pH对间歇进水序批式生物反应(SBR)工艺活性污泥沉降性能和微生物结构的影响

本文主要研究了不同pH值对SBR工艺污泥膨胀和微生物结构的影响,试验进水pH值为5.0—10.0.实验结果表明,在试验初期,污泥容积指数(SVI)值无明显变化.但随着时间的增长,在pH值为5.0和6.0时,开始出现污泥膨胀.在不同pH下提取总细菌的DNA组进行PCR扩增,分析总细菌的Shannon多样性指数,对微生物群落的部分优势总细菌进行克隆测序和系统发育树分析.结果表明,在不同pH条件下微生物结构以及数量有所区别,在酸性条件下以丝状菌为主,易发生污泥膨胀;而在中性和偏碱性条件下以菌胶团为主,污泥活性较为稳定.     

小麦秸秆不同还田方式下土壤微生物碳代谢多样性特征

秸秆还田是影响稻田土壤固碳潜力的重要措施,研究秸秆不同还田方式下土壤微生物碳源代谢特征对提高农作物秸秆利用和增加土壤碳固定具有重要意义,为此采用自动微生物鉴定系统(Biolog-ECO)研究在短期耕作条件下小麦秸秆不同还田方式对稻田耕层土壤微生物群落结构和多样性的影响。以江苏省六合区黄棕壤为研究对象,对等氮量秸秆发酵床垫料化还田(SP)、秸秆炭化(补施化肥)还田(BR)、秸秆+猪粪发酵还田(OF)、传统施用化肥(CF)和不施肥(CK)对照处理土壤进行分层采样,采用Biolog-ECO方法揭示微生物群落结构的多样性,并采用主成分分析法(PCA)探讨土壤微生物群落结构的变化特征。结果表明,不同秸秆还田方式能显著影响土壤微生物碳代谢特征,OF处理土壤微生物碳代谢能力、微生物多样性各项指数及糖类、氨基酸、胺类和多聚物利用率明显高于其他处理;而SP处理土壤微生物的影响明显小于OF、BR处理;不同秸秆还田方式能显著影响土壤表层(0~5 cm)和耕作亚表层(5~10 cm)微生物碳利用,而对耕作底层(10~20 cm)的影响较小;不同秸秆还田方式影响土壤微生物多样性,与CF和BR处理相比,OF和SP处理增加了土壤微生物多样性。认为OF和BR处理可在短期内显著提高土壤微生物碳代谢多样性和对碳源的利用。     

基于高通量测序和传统分离研究雪茄外包皮表面细菌多样性及演替

细菌在烟叶发酵过程中起着重要作用,为探索烟叶的发酵机理,采用Illumina miseq高通量测序技术(Highthroughput sequencing,HTS)和传统微生物分离方法,对墨西哥不同发酵时期雪茄外包皮表面细菌群落结构、丰富度及演替进行研究.(1)HTS获得有效序列条数514 641条,包含65个OTUs,主要种属为棒状杆菌属(Corynebacterium)、葡萄球菌属(Staphylococcus)、不动杆菌属(Acinetobacter)、假单胞菌属(Pseudomonas)、芽孢杆菌属(Bacillus)等.HTS结果表明,墨西哥雪茄外包皮表面细菌群落组成丰富,细菌群落结构随发酵进程而变化,优势微生物由棒状杆菌属(44.64%)和假单胞菌属(40.88%)演替为后期的葡萄球菌属(72.78%).α多样性结果表明FJQY-1和FJQY-2样品的细菌群落具有较高的丰富度.β多样性分析发现FJQY-2、FJQY-3和FJQY-4三个样品细菌结构及丰度较为相似.(2)传统分离结果显示,不同发酵时期雪茄外包皮表面细菌主要为芽孢杆菌属(55.10%)和葡萄球菌属(22.45%),与HTS结果比较,单一传统分离方法不能全面反映不同时期雪茄外包皮表面细菌群落结构和演替.本研究表明,在不同发酵时期,雪茄外包皮表面细菌发生着群落演替;HTS测序在揭示微生物群落演替中发挥了重要作用;传统微生物分离鉴定方法不能全面反映微生物多样性及群落演替,但能获得发酵过程中的部分微生物用于后期功能研究.     

洛克沙胂暴露胁迫对土壤微生物群落结构特征的影响

采用磷脂脂肪酸(phospholipid fatty acid,PLFA)方法,分析了洛克沙胂残留对土壤微生物群落结构的影响特征。结果表明,在整个采样周期中,每克土壤总PLFA含量在洛克沙胂胁迫影响下出现明显降低,且存在一定的剂量依赖效应。经主成分分析,第1周,洛克沙胂低浓度组(w=15 mg·kg-1)土壤微生物群落结构和对照组差异不明显,第2、3、5、8周,各组土壤微生物群落结构多样性的类型差异显著,其中高浓度组(w=150 mg·kg-1)与对照组差异最大。结果表明,洛克沙胂可致土壤微生物群落结构多样性改变,暴露浓度越高其作用越强。同时,洛克沙胂对土壤微生物群落结构多样性的影响还表现出时间差异,在暴露胁迫的后期(第5、8周),洛克沙胂的影响逐步减弱,可能与洛克沙胂在土壤中发生化学结构改变和降解有关。     

基于MicroResp~(TM)不同施肥方式对土壤微生物群落的影响

土壤微生物群落代谢变化被认为是反映土壤质量和健康状况的敏感指标。通过5 a定位试验,采用MicroResp~(TM)方法分析不同施肥方式对农田土壤微生物群落功能多样性及其代谢结构的影响。结果表明,适量施用有机肥和沼液肥有利于提高土壤微生物代谢活性,并对土壤微生物群落代谢结构产生明显影响,但长期高量施用沼液肥不利于维持土壤微生物代谢活性和群落多样性。相关性分析结果表明,土壤pH值、全磷含量和Cu含量与土壤微生物代谢活性及其群落结构关系最密切,其中土壤Cu含量为主要影响因子。能明显提高土壤养分含量及导致土壤重金属Cu、Zn累积是有机肥较其他施肥方式对土壤微生物群落代谢功能产生显著影响的关键因素。     

新疆盐渍土3种植被类型土壤微生物碳源利用

研究了新疆天山以北三工河流域自然生境下梭梭(Haloxylon ammodendron)、琵琶柴(Reaumuriasoongonica)、隐子草(Cleistogenes chinensis)3种植被群落的土壤微生物碳源利用差异,分析了土壤理化性质与微生物总体活性、功能多样性的相关关系.采用BIOLOG生态板检测了各微生物群落对31种单一碳源的利用情况,结果表明,3种群落的微生物总体活性(AWCD)(F=41.877,P<0.001)、功能多样性(Shannon指数)(F=164.680,P<0.001)、丰富度(R值)(F=20.818,P=0.02)差异显著,其中梭梭植被下微生物群落的AWCD值、Shannon多样性指数、R值明显高于其他两种植被的微生物群落.土壤pH(相关系数=0.958,P<0.001)、土壤总碳相对含量(相关系数=0.718,P<0.05)与微生物总体活性(AWCD)呈显著相关,对微生物碳源利用有重要影响,而土壤可溶盐总量、含水率则与AWCD相关性不显著,微生物群落碳源利用功能多样性和丰富度与土壤理化性质均无显著相关关系.对于所研究的31种单一碳源,梭梭植被下微生物群落的利用情况也好于其他两种植被类型,对11种单一碳源利用情况较好,而琵琶柴、隐子草植被微生物群落分别则仅能对其中6种和5种碳源有较好的利用能力.     

放牧强度对环青海湖地区高寒草原土壤微生物群落碳代谢特征的影响

为了解青藏高原环青海湖地区放牧对土壤微生物群落碳代谢特征的影响,于2010年在青海省刚察县(N37°21′10″,E100°4′49″)高寒草原,设置围栏封育的禁牧对照组(CK)和牧草利用率分别为30%(G3)、40%(G4)、50%(G5)、60%(G6)和70%(G7)的5个放牧强度控制处理实验,于2014年7月采集土壤样品,运用Biolog-ECO微平板技术分析环湖地区土壤微生物群落碳源代谢特征的分布特征和变化规律.结果显示:(1)研究区域的土壤微生物主要利用碳源类型为氨基酸类和碳水化合物类;(2)放牧处理下土壤微生物群落主要碳源利用类型与利用率相似,与禁牧组显著不同;(3)禁牧和G4处理下土壤微生物的Shannon-Wiener指数、Simpson指数和Mc Intosh指数显著高于G3和G6、G7草原,与土壤有机碳和全氮含量变化规律相似.以上研究结果表明,放牧活动能显著影响环青海湖地区高寒草原土壤微生物群落代谢特征,禁牧和中度放牧(G4)有利于维持较高的土壤微生物群落多样性.     

城市中不同生境下鸟类群落特征研究

2004年1月至2004年12月,对内蒙古自治区呼和浩特市市区7种不同生态环境类型中的鸟类进行了调查研究。研究结果显示:商业区和交通占地中的鸟类群落最为相似,苗圃和公园中的鸟类群落较为相似。景观水平和干扰因素(样带至市中心的距离、噪音、建筑指标)对鸟类的分布、密度、多样性和丰富度具有不同程度的影响。分析表明,人为干扰影响鸟类多样性、群落结构和生态分布。     

长白山森林不同演替阶段土壤微生物群落结构

森林生态系统是陆地生态系统中最为重要的类型之一,土壤微生物是森林生态系统的主要调节者。随着森林演替的正向进行,地上植物类型和多样性的改变会造成土壤微生物群落结构组成的差别。为了深入探究长白山森林不同演替阶段的土壤生物学特性,为长白山地区森林资源的可持续发展提供理论数据,本研究选取长白山年龄为30年、70年、300年的森林样地,分析了长白山森林不同演替阶段土壤理化性质和微生物群落水平上的演变规律。结果表明,不同演替阶段土壤微生物群落结构存在差异,70年与30年和300年相比具有明显的变化,70年的土壤微生物总PLFAs含量以及多样性均显著高于300年,且土壤微生物群落结构受到土壤pH和土壤养分含量的显著影响。     

生物多样性的海拔分布格局研究及进展

生物多样性的海拔分布格局受制于气候、空间、环境等多种因子的影响,综合大量研究发现,无论是动植物还是微生物,环境因子对其影响与驱动的作用最明显。海拔梯度是决定分布格局的重要因素之一,因此探讨生物多样性在环境因子驱动下的海拔分布格局具有重要意义。文章分别探讨了植物、土壤动物和土壤微生物多样性沿海拔梯度的变化规律,揭示了温度、湿度及人为干扰等因素下植物多样性沿海拔梯度的5种分布格局及可能机制,土壤动物多样性沿海拔梯度的3种分布格局及可能机制,同时揭示土壤微生物在海拔分布格局虽然有物种模式,但是机制不是很明确;最后对植物、土壤动物、土壤微生物生物多样性耦合关系的认识作了阐述。并在此基础上,认为生物多样性的分布格局与尺度密切相关,因此开展不同尺度的生物多样性的研究以及它们对全球气候变化的响应是未来研究的重要方向;土壤动物群落的多样性的变化规律研究,应致力于其生理型、营养型、生态型的多样性的研究;在不同的研究尺度上,驱动微生物群落构建机制的差异导致了群落演变规律的变化,仍需要以地理学和生物学等相关学科理论为支撑,并与微生物群落构建理论相结合,对海拔分布格局下生物多样性的保护和生态系统稳定性研究提供科学依据。     

贵州喀斯特山区不同种植年限花椒根际土壤细菌群落结构特征研究

以贵州花江峡谷花椒(Zanthoxylum bungeamun)林为研究对象,采用16S rRNA高通量测序技术,分析种植5、10、20、30 a花椒根际土壤细菌群落结构和多样性特征,探讨不同种植年限花椒土壤理化因子对根际细菌群落分布的影响,为喀斯特石漠化地区花椒农业可持续发展提供有效的理论依据。结果表明,随着花椒种植年限的增加,土壤含水率、pH和有效磷逐渐升高,有机质、铵态氮和硝态氮含量先降低后升高(P<0.05)。根际土壤细菌Shannon、Simpson指数总体呈现上升趋势,OTUs、Chao1指数在10a较低。PCo A分析显示,不同种植年限花椒根际细菌群落组成差异显著,并且随着年限的增加,群落结构趋于相似;差异指示种分析表明,5—30a差异指示种分别为Firmicutes(厚壁菌门)、Cyanobacteria(蓝藻菌门)、Planctomycetes(浮霉菌门)、Entotheonellaeota(肠杆菌门)。RDA分析表明,有机质和含水率与细菌群落分布显著相关(P<0.05)。系统发育多样性分析表明,丰富类群多样性与环境因子存在较多的正相关,稀有类群比丰富类群有更强的发育信号。Bug Base预测分析发现:随着年限增加根际土壤好氧细菌增加,厌氧细菌下降,5、10 a氧化胁迫耐受菌低于20、30 a,致病菌在5、10 a高于20、30 a。综上,种植年限影响了花椒根际土壤细菌群落多样性,不同年限根际土壤肥力不同使得土壤细菌选择性生长,随着一定时间发育花椒抗病能力提高。     

Comparison on bacterial community of rhizosphere and bulk soil of poplar plantation based on pyrosequencing北大核心CSCD

By the 454 pyrosequencing technology, this research compared the bacterial communities in poplar plantation rhizosphere and bulk soil for an accurate understanding of bacterial community colonization in the two soil environments. The species annotation showed that rhizosphere soil contained 145 bacterial genera and bulk soil contained 141 bacterial genera, with 8 common genera shared by both at a relative abundance of more than 4%. The 8 genera in common were Acidobacterium GP1, Acidobacterium GP3, Acidobacterium GP6, Gemmatimonas, Bradyrhizobium, Burkholderia, Streptomyces and Acidobacterium GP4. The relative abundance of the same bacterial community was significantly different between rhizosphere and bulk soil environments. Alpha diversity analysis showed that the bacterial community diversity of rhizosphere soil was higher than that of bulk soil, but the difference was not significant. The results of bacterial communities sorting could reflect the variation of soil bacterial communities from rhizosphere to the bulk and the spatial variation among different sampling points, indicating a contribution of about 21.2% variance of bacterial communities by the effect of rhizosphere. Beta diversity analysis showed great difference between rhizosphere and bulk soil samples in bacterial community composition. There were 15 genera specific to rhizosphere soil and 11 to bulk soil. The abundance of 23 genera, mainly cellulose degrading bacteria and nitrogen-fixing bacteria, changed significantly. Selectivity of root to rhizosphere microorganisms is an important mechanism leading to significant differences in the rhizosphere microbial community composition and structure, which may significantly impact the carbon and nitrogen cycles of the root-soil interface.     

不同C/N值下亚硝酸盐氧化菌和异养菌混合体系的微生物多样性

采用PCR-RFLP技术研究了不同C/N比下亚硝酸盐氧化菌及异养菌混合体系的微牛物多样性,并探讨了微生物菌群结构与其功能(硝化件能)的关系.C/N=0时,混合体系主要由自养菌和寡营养菌(85.1%)组成,包括亚硝酸盐氧化菌(NOB)、拟杆菌门、α-变形菌纲、浮霉菌门和绿色非硫细菌中的一些菌株.C/N=0.44时,混合体系中的自养菌减少,异养菌(主要是γ-变形菌纲的成员)大量出现.C/N=8.82时,γ-变形菌纲的菌株尤其是反硝化菌Pseudomonas sp.占主导(93.8%),与此同时,随着C/N升高,该混合体系的硝化性能也由专一的亚硝酸盐氧化过程转变为同时硝化反硝化过程.微生物菌群结构的转变较好地解释了其硝化性能的改变.本研究揭示了微生物菌群结构与其功能的内在联系,同时表明PCR-RFLP技术与化学分析相结合是研究微生物菌群结构与功能的有力工具.图3表2参13     

Spatial characteristics analysis by PCR-DGGE for bacterial communities in surface sediments of Tangxi River,Hefei City北大核心CSCD

Microbes play an important role in material circulation and pollutant release in urban sediments, and its community structure can provide an important basis for evaluating the pollution load and ecosystem health of an urban river. In this study, bacterial communities in sediments from different locations of Tangxi River in Anhui Province were analyzed and compared, with an objective of evaluating the effects of aquatic environment on spatial characteristics of bacterial communities and the feasibility of using bacterial community composition as an indicator of urban river health. PCR-DGGE was applied to analyze the bacterial communities; fifteen major bands of 16S rDNA genes fragments from DGGE profiles of sediment samples were further eluted from gel, reamplified and sequenced. The sequences of these fragments were compared with the database in GenBank (NCBI). The collected samples were clustered based on UPGM Aanalysis. In addition, relationships between bacterial communities and environmental factors were analyzed by Monte Carlo test and redundancy analysis (RDA). The DGGE profiles indicated that upstream surface sediments had about 30 bands, but the differences in brightness were not significant. Although midstream surface sediments had only 18 bands on average, the brightness of some bands was relatively high, indicating that some dominant species of bacteria existed in these sediments. The amounts of bands in downstream sediments were between those of upstream and midstream, with some bands of high brightness. The NCBI comparison results showed that ten sequences shared 98-100% homology with known sequences, one with 97%, and the other four with uncultured bacteria. Shannon index (H) of bacterial diversity from upstream surface sediments was 3.31 on average, which was significantly (P < 0.05) higher than that of midstream surface sediments, and slightly higher than that of downstream surface sediments. UPGMA results showed both the distribution of bacteria communities and the diversity were strongly related with the sampling locations (Eigenvalue = 0.188, P = 0.134). Monte Carlo test and RDA analysis showed that the ion exchangeable form of nitrogen (IEF-N) was the main factor influencing the spatial characteristics of bacterial communities in the sediments. The aquatic plants had a significant effect on the richness of bacterial communities in the sediments, and the effectiveness of plant species was more notable than that of the vegetation coverage. The above results indicated that bacterial community structure and diversity in the surface sediments can well reflect the degree of urbanization development and effectiveness of ecological restoration in Tangxi River region.     

基于高通量测序的工业园区地下水和土壤细菌群落结构比较研究

为探究工业园区地下水和土壤细菌群落结构、多样性变化特征,采用高通量测序技术对地下水和土壤细菌16S r RNA基因高变区域进行序列测定。通过对Alpha多样性、物种组成、丰度和群落结构的分析,比较地下水和土壤细菌群落结构的异同。Alpha多样性的比较结果表明,土壤细菌群落多样性和丰富度明显高于地下水,地下水细菌群落多样性指数反映出地下水已受到周边污染源的影响。物种注释结果表明,地下水样品共检出48个细菌门,土壤样品共检出50个细菌门。变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)是地下水细菌群落的优势类群,共占93.54%,且该工业园区地下水细菌群落呈现出典型的淡水种群特征;土壤中优势细菌门为Proteobacteria、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、Firmicutes和芽单胞菌门(Gemmatimonadetes),共占85.21%。由于地下水和土壤两者的生态系统和理化环境的差异,致使Actinobacteria、Acidobacteria、绿弯菌门(Chloroflexi)、硝化螺旋菌门(Nitrospirae)、α-变形菌纲(Alphaproteobacteria)、δ-变形菌纲(Deltaproteobacteria)和Gemmatimonadetes占比在地下水和土壤细菌群落间差异显著,同时使地下水和土壤细菌群落各含有一些特有的优势细菌属(地下水2个,土壤4个)。基于高通量测序技术对工业园区样品的测序结果可以为地下水和土壤环境的生态评价提供方法依据。     

Co-fermentation of waste activated sludge with food waste for short-chain fatty acids production: effect of pH at ambient temperature

Effect of pH ranging from 4.0 to 11.0 on co-fermentation of waste activated sludge (WAS) with food waste for short-chain fatty acids (SCFAs) production at ambient temperature was investigated in this study. Experimental results showed that the addition of food waste significantly improved the performance of WAS fermentation system, which resulted in the increases of SCFAs production and substrate reduction. The SCFAs production at pH 6.0, 7.0, 8.0, and 9.0 and fermentation time of 4 d was respectively 5022.7, 6540.5, 8236.6, and 7911.7 mg COD·L^-1, whereas in the blank tests (no pH adjustment, pH 8.0 (blank test 1), no food waste addition, pH 8.0 (blank test 2), and no WAS addition (blank test 3)) it was only 1006.9, 971.1, and 1468.5 mg COD·L^-1, respectively. The composition of SCFAs at pH from 6.0 to 9.0 was also different from other conditions and propionic acid was the most prevalent SCFA, which was followed by acetic and n-butyric acids, while acetic acid was the top product under other conditions. At pH 8.0 a higher volatile suspended solids (VSS) reduction of 16.6% for the mixture of WAS and food waste than the sole WAS indicated a synergistic effect existing in fermentation system with WAS and food waste. The influence of pH on the variations of nutrient content was also studied during anaerobic fermentation of the mixture of WAS and food waste at different pH conditions. The release of NH4+-N increased with fermentation time at all pH values investigated except 4.0, 5.0 and in blank test one. The concentrations of soluble phosphorus at acidic pHs and in the blank test one were higher than those obtained at alkaline pHs. Ammonia and phosphorus need to be removed before the SCFAs-enriched fermentation liquid from WAS and food waste was used as the carbon source.     

优势菌种活细胞对天然水体中Pb^2＋和Cd^2＋的吸附

通过对天然水环境———伊通河中优势菌种活细胞吸附Pb2 、Cd2 的研究发现 :pH对Pb2 、Cd2 吸附的影响是不同的 ,对Pb2 的吸附量在 pH =5 .0～ 7.0时变化不大 ,对Cd2 的吸附量在 pH =6 .0～ 8.0时变化不大 ;温度对活细胞吸附Pb2 、Cd2 影响明显不同 ;活细胞对Pb2 、Cd2 的吸附量随着细菌密度的增加而增大 ,随着渗透压的增大而降低 .图 5表 1参 8     

Environmental controls on the landscape-scale biogeography of stream bacterial communities

We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with the relative distance between communities (Spearman's p = 0.66, P < 0.001) although there were other contributing factors, including the quality of the fine benthic organic matter and the amount of dissolved organic carbon and nitrogen in the stream water (P < 0.05 for each). There was no evidence of an effect of geographic distance on bacterial community composition, suggesting that dispersal limitation has little influence on the observed biogeographical patterns in streams across this landscape. Cloning and sequencing of small-subunit rRNA genes confirmed the DNA fingerprinting results and revealed strong shifts among bacterial groups along the pH gradient. With an increase in streamwater pH, the abundance of acidobacteria in the FBOM bacterial community decreased (from 71% to 38%), and the abundance of proteobacteria increased (from 11% to 47%). Together these results suggest that microorganisms, like "macro"-organisms, do exhibit biogeographical patterns at the landscape scale and that these patterns may be predictable based on biogeochemical factors.     

新疆黄萎病发病程度不同棉田土壤细菌群落结构差异分析

新疆棉区棉花黄萎病发生危害严重,提高该病的生态防控技术对实现棉花"化肥、农药"减施增效有重要意义。文章以阿克苏、石河子和库尔勒三地棉花黄萎病不同发生程度棉田土壤为研究对象,利用高通量测序技术对土壤细菌种群结构进行研究,并分析土壤理化性质与细菌多样性及种群结构的相关性,以期揭示棉田土壤的细菌群落结构差异及主要影响因子,为提高新疆棉花黄萎病生态防控技术提供依据。结果表明,在97%相似水平上,阿克苏、库尔勒重病棉田土壤细菌的OTU数量及ACE、Chao1、Shannon-Wiener指数均分别与其对照田土壤无显著差异,石河子重病田土壤细菌的ACE、Chao1指数均显著低于其对照田,而Shannon-Wiener指数显著高于对照田。聚类分析发现,阿克苏、石河子重病田均分别与对照田土壤的细菌群落组成差异显著,而库尔勒重病田与其对照田土壤细菌群落组成差异较小。在属水平上,阿克苏重病田土壤中有益菌群溶杆菌属(Lysobacter)和假单胞菌属(Pseudomonas)的丰度分别为3.67%和3.15%,均显著高于无病田对照(2.35%和0.18%),而芽胞杆菌属(Bacillus)和链霉菌属(Streptomyces)的丰度在阿克苏、石河子、库尔勒三地重病田与对照田之间均无显著差异。差异标记分析同样发现在阿克苏重病田中显著富集了假单胞菌目(Pseudomonadales),在石河子重病田中显著富集了放线菌门(Actinobacteria)。相关分析表明,棉田土壤细菌的OTU数量、Alpah多样性指数与土壤pH值、全钾含量呈正相关,与总盐含量、碳氮比呈负相关,与有机质、全氮、全磷含量及棉田发病程度无明显相关,土壤pH值、总盐含量是影响土壤细菌多样性的主要因子。     

Microbial interactions with the cyanobacterium Microcystis aeruginosa and their dependence on temperature

Associated heterotrophic bacteria alter the microenvironment of cyanobacteria and potentially influence cyanobacterial development. Therefore, we studied interactions of the unicellular freshwater cyanobacterium Microcystis aeruginosa with heterotrophic bacteria. The associated bacterial community was greatly driven by temperature as seen by DNA fingerprinting. However, the associated microbes also closely interacted with the cyanobacteria indicating changing ecological consequence of the associated bacterial community with temperature. Whereas concentration of dissolved organic carbon in cyanobacterial cultures changed in a temperature-dependent manner, its quality greatly varied under the same environmental conditions, but with different associated bacterial communities. Furthermore, temperature affected quantity and quality of cell-bound microcystins, whereby interactions between M. aeruginosa and their associated community often masked this temperature effect. Both macro- and microenvironment of active cyanobacterial strains were characterized by high pH and oxygen values creating a unique habitat that potentially affects microbial diversity and function. For example, archaea including ‘anaerobic’ methanogens contributed to the associated microbial community. This implies so far uncharacterized interactions between Microcystis aeruginosa and its associated prokaryotic community, which has unknown ecological consequences in a climatically changing world.