降解2,4-二氯酚微生物的分离及其2,4-二氯酚羟化酶基因的克隆和表达

从土壤中分离到一株降解2,4-二氯酚能力较强的细菌菌株GT241-1,经鉴定该菌株属于假单胞菌属。菌株GT241-1在最适条件下能在48h内将90mg/L的2,4-DCP降解91%,能利用2,4-二氯酚、2,4-二氯苯氧乙酸、苯甲酸和儿茶酚为唯一碳源生长。采用Southern杂交对2,4-二氯酚羟化酶基因（dcpA）定位后构建基因组文库,再用斑点杂交筛选目的转化子,克隆了该菌株的dcpA。序列测定得知含dcpA的亚克隆片段全长2389bp,其中dcpA基因编码区1797bp。核苷酸和氨基酸序列分析表明,dcpA与已在GenBank登记的相关基因有一定的差异。dcpA基因能够在大肠杆菌转化子中成功地表达有生物活性的酶。     

固定化白腐真菌降解水溶液中2,4-二氯酚的研究

研究固定化黄孢原毛平革菌对水溶液中2,4-二氯酚（2,4-DCP）的降解效果,探讨固定化黄孢原毛平革菌处理水溶液中氯酚类污染物的可行性．结果表明,采用固定化方法处理的白腐真菌．其产酶稳定性及酶活均比游离态白腐真菌有显著提高．2,4-DCP降解效果受固定化孢子接种量、pH值、摇床转速、2,4-DCP的初始浓度和表面活性剂浓度的影响．当pH为4．5,摇床转速180r／min,培养基含有1％的Tween 80,2,4-DCP初始浓度为40mg／L时,加入10mL固定化白腐真菌孢子,2,4-DCP去除效果最好．     

球形红细菌厌氧降解2,4-二硝基甲苯

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30 °C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始pH 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

零价铁对2,4-二氯酚生物还原脱氯的影响研究

采用间歇试验,接种驯化两月的厌氧混合微生物,考察厌氧体系中添加零价铁（Fe^0）对2,4-二氯酚（2,4-DCP）生物还原脱氯效果的影响,并对影响“Fe^O＋微生物”体系的一些因素进行了探索。结果显示：与零价铁或微生物的单独作用相比,“Fe^O＋微生物”体系能够有效促进2,4-DCP的脱氯反应,最佳Fe^O投加量和微生物接种量分别为0.5g／L和376.2mgVSS／L;初始pH=8.0对2,4-DCP的转化效果最好,偏酸性环境不利于污染物转化;微生物接种量与铁用量之间有一适宜比例,一定范围内增加微生物接种量可催生出更多可降解污染物的酶或酶系,提高2,4-DCP的降解效果。     

零价铁对2,4-二氯酚生物还原脱氯的影响研究

采用间歇试验, 接种驯化两月的厌氧混合微生物, 考察厌氧体系中添加零价铁(Fe0)对2,4-二氯酚(2,4-DCP)生物还原脱氯效果的影响, 并对影响“Fe0+微生物”体系的一些因素进行了探索。结果显示：与零价铁或微生物的单独作用相比, “Fe0+微生物”体系能够有效促进2,4-DCP的脱氯反应, 最佳Fe0投加量和微生物接种量分别为0.5 g/L和376.2 mgVSS/L; 初始pH = 8.0对2,4-DCP的转化效果最好, 偏酸性环境不利于污染物转化; 微生物接种量与铁用量之间有一适宜比例, 一定范围内增加微生物接种量可催生出更多可降解污染物的酶或酶系, 提高2,4-DCP的降解效果。     

降解2,6-二叔丁基苯酚菌种的驯化与鉴定

从腈纶废水处理构筑物中分离筛选到1株高效降解2,6-二叔丁基苯酚的菌株M-Z-8,对其进行了驯化试验以及生理生化、分子生物学鉴定。结果表明,经过驯化后的M-Z-8在100．0mg／L的初始浓度下其降解率在12d可达到51．6％,比未经驯化菌种对底物的降解率要高出12％。扫描电镜观察到菌株形态为杆状,极生鞭毛。将M-Z-8的16SrDNA序列进行核苷酸同源性比较,与气单胞菌种属的16SrDNA核苷酸序列同源性均在97％以上。经生理生化以及分子生物学鉴定M-Z-8为气单胞菌。     

Arthrobacter sp.2PR降解2-羟基吡啶动力学及降解特性研究

从辽河口石油污染土壤中筛选到一株能够以2-羟基吡啶作为唯一碳源、氮源和能源进行生长的菌株2PR,基于形态学观察、16S rRNA基因序列分析鉴定菌株2PR属于节杆菌属(Arthrobacter)。菌株2PR生长和降解2-羟基吡啶的最适条件是30℃,pH为7.0。当2-羟基吡啶初始浓度为6.0mg/ml时,120h菌株2PR对2-羟基吡啶的降解效率为94.48%,初始2-羟基吡啶浓度为8.0mg/ml时,156h的降解效率为89.21%。对2-羟基吡啶降解动力学过程进行模拟,结果显示菌株2PR生长和降解过程符合logisitic模型,该模型为环境中2-羟基吡啶的生物降解提供了理论参考。休止细胞反应和中间代谢产物检测表明,菌株2PR在降解2-羟基吡啶的过程中生成了蓝色化合物4,5,4',5'-tetrahydroxy-3,3'-diazadiphenoquinone-(2,2')。推测该菌株降解2-羟基吡啶的途径可能是首先由双加氧酶催化生成2,3,6-三羟基吡啶,后者会自发形成蓝色中间代谢产物,2,3,6-三羟基吡啶发生开环反应,最终被完全降解。菌株2PR是已报道菌株中2-羟基吡啶耐受能力和降解能力最强的菌株,在污染物生物修复方面具有广阔的应用前景。     

石油污染土壤中苯酚降解菌ad049的鉴定及降解特性

以苯酚为唯一碳源,采用富集培养方法,从陕北靖边油田污染土壤中分离获得1株苯酚高效降解菌(ad049),对菌株进行形态观察、生理生化检验及16S rDNA序列分析,确定该菌株为红球菌(Rhodococcus)。采用摇瓶振荡培养方法,研究了接种量、pH值、温度和底物浓度对ad049生长量和苯酚降解率的影响,同时对该菌株脱氢酶和邻苯二酚双加氧酶活性进行了测定。结果表明,ad049具有较强的苯酚降解能力;在苯酚浓度1000 mg/L,温度35℃,pH值8,接种量5%的培养条件下,反应24 h后,苯酚降解率达99%以上,且整个降解过程符合零级动力学方程,速率常数k_0=41.51,相关系数R~2=0.96。通过邻苯二酚双加氧酶活性的测定,推测出该菌株降解苯酚的途径可能是以邻苯二酚1,2双加氧酶为主要途径进行邻位开环,辅以邻苯二酚2,3双加氧酶进行间位开环。     

NBPT在土壤中的降解及其影响因子

采用实验室培养方法研究了NBPT在土壤中的降解动态。结果表明,在未灭菌的土壤中,NBPT的半衰期为7.2~7.6 d,远远小于在灭菌土壤中22.4 d的半衰期;随着环境温度增高(20℃上升至30℃),NBPT降解速度略有提升(半衰期由7.6 d缩短至6.5 d);NBPT在黑暗条件下降解半衰期为4.5 d,而在光照条件下的半衰期为5.9 d。可见,几种试验因子对土壤中NBPT的降解均有不同程度的影响。其中土壤微生物是影响NBPT降解的主要因素,有利于土壤中微生物生长的环境因素,如偏酸的土壤,对土壤中NBPT的降解有促进作用。而葡萄糖则可能因为增加了土壤颗粒的团聚性及其还原性能,增加了土壤对NBPT的吸附而抑制了NBPT的降解。     

一株降解O,O-二甲基-O-(2,2-二氯乙烯基)磷酸酯的土壤微生物的分离与鉴定(英文)

目的:有机磷农药和杀虫剂广泛应用于众多国内和国外生产的,其数量已超过100种。大量使用的有机磷农药会增加农业生产,而且还造成了不可估量的环境污染。研究降解敌敌畏的微生物,为微生物以降低产品敌敌畏农药残留,恢复敌敌畏污染土壤中的研究奠定基础。方法:本文从种植蔬菜的温室大棚的土壤中分离了一株降解O,O-二甲基-O-(2,2-二氯乙烯基)磷酸酯(敌敌畏)的细菌,根据该菌的形态学、生理生化特征及16S rDNA序列比对。结果:该菌鉴定为荧光假单胞菌(菌株P)。该菌的最适生长温度为27℃,其培养基的最适初始pH为7.0,4天内该菌可将培养液中61.24%的降解。结论:本实验从蔬菜大棚的土样中筛选出一株能降解敌敌畏的菌株,并鉴定为荧光假单胞菌。本研究将为基于微生物以降低产品敌敌畏农药残留,恢复敌敌畏污染土壤中的研究打下基础。     

Purification and properties of a plasmid-encoded 2,4-dichlorophenol hydroxylase

2,4-Dichlorophenol hydroxylase, an enzyme involved in the bacterial degradation of the herbicide 2,4-dichlorophenoxyacetate (2,4-D) was purified from two bacterial strains that harbored the same 2,4-D plasmid, pJP4. The purified enzymes (Mr 224 000) from the two transconjugants were indistinguishable; they contained FAD and were composed of non-identical subunits, Mr 67 000 and 45 000, respectively. Various substituted phenols were hydroxylated, using either NADH or NADPH. The amino acid composition of the native enzyme was determined.     

Anaerobic degradation of tetrachlorobisphenol-A in river sediment

This study investigated the anaerobic degradation of tetrachlorobisphenol-A (TCBPA) in sediment samples collected at three sites along the Erren River in southern Taiwan. TCBPA anaerobic degradation half-lives (t_1/2) in the sediment were 12.6, 16.9 and 21.7 d at concentrations of 50, 100, and 250 ??g g⁻¹, respectively. TCBPA (50 ??g g⁻¹) anaerobic degradation half-lives (t_1/2) in the sediment were 10.1, 11.8, 11.0, 11.6, 10.8, 9.1, 8.5, 18.2, 19.3, and 16.1 d by the addition of yeast extract (5 mg l⁻¹), cellulose (0.96 mg l⁻¹), sodium chloride (1%), brij 30 (130 mg l⁻¹), brij 35 (43 mg l⁻¹), rhamnolipid (55 ??M), surfactin (91 ??M), phthalic esters (2 mg l⁻¹), nonylphenol (2 mg l⁻¹), and heavy metals (2 mg l⁻¹), respectively. The degradation rate of TCBPA was enhanced by the addition of yeast extract, cellulose, sodium chloride, brij 30, brij 35, rhamnolipid, or surfactin. However, it was inhibited by the addition of phthalic esters, nonylphenol, or heavy metals. Also noted was the presence of dichlorobisphenol-A and bisphenol-A, two intermediate products resulting from the anaerobic degradation of TCBPA accumulated in the sediments.     

Degradation of dissolved and sorbed 2,4-dichlorophenol in soil columns by suspended and sorbed bacteria

The influence of sorption of bacteria, as well as 2,4-dichlorophenol (2,4-DCP), on themineralization of 100 g l^-1 of the organic compound was examined in an aquifer material under advective flow conditions (column displacement technique). The study was designed to distinguish the rates and extent of biodegradation of the sorbed and the dissolved trace organic and the contribution of sorbed and suspended bacteria to the degradation. The degradation of dissolved 2,4-DCP was significantly faster thanthe degradation of the same compound sorbed to the solids, and suspended bacteriadegraded the dissolved compound at a higher rate than sorbed bacteria, also on a percell basis. The suspended bacteria degraded 8–12% of the added dissolved 2,4-DCP, while sorbed bacteria made a smaller contribution by degrading about 5% of sorbed 2,4-DCP. No degradation was seen with sorbed 2,4-DCP and suspended bacteria, and a marginal contribution was made by sorbed bacteria on the degradation of dissolved 2,4-DCP (<0.4%).     

Biodegradation of 2,4-dichlorophenol in the presence of volatile organic compounds in soils under different vegetation types

It has been suggested that monoterpenes emitted within the soil profile, either by roots or by decaying biomass, may enhance the biodegradation of organic pollutants. The aim of this study was to evaluate the effect of biogenic volatile organic compounds (VOCs) on the catabolism of 2,4-dichlorophenol in soils. Soils were collected from areas surrounding monoterpene (woodland) and nonmonoterpene (grassland)-emitting vegetation types. Soils were spiked with [UL-¹⁴C] 2,4-dichlorophenol at 10 mg kg⁻¹ and amended with α-pinene, p -cymene or a mix of monoterpenes (α-pinene, limonene and p -cymene in 1 : 1 : 1 ratio). The effects of monoterpene addition on the catabolism of [UL-¹⁴C] 2,4-dichlorophenol to ¹⁴CO₂ by indigenous soil microbial communities were assessed in freshly spiked and 4-week-aged soils. It was found that aged woodland soils exhibited a higher level of [UL-¹⁴C] 2,4-dichlorophenol degradation, which was subsequently enhanced by the addition of monoterpenes ( P <0.001), with the VOC mix and α-pinene amendments showing increased [UL-¹⁴C] 2,4-dichlorophenol catabolism. This study supports claims that the addition of biogenic VOCs to soils enhances the degradation of xenobiotic contaminants.     

Ecosystems patterns and dynamics in Haihe river basin

Research on ecosystems patterns and dynamics is critical for understanding the regional problems of resources and environment. In this study, based on the technology of RS and GIS, the composition, patterns and dynamics of the ecosystems in Haihe river basin during 1990–2005 were analyzed using landscape indices including the area of average patches, aggregation index and Shannon–Weaver diversity index. According to the development situation of economy and society in Haihe river basin, some driving factors for dynamics of ecosystems patterns were concluded based on correlation analysis. Results showed that the ecosystems patterns in Haihe river basin changed greatly from 1990 to 2005. The area of urban and grassland increased, but farmland, forest and wetland decreased. As for landscape indices, the area of average patches, value of aggregation index, clump index and diversity index all increased, indicating the trend of evenness for the whole ecosystems. Growth of population, economy growth together with urbanization and policy were the main driving factors for dynamics of ecosystem pattern in this basin.     

Ecosystems patterns and dynamics in Haihe river basin

Research on ecosystems patterns and dynamics is critical for understanding the regional problems of resources and environment. In this study, based on the technology of RS and GIS, the composition, patterns and dynamics of the ecosystems in Haihe river basin during 1990–2005 were analyzed using landscape indices including the area of average patches, aggregation index and Shannon–Weaver diversity index. According to the development situation of economy and society in Haihe river basin, some driving factors for dynamics of ecosystems patterns were concluded based on correlation analysis. Results showed that the ecosystems patterns in Haihe river basin changed greatly from 1990 to 2005. The area of urban and grassland increased, but farmland, forest and wetland decreased. As for landscape indices, the area of average patches, value of aggregation index, clump index and diversity index all increased, indicating the trend of evenness for the whole ecosystems. Growth of population, economy growth together with urbanization and policy were the main driving factors for dynamics of ecosystem pattern in this basin.     

Sediment dynamics and estuarine circulation in the turbidity maximum of the Elbe river

Data are presented from several campaigns concerning to the residual transport of water, salt and suspended particulate matter (SPM) at different depths and at different longitudinal and cross-sectional locations in the Elbe Estuary, Northern Germany. The intratidal behaviour of SPM is analysed and explained in terms of cyclic settling and resuspension. Superimposed on these local processes are advective horizontal transports of water and SPM in different vertical layers. Tidally averaged horizontal fluxes of salinity and SPM have been calculated at different depths. For the most part, they show upstream directed transport in the bottom layers, while in the upper water column SPM is carried towards the sea. Examples of the influence of vertical salinity gradients on SPM dynamics, of the lateral variation of residual transport of water and SPM, and the effects of a runoff peak are also presented.     

Culture-independent study of bacterial communities in tropical river sediment

Ubiquitous microbial communities in river sediments actively govern organic matter decomposition, nutrient recycling, and remediation of toxic compounds. In this study, prokaryotic diversity in two major rivers in central Thailand, the Chao Phraya (CP) and the Tha Chin (TC) distributary was investigated. Significant differences in sediment physicochemical properties, particularly silt content, were noted between the two rivers. Tagged 16S rRNA sequencing on a 454 platform showed that the sediment microbiomes were dominated by Gammaproteobacteria and sulfur/sulfate reducing Deltaproteobacteria, represented by orders Desulfobacteriales and Desulfluromonadales together with organic degraders Betaproteobacteria (orders Burkholderiales and Rhodocyclales) together with the co-existence of Bacteroidetes predominated by Sphingobacteriales. Enrichment of specific bacterial orders was found in the clayey CP and silt-rich TC sediments, including various genera with known metabolic capability on decomposition of organic matter and xenobiotic compounds. The data represent one of the pioneered works revealing heterogeneity of bacteria in river sediments in the tropics.     

Degradation of 2,4-dichlorophenol by Bacillus sp. isolated from an aeration pond in the Baikalsk pulp and paper mill (Russia)

A pure culture of 2,4-dichlorophenol (2,4-DCP)-degrading bacteria was isolated from a natural enrichment that had been adapted to chlorophenols in the aeration pond of the Baikalsk pulp and paper mill (Russia). The bacteria were identified by 16S rDNA intergenic region analysis, using PCR with universal primers. Comparative analysis of the 16S rDNA sequence (1545 bp) in the GenBank database revealed that these bacteria are related to Bacillus cereus GN1. Degradation of 2,4-DCP was studied using this culture in liquid medium under aerobic conditions, at initial concentrations of 20–560 μM 2,4-DCP. The 2,4-DCP degradation rates by B. cereus GN1 could be determined at concentrations up to 400 μM. However, higher concentrations of 2,4-DCP (560 μM) were inhibitory to cell growth.