甲氰菊酯降解菌JQL4-5的分离鉴定及降解特性研究

从农药厂废水处理池的活性污泥中分离到1株能以甲氰菊酯为唯一碳源生长的细菌,命名为JQL4-5.根据其生理生化特征和16S rDNA(GenBank Accession No.DQ177525)序列相似性分析,将该菌株鉴定为鞘氨醇单胞菌属(Sphingomonas sp.).该菌株在24h内对20 mg/L的甲氰菊酯的降解率达到99.8%.降解甲氰菊酯的最适温度为30℃,pH为7.0,降解速率与初始接种量呈正相关.酶的定域试验表明,降解甲氰菊酯的酶为胞内酶.     

降解菌CDS-1产呋喃丹水解酶的条件及酶学特征

Sphingomonas sp.CDS-1是一株呋喃丹高效降解菌.为了给利用该菌产生的酶去除环境中的呋喃丹残留提供一些理论依据,对CDS-1产生的呋喃丹水解酶粗酶进行了研究.结果表明,在LB培养基中,CDS-1产生呋喃丹水解酶的最适条件为pH6～8、30℃、培养30h;该酶在20～30℃、pH>6.0的条件下比较稳定;在pH6.5和30℃时显示最大的呋喃丹水解酶活性;大多数金属离子浓度在0.2mmol/L时对其酶活有促进作用;酶定域实验结果显示该酶为胞内酶.     

活性污泥系统中酶研究进展

细菌和原生动物在污水处理中的作用与各自的酶活性密切相关。细菌对有机质进行分解,而原生动物对污水及细菌进行澄清,活性污泥酶活性高则出水水质较好。污水中毒性物质(如重金属)对活性污泥酶活性有抑制作用,原因是重金属离子能和酶中的巯基(—SH)结合。     

农业废物堆肥中高产漆酶新菌株的分离鉴定及酶学性质研究

从农业固体废物堆肥中分离得到1株高产漆酶的新菌株,通过对其形态特征和ITS序列分析,鉴定该菌株为哈茨木霉(Hypocrea lixii).以Cu1AF和Cu2R为引物对该菌株的漆酶基因进行扩增,PCR产物回收克隆后测序得到长度为148 bp的漆酶基因片段.在液体培养条件下,菌株漆酶活力可达到67.5 U.mL-1.对该菌株的漆酶酶学性质初步研究显示:漆酶相对分子质量大约为60×103,酶反应的最适温度为35℃,最适pH为4.0;在60℃时漆酶半衰期>1 h;漆酶氧化2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐(ABTS)的米氏常数(Km)值为1.00 mmol.L-1;金属离子对酶活的影响很大,Na+、Fe2+、Fe3+、Pb2+、Zn2+对酶活都有抑制作用.该菌株有很好的应用潜力来作农业废物堆肥处理系统的强化菌剂.     

敌敌畏降解真菌的分离及其特性研究

从受过有机磷农药污染的污泥中分离到一株降解敌敌畏的真菌。经初步鉴定为木霉属,并命名为木霉FM10。该菌对敌敌畏的降解是同葡萄糖以共代谢方式进行的。葡萄糖浓度在1000μg/mL时,木霉FM10降解低地畏作用最强;敌敌畏初浓度越大降解率越低;菌株生长的最适pH为8.0,而pH9.0时,菌株降解率更高;37℃是菌株生长和降解敌敌畏的最适温度;增加接种量可以提高降解率;金属离子对所分离菌株一般表现为抑制作用。经分析,木霉FM10降解敌敌畏的酶多分布于胞外,属于分泌性酶。     

一株羽毛角蛋白降解菌的分离鉴定及特性研究

采用富集培养的方法,从广西大学家禽养殖场废弃羽毛处土样中筛选获得一株高效降解羽毛角蛋白的菌株GZD-23。经形态学、生理生化特性和16S rDNA序列分析,鉴定该菌株为枯草芽孢杆菌(Bacillus subtilis)。环境因素影响和酶学特性实验结果表明,蔗糖与蛋白胨是菌株GZD-23降解羽毛的最佳外加碳氮源,pH 8.0、温度30℃、转速100 r/min和羽毛含量20 g/L为其降解羽毛的最适反应条件。菌株GZD-23合成的角蛋白酶最适反应温度为60℃,最适pH为7.5;金属离子Cu2+、Hg2+、Fe2+、Co2+、Zn2+、Mn2+以及SDS、EDTA和高浓度TritonX-100、异丙醇和β-巯基乙醇对其酶活有不同程度抑制作用;低浓度TritonX-100、异丙醇和β-巯基乙醇对其酶活具有一定促进作用。     

拟除虫菊酯类杀虫剂的酶促降解

测定了降解菌Ａｌｃａｌｉｇｅｎｅｓ ｓｐ．ＹＦ １１粗酶液对拟除虫菊酯杀虫剂的降解性能,粗酶液降解杀灭菊酯、甲氰菊酯、氯氯菊酯、溴氰菊酯氯菊酯、三氟氯氰菊酯的最适ｐＨ分别为８．０、８．５、８．０、８．０、９．０、７．５;米氏常数分别为４１．４、１３６．８、６５．４、２２２．８、５．２、８．６７ｎｍｏｌ／ｍｌ;最适温度为３２．５℃,该粗酶液在ｐＨ５．０－１０．５均具有降解活性。     

黄杆菌P3-2的分离及降解有机磷农药的某些性质

本文介绍从农药污染严重的棉田土中分离得一株降解对硫磷能力较强的黄杆菌P3-2.该菌还可降解杀螟松、甲基对硫磷和水胺硫磷等有机磷农药.其性能稳定,在4℃下保存30天降解能力变化不大,降解对硫磷的最适pH值为8.0.最适温度为45℃.金属络合剂如邻菲罗啉等对降解能力有明显的抑制作用,铜离子有显著的激活作用,低浓度的某些有机溶剂没有抑制作用.用对硫磷作唯一碳源培养的3g湿菌体经琼脂固化后,每小时降解该农药约64mg.     

外源重金属Cu、Cd对红树林沉积物酶活性的影响

采用外源添加重金属室内恒温培养实验研究了Cu、Cd对三亚河红树林沉积物脲酶、蔗糖酶和过氧化氢酶活性的影响.结果表明,Cu能够抑制红树林沉积物脲酶和蔗糖酶活性,Cd对脲酶、蔗糖酶和过氧化氢酶活性均能产生抑制作用.Cu与Cd复合污染对脲酶和过氧化氢酶活性表现为独立作用,对蔗糖酶表现为协同作用.培养前期,重金属处理沉积物酶活性逐渐降低,后期趋于稳定.重金属对光滩沉积物酶活性的抑制效果最强,其次是林缘沉积物,对林内沉积物酶活性的抑制作用较弱.     

镍、锌、铝对羊角月芽藻(Selenastrum capricornutum)生长及酶活性影响研究

研究了不同浓度镍，锌，铝对常见绿藻羊角月芽藻生长速度，蛋白质含量，ＡＴＰ水平，葡萄糖－６－磷酸脱氢酶，酸性磷酸酶及硝酸还原酶活性的影响。结果表明３种金属离子在所试浓度范围内对羊角月芽藻的生长速度均有抑制作用，但单位藻培养物中蛋白质含量却随着金属离子浓度的增加而增加；高浓度金属离子对酶活性有明显抑制作用；藻细胞中ＡＴＰ水平随着金属离子浓度的增加而下降。     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.