Soybean(Glycine max)rhizosphere organic phosphorus recycling relies on acid phosphatase activity and specific phosphorusmineralizing-related bacteria in phosphate deficient acidic soils

Bacteria play critical roles in regulating soil phosphorus(P) cycling. The effects of interactions between crops and soil P-availability on bacterial communities and the feedback regulation of soil P cycling by the bacterial community modifications are poorly understood. Here, six soybean(Glycine max) genotypes with differences in P efficiency were cultivated in acidic soils with long-term sufficient or deficient P-fertilizer treatments. The acid phosphatase(AcP) activities, organic-P concentrations and associated bacterial community compositions were determined in bulk and rhizosphere soils. The results showed that both soybean plant P content and the soil AcP activity were negatively correlated with soil organic-P concentration in P-deficient acidic soils. Soil P-availability affected the ɑ-diversity of bacteria in both bulk and rhizosphere soils. However, soybean had a stronger effect on the bacterial community composition, as reflected by the similar biomarker bacteria in the rhizosphere soils in both P-treatments. The relative abundance of biomarker bacteria Proteobacteria was strongly correlated with soil organic-P concentration and AcP activity in low-P treatments. Further high-throughput sequencing of the phoC gene revealed an obvious shift in Proteobacteria groups between bulk soils and rhizosphere soils, which was emphasized by the higher relative abundances of Cupriavidus and Klebsiella, and lower relative abundance of Xanthomonas in rhizosphere soils. Among them, Cupriavidus was the dominant phoC bacterial genus, and it was negatively correlated with the soil organic-P concentration. These findings suggest that soybean growth relies on organic-P mineralization in P-deficient acidic soils, which might be partially achieved by recruiting specific phoCharboring bacteria, such as Cupriavidus.

Assessing bacterial communities in the rhizosphere of 8-year-old genetically modified poplar(Populus spp.)

Microbe communities in rhizosphere ecosystems are important for plant health but there is limited knowledge of them in the rhizospheres of genetically modified（GM） plants, especial for tree species. We used the amplitude sequencing method to analyze the V4 regions of the 16 S r RNA gene to identify changes in bacterial diversity and community structure in two GM lines（D520 and D521）, one non-genetically modified（nonGM） line and in uncultivated soil. After chimera filtering,468.133 sequences in the domain Bacteria remained. There were ten dominant taxonomic groups（with [1 % of all sequences） across the samples. 241 of 551 genera（representing a ratio of 97.33 %） were common to all samples.A Venn diagram showed that 1.926 operational taxonomic units（OTUs） were shared by all samples. We found a specific change, a reduction in Chloroflexi, in the microorganisms in the rhizosphere soil planted with poplars. Taken together, the results showed few statistical differences in the bacterial diversity and community structure between the GM line and non-GM line, this suggests that there was no or very limited impact of this genetic modification on the bacterial communities in the rhizosphere.

Seasonal comparison of bacterial communities in rhizosphere of alpine cushion plants in the Himalayan Hengduan Mountains

Positive associations between alpine cushion plants and other species have been extensively studied.However,almost all studies have focused on the associations between macrofauna.Studies that have investigated positive associations between alpine cushion plants and rhizospheric microbes have been limited to the vegetation growing season.Here,we asked whether the positive effects that alpine cushion plants confer on rhizospheric microbe communities vary with seasons.We assessed seasonal variations in the bacterial diversity and composition in rhizosphere of two alpine cushion plants and surrounding bare ground by employing a high throughput sequencing method targeting the V3 region of bacterial 16 S rRNA genes.Soil properties of the rhizosphere and the bare ground were also examined.We found that cushion rhizospheres harbored significantly more C,N,S,ammonia nitrogen,and soil moisture than the bare ground.Soil properties in cushion rhizospheres were not notably different,except for soil pH.Bacterial diversities within the same microhabitats did not vary significantly with seasons.We concluded that alpine cushion plants had positive effects on the rhizospheric bacterial communities,even though the strength of the effect varied in different cushion species.Cushion species and the soil sulfur content were probably the major factors driving the spatial distribution and structure of soil bacterial communities in the alpine communities dominated by cushion plants.

Partial function prediction of sulfate-reducing bacterial community from the rhizospheres of two typical coastal wetland plants in China

Sulfate-reducing bacteria(SRB)are ubiquitous anaerobic microorganisms that play signifi cant roles in the global biogeochemical cycle.Coastal wetlands,one of the major habitats of SRB,exhibit high sulfate-reducing activity and thus play signifi cant roles in organic carbon remineralization,benthic geochemical action,and plant-microbe interactions.Recent studies have provided credible evidence that the functional rather than the taxonomic composition of microbes responds more closely to environmental factors.Therefore,in this study,functional gene prediction based on PacBio single molecular real-time sequencing of 16S rDNA was applied to determine the sulfate-reducing and organic substrate-decomposing activities of SRB in the rhizospheres of two typical coastal wetland plants in North and South China:Zostera japonica and Scirpus mariqueter.To this end,some physicochemical characteristics of the sediments as well as the phylogenetic structure,community composition,diversity,and proportions of several functional genes of the SRB in the two plant rhizospheres were analyzed.The Z.japonic a meadow had a higher dissimilatory sulfate reduction capability than the S.mariqueter-comprising saltmarsh,owing to its larger proportion of SRB in the microbial community,larger proportions of functional genes involved in dissimilatory sulfate reduction,and the stronger ability of the SRB to degrade organic substrates completely.This study confi rmed the feasibility of applying microbial community function prediction in research on the metabolic features of SRB,which will be helpful for gaining new knowledge of the biogeochemical and ecological roles of these bacteria in coastal wetlands.

Improving dryland maize productivity and water efficiency with heterotrophic ammonia-oxidizing bacteria via nitrification and cytokinin activity

A two-year field experiment conducted under dryland conditions in semi-humid and drought-prone regions of China aimed to assess the effect of ammonia-oxidizing bacterial on maize water use efficiency and yield.A heterotrophic ammonia-oxidizing bacteria(HAOB)strain S2_8_1 was used.Six treatments were applied:(1)no irrigation+HAOB strain(DI),(2)no irrigation+blank culture medium(DM),(3)no irrigation control(DCK),(4)irrigation+HAOB(WI),(5)irrigation+blank culture medium(WM),and(6)irrigation control(WCK).Results revealed that HAOB treatment increased maize growth,yield,and water use efficiency over controls,regardless of whether the year was wet or dry.This improvement was attributed to the accelerated nitrification in the rhizosphere soil due to HAOB inoculation,which subsequently led to increased levels of leaf cytokinins.Overall,these findings suggest that HAOB inoculation holds promise as a strategy to boost water use efficiency and maize productivity in dryland agriculture.

The Preliminary Study on Screening and Application of Phthalic Acid-Degrading Bacteria

Phthalic acid is a main pollutant, which is also an important reason for the continuous cropping effect of tobacco. In order to degrade the phthalic acid accumulated in the environment and relieve the obstacle effect of tobacco continuous cropping caused by the accumulation of phthalic acid in the soil. In this study, phthalate degrading bacteria B3 is screened from continuous cropping tobacco soil. The results of biochemical identification and 16sDNA comparison show that the homology between degrading bacterium B3 and Enterobacter sp. is 99%. At the same time, the growth of Enterobacter hormaechei subsp. B3 and the degradation of phthalic acid under different environmental conditions are studied. The results show that the environment with a temperature of 30˚C, PH of 7, and inoculation amount of not less than 1.2%, which is the optimal growth conditions for Enterobacter sp. B3. In an environment with a concentration of phthalic acid not exceeding 500 mg/L, Enterobacter sp. B3 has a better effect on phthalic acid degradation, and the degradation rate can reach 77% in 7 d. The results of indoor potting experiments on tobacco show that the degradation rate of phthalic acid by Enterobacter B3 in the soil is about 45%, which can reduce the inhibitory effect of phthalic acid on the growth of tobacco seedlings. This study enriches the microbial resources for degrading phthalic acid and provides a theoretical basis for alleviating tobacco continuous cropping obstacles.

Study of Bacterial Diversity of Mangroves Rhizosphere

Microbial diversity has been an important facet of scientific research, since microbes promise a plethora of biomolecules which are otherwise not found in nature. Microbes are subjected to high level of competition for survival in the environment, and hence develop mechanisms of defense. The biomolecules produced by these microbes as part of their defense or survival mechanism, are of importance for human and animal drugs and many other industrial and environmental applications. The marine counterparts of these terrestrial microbes have yet higher potential, since the marine environment has higher biotic and abiotic stresses, leading to new molecule discovery. In the current study, a bacterial diversity study of the culturable bacteria of the mangrove rhizosphere of Avicennia marina has been undertaken, to understand the flora diversity. Mangroves are unique ecosystems which are under a combination of marine and terrestrial influence. Mangroves are seaward, inland and also found in creek areas. This diversity in their habitat, leads them to produce variable root exudates, which support the growth of different types of organisms. This study has revealed that certain species are dominant in these ecosystems irrespective of the biotic and abiotic stresses, whereas certain species appear only at neutral pH. The study will help select organisms for further biomolecule discovery programs, based on their environment of isolation and other growth parameters.

Vermicompost and Cow Dung Admixture Increases Rhizosphere Bacterial Population and Promotes Rapid Physiological Maturity in Maize (Zea mays L.)

Incessant application of chemical fertilizers to the agricultural fields may alter the composition and activities of soil microbiota.Thus,the shift of cultivation practices from chemical to organic is considered to be the need of the hour in order to maintain soil health.A study was conducted in the agricultural fields of the University of Burdwan,India to observe the impact of organic manure on the rhizosphere bacterial community.The experiments were conducted on maize plants,supplemented with the recommended dose of chemical fertilizer and organic manure(vermicompost and cow dung mixture).Corresponding changes in the plant phenological events and soil health in terms of soil physico-chemical factors and rhizosphere bacterial groups up to the level of CFU g-1×105 dry soil was noted.The results showed a significant increase in population of phosphate solubilizing bacteria during 30DAS.However,at 90 DAS,significant increase in the population of phosphate solubilizing bacteria,nitrifying bacteria,asymbiotic nitrogen-fixing bacteria and protein hydrolyzing bacteria was observed in the organically treated plots.The growth of rhizosphere bacteria was attributed to the type of organic manure supplied to the agricultural fields.In addition,a strong correlation was observed between Zn and protein hydrolyzing bacteria.The soil organic carbon and available nitrogen were strongly correlated with nitrifying,fat solubilizing and phosphate solubilizing groups of bacteria.

Rhizosphere Aeration Improves Nitrogen Transformation in Soil, and Nitrogen Absorption and Accumulation in Rice Plants

Two rice cultivars(Xiushui 09 and Chunyou 84)were used to evaluate the effects of various soil oxygen(O2)conditions on soil nitrogen(N)transformation,absorption and accumulation in rice plants.The treatments were continuous flooding(CF),continuous flooding and aeration(CFA),and alternate wetting and drying(AWD).The results showed that the AWD and CFA treatments improved soil N transformation,rice growth,and N absorption and accumulation.Soil NO3–content,nitrification activity and ammonia-oxidising bacteria abundance,leaf area,nitrate reductase activity,and N absorption and accumulation in rice all increased in both cultivars.However,soil microbial biomass carbon and pH did not significantly change during the whole period of rice growth.Correlation analysis revealed a significant positive correlation between the nitrification activity and ammonia-oxidising bacteria abundance,and both of them significantly increased as the total N accumulation in rice increased.Our results indicated that improved soil O2 conditions led to changing soil N cycling and contributed to increases in N absorption and accumulation by rice in paddy fields.

玉米种植改变了引黄灌区盐渍化土壤细菌多样性与功能

为了明确植物修复对盐渍化土壤细菌群落结构及多样性的影响,本文对宁夏引黄灌区盐渍化土壤玉米种植地根际和非根际土壤以及荒地土壤细菌多样性、群落结构及功能、细菌群落与环境因子之间的相关关系等进行研究。结果表明:玉米种植能够增加盐渍化土壤细菌物种数(OTU, Operational Taxonomic Unit)和多样性,各土壤细菌总物种数和特有物种数(OTU)从高到低依次为:非根际土壤>根际土壤>荒地土壤;土壤细菌多样性(即ACE指数、Chao1指数、Simpson指数与Shannon指数)由大到小均依次为:根际土壤>非根际土壤>荒地土壤, 3种土壤细菌多样性之间差异不显著。玉米种植改变了盐渍化土壤细菌群落结构和功能多样性,玉米种植显著提高了变形菌门(Proteobacteria)与放线菌门(Actinobacteria)两种优势菌门的相对丰度;丛毛单胞菌属(Comamonadaceae)、丝状菌属(Hyphomircobiales)和根瘤菌属(Rhizobiaceae)为3种土壤组间差异贡献最大的物种;玉米种植增加了盐渍化土壤中细菌参与新陈代谢功能与遗传信息处理功能物种的相对丰度,且有效磷、全磷、速效氮、全盐和pH是影响二级功能相对丰度的重要因子。玉米种植后其根际和非根际土壤细菌群落在生态位上与荒地之间存在明显分异。种植玉米修复盐渍化土壤能够改变土壤细菌群落结构、功能和多样性,对改善盐渍化土壤微环境,促进盐渍化土壤微生物功能发挥和盐渍化土壤种植结构优化具有重要意义。

香葱伴生番茄对青枯病及根际微生态特征的影响

【目的】为明确香葱伴生对番茄青枯病及根际微生态特征的影响,揭示香葱伴生番茄降低青枯病发病率的机理。【方法】通过田间试验设置番茄单作和香葱伴生番茄2个处理,分别采集单作发病番茄(QK)、单作健康番茄(NBS)和香葱伴生番茄(BS)的根际土壤,应用16S rDNA高通量测序和液相色谱-质谱联用(LC-MS)技术,探究香葱伴生对番茄根际微生态特征的影响。【结果】田间试验结果表明,番茄单作处理和香葱伴生番茄处理的青枯病平均病株率分别为50.48、31.43%,香葱伴生番茄处理对番茄青枯病的防治效果为37.74%。16S rDNA高通量测序结果表明,BS、NBS根际土壤细菌群落相对丰度和多样性均显著高于QK;与QK相比,BS和NBS根际土壤细菌茄科雷尔氏菌属相对丰度显著降低,而芽孢杆菌属相对丰度升高;与NBS相比,BS根际土壤细菌茄科雷尔氏菌属相对丰度降低,芽孢杆菌属相对丰度显著提高。利用LC-MS技术共鉴定出番茄根际土壤代谢物586种,其中正离子模式代谢物320种,负离子模式代谢物266种,并将代谢物的功能注释至新陈代谢、遗传信息加工和环境信息加工等代谢通路;与NBS相比,BS根际土壤代谢物中的缬氨酸、L-天冬酰胺和柠檬酸的含量均显著降低,L-赖氨酸、谷氨酸、D-谷氨酰胺和异亮氨酸的含量也低于NBS,但差异未达到显著水平。【结论】香葱伴生番茄显著降低番茄青枯病田间发病率,改变了番茄根际土壤中细菌群落结构和番茄根际土壤代谢物含量。

核桃根际耐旱促生菌的分离筛选及其促生作用研究

为获得高效促生的核桃根际菌株,研制微生物菌肥,改善土壤肥力,促进植株生长发育,提升核桃品质奠定理论基础。以核桃根际土壤为材料,分离筛选具有固N、溶P、解K、分泌生长素和产胞外多糖能力的菌株,通过16S rDNA测序鉴定菌属。按照功能叠加增效、功能互补的原则,人工构建合成菌群,采用盆栽试验验证菌群对核桃幼苗的促生效果。结果表明,共筛选出9株耐旱促生菌株,其中5株具有溶P能力,溶P量为2.28~61.63μg·mL^(-1),4株具有分泌IAA能力,分泌IAA量为2.32~9.44μg·mL^(-1),4株具有产胞外多糖的能力,产胞外多糖量为37.69~112.84μg·mL^(-1)。经鉴定分别属于节杆菌属、肠杆菌属、剑菌属、中华根瘤菌属、假单胞菌属和鞘氨醇杆菌属。盆栽试验表明,4种菌群均能显著促进核桃幼苗的生长,株高、生物量和净光合速率,与对照相比,分别增加了32.3%~64.2%、37.6%~52.6%和47.4%~68.5%。此外,复合菌群的施用还显著提高了土壤β-葡萄糖苷酶(BG)、β-N-乙酰葡糖胺糖苷酶(NAG)和碱性磷酸酶(AP)活性,增加了速效P、硝态N及铵态N含量(P<0.05),其中以复合菌群T4效果最佳。研究结果可为研制适合干旱半干旱区的微生物肥料提供菌种资源。

基于高通量测序分析拉萨大黄根部内生菌及根际土壤微生物多样性研究

以拉萨大黄根部内生菌和根际土壤微生物为研究对象,采用高通量测序技术对其测序并运用生物信息学和统计学方法进行分析,以探究拉萨大黄根部内生菌及根际土壤微生物多样性。结果表明,经过聚类注释后拉萨大黄根及根际土壤中真菌共有90个OTU(OperationalTaxonomicUnit,OTU),特有OTU分别为452个和635个;根及根际土壤中细菌共有622个OTU,特有OTU分别为982个和5618个。α多样性分析显示,与根部内生细菌相比拉萨大黄根际土壤细菌估计物种数量大,物种丰富度和均匀度高(P<0.05);拉萨大黄根际土壤真菌比根部内生真菌的物种总数更多,但根际土壤真菌和根部内生真菌的群落多样性无明显差异(P>0.05)。基于β多样性分析得到拉萨大黄根部内生菌与根际土壤微生物的菌群结构存在显著差异(P<0.05、q<0.05)。从群落组成来看,在门水平上,真菌群落中拉萨大黄根及根际土壤的优势菌门为子囊菌门(Ascomycota),细菌群落中根部内生细菌相对丰度最高的为拟杆菌门(Bacteroid-ota),相对丰度为75.44%,在根际土壤中优势门为变形菌门(Proteobacteria),相对丰度为44.36%;在属水平上,真菌群落中根部可被分类的相对丰度最高的属为青霉属(Penicillium),相对丰度为21.8%,根际土壤中可分类的相对丰度最高的为截盘多毛孢属(Truncatella),相对丰度为26.16%。细菌群落中根部可被分类出来的相对丰度最高的为JC017,相对丰度为73.44%,根际土壤中可被分类的相对丰度最高的为Ba-cillus_BD,相对丰度为6.7%。

青海野生中国沙棘根际解钾菌的分离、鉴定及其促生能力比较

【目的】从青海野生中国沙棘(Hippophae rhamnoides subsp.sinensis)根际土中筛选出具有解钾能力的菌株,并比较其促生能力,为高原地区高效生物菌肥的研发提供依据。【方法】利用纯化培养方法从中国沙棘根际土中分离解钾菌;通过形态观察、生理生化检测及16S rDNA序列比对鉴定菌株;对解钾菌的解有机磷、解无机磷、解钾、降解纤维素的能力进行测定;将解钾菌接种于空心菜幼苗以验证其促生效果。【结果】K15、K50和K65三株解钾菌均为乙酸钙不动杆菌(Acinetobacter calcoaceticus)。培养3 d后,3株解钾菌溶解有机磷的浑浊圈直径为3.75~7.13 mm,解有机磷菌液中磷的质量浓度为5.12~11.33μg·mL^(-1);溶解无机磷的透明圈直径为3.25~5.31 mm,解无机磷菌液中磷的质量浓度为3.39~6.63μg·mL^(-1);解钾的黄色光圈直径为17.53~25.17 mm,解钾菌液中K^(+)质量浓度为4.87~7.15μg·mL^(-1);降解纤维素的透明圈直径为8.37~12.07 mm。3株解钾菌均可提高空心菜种子的萌芽率(表现为K65>K50>K15)。施用解钾菌菌液可提高空心菜幼苗的生长发育速度(表现为K65>K50>K15)。其中,K65对幼苗的促生作用最显著,K65处理的幼苗鲜质量达到0.24 g,比CK提高33.3%。【结论】3株解钾菌均具有解有机磷、解无机磷、解钾、降解纤维素的能力;施用解钾菌菌液后空心菜幼苗的生长状况均得到一定程度的改善,种子发芽率显著提高,其中,K50和K65的促生效果均比K15好。

微塑料对土壤微生物群落结构影响及共生网络分析

土壤是微塑料的主要储存库,微塑料进入土壤生态系统后可以形成与周围环境显著不同的“塑料圈”,影响土壤微生物群落结构。通过外源添加微塑料颗粒模拟不同程度的农田土壤微塑料污染,探究微塑料对土壤微生物群落的影响。结果显示,微塑料污染会对土壤中微生物属水平细菌和真菌群落带来极大改变,根际土壤和非根际土壤的微塑料处理高浓度组真菌群落特有属数量显著高于低浓度组(p<0.05),且微塑料污染引起的根际土壤与非根际土壤的细菌群落和真菌群落结构变化均存在较大差异。土壤微生物群落多样性及共生网络分析结果表明,高浓度组微塑料添加显著降低土壤微生物多样性,微塑料对根际土壤微生物的影响大于非根际土壤。研究结果提示土壤真菌群落对微塑料污染的响应程度大于细菌群落,未来土壤微塑料相关研究需要进一步重视根际土壤监测。

根际细菌在长刺蒺藜草氮素利用中的作用

【目的】入侵植物长刺蒺藜草在贫瘠土壤中能够快速生长和扩张,形成单一优势群落。本研究分析长刺蒺藜草入侵对土壤氮循环及相关微生物群落的影响,以期为揭示其入侵的微生态学机理提供理论依据。【方法】利用16S rRNA和nifH基因扩增子高通量测序技术分析长刺蒺藜草、披碱草、冰草、狗尾草根际土壤细菌及固氮菌群落结构和功能的差异。【结果】长刺蒺藜草入侵显著增加了土壤全氮和硝态氮含量,显著降低了水溶性氮和铵态氮的含量。根际土壤高通量分析结果表明:芽孢杆菌、蓝细菌、念珠藻、鱼腥藻、厚壁菌门在长刺蒺藜草固氮菌群落中有明显富集;长刺蒺藜草可能通过增加变形菌门的相对丰度,降低蓝细菌和厚壁菌门的相对丰度来提高其固氮能力,促进对氮素的吸收利用;硝化螺旋菌属和阿菲波菌属在长刺蒺藜草对氮素的利用过程中影响较小。【结论】长刺蒺藜草通过改变入侵地根际土壤细菌和固氮菌的群落结构,影响根际土壤的氮素环境,以利于自身生长。

合成菌群对大豆根际和根内微生物群落的影响

为了探究施用合成菌群对大豆生长和根际及根内微生物的影响,利用大豆根际促生菌,通过功能互补和功效叠加原则构建4组合成菌群(SynComs)。根据盆栽试验的促生效果选出最优菌群并取其根际土和根系分别进行宏基因组测序和16S rRNA基因测序,探究合成菌群对大豆根际土壤和根内微生物群落和功能的影响。盆栽试验表明,合成菌群SynCom 4可显著增加大豆株高、地上鲜重、根长、根鲜重和根瘤数。SynCom 4由克雷伯氏菌JP07(Klebsiella JP07)、克雷伯氏菌GD04、假单胞菌LH19(Pseudomonas LH19)、不动杆菌JP32(Acinetobacter JP32)、克雷伯氏菌PKO08、芽孢杆菌JK32(Bacillus JK32)、寡养单胞菌GD03(Stenotrophomonas GD03)和克雷伯氏菌LH13组成。宏基因组测序结果表明,接种SynCom 4提高了细菌微酸菌纲(unclassified_Acidimicrobiia)、藤黄色单胞菌属(Luteimonas)、绿屈挠菌纲(unclassified_c_Chloroflexia)、热厌氧杆状菌目(unclassified_o_Thermoanaerobacteroles)等的相对丰度,增加了参与氮代谢、磷转化、吲哚乙酸和赤霉素生物合成等功能基因的相对丰度。16S rRNA基因测序结果表明,SynCom 4增加了大豆根内细菌群落多样性,提高了黄单胞菌科(unclassified_f_Xanthomonadaceace)、食氢产水菌属(Hydrogenophaga)、根瘤菌目(unclassified_o_Rhizobiales)、黄杆菌科(norank_f_Xanthobacteraceae)等的相对丰度。PICRUSt2功能预测表明,SynCom 4增强了与氨基酸、维生素、脂质和次级代谢产物合成有关的功能。综上,宏基因组测序和16S rRNA基因测序结果表明,SynCom 4显著改变了根际和根内微生物群落的结构和组成,提高了微生物的多样性,增加了菌属和功能基因的相对丰度。施用SynCom 4有效促进了大豆生长,改变了根际和根内的细菌微生物群落结构和功能。

铜镍复合胁迫对鹰嘴紫云英根际土壤细菌群落的影响

重金属长期存在于土壤中,会对土壤微生物的生长、代谢产生影响,从而引起微生物群落结构的变化。为探究不同程度重金属污染对土壤细菌群落组成的影响,本研究以金川区农田铜镍污染土壤(Cu^(2+)、Ni^(2+)含量分别为261.1 mg/kg、258.2 mg/kg,pH为8.3)为研究对象,以耐铜镍植物卢塔纳鹰嘴紫云英(Astragalus cicer cv.Lutana)为供试材料,在温室采用盆栽试验法,研究铜、镍不同浓度复合溶液(0、100、200、400、800、1600 mg/kg)处理对根际土壤理化性质、生物学特性及根际细菌群落结构分布情况的影响。结果表明,随铜镍复合胁迫浓度的升高,根际土壤水分含量、Cu^(2+)和Ni^(2+)含量均升高;速效氮、磷、钾含量、微生物量碳、氮、磷含量、有机质含量及Chao 1指数、Pielou指数、Shannon指数和Simpson指数均先升后降,其中除速效钾外,其余指标均在铜镍胁迫浓度为100 mg/kg时达到最高;根际土壤pH值、脲酶、过氧化氢酶、脱氢酶和碱性磷酸酶活性均下降;优势菌门主要有变形菌门、酸杆菌门、放线菌门、拟杆菌门和芽单胞菌门;除变形菌门以外,随铜镍胁迫浓度升高,芽单胞菌门和拟杆菌门的相对丰度呈显著上升,而酸杆菌门的相对丰度先增后降,放线菌门的相对丰度显著下降。冗余分析和蒙特卡洛置换检验结果显示,脱氢酶、pH和微生物量氮是根际土壤细菌群落结构变化的主导因子。在铜镍胁迫浓度为100 mg/kg时可提高根际细菌群落多样性,在100 mg/kg以上会抑制根际细菌群落多样性。