电活性生物膜阳极构建及其对2，4，6-三氯酚同步降解和产电

为实现氯酚（CPs）的高效降解和资源化利用,探究微生物燃料电池（MFC）体系优势功能菌,揭示生物降解路径.接种、驯化长春市南郊污水处理厂的厌氧活性污泥,获得生物膜阳极以构筑MFC-2,4,6-TCP体系,基于扫描电子电镜（SEM）、16S rRNA分析测序方法,考察生物膜阳极微生物的附着情况和优势菌种,基于电化学阻抗（EIS）、循环伏安（CV）和线性扫描伏安（LSV）等电化学分析手段,表征生物阳极的电化学性能和氧化还原能力.结果表明,生物膜阳极微生物种类丰富,其中Geobacter和Acinetobacter分别为MFC-2,4,6-TCP体系产电和降解驯化期的优势功能菌,体系最大输出电压可达0.55 V,最大功率密度为428.65 mW·m-2,对2,4,6-TCP的降解和矿化率可达97.5%和85.4%.随着MFC循环次数的增加,微生物代谢途径多样化,产电菌逐渐演替为协同菌,且优势功能菌对2,4,6-TCP降解的中间产物（环己醇）,其毒性远低于氯酚或苯酚,更利于被微生物利用.该结果可为氯酚废水的实际处理提供新策略和技术参考.     

新型锰氧化菌株Pseudoxanthomonas mexicana S5-3-5X的分离及锰氧化机理研究

锰氧化微生物能催化氧化Mn^II生成锰氧化物（Mn^IV&III）,而生成的锰氧化物可强化水处理体系（如锰砂滤池、湿地）中的微量有机污染物降解及底泥中甲烷的厌氧氧化,因而受到广泛研究.从环境中分离出更多种属和生态位的锰氧化菌是生物强化环境中锰氧化过程的重要基础.依据锰氧化菌株对低浓度营养物的潜在偏好,本研究梯度稀释常用的锰氧化菌培养基（PYG培养基）,配置出5级营养物梯度浓度的培养基.相对于原培养基,从较低浓度的4级培养基中多分离出6个菌属的锰氧化菌株,提高了锰氧化菌株的分离效率.分离出的Pseudoxanthomonas（假黄色单胞菌属）菌属的锰氧化菌株（Pseudoxanthomonas mexicana S5-3_-5X）,属中文文献首次报道.研究发现该菌株能在环境常见条件（pH 6.0~7.8、低营养物浓度（如稀释5~625倍PYG培养基）、50 μmol·L^-1 ~1.6 mmol·L^-1的Mn^II浓度）生长并产生锰氧化活性;可以产生胞外超氧化物和锰氧化蛋白等锰氧化活性物质;基因组具有编码锰氧化模式菌株Pseudomonas putida GB-1的3个Mn^II氧化蛋白的同源基因,并且具有降解一些有机污染物的代谢通路.因此,该菌株具有较好的工程应用潜力.     

Enhanced metronidazole removal by binary-species photoelectrogenic biofilm of microaglae and anoxygenic phototrophic bacteria

High efficient removal of antibiotics during nutriments recovery for biomass production poses a major technical challenge for photosynthetic microbial biofilm-based wastewater treatment since antibiotics are always co-exist with nutriments in wastewater and resist biodegradation due to their strong biotoxicity and recalcitrance. In this study, we make a first attempt to enhance metronidazole (MNZ) removal from wastewater using electrochemistry-activated binary-species photosynthetic biofilm of Rhodopseudomonas Palustris (R. Palustris) and Chlorella vulgaris (C. vulgaris) by cultivating them under different applied potentials. The results showed that application of external potentials of -0.3, 0 and 0.2 V led to 11, 33 and 26-fold acceleration in MNZ removal, respectively, as compared to that of potential free. The extent of enhancement in MNZ removal was positively correlated to the intensities of photosynthetic current produced under different externally applied potentials. The binary-species photoelectrogenic biofilm exhibited 18 and 6-fold higher MNZ removal rate than that of single-species of C. vulgaris and R. Palustris, respectively, due to the enhanced metabolic interaction between them. Application of an external potential of 0V significantly promoted the accumulation of tryptophan and tyrosine-like compounds as well as humic acid in extracellular polymeric substance, whose concentrations were 7.4, 7.1 and 2.0-fold higher than those produced at potential free, contributing to accelerated adsorption and reductive and photosensitive degradation of MNZ.     

土地集约利用程度对华北潮土农田土壤微生物群落丰度和死生物物质积累的影响

土壤微生物决定着土壤生态系统的养分周转状况,其死生物物质在土壤有机碳(SOC)积累中发挥关键作用.然而,目前缺乏对土壤微生物群落丰度及其死生物物质如何响应农业土地集约利用程度调整的了解.为弥补这一知识缺口,基于土地集约化利用程度,设置小麦-玉米周年轮作(CC)、临时草地与小麦种植交替(TG)和多年生草地(PG)这3个处理开展长期定位试验,采用基于数字PCR和微生物标志物氨基糖的检测技术,以探究农业土地集约利用程度调整对土壤细菌和真菌数量,以及细菌、真菌和总微生物死生物物质C积累及其对土壤SOC封存贡献的影响,进一步明确驱动细菌、真菌和总微生物死生物物质C积累的关键因子.结果表明,与土壤细菌群落丰度相比,真菌群落丰度受到农业土地集约利用程度调整的强烈影响,随土地集约利用程度的降低而增加.在3种土地集约利用程度处理下,土壤总微生物死生物物质C均主导SOC积累,对SOC的贡献率分别达到52.78%、 58.36%和68.87%,呈现随土地集约利用程度降低而升高的趋势;真菌死生物物质C占总微生物死生物物质C的比例均大于80%,说明其对总微生物死生物物质C的绝对主导地位,且受土地集约利用程度降低...     

高效石油降解菌修复石油污染土壤与强化机制分析

利用定向驯化高效石油降解菌系对石油污染土壤进行为期120 d原位修复,考察生物强化修复效果、土壤理化性质和酶活性的变化,结合宏基因组测序及生物信息学分析揭示其强化机制.结果表明,与空白对照组(Ctrl)相比,生物修复组(Exp-BT)总石油烃降解率显著提升,增幅达81.23%; 高效石油降解菌生物强化修复期间土壤pH变化稳定,体系氧化能力提高,电导率处于适宜农业活动范围内; 脂肪酶和脱氢酶在修复期间保持较高活性; 另对初始污染土壤样本(B0)、驯化所得高效石油降解菌系样本(GZ)和生物修复后土壤样本(BT)的分析显示,门水平上变形菌门与放线菌门相对丰度增加17.1%,属水平上Nocardioides、Achromobacter、Gordonia和Rhodococcus等丰度明显上升,COG和KEGG物种与功能贡献度分析证明以上菌属对石油烃降解有重要贡献; 修复后土壤中发现高丰度的石油烃相关代谢酶及5个降解基因:alkM、tamA、rubB、ladA 和alkB,分析表明外源石油烃降解菌群的引入增强了微生物相关酶的代谢活性与相应功能基因的表达.     

硫酸盐还原菌对碱性和酸性农田土壤中重金属的钝化效果及其作用机制

通过土壤培养实验考察了硫酸盐还原菌（SRB）包括希瓦氏菌、梭状芽胞杆菌和两者混合菌对碱性和酸性农田土中有效态重金属（Cd、Pb、Cu和Zn）的钝化效果及其作用机制.结果表明,在相同接菌量下,希瓦氏菌处理组对碱性土中有效态重金属的钝化效果优于梭状芽胞杆菌和两者混合菌的处理组;而不同种类的SRB对酸性土中有效态重金属的钝化效果无显著差异.培养第20 d后土壤中有效态重金属的钝化率不再显著变化.SRB处理对碱性土中有效态重金属的钝化率可达80%以上,而对酸性土中有效态重金属的钝化率低于40%.在碱性土中,SRB能够有效还原SO₄^2-,并且提高土壤pH值,使S^2-可与重金属紧密结合,显著提高有效态重金属钝化率.尽管SRB使酸性土壤pH值升高,但土壤仍然呈酸性使SO₄^2-还原受到抑制,不利于有效态重金属的钝化.总体来看,SRB适用于碱性和酸性土壤的重金属污染治理,但与酸性土壤相比,SRB对碱性土壤中有效态重金属的钝化效果更好.     

Bacterial colonization of the phyllosphere of nineteen plant species and antimicrobial activity of their leaf secondary metabolites against leaf associated bacteria

Summary. The scope of this work was to examine whether leaf constitutive secondary metabolites play a role in determining bacterial colonization of the phyllosphere. To this aim, we surveyed nineteen native or cultivated plant species that share a common bacterial pool in a North Mediterranean area, and estimated the size of total and ice nucleation active (INA) bacterial populations on their leaves. Large differences in the colonization of their phyllosphere were found; the population size of epiphytic bacteria ranged from 7.5 × 10² to 1 × 10⁶ CFU/g fresh weight, in eucalypt and celery, respectively. Species native in Mediterranean-type climate areas, particularly those belonging to the group of aromatic plants, are characterized by scarce presence of INA bacteria. The antibacterial activity of essential oils, surface phenolics and leaf tissue extracts was also estimated against the INA strains P. syringae and E. herbicola, isolated from two of these plant species. E. herbicola proved more sensitive than P. syringae. Of the species examined, oregano [Origanum vulgare L. subsp. hirtum (Link.) Ietswaart], an aromatic plant, had the highest antimicrobial activity, whereas six species showed no activity at all. Further experiments were performed with oregano and bean (Phaseolus vulgaris L.) that represent two extremes in their secondary metabolite content. Both plants were inoculated with P. syringae. By the end of incubation, the bacterial population on bean plants was about 100 times higher than that on oregano leaves. Scanning electron micrographs showed that bacterial growth on oregano leaves was confined to sites away from glandular hairs. Results from the bacterial colonization survey together with those from the toxicity tests showed that all species rich in antibacterial secondary metabolites harbored low leaf bacterial populations. These results provide substantial evidence that leaf secondary metabolites function as constitutive defense chemicals against microbial invasions. However, the fact that species with non- or moderately active leaf secondary metabolites are not always highly colonized suggests mediation of other unknown factors, the contribution of which requires further investigation.     

Ammonium-dependent regulation of aerobic methane-consuming bacteria in landfill cover soil by leachate irrigation

The impacts of landfill leachate irrigation on methane oxidation activities and methane-consuming bacteria populations were studied by incubation of landfill cover soils with leachate and (NH₄)₂SO₄ solution at different ammonium concentrations. The community structures and abundances of methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) were examined by PCRDGGE and real-time PCR. Compared with the pure (NH₄)₂SO₄ solution, leachate addition was found to have a positive effect on methane oxidation activity. In terms of the irrigation amount, ammonium in leachate was responsible for the actual inhibition of leachate. The extent of inhibitory effect mainly depended on its ammonium concentration. The suppression of the predominant methaneconsuming bacteria, type I MOB, was responsible for the decreased methane oxidation activity by ammonium inhibition. Methaneconsuming bacteria responded diversely in abundance to ammonium. The abundance of type I MOB decreased by fivefold; type II MOB showed stimulation response of fivefold magnification upon the first addition but lessened to be lower than the original level after the second addition; the amount of AOB was stimulated to increase for 20-30 times gradually. Accumulated nitrate from nitrification strengthened the ammonium inhibition on type I and type II MOB, as a result, repetitive irrigation was unfavorable for methane oxidation.     

共生细菌对盐生小球藻亚砷酸盐代谢的影响

为探讨共生细菌对盐生小球藻（Chlorella salina）亚砷酸盐（As（III））富集和形态转化的影响,从C.salina培养液中分离培养出一株共生细菌,并采用抗生素处理C.salina获得无菌藻,设置0,75,150,300,750 μg/LAs（III）溶液处理带菌和无菌的C.salina,7d后测定C.salina对As（III）的吸收、吸附和富集量,以及培养液和藻细胞内As的形态,计算带菌和无菌C.salina对As（III）的氧化率和去除率;使用不同浓度的As（III）处理共生细菌7d,并以300μg/L的As（III）处理共生细菌不同时间,计算两种情况下共生细菌对培养液中As（III）的氧化率和去除率.结果表明：C.salina的共生细菌为根癌农杆菌（Agrobacterium tumefaciens WB-1）;与无菌C.salina相比,带菌C.salina生长更快、对As（III）的耐性更强.带菌C.salina对As（III）的富集量为103.10~448.12mg/kg、氧化率为78.93%~96.88%、去除率为18.92%~55.21%,显著高于无菌C.salina的富集量（11.68~91.39mg/kg）、氧化率（14.46%~26.39%）和去除率（12.82%~29.15%）,也高于A.tumefaciens WB-1对As（III）的氧化率（4.51%~30.61%）和去除率（1.86%~16.19%）.此外,带菌C.salina胞内还检测到少量的As（III）和甲基砷,而在无菌C.salina胞内没有甲基砷存在.共生细菌促进了盐生小球藻对As（III）的富集和形态转化.     

CO2倍增和施氮对水稻不同生长期土壤反硝化细菌丰度的影响

随着全球气候变化的不断加剧,大气CO₂浓度呈明显增加趋势,这将间接影响土壤-植物-微生物系统的氮循环过程.为研究典型水稻土壤反硝化细菌对CO₂浓度升高的响应规律和机制,借助水稻密闭培养箱,运用实时荧光定量聚合酶链式反应（Real-Time qPCR）分子技术,设置不施氮（0 mg/kg）和常规施氮（100 mg/kg）2个处理,研究CO₂倍增对水稻不同生长期土壤关键反硝化功能细菌（narG、nirK和nirS型）丰度的影响.结果表明:①在2种施氮水平,CO₂倍增显著促进了水稻分蘖期、孕穗期、扬花期和成熟期水稻根系生长（增幅为2.96%~28.4%）、地上部生物量增加（增幅为7.1%~107.3%）以及成熟期籽粒干质量的增加（增幅为19.5%和38.0%）,具有显著的增产效应.②反硝化细菌丰度对CO₂倍增的响应与生育期及施氮水平有关,CO₂倍增在2个施氮水平均抑制分蘖期反硝化细菌的繁殖,显著增加孕穗期反硝化细菌数量;在水稻扬花期,CO₂倍增促进了施氮处理narG和nirS型反硝化细菌数量的增加,在成熟期抑制未施氮处理下narG、nirK和nirS型反硝化细菌的生长.另外,narG、nirK、nirS型反硝化细菌丰度整体表现为narG > nirS > nirK,且随水稻的生长,其在成熟期的丰度均呈降低趋势.nirK和nirS基因同属亚硝酸还原酶,但nirS基因丰度高于nirK,且对CO₂倍增和施氮的响应有所差异.研究显示,CO₂倍增可显著增加水稻生长和产量,不同施氮水平对稻田土壤反硝化细菌丰度的影响存在差异.