环境水体微囊藻毒素微生物降解技术研究进展

湖库水体富营养化及其产生的藻毒素污染已对生态环境和人类健康构成极大威胁,而目前常规水污染控制技术存在一定的局限性,因此水环境中藻毒素处理新工艺亟待研发.鉴于环境水体中的微囊藻毒素可被微生物降解为无毒或低毒的中间产物,本文综述了微囊藻毒素的降解菌株、生物降解过程影响因素与机理、降解产物及其结构特性等,总结了目前微囊藻毒素降解菌株在水环境修复中的应用,并对今后微生物降解微囊藻毒素的研究方向进行了展望,以期为解决我国日益严峻的湖库水体藻毒素污染和饮用水安全问题提供技术思路.     

黄曲霉毒素B1生物脱毒的研究进展

黄曲霉毒素是一组由黄曲霉、寄生曲霉等多种真茵产生的次级代谢产物,具有强烈的毒性,可以引起动物肝脏肿大、病变甚至癌变,对人和家畜的健康产生极大的威胁。本文简介了黄曲霉毒素B_1的分子结构、理化性质、污染现状,综述了黄曲霉毒素B_1生物脱毒方面及其应用的研究进展,重点讲述通过微生物降解黄曲霉毒素B_1的研究近况。     

赤潮藻毒素危害及其检测方法研究进展

近年来,世界各地包括我国部分沿海地区赤潮发生过度频繁,许多赤潮藻毒素不但使其他海洋生物中毒,对人类健康也有潜在的危害,因此对赤潮藻毒素的研究已经成为海洋环境科学研究的重要内容。我们介绍了赤潮藻毒素的危害,并详细综述了赤潮藻毒素检测技术研究进展。     

海洋微藻溶血毒素研究进展

对海洋微藻溶血毒素的类型、理化性质、生物合成和毒性作用进行了综述,分析了存在的问题和应用前景的展望。     

赤潮藻毒素生物合成研究进展

合成毒素是赤潮藻类的一个常见特征,已知能够产生毒素的微藻有70多种。作为次级代谢产物,藻毒素的产生可能是一种压制或清除其它藻类竞争者的一种反应,在群落演替、种间竞争中发挥重要作用。目前,人们对藻毒素生物合成机理依然知之甚少,相关基因的研究仍无明显突破。利用环境因子诱导毒素生成变化进而分离差异表达基因或者比较不同产毒藻株间基因表达的差异,从中克隆藻毒素生物合成基因似乎是一种极具潜力的研究方向。     

铁对藻类生长及藻毒素合成影响研究进展

铁作为藻类生长发育所必需的矿质营养元素之一,在藻类光合作用、呼吸作用、固氮作用、蛋白质与核酸合成等生理代谢过程中发挥着极为重要的作用.鉴于水体中不同形态铁可被藻类吸收利用,本文综述了铁在水体中的存在形态和循环途径、藻类吸收铁的机理、铁对藻类生长及藻毒素合成的影响,总结了有关微囊藻毒素合成基因及其在铁限制条件下的表达,并对今后铁蛋白基因调控藻类富营养化的研究方向进行了展望,以期为水体富营养化修复技术提供参考.     

生物法处理木质素的研究进展

对生物法处理木质素进行了简要概述,包括微生物降解、生物法酸析提取木质素以及生物法纯化木质素的效果及其研究进展.生物法处理木质素对资源的合理利用、经济的发展以及环境保护具有重要的意义.     

节球藻毒素研究进展

节球藻毒素(Nodularin)是由泡沫节球藻(Nodularia spumigena)产生的一种环状五肽肝毒素。节球藻毒素对陆生动物和人体均具有毒性和致癌作用,还会影响水生生态系统的结构和功能,对许多陆生植物、水生动物的生长繁殖具有一定的威胁,受到了社会的广泛关注。综述了节球藻毒素的分子结构、检测方法和产生途径,深入讨论了节球藻毒素的环境归趋和毒性效应的研究进展,并对其重要的研究领域提出进一步的展望。     

应用环境微生物治理淡水湖泊微囊藻毒素污染的研究进展

近年来,随着水体富营养化程度的加剧,蓝藻水华现象时有发生,蓝藻及其释放的藻毒素对生态环境和人类健康构成严重威胁。在各种藻毒素中,以微囊藻毒素(Microcystins,MCs)毒性最强,对人类危害也最大,微囊藻毒素的化学性质相对稳定且难以通过常规水处理方法消除,因此如何有效去除环境中的MCs是国内外普遍关注的难题。研究发现自然界中的微生物能够有效降解和消除MCs污染,由此产生的环保技术极具应用价值。本文主要概述了微囊藻毒素的产生机理、化学结构以及毒性危害,总结了微囊藻毒素的自然分解过程以及微生物群落对微囊藻毒素的响应机制,重点分析了微生物群落在微囊藻毒素污染控制技术中的潜在应用,并对应用微生物技术治理微囊藻毒素污染的技术瓶颈提出了建议,以期加速微囊藻毒素微生物降解技术的完善和应用。     

低温环境中T-2毒素降解菌的分离鉴定及特性研究

离筛选低温环境中T-2毒素的降解菌并探明其生化特性,探究T-2毒素降解微生物生化特性异同点,为T-2毒素降解微生物的检验提供生化判断参考。针对暴露于－20 ℃低温环境中的低浓度T-2毒素标准品,采用LC-MS/MS定量分析T-2毒素残留量,利用营养琼脂培养基（NA）和马铃薯葡萄糖琼脂培养基（PDA）共分离出5株降解菌,16S rDNA结合生化鉴定结果为死谷芽胞杆菌（Bacillus vallismortis）、蜡状芽胞杆菌（Bacillus cereus）、阴沟肠杆菌（Enterobacter cloacae）、弯曲假单胞菌（Pseudomonas geniculata）和尼泊尔葡萄球菌（Staphylococcus nepalensis）。这些分离株在－20 ℃条件下对低浓度T-2毒素均有不同程度的降解能力,其中蜡状芽胞杆菌（Bacillus cereus）降解能力最强,降解率为91%。它们的理化特性具有很多相似性,主要表现在5株菌均不能利用D 塔格糖(dTAG）,对ELLMAN都表现出阴性;Bacillus vallismortis Bp1234-7、Pseudomonas geniculata Bp24-4、〖WTBX〗Staphylococcus nepalensis Bp124-5和Enterobacter cloacae Bp123-7都能分解D-葡萄糖,而Bacillus cereus Bp1234-8不能。     

Enzymatic Evaluation of Oxidation Pond Performance

A one year study on a waste oxidation pond was undertaken to observe the behaviour of four enzymes, viz catalase, phosphatase, protease and amylase with respect to other ecological factors. The increase in solar radiation from March to May enhanced phytoplankton growth resulting in increased pH and DO and considerable reduction in nutrients and BOD. Variations in the activity of enzymes seemed to be directly related to bacterial number. The activity of catalase and phosphatase seemed to be related to the microbial density and nutrient status of the pond. The activity of protease and amylase could be used as a measure of degradation of organic matter.     

Impact of Anthropogenic Organic Matter on the Distribution Patterns of Sediment Microbial Community from the Yangtze River,China

Abstract

How microbes respond to substantial and increasing anthropogenic disturbance remains an open question in river systems. We tested the hypothesis that the source and distribution of anthropogenic organic matter (OM) were significant factors affecting the spatial variation of the microbial community composition of the Yangtze River sediments. Bulk geochemical proxies and lignin phenols suggested a general decrease of terrestrial C3 plants or soil OM input from the middle to the lower reaches. Fecal sterols inferred higher sewage contamination levels in the middle reaches. Polycyclic aromatic hydrocarbons (PAHs) distribution indicated a dominant biomass and coal combustion signal in the middle reaches, whereas a mixed source including petroleum combustion in the lower reaches. Phylogenetic analysis revealed a large portion of Methanobacteria and Verrucomicrobia enriched in the middle reaches, whereas OM-degrading bacteria, including Flavobacteria, Acidobacteria, and Alphaproteobacteria were dominant in the lower reaches. Quantitative PCR analyses and multivariate analysis further demonstrated that sources and distribution of OM had combined effects in shaping alpha and beta-diversity of sediment microbial communities. Sewage discharge and incomplete OM combustion, respectively, were associated with Methylococcaceae, Chloroflexi, and Bacteroidetes groups. This study provides a foundation for further understanding of the river sediment microbial composition, considering the continued increase of anthropogenic influences.     

节球藻毒素对草鱼淋巴细胞凋亡毒性效应及机理

节球藻毒素是水华水体中发现的一种新型蓝藻毒素,鱼类很容易受到节球藻毒素的影响.本研究发现节球藻毒素能够体外诱导草鱼淋巴细胞发生凋亡.电镜观察从形态学上发现节球藻毒素诱导的草鱼淋巴细胞呈现明显的细胞质浓缩、染色质凝集以及边缘化等典型细胞凋亡特征.梯队状DNA进一步证实凋亡的发生.1、10和 100 μg·L^-1的节球藻毒素体外诱导草鱼淋巴细胞12 h后,凋亡率分别达到19.4%、31.6%和71.6%,具有明显的剂量效应特征.节球藻毒素诱导的草鱼淋巴细胞凋亡与胞内活性氧物质增加、线粒体膜电位下降、胞钙含量上升、Bcl₂基因下调和Bax基因上调有关;此外,Caspase-3和Caspase-9两种酶参与该凋亡过程.表明节球藻毒素能够通过线粒体通路诱导鱼体淋巴细胞发生凋亡.
     

高寒草甸不同植被土壤微生物数量及微生物生物量的特征

用稀释平板法和氯仿熏蒸法研究了藏嵩草草甸、小嵩草草甸、矮嵩草草甸、禾草草甸、杂类草草甸及金露梅灌丛土壤的微生物数量、生物量及有机质的变化特征.结果表明:0～40 cm土层细菌和放线菌数量、微生物生物量碳和土壤有机质含量均以藏嵩草草甸最高,其微生物生物量及土壤有机质显著高于其它5种植被;真菌数量以金露梅灌丛最高;由表层到深层,随着土壤深度的增加以上各项指标均呈下降趋势.通径分析表明:土壤各生物环境因子之间存在着不同程度的相关性;土壤微生物数量、生物量及土壤有机质含量均与土壤水分含量存在显著的相关关系,说明土壤水分是调节高寒草甸生态系统土壤微生物代谢及物质转化的关键因子.     

Degradation of surface-water dissolved organic matter: influences of DOM chemical characteristics and microbial populations

The degree to which biodegradation of dissolved organic matter (DOM) depends on microbial community structure and source remains unknown. In this study, we concentrated the microbial biomass from two streams in northern Michigan and a dystrophic bog lake in northern Wisconsin with varying initial DOM concentration (6.7–78.8 mg C l^–1) and DOM chemical characteristics (e.g. DOM average molecular weights from 808–1887 Da). Each of the three microbial inocula was added to each of the three DOM sources at in situ population levels for a total of nine treatments. Changes in DOM concentration and bacterial productivity, along with chemical characteristics, were examined over 308 h. The [³H]-leucine incorporation method was used to measure microbial production. In two of three sampling sites, bacterial communities were most productive when metabolizing DOM in their native waters. A variable peak in productivity was seen between 16–48 h after inoculation, followed by a drop in productivity in most treatments, with periods of DOM production most likely due to microbial turnover. These data suggest that microbial communities are better able to degrade the DOM of their native habitats, suggesting that biodegradation of DOM is influenced by source-specific microbial species and DOM chemical characteristics.     

萘对川西亚高山森林土壤呼吸、可溶性有机质和微生物生物量的影响

通过原位控制试验,研究了萘对川西亚高山森林土壤动物抑制效率、土壤呼吸、可溶性有机质和微生物生物量的影响.结果表明:萘施用显著抑制了大型和中小型土壤节肢动物的个体密度和类群数量,个体密度分别下降76.3%~78.5%和83.3%~84.8%,类群数量分别降低48.3%~56.1%和45.8%~58.3%.萘处理与对照的土壤呼吸速率季节动态呈单峰曲线,分别以2月和8月为最低值和最高值,而且未受萘施用的显著影响.与对照相比,萘处理显著降低了8月和10月土壤可溶性碳和可溶性氮含量,以及4月和8月微生物生物量碳,增加了4月的微生物生物量碳氮比.萘处理和采样时间的交互作用显著影响了微生物生物量碳和微生物生物量氮,但对土壤动物个体密度和类群数量以及可溶性碳含量影响不显著.总体上,萘作为抑制剂,在川西亚高山森林土壤能够有效地抑制土壤动物节肢动物,且并未显著影响土壤呼吸,但对土壤碳氮组分造成了不同程度的影响.     

Significance of bacterial ectoenzymes in aquatic environments

The report presents studies on temporal and spatial variations of kinetics (Vmax and Km) of bacterial ectoenzyme activity (-glucosidase - Glc, leucine aminopeptidase - Leu-amp) in the naturally eutrophic Plusee. Glc and Leu-amp activity were positively correlated with the flux of polymeric materials (polysaccharides, proteins) in the lake. Glc activity was low when algal populations grew actively, but during the algal bloom breakdown Glc activity increased rapidly. Leu-amp displayed the highest rates of activity in the epilimnion and was tightly coupled to bacterial production. The synthesis of studied ectoenzymes was under control of a repression/derepression mechanism. The significance of ectoenzymes for the transformation and bacterial utilization of organic matter, and their role in the microbial loop in aquatic environments is discussed.     

石灰土演替过程中颗粒态有机质和矿物结合态有机质的微生物群落特征

碳酸盐岩经风化作用并在地形、植被、气候、时间及生物等因素的影响下逐渐演替出黑色石灰土、棕色石灰土、黄色石灰土和红色石灰土。【目的】研究不同演替阶段石灰土颗粒态有机质(particulate organic matter, POM)和矿物结合态有机质(mineral-associated organic matter, MAOM)的微生物群落特征,为岩溶土壤有机质稳定机制研究提供理论依据。【方法】以广西弄岗国家级自然保护区的黑色石灰土、棕色石灰土、黄色石灰土和红色石灰土为研究对象,运用湿筛法将土壤有机质(soil organic matter, SOM)分为POM和MAOM,分析其理化性质以及微生物群落特征。【结果】石灰土演替过程中POM和MAOM的有机碳、总氮、交换性钙含量均呈下降趋势,且MAOM的C/N均大于POM,POM的C/P均大于MAOM。细菌α多样性在黑色石灰土POM和MAOM中最高,且四类石灰土MAOM的真菌多样性比POM要高。Acidobacteria、Proteobacteria、Ascomycota均为石灰土演替过程中POM和MAOM的优势菌门。总磷是影响石灰土演替过...     

Soil microbial response in tallgrass prairie to elevated CO2

Terrestrial responses to increasing atmospheric CO₂ are important to the global carbon budget. Increased plant production under elevated CO₂ is expected to increase soil C which may induce N limitations. The objectives of this study were to determine the effects of increased CO₂ on 1) the amount of carbon and nitrogen stored in soil organic matter and microbial biomass and 2) soil microbial activity. A tallgrass prairie ecosystem was exposed to ambient and twice-ambient CO₂ concentrations in open-top chambers in the field from 1989 to 1992 and compared to unchambered ambient CO₂ during the entire growing season. During 1990 and 1991, N fertilizer was included as a treatment. The soil microbial response to CO₂ was measured during 1991 and 1992. Soil organic C and N were not significantly affected by enriched atmospheric CO₂. The response of microbial biomass to CO₂ enrichment was dependent upon soil water conditions. In 1991, a dry year, CO₂ enrichment significantly increased microbial biomass C and N. In 1992, a wet year, microbial biomass C and N were unaffected by the CO₂ treatments. Added N increased microbial C and N under CO₂ enrichment. Microbial activity was consistently greater under CO₂ enrichment because of better soil water conditions. Added N stimulated microbial activity under CO₂ enrichment. Increased microbial N with CO₂ enrichment may indicate plant production could be limited by N availability. The soil system also could compensate for the limited N by increasing the labile pool to support increased plant production with elevated atmospheric CO₂. Longer-term studies are needed to determine how tallgrass prairie will respond to increased C input.