秦皇岛近海养殖对潮间带微生物群落多样性的影响

潮间带微生物群落在驱动海岸带生态系统物质循环和能量流动中具有重要作用,近海养殖造成的环境问题日益凸显,但其对潮间带微生物群落结构的影响还缺乏研究。采用变性梯度凝胶电泳（DGGE）和限制性片段长度多态性（RFLP）的分子生物学技术,研究秦皇岛养殖区与旅游区潮间带沉积物中微生物多样性的差异,分析养殖区微生物的16S rRNA基因文库的组成特征。结果表明：养殖区的微生物群落结构与旅游区形成较大的差异,DGGE图谱中养殖区的特有条带主要集中于γ-变形菌纲（γ-proteobacteria）,还分布于α-变形菌纲（α-proteobacteria）,拟杆菌门（Bacteroidetes）,放线菌门（Actinobacteria）和厚壁菌门（Firmicutes）。影响潮间带微生物的群落结构的主要环境因子包括温度、盐度、pH和NO3-浓度,影响率达55.2%。对差异最大的洋河大桥南养殖区（Q1站）的微生物样品建立克隆文库分析群落结构,变形菌门（Proteobacteria）为优势菌群,占总群落的60%,其中γ-变形菌纲是主要存在的微生物纲,其余菌群包括放线菌门、拟杆菌门、蓝藻菌门（Cyanobacteria）和疣微菌门（Verrucomicrobia）的微生物。养殖区海岸带微生物群落中出现了与环境污染和赤潮密切相关的菌群,如拟杆菌门、肠杆菌属（Enterobacteriaceae）和α-变形细菌红细菌目（Roseovarius）的微生物。     

Capillary electrophoresis to analyze water-soluble oligo(hydroxyacids) issued from degraded or biodegraded aliphatic polyesters

In an attempt to increase the range of analytical techniques able to monitor ultimate degradation stages of degradable, biodegradable, and bioresorbable polymers, capillary zone electrophoresis (CZE) was used to analyze tentatively oligomers formed during thermal condensation of lactic, glycolic, anddl-3-hydroxybutyric acids. The influence of the buffer and of capillary coating are discussed in terms of electroosmotic flow. Typical analyses were first performed using a 0.1M borate buffer (pH 8.9) with anodic injection. In the case of lactic acid, seven peaks were well separated, while only three peaks were observed for glycolic acid. A more complex situation was found fordl-3-hydroxybutyric acid oligomers. The first five peaks were split. The major component of each doublet was attributed to hydroxy-terminated oligomers, whereas the satellite peaks were assigned to oligomers bearing a C=C double bond at the noncarboxylic terminus. CZE of pH-sensitive lactic acid oligomers was also performed in 0.05M phosphate buffer (pH 6.8) with cathodic injection after physical coating of the fused-silica capillary with DEAE-Dextran. The buffer-soluble fraction present in lactic acid oligomers was extracted from a dichloromethane solution. Extracts issued from different batches of lactic acid condensates gave a constant water-solubility pattern whose cutoff was at the level of the decamer. CZE was also used to monitor thein vitro aging of aqueous solutions of these water-soluble oligomers. The lactyllactic acid dimer appeared more stable than higher oligomers, thus showing that ultimate stages of the degradation did not proceed at random. These physicochemical characteristics were used to complement the degradation pathway based on diffusion of oligomers duringin vitro aging of large size lactic acid plates made by compression molding. CZE data showed that lactic acid was the only component which was released in the aqueous medium during degradation.Presented by C.B. at the 4th International Workshop on Biodegradable Plastics and Polymers, October 11–14, 1995, Durham, NH, USA.     

Evaluation of a fetus at risk for dihydropteridine reductase deficiency by direct mutation analysis using denaturing gradient gel electrophoresis

Dihydropteridine reductase (DHPR) is an enzyme involved in the recycling of tetrahydrobiopterin (BH₄), which is an obligate co-factor of the aromatic amino acid hydroxylases. DHPR deficiency is a rare, autosomal recessive disorder caused by mutations in the QDPR gene. DHPR-deficient patients are diagnosed by a lack of response to a low phenylalanine diet and by severe neurological symptoms. Final diagnosis is made by measurements of neurotransmitters and pterin metabolites in cerebrospinal fluid (CSF) and urine, in addition to DHPR enzyme activity, which can be assessed in whole red blood cells. Treatment of DHPR deficiency can be difficult and the outcome is not always satisfying, even if all treatment strategies are followed. Therefore prenatal diagnosis is of great importance in affected families. Prenatal diagnosis is possible by measuring DHPR activity in different cell types but this is time consuming. More than 25 different mutations have to date been identified in the QDPR gene and direct identification of a mutation in a fetus would be easy and rapid. We have developed a method based on denaturing gradient gel electrophoresis (DGGE) for the analysis of the QDPR gene. The method is useful for rapid and simultaneous scanning of all exons and flanking intronic sequences of the QDPR gene. We describe the first prenatal diagnosis conducted using this method. Copyright © 2001 John Wiley & Sons, Ltd.     

Characterization of depth-related microbial communities in lake sediment by denaturing gradient gel electrophoresis of amplified 16S rRNA fragments

The characterization of microbial communities of different depth sediment samples was examined by a culture-independent method and compared with physicochemical parameters, those are organic matter （OM）, total nitrogen （TN）, total phosphorus （TP）, pH and redox potential （Eh）. Total genomic DNA was extracted from samples derived from different depths. After they were amplified with the GC-341 f/907r primer sets of partial bacterial 16S rRNA genes, the products were separated by denaturing gradient gel electrophoresis （DGGE）. The profile of DGGE fingerprints of different depth sediment samples revealed that the community structure remained relatively stable along the entire 45 cm sediment core, however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. The principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into two groups, which were located 0-20 cm and 21-45 cm, respectively. The sequencing dominant bands demonstrated that the major phylogenetic groups identified by DGGE belonged to Bacillus, Bacterium, Brevibacillus, Exiguobacterium, γ-Proteobacterium, Acinetobacter sp. and some uncultured or unidentified bacteria. The results indicated the existence of highly diverse bacterial community in the lake sediment core.     

脱氮副球菌W12降解吡啶的影响因素及其赋存质粒特性

从实验室的废水生物处理反应器内的活性污泥样本,筛选出来一株以吡啶为唯一碳、氮源的脱氮副球菌(Paracoccus denitrificans),命名为W12;研究了温度、pH值、吡啶初始浓度和投菌量对W12降解吡啶的影响.结果显示,在试验温度范围内高温有利于W12降解吡啶;同时W12降解吡啶的最适pH值范围在7-9;吡啶初始浓度越大降解时间越长,且投菌量越大吡啶降解越快.此外还研究了W12菌上赋存的质粒特性.脉冲场试验表明,W12菌上2个质粒的大小分别为169 kb和182 kb,并通过质粒消除试验证实了质粒参与了编码吡啶降解基因.     

Diversity of methanotrophs in Zoige wetland soils under both anaerobic and aerobic conditions

Zoige wetland is one of the most important methane emission centers in China. The oxidation of methane in the wetland a ects global warming, soil ecology and atmospheric chemistry. Despite their global significance, microorganisms that consume methane in Zoige wetland remain poorly characterized. In this study, we investigated methanotrophs diversity in soil samples from both anaerobic site and aerobic site in Zoige wetland using pmoA gene as a molecular marker. The cloning library was constructed according to the pmoA sequences detected. Four clusters of methanotrophs were detected. The phylogenetic tree showed that all four clusters detected were a liated to type I methanotrophs. Two novel clusters (cluster 1, cluster 2) were found to relate to none of the recognized genera of methanotrophs. These clusters have no cultured representatives and reveal an ecological adaptation of particular uncultured methanotrophs in Zoige wetland. Two clusters were belonging to Methylobacter and Methylococcus separately. Denaturing gradient gel electrophoresis gel bands pattern retrieved from these two samples revealed that the community compositions of anaerobic soil and aerobic soil were di erent from each other while anaerobic soil showed a higher metanotrophs diversity. Real-time PCR assays of the two samples demonstrated that aerobic soil sample in Zoige wetland was 1.5 times as much copy numbers as anaerobic soil. These data illustrated that methanotrophs are a group of microorganisms influence the methane consumption in Zoige wetland.     

气-水两相砂介质中饱和度-毛细压力关系与水位波动之间的响应

利用时域反射仪（TDR）与微型张力计（T5）联用装置,测定气-水两相砂介质中因水位波动产生的连续干燥与湿润循环过程中饱和度-毛细压力（S-p）关系曲线.同时,研究了多重水位波动对S-p关系曲线、孔隙流体运移的滞后性及空气剩余饱和度的作用.结果表明,TDR、T5和数据自动采集器联用装置可较准确测量出气-水两相条件下S-p关系的动态变化.同一介质中不同干燥过程的侵入压值比较接近,与干燥过程的初始水饱和度无关;而干燥或湿润过程的S-p关系曲线和滞后程度则与其初始水饱和度密切相关.在特定的干燥和湿润循环过程中,初始水饱和度大小对空气剩余饱和度的值影响不大,用于预测非湿润相流体剩余饱和度的Land的假设需要修正.本研究结果对进一步研究水位波动条件下地下有机污染物运移具有借鉴作用,可为修正NAPL Simulator 提供实验依据.     

MBR和CAS工艺污泥在贫营养培养条件下的微生物群落结构研究

采用聚合酶链式-变性梯度凝胶电泳（PCR-DGGE）技术,研究了膜生物反应器（MBR）和传统活性污泥工艺（CAS）反应器中微生物在贫营养条件下的总细菌群落结构.结果表明,在培养过程中,污泥的微生物种群经历了一个比较明显的变化过程,且以CAS污泥微生物种群的变化更为明显,演替过程中既有原始优势种群的消亡,又有新的优势种群...     

Effect of ultrasonic pretreatment on anaerobic digestion and its sludge dewaterability

To investigate the effect of ultrasonic pretreatment on anaerobic digestion and sludge dewaterability and further to probe into the influencing factors on sludge dewaterability, sludge flocs were stratified into four fractions: (1) slime; (2) loosely bound extracellular polymeric substances (LB-EPS); (3) tightly bound EPS (TB-EPS); and (4) EPS-free pellets. The results showed that ultrasonic pretreatment increased the anaerobic digestion efficiency by 7%–8%. Anaerobic digestion without ultrasonic pretreatment deteriorated the sludge dewaterability, with the capillary suction time (CST) increased from 1.42 to 47.3 (sec L)/g-TSS. The application of ultrasonic pretreatment firstly deteriorated the sludge dewaterability (normalized CST increased to 44.4 (sec L)/g-TSS), while subsequent anaerobic digestion offset this effect and ultimately decreased the normalized CST to 23.2 (sec L)/g-TSS. The dewaterability of unsonicated sludge correlated with protein (p = 0.003) and polysaccharide (p = 0.004) concentrations in the slime fraction, while that of sonicated sludge correlated with protein concentrations in the slime and LB-EPS fractions (p < 0.05). Fluorescent excitationemission matrix analysis showed that the fluorescence matters in the LB-EPS fraction significantly correlated with sludge dewaterability during anarobic digestion.     

气相色谱法测定工作场所空气中的二甲基甲酰胺

针对毛细管柱恒温分析时色谱峰裂分和定量重复性差的问题,对色谱分析条件进行了改进,建立了不分流进样程序升温的二甲基甲酰胺气相色谱测定方法提高了柱效和样品分析的准确度,降低了检出限(检出限为0.3μg/mL)。