喀斯特灌丛土壤丛枝菌根真菌群落结构及丰度的影响因子

运用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)和荧光定量PCR(real-time PCR)法,检测喀斯特灌丛生态系统中不同坡位条件下土壤丛枝菌根(arbuscular mycorrhizal,AM)真菌群落结构与丰度的变化,揭示不同坡位条件下影响灌丛生态系统土壤AM真菌群落结构与丰度的关键因子.研究结果表明不同坡位条件下,土壤有机碳、全氮和速效磷含量差异显著,变化趋势为上坡位≈中坡位下坡位;土壤AM真菌丰度变化趋势为上坡位≈中坡位下坡位.相关性分析表明,土壤速效磷含量与AM真菌丰度存在显著负相关(P0.05).RDA分析表明不同坡位条件下,土壤AM真菌与植物群落结构存在显著差异,植物均匀度指数显著影响土壤AM群落结构组成,而土壤有机碳、全氮显著影响植物群落结构组成.可见,不同坡位条件下,土壤养分与植物群落结构共同作用影响土壤AM真菌群落结构,说明利用AM真菌用于喀斯特地区植被恢复时,微形态(坡位)对AM真菌的影响应该纳入考虑范畴.     

多氯联苯污染土壤菌根真菌-紫花苜蓿-根瘤菌联合修复效应

选用紫花苜蓿（Medicago sativa L.）作为宿主植物,盆栽试验研究了丛枝菌根真菌（Glomus caledonium）和苜蓿根瘤菌(Rhizobium meliloti)单接种及双接种对PCBs复合污染土壤的联合修复效应.结果表明,在紫花苜蓿-菌根真菌-根瘤菌共生体系中,紫花苜蓿对土壤中PCBs的降低起到明显作用,使轻度污染和重度污染土壤中PCBs浓度分别下降了15.8%、 23.5%,紫花苜蓿单接种菌根真菌和苜蓿根瘤菌后轻度污染和重度污染土壤中PCBs浓度分别下降了14.8％、 24.1%和20.6%、 25.5%,双接种后土壤PCBs分别降低了23.2％、26.9%,而且也改变了紫花苜蓿根际土壤微生物群落的碳源利用程度,改善了微生物群落功能多样性.可见,紫花苜蓿豆科植物-菌根真菌-根瘤菌特殊共生体对PCBs污染土壤显示了较好的修复潜力.     

丛枝菌根根际细菌群落对阿特拉津胁迫的响应

为了探求丛枝菌根(Arbuscular Mycorrhiza,AM)根际细菌群落对阿特拉津胁迫的响应,本试验以摩西管柄囊霉(Funneliformis mosseae)为供试AM真菌菌株,以紫花苜蓿(Medicago sativa)为宿主植物,利用盆栽法建立AM共生体后,再施加10 mg·kg-1阿特拉津进行胁迫.当阿特拉津去除率达到50%时,分别采集未接种+未施药(NM.NA)、接种+未施药(AM.NA)、未接种+施药(NM.AT)和接种+施药(AM.AT)4种处理的根际土壤,通过16S rRNA V4高通量测序技术解析了根际土壤细菌群落特征,以及其与接种F.mosseae、施加阿特拉津之间的相关性.结果表明,变形菌门(Proteobacteria)、放线菌门(Actinobacteria)和厚壁菌门(Firmicutes)为4种处理根际土壤中的三大优势菌群.单独接种F.mosseae或施加阿特拉津均未对根际细菌群落α-多样性产生显著影响,但先接种F.mosseae形成AM后,施加阿特拉津可引起细菌群落Shannon指数显著增加.此外,接种F.mosseae提高了根际土壤中具有阿特拉津降解潜力菌属Arthrobacter、Mycobacterium、Frankia和Stenotrophomonas的相对丰度,其中,Arthrobacter受F.mosseae、阿特拉津及其二者交互作用的显著性影响.本研究结果在一定程度上揭示了AM间接提高土壤中具有阿特拉津降解潜力菌属的相对丰度,也可为利用AM真菌修复阿特拉津污染土壤奠定一定的理论基础.     

大麻茎腐病菌的分离及其对土壤环境影响的研究

从病变部位分离出两株病原真菌DN1和DN2,通过茵丝及孢子形态的观察,初步确定其分别为半知菌亚门链格孢属（Altemaria altemata）及轮枝孢属（M．Verticillium）。在pH值4～14之间,两株菌都能正常生长,对环境的适应能力较强。通过盆栽试验确定大麻对土壤pH的影响,结果表明大麻能修复弱碱性土壤。     

黑麦草、丛枝菌根对番茄Cd吸收、土壤Cd形态的影响

采用大田试验研究了在重金属Cd(5.943 mg·kg~(-1)污染下,黑麦草和丛枝菌根对2个品种番茄("德福mm-8"和"洛贝琪")生长、Cd含量以及对土壤微生物、酶活性、p H和Cd形态的影响.结果表明,黑麦草和丛枝菌根单一或复合处理显著提高了2个品种番茄果实、根、茎、叶和植株总干重,增幅分别为14.1%~38.4%和4.2%~18.3%、20.9%~31.5%和8.4%~10.3%、13.0%~16.8%和3.0%~9.5%、10.7%~16.8%和2.7%~7.6%、14.3%~36.6%和4.5%~16.8%.黑麦草和丛枝菌根单一或复合处理增加了土壤中细菌、真菌、放线菌数量及土壤脲酶、转化酶、磷酸酶、过氧化氢酶活性,且土壤微生物数量及土壤酶活性在不同品种和处理间的差异达到显著性水平(P0.05).与番茄套种黑麦草或接种丛枝菌根提高了土壤p H值,降低了土壤中可交换态(EXC-Cd)、碳酸盐态(CAB-Cd)和铁锰氧化态(Fe-Mn-Cd)和土壤中Cd总量,土壤中Cd总量降幅为16.9%~27.8%.2个番茄品种果实、叶、茎和根中的Cd含量分别显著下降了6.9%~40.9%、5.7%~40.1%、4.6%~34.7%和9.8%~42.4%.Cd主要积累在番茄的叶、根和茎中,果实积累较少.比较供试的2个番茄品种,果实Cd含量和积累量及植株Cd总积累量以"洛贝琪""德福mm-8".     

净化SO2的生物膜填料塔中微生物类群分析

对净化废气中SO2的生物膜填料塔内的微生物进行了分离纯化并做鉴定,得到一株嗜酸性氧化硫硫杆菌（Acidithiobacillus thiooxidans IEL001）和一株分类地位非常接近链二孢属（Bispora sp.）的极端嗜酸真菌IEL002,生物膜填料塔内的极端酸性环境和有机营养的缺乏导致生物膜上的微生物种类较为单一,多样性程度不高。本研究还发现IEL002自身并不能氧化单质硫,但它能促进Acidithiobacillus thiooxidans IEL001对单质硫的氧化。     

The Influence of Mycorrhiza on Uranium and Phosphorus Uptake by Barley Plants from a Field-contaminated Soil (7 pp)

Background Recent studies indicated that arbuscular mycorrhizal fungi (AMF) play important roles in plant accumulation of uranium (U) from contaminated environments, but the impacts of fertilization practices on functioning of the symbiotic associations, which are crucial factors influencing plant nutrition and growth responses to mycorrhiza, have rarely been considered. Materials and Methods In a greenhouse experiment, a bald root barley mutant (brb) together with the wild type (wt) were used to test the role of root hairs and AMF in uranium (U) uptake by host plants from a U contaminated soil. Nil, 20 and 60 mg KH2PO4-P kg–1 soil were included to investigate the influences of phosphorus (P) fertilization on plant growth and accumulation of U. Results Dry matter yield of barley plants increased with increasing P additions and wt produced significantly higher dry weight than brb. Mycorrhiza markedly improved dry matter yield of both genotypes grown at nil P, whereas only brb responded positively to mycorrhiza at 20 mg P kg-1. At the highest P level, mycorrhiza resulted in growth depressions in both genotypes, except for the roots of wt. In general, plant P concentrations increased markedly with increasing P additions and in response to mycorrhiza. Mycorrhiza and P additions had no significant effects on shoot U concentrations. However, root U concentrations in both genotypes were significantly increased by mycorrhiza. On the other hand, shoot U contents increased with increasing P levels, while 20 mg P kg-1 stimulated, but 60 mg P kg-1 marginally affected the U accumulation in roots. Root length specific U uptake was moderately enhanced both by root hairs and strongly enhanced by mycorrhiza. Moreover, non-inoculated plants generally had higher shoot-root ratios of U content than the corresponding inoculated controls. Conclusion Our study shows that AMF and root hairs improves not only P acquisition but also the root uptake of U, and mycorrhiza generally decreases U translocation from plant root to shoot. Hence, mycorrhiza is of potential use in the phytostabilization of U contaminated environments. Perspectives The complex impacts of P on U accumulation by barley plants suggested that U behavior in mycorrhizosphere and translocation along the soil-fungi-plant continuum as affected by fertilization practices deserve extensive studies for optimizing the function of mycorrhizal associations for phytoremediation purposes.     

Arbuscular mycorrhizal fungi, rhizobia, available soil P and nodulation of groundnut (Arachis hypogaea) in Zimbabwe

Arbuscular mycorrhizal fungal (AMF) colonization and nodulation of groundnut were examined in nine soils collected from subsistence farmers’ fields in Zimbabwe. Nodule number, shoot dry weight, shoot N and P contents, and AMF colonization were assessed after 6 weeks growth. Both nodule number and AMF colonization differed by an order of magnitude among the nine soils. Soil available P explained almost all the variability in nodule number (r² = 0.98), but had no significant effect on percent AMF colonization. By adding P to one soil, nodule numbers increased four-fold resulting in a significantly higher N content in the shoots. Similar, but smaller, effects were obtained by increasing the abundance of AMF through an inoculation with Glomus intraradices, suggesting that nodulation in this soil was limited by AMF abundance and that the fungi could, to a limited extent, substitute for P fertilizer.     

日光辐射对大气真菌粒子的影响

大气中真菌粒子的衰亡和净化，除与真菌自身的因素有关外，与日光辐射也有密切关系。此文现场观测了日光辐射对大气真菌粒子的影响。结果表明，一天内大气真菌粒子浓度与日光辐射强度呈反比：大气真菌粒数直径中值与日光辐射强度呈正比：随着日光辐射强度的增大，＜３．０μｍ的大气真菌粒子，其浓度减小的速度比＞３．０μｍ的快。     

白腐真菌降解经微电解预处理二硝基重氮酚废水的研究

利用自行培养、驯化的白腐真菌,对经过微电解预处理的二硝基重氮酚(DDNP)废水进行了生物降解试验.结果表明,经过微电解预处理后的DDNP废水(含CODCr467 mg/L)经生化处理108 h后,出水中CODCr在131 mg/L左右,达到国家二级排放标准;其中的苯胺类、硝基类的去除率达到99.9%以上,达到国家一级排放标准.对试验所获得的时间序列进行动力学研究结果证明,白腐真菌降解经微电解预处理后的DDNP废水的反应为准一级动力学反应.