石灰性土壤中解磷优势菌的筛选研究

从石灰性土壤作物根际土样筛选出2株具有较强解P能力的优势菌株“B2”和“B67”,平板培养溶P圈D/d值分别为5.1和3·8,液体摇床培养过程中产生苹果酸、丙二酸、草酸和乳酸等多种有机酸,产酸总量分别为对照的28·25和19.78倍,pH分别较对照下降2.3和1.1,将“B2”和“B67”的培养液分别接种到4个不同地区土壤中恒温恒湿培养20d后测定结果表明,所有土壤中速效磷含量均有所提高,且接种“B2”处理分别为对照的2.64、3.04、1.71和2.20倍,接种“B67”处理分别为对照的2.12、1.90、1.35和1.78倍,且发现其溶P效果和土壤磷酸酶活性与有效活菌数变化趋势基本一致。     

保护性耕作与秸秆还田对土壤微生物及其溶磷特性的影响

试验研究保护性耕作与秸秆还田对土壤微生物及其溶P特性结果表明,免耕和秸秆还田均能促进土壤麦角固醇的增加,而少耕却显著提高土壤微生物生物量。耕作方式间土壤有机碳水平无明显差异,但秸秆还田可提高土壤有机碳含量。免耕处理土壤微生物量显著增加,深耕处理土壤微生物量则较低,秸秆还田微生物量显著高于无秸秆对照。浅耕处理溶P细菌数量最高,免耕最少,但少耕和免耕处理溶P微生物的溶P能力大于深耕及浅耕,秸秆还田对溶P微生物群体和高效溶P菌生长均有促进作用。     

不同AM菌株对酸性土壤玉米生长及磷营养的影响研究

试验研究不同AM菌株对酸性土壤玉米生长及P营养的影响结果表明,6种菌株的菌根形成、菌根效应、菌株根外菌物量均存在显著种间或生态型差异,华北菌株“BEG168”、法国菌株“BEG141”和华南菌株“BEG151”侵染率较高,达20%,而华北菌株“BEG167”次之,华中菌株“HAU-E4”和华南菌株“BEG150”最低。“BEG150”和“BEG168”显著促进玉米地上部和植株的生长,“BEG141”和“BEG151”则无促生效应,而“BEG167”和“HAU-E4”表现为负效应。除“BEG167”降低植物P素吸收外,其余菌株均对宿主P吸收有所增益,其中以“BEG168”和“BEG141”较高。除“BEG167”和“HAU-E4”外其他菌株均有一定应用价值,且以“BEG168”和“BEG150”最有望成为适应酸性土壤的高效真菌。     

真菌与细菌作用下黑云母中主要元素溶出状况的对比分析

以胶质芽孢杆菌(Bacillus mucilaginosus)和棘孢曲霉(Aspergillus aculeatus)分别作为细菌和真菌的代表,进行了黑云母的生物风化实验(为期50 d),研究了微生物作用下黑云母中元素溶出速率和溶出顺序,并对溶解机制进行了初步探讨。利用高效液相色谱仪和电感耦合等离子体发射光谱仪分别测定了培养液中的低分子量有机酸和主要元素(Si、Al、Fe、Mg和K)的浓度。研究结果表明:胶质芽孢杆菌和棘孢曲霉均可促进黑云母的风化;棘孢曲霉的风化速率大约是胶质芽孢杆菌的65倍;真菌与细菌作用下黑云母中元素溶出顺序基本相同,即:层间→八面体晶片→四面体晶片;微生物主要通过分泌低分子量有机酸(酸化环境和络合)来促进黑云母的风化。     

兼具固氮、解磷功能菌株固氮特性的研究

试验研究 9株兼具固N、解P功能菌株在无N、N源充足不同P源条件和混合培养时菌株固N特性结果表明 ,供试菌株在无N培养基上均有固N活性 ,但固N量差异较大 ,菌株“N5 1”固N量最高达 5 5 .4mg/kg ,为固N量最低菌株“K10 2”的 3.1倍。在以Ca3 (PO4) 2 作P源、培养液N素供应充足时“K10 2”和“N17”菌株仍有较高固N能力 ,培养 3d后培养液全N含量增幅达 5 5 .2 % ;“N11”、“N12”和“P14 2”菌株固N量也维持在较高水平 ,全N含量增加30 %左右 ;“K16”菌株培养液全N含量略有增加 ,“N5 1”、“N13 1”和“K3”菌株则导致N的挥发损失。以磷矿粉作P源可使该过程逆转。在Ca3 (PO4) 2 P源培养基上混合培养能有效降低“N5 1”、“N13 1”和“K3”菌株单独培养时所造成的N损失。     

三种溶磷真菌对不同磷源溶解效果的比较研究

报道了溶磷菌株P39(Aspergilusspp.)和P66、P2.3(Penicilliumspp.)在液体培养条件下对5种难溶性磷源的溶解效果。试验结果表明,3种溶磷菌株在所有磷源培养基中生长良好,但它们之间的溶磷量相差很大,菌株P39对不同磷源的溶磷效果为磷酸铁>磷酸铝>磷酸钙>宜昌磷矿粉>摩洛哥磷矿粉,其溶磷率分别达到96.60%、84.00%、66.05%、61.43%和41.52%;P66菌株对不同磷源的溶磷效果为磷酸铝>磷酸钙>摩洛哥磷矿粉>宜昌磷矿粉>磷酸铁,溶磷率分别为78.18%、58.45%、41.09%、33.00%和14.27%;而菌株P2.3对不同磷源的溶磷效果要小于菌株P39和P66,研究结果表明P2.3菌株对磷酸铁不具有溶磷活性,对其它4种不同磷源的溶磷效果为磷酸钙>磷酸铝>摩洛哥磷矿粉>宜昌磷矿粉。对不同菌株培养滤液可滴定酸含量和pH测定结果发现,菌株P39的培养滤液可滴定酸含量与pH值之间存在直线相关,菌株P66和P2.3处理的二者相关性不显著,表明不同的溶磷菌株在不同磷源条件下,可能从有机酸组成和含量两方面发生了变化而影响对难溶性磷的溶解。     

硅酸盐细菌NBT菌株解钾机理初探

摇瓶条件下 ,对硅酸盐细菌NBT菌株发酵液及其代谢产物分解钾长石的作用进行了研究。结果表明 ,培养 48h的NBT菌株发酵液能活化钾长石中的钾、硅、铝。 2 8℃振荡 1 0天后的滤液中K ,SiO2 ,Al2 O3含量分别达 1 84.1、39.8和 1 2 .6mgL- 1 ,分别比灭菌发酵液中的K ,SiO2 ,Al2 O3含量增加 1 0 6 .1 %、63 .1 %和 1 33 .3%。NBT菌株发酵液中含有大量的有机酸、氨基酸、荚膜多糖。摇瓶试验表明 ,三者都有较强的分解钾长石的能力 ,2 8℃振荡 1 0天后的滤液中的K含量分别达 1 1 0 .8、84.9和 1 9.7mgL- 1 。另外 ,三者间有明显的协同作用 ,三者的混合液可使解钾能力提高 62 .2 %。三者分解钾长石的能力是通过酸溶和络合作用来实现的。     

多功能地衣真菌的筛选及其复合菌剂的研制

为了从地衣真菌中筛选高效多功能菌种,研制出高效的微生物菌肥,对地衣真菌采用水解圈法初筛,再分别采用DNS法、钼锑抗比色法、平板对峙法复筛出具有高效降解纤维素、溶解无机磷、抑制病原菌活性的菌株;以不同的菌株组合研制生物菌剂,并进行盆栽试验筛选出促生活性最好的组合。从120株地衣真菌中筛选出高效降解的纤维素菌株为1905-2、1909-7、1913-6、1915-2,其中菌株1905-2和1915-2兼具有抑制病原菌的活性;高效溶磷菌株为1905-4,同时具有抑制病原菌的活性。结合形态学及分子序列鉴定菌株1905-2为高山弯颈霉(Tolypocladium tropicale),1905-4为塔宾曲霉(Aspergillus tubingensis),1909-7为黄曲霉(Aspergillus aflatoxiformans),1913-6为产黄青霉(Penicillium chrysogenum),1915-2为淡紫拟青霉菌(Purpureocillium lilacinum)。组合5(1905-4、1915-2)在增加茎长和鲜重上占有优势,且溶磷效果及降解纤维素效果最好,因此综合选取以组合5研制的生物菌剂作为最终的微生物菌剂。从地衣真菌筛选出高效功能菌株,复合后研制出具有高效降解纤维素、溶解无机磷、抑制病原菌的复合菌剂,旨在为微生物资源的开发与利用、探究研制高产的生态菌肥提供理论基础。     

AM真菌接种对甘薯产量和品质的影响

通过田间试验方法研究了接种AM真菌对甘薯产量和品质的影响。结果表明,种植6周时接种能够提高甘薯的菌根侵染率、生长和吸P量,收获时可提高甘薯的产量和品质。从接种效果看,本地分离的菌株接种效果好于异地分离菌株,混合菌株好于单一菌株。     

溶磷真菌的筛选及配施难溶态磷对土壤磷素有效性的影响

为研究溶磷真菌菌群对土壤磷素有效性的影响,首先在室内对3株不同种类溶磷真菌(1株属于被孢霉属Z1,1株为青霉属Z2,1株为黑曲霉Z3)的组合效应进行了研究,确定了最佳的菌株组合Z1+Z2+Z3,试验选用Z1、Z2、Z3组成菌群作为试验菌株;然后通过盆栽油菜试验研究溶磷真菌配施难溶态磷(磷酸三钙和磷矿粉)对土壤磷素有效性的影响。结果表明:溶磷真菌处理土壤有效磷、有机质、碱性磷酸酶、蔗糖酶含量和油菜产量分别比基质处理显著增加了60.00%,20.21%,56.45%,53.81%,14.38%,溶磷真菌配施难溶态磷上述各指标都高于单施溶磷真菌处理;单施溶磷真菌对土壤最大吸磷量的影响与基质无差异,溶磷真菌配施难溶态磷可以显著降低土壤最大吸磷量,溶磷真菌+磷酸三钙和溶磷真菌+磷矿粉处理土壤最大吸磷量比溶磷真菌处理显著减少158.7,47.6 mg/kg,溶磷真菌各处理土壤吸附常数都低于对应的基质处理,溶磷真菌可以降低土壤对磷的吸附。在土壤上溶磷真菌应与难溶态磷配合施用,对提高土壤磷素有效性有积极的作用。     

Phosphate solubilizing bacteria and fungi in desert soils: species,limitations and mechanisms

Desert soils are infertile, and the ability to improve them by P-fertilization is limited by the solubility of phosphate. We aimed to understand the function of phosphate solubilizing bacteria and the mechanisms behind phosphate solubilization in desert soils. Vegetated and barren desert soils, mine spoil and a fertile temperate grassland loam were sampled. Bacteria and fungi were isolated and identified, and their phosphate-solubilizing abilities were measured in vitro. The release of plant available PO₄, SO₄, NO₃ and NH₄ from desert soils did not compare with that of a grassland soil. Desert soils had substantially lower solubilization than grassland, 162 and 99–121 µg PO₄-P g^?1 dry soil, respectively. Phosphate-solubilizing bacteria and fungi were inhabiting the soils. Si addition increased phosphate solubilization of fungi by 50%. The isolated microbes were shown, using ³¹P nuclear magnetic resonance (NMR) analysis, to rapidly take-up both intracellular and extracellular phosphate during the phosphate solubilizing process. Desert soil had potentially active microbial populations that are capable to solubilize inorganic phosphorus; S and Si as the limiting factors. Acidification as the main mechanism to solubilize mineral phosphate was not as evident in our desert soils as in former studies dealing more fertile soils.     

Phosphate solubilization by a wild type strain and UV-induced mutants of Aspergillus tubingensis

Phenotypic mutants of Aspergillus tubingensis were obtained by UV irradiation and phosphate solubilization ability of these mutants were studied and compared with the wild type strain. Low phosphate solubilizing mutant was also selected in this study. Among the different mutants, AtM-5 and AtM-2 showed highest P solubilization when tri-calcium phosphate and rock phosphate were used as P source compared to the wild type strain and other mutants. These mutants also showed maximum acid phosphatase and phytase activity. These results suggest that P solubilization by these isolates is due to lowering of pH of the culture filtrate and also the activity of acid phosphatase and phytase.     

K_3解磷菌的解磷机理及其对缓冲容量的响应

以对磷酸三钙具有高效溶解作用且对玉米苗生长有促生效果的假单胞菌K3为模式菌株,采用NBRIP液体培养基研究了解磷菌K3的解磷机制及缓冲容量对其解磷量的影响。结果表明,解磷菌K3液体摇瓶培养7 d后,培养液中水溶性磷从6.54μg/mL增加至655.23μg/mL,pH从7.00降至3.99。高效液相色谱测定发现,K3菌液中的主要代谢产物为苹果酸、乳酸和草酸,浓度分别为47.39 mmol/L、25.67 mmol/L和1.89 mmol/L。人工模拟K3菌株产生的有机酸及调节培养基不同pH值对磷酸三钙溶解度影响的试验表明,有机酸的螯合作用是解磷细菌K3菌株解磷的主要机理,而调节培养基pH对解磷的作用有限。液体摇瓶和土培试验结果显示,土壤缓冲容量对K3解磷菌的解磷效应有显著的抑制作用。     

K3解磷菌的解磷机理及其对缓冲容量的响应

以对磷酸三钙具有高效溶解作用且对玉米苗生长有促生效果的假单胞菌K3为模式菌株,采用NBRIP液体培养基研究了解磷菌K3的解磷机制及缓冲容量对其解磷量的影响。结果表明,解磷菌K3液体摇瓶培养7 d后,培养液中水溶性磷从6.54 μg/mL增加至655.23 μg/mL,pH从7.00降至3.99。高效液相色谱测定发现,K3菌液中的主要代谢产物为苹果酸、乳酸和草酸,浓度分别为47.39 mmol/L、25.67 mmol/L和1.89 mmol/L。人工模拟K3菌株产生的有机酸及调节培养基不同pH值对磷酸三钙溶解度影响的试验表明,有机酸的螯合作用是解磷细菌K3菌株解磷的主要机理,而调节培养基pH对解磷的作用有限。液体摇瓶和土培试验结果显示,土壤缓冲容量对K3解磷菌的解磷效应有显著的抑制作用。     

不同种类解磷微生物的溶磷效果及其磷酸酶活性的变化

比较了不同种类的微生物菌株对不同种类难溶性磷酸盐及磷矿粉的溶解能力。结果发现,细菌、酵母、霉菌在解磷方面均有一定作用,发挥着不同优势。磷酸钙、磷酸铝、磷酸铁等难溶性磷酸盐容易被酵母菌、霉菌溶解,而磷矿粉容易被巨大芽孢杆菌溶解,显示不同微生物与不同磷源的亲和溶解能力不同。不同种类磷酸盐或磷矿粉对微生物磷酸酶活力的影响不同,贫磷条件可以促进酸性和碱性磷酸酶活性的增加     

细菌溶磷作用与磷矿粉伴生性重金属元素的释放

以4株溶磷细菌和5种磷矿粉为材料,对细菌溶磷作用与磷矿粉伴生性重金属元素释放间的关系进行了研究。结果表明,溶磷细菌在促进磷矿粉中磷溶出的同时,还促进了磷矿粉中伴生性重金属的释放,在测定的6种伴生性金属元素(Zn、Pb、Cu、Co、Ni、Cd)中,Zn最容易随细菌溶磷作用而释放,最多可占该磷矿粉中总Zn量的97.0%,Pb和Cd随细菌溶磷释放率皆低于10%;细菌溶磷作用强度与磷矿粉中各伴生性重金属释放量间的关系因磷矿粉产地和伴生性重金属种类而异。细菌作用于湖南石门磷矿粉和四川马边磷矿粉的溶磷量与Zn、Cu、Co、Ni释放量间(四川马边磷矿粉中Co除外)正相关,但未达到显著水平(r=0.50~0.95,P>0.05),但在溶解贵州开阳磷矿粉时,Zn、Co、Ni的释放量都与溶磷量显著正相关(r>0.88,P<0.05)。     

Trapping of phosphate solubilizing bacteria on hyphae of the arbuscular mycorrhizal fungus Rhizophagus irregularis DAOM 197198

A simple method is described for trapping phosphate solubilizing bacteria (PSB) strongly attached to the hyphae of the arbuscular mycorrhizal fungus (AMF) Rhizophagus irregularis (Ri). Bacteria were isolated from the hyphosphere of mycorrhizal leek plants growing on Turface previously inoculated with soil suspensions, obtained from the mycorrhizosphere of mycorrhizal plants growing in agricultural settings or maple forests in Quebec, Canada. Among the best PSB strongly attached to the hyphae of Ri, 26 isolates belonged to Burkholderia spp. and one was identified as Rhizobium miluonense. Four hyphobacteria exhibiting high potential of inorganic and organic P mobilization were further compared with four equivalent mycorrhizobacteria directly isolated from mycorrhizospheric soils sampled. In general, hyphobacteria were superior in mobilizing P from hydroxyapatite and from a low reactivity igneous phosphate rock from Quebec. Release of gluconic acid or the product of its oxidation 2-ketogluconic acid, are the main mechanisms involved in P solubilization. In a two compartments Petri plate system, Ri extraradical hyphal exudates, supported PSB growth and activity. In the absence of PSB Ri showed a negligible P solubilization activity. In the presence of PSB a substantial increase in P mobilization was observed, and the superiority of hyphobacterial activity was also observed under this system. Our results suggest that in developing a bioinoculant based on selected PSB, their interaction with AMF hyphae should not be overlooked.     

Effects on yield and nutrition of mycorrhizal and nodulated Pueraria phaseoloides exerted by P-solubilizing rhizobacteria

We studied the effect of bacteria involved in rock phosphate (four isolates), iron phosphate (two isolates), and aluminium phosphate (two isolates) solubilization, and two phytate-mineralizing bacteria in terms of their interaction with two Glomus spp. on Pueraria phaseoloides growth and nutrition. The plant —Rhizobium sp. — mucorrhiza symbiosis system may increase in yield and nutrition in association with specific rhizosphere bacteria that solubilize calcium, iron, and aluminium phosphates. No benefit from phytate-mineralizing bacteria was found under these experimental conditions. P. phaseloides growth responses were influenced in different ways by specific combinations of the selected bacteria and arbuscular mycorrhizal fungi. Considerable stimulation of nutrient uptake was observed with fungus-bacteria combinations of Azospirillum sp. 1, Bacillus sp. 1 or Enterobacter (spp. 1 or 2) associated with G. mosseae. The fact that Bacillus sp. 1, a calcium-phosphate solubilizing isolate, positively interacted with G. mosseae and negatively with G. fasciculatum is an indication of specific functional compatibility between the biotic components integrated in the system. From our results, the interactions between bacterial groups able to solubilize specific phosphate and mycorrhizal fungi cannot be interpreted as occurring only via P solubilization mechanisms since no generalized effect was obtained. Iron-phosphate solubilizing microorganisms were more active alone than in dual associations with Glomus sp., but the aluminium-phosphate dissolving isolates positively interacted in mycorrhizal plants. Further work is needed in this area in order to elucidate the mechanisms that affect rhizosphere microorganism interactions. G. mosseae was more effective but less infective than G. fasciculatum in most of the combined treatments.     

Effect of organic manure on the biological activities associated with insoluble phosphorus release in a blue purple paddy soil

Abstract

This study examined the effects of organic manure and chemical fertilizer on soil microflora, soil respiration, number of inorganic phosphate solubilizing bacteria, and organic phosphorus (P) mineralizing bacteria. The inorganic phosphate solubilizing rate, organic P mineralizing rate, and selected enzyme activities in a blue purple paddy soil were also studied. The results showed that organic manure significantly increased the total number of fungi, actinomyces, bacteria, P solubilizing bacteria, organic P mineralizing bacteria, P solubilizing rate and organic P mineralizing rate, soil respiration rate, and selected enzyme activities, whereas chemical fertilizer resulted in a smaller effect, and bacteria were affected more than fungi and actinomyces by organic manure. The enhancement of biological activities caused by organic manure might be due to the introduction of a large amount of living microorganisms and readily‐utilizable carbon source on which microorganisms live. This study showed that the augment of inorganic phosphate solubilizing bacteria and organic P mineralizing bacteria was one of the reasons that organic manure increased the avilability of P in a blue purple paddy soil.