不同森林恢复类型对土壤微生物群落的影响

为了评价不同森林恢复类型与方式对南方红壤丘陵区退化生态系统土壤微生物群落的影响,借助氯仿熏蒸法、平板涂抹法和BIOLOG检测法,比较研究了4种森林恢复类型土壤微生物的群落特征．结果表明,4种森林恢复类型土壤微生物生物量碳、细菌数量差异显著,2项指标均以天然次生林土壤最高,人工林次之,荒地最差;碳源平均颜色变化率(AWCD法)和微生物代谢多样性指数(丰富度和多样性)在5种植被类型的土壤中也有明显差异,其趋势与微生物量碳、细菌数量基本相同;天然次生林土壤微生物群落利用碳源的整体能力和功能多样性比人工林和荒地强．相关分析表明,0～20和20～40cm土壤微生物的代谢多样性与根系生物量紧密相关(r=0．933,P<0．05;r=0．925,P<0．05)．自然恢复更有利于改善土壤微生物的结构和功能．     

恩诺沙星对土壤微生物群落功能多样性的影响

为了评价恩诺沙星(enrofloxacin)对土壤微生物群落的影响,借助BIOLOG检测法比较了不同浓度恩诺沙星影响下的土壤微生物的群落特征。结果表明,各添加药物组与空白对照组的土壤微生物群落代谢多样性差异显著(P<0.05),空白对照组土壤微生物在BIOLOG微平板上的平均每孔颜色变化率(AWCD)和微生物代谢多样性指数(丰富度和多样性)显著高于添加药物组;药物显著影响微生物群落对BIOLOG微平板中碳源的利用能力,较低浓度的恩诺沙星(0.01μg/g)就显著影响了土壤微生物群落对α-Ketobutyric Acid、L-Phenylalanine、1-Erythritol、D-Xylose等碳源的利用代谢能力(P<0.05),且土壤微生物群落利用各类碳源的能力随药物浓度加大而降低。由此可见,恩诺沙星在土壤中残留时对土壤微生物的影响不容忽视。     

环丙沙星对土壤微生物量碳和土壤微生物 群落碳代谢多样性的影响

采用氯仿熏蒸浸提法和Biolog法,分析环丙沙星作用下的土壤微生物量碳和微生物群落碳代谢多样性,以揭示环丙沙星在环境中残留对土壤微生物学性状的影响.结果表明,环丙沙星(wCIP≥0.1 μg/g)对土壤微生物量碳含量影响显著(P＜0.05),土壤中环丙沙星浓度愈高,微生物量碳含量愈低,100μg/g的环丙沙星处理使土壤微生物量碳含量下降58.69％.环丙沙星对土壤微生物群落碳代谢功能影响显著,环丙沙星降低了土壤微生物对碳水化合物、羧酸、氨基酸、聚合物、酚类和胺类的碳源利用率;环丙沙星(wCIP≥0.1 μg/g)显著影响了土壤微生物群落碳源代谢强度和代谢多样性,但不同浓度的环丙沙星对土壤微生物群落碳代谢功能的影响不同,0.1、1、10 μg/g的环丙沙星处理对土壤微生物群落碳代谢功能的影响主要表现在处理前期(用药第7天、21天),这种影响在处理后期(用药第35天)表现不明显,100μg/g的环丙沙星在用药的前期和后期均显著影响土壤微生物群落碳代谢功能,土壤中环丙沙星积累到该浓度可能对土壤微生物群落碳代谢功能产生难以逆转的长期影响.     

Effects of grassland species on decomposition of litter and soil microbial communities

Decomposition of litter is greatly influenced not only by its chemical composition but also by activities of soil decomposers. By using leaf litter from 15 plant species collected from semi-natural and improved grasslands, we examined (1) how interspecific differences in the chemical composition of litter influence the abundance and composition of soil bacterial and fungal communities and (2) how such changes in microbial communities are related to the processes of decomposition. The litter from each species was incubated in soil of a standard composition for 60 days under controlled conditions. After incubation, the structure of bacterial and fungal communities in the soil was examined using phospholipid fatty-acid analysis and denaturing gradient gel electrophoresis. Species from improved grasslands had significantly higher rates of nitrogen mineralization and decomposition than those from semi-natural grasslands because the former were richer in nitrogen. Litter from improved grasslands was also richer in Gram-positive bacteria, whereas that from semi-natural grasslands was richer in actinomycetes and fungi. Nitrogen content of litter also influenced the composition of the fungal community. Changes in the composition of both bacterial and fungal communities were closely related to the rate of litter decomposition. These results suggest that plant species greatly influence litter decomposition not only through influencing the quality of substrate but also through changing the composition of soil microbial communities.     

间作栽培对连作马铃薯根际土壤微生物群落的影响

连作严重影响了作物的产量和品质,而土壤微生物群落结构与功能对土壤生态系统和植物健康至关重要。以连作10a土壤为基质,单作马铃薯为对照,采用磷脂脂肪酸(Phospholipid fatty acids)、BIOLOGA技术和真菌形态学鉴定方法,研究了玉米、蚕豆与马铃薯间作模式下土壤微生物群落结构、功能和丛植菌根(Arbuscular Mycorrhizal)真菌对土壤环境变化的响应。结果表明:间作调控下,马铃薯根际土壤微生物主要类群结构发生显著改变;玉米间作马铃薯,土壤微生物群落总生物量降低,但群落功能多样性提高,促进了以羧酸类、多聚化合物、芳香类化合物、氨基酸类化合物为碳源的微生物类群代谢活性增强;蚕豆间作增加了土壤微生物总生物量,仅促进了以碳水化合物为碳源的微生物类群代谢活性。间作改变了作物根际土壤AM真菌的种、属数,AM真菌多样性降低,优势种由明球囊霉、地球囊霉转变为玉米间作体系里的福摩萨球囊霉、球泡球囊霉;蚕豆间作体系里福摩萨球囊霉和疣状无梗囊霉是优势种。间作栽培下AM真菌优势种群的变化可能受植物间的共生关系、微生物结构与功能等因素的制约。间作条件下,玉米显著影响了马铃薯根际土壤微生物群落功能多样性,而蚕豆则显著改变了微生物群落结构多样性;玉米、蚕豆对马铃薯根际土壤微生物群落功能与结构变化的影响不同步;间作调控后持续的土壤微生物群落结构与功能观察才有助于解释土壤微生物结构变化引起的功能响应。     

Patterns and governing forces in aquatic microbial communities

In this review we survey recent publications employing molecular techniques to investigate the distribution of microbial species in aquatic environments. We analyzed the occurrence of microbial phyla in freshwater and marine habitats and observed patterns of distribution that could be explained by the adaptation of microorganisms to physical and biological parameters that vary in aquatic habitats. The gram-positive bacteria, the Verrucomicrobiales and the - and -subdivisions of the Proteobacteria are distributed throughout a range of aquatic habitats, while other phylogenetic groups appear to be adapted to more narrowly defined environmental niches such as anoxic water and sediments (-Proteobacteria) or floating aggregates (Cytophaga-Flexibacter-Bacteroides phylum). -proteobacterial sequence types have been detected throughout freshwater habitats, but these organisms are largely absent from open ocean environments. Within several of these divisions, clusters of closely related small sub unit ribosomal RNA sequence types have been detected in geographically disparate environments, suggesting that some microbial species are globally distributed. In addition to physical variables such as salinity and pH, biological variables also influence microbial community composition. This was illustrated by changes that occurred in the eukaryotic and bacterial species composition in laboratory mesocosms after a viral outburst. We conclude that physical and biological forces govern the composition of aquatic microbial communities and result in divergent evolutionary histories of the indigenous microbial species.     

转抗菌肽D烟草对土壤微生物群落的影响

采用RAPD分子标记技术研究了种植转抗菌肽D烟草的土壤环境中微生物群落遗传多样性的变化,同时用传统平板培养法研究了土壤中可培养微生物在数量上的变化。RAPD分析结果表明,转抗菌肽D烟草与非转基因烟草根围微生物的遗传多样性相关指数并没有显著差异。培养计数结果表明,转抗菌肽D烟草与非转基因烟草根围可培养细菌在数量上有极显著差异,可培养真菌数量有显著减少,可培养放线菌的数量没有显著差异。说明转抗菌肽D烟草可能抑制了病原细菌及其根围相关的微生物,但是不影响微生物的遗传多样性。     

转基因水稻对土壤微生物群落结构及功能的影响

以非转基因水稻为对照,以变性梯度凝胶电泳(DGGE)和Biolog技术为手段,研究了2种转基因水稻对土壤微生物群落结构及功能的影响。结果显示:转基因水稻仅在生长发育旺盛期对土壤细菌数量有显著影响;且不同品种转基因水稻土壤微生物间的遗传距离大于转基因水稻与对照间土壤微生物的距离,即2个转基因水稻品种对土壤微生物群落遗传多样性的影响均不显著;在水稻抽穗期,2种转基因水稻与其对照的土壤微生物群落在72h时的平均光密度呈现显著差异,而到了成熟期则差异不显著。土壤微生物群落多样性指数和均匀度指数也表现出类似趋势。本试验证明,在水稻生长发育旺盛时期,Mclntosh指数(u)是一个有效区分转基因水稻和非转基因水稻土壤微生物群落多样性的指标。     

Adaptation of aquatic microbial communities to hg stress

The mechanism of adaptation to Hg in four aquatic habitats was studied by correlating microbially mediated Hg volatilization with the adaptive state of the exposed communities. Community diversity, heterotrophic activity, and Hg resistance measurements indicated that adaptation of all four communities was stimulated by preexposure to Hg. In saline water communities, adaptation was associated with rapid volatilization after an initial lag period. This mechanism, however, did not promote adaptation in a freshwater sample, in which Hg was volatilized slowly, regardless of the resistance level of the microbial community. Distribution of the mer operon among representative colonies of the communities was not related to adaptation to Hg. Thus, although volatilization enabled some microbial communities to sustain their functions in Hg-stressed environments, it was not mediated by the genes that serve as a model system in molecular studies of bacterial resistance to mercurials.     

The invasive potential of a hybrid species: insights from soil chemical properties and soil microbial communities

作为适应性进化,入侵物种与本土物种的自然杂交威胁着全球生物多样性。然而,杂交种的潜在入侵机制尚未得到系统研究,尤其是在土壤化学性质和土壤微生物群落方面。在一个为期两年的田间试验中,对入侵种南美蟛蜞菊(Sphagneticola trilobata)和杂交蟛蜞菊(南美蟛蜞菊与本地蟛蜞菊S. calendulacea杂交)的土壤微生物群落、土壤解钾菌和解磷菌菌落数、土壤酶活性以及叶片光饱和速率进行了测定。结果表明：杂交蟛蜞菊土壤可溶性有机碳和解磷菌菌落数显著高于南美蟛蜞菊和本地蟛蜞菊。土壤酸性磷酸酶、总PLFA、细菌PLFA、真菌PLFA、纤维素酶、脲酶在三种处理间无显著差异。杂交蟛蜞菊光饱和光合速率、光合氮、磷和钾利用效率显著高于入侵种南美蟛蜞菊,但与本地蟛蜞菊无显著差异。杂交蟛蜞菊总生物量和根生物量显著高于本地蟛蜞菊。因此,与本地蟛蜞菊相比,杂交蟛蜞菊仍然有较高的入侵性,其未来可能加剧本地蟛蜞菊的灭绝。     

Identifying microbial drivers promoting plant growth on soil amended with composted aquatic plant: insight into nutrient transfer from aquatic to terrestrial systems

Limnology - Effects of applying composted aquatic plants on soil chemistry, soil microbes (fungi and bacteria), and the growth of cultivated plant were demonstrated. To identify drivers promoting...     

不同熏蒸剂对草莓连作土壤养分和微生物群落的影响

【背景】草莓连年栽培导致土传病害问题突出,施用熏蒸剂进行土壤消毒因效果显著得以广泛应用。但不同熏蒸剂对土壤病原微生物的影响存在较大差异,同时对非靶标微生物和土壤理化性质也会有不同程度的影响。【目的】明确不同熏蒸剂对草莓连作土壤养分和土壤细菌、真菌群落结构的影响,为合理选择熏蒸剂提供科学依据。【方法】以连作土壤为材料设置5个处理：未熏蒸、石灰氮熏蒸、石灰熏蒸、棉隆熏蒸、威百亩熏蒸,测定熏蒸处理后土壤养分含量;采用PacBio测序平台分析土壤微生物多样性的变化。【结果】石灰氮和威百亩处理均增加了碱解氮含量,降低了有机质、有效磷和速效钾含量;棉隆处理土壤中各养分含量均增加;石灰处理除有机质含量增加外,碱解氮、有效磷和速效钾含量均降低;棉隆、石灰和威百亩处理显著降低pH值。5个处理草莓连作土壤样本中获得了1 164个细菌OTU和444个真菌OTU。细菌多样性和丰富度分析发现,4种熏蒸剂处理均增加了土壤细菌群落的丰富度,石灰氮、石灰和威百亩处理增加了土壤细菌菌落的多样性。4种熏蒸剂处理真菌菌落的丰富度低于对照;石灰、棉隆处理真菌菌落的多样性高于对照和石灰氮、威百亩处理低于对照,但差异不显著。在物种组成分析中,从门水平看,变形菌门(Proteobacteria)和芽单胞菌门(Gemmatimonadetes)为优势细菌门;与对照相比,石灰氮、石灰、棉隆处理变形菌门相对丰度增高,威百亩处理相对丰度降低。4种处理均降低了芽单胞菌门的相对丰度。其他门类中,4种处理均增加了浮霉菌门(Planctomycetota)、疣微菌门(Verrucomicrobia)的相对丰度。优势细菌群落分析表明土壤熏蒸减少了芽单胞菌属(Gemmatimonas)、藤黄单胞菌属(Luteimonas)、中慢生根瘤菌属(Mesorhizobium)等细菌的相对丰度,增加了噬几丁质菌属(Chitinophaga)、苍白杆菌属(Ochrobactrum)的相对丰度。子囊菌门(Ascomycota)为优势真菌,石灰氮、石灰、棉隆、威百亩4种处理均增加了子囊菌门的相对丰度。另外还检测到引起草莓根部土传病害的枝孢属(Cladosporium)和镰刀菌属(Fusarium)病菌,熏蒸处理后均降低了枝孢属和镰刀菌属的相对丰度,其中枝孢属在石灰氮、石灰、棉隆、威百亩处理中分别降低了1.35%、1.11%、0.90%和1.31%,镰刀菌属分别降低了0.71%、0.85%、0.19%和0.65%,但差异不显著。4种土壤熏蒸剂均增加了有益真菌毛壳菌属(Chaetomium)的相对丰度。【结论】采用熏蒸剂处理连作土壤改变了微生物群落构成,减少或灭杀土壤中的大部分致病菌属,起到有效防治草莓土传病害的作用,但不能灭杀所有病菌,而且对有益菌和土壤理化性质有不同程度的影响,因此处理后补充有益微生物非常关键。根据对病原菌的灭杀效果,石灰氮、威百亩处理的效果优于其他处理,可作为轮换施用的熏蒸剂,本试验条件下,棉隆是一种弱的处理剂。     

Invisible invaders: non-pathogenic invasive microbes in aquatic and terrestrial ecosystems

Although the number of studies on invasive plants and animals has risen exponentially, little is known about invasive microbes, especially non-pathogenic ones. Microbial invasions by viruses, bacteria, fungi and protists occur worldwide but are much harder to detect than invasions by macroorganisms. Invasive microbes have the potential to significantly alter community structure and ecosystem functioning in diverse terrestrial and aquatic ecosystems. Consequently, increased attention is needed on non-pathogenic invasive microbes, both free-living and symbiotic, and their impacts on communities and ecosystems. Major unknowns include the characteristics that make microbes invasive and properties of the resident communities and the environment that facilitate invasions. A comparison of microbial invasions with invasions of macroorganisms should provide valuable insights into general principles that apply to invasions across all domains of life and to taxon-specific invasion patterns. Invasive microbes appear to possess traits thought to be common in many invasive macroorganisms: high growth rate and resource utilization efficiency, and superior competitive abilities. Invading microorganisms are often similar to native species, but with enhanced performance traits, and tend to spread in lower diversity communities. Global change can exacerbate microbial invasions; therefore, they will likely increase in the future.     

Impact of fumigants on soil microbial communities.

Agricultural soils are typically fumigated to provide effective control of nematodes, soilborne pathogens, and weeds in preparation for planting of high-value cash crops. The ability of soil microbial communities to recover after treatment with fumigants was examined using culture-dependent (Biolog) and culture-independent (phospholipid fatty acid [PLFA] analysis and denaturing gradient gel electrophoresis [DGGE] of 16S ribosomal DNA [rDNA] fragments amplified directly from soil DNA) approaches. Changes in soil microbial community structure were examined in a microcosm experiment following the application of methyl bromide (MeBr), methyl isothiocyanate, 1,3-dichloropropene (1,3-D), and chloropicrin. Variations among Biolog fingerprints showed that the effect of MeBr on heterotrophic microbial activities was most severe in the first week and that thereafter the effects of MeBr and the other fumigants were expressed at much lower levels. The results of PLFA analysis demonstrated a community shift in all treatments to a community dominated by gram-positive bacterial biomass. Different 16S rDNA profiles from fumigated soils were quantified by analyzing the DGGE band patterns. The Shannon-Weaver index of diversity, H, was calculated for each fumigated soil sample. High diversity indices were maintained between the control soil and the fumigant-treated soils, except for MeBr (H decreased from 1.14 to 0.13). After 12 weeks of incubation, H increased to 0.73 in the MeBr-treated samples. Sequence analysis of clones generated from unique bands showed the presence of taxonomically unique clones that had emerged from the MeBr-treated samples and were dominated by clones closely related to Bacillus spp. and Heliothrix oregonensis. Variations in the data were much higher in the Biolog assay than in the PLFA and DGGE assays, suggesting a high sensitivity of PLFA analysis and DGGE in monitoring the effects of fumigants on soil community composition and structure. Our results indicate that MeBr has the greatest impact on soil microbial communities and that 1,3-D has the least impact.     

干旱对不同花椒种植模式下土壤微生物和线虫群落的影响

随着全球气候变暖, 我国岷江上游干旱区面积呈现增加的趋势。花椒(Zanthoxylum bungeanum)是岷江上游重要的经济树种之一, 对当地经济和社会发展起着重要作用, 提高花椒生态系统应对干旱干扰已成为迫切的问题。本研究设置了花椒单作、花椒-苜蓿(Medicago sativa)间作和花椒-大豆(Glycine max)间作3种种植模式, 在2015年8月对每种种植模式模拟干旱30 d, 每种种植模式包括干旱和对照处理, 在模拟干旱结束后、恢复15 d、30 d和45 d后分别采集土壤样品, 分析土壤化学性质、土壤微生物和线虫群落, 以探究花椒林下豆科植物能否缓和干旱的遗留效应对土壤化学性质和土壤生物的影响。重复测量方差分析表明: 在花椒单作模式下, 干旱恢复45 d后土壤硝态氮含量显著高于对照, 微生物量和真菌/细菌比与对照无显著差异, 线虫密度与对照无显著差异, 但线虫功能团没有恢复到对照水平; 在花椒-苜蓿间作模式下, 干旱恢复45 d后土壤含水量、铵态氮、硝态氮、溶解性有机碳、溶解性有机氮、微生物量、真菌/细菌比、线虫密度和线虫功能团组成与对照无显著差异, 但植食性线虫属Boleodorus相对多度显著高于对照; 在花椒-大豆间作模式下, 干旱恢复45 d后土壤含水量、铵态氮、硝态氮、溶解性有机碳、溶解性有机氮、微生物量和真菌/细菌比与对照无显著差异, 但线虫密度和功能团组成与对照有显著差异。在3种花椒种植模式中, 花椒-苜蓿间作模式下干旱的遗留效应对土壤养分和生物的影响最小。因此, 在干旱背景下, 花椒林下间作豆科植物可以加快土壤养分、土壤微生物和线虫群落的恢复, 进而有利于目标作物生长。     

内蒙古草原典型植物对土壤微生物群落的影响

为了分析内蒙古草原不同植物物种对土壤微生物群落的影响, 采用实时荧光定量PCR (real-time PCR)以及末端限制性片段长度多态性分析(terminal restriction fragment length polymorphism, T-RFLP)等分子生物学技术, 测定了退化-恢复样地上几种典型植物的根际土壤和非根际土壤中细菌和真菌的数量及群落结构。结果表明, 不同植物物种对根际和非根际细菌及根际真菌数量均有显著影响。根际土壤中的细菌和真菌数量普遍高于非根际土壤, 尤其以真菌更为明显。对T-RFLP数据进行多响应置换过程(multi-response permutation procedures, MRPP)分析和主成分分析(principal component analysis, PCA), 结果表明, 大多数物种的根际细菌及真菌的群落结构与非根际有明显差异, 并且所有物种的真菌群落可以按根际和非根际明显分为两大类群。此外, 细菌和真菌群落结构在一定程度上存在按物种聚类的现象, 以细菌较为明显。这些结果揭示了不同植物对土壤微生物群落的影响特征, 对理解内蒙古草原地区退化及恢复过程中植被演替引起的土壤性质和功能的变化有一定的帮助。     

Estimating ecotoxicological risk and impact using indigenous aquatic microbial communities

Emphasis has increased on accuracy in predicting the effect that anthropogenic stress has on natural ecosystems. Although toxicity tests low in environmental realism, such as standardized single species procedures, have been useful in providing a certain degree of protection to human health and the environment, the accuracy of such tests for predicting the effects of anthropogenic activities on complex ecosystems is questionable. The use of indigenous communities of microorganisms to assess the hazard of toxicants in aquatic ecosystems has many advantages. Theoretical and practical aspects of microbial community tests are discussed, particularly in related to widely cited problems in the use of multispecies test systems for predicting hazard. Further standardization of testing protocols using microbial colonization dynamics is advocated on the basis of previous studies, which have shown these parameters to be useful in assessing risk and impact of hazardous substances in aquatic ecosystems.