Current molecular biologic techniques for characterizing environmental microbial community

Microbes are vital to the earth because of their enormous numbers and instinct function maintaining the natural balance. Since the microbiology was applied in environmental science and engineering more than a century ago, researchers desire for more and more information concerning the microbial spatio-temporal variations in almost every fields from contaminated soil to wastewater treatment plant (WWTP). For the past 30 years, molecular biologic techniques explored for environmental microbial community (EMC) have spanned a broad range of approaches to facilitate the researches with the assistance of computer science: faster, more accurate and more sensitive. In this feature article, we outlined several current and emerging molecular biologic techniques applied in detection of EMC, and presented and assessed in detail the application of three promising tools.     

Characterization of the dissolved organic matter in sewage effluent of sequence batch reactor: the impact of carbon source

Dissolved organic matter (DOM) transformation in sequence batch reactor (SBR) fed with carbon sources of different biodegradability was investigated. During the biologic degradation process, the low molecular weight (MW) fraction (< 1 kDa) gradually decreased, while the refractory compounds with higher aromaticity were aggregated. Size exclusion chromatography (SEC) and fluorescence of excitation emission matrices (EEM) demonstrated that more biopolymers (polysaccharides or proteins) and humic-like substances were presented in the extracellular polymeric substance (EPS) extracted from the SBR fed with sodium acetate or glucose, while the EPS from SBR fed with slowly biodegradable dissolved organic carbon (DOC) substratestarch had relatively less biopolymers. Comparing the EfOM in sewage effluent of three SBRs, the effluent from SBR fed with starch is more aromatic. Organic carbon with MW>1 kDa as well as the hydrophobic fraction in DOM gradually increased with the carbon sources changing from sodium acetate to glucose and starch. The DOC fractionation and the EEM all demonstrated that EfOM from the effluent of the SBR fed with starch contained more fulvic acid-like substances comparing with the SBR fed with sodium acetate and glucose.     

印染废水生化出水中有机污染物特性及在硫酸镁混凝过程中的去除行为

以某印染废水二级生化出水为研究对象,考察了生化出水中有机污染物中各组分含量、分子量分布特点等特性,以及各类有机物在硫酸镁混凝处理过程中的去除行为.实验结果表明,该印染废水的生化出水溶解性有机物的主要成分是疏水性物质,以溶解性有机碳（DOC）表征时占总DOC的78%,其中非酸疏水物质约占46%,而以UV254表征时约占总55%,以美国染料生产协会色度值（ADMI7.6）表征时为97%,其中以非酸疏水物质的贡献最大,达到66%,并且非酸疏水物质中不饱和双键或芳香环有机物的含量较高.生化出水中的DOC主要集中在小于1000 D的有机物上,占37%.在硫酸镁的最佳混凝条件下,可以有效地去除由大分子量的非酸疏水物质引起的色度,而对小分子量的有机物也有一定的去除效果.     

MCM - 41中孔分子筛对铜离子吸附性能的研究

以MCM-41中孔分子筛（简称MCM-41）为吸附剂,对含Cu^2＋的溶液进行了静态吸附实验。结果表明：MCM-41对Cu^2＋的吸附量较大,约为283．0mg／g;Cu^2＋的去除率随吸附液pH的增大和吸附温度的升高而增加;MCM-41对Cu^2＋的吸附性能符合Langmuir吸附方程的特征;Cu^2＋的吸附过程为自发的吸热吸附过程。     

环境分子科学与环境纳米技术

传统的分子科学和新兴的纳米技术近年来广泛地渗入和覆盖了环境科学与技术,对环境污染现象的微观过程与机理研究注入了新的活力,进一步加深对环境污染从本质上的认识,为环境保护开展更高效的技术工艺开辟了新的途径．论综合评述了环境分子科学与环境纳米技术的发展概况,并对我国该领域的研究提出一些认识和讨论意见．     

用膜结构参数模型评价溶解性有机物分子量分布对超滤膜污染的影响研究

研究了不同预处理对原水分子量分布的改变和对膜透水通量的影响,用膜污染的结构参数模型,评价了分子量分布对平均孔径和膜孔密度的影响。结果表明:(1)经过不同的预处理后,原水的分子量分布有所改变,混凝对大分子量有机物去除率较高,PAC吸附对小分子量有机物去除率较高,臭氧PAC联用预处理使大分子量有机物和小分子量有机物均有所去除。(2)分子量分布对膜通量影响较大。(3)通过试验并应用膜结构参数模型,评价了分子量分布对膜平均孔径和膜孔密度的影响,表明小分子量有机物易引起孔内吸附,大分子量有机物容易在膜面附着。     

白腐真菌酶学与分子生物学研究进展

白腐真菌对木质素降解的特异性生物学机制显示出其在复杂有机污染物降解中具有潜在应用前景。对白腐真菌酶学、自由基化学及分子生物学的国内外研究情况进行了较全面的介绍,以供国内同行参考。     

Ecological network and emergy analysis of urban metabolic systems: Model development,and a case study of four Chinese cities

Analysis of the structure and function of urban metabolic systems is an important goal of urban research. We used network pathways and network utility analysis to analyze the basic network structure of the urban metabolic system and the complex ecological relationships within the system, providing a new way to perform such research. Using four Chinese cities as examples, we developed an ecological network model of the urban metabolic system. By using network pathway analysis, we studied the changing relationships between metabolic length and the number of metabolic pathways, and between metabolic length and reachability. Based on the distribution of the number of metabolic pathways, we describe the basic structure and intercompartment relationships of the system. By using the sign distribution in the network utility matrix, we determined the ecological relationships and degree of mutualism between the compartments of the system. The basic components of the system consisted of the internal environment, the external environment, and the agricultural, industrial, and domestic sectors. With increasing metabolic length, the ecological relationships among the components of the system became more diverse, and the numbers of metabolic paths and their reachability improved. Although the basic network structure of the four cities was identical, the mutualism index differed. Beijing's mutualism index was superior to that of Shanghai, and much higher than those of Tianjin and Chongqing. By analyzing the structure and function of the urban metabolic system, we provide suggestions for optimizing the structure and adjusting the relationships, and propose methods for the application of ecological network analysis in future urban system research.     

高锰酸盐预氧化对后续生物活性炭工艺去除有机物的影响

通过测定有机物相对分子质量分布与活性炭上有机物和无机盐沉积情况,分析了高锰酸盐预氧化对后续生物活性炭工艺去除有机物的影响规律.实验结果表明,相对分子质量小于3×10³的有机物是BDOC的主要组成部分;高锰酸盐预氧化强化混凝工艺对大分子有机物(相对分子质量10×10³至0.45μm)去除的同时,使小分子有机物(0～3×10³)的含量增加,提高了活性炭进水的可生化性.与单独BAC工艺对比,高锰酸盐预氧化后使活性炭上沉积的有机物和无机盐含量分别降低了5.0mg·g^-1和4.16 mg·g^-1,减少了活性炭孔径的堵塞,延长了活性炭的使用周期.     

有机酸强化Fe(Ⅲ)还原介导的Shewanella oneidensis MR-1降解磺胺甲噁唑

在实验室条件下,研究了Shewanella oneidensis MR-1对磺胺甲噁唑（Sulfamethoxazole,SMX）的降解特性以及低分子有机酸强化Fe（Ⅲ）还原介导的S.oneidensis MR-1对SMX的降解.结果表明,S.oneidensis MR-1对不同浓度SMX的降解能力与体系中的有机酸和Fe（Ⅲ）密切相关.低浓度SMX对其生长影响不大,高浓度时细菌生长则受到抑制,进而抑制SMX的降解率.当低分子有机酸单独加入体系后,S.oneidensis MR-1对SMX的最大降解率为58.5%;Fe（Ⅲ）单独加入体系后,S.oneidensis MR-1对SMX的最大降解率为67.6%.此外,当柠檬酸和Fe（OH）₃同时加入体系后,S.oneidensis MR-1对SMX生物降解和铁还原作用促进效果最显著,培养5 d后SMX降解率为90.3%.最后,采用液相色谱-质谱联用仪（LC-MS）对SMX的降解中间产物进行了分析,推测SMX的可能降解途径是由S-N键断裂引起的.本研究以期为地下水污染场地修复提供理论依据.