除效果以及阳极微生物群落有较大差异;MFCs与人工湿地等技术的耦合,有利于增强抗生素的去除效果,为MFCs的实际应用提供了新方向;利用MFCs作为生物传感器可实现废水中抗生素含量的在线监测,但目前尚处于起步阶段。基于上述结论,MFCs可以有效地去除废水中的抗生素,但对抗生素耐药基因的控制效果还亟待研究;如何实现MFCs的长期稳定运行并实际应用是后续研究的重点方向。     

土壤中细菌产氨代谢对农田生态系统的意义

土壤细菌利用尿素产氨不仅可以直接影响土壤中氮源的循环利用和土壤氮素肥力,并且有助于酸化土质的改良。该文就土壤中细菌利用尿素产氨的生物学特征及分子调控机制,影响土壤尿素酶活性的土壤化学特性、环境因素、尿素来源以及微生物间相互作用进行等研究进展进行了综述分析。指出土壤中尿素酶活性是检测土壤质量和土壤肥力的重要指标之一,它与固氮作用、土壤改良和土壤中其他产氨代谢有密切关系,土壤中尿素酶的活性指标对土壤氮素肥力评价和农作物生产具有重要意义。     

不同磷肥水平下丛枝菌根菌对玉米修复芘污染土壤的影响

盆栽试验研究了不同磷肥水平下接种丛枝菌根菌（Arbuscular mycorrizal fungi,AMF）对玉米修复芘污染土壤的影响。结果表明,在施磷水平为20和80 mg/kg条件下,50 mg/kg芘处理土壤中丛枝菌根菌能够正常侵染玉米根系,侵染率没有显著变化;土壤芘污染对玉米的生长有抑制作用,缺磷土壤中施磷能够缓解土壤芘对玉米生长的抑制作用。培养60 d后,高磷（80 mg/kg）和低磷（20 mg/kg）条件下,玉米接种AMF处理土壤芘残留浓度分别比相应的不接种处理降低了38%和35%,比相应无玉米的对照处理降低了53%和58%。表明玉米接种混合AMF能够显著降低土壤芘残留浓度,促进土壤芘的去除。与P 20 mg/kg处理相比,P 80 mg/kg处理玉米接种及不接种AMF的土壤芘残留浓度分别降低了16%和19%,表明缺磷土壤中施磷对玉米及菌根玉米去除土壤芘均有一定促进作用。土壤微生物碳量与土壤芘的去除率显著正相关,接种AMF和P 80 mg/kg处理均能够显著增加土壤微生物碳量,因此土壤微生物数量的增加可能是其促进土壤芘的去除的重要原因。     

镉胁迫对洞庭湖湿地土壤微生物数量与活性的影响

为探讨Cd污染胁迫与洞庭湖湿地土壤微生物学特性之间的内在关系,通过野外土样采集和室内模拟胁迫相结合的方法,研究Cd污染胁迫对洞庭湖湿地土壤微生物数量和微生物活性的影响。结果表明,当Cd胁迫浓度为3 mg kg~(-1)时对洞庭湖湿地土壤细菌、微生物总数及土壤微生物生物量碳(SMBC)刺激作用显著,当Cd胁迫浓度为6 mg kg~(-1)时对真菌有显著的刺激作用,而对细菌、放线菌、微生物总数及微生物生物量氮(SMBN)均表现出抑制作用,且随Cd胁迫浓度的进一步增加对细菌、真菌、放线菌、微生物总数及SMBC、SMBN的抑制作用增强;土壤脲酶、蔗糖酶、过氧化氢酶、磷酸酶和脱氢酶活性随Cd胁迫浓度的增加而降低;土壤基础呼吸(SBR)与代谢墒(qCO_2)随Cd胁迫浓度的增加呈上升趋势。放线菌、SMBC、SMBN、土壤脲酶活性、蔗糖酶活性、过氧化氢酶活性、磷酸酶活性、脱氢酶活性、SBR及qCO_2与Cd胁迫浓度相关显著或极显著;Cd胁迫条件下脱氢酶活性的变异系数最大为50.0%,表明脱氢酶活性的变化对Cd胁迫反映最为敏感,可作为洞庭湖湿地Cd污染土壤质量评价的灵敏指标。     

不同污染方式下铅对茶园土壤氮素转化及其相关微生物和酶活性的影响

为探讨不同污染方式的Pb对茶园土壤氮素转化的影响，采用盆栽试验对累积和一次性添加不同浓度Pb条件下茶园土壤中氮素含量、相关微生物和酶活性进行了研究。结果表明：累积污染处理的土壤中Pb全量和有效态含量高于一次污染处理。Pb污染对土壤、茶苗植株的氮含量影响表现为：增加土壤中全氮和¹⁵N含量，减少茶苗地上部全氮和¹⁵N含量。添加Pb浓度为900 mg/kg时，累积污染处理促进根系全氮和¹⁵N含量，一次污染则显著抑制；累积污染处理的茶苗根和地上部中的氮含量显著高于一次污染(P<0.05)。Pb污染对氮循环相关微生物的影响表现为：氨化细菌、自生固氮菌、亚硝酸细菌和硝酸细菌的数量减少，反硝化细菌的数量增加。Pb的不同污染方式对茶园土壤与氮循环相关微生物数量的影响不显著(P>0.05)。Pb污染抑制脲酶、亚硝化还原酶和硝酸还原酶活性，对蛋白酶活性存在“低促高抑”现象；高浓度Pb(900 mg/kg)污染时，累积处理显著增加土壤羟胺还原酶活性，一次处理则显著抑制。两种污染方式对土壤脲酶、硝酸还原酶和羟胺还原酶活性的影响因Pb...     

重金属污染土壤的微生物学评价

随着研究方法 改进，采用微生物学指标评价土壤重金属污染越来越受人们关注。比较敏感的指标有：对重金属敏感细菌与耐性细菌之比，脱氢酶活性与土壤有机碳之比，代谢商，微生物生物量碳与土壤有机碳之比，异养因氮菌的固氮作用。但微生物的生物是及其活性在受重属金影响的同时也受土壤性质及自然条件的影响，应当把微生物学性质的变化与重金属的形态、植物吸收联系起来评介污染土壤。     

四环素对芘污染农田土壤微生物修复的影响及响应过程

针对城郊农田土壤中多环芳烃和抗生素复合污染的新特征,通过室内模拟土培实验,研究四环素(Tetracycline,TC)胁迫下,降解菌Sphingobium sp.PHE3对长三角典型农田土壤中芘的降解效果和影响机制。研究表明,接种降解菌处理(B)能明显促进土壤中芘的降解,TC的引入可显著抑制土壤中芘的深度降解过程(P0.05)。经过90天培养后,B处理与接菌+添加TC处理(BTC)的降解率分别为40.1%、25.7%,较对照分别提高了23.0倍、14.1倍。通过土壤微生物群落结构多样性分析发现,降解菌数量在经历90天的土壤环境适应期后逐渐快速增加,其数量变化与污染物芘在土壤中含量消减趋势呈负相关;引入芘和四环素对土壤细菌群落结构多样性和功能稳定性具有显著影响(P0.05),然而对土壤真菌群落影响不显著(P0.05)。此外,B和BTC处理条件下,土壤过氧化氢酶活性、荧光素二乙酸酯酶活性和土壤微生物生物量碳氮值显著高于单独添加芘处理(P)和单独添加TC处理(TC),但P处理与TC处理之间无显著差异(P0.05),说明外源污染物(芘或四环素)对于土壤酶活性和微生物生物量碳氮具有显著抑制作用(P0.05),致使降解菌功能作用受到抑制。综上研究结果表明TC可明显抑制土壤中典型四环多环芳烃的微生物降解过程,针对多环芳烃与抗生素复合有机污染农田土壤的微生物强化修复技术有待深入研究。     

微生物燃料电池阳极生物膜微生物群落的PCR-DGGE分析

以养殖废水沼气池沼泥为接种物,构建了乙二胺、三氯化铁改性阳极的无介体单室微生物燃料电池（MFC）体系,均成功实现了连续产电,同时对废水中的污染物也具有很好的去除效果。为了更好地研究微生物燃料电池阳极生物膜的微生物多样性,分别采集了两种MFC阳极生物膜样品,采用PCR-DGGE法研究了一个完整产电周期的启动期（S）、葡萄糖产电稳定期（RG）和养殖废水原水稳定期（RS）的MFC阳极生物膜的微生物群落变化。结果表明,不同时期MFC阳极生物膜的微生物多样性存在明显差异,S-RG、S-RS、RG-RS的微生物群落相似性分别为70.1%、42.0%和50.6%。两种不同阳极富集的生物膜微生物群落相似性仅为48%,这表明不同改性方法所得的阳极对微生物具有选择性作用。对DGGE条带测序和比对发现,不同时期阳极生物膜上优势微生物包括Trichococcus sp.、Thauera sp.、Azoarcus sp.、Azospirillum sp.、Zobellella sp.、Pseudomonas sp.、Aeromonas sp.、Thiobacillus sp.、Desulfovibrio sp.、Thiomonas sp.,其中Pseudomonas sp.、Aeromonas sp.和Desulfovibrio sp.与已报道的相关产电微生物具有较高的序列相似度,这些菌种可能是本MFC体系中的主要产电菌。     

单室结构土壤微生物燃料电池发电性能的影响因子研究

There is limited information about the factors that affect the power generation of single-chamber microbial fuel cells （MFCs） using soil organic matter as a fuel source. We examined the effect of soil and water depths, and temperature on the performance of soil MFCs with anode being embedded in the flooded soil and cathode in the overlaying water. Results showed that the MFC with 5 cm deep soil and 3 cm overlaying water exhibited the highest open circuit voltage of 562 mV and a power density of 0.72 mW m-2. The ohmic resistance increased with more soil and water. The polarization resistance of cathode increased with more soil while that of anode increased with more water. During the 30 d operation, the cell voltage positively correlated with temperature and reached a maximum of 162 mV with a 500 ft external load. After the operation, the bacterial 16S rRNA gene from the soil and anode was sequenced. The bacteria in the soil were more diverse than those adhere to the anode where the bacteria were mainly affiliated to Eseherichia coli and Deltaproteobacteria. In summary, the two bacterial groups may generate electricity and the electrical properties were affected by temperature and the depth of soil and water.     

Indication of Soil Microbial Activity by Electrical Signals of Microbial Fuel Cells with Re-Vegetated Red Soils

Electrical signals generated by microbial fuel cells (MFCs) may potentially indicate overall soil microbial activity. This study aimed to validate whether a significant correlation existed between soil microbial activity and electrical signals in different soils. Re-vegetated red soils with four vegetation types and unplanted eroded red soil were collected and packed into MFCs. The voltage of the MFCs was recorded during operation. Electrical signals including start-up time (ST), peak voltage, and coulomb quantity were extracted from the voltage curves. Soil dehydrogenase activity (DHA) was determined as a reference method to verify the reliability of the electrical signals. After MFC operation, the anodic bacterial community was analyzed by Illumina sequencing based on the 16S rRNA gene. The results indicated that ST was significantly correlated with DHA, along with soil organic carbon content. The linear regression model described the optimal relationships for ST and DHA. Clostridium and Acinetobacter constituted the dominant genera on the anode of the MFCs. The results demonstrated that ST may indicate soil microbial activity in re-vegetated red soils.     

Using electrical signals of microbial fuel cells to detect copper stress on soil microorganisms

A method based on microbial fuel cells (MFCs) was used to evaluate the effects of copper (Cu²⁺) on soil microorganisms. Soil spiked with 50–400 mg kg^?1 of Cu²⁺ as CuCl₂ was incubated for 24 hours before being packed into the MFC anode chambers and assayed for dehydrogenase activity (DHA), substrate‐induced respiration (SIR) and microbial biomass carbon (C_mic). Soil was amended with 5% (w/w) glucose to accelerate ‘start‐up’ and improve power generation, followed by 150 hours of operation. Anode biofilm and soil was extracted to recover total nucleic acids and the 16S rRNA gene was subjected to PCR‐DGGE, sequencing and phylogenetic analysis. Results showed that increases in soil Cu²⁺ concentrations reduced voltage and postponed start‐up. The quantity of generated electrons within 48 hours was 32.5 coulomb (C) in the without‐Cu control and decreased with increasing Cu²⁺ concentrations (11.7, 7.7, 2.0 and 1.3 C under 50, 100, 200 and 400 mg kg^?1 Cu²⁺, respectively). Cyclic voltammetry identified decreased soil electrochemical activity with increasing Cu²⁺ concentrations. The results indicate that Cu²⁺ reduced electrical signals by inhibiting the electrochemical activity, metabolic activity and biomass of microorganisms. The 16S sequences of recovered anodic bacteria were assigned to Firmicutes, including Bacillaceae, Acetobacteraceae, Clostridium, Bacillus and Sporolactobacillus. In general, the DGGE band intensity of anodic bacteria decreased with increasing Cu²⁺ concentrations, except for bands assigned to Firmicutes and Bacillus, which increased with increasing Cu²⁺ concentrations. We suggest that the short‐term electrical signals generated from MFCs with contaminated soil can be used to assess the toxic effect of heavy metal pollutants on soil microorganisms.     

Arsenic modulates the composition of anode-respiring bacterial community during dry-wet cycles in paddy soils

Purpose

Bacteria able to extracelluar respiration, which could be enriched in the anode of microbial fuel cells (MFCs), play important roles in dissimilatory iron reduction and arsenic (As) desorption in paddy soils. However, the response of the bacteria to As pollution is unknown.

Materials and methods

Using soil MFCs to investigate the effects of As on anode respiring bacteria (ARB) communities in paddy soils exposed to As stress. The soil MFC performances were evaluated by electrochemical methods. The bacterial community compositions on anodes were studied using Illumina sequencing.

Results and discussion

In wet 1 phase, polarization curves of MFCs showed cathode potentials were enhanced at low As exposure but inhibited at high As exposure. In the meantime, anode potentials increased with As levels. The dry-wet alternation reduced As levels in porewater and their impacts on electrodes microorganisms. Arsenic addition significantly influenced the anode microbial communities. After dry-wet cycles, Deltaproteobacteria dominated in the anode with high As.

Conclusions

The dynamic changes of the communities on cathodes and anodes of soil MFCs in paddy soils with different As addition might be explained by their different mechanisms for As detoxification. These results provide new insights into the microbial evolution in As-contaminated paddy soils.

     

混合菌群强化去除泥浆体系中菲、芘的效果及影响因素

通过室内泥浆体系模拟试验,研究了混合微生物菌群(嗜热菌和多环芳烃特异性降解菌),在40℃条件下(两类微生物均能较快生长繁殖),对泥浆体系中代表性多环芳烃菲、芘的去除效果及其影响因素(水土比,葡萄糖、淀粉、水杨酸及其浓度)。结果表明:泥浆体系中混合微生物菌群对多环芳烃的去除效果显著(P0.01),单日菲去除率最大可达20.0%,芘达15.3%。随着反应进程的进行,菲和芘的去除率提高,去除速率则逐步降低,菲的半衰期1.8天小于芘4.9天,因此菲的去除较芘更快。试验得到该泥浆体系中混合微生物菌群去除多环芳烃最合适的水土比为2︰1,碳源为葡萄糖,浓度TOC_(葡萄糖):TOC_(PAHs)为2︰1。该研究结果可为泥浆体系中混合微生物菌群强化修复多环芳烃污染土壤的技术研发提供理论基础和技术支撑。     

Enhanced Degradation of Atrazine by Soil Microbial Fuel Cells and Analysis of Bacterial Community Structure

Atrazine degradation in soil microbial fuel cells (MFCs) under different anode depths and initial concentrations is investigated for different redox soil conditions, and the microbial communities in the anode and different layers are evaluated. Atrazine degradation is fastest in the upper layer (aerobiotic), followed by the lower layer (anaerobic). A removal efficiency and a half-life of 91.69% and 40 days, respectively, are reported for an anode depth of 4 cm. The degradation rate is found to be dependent on current generation in the soil MFCs rather than on electrode spacing. Furthermore, the degradation rate is inhibited when the initial atrazine concentration is increased from 100 to 750 mg/kg. Meanwhile, the exoelectrogenic bacteria, Deltaproteobacteria and Geobacter, are enriched on the anode and the lower layer in the soil MFCs, while atrazine-degrading Pseudomonas is only observed in very low proportions. In particular, the relative abundances of Deltaproteobacteria and Geobacter are higher for lower initial atrazine concentrations. These results demonstrate that the mechanism of atrazine degradation in soil MFCs is dependent on bioelectrochemistry rather than on microbial degradation.     

Analysis of bacterial communities on alkaline phosphatase genes in soil supplied with organic matter

Abstract

We studied the effects of the application of organic matter (OM) and chemical fertilizer (CF) on soil alkaline phosphatase (ALP) activity and ALP-harboring bacterial communities in the rhizosphere and bulk soil in an experimental lettuce field in Hokkaido, Japan. The ALP activity was higher in soils with OM than in soils with CF, and activity was higher in the rhizosphere for OM than in the bulk soil. Biomass P and available P in the soil were positively related to the ALP activity of the soil. As a result, the P concentration of lettuce was higher in OM soil than in CF soil. We analyzed the ALP-harboring bacterial communities using polymerase chain reaction based denaturing gradient gel electrophoresis (DGGE) on the ALP genes. Numerous ALP genes were detected in the DGGE profile, regardless of sampling time, fertilizer treatment or sampled soil area, which indicated a large diversity in ALP-harboring bacteria in the soil. Several ALP gene fragments were closely related to the ALP genes of Mesorhizobium loti and Pseudomonas fluorescens. The community structures of the ALP-harboring bacteria were assessed using principal component analysis of the DGGE profiles. Fertilizer treatment and sampled soil area significantly affected the community structures of ALP-harboring bacteria. As the DGGE bands contributing to the principal component were different from sampling time, it is suggested that the major bacteria harboring the ALP gene shifted. Furthermore, there was, in part, a significant correlation between ALP activity and the community structure of the ALP-harboring bacteria. These results raise the possibility that different ALP-harboring bacteria release different amounts and/or activity of ALP, and that the structure of ALP-harboring bacterial communities may play a major role in determining overall soil ALP activity.     

Long-term electricity production from soil electrogenic bacteria and high-content screening of biofilm formation on the electrodes

Purpose

This study was conducted to determine the existence of soil bacteria in soil by soil microbial fuel cell (SMFC). The main objectives were (1) to differentiate the type of soil which will influence the electricity production, (2) to demonstrate the impact of different volume of soil in the MFC and feeding MFC for long-term electricity production, and (3) to conclude that electricity production is directly proportional to the biofilm formation on the anode surface.

Materials and methods

MudWatt kits were purchased from Keego Technologies USA, and 22 identical SMFCs were designed to study the electricity production from agricultural soil (S1) and vermicompost soil (S2). Ten milliliters of bioslurry is fed in SMFC to study the stability of electricity production at different stages. Microbes were isolated and characterized from the surface of the electrode. Biofilm analyses were done by high-content screening (HCS) system using 10 μl of acridine orange (100 μg/ml) at different stages of biofilm, and scanning electron microscopy is applied to confirm the matured biofilm on the surface of the anode.

Results and discussion

Application of bioslurry at different stages of electricity production conquers the normal energy recovery of the SMFCs and S2 soil with bioslurry sample produced the highest open circuit voltage (OCV) of 2.8 V (460 days) and S1 soil sample with bioslurry produced 1.7 V (364 days). The difference between SMFCs and MudWatt kits significantly confirms that increasing the volume of soil in the anode part increases the electricity production. The maximum OCV of S1 and S2 in MudWatt kits were 1.5 V (90 days) and 1.8 V (190 days), respectively. Increased volume of soil in our SMFCs produce maximum OCV of 1.8 V (S1 for 173 days) and 2.2 V (S2 for 240 days), and HCS analysis of biofilm at different stages reveals that electricity production is directly proportional to the biofilm formation.

Conclusions

Thus, it was concluded that the nature of soil and soil bacterium is important for the electricity production, and S2 soil sample produces maximum electricity than the S1 soil sample. Feeding of SMFCs with bioslurry aids the long-term and stabilized electricity production in both the soil samples.