西安市景观湖泊水体细菌群落结构分析与代谢功能预测

湖泊水体中细菌群落多样性及其代谢功能研究对城市景观湖泊水环境健康发展有着重要意义.以汉城湖、南湖、兴庆湖和桃花潭为研究区域,使用Illumina Nova高通量测序技术研究4个不同类型湖泊中群落组成和结构,使用冗余分析方法分析细菌群落与环境因子的相关性,采用Tax4Fun预测细菌群落的代谢功能.结果表明,不同湖泊水体细菌群落多样性各不相同,其中桃花潭α多样性最高,兴庆湖最低,同一湖泊水体的细菌群落结构有聚集趋势;4个湖泊水体的细菌优势门类相似,主要是变形菌门、拟杆菌门和放线菌门,不同之处仅在于细菌的比例;4个湖泊水体属水平细菌群落分布有较大差异;水体理化性质与细菌群落存在显著相关性,其中最关键因子为氮磷营养盐(P<0.05); Tax4Fun功能预测表明,4个湖泊水体细菌群落代谢功能相似,氨基酸代谢和碳水化合物代谢相对丰度最高,此外,其潜在的耐药性细菌污染较大以及致人类患传染性疾病可能性较大.研究结果有助于了解西安市城市湖泊水环境细菌现状,为城市湖泊治理及可持续发展提供理论依据.     

湖泊沉积物中微生物群落对天然有机质输入的响应

全球气候变化和蓝藻水华暴发造成湖泊生源、陆源天然有机质(NOM)输入显著增加,以太湖藻型湖湾为例,考察沉积物中微生物群落的活性、组成及功能对不同浓度藻源有机质(POM)和陆源腐殖酸(HA)的响应特征.三维荧光分析显示POM化学多样性较高,包含易降解的类蛋白(50％)和难降解的类腐殖质组分(50％),而类腐殖质占HA荧光...     

人工湿地空气微生物群落碳源代谢特征

采用BIOLOG-GN微平板分析自由表面流人工湿地空气微生物群落碳源代谢特征,阐明空气微生物群落代谢功能与环境因子相关性.结果表明,不同季节人工湿地空气微生物AWCD值、优势群落及Mc Intosh指数均存在差异,春季和夏季空气微生物碳源代谢强度明显高于秋季和冬季(P0.01);4个季节人工湿地空气微生物优势群落依次为羧酸类代谢群落、糖类代谢群落、聚合物类代谢群落和羧酸类代谢群落,夏季空气微生物对6类化合物的利用水平高于其他季节(P0.05).主成分分析显示,秋季和冬季空气微生物碳源代谢特征相似,但与春季和夏季差别较大,胺类是区分人工湿地夏季与春季、秋季和冬季的主要碳源类型,羧酸类是区分春季与秋季和冬季空气微生物代谢差异的主要碳源类型.不同季节人工湿地空气微生物群落结构主导影响因子存在差异.     

宁夏黄土丘陵区农田土壤细菌海拔分布特征

研究农田土壤微生物多样性、结构与功能的海拔分布特征及其影响因子,对保护农田生态系统生物多样性具有重要意义.利用高通量测序技术对宁夏黄土丘陵区农田土壤细菌多样性、群落结构和代谢功能沿海拔分布特征及其对土壤理化性质的响应进行分析.结果表明：(1)土壤细菌Alpha多样性指数与海拔呈显著负相关,沿海拔呈现先降低再略升高的变化趋势.(2)变形菌（Proteobacteria）、放线菌（Actinobacteria）和酸杆菌（Acidobacteria）等7个菌门为优势菌群,其中5个菌群在海拔间具有极显著性差异.(3)二级分类水平上包括膜运输、碳水化合物代谢和氨基酸代谢等36个细菌代谢功能,其中22个在不同海拔间具有显著性差异,12个具有极显著性差异.(4)Pearson相关分析表明,土壤含水量、容重、pH和碳氮比对细菌Alpha多样性影响最为显著,总有机碳、全氮和全磷等土壤养分对细菌Beta多样性具有显著影响.(5)Mantel分析表明,门水平细菌群落结构受土壤含水量、总有机碳和碳氮比影响,细菌代谢功能与土壤pH、总有机碳、全氮、全磷和碳氮比均有显著相关性.方差分解分析显示土壤含水量对群落结构解释度最高,pH对代谢功能解释度最高.由此可知,土壤含水量和pH是影响宁夏黄土丘陵区农田土壤细菌多样性、群落组成和代谢功能的主要土壤因子.     

汶川地震灾区不同气候区土壤微生物群落碳源代谢多样性

为探讨汶川地震灾区不同气候区土壤微生物群落功能代谢的变化,采用Biolog-ECO生态板技术,研究了亚热带湿润季风气候和半干旱干热河谷气候未受损区、受损治理区、受损未治理区土壤微生物碳源代谢的多样性变化特征.结果表明,平均颜色变化率(AWCD)在未受损区和受损治理区表现为亚热带湿润季风气候区半干旱干热河谷气候区,在受损未治理区表现为半干旱干热河谷气候区亚热带湿润季风气候区,不同气候区内受损未治理区AWCD值均处于最低水平;亚热带湿润季风气候区土壤微生物的碳源利用类型明显多于半干旱干热河谷气候区,在不同气候类型区内碳源利用种类均表现为受损治理区未受损区受损未治理区的趋势;不同气候区土壤微生物群落碳源代谢多样性特征差异显著,其中多样性指数和均匀度指数均表现为未受损区受损治理区受损未治理区,而受损治理区均具有最高的丰富度指数;土壤微生物群落的碳源代谢特征与土壤养分、地上植被生物量及植被覆盖度具有一定的相关性,表明地震及其次生灾害主要通过对地表植被和土壤环境的作用间接影响土壤微生物群落的碳源利用能力,在不同气候类型区与不同的受损治理情况下土壤微生物群落的碳源代谢特征具有显著差异.     

Listeria monocytogenes batch culture growth response to metabolic inhibitors

In certain environments nutrient and energy sources available to microorganisms can be limited. Foodborne pathogens must efficiently adapt in order to be successfully transmitted through the food chain to their hosts. For the intracellular foodborne pathogen Listeria monocytogenes, little is known regarding its response to nutrient/energy-limiting conditions. The alternative stress responsive sigma factor σ^B has been reported to contribute to survival under specific stresses. Therefore, the effects of several metabolic inhibitors on growth of L. monocytogenes wild-type and a ΔsigB mutant were examined. In the absence of inhibitors, both strains reached stationary phase after 18 h at 23°C and 10 h at 37°C. All of the metabolic inhibitors slowed growth of either strain, with few differences observed among the different inhibitors.     

A new approach to graphical and numerical analysis of links between plant chemotaxonomy and secondary metabolism from HPLC data smoothed by a simplex mixture design

Summary. HPLC analysis of secondary metabolites represents an efficient tool for the studying of plant chemical diversity under different aspects: chemotaxonomy, metabolomics, adaptative responses to ecological factors, etc. Statistical analyses of HPLC databases, e.g. correlation analysis between HPLC peaks, can reliably provide information on the similarity/dissimilarity degrees between the chemical compounds. The similarities, corresponding to positive correlations, can be interpreted in terms of analogies between chemical structures, synchronic metabolisms or co-evolution of two compounds under certain environment conditions, etc. . In terms of metabolism, positive correlations can translate precursor-product relationships between compounds; negative correlations can be indicative of competitive processes between two compounds for a common precursor(s), enzyme(s) or substrate(s). Furthermore, the correlation analysis under a metabolic aspect can help to understand the biochemical origins of an observed polymorphism in a plant species. With the aim of showing this, we present a new approach based on a simplex mixture design, Scheffé matrix, which provides a correlation network making it possible to graphically visualise and to numerically model the metabolic trends between HPLC peaks. The principle of the approach consisted in mixing individual HPLC profiles representative of different phenotypes, then from a complete mixture set, a series of average profiles were calculated to provide a new database with a small variability. Several iterations of the mixture design provided a smoothed final database from which the relationships between the secondary metabolites were graphically and numerically analysed. These relationships were scale-dependent, namely either deterministic or systematic: the first consisted of a monotonic global trend covering the whole variation field of each metabolites’ pair; the second consisted of repetitive monotonic variations which gradually attenuated or intensified along a global trend. This new metabolomic approach was illustrated from 404 individual plants of Astragalus caprinus (Leguminoseae), belonging to four chemical phenotypes (chemotypes) on the basis of flavonoids analysed in their leaves. After smoothing, the relationships between flavonoids were numerically fitted using linear or polynomial models; therefore the co-response coefficients were easily interpreted in terms of metabolic affinities or competitions between flavonoids which would be responsible of the observed chemical polymorphism (the four chemotypes). The statistical validation of the approach was carried out by comparing Pearson correlations to Spearman correlations calculated from the smoothed and the crude HPLC database, respectively. Moreover, the signs of the smoothed relationships were finely supported by analogies and differences between the chemical structures of flavonoids, leading to fluent interpretation in relation to the pathway architecture.     

玉米芯为碳源固定化硫酸盐还原菌污泥代谢特性

以聚乙烯醇为包埋载体,饱和硼酸为交联剂,制作了玉米芯为内聚缓释碳源的固定化硫酸盐还原菌污泥颗粒。通过厌氧批实验研究了在模拟酸性矿山废水(AMD)条件下玉米芯含量、初始SO42-和Mn2+负荷以及pH对固定化颗粒代谢特性的影响,初步分析了固定化颗粒处理AMD的机理及可行性。实验结果表明,玉米芯在微生物作用下快速水解并产生有机物累积后,固定化颗粒才能迅速还原SO42-,且玉米芯含量≤5%时硫酸盐还原率与玉米芯含量成正相关,玉米芯的水解会略微降低体系的pH;初始SO42-浓度通过改变体系中COD/SO42-和颗粒内外的浓度差影响固定化颗粒的代谢过程,而对玉米芯水解的影响不显著。初始pH为2~6和Mn2+浓度≤55 mg/L时对固定化颗粒活性抑制作用不明显,初始pH越低越利于玉米芯的水解和颗粒形成良好的孔隙结构;颗粒对Mn2+的去除机理是一种不依赖微生物活性的快速化学吸附作用,可用伪二级动力学模型描述吸附过程(R2=0.995)。     

废水中硝基酚类化合物生物降解的研究进展

硝基酚是一类重要且常用的化工原料,一些硝基酚毒性大且难以生物降解,被美国环保局列入“优先控制污染物名单”。在自然环境条件下,硝基酚的生物降解速率缓慢,导致硝基酚在环境中长期滞留和积累。分析了人工强化条件下废水中硝基酚的生物降解性能,主要从具有降解硝基酚能力的微生物、硝基酚的厌氧生物降解性、硝基酚的好氧生物降解性和硝基酚的共基质代谢降解方面进行了较全面的综述,讨论了该研究当前仍存在的一些问题和研究展望。     

太湖不同水域沉积物甲烷释放潜力及其途径分析

为明确太湖不同湖区CH4释放特征与释放潜力差异,采用水-气界面甲烷排放通量测定和室内厌氧培养,结合沉积物理化因子对太湖沉积物CH4释放特征及其释放潜力差异进行研究.结果 表明,不同湖区水-气界面CH4排放通量存在显著差异;不同湖区、不同深度沉积物中CH4释放潜力也存在明显差异,且CH4释放潜力与含水率和总有机碳呈正相关...