模拟酸雨对毛竹阔叶林过渡带土壤真菌结构及其多样性的影响

为探究酸雨对毛竹扩张形成的竹阔混交林土壤真菌群落的影响程度,于2017～2018年在浙江省杭州临安天目山国家级自然保护区开展酸雨模拟实验,选取T1(pH=4.0)和T2(pH=2.5)两个模拟酸雨梯度,并以CK(pH=5.5)对照,利用Illumina MiSeq高通量测序技术,分析不同强度酸雨胁迫下,土壤真菌群落多样性变化及影响因素.结果表明与对照相比,T1处理显著提高了真菌群落的OTU数量、Chao1指数和Ace指数(P0.05).竹阔混交林土壤主要由13个门类群的菌群组成,优势菌群包括子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、被孢霉门(Mortierellomycota)和毛霉门(Mucoromycota).主坐标(PCoA)分析和相似性检验结果表明模拟酸雨改变了土壤真菌结构.Bifiguratu属、Geminibasidium属、Purpureocillium属和Oidiodendron属相对丰度变化显著,可作为酸雨胁迫下土壤真菌群落结构变化的指示种.冗余分析(RDA)和相关性分析表明,土壤pH和全氮对土壤真菌群落结构影响显著(P0.05).综上所述,酸雨提高了真菌群落多样性指数,改变土壤真菌群落结构.该研究结果有助于了解森林生态系统中的真菌群落,以及土壤真菌作为影响因子在预测环境变异中的作用.     

Effect of vegetation of transgenic Bt rice lines and their straw amendment on soil enzymes, respiration, functional diversity and community structure of soil microorganisms under field conditions

With the development of transgenic crops, there is an increasing concern about the possible adverse effects of their vegetation and residues on soil environmental quality. This study was carried out to evaluate the possible effects of the vegetation of transgenic Bt rice lines Huachi B6 (HC) and TT51 (TT) followed by the return of their straw to the soil on soil enzymes (catalase, urease, neutral phosphatase and invertase), anaerobic respiration activity, microbial utilization of carbon substrates and community structure, under field conditions. The results indicated that the vegetation of the two transgenic rice lines (HC and TT) and return of their straw had few adverse effects on soil enzymes and anaerobic respiration activity compared to their parent and distant parent, although some transient differences were observed. The vegetation and subsequent straw amendment of Bt rice HC and TT did not appear to have a harmful effect on the richness, evenness and community structure of soil microorganisms. No different pattern of impact due to plant species was found between HC and TT. It could be concluded that the vegetation of transgenic Bt rice lines and the return of their straw as organic fertilizer may not alter soil microbe-mediated functions.     

Simultaneous Fe(III) reduction and ammonia oxidation process in Anammox sludge

In recent years, there have been a number of reports on the phenomenon in which ferric iron (Fe(III)) is reduced to ferrous iron [Fe(II)] in anaerobic environments, accompanied by simultaneous oxidation of ammonia to NO₂^-, NO₃^-, or N₂. However, studies on the relevant reaction characteristics and mechanisms are rare. Recently, in research on the effect of Fe(III) on the activity of Anammox sludge, excess ammonia oxidization has also been found. Hence, in the present study, Fe(III) was used to serve as the electron acceptor instead of NO₂^-, and the feasibility and characteristics of Anammox coupled to Fe(III) reduction (termed Feammox) were investigated. After 160days of cultivation, the conversion rate of ammonia in the reactor was above 80%, accompanied by the production of a large amount of NO₃^- and a small amount of NO₂^-. The total nitrogen removal rate was up to 71.8%. Furthermore, quantities of Fe(II) were detected in the sludge fluorescence in situ hybridization (FISH) and denaturated gradient gel electrophoresis (DGGE) analyses further revealed that in the sludge, some Anammox bacteria were retained, and some microbes were enriched during the acclimatization process. We thus deduced that in Anammox sludge, Fe(III) reduction takes place together with ammonia oxidation to NO₂^- and NO₃^- along with the Anammox process.     

锰砂人工湿地对污染物的强化去除

锰砂由于其具有强氧化和吸附作用已被广泛应用于净水领域中,而在人工湿地中以锰砂为填料的相关研究较少.根据前期研究推测,在人工湿地的基质中加入锰砂,其能通过氧化吸附强化去除水中的污染物,而还原生成的Mn （Ⅱ）又能被土壤及根系锰氧化微生物氧化为Mn （Ⅲ/Ⅳ）,进而防止Mn （Ⅱ）在水中的释放.为验证该推测,本研究探讨了加入锰砂的芦苇人工湿地对污染物的强化去除能力及微生物学机制.通过比较加入和未加入锰砂（对照组）的人工湿地的运行效果,发现锰砂人工湿地对溶解性有机碳（DOC）、TN和冬季时期NH₄⁺-N的去除具有显著的提升作用.16S rRNA测序结果表明,锰砂基质能显著提升冬季芦苇根系微生物的丰富度和多样性,但对人工湿地整体的群落结构影响较小,这可能与锰砂湿地强化污染物去除能力有关.本研究为人工湿地工艺优化提供了一种新思路.     

高通量测序技术研究典型湖泊岸边陆向深层土壤中厌氧氨氧化细菌的群落结构

为研究具有富营养化特征的白洋淀湖泊岸边陆向深层土壤中厌氧氨氧化细菌的群落结构组成,针对厌氧氨氧化的功能基因hzs B(联氨合成酶关键基因)进行高通量测序.结果显示,白洋淀湖泊岸边陆向深层土壤共8个样品处理后共得到77082条序列,在相似度90%下聚类得到40个OTUs.多样性分析(OTUs水平)表明,在白洋淀湖泊岸边近湖岸交界处,上层土壤中厌氧氨氧化细菌的群落多样性要高于下层,而在远湖岸交界处则相反,下层土壤中厌氧氨氧化细菌的群落多样性要高于上层土壤.PCo A分析(OTUs水平)表明,近湖岸交界处采样点各不同深度土壤层之间的厌氧氨氧化细菌的群落结构更相似,而远湖岸界面处采样点各不同深度之间的厌氧氨氧化细菌的群落结构差异较大.群落结构分析表明,在白洋淀湖泊岸边陆向深层土壤中,序列隶属于Candidatus‘Brocadia anammoxidans’(34.07%)、Candidatus‘Brocadia fulgida’(24.66%)、Candidatus‘Jettenia sp.’(3.00%)、Candidatus‘Kuenenia sp.’(0.22%)、Candidatus‘Scalindua sp.’(0.08%)及与Genbank中已探明的厌氧氨氧化细菌亲缘关系较远的Anammox-like cluster(37.98%).相关性分析(p0.10)表明,在白洋淀湖泊岸边陆向深层土壤中,厌氧氨氧化细菌α-多样性指数中丰富度Chao指数与含水率(MC)呈负相关,多样性Shannon指数与氨氮(NH+4)呈负相关,优势度Simpson指数与NH+4呈正相关;但厌氧氨氧化细菌群落组成中Candidatus‘Brocadia anammoxidans’的富集与总碳(TC)及总硫(TS)含量呈正相关.综上,本文针对厌氧氨氧化功能基因hzs B扩增进行高通量测序,一定程度上揭示了具有富营养化特征的白洋淀湖泊岸边陆向深层土壤中厌氧氨氧化细菌的多样性、群落组成及其与土壤环境因子的关系.     

Effects of vegetation type on soil microbial community structure and catabolic diversity assessed by polyphasic methods in North China

Soil microbes play a major role in ecological processes and are closely associated with the aboveground plant community.In order to understand the effects of vegetation type on the characteristics of soil microbial communities,the soil microbial communities were assessed by plate counts,phospholipid fatty acid (PLFA) and Biolog microplate techniques in five plant communities,i.e.,soybean field (SF),artificial turf (AT),artificial shrub (AS),natural shrub (NS),and maize field (MF) in Jinan,Shandong Province,North China.The results showed that plant diversity had little discernible effect on microbial biomass but a positive impact on the evenness of utilized substrates in Biolog microplate.Legumes could significantly enhance the number of cultural microorganisms,microbial biomass,and community catabolic diversity.Except for SF dominated by legumes,the biomass of fungi and the catabolic diversity of microbial community were higher in less disturbed soil beneath NS than in frequently disturbed soils beneath the other vegetation types.These results confirmed that high number of plant species,legumes,and natural vegetation types tend to support soil microbial communities with higher function.The present study also found a significant correlation between the number of cultured bacteria and catabolic diversity of the bacterial community.Different research methods led to varied results in this study.The combination of several approaches is recommended for accurately describing the characteristics of microbial communities in many respects.     

重金属铜、锌、镉、铅复合污染对土壤环境微生物群落的影响

以铜锌冶炼厂附近的水稻土为例 ,研究了重金属复合污染对土壤微生物群落的影响 .结果表明 ,有效铜、锌、镉、铅与微生物生物量碳、微生物生物量氮、微生物商、微生物生物量氮 全氮均呈显著负相关 .重金属污染均能降低细菌、真菌和放线菌的数量 .用BIOLOG生态盘研究了重金属污染对微生物群落结构的影响 ,发现重金属污染明显影响了微生物群落结构 ,反映在典型变量 1(CV1)与重金属元素含量呈极显著正相关 ,因此认为典型变量 1是反映重金属污染程度的有效指标 .经逐步回归分析发现 ,有效铜是影响典型变量 1最主要的因素 .     

白洋淀养殖区春季沉积物垂向微生物群落特征及驱动因素

结合16S rRNA高通量测序技术,对春季白洋淀养殖区（后塘和西李庄）沉积物垂向细菌群落演变特征及影响因素进行解析.结果表明：春季白洋淀沉积物环境因子（硝态氮、铵态氮、溶解性总磷、紫外光谱指数、三维荧光光谱指数和荧光组分强度）均呈现显著差异（p<0.05）,后塘采样点的硝态氮和铵态氮含量明显高于西李庄采样点;高通量测序得到23527个OTU,共分为11个主要门类,其中,变形菌门占比最大,达到15.33%~50.59%;α-多样性显示除辛普森指数和覆盖率外,ACE指数、Chao指数及香农指数呈现显著差异（p<0.05）,并且在后塘采样点高于西李庄;主坐标分析表明,后塘与西李庄采样点沉积物细菌群落存在显著差异,与Adonis分析的结果相一致（p<0.01）;RDA分析发现,硝态氮和铵态氮是驱动沉积物细菌群落结构演变的主要环境因素;物种间网络分析显示,春季后塘和西李庄都为8个主要的模块,西李庄正向相关的边所占比例高达84.79%,明显高于后塘的62.82%;西李庄有244个关键物种OTU,也高于后塘的59个关键物种OTU;相关性分析得出两个采样点在主要属和模块上都存在差异,硝态氮、铵态氮、腐殖化指数（HIX）及生物源指数（BIX）是其主要环境因子.综上,通过对该时期养殖区沉积物垂向细菌群落演变特征及影响因素进行研究,可为白洋淀养殖区的污染控制提供技术支持.     

基于流体分离污泥的异质性:微生物活性和群落结构

生物流化床处理系统中的剩余污泥如果能够被识别为老化的污泥和高活性的污泥,并通过某一种物理方法加以原位分离,则有可能提高生物处理的效率.本文以构造流体力场实现基于比重分布不同污泥组分的分离,得到聚结型污泥与离散型污泥,考察了两种污泥在胞外聚合物、微生物活性和微生物群落结构方面的差异,并与降解活性相关联,以证明异质性的存在.研究发现:活性污泥这种异质性的存在归因于离散型污泥中的胞外聚合物含量高,亲水性更强,比重更小;聚结型污泥在基质利用效率、比耗氧速率方面优于离散型污泥;在废水生物处理系统的污泥中,聚结型污泥较离散型污泥具有微生物群落结构分布上的优势,种群丰度更高.研究结果证明了聚结型污泥和离散型污泥内部菌胶团存在着功能上的差异,前者是应该被保留的活性组分,后者应该作为剩余污泥加以分离排出.     

基于NMDS和RDA方法分析贵州百花水库后生浮游动物群落结构动态

为探究百花水库后生浮游动物群落结构特征,于2014年8月-2015年4月采用NMDS（非度量多维尺度分析）和RDA（冗余分析）方法,分析了水库后生浮游动物组成、季节演替规律及其群落与环境因子的相关性.结果表明:①百花水库共监测到后生浮游动物41种.其中,轮虫类28种,枝角类8种,桡足类5种;优势种为曲腿龟甲轮虫（Keratella valga）、螺形龟甲轮虫（Keratella cochlearis）、角突臂尾轮虫（Brachionus angularis）、圆筒异尾轮虫（Trichocerca cylindrica）、红多肢轮虫（Polyarthra remata）、中剑水蚤（Mesocyclops）、长额象鼻溞（Bosmina longirostris）.②NMDS结果显示,后生浮游动物群落结构呈明显的季节性差异.将群落结构演替划分为3个类群,即Ⅰ组（夏季、秋季组,以螺形龟甲轮虫、圆筒异尾轮虫等为优势种,共计8种）、Ⅱ组（冬季组,以螺形龟甲轮虫、长额象鼻溞等为优势种,共计7种）、Ⅲ组（春季组,以沟痕泡轮虫和红多肢轮虫等为优势种,共计7种）.③RDA结果表明,百花水库后生浮游动物群落结构变化受水环境因子影响较为明显,整体上WT（水温）、pH、ρ（TP）和ρ（NO₃--N）是影响百花水库后生浮游动物群落结构变化的主要因素.研究显示,根据后生浮游动物优势种及现存量（丰度、生物量）大小,可以判定百花水库后生浮游动物群落结构具有明显的季节性差异.