异养硝化-好氧反硝化菌YL的脱氮特性

针对传统自养硝化-厌氧反硝化工艺流程长、脱氮效率低的问题,从驯化成熟且具有高效同步硝化反硝化作用的SBR反应器中筛得1株异养硝化菌YL,经鉴定为铜绿假单胞菌(Pseudomonas aeruginosa),并通过单因子试验和正交试验对其异养硝化和好氧反硝化特性进行了研究.结果表明,菌株YL进行氨氧化作用的最适条件为:碳源为琥珀酸钠、C/N为10、p H为7.0、温度为30℃、转速为160~200 r·min-1,此时氨氧化速率为5.05 mg·(g·h)-1,TOC转化速率为45.95 mg·(g·h)-1,氨氮和TOC去除率分别为100%和90.8%;菌株YL还能够利用亚硝酸盐、硝酸盐和羟胺进行生长代谢,去除率分别为92.7%、93.6%和94.8%;影响菌株YL好氧反硝化性能最主要的因素为C/N,在最优条件(C/N=10,T=30℃,r=200 r·min-1,p H=7)下,硝氮去除率为94.6%,总氮去除率76.3%.表明菌株YL能够独立快速高效地完成异养硝化和好氧反硝化脱氮过程.     

不同构型人工湿地基质中土著菌的耐药性及整合子丰度调查

采用Kirby-Bauer纸片琼脂扩散法分析了夏、冬季节9个不同构型人工湿地中的葡萄球菌(Staphylococcus)、假单胞菌(Pseudomonas)两种土著菌对7种常用抗生素的耐药性,并通过荧光定量PCR检测人工湿地基质中Ⅰ型整合子(int1)的丰度.结果表明,共分离出的522株葡萄球菌和543株假单胞菌,约84%的菌株对所测试的抗生素具有耐药性,多重耐药率达到68%以上,MRI指数平均为0.22,与某些环境中人源或动物源细菌耐药水平相当,表明人工湿地基质土著菌具有较高水平的耐药性;两种土著菌对氨苄西林和复方新诺明的耐药率较高,四环素、庆大霉素和环丙沙星的耐药率均极低(3%),而对头孢他啶和氯霉素的耐药性呈现差别.湿地基质中int1基因的浓度为1.14×105~5.66×105copies·g-1,其相对丰度为0.54%~3.68%.季节和湿地工艺对细菌耐药和整合酶基因分布有较大影响.夏季2种细菌的抗生素耐药率、多重耐药指数和int1丰度均显著高于冬季;下行垂直流湿地中的抗生素耐药率、多重耐药指数(MRI)最高,而在水平潜流湿地中int1丰度最高.研究表明人工湿地基质的土著菌长期暴露在一定浓度抗生素和耐药肠道菌的生活污水环境下获得了耐药性,人工湿地中抗生素耐药菌和耐药基因的污染及环境风险不容忽视.     

1株对叔丁基邻苯二酚降解菌的筛选鉴定及响应面法优化其降解

从某化工厂污水处理车间活性污泥中分离、筛选到1株能以对叔丁基邻苯二酚(p-tert-Butylcatechol,TBC)为唯一碳源和能源生长的菌株YH1.经形态特征、生理生化、BIOLOG细菌自动鉴定系统和16S r DNA序列分析,鉴定菌株YH1为皱纹假单胞菌(Pseudomonas corrugate).在温度为24~36℃,p H为7.0~10.0的条件下,菌株YH1可使浓度低于500 mg·L-1的TBC降解率达到82%以上.运用单因素实验初步确定TBC降解的最适外加碳源和氮源分别为蔗糖和胰蛋白胨,最适温度为30℃,最适初始p H为7.0,最适接种量为2%.为了提高降解率,首先利用Plackett-Burman实验设计评估并筛选出影响TBC降解的3个关键因素:蔗糖、胰蛋白胨、初始p H.用最陡爬坡实验逼近以上3个因子的最大响应区域,采用Box-Behnken实验设计及响应面法分析,确定其最优降解条件为蔗糖浓度3%(ρ)、胰蛋白胨浓度1.44%(ρ)、TBC浓度400 mg·L-1、初始p H值8.12、接种量2.97%(φ)、温度30℃、培养时间96 h,在此条件下TBC降解率可达98.21%.TBC降解酶活性及酶定域实验表明,菌株YH1相关降解酶为胞内酶,且TBC可诱导邻苯二酚1,2双加氧酶(C12O)的合成.通过降解酶特异性引物从菌株YH1扩增得到C12O基因片段,经质粒检测和消除实验发现菌株YH1相关降解基因位于质粒上.此外,菌株YH1能耐受高浓度Na Cl和多种重金属离子,对多种抗生素具有抗性.研究结果为有效处理复杂工业废水提供了理论基础.     

三氯乙烯好氧共代谢降解菌鉴定和降解特性研究

由加油站附近污染土壤分离到一株好氧共代谢降解三氯乙烯的菌株Em-1,对其进行了形态学、生理生化和分子鉴定,表明为假单胞菌属。该菌可以利用甲苯为唯一碳源生长,可以以甲苯为生长底物降解三氯乙烯。对Em-1在甲苯中的生长曲线进行了分析,发现经过活化的菌株在甲苯培养基中8 h左右进入对数生长期。在摇瓶水平上进行了连续降解实验,表明甲苯经过24 h即消耗完毕,在含200 mg/L甲苯和50 mg/L三氯乙烯的无机盐培养基中,经168 h培养,三氯乙烯去除率达29.6%。为研究微生物共代谢降解三氯乙烯提供了借鉴。     

铜绿假单胞菌ZGKD2的重金属耐性机制研究

从煤矸石中分离的耐Cd2+铜绿假单胞菌(Pseudomonas aeruginosa)ZGKD2具有多种重金属耐性,研究其铁载体产生特征和重金属耐性机制对于开发土壤重金属污染修复技术具有重要意义.在牛肉膏蛋白胨培养基中分别添加200～3 000μmol.L-1的Cd2+、Cu2+、Zn2+、Ni2+、Pb2+或Mn2+等重金属,ZGKD2菌株的最大生长量随着重金属浓度的增加而降低,不同浓度重金属对ZGKD2菌株产碱能力无明显影响.ZGKD2菌株生长进入稳定期时,用0、200、600、1 000μmol.L-1的Cd2+、Cu2+、Zn2+、Ni2+或0、1 000、2 000、3 000μmol.L-1的Pb2+、Mn2+处理2 h,SOD和CAT活性随重金属浓度增加而增加.ZGKD2菌株在MSA培养基中能产生铁载体,200～1 000μmol.L-1的重金属Cd2+或Zn2+可显著诱导铁载体的产生,Ni2+和Mn2+的作用较小,Cu2+则抑制;ZGKD2菌株的产铁载体能力与重金属耐性能力相关.这些结果表明ZGKD2菌株的产碱、产铁载体特性以及抗氧化酶活性提高可能是其耐重金属的主要机制.     

铜绿假单胞菌负载Fe(III)对水中六价铬的生物吸附性能研究

采用原位沉积技术将Fe（Ⅲ）负载于铜绿假单胞菌（Pseudomonas aeruginosa,简称Pa）表面制备了Fe（Ⅲ）与细菌的复合体（Fe-Pa）,研究了Fe-Pa对水溶液中Cr（VI）的吸附特性,探讨了最佳合成条件、Fe-Pa投加量、溶液pH值、时间和Cr（VI）初始浓度等因素对Cr（VI）吸附效果的影响,同时利用SEM、FT-IR、XPS和Zeta电位对Fe-Pa进行表征分析.吸附实验结果显示,Fe（Ⅲ）浓度为600 mg·L^-1、细菌投加量为0.5 g·L^-1制备的Fe-Pa效果最佳;Fe-Pa去除Cr（VI）适宜于酸性条件进行;Fe-Pa对Cr（VI）的吸附速率较快,60 min内可达到吸附平衡,为自发的吸热吸附,且符合准二级动力学和Langmuir等温模型.表征结果表明,Fe（Ⅲ）成功地负载到铜绿假单胞菌上,为吸附Cr（VI）提供更多的活性位点,主要机制为静电吸附作用、络合作用和还原作用.经过4次吸附/再生后,Fe-Pa对Cr（VI）的吸附能力仍在72%以上,表明Fe-Pa具有较好的重复使用性.     

Antibiotic-resistant Pseudomonas aeruginosa from hospital wastewater and superficial water: Are they genetically related?

Many studies have reported the presence of antibiotic-resistant Pseudomonas aeruginosa in environmental samples such as hospital wastewater and surface water. The present study evaluated the contribution of untreated hospital wastewater to the dissemination of resistant P. aeruginosa strains in aquatic environments, through the analysis of their antibiotic susceptibility profile and genetic similarity. Wastewater samples were collected from two hospitals located in Rio Grande do Sul, RS, Brazil. Superficial water samples were collected from water bodies that received this wastewater discharge. The antibiotic susceptibility profiles of the strains were determined using the disk-diffusion technique and their genotyping was done by amplification of the Enterobacterial Repetitive Intergenic Consensus sequences (ERIC-PCR). The antibiotic resistance was higher among the hospital wastewater strains and the multiresistant phenotype was also observed only among these strains. The ERIC-PCR profiles did not reveal any genetic similarity among the P. aeruginosa strains from the wastewater and superficial water samples. On the contrary, they showed that genetically distinct populations were established in these different environments and probably that some other contamination source could be contributing to the presence of resistant strains in these water bodies.     

硝基苯降解菌的分离鉴定及降解特性

从化工厂污水处理池污泥中分离到一株能高效降解硝基苯的菌株XY-1,通过形态观察、生理生化特征和16SrDNA序列同源性分析,将该菌株鉴定为假单胞菌属(Pseudomonas sp.).该菌株能以硝基苯为唯一碳源、氮源和能源生长,硝基苯初始浓度为200 mg/L时,20 h降解率可达97%.该菌在温度25～35℃、pH 7.0～9.0范围内均能高效降解硝基苯,并且对对氯硝基苯、对氯苯胺也有良好的降解效果.测序分析表明,克隆到了该菌中的硝基苯还原酶基因,推测该菌的降解途径是硝基苯部分还原途径.图6参19     

Treatment of Olive Mill Wastewaters by Pseudomonas putida mt-2: Toxicity Assessment of Untreated and Treated Effluent

Abstract The aim of this work was to examine the performance of Pseudomonas putida mt-2 in treating olive mill wastewater (OMW) effluent after dilution with sterilized water (33%, v/v) to reduce its bactericide effect. P. putida significantly reduced the color and phenolic compounds in OMW by 75% and 66%, respectively. Dissolved chemical oxygen demand and biochemical oxygen demand removals reached 85.3% and 92.5%, respectively. Genotoxicity of OMW, before and after biodegradation with P. putida mt-2, was evaluated in vitro, using SOS chromotest, and in vivo, in mouse bone marrow, by assessing the percentage of cells bearing different chromosome aberrations. Results indicated that OMW showed a significant ability to induce DNA damage, evaluated by SOS and chromosome aberration assay systems. This toxicity was imputed to the presence of phenolic compounds of OMW. However, the toxicity of OMW was significantly reduced after 48?h of aerobic incubation with P. putida mt-2. The present study demonstrates that P...