黄土高原天然和人工油松林根际土壤解磷细菌群落特征及其功能

为了揭示油松-根系微生物的互作关系及其对油松林分稳定性的影响,本研究选择陕西省黄龙县天然和人工油松林,采集油松根际与非根际土壤,测定非根际土壤化学特性,分离纯化根际土壤解磷(有机磷和无机磷)细菌,通过DNA基因测序鉴定解磷细菌,并测定解磷细菌的解磷能力。结果表明: 天然油松林非根际土壤中全碳(TC)、全氮(TN)含量以及C/N、N/P极显著高于人工油松林。2种油松根际土壤中共鉴定出20属65种解磷细菌,其中以芽孢杆菌属、链霉菌属和假单胞菌属为优势菌群;天然油松林根际解磷细菌多样性、丰富度和均匀度指数均高于人工油松林,而优势度指数低于人工油松林。链霉菌属与非根际土壤TC、TN和C/N、N/P呈正相关,而芽孢杆菌属和假单胞菌属与非根际土壤硝态氮、铵态氮、有效磷及全磷含量呈正相关。2种油松林根际土壤不同解磷细菌的解磷能力存在差异,其中天然和人工油松林根际共有的解磷细菌为假单胞菌Pseudomonas sp.34-5,其对磷酸钙的解磷能力最高,为11.40 μg·mL^-1;天然油松林根际独有的解磷细菌蕈状芽胞杆菌BF1-5对卵磷脂的解磷能力最高,为4.58 μg·mL^-1。该林区2种油松林根际解磷细菌菌群结构存在显著差异。与人工油松林相比,天然油松林根际土壤解磷细菌群落多样性更丰富且分布更均匀,解磷能力普遍高于人工林。     

本溪山樱根际与非根际解磷细菌群落结构及动态变化

利用选择性培养基,对不同基质中的本溪山樱(Cerasus sachalinensis) 根际与非根际解磷细菌进行了分离、鉴定和分类,分析了3种不同基质中根际与非根际解磷细菌数量和类群的变化.结果表明,从3种不同配比的基质中分离纯化获得的解磷细菌分别属于13个属,以芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)和沙雷铁氏菌属(Serratia)为主.其中添加炉渣的基质最适于解磷细菌的生长与繁殖,其种群数量最高,但类群的多样性指数低于另外两种土壤.本溪山樱不同生育期根际与非根际解磷细菌种群数量不同,新梢停长期根际中定殖的解磷细菌种群最多（共分离到6个菌属）,新梢迅速生长期和落叶期较少,萌芽期最少.根际土壤解磷细菌多样性亦随生育期发生变化,新梢迅速生长期最高,落叶期次之,新梢停长期最低.非根际土壤则有随生育期逐渐减小的趋势.解磷细菌的根际效应较明显     

少花蒺藜草入侵对根际土壤磷细菌群落多样性的影响

[目的]入侵植物少花蒺藜草在磷元素受限的贫瘠沙质土壤中能够快速生长和种群扩张,形成单一优势群落。本文解析了少花蒺藜草在磷胁迫条件下对磷素的高效利用机制,以期为揭示其入侵机理提供理论依据。[方法]设置少花蒺藜草、冰草、狗尾草和空白对照4个处理,通过高通量测序技术,从土壤解磷微生物的角度分析各处理间土壤中解磷细菌的组成差异。[结果]少花蒺藜草入侵显著提高了土壤磷酸酶的活性和土壤解磷菌的群落多样性。PCA与UPGMA聚类结果表明,少花蒺藜草与狗尾草根际磷细菌物种组成相似性最大。LEfSe多级物种差异判别分析结果表明,少花蒺藜草根际显著富集且与其他处理有显著性差异的解磷菌类群为α-变形菌、链霉菌,其在少花蒺藜草对磷的吸收中可能起较为重要的作用。变形菌门、浮霉菌门和放线菌门与少花蒺藜草根际土壤中的全磷含量呈显著正相关,放线菌门与少花蒺藜草根际土速效磷含量有紧密联系。[结论]少花蒺藜草通过改变入侵地根际土壤的解磷菌群落结构间接影响根际土壤的磷素环境,从而利于自身生长。     

杨树人工林连作与轮作对土壤解磷微生物类群的影响

采用宏基因组测序技术,研究了杨树人工林Ⅰ代林地和连作Ⅱ代林地根际土和非根际土、Ⅱ代林地主伐后轮作花生地和轮荒地土壤中解磷微生物类群特征及磷酸酶基因丰度变化.结果表明: 参与磷循环微生物共9属,芽孢杆菌属和假单胞菌属为优势菌群.土壤解磷微生物丰度大小顺序为轮荒地>轮作花生地>Ⅱ代林地>Ⅰ代林地;主伐更新后轮作花生地和轮荒地芽孢杆菌属和假单胞菌属丰度显著升高,节杆菌属、慢生根瘤菌属、链霉菌属丰度显著降低;但在人工林根际土壤中,与Ⅰ代林根际相比,Ⅱ代林根际土壤与此规律相反.在根际与非根际土壤中,芽孢杆菌属和假单胞菌属丰度为根际小于非根际,节杆菌属、慢生根瘤菌属、链霉菌属丰度为根际大于非根际.磷酸酶基因总丰度为Ⅰ代林地>轮荒地>Ⅱ代林地>轮作花生地,且在Ⅰ、Ⅱ代林中根际效应明显,但Ⅱ代林根际与非根际差异缩小且部分磷酸酶基因的根际丰度低于非根际丰度.解磷微生物数量与酚酸含量呈显著负相关,与pH值呈正相关.     

菌丝室接种解磷细菌Bacillus megaterium C4对土壤有机磷矿化和植物吸收的影响

通过30μm尼龙网将根盒分成根室和菌丝室,菌丝室中的低磷土壤施加75 mg P/kg土壤的植酸钙,研究了菌丝室土壤中丛枝菌根(AM)真菌Glomus intraradices和解磷细菌Bacillus megaterium C4对有机磷的矿化和吸收.结果表明,在试验条件下,植酸钙的溶解性很低,对土壤溶液有机磷的贡献不大.接种解磷细菌C4提高了土壤中磷酸酶的活性,减少了土壤中有机磷的含量.但是,由于存在解磷细菌与AM真菌对磷的竞争,解磷细菌矿化出的磷大部分被自身利用,AM真菌的生长受到抑制,解磷细菌对植物磷营养的改善没有表现出显著的贡献.     

接种AM菌对西部黄土区采煤沉陷地柠条生长和土壤的修复效应

以采煤沉陷区柠条为宿主植物,研究接种丛枝菌根真菌(arbuscular mycorrhizal fungi,简称AM菌)对柠条生长和根际土壤的改良效应。结果表明:8月份接种AM菌比不接菌柠条的株高、冠幅和地径显著增加了29.11%,29.83%和14.81%,9月份接菌区柠条的根长、平均直径、根表面积和根体积分别比对照区增加了151.0%,34.2%,116.0%和129.3%。接种AM菌增强柠条的抗逆性,接菌区的柠条叶片可溶性糖含量和过氧化氢酶活性分别比对照区增加了13.4%和111.1%。8月份接种AM菌改善了土壤的生物理化性质,接菌区有机质、碱解氮、速效磷和速效钾比对照区分别增加7.06g/kg,140.0 mg/kg,1.82 mg/kg和16.72mg/kg,接种AM菌显著增加了根际土壤中真菌、放线菌、细菌数量和酸性磷酸酶活性。总之,接种AM菌促进采煤沉陷区柠条的生长和土壤的改良。     

纤维素分解菌与无机磷细菌的相互作用

大多数土壤全磷含量较高 ,但由于其固定能力很强 ,不仅有效磷含量较低 ,而且施入的水溶性磷肥很快转化为无效形态。活化土壤中无效磷库 ,提高其有效性 ,是一个具有重要实践意义的研究课题。研究结果表明 ,土壤中存在许多具活化无效磷功能的微生物 ,尤其在根际土壤中解磷微生物的数量比非根际要多[8] ,这些微生物统称为解磷菌。增加土壤或根际解磷菌的数量 ,就能活化土壤中的无效磷 ,提高磷的利用率。但土壤中的解磷菌大多数是腐生性的 ,其生长繁殖需要碳源 ,而多数情况下 ,土壤碳源很少 ,且主要是农作物残体 ,其主要成分是纤维素和半纤维素 …     

生姜根系不同生态位细菌群落多样性特征、组成及结构差异

生姜作为常见的调味品和传统中药材,是我国重要的经济作物之一。作为取食部分的生姜块茎与根系直接相连,其产量、品质与根相关细菌群落密切相关。然而,关于生姜根系微环境中细菌群落的特点仍鲜有报道,土壤环境能否衍生出宿主特异性内生菌群落尚不清楚。以生姜根系不同生态位细菌群落为研究对象,采用高通量测序技术,对非根际、根际及根内细菌进行16S rRNA基因测序。结果表明,不同生态位细菌群落多样性存在显著差异,其中非根际及根际细菌群落多样性(Shannon index, Observed species, Faith′s PD)显著高于内生菌群落。同时,各生态位共现网络稳定性和复杂度表现为非根际>根际>根内细菌群落。而在组成上,细菌群落在不同生态位差异显著(R²=0.57,P=0.001)。其中变形菌门(Proteobacteria)是根内的优势门,该门类下假单胞菌属(Pseudomonas)、短波单胞菌属(Brevundimonas)、寡养单胞菌属(Stenotrophomonas)及泛菌属(Pantoea)在根内显著富集。在根际细菌中,拟杆菌门(Bacteroid...     

杨树根际解无机磷细菌Mp1-Ha4的鉴定及其解磷机理

解无机磷细菌能够溶解土壤中的难溶性磷酸盐,增加土壤有效磷含量,促进植物生长。以一株杨树根际土壤中筛选得到的解无机磷细菌Mp1-Ha4为研究对象,利用分子生物学的方法对该菌株进行鉴定,测定了其对磷酸钙、磷酸铝和磷酸铁的解磷能力,并对该菌株9 d内的磷酸钙溶解动力学进行了研究。结果表明,解无机磷细菌Mp1-Ha4为一株西地西菌Cedecea sp.,其对磷酸钙的溶解能力远强于对磷酸铝和磷酸铁的溶解能力。在NBRIP液体培养基中,该菌株对磷酸钙的溶解能力达到了497.4 mg/L,在其对磷酸钙解磷过程中,培养基pH及可滴定酸度与解磷量分别呈显著负、正相关。高效液相色谱分析显示,该菌株在解磷过程中分泌了大量有机酸,主要包括α-酮戊二酸,酒石酸和苹果酸。分泌有机酸,降低环境pH可能是解无机磷细菌西地西菌(Cedecea sp.)Mp1-Ha4溶解难溶性磷酸盐的主要机制,同时该菌株对磷酸钙的高效溶解作用使其具有较大的研究和应用前景。     

大兴安岭重度火烧迹地恢复后土壤磷形态与解磷细菌分布特征

为了探讨大兴安岭重度火烧迹地恢复后土壤不同磷形态含量、解磷细菌群落结构的差异及两者之间的关系,以人工恢复(樟子松人工林、落叶松人工林)、人工促进天然恢复(次生林)以及天然恢复(天然次生林)的林地土壤为研究对象,采用Sui等修正的Hedley磷素分级法对根际土壤和0～10、10～20 cm非根际土壤进行磷素分级测定,并用高通量测序法得到土壤解磷细菌种群丰度。结果表明: 0～10 cm非根际土壤水溶性磷(H₂O-P_i)、碳酸氢钠无机磷(NaHCO₃-P_i)、碳酸氢钠有机磷(NaHCO₃-P_o)及根际土壤NaHCO₃-P_o含量表现为落叶松人工林>樟子松人工林>天然次生林>次生林。10～20 cm非根际土壤H₂O-P_i、NaHCO₃-P_i、NaHCO₃-P_o及根际土壤H₂O-P_i、NaHCO₃-P_i含量表现为落叶松人工林>樟子松人工林>次生林>天然次生林。不同林分根际与非根际土壤H₂O-P_i、NaHCO₃-P_i和NaHCO₃-P_o含量的比值(R/S)均大于1。中等活性氢氧化钠磷(NaOH-P)包括氢氧化钠无机磷(NaOH-P_i)和氢氧化钠有机磷(NaOH-P_o)。在0～10 cm非根际土壤及根际土壤中NaOH-P含量表现为落叶松人工林>天然次生林>次生林>樟子松人工林,在10～20 cm非根际土壤中表现为落叶松人工林>樟子松人工林>次生林>天然次生林。土壤NaOH-P存在明显的根际效应。酸溶性磷(HCl-P)包括酸溶性无机磷(HCl-P_i)和酸溶性有机磷(HCl-P_o)。在0～10 cm非根际土壤中HCl-P含量表现为落叶松人工林>天然次生林>樟子松人工林>次生林,在10～20 cm非根际及根际土壤中表现为落叶松人工林>樟子松人工林>天然次生林>次生林。土壤残留磷(residual-P)含量对林地恢复方式不敏感。各林分土壤主要解磷细菌均为慢生根瘤菌属、链霉菌属、伯克霍尔德菌属和芽孢杆菌属。樟子松人工林和落叶松人工林土壤解磷细菌丰度显著高于次生林和天然次生林。冗余分析表明,解磷细菌与不同磷形态之间相关性各异。在现阶段来看,人工恢复更有利于提高土壤磷的有效性和增加解磷细菌的丰度。     

盐碱地柠条根围土中黑曲霉的分离鉴定及解磷能力测定

在盐碱滩地的改良过程中,柠条具有提升土壤供氮、供磷、供钾的潜力.以盐碱滩地上建植的柠条灌木林为研究对象,以柠条根围土壤为培养基质,采用无机磷培养基筛选,用平板溶菌圈法分离获得1株具有溶磷能力的真菌.将测得的ITS基因序列在NCBI上进行同源性检索,结果表明,所测序列与黑曲霉(Aspergillus niger)同源性为100％.综合形态特征和ITS基因序列同源性两方面分析,该菌株鉴定为黑曲霉(Aspergillus niger).168h连续监测无机磷培养液pH值、速效磷含量、菌丝重量和菌体吸磷量,研究该菌株的解磷能力.研究结果表明:随着培养时间的延长,培养液pH值从7.0下降到2.0左右,溶液中速效磷含量逐渐增加到4.7 mg,菌体自身吸磷量由5.4 mg下降到0.5mg,在36-48h后各项指标达到稳定状态.可见,黑曲霉菌体可以有效利用难溶性磷源,并将其转化成可被植物吸收利用的有效磷.     

Effect of a phosphate solubilizing bacteria on maize growth and root exudation over four levels of labile phosphorus

The influence of inoculation with phosphate-solubilizing bacteria (Enterobacter agglomerans) on maize growth, P uptake and root exudation was studied. Plants were grown in an axenic culture device where P was supplied as soluble phosphate at different contents (0, 5, 15 or 25 ppm) in the nutrient solution and as insoluble rock phosphate added to the culture sand. Experimental device was successfully used to obtain axenic root systems or good establishment of the inoculated strain in the rhizosphere of maize (10⁹ bact. g⁻¹ dry rhizospheric material). Plant growth was promoted by inoculation only for 5 or 15 ppm of soluble P in the nutrient medium without any significant effect on P uptake by the plant, suggesting that the quantities of P released by bacterial rhizospheric activity were very small. Amounts of organic compounds (total C and water-soluble C) exuded were relatively low (3.0 to 6.4% of the total plant biomass) and were reduced by bacterial inoculation when plant growth was largely promoted. Carbon balance modification and plant growth hormone production by the inoculated strain were suspected and discussed.     

Plant Growth-Promoting Effect of the Chitosanolytic Phosphate-Solubilizing Bacterium Burkholderia gladioli MEL01 After Fermentation with Chitosan and Fertilization with Rock Phosphate

Phosphate-solubilizing bacteria (PSB) are important plant growth-promoting rhizobacteria that can increase soil fertility through the solubilization of insoluble inorganic phosphate and organophosphorus. In this study, a PSB, Burkholderia gladioli MEL01, was isolated and identified from rice–wheat rotation rhizosphere soil. MEL01 had an excellent phosphate-solubilizing capacity (reaching 107.69 mg/L) toward insoluble inorganic phosphate rock phosphate. HPLC analysis revealed that the mechanism of phosphate solubilization of MEL01 was probably due to secreted oxalic acid and gluconic acid transformation of phosphate from insoluble to soluble. MEL01 also exhibited 4030 U/L specific chitosanase activity when cultured with chitosan fermentation medium. Interestingly, the chitosan hydrolysis product chitooligosaccharide could significantly enhance the MEL01 phosphate-solubilizing capacity. Pot experiments showed that MEL01 chitosan medium fermentation liquor (MCMFL) could promote improvement of soil available phosphorus and pakchoi growth when supplemented with phosphate rock phosphate as the phosphate fertilizer. In addition, pot experiments demonstrated that MCMFL could also promote the growth of wheat, which could decrease the amount of compound fertilizer used. Microbial diversity analysis showed that the genera Pseudomonas, Burkholderia, Mycoplana, and Cellvibrio were enriched, which might participate in synergetic phosphate solubilization. Therefore, after fermentation with chitosan and fertilization with rock phosphates, MEL01 has potential as a phosphate biofertilizer in ecological agricultural production.

     

Characterisation of Phosphate Solubilising Bacteria in Sandy Loam Soil Under Chickpea Cropping System

With the aim to explore the possible role of phosphate-solubilizing bacteria (PSB) in phosphorus (P) cycling in agricultural soils, we isolated PSB inhabiting naturally in the sandy loam soils under chickpea cropping of Patiala (Punjab State). A total of 31 bacterial isolates showing solubilizing activities were isolated on Pikovskaya agar plates. The potent phosphate solubilizers were selected for further characterization. These isolates were shown to belong to the genera Pseudomonas and Serratia by partial sequencing analysis of their respective 16S rDNA genes. ERIC-PCR based fingerprinting was done for tracking the survival of introduced populations of the PSB during mass inoculation of these strains under chickpea plots. The results showed positive correlation (r² = 0.853) among soil phosphatase activity and phosphate solubilizers population, which was also positively correlated (r² = 0.730) to available phosphorus. Identification and characterization of soil PSB for the effective plant growth-promotion broadens the spectrum of phosphate solubilizers available for field application.     

一株高效解磷菌的筛选鉴定及溶磷性能

【背景】土壤中大部分磷元素是以难溶性磷酸盐的形式存在,不能被农作物有效利用,而传统化学肥料会带来环境污染等问题。【目的】解决土壤磷缺失现状,开发新型、安全、高效的微生物菌肥。【方法】取武汉科技大学图书馆后土壤为试验材料,筛选出一株高效解磷菌。通过个体形态鉴定、生理生化鉴定、16S rRNA基因序列分析鉴定菌株,以NBRIP为基础培养基进行条件优化,借助高效液相色谱进行细菌解磷机理探究。【结果】所筛选的高效解磷菌株为唐菖蒲伯克霍尔德氏菌(Burkholderia gladioli)。在20种氨基酸中,D-蛋氨酸对菌株的生长和溶磷促进作用最好,促进效果达到19.09%和16.16%,甲酸钠对菌株的生长和溶磷有抑制效果,抑制效果达到39.08%和10.66%。该菌株通过分泌葡萄糖醛酸、D-L-苹果酸等有机酸溶解环境中的磷酸盐,将菌株制作成菌肥对辣椒幼苗有明显的促生长作用。【结论】利用唐菖蒲伯克霍尔德氏菌(Burkholderia gladioli)分泌有机酸溶解土壤中的磷酸盐,可为生物肥料的制备和应用提供一定的理论参考。     

Dephosphorization of LD slag by phosphorus solubilising bacteria

Phosphorus is one of the major nutrients, and microbial solubilisation of insoluble mineral phosphate in soil is an important process in natural ecosystem and in agricultural soil. Many soil microorganisms display the ability to solubilize many insoluble inorganic phosphates. They are generally referred as phosphorus solubilising microorganisms (PSM). In this study an attempt was made to look into the phosphorus solubilisation efficiency of some commonly available soil bacteria and their possible application in bio-beneficiation of metallurgical waste like LD Slag. Linz -Donawitz (LD) slag is produced in large quantities (200 kg LD slag per ton of hot metal) and poses a substantial disposal problem in the iron and steel making industry. LD slag contains around 29% Ca, 21% Fe, and 5% Mg. Its phosphorus content is about 1.5-6%. Due to presence of high amount of Ca, it can be used as flux in blast furnace, but presence of high amount of phosphorus in the LD slag makes them unsuitable for industrial application. Removal of phosphorus with the help of phosphorus solubilising microorganisms may be a great advantage in biotechnological applications. Two gram positive bacteria belonging to genus Bacillus and two gram negative bacteria belonging to genus Pseudomonas were selected in this study. Phosphorus solubilisation efficiency was studied initially with tricalcium phosphate as model insoluble phosphate compound at different sugar concentration, NaCl concentration and at different initial pH of the medium. About 35% of ‘P’ could be solubilized from LD slag by Pseudomonas aeruginosa at 2% solid content.     

Effect of nitrogen form and phosphorus source on the growth,nutrient uptake and rhizosphere soil property of Camellia sinensis L.

The effects of nitrogen form and phosphorus source on the growth, nutrient uptake and rhizosphere soil property of tea (Camellia sinensis L.) were investigated in a pot experiment. The experiment was performed with a compartmental cropping device, which enables the collection of rhizosphere soil at defined distances from the root of tea plant. Nitrogen was supplied as nitrate or ammonium in combination with soluble phosphorus as Ca(H₂PO₄)₂ or insoluble P as rock phosphate. The leaf dry matter production of tea was significantly greater in the treatments with NH₄ ⁺ than NO₃ ^-, whereas dry matter production of root and stem was not significantly affected. Addition of phosphorus as either source did not influence the dry matter production. The concentrations of K in root, Mg and Ca in both the shoot and root supplied with NO₃ ^- were significantly higher than in NH₄ ⁺ and influence of P sources was minor. On the contrary, Al and Mn concentrations were significantly larger in NH₄ ^--fed plants which could be attributed to remarkably increased availability of Al and Mn caused by acidification of the rhizosphere soil (the first 1-mm soil section from the root surface) with NH₄–N nutrition. The concentration of N in shoot was also significantly higher in NH₄- than in NO₃-fed plants, indicating higher use efficiency of NH₄–N. Whatever the phosphate source, rhizosphere pH declined in ammonium compared to in nitrate treatment. The pH decrease was much larger when no P or soluble P were applied and reached 0.85–1.30 units which extended to 3–5 mm away from the root surface. Exchangeable acidity, content of exchangeable Al and Mn were also considerably higher in the rhizosphere soils of NH₄ ⁺ fed tea plants. Significant amounts of P dissolved from rock phosphate accumulated in rhizosphere of NH₄ ⁺, not NO₃ ^-, suggesting that the dissolution of rock phosphate was induced by the proton excreted by tea root fed with ammonium. With soluble P addition, shoot and root P concentrations were greater in NH₄ ⁺ than in NO₃ ^- treatment and it appeared that this difference could not be sufficiently explained by the available P content in soil which was only slightly higher in NH₄ ⁺ treatment. With rock phosphate addition, the shoot and root P concentrations were hardly affected by nitrogen form, although the available P content was much higher and accumulated in the rhizosphere soil supplied with ammonium. The reason for this was discussed with regard to the inter-relationship of Al with P uptake. This revised version was published online in June 2006 with corrections to the Cover Date.