Anaerobic digestion is a promising process that is widely used to degrade a variety of types of waste biomass and recover energy in the form of methane. However, the low conversion efficiency and unstable performance of anaerobic digestion (AD) owing to volatile fatty acid (VFA) accumulation are common problems for the stable operation of the biogas reactor. Also, the disturbance and inhibition of AD frequently occur, which could be ascribed to the temperature and pH, the lack of nutrients, or the presence of ammonia. Hydrochar is the product of the hydrothermal liquefaction of biomass with pressurized and heated water. It has abundant redox-active properties and adsorption ability that might enable it to participate in electron transfer and accelerate VFA degradation, alleviate VFA accumulation, and inhibit ammonia. The possibility of hydrochar as an exogenous material to facilitate direct interspecies electron transfer is worth exploring. Hydrochar, together with other carbon-based materials, has received much attention as exogenous materials to promote AD, although theories and findings regarding hydrochar on AD have been insufficient or not clearly clarified. Therefore, we summarize findings on hydrochar from our research group, which revealed the effect of hydrochar on AD and especially on methane production, microbial mechanisms revealed by a multiomics analysis, and the characteristics of hydrochar related to the enhancement of AD.
海洋生物污损(biofouling)主要由微生物腐蚀与生物淤积造成;微生物被膜(biofilm)的形成为生物腐蚀提供了基础,也为生物淤积的发生创造了先决条件.抗生物附着材料是防止细菌定殖和微生物被膜形成的重要方式,其中低表面能防污涂层作为一种高效环保的抑膜方式,是近年来海洋防污损发展的重要方向之一.目前基于自然海域条件下,关于低表面能防污涂料对微生物被膜的抑制作用还有待进一步验证.基于已有方法的改进制备有机硅低表面能防污涂料;随后利用16S rRNA测序方法对微生物被膜的群落组成、多样性、互作网络及潜在功能进行分析.结果表明,与周围海水相比,低表面能防污涂料显著(P＜0.05)改变了微生物被膜的微生物组成,降低了鞘氨醇单胞菌等的定殖.Chao 1指数和β-多样性也受到低表面能材料的明显扰动.互作网络分析显示,低表面能防污涂层增加了微生物被膜群落的复杂性.此外,功能预测分析表明,该涂层表面微生物被膜生物群落的能量代谢与成膜能力相关功能基因的丰度显著降低(P＜0.05).综上,本研究制备了一种有机硅低表面能防污涂层,并从微生物学方面验证了其在自然海洋微生物被膜中的良好抑膜能力.
铁载体是海洋微生物获取铁元素的重要代谢因子,现有的一些研究推测海洋微生物铁代谢功能的发挥依赖群体效应,但海洋微生物群体行为的介导方式及其对铁载体功能的调节还未见揭示.为深入了解微生物的铁代谢特征,以藻际微生物为例,从中分离筛选产铁载体的细菌,并探讨群体感应信号(QS)对其合成的调控作用.利用稀释涂布法从甲藻赤潮样品中分离得到5株产铁载体的细菌,16S rRNA基因序列鉴定为新鞘氨醇杆菌(Novosphingobium sp.)、鞘氨醇单胞菌(Sphingomonas sp.)、寡养单胞菌(Stenotrophomonas sp.)、嗜水气单胞菌(Aeromonas hydrophila)和根瘤菌(Rhizobium arenae).铬天青S(CAS)检测法结合化学显色反应分析显示,细菌分泌的铁载体主要包括羧酸盐、异羟肟酸、儿茶酚和肠杆菌素.薄层色谱法(TLC)检测到4株细菌具有明显产群体感应信号的能力,信号分子主要为高丝氨酸内酯(AHLs)AHL-C8、AHL-C8-O以及AHL-10.为验证群体感应信号对铁载体的调节能力,以新鞘氨醇杆菌为代表构建AHL突变株,通过突变株与野生株的比较试验,发现AHL的缺失明显减少了铁载体的表达量,证实铁载体的分泌受到AHL信号的正向调节.考虑铁元素是藻际环境重要的微量元素,本研究结果提示微生物利用群体感应信号介导铁载体的表达,可能在藻菌关系中扮演着互利共生的作用.
利用可再生能源发电获得单细胞蛋白质,即"电转蛋白质(Power-to-Protein,PtP)",是生产单细胞蛋白质的绿色可持续途径.厌氧消化(anaerobic digestion,AD)可提供"电转蛋白质"过程中所需要的碳源以及部分氮源、微量元素等,通过厌氧消化与"电转蛋白质"技术相结合构建了一种可持续的蛋白质生产工艺,"厌氧消化-电转蛋白质(anaerobic digestion-Power-to-Protein,ADPtP)".本文介绍现有利用AD出料培养微生物获得单细胞蛋白质的工艺,分析引入PtP技术后的工艺效率与能耗,重点介绍ADPtP工艺的基础模式、过程中资源整合与利用.在电化学法还原模式中将沼气升级后培养甲烷氧化细菌操作简便易行且环境效益高,而以Wood-Ljungdahl碳转化途径设计的ADPtP工艺在安全性方面占优势.ADPtP工艺中,降低爆炸风险和提高转化效率是亟须解决的关键问题.另外,工艺中资源整合方式为电化学沼气升级、电化学消化液提氨、电解水产氢.未来,我国沼气产量与潜在储备量以及可再生能源发电量将为ADPtP提供发展基础,同时具有良好的政策环境和巨大的潜在蛋白质市场需求,因此该工艺在我国作为新型绿色蛋白质生产工艺而施行具有良好基础与应用前景.
植物根际促生菌(plant growth promoting rhizobacteria,PGPR)对促进植物生长和维持土壤健康具有重要意义,然而对其作用机制的认识仍存在不足,使其应用受限;近年来PGPR研究取得了不少进展,但尚缺乏综合解析.为此,针对PGPR,从定殖和促生机制两大方面进行国内外研究进展综述:在定殖机制方面,植物通过分泌有机物来招募特异的PGPR,随后PGPR通过趋化性和固体表面运动等机制感知根际分泌物并向根系迁移,最后通过植物、环境条件、竞争等进一步筛选定殖;在促生机制方面,PGPR通过分泌有机酸、产生螯合物、质子挤出或者酶促反应等机制促进氮、磷、铁等营养元素转化,并分泌植物激素和各种代谢产物来应对各种非生物胁迫和生物胁迫.总体而言PGPR-植物相互作用的过程多样而结果共赢.未来需要聚焦根际分泌物及PGPR代谢产物的作用方式与机理,更加关注PGPR微生物组在根际定殖、促生及缓解植物压力方面的作用,并积极推进PGPR的潜在应用,为PGPR的科学应用和农业可持续发展提供理论支撑.
Forest headwater streams are the monumental cement for relating habitats of the terrene and water. Nutri-ent dynamics of non-woody debris in stream can directly and indirectly regulate the cycle and transport of forest nutrients, for example, Ca and Mg. In the rainy season (from March to August) of 2021, we monitored the dyna-mics of Ca and Mg storage of non-woody debris in a typical headwater stream in a subtropical forest. The results showed that total Ca and Mg storage of non-woody debris per unit area of stream ranged from 178.1 to 890.5 mg·m-2 and 13.8 to 61.6 mg·m-2 during the rainy season, respectively. The Ca and Mg storages of non-woody debris per unit area of stream during the rainy season displayed a pattern of first increase and then decrease, and overall a decrease pattern. The storage varied significantly among different sites, with higher values in stream source than others. The total Ca and Mg storage of non-woody debris positively correlated with precipitation, but negatively with stream water alkalinity, temperature, and dissolved oxygen. The variation of riparian forest type (e.g., Castano-psis carlesii forests or mixed coniferous forests) and with or without tributaries did not affect the storage of Ca and Mg in stream non-woody debris. During the rainy season, total Ca and Mg storage of non-woody debris in the headwater stream from forest generally decreased over time, which was mainly controlled by the characteristics of rainfall and stream.
石油是世界上主要的能源之一,但不当的环境排放造成了严重的环境污染与危害,亟待进行修复.石油烃污染修复技术总体上可以归纳为物理、生物和化学修复技术.因技术手段的差异,其修复效率、技术成本及环境友好性均存在着较大的差异性及互补性.因此在实际工程中需要通过不同技术耦合以应对复杂的污染环境、提升修复效率并降低修复成本.通过梳理相关研究进展发现,微生物耦合化学修复是当下研究的热点之一.本文综述微生物修复的原理、修复微生物的种类及环境适应性;讨论微生物与化学氧化、光催化添加技术耦合修复石油烃污染土壤的特点及研究进展;发现耦合技术与单一的微生物修复技术相比,有着显著的优势.但不同的耦合技术其修复效率、成本、环境友好度及应用前景均存在较大的差异.根据环境条件、修复时间及石油烃组分特征针对性地选择微生物及化学技术进行耦合,是提升修复效率及降低成本的关键.最后,结合微生物与各化学方法的研究进展及局限对未来的技术发展进行展望,提出强化微生物修复能力及多技术综合运用是未来土壤修复技术的发展方向.
为探明伴生杂草的抑菌作用及其在土传病害生物防治中的应用价值,通过样方调查分析花椒伴生杂草的种类和群落结构,采用生长速率法测定研究优势伴生杂草对花椒根腐病病原菌的抑制情况.结果表明:20种伴生杂草的水提取液均能促进腐皮镰孢菌生长,其中地蚕、刺儿菜、粗毛牛膝菊、繁缕、灰菜、圆叶锦葵、香薷、苦苣菜、欧洲千里光、猪殃殃、蒲公英和野苜蓿具有显著(P＜0.05)促进作用,促进率在6.22％-16.61％之间;而地钱、黄花蒿、菊叶香藜、老鹳草、覆盆子和羽叶蓼这6种杂草的甲醇提取液能显著(P＜0.05)抑制腐皮镰孢菌的生长且存在明显浓度效应,抑制强度表现为地钱＞黄花蒿＞菊叶香藜＞老鹳草＞覆盆子＞羽叶蓼,培养3 d、4 d、5 d的抑菌率依次在17.5％-53.0％、16.2％-54.0％、15.9％-53.2％之间.可见,伴生杂草不仅通过资源竞争抑制花椒生长,还通过化感作用促进根腐病病原菌生长,是雨后椒园根腐病频发的原因之一;筛选出地钱、黄花蒿、老鹳草和菊叶香藜的甲醇提取液中含有抑菌活性物质,进一步开发植物源杀菌剂防治花椒根腐病提供了一定理论基础.
树干液流是树干木质部边材水分输导组织(导管或管胞)内的水分流动,其时滞是指在日变化节律上水分流动速率峰值与蒸腾驱动因子(主要气象因子)峰值之间存在的时间差.在运用气象环境要素监测值对树干液流速率(或通量)进行插值或模拟时,只有合理考虑液流与气象环境因子间的时滞效应,才能提高对液流测算的准确度.本文基于文献报道,对树干液流时滞的相关研究,诸如时滞特征所反映的树木生理生态特性进行分析和总结.时滞效应可以看作为气孔运动的结果,广泛存在于蒸腾作用等生理活动日动态变化中,是植物适应环境条件的表现.影响树干液流时滞特征的环境因素主要有太阳辐射、空气水汽压亏缺、空气温度和相对湿度以及土壤含水量等;内部因素包括树形及蒸腾特性等.时滞特征的差异与树木自身的生物学特性、生长阶段、分布区气候因素及季节等密切相关.目前关于树干液流的时滞效应虽然有很多研究,但大多聚焦于时滞的现象、时间长度及其发生的内外条件,对于生理生态机制的解析相对较少,相关研究结果也可能受到某种因素的限制而存在不确定性.建议未来进一步探究不同树种气孔调节特性及叶片不同功能形状与时滞效应的关系,解析时滞效应对环境因子响应的敏感性差异,在更大的区域尺度和气候变化范围内分析树种蒸腾耗水和时滞效应变化特征.
碳纳米点是一种能够调控植物生长发育的新型纳米材料,其植物生长调控机制及环境应用是一项研究热点.为揭示干旱条件下作物对碳纳米点的响应变化与机制,将氮掺杂功能性碳纳米点(nitrogen-doped functional carbon nanodots,N-FCNs)添加进土壤中,研究其对干旱胁迫下番茄生长发育、抗逆能力及土壤性质的影响.结果显示,3 mg/kg和10 mg/kg的N-FCNs均能够积极调控干旱条件下番茄的生长、抗逆及土壤性质,且3 mg/kg FCNs的作用效果更为显著.仅3 mg/kg的N-FCNs即能够将干旱条件下单株番茄果实数量和产量分别提高58.3％和30.6％,并且显著提高了水分利用效率(39.3％)、组织含水量(5.2％)、根系活力(15.3％)、脯氨酸水平(9.2％)、总叶绿素含量(26.9％)及谷胱甘肽水平(69.6％).3 mg/kg的N-FCNs还增强了植物抗氧化酶的活性,因而降低了36.0％的丙二醛产量.同时土壤含水量、有机质含量、有效氮含量和阳离子交换量分别被显著提高了62.6％、34.3％、6.6％和11.5％,土壤容重降低了4.6％.本研究表明:一方面,N-FCNs能够上调植物体内的酶催化、光合作用和养分吸收过程,缓解细胞过氧化损伤,从而增强番茄的抗旱能力;另一方面,N-FCNs能够通过改善土壤性质来有效缓解干旱胁迫对番茄生长发育和产量造成的抑制.因此,N-FCNs具有作为土壤添加剂提高干旱地区作物耐受性和生产力的潜力.
白鸡冠茶树是光照敏感型茶树,为挖掘与白鸡冠茶树在光照和遮阴条件下叶色变化相关的关键基因,选取遮阴和恢复光照处理白鸡冠第二叶5个时期的转录组数据,通过加权网络共表达分析(WGCNA)方法构建模块.6 580个差异表达基因构建的WGCNA网络被分为15个模块,其中darkseagreen模块与叶绿素含量相对值(SPAD值)显著正相关,honeydew模块和SPAD值显著负相关.GO富集结果表明darkseagreen模块显著富集到初级代谢过程的调节和压力响应等过程,而honeydew模块在叶绿体和单器官代谢等过程显著富集.从darkseagreen模块和honeydew模块中发掘到数个潜在核心基因,并采用Cytoscape对darkseagreen模块和honeydew模块的基因绘制互作网络图,进而从darkseagreen模块筛选出2个基因(CSS0019351.CSS0045917)和2个转录因子(CSS0046793和CSS0018417),在honeydew模块筛选出2个基因(CSS0031492和CSS0036305)和1个转录因子(CSS0023211).本研究通过WGCNA方法筛选出2个具有生物学意义的模块,进一步挖掘得到的7个关键基因和转录因子与叶绿素合成和叶绿体发育密切相关.
厌氧消化是实现有机废弃物资源化最有效的技术之一,实现形式是产生生物沼气.作为一种清洁能源,生物沼气可以有效减少化石燃料的使用,进而减少温室气体的排放.产甲烷古菌位于厌氧发酵链末端,是生物沼气主要成分甲烷的直接生产者.在厌氧消化系统中,产甲烷古菌与发酵链前端微生物以及各种天然和人工电子传递体存在着活跃的电子互营过程,对于维持厌氧消化系统的稳定性和改善生物沼气的生成效率具有重要作用.本文综述近年来报道的在强化厌氧消化过程中常用的铁基与碳基电子传递体与产甲烷古菌的相互作用机制,着重介绍两类电子传递体通过自身氧化还原反应或物理性质与产甲烷古菌细胞膜上的氢酶和细胞色素c进行电子互营的微观作用机理,分析两类电子传递体通过参与胞外电子传递过程与产甲烷古菌能量代谢可能存在的耦合机制,其中乙酸型产甲烷古菌基于电子歧化传递在进行胞外三价铁呼吸过程中存储能量,从而增强产甲烷代谢,改变了目前对甲烷生成的生化和生态学理解,极大推进了产甲烷古菌与胞外电子传递体相互作用的研究.产甲烷古菌胞外电子传递路径的不清晰和其细胞膜上蛋白功能的不确定是制约产甲烷古菌与电子传递体相互作用机制研究的重要因素.因此提出利用快速发展的分子生物学如基因敲除以及荧光标记等技术进一步深入研究产甲烷古菌与电子传递体相互作用机制的可能性和新思路.
为研究杂交籼稻骨干亲本Wx和ALK基因的等位变异与水稻蒸煮食味品质的关联性及其理想组合方式,对34份杂交籼稻骨干亲本的稻米直链淀粉含量(AC)、胶稠度(GC)、碱消值(ASV)与其Wx和ALK基因等位变异的关联性进行分析.结果显示:34份材料的Wx基因序列包括41个多态性位点,被划分为6种单倍型,共有31个位点与AC和GC呈极显著关联,其中Ex1-47位点的关联系数最大.Wx1单倍型在Int1-1位点与Wxa相同,与中高AC和硬GC极显著关联;Wx2单倍型在Int1-1和Ex1-47位点与Wxhp相同,与中高AC和中等GC极显著关联;Wx3、Wx4、Wx5和Wx6单倍型在Int1-1位点与Wxb相同,与较低AC和软GC极显著关联.34份材料的ALK基因包括49个多态性位点,被划分为5种单倍型,共有24个位点与ASV呈显著或极显著关联,其中Ex8-864/865位点的关联系数最大.ALK1、ALK2、ALK3和ALK4单倍型在Ex8-733和Ex8-864/865位点与ALKG一致,其中ALK1、ALK3和ALK4与低ASV极显著关联,ALK2与中高ASV极显著关联.ALK5单倍型在Ex8-733和Ex8-864/865位点与ALJKT一致,与高ASV极显著关联.34份材料共分为10个Wx和ALK基因单倍型组合,不同单倍型组合间的AC、GC和ASV均存在显著或极显著差异,其中Wx3-ALK5和Wx5-ALK5单倍型组合表现为较低AC、软GC和高ASV.本研究表明Wx3-ALK5和Wx5-ALK5单倍型组合是优质稻米蒸煮食味品质的理想组合方式.
微塑料对土壤动物的生态毒性被广泛认知,但多数研究关注的是传统难降解微塑料,如聚乙烯(polyethylene,PE)等.可生物降解微塑料对土壤动物的毒性效应知之甚少.通过室内暴露试验,比较研究了不同浓度(1％和10％,w/w)PE微塑料和可生物降解聚乳酸(polylactic acid,PLA)微塑料对赤子爱胜蚓(Eisenia fetida)的生态毒性.结果表明,与对照相比,PE和PLA处理均会导致蚯蚓体重损失和一定的死亡率(22％-24％).PE和PLA均会诱导蚯蚓发生氧化应激反应:超氧化物歧化酶(SOD)活性增加,过氧化物酶(CAT)和谷胱甘肽硫转移酶(GST)活性降低.组织病理学分析表明,PLA比PE表现出更严重的表皮损伤、肠道损伤和精囊损伤,高浓度时效应更为显著.本研究表明,传统难降解微塑料和可生物降解微塑料均可对蚯蚓产生毒性效应,可降解微塑料并不比传统微塑料更具有生态友好性.
厨余垃圾厌氧消化液有机酸含量高,可作为一种经济有效的产品来取代市场的反碳化碳源.为了解其反硝化表现和微生物学机制,采用序批式活性污泥法(SBR)反硝化工艺进行脱氮,添加模拟厨余垃圾厌氧发酵液中有机酸组分的混合有机酸(乙酸钠:丙酸钠:丁酸钠以7:1:2比例混合),逐渐提高进水的硝酸盐浓度(以N计,100-1 600 mg/L),研究此过程的脱氮性能、微生物群落结构及功能基因的变化,并揭示系统中的碳氮代谢情况.结果显示,以混合有机酸为碳源的系统具有良好的脱氮效率,最大反硝化速率(以N计)为111.95 mg L-1 h-1.16S rRNA测序结果显示微生物群落的a多样性逐渐减少,功能微生物Rhodocyclaceae、Thauera和Blvii28_wastewater-sludge group高度富集,表明微生物的功能集中性随硝氮负荷增加而增强.荧光定量PCR(qPCR)和宏基因组测序结果表明,长期添加混合挥发酸驯化的污泥中反硝化功能基因nosZ高度富集,这对减少温室气体排放有着重要意义.可见,混合有机酸是一种优良的反硝化脱氮碳源.
In the context of global warming， the "carbon neutrality" strategy has a profound impact on the development of various industries. As one of the industries with the highest energy consumption and carbon emissions， sewage treatment has also attracted much attention for its "carbon neutral" operation. Based on 369 articles in the Web of Science Core Collection （WOS） and China National Knowledge Infrastructure （CNKI） databases， this paper used CiteSpace， VOSviewer and HistCite software to conduct bibliometric and knowledge graph analysis. The development overview， research status and frontier hotspots in the field of carbon neutrality in sewage treatment during 2008—2022 are reviewed. The results showed that the research in the field of carbon neutrality in wastewater treatment is greatly influenced by policies. The signing of the Paris Agreement in 2015 and the proposal of China’s "carbon neutrality" strategy in 2020 have promoted the development of this field. The mainstream journals in the field of water environment in China and the world have paid great attention to carbon neutralization of sewage treatment， and carbon neutralization of sewage treatment has become a research hotspot in the field of water environment. Most developed countries and some developing countries have participated in the research on carbon neutrality in sewage treatment. There is close cooperation in research between countries， and Chinese researchers are the main force in this field. Greenhouse gas management， microalgae carbon capture and energy recovery and utilization in the process of sewage treatment are the current research hotspots. The combination of traditional biochemical treatment technology and low-carbon technology in other fields， methane recycling and N 2 O emission control are important directions.
为探讨地震前后典型小流域的景观格局变化特征,以龙溪河流域为研究区,选取2005年、2009年、2011年、2015年四期高分辨率遥感影像为数据源.从斑块类型和景观两个水平,运用13种景观格局指数,通过Fragstats景观指数计算软件,对龙溪河小流域震前(2005)、震后初期(2009)、震后3年(2011)和震后7年(2015)等4个不同时期景观格局进行测度,并利用ArcGIS软件建立缓冲区,将4个时段的遥感影像划分为人类活动区域和自然区域,研究该流域在地震前后的景观生态格局演变特征.结果表明:(1)2005年-2015年受地震灾害影响各斑块面积均发生不同程度的改变,其中,林地景观斑块面积占比均最大,震前91.35％降至78.41％,震后3年增加至86.06％,震后7年继续增加至90.46％,构成龙溪河流域景观基质.林地斑块面积地震前后差异较小;耕地、建设用地景观斑块面积呈持续减小趋势;灌草景观斑块面积呈先减后增再减的波动减小趋势;交通用地呈持续增加趋势;沟道、裸地、地质灾害斑块面积呈先增后减的趋势.(2)2005-2015年,都江堰龙溪河流域的景观类型变化以灌草、地质灾害和林地的空间转换为主.2005-2009年景观面积转移特征为:灌草转变为林地,林地转变为地质灾害;2009年-2011年转移特征为:灌草转变为林地,林地转变为地质灾害;2011年-2015年转移特征为:灌草、地质灾害转变为林地,林地转变为灌草、地质灾害;2005年-2015年整体转移特征为:灌草转变为林地,林地转变为地质灾害、灌草.(3)震后林地、灌草、交通用地、裸地、地质灾害的景观破碎程度均较高,受到较强的人为干扰.林地与地质灾害受地震影响最为显著,边界被割裂的程度较深,景观破碎度高,边界效应较明显,但林地作为景观基质聚合度较其余景观斑块高.自然区域中,人为干扰相对较小,震后地质灾害的斑块密度与边缘密度均大幅减少,且低于人类活动区,这表明地震及次生灾害对自然区域的影响较小,且无人类干扰时可以较好地恢复.(4)震后SHEI与SHDI呈增长趋势,CONTAG呈减小趋势,表明龙溪河流域各个景观类型面积差异性减小,斑块类型增加,景观类型的优势度降低,景观水平异质性增强,景观连通性降低.自然区域景观分布较人类活动区域分布聚集且邻接性高,人类活动区域景观的分布受制于地形因子的作用.研究发现"5.12"大地震破坏了龙溪河流域的原有景观格局,泥石流、滑坡等次生灾害破坏其中原有斑块,灾后人类活动与景观格局的变化联系密切.本研究可为龙溪河流域的生境恢复与灾后重建工作提供依据,并为其生态保护和可持续发展提供理论基础和科学建议.
To explore the effect of long-term cultivation of Yunnan large leaf tea （Camellia sinensis var. assamica） on the diversity of soil fungal， we selected four tea tree areas （three samplings set for each area） with tree ages of 10 years （10 a）， 40 years （40 a）， 80 years （80 a）， and more than 100 years （100 a） were selected from Bindaolaozhai tea garden in Shuangjiang county， Yunnan province，， and took adjacent forest areas without tea planting history as the control （CK）， We collected the topsoil （0-20 cm） and the fungus group was identified by Illumina Novaseq high-throughput sequencing technology， to analyze the impact of tea planting years on the structure and diversity of soil fungal community， and to explore the relationship between fungal community and soil chemical factors. The results showed that with the increase of tea planting years， the diversity index of soil fungal decreased at first and then increased， and then reached the lowest in 40 years， and there were significant difference in difference planting years （P ＜ 0.05）; Spearman correlation analysis showed that soil fungal community diversity was mainly affected by available potassium， alkali-hydrolyzed nitrogen and total potassium， soil organic matter and soil pH. The relative abundances of domain phylum Ascomycota and Basidiomycota was greater than 10%， Ascomycota decreased at first and then increased， but Basidiomycota increased at first and then decreased; Non-metric multidimensional scaling analysis and analysis of similarities analysis showed that there were significant differences on soil fungal communities in different tea planting years and separated in spatial （R = 0.56， P = 0.0001）. Linear discriminant analysis effect size analysis further showed that there were significant differences in different tea planting years on microbial species. Spearman correlation analysis showed that soil fungal community diversity was mainly affected by available potassium， alkali-hydrolyzed nitrogen， and total potassium. In summary， long-term cultivation of Yunnan large leaf tea has changed soil chemical properties， which resulted in changes in soil fungal community composition and diversity. 40 years of tea planting was the key period of significant changes in soil fungal community.
拟除虫菊酯类农药由于其高疏水性和高分子质量,难以被微生物吸附、摄取和降解,如何提高此类底物的生物可及性是环境生物修复的关键之一.利用细胞表面展示技术将拟除虫菊酯降解酶展示到大肠杆菌细胞表面,构建新型全细胞催化剂,克服拟除虫菊酯类农药的吸附-摄取限制.将丁香假单胞菌冰核蛋白InaK的N-末端作为锚定基序与来自铜绿假单胞菌GF31的拟除虫菊酯降解酶基因融合,转化大肠杆菌Rosetta-gami,构建全细胞催化剂.结果表明在0.05 mmol/L的IPTG条件下诱导培养12 h后,该全细胞催化剂的氨基肽酶活性达到0.25 U/OD600/mL,对高效氯氰菊酯农药底物的降解速率达到35.9 μmol L-1 d-1,且对5种常用拟除虫菊酯类农药均具有降解能力.通过细胞的分级分离和免疫荧光分析确定了功能蛋白在细胞膜上的正确位置.该全细胞催化剂经过10次重复反应,残余活性仍能保持在70％以上,具有较好的稳定性.本研究实现了拟除虫菊酯降解酶在大肠杆菌细胞表面上的功能性展示,为高疏水性有机农药的环境修复提供了一种方法.
To reveal Nitrogen and phosphorus resorption characteristics of Robinia pseudoacacia and their driving factors in hilly and gully regions， five different stand ages of Robinia pseudoacacia plantations in Zhifanggou Watershed in the hilly and gully region， including 13-years-old， 17-years-old， 21-years-old， 33-years-old and 43-years-old， were selected as the objects. We compared N and P resorption characteristics， the content of C， N， P and their ecological stoichiometry in soil， fresh leaf and senesced leaf. We analyzed the relationship between nutrient resorption efficiencies （N and P） and the C : N : P stoichiometry in soil or leaf （fresh leaf， senesced leaf）. Results showed that N:P was more than 16 in fresh leaf at each age， with a range of 24.52-30.85. The growth of R. pseudoacacia was mainly restricted by P. The N and P content in fresh leaf were significantly higher than those in senesced leaf for R. pseudoacacia at different stand ages， while C : N and C : P in fresh leaf were significant lower than those in senesced leaf for R. pseudoacacia at different stand ages. With increasing stand ages， N and P resorption efficiency showed a tendency to initially decreased and then increased， and were the lowest at 21-years.The mean value of N and P resorption efficiency were 52.32% and 68.03%， with a range of 41.2%-57.1% and 49.9%-79.3%， respectively. N resorption efficiency showed a significant negative response to soil total N and N : P， while there was no significant correlation between P resorption efficiency and soil total P. N and P resorption efficiency showed a significant positive response to C : N and N : P in senesced leaf. This study indicated that the growth of R. pseudoacacia was limited by P and mature leaf could improve the recovery efficiency of N and P in senesced leaf to maintain the growth of R. pseudoacacia.
