植物根际促生菌促生特性研究进展

根际微生物组是决定农作物健康状况的关键因素之一,也是调节农作物与生物和非生物环境相互作用的重要因素。植物根际促生菌(plant growth-promoting rhizobacteria, PGPR)为农作物宿主提供了多种有益作用,通过化学交流以复杂的方式与农作物、土壤相互作用,进而促进农作物生长。本文综述了PGPR对农作物的促生机制、PGPR与农作物的互作及其在农业实践中的应用,并展望了PGPR在农业实践中应用的发展趋势,以期为今后PGPR的应用和研究提供新的思路和理论支撑。     

植物根际促生菌及丛枝菌根真菌协助植物修复重金属污染土壤的机制

植物修复是一种前景广阔的重金属污染土壤的主要修复技术,在微生物的协助下效果更为显著。植物根际促生菌可通过分泌吲哚-3-乙酸(IAA)、产铁载体、固氮溶磷等方式促进植物生长、改善植物重金属耐受性,从而有效提高重金属污染土壤的植物修复效率。菌根真菌是土壤-植物系统中重要的功能菌群之一,可侵染植物根系改变根系形态和矿质营养状况,通过菌丝体吸附重金属,也可产生球囊霉素、有机酸、植物生长素等次生代谢产物改变重金属生物有效性。植物根际促生菌与丛枝菌根真菌可对植物产生协同促生作用,在重金属污染土壤修复中具有一定应用潜力。目前,国内外关于植物根际促生菌和丛枝菌根真菌互作已有大量研究,而二者的相互作用机理仍处于探索阶段。本文综述了近年来国内外植物根际促生菌和丛枝菌根真菌在重金属污染土壤植物修复中的作用机制,并对其研究前景进行展望。     

胡杨根际细菌提高木本植物对重金属胁迫的耐受性

胡杨是我国西北荒漠地区特有的、对多种非生物逆境具有高抗逆性的树种,但其相关微生物的生态和生理功能研究还比较缺乏.本文从新疆沙雅地区原始胡杨林根际土壤中分离出重金属抗性细菌共72株.其中具有单一重金属(Cu²⁺、Ni²⁺、Pb²⁺或Zn²⁺)抗性的细菌菌株50株,有三重以上重金属抗性的菌株9株.将其中5株多重重金属抗性细菌接种至生根的竹柳插条,进行重金属胁迫下的盆栽培养.结果表明: 在铜或锌胁迫下,5株多重重金属抗性细菌对竹柳的生长抑制有不同程度的缓解,其中假单胞菌Z30和贪铜菌N8菌对铜和锌两种胁迫下竹柳生物量的增长与不接菌对照相比均达到显著差异水平.说明在非重金属污染区生长的胡杨根际存在多样性的重金属抗性细菌,其中一些多重重金属抗性菌对改善重金属胁迫下植物的生长有显著作用,具有应用于木本植物-微生物联合修复环境重金属污染的价值.     

植物根际促生菌的筛选及其对玉米的促生效应

[目的]以不同植物根及根际土壤为研究材料,进行植物根际促生菌(PGPR)的筛选,并探索其植物促生作用机制.[方法]以解磷、固氮、产氨、产IAA和拮抗3种常见病原真菌为筛选标准,测定了初筛菌株的多项促生能力,并通过对这些菌分别单独回接和多菌混接的玉米盆栽试验,测定了其对玉米的促生效应.[结果]从渭南、成阳、安康、商洛和榆林5地分离得到的158株菌中有17株茵具有上述多种植物促生作用的菌株.盆栽试验的测定结果表明:单独接种和多菌混合接种在玉米株高、根长、茎长、茎平均直径和干重方面与对照组相比较都有所增加,尤其是在多个指标上,多菌混合接种所显示出的促生效应均明显优于单菌接种.[结论]所筛选到的具有多种促生能力的菌株,可以为进一步构建植物根际促生菌(PGPR)菌群提供良好的种质资源.     

植物根际促生菌的筛选及鉴定

【目的】植物根际促生菌(PGPR)和植物的互作关系往往不稳定,PGPR菌群有可能提高菌株对野外环境的适应性。为此,本文根据PGPR促生机制的多样性,从不同植物根际土壤进行了PGPR的筛选及鉴定。【方法】首先,按照固氮、解磷、解钾、拮抗6种常见病原真菌,同时能在植物根际定殖为基本初筛标准,然后在实验室条件下测定初筛菌株的多项促生能力(PGP),最后通过生理生化试验和16SrRNA基因序列分析对所筛菌株进行鉴定。【结果】从江苏扬州、盐城等地土壤样品筛选出14株PGPR,具有体外抑菌、产NH3、产IAA、产HCN、产嗜铁素、解磷、溶钾、固氮以及产抗生素等促生能力。分类鉴定结果显示:7株属于假单胞菌属(Pseudomonas)、3株属于类芽孢杆菌属(Paenibacillus)、2株为芽孢杆菌属(Bacillus)、1株为布克霍尔德氏菌属(Burkholderia)、1株为欧文氏菌属(Erwinia)。【结论】所筛细菌具有多种促生能力,且能在根际定殖,为进一步构建多功能PGPR广适菌群提供菌株资源。     

一株具有植物促生作用的重金属铅吸附菌的筛选与鉴定

【背景】随着工业化的发展,重金属污染逐渐成为主要的环境污染之一。微生物修复去除重金属污染成为近些年来新兴的修复方法,筛选开发具有良好修复功能的微生物菌株具有重要的现实意义。【目的】筛选具有促进植物生长作用的重金属修复菌株,为生物修复和植物促生等综合开发利用提供微生物资源。【方法】利用选择性培养基从淤泥中筛选重金属铅的抗性菌株,根据形态学观察、生理生化鉴定和16S rRNA基因序列分析对菌株进行分离鉴定,通过单因素分析不同培养条件对菌株生长的影响;采用原子吸收光谱法、比色法及平板对峙法等对菌株的重金属铅吸附率、无机磷溶解能力、吲哚乙酸(indole-3-acetic acid,IAA)分泌及拮抗镰刀菌效果等进行分析。【结果】从污染严重的塘泥中筛选到一株对重金属铅有较好吸附率的菌株,在150 mg/L Pb²⁺浓度下,对Pb²⁺的吸附率达90%以上;初步鉴定该菌株为蜡样芽孢杆菌,命名为SEM-15;菌株还具有较好的溶解无机磷、分泌IAA及拮抗镰刀菌的能力;菌株生长适应性强,可以在pH 10.0的强碱性环境下生长,该菌株具有很好的重金属铅污染修复及促生防病的应用潜力。【结论】菌株SEM-15是一株具有植物促生作用的重金属铅吸附菌株,在重金属污染土壤联合植物修复的应用中可能具有较好的开发价值。     

强化龙葵富集镉根际促生菌的分离、筛选与鉴定

【背景】植物-微生物联合修复土壤重金属污染日渐兴起,获取与超富集植物高效互作的微生物是实现联合修复技术进步的关键。龙葵在镉农田污染修复中广泛应用。【目的】筛选可促进龙葵生长及富集镉的耐镉根际促生菌。【方法】从龙葵根际土分离耐镉菌株,筛选具有良好促生特性的菌株,水培试验考察镉胁迫下菌株对植物生长及镉富集能力的影响,确定可促进龙葵生长及富集镉的微生物菌株,通过生理生化特性和16S rRNA基因序列分析进行菌株的初步鉴定。【结果】分离得到NT1、AXY1、AW2和AW1四株强化龙葵富集镉促生菌,经鉴定分别为Lysinibacillus sp.、Beijerinckia fluminensis、Achromobacter animicus和Herbaspirillum huttiense。上述菌株均可有效促进龙葵生长,增加其株高和干物质积累,提高地上部镉富集量。其中,NT1可使株高、地上部干重分别增加31.33%和62.65%,AW2可使地上部镉富集量增加37.29%。【结论】筛选所得菌株可为提高植物修复效率提供实践依据,为研制田间施用生态功能菌剂做铺垫,用于农田镉污染的微生物-龙葵联合原位修复。     

田菁根际促生菌的筛选及其促生耐盐效果

【目的】为探究盐生植物田菁及其根际功能微生物改良盐碱地的效果,本研究从黄河三角洲盐碱区田菁根际土壤中分离促生菌,并明确其耐盐促生效果。【方法】采用选择培养方法从田菁根际土壤中分离固氮菌、解磷菌以及解钾菌,并进行16S rRNA分子生物学鉴定。之后对菌株的耐盐及促生特性进行测定,筛选性状优良菌株进行玉米促生作用研究。【结果】共分离得到105株根际促生菌,其中N102兼具多种促生特性且耐盐性达15%。田菁种子发芽试验表明,N102可显著提高田菁发芽率(47%,P<0.05)、芽长(48.5%,P<0.05)和根长(60%,P<0.05);玉米盆栽试验结果表明,N102对盐胁迫下玉米的株高、根长、叶绿素含量、地上部干重以及根干重具有显著的促进作用。经系统发育分析,N102与Enterobacter soli ATCC BAA-2102 (NR117547)序列相似度为99.30%,鉴定属于Enterobacter属。【结论】菌株N102具有多种植物促生耐盐特性,具有开发成有效促进盐碱地作物生长的微生物肥的良好前景。     

多功能植物根际促生菌对东北黑土区玉米的促生效果

应用微生物肥料改良土壤是提高土壤及化肥养分利用率的重要途径之一,但微生物肥料的效果受作物及生态条件的影响较大,目前适合东北地区玉米生产的微生物肥料应用研究较少。本研究针对我国东北黑土类型及气候特点,从当地玉米根际土中筛选分离出5株具有不同程度的合成生长素(IAA)、溶磷、解钾、产铁载体等多功能的植物根际促生菌MZ1、MZ2、MZ3、MZ4和MZ5;生态适应性研究发现5株菌均有不同程度的耐盐、耐干旱、耐酸碱以及耐农药等特性;16S rRNA基因序列分析鉴定出它们分别属于鞘氨醇单胞菌、肠杆菌、假单胞菌、芽孢杆菌和根瘤菌;玉米田间试验结果显示,在减施50%氮肥的条件下, 与不接种对照相比,接种MZ1、MZ3和MZ5可增产19.9%~25.0%。因此,MZ1、MZ3和MZ5具有发展为适合东北地区土壤和气候环境的玉米微生物肥料的潜力。     

耐砷促生菌对超富集植物蜈蚣草砷吸收及根际微生物群落的调控作用

【目的】分析添加外源促植物生长微生物(plant growth-promoting bacteria,PGPB)对植物生长、砷富集和根际微生物的影响,为植物-微生物联合修复砷污染土壤提供参考。【方法】通过添加外源PGPB,研究蜈蚣草生物量和砷富集量与外源微生物促植物生长特性的关系,采用高通量测序技术分析蜈蚣草根际微生物群落在外源PGPB干预下的变化规律。【结果】2株根际菌(假单胞菌PG12、芽孢杆菌R19)和1株内生菌(恶臭假单胞菌S6)具备典型的促植物生长特性,对蜈蚣草的促生作用顺序为：PG12>S6>R19,与对照组相比,生物量分别提高了234%(P<0.01)、136%(P<0.01)和67%;添加外源PGPB后,蜈蚣草砷含量从对照的18.50 mg提高到了31.25-46.95 mg,增幅高达153%(PG12)和139%(S6),对应的蜈蚣草砷浓度从2616.34mg/kg降至1348.04-2 156.23 mg/kg,呈现出典型的砷“稀释效应”;α多样性指数Sobs、Chao和Ace显示,仅R19处理显著提高了根际微生物的群落多样性,而β多样性指数...     

植物修复——治理土壤重金属污染的新途径

介绍了重金属污染土壤的植物修复的概念、原理与研究动态以及重金属超积累植物的特性 ,及其在治理污染土壤中的潜力 ,为土壤重金属污染的整治及其生态的修复提出新途径。     

Screening of plant growth promoting traits in heavy metals resistant bacteria: Prospects in phytoremediation

Phytoremediation is considered as a novel environmental friendly technology, which uses plants to remove or immobilize heavy metals. The use of metal-resistant plant growth-promoting bacteria (PGPB) constitutes an important technology for enhancing biomass production as well as tolerance of the plants to heavy metals. In this study, we isolated twenty seven (NF1-NF27) chromium resistant bacteria. The bacteria were tested for heavy metals (Cr, Zn, Cu, Ni, Pb and Co) resistance, Cr(VI) reduction and PGPB characters (phosphate solubilization, production of IAA and siderophores). The results showed that the bacterial isolates resist to heavy metals and reduce Cr(VI), with varying capabilities. 37.14% of the isolates have the capacity of solubilizing phosphate, 28.57% are able to produce siderophores and all isolates have the ability to produce IAA. Isolate NF2 that showed high heavy metal resistance and plant growth promotion characteristics was identified by 16S rDNA sequence analysis as a strain of Cellulosimicrobium sp.. Pot culture experiments conducted under greenhouse conditions showed that this strain was able to promote plant growth of alfalfa in control and in heavy metals (Cr, Zn and Cu) spiked soils and increased metal uptake by the plants. Thus, the potential of Cellulosimicrobium sp. for both bioremediation and plant growth promotion has significance in the management of environmental pollution.     

趋磁细菌培养及用于吸附分离贵重金属离子

生物吸附是有效处理含较低浓度重金属离子废水的廉价方法之一。本文通过对污水处理厂活性污泥的富集和培养, 经过分离、纯化活性污泥中的细菌, 最终得到了趋磁细菌MTB-11s。通过16S rDNA鉴定, 菌株MTB-11s属于代尔夫特菌属。对趋磁细菌的生物吸附性能进行了研究, 实验结果表明, 趋磁细菌MTB-11s对不同金属离子具有选择吸附特性, 其对银离子的吸附表现为快速过程, 温度对其吸附性能的影响较小, pH值为4?8时吸附率较高; 随着干菌浓度的增加, 吸附率不断升高, 最终趋于平稳; 随着银离子初始浓度的增加, 吸附率呈现先升高后降低的趋势。在菌量充足或金属离子浓度较低时, 铜、钴离子的存在能促进银离子的吸附, 其他范围则表现为竞争吸附。     

Research Advances on the Mechanisms of Heavy Metal Tolerance in Plants

Heavy metals impact on the cytoplasmic function in a number of different ways, principally by their binding to protein sulflhdryl groups, by producing a deficiency of essential ions and, eventually, by substituting the essemial ions. Other modes of toxicity are possible, including disruption of cell transport processes and oxidative damage by free radicals generated by metal redox cycling. Plants have developed a variety of biochemical defense strategies to prevent heavy metal poisoning. The possible defense mechanism in plant may involve: metal binding to cell walls, avoidance of uptake these toxic metal ions, reduction of heavy metal transport across the cell membrane, active efflux, compartmentalization and metal chelation. Phytochelatins that can tightly bind and sequester metals may play an important role in the accumulation of heavy metals and preventing them from entering the cell metabolic pathway, the rates of high molecular weight (HMW) metal phytochelatin complexes (Cd-Sa-complex) formation may be an important determinant of the plant tolerance. In addition, plants possess several antioxidant defense systems to protect themselves from the oxidative stress by heavy metals.     

The use of transgenic canola (Brassica napus) and plant growth-promoting bacteria to enhance plant biomass at a nickel-contaminated field site

The applicability of transgenic plants and plant growth-promoting bacteria to improve plant biomass accumulation as a phytoremediation strategy at a nickel (Ni)-contaminated field site was examined. Two crops of 4-day old non-transformed and transgenic canola (Brassica napus) seedlings in the presence and absence of Pseudomonas putida strain UW4 (crop #1) or P. putida strain HS-2 (crop #1 and 2) were transplanted at a Ni-contaminated field site in 2005. Overall, transgenic canola had increased growth but decreased shoot Ni concentrations compared to non-transformed canola, resulting in similar total Ni per plant. Under optimal growth conditions (crop #2), the addition of P. putida HS-2 significantly enhanced growth for non-transformed canola. Canola with P. putida HS-2 had trends of higher total Ni per plant than canola without P. putida HS-2, indicating the potential usefulness of this bacterium in phytoremediation strategies. Modifications to the planting methods may be required to increase plant Ni uptake.     

植物对重金属的吸收和分布

植物修复是利用植物来清除污染土壤中重金属的一项技术。该技术成功与否取决于植物从土壤中吸取金属以及向地上部运输金属的能力。植物对金属的吸收主要取决于自由态离子活度。许多螯合剂能诱导植物对重金属的吸收。金属离子在液泡中的区域化分布是植物耐重金属的主要原因。同时,细胞内的金属硫蛋白、植物螯合脓等蛋白质以及有机酸、氨基酸等在金属贮存和解毒方面也起重要作用。本文还论述了重金属在植物体内运输的生理及分子方面的研究进展。     

红树植物抗重金属污染研究进展

综述了重金属污染对红树植物生长的影响,红树植物吸收重金属并在其体内分布以及在这种污染环境下红树植物可能存在的抗性机制。红树植物是通过根部吸收重金属的,进入其体内的重金属除少量分布在叶表面的各种腺体组织中外,主要富集在根部;对吸收到体内的重金属红树植物通过细胞壁沉淀,液泡的区域化等有效方式以降低其毒性;红树植物还可通过渗透作用把重金属排除到体外以减少对自身的毒害;另外,生长在此环境下的红树植物以增强自身抗氧化系统来加强其抗重金属的能力。对今后有关这方面的研究趋势提出了一些看法。     

Promotion of Plant Growth by Bacterial ACC Deaminase

To date, there has been only limited commercial use of plant growth-promoting bacteria in agriculture, horticulture, and silviculture. However, with recent progress toward understanding the mechanisms that these organisms utilize to facilitate plant growth, the use of plant growth-promoting bacteria is expected to continue to increase worldwide. One of the key mechanisms employed by plant growth-promoting bacteria to facilitate plant growth is the lowering of plant ethylene levels by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. This article reviews the published work on this enzyme, with an emphasis on its biochemistry, protein structure, genes, and regulation. In addition, this article provides some initial insights into the changes in both plants and ACC deaminase-containing plant growth-promoting bacteria as a consequence of plant-microbe interactions. Finally, a brief discussion of how bacterial ACC deaminase and indoleacetic acid (IAA) together modulate plant growth and development is included.     

Biological activity and colonization pattern of the bioluminescence-labeled plant growth-promoting bacterium Kluyvera ascorbata SUD165/26

Kluyvera ascorbata SUD165/26 is a spontaneous siderophore-overproducing mutant of K. ascorbata SUD165, which was previously isolated from nickel-contaminated soil and shown to significantly enhance plant growth in soil contaminated with high levels of heavy metals. To develop a better understanding of the functioning of K. ascorbata SUD165/26 in the environment, and to trace its distribution in the rhizosphere, isolates of this bacterium were labeled with either green fluorescent protein or luciferase. When the plant growth-promoting activities of the labeled strains were assayed and compared with the activities of the unlabeled strain, none of the monitored parameters had changed to any significant extent. When the spatial colonization patterns of the labeled bacteria on canola roots were determined after seed application, it was observed that the bacterium was tightly attached to the surface of both roots and seeds, and formed aggregates. The majority of the bacterial population inhabited the upper two thirds of the roots, with no bacteria detected around the root tips.