Degradation of Polyethylene and Nylon-66 by the Laccase-Mediator System

We investigated whether the laccase-mediator system (LMS) with 1-hydroxybenzotriazole (HBT) as a mediator could degrade high-molecular-weight polyethylene and nylon-66 membranes. The LMS markedly reduced the elongation and tensile strength of these membranes. After 3 days of treatment with the LMS, the M _w of polyethylene decreased from 242,000 to 28,300, and that of nylon-66 from 79,300 to 14,700. The LMS also decreased the polydispersity (M _w/M _n) of polyethylene and nylon-66. Furthermore, these reductions in elongation, tensile strength, and molecular weight were accompanied by morphological disintegration of the polyethylene and nylon-66 membranes. These results strongly suggest that the LMS with HBT can effectively degrade polyethylene and nylon-66.     

Achromobacter xylosoxidans NS12的分离和对硝基苯酚的降解

通过富集培养,从红树林底泥中分离出6株硝基苯酚降解菌,其中Achromobacter xylosoxidans NS12在好氧条件下可耐受小于1.8 mmol/L的邻硝基苯酚（ONP）或3.0 mmol/L的对硝基苯酚（PNP）,能以PNP和ONP作为唯一碳源、能源和氮源生长并将其完全矿化, 但该菌不能利用间硝基苯酚（MNP）作为唯一碳源和氮源生长.研究发现A. xylosoxidans NS12在降解PNP和ONP组成的混合底物时,PNP的存在可抑制ONP的降解,同时ONP的存在也抑制PNP的降解.此外,在利用PNP和ONP的混合底物时,NS12转化PNP的速率显著地高于转化ONP的速率.红树林底泥中固有的细菌对PNP和ONP具有高效降解作用.     

久效磷降解菌的分离及其酶促降解特性研究

从某农药厂废水处理池的污泥中分离到1株久效磷高效降解菌株M-1,经过对其形态特征、生理生化、以及16S rDNA序列分析,该菌株初步鉴定为Paracoccus sp..M-1能以久效磷作为唯一碳源生长,24 h对100 mg·L^-1久效磷的降解效率为92.47%.久效磷降解酶定域表达试验表明该酶为胞内酶,组成表达.久效磷酶促降解的最适反应pH为8.0,最适反应温度为25 ℃;其米氏常数（K_m）为0.29 μmol·mL^-1,最大降解速率(V_max)为682.12 μmol·(min·mg)^-1.久效磷降解酶热稳定性差,碱性条件下能够保持较高降解活性.     

毒死蜱降解细菌XZ-3的分离及降解特性研究

从某农药厂排污口的污泥中采样,经驯化富集后筛选到1株能高效降解毒死蜱的细菌XZ-3,经过对其形态、生理生化特征及16S rDNA的分析,鉴定该菌株为节杆菌属（Arthrobactersp.）.测定了不同碳源、pH、温度及毒死蜱浓度对细菌降解能力和生长量的影响,以培养液在波长400 nm下的光密度值表示细菌生长量,液体介质中毒死蜱的提取采用漩涡振荡提取法,提取溶剂为石油醚,毒死蜱的测定采用紫外分光光度法.结果表明,该菌株24 h内对100 mg·L^-1毒死蜱的降解率高达86.8%;在外加碳源浓度为0.3%时降解率最大;细菌的生长量随着外加碳源浓度的升高而增加;pH在偏酸和偏碱性的条件下降解率较大,pH 9.0时达到最大,细菌的生长量在pH 8.0～10.0偏碱性的条件下较大;在毒死蜱浓度为100　mg·L^-1时降解率最大,该菌具有较强的抗药性,当毒死蜱浓度达到1?000　mg·L^-1时仍能生长,细菌的生长量在800　mg·L^-1时达到最大,绝对去除量随毒死蜱浓度的提高而增加;细菌的生长和降解需要适宜的温度,30℃培养时,降解率和生长量最大.本研究提出了细菌XZ-3生长和降解毒死蜱的最佳培养条件,可为农药污染治理及生产污水处理提供理论依据.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Dynamic changes in microbial activity and community structure during biodegradation of petroleum compounds： A laboratory experiment

With 110-d incubation experiment in laboratory,the responses of microbial quantity,soil enzymatic activity,and bacterial community structure to different amounts of diesel fuel amendments were studied to reveal whether certain biological and biochemical characteristics could serve as reliable indicators of petroleum hydrocarbon contamination in meadow-brown soil,and use these indicators to evaluate the actual ecological impacts of 50-year petroleum-refining wastewater irrigation on soil function in Sbenfu irrigation area.Results showed that amendments of≤1000 mg/kg diesel fuel stimulated the growth of aerobic beterotrophic bacteria,and increased the activity of soil dehydrogenase,hydrogenperoxidase,polypbenol oxidase and substrate-induced respiration.Soil bacterial diversity decreased slightly during the first 15 d of incubation and recovered to the control level on day 30.The significant decrease of the colony forming units of soil actinomyces and filamentous fungi can be taken as the sensitive biological indicators of petroleum contamination when soil was amended with≥5000 mg/kg diesel fuel.The sharp decrease in urease activity was recommended as the most sensitive biochemical indicator of heavy diesel fuel contamination.The shifts in community structure to a community documented by Sphingomonadaceae withinα-subgroup of Proteobacteria could be served as a sensitive and precise indicator of diesel fuel contamination.Based on the results described in this paper,the soil function in Shenfu irrigation area was disturbed to some extent.     

浓度对高固体污泥热水解特性及流动性的影响

考察固体浓度为7%、9%和13%的高固体污泥的热水解特性,通过生化甲烷潜能(BMP)试验,考察热水解处理高固体污泥厌氧消化性能的变化,通过流变性试验,考察污泥浓度与流动性的关系.结果表明,随着热水解时间延长,污泥中有机物溶解率增大,30min后变化趋于平缓.水解效率受固体浓度影响,浓度7%污泥的有机物溶解率高于9%和13%的污泥.170℃热水解30min,7%的污泥SS、VSS和COD的溶解率分别为43%、47%和42%,VFA/SCOD为20.2%.热水解污泥厌氧消化性能提高,相比未经热水解处理的污泥,浓度7%、9%和13%的污泥在170℃热水解30min后产气量分别增加了44%、27%和9%,沼气产率分别增加了63%、74%和37%.固体浓度对污泥厌氧消化性能的影响显著,浓度9%的污泥产气中甲烷含量以及沼气产率均高于7%、13%的污泥.固体浓度9%时,污泥屈服应力增长缓慢,固体浓度大于9%时,污泥屈服应力增长快速,流动性急剧下降.     

Xanthobacter flavus DT8降解二噁烷的特性研究

对上海某医药厂污水站好氧池的活性污泥进行长期驯化,分离到1株能以二噁烷为唯一碳源和能源生长的菌株DT8.经生理生化、脂肪酸鉴定和16S rRNA序列分析,确定该菌株为黄黄色杆菌DT8(Xanthobacter flavus DT8).序批实验表明X.flavus DT8可于48 h内完全降解100 mg.L-1二噁烷,并可实现污染物的矿化.随着生物量的增加,该降解过程的细胞得率(以二噁烷计)为0.62 g.g-1,能量消耗系数(δe)为1.00,表明X.flavus DT8代谢二噁烷消耗的能量较少.研究不同温度、pH和营养条件对二噁烷降解的影响,发现二噁烷降解较适宜的温度和初始pH分别为34℃和7.0;在贫营养条件下,即无机盐培养基稀释100倍时,100 mg.L-1二噁烷于48 h的降解率达到65.6%.对X.flavus DT8降解二噁烷可能的诱导机制进行初步研究,结果表明X.flavus DT8对二噁烷的降解不需要经历诱导的过程.本研究揭示了X.flavus DT8直接代谢二噁烷的特性,为生物法净化含二噁烷废水及废气的工程应用奠定了基础.     

原油降解中微生物群落的16S rDNA-PCR-DGGE分析

为对原油降解过程中微生物群落结构的变化,本文采用直接向原油中加入营养物刺激的方法,获得原油降解菌体系。提取不同培养时间条件下降解菌体系的总DNA,并以之为模板采用PCR-DGGE技术研究了在原油降解过程中微生物群落的组成,结果表明,随着培养时间的不同,微生物的群落结构表现出差异,随着时间的变化其微生物群落也会发生改变。回收了DGGE图谱中的18个条带,测序结果经过Blast比对表明其中10个条带代表的细菌是不可培养的,显示了DGGE技术的优越性。同时采用气相色谱技术对降解过程中的原油烃的变化进行了分析,结果显示原油烃类组分会随着降解菌多样性的变化而发生变化,降解菌体系表现出了其对烷烃类物质的降解能力。     

脱氮副球菌W12在游离生长与附着生长条件下对吡啶去除作用的研究

分离到1株吡啶降解菌——脱氮副球菌(Paracoccus denitrificans W12),将其附着生长于颗粒活性竹炭(ABC)制备成生物活性竹炭(BABC),分别以游离菌和固着菌开展对水中吡啶的去除实验.结果表明,0.31g·L-1游离态W12菌可在26.5～48.9h内将48.70～1399mg·L-1的吡啶完全降解;附着于ABC的W12菌不仅保持其降解能力,而且BABC通过吸附与降解的协同作用更高效地去除吡啶,当温度为35℃,BABC投加量为10.0g·L-1时,692.2mg·L-1的吡啶在前3.6h主要通过吸附作用降低52%,其后主要通过生物降解作用至23.7h被基本去除,随着BABC投加量和处理批次的增加,吡啶去除效率显著提高.研究进一步从微观结构上对BABC去除水中吡啶的协同作用机制进行了探讨.