123 resultados para fungus isolation


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铊是一种有毒有害的重金属元素,已经引起了广泛的关注。本论文通过对黔西南铊矿区土壤和沉积物样品的菌株分离、铊高耐受性菌株的筛选、胞外吸附、富集、亚细胞水平区系分布、絮凝实验及ITS序列等实验研究分析,并结合铊的地球化学相关研究,较系统地阐述了真菌--铊的生物地球化学过程机理,得出以下结论: 1、与环境背景区相比,黔西南滥木厂铊矿区内的河流、土壤中铊的已有不同程度的积累,直接导致了当地微生物生物量在很大程度上的降低,微生物生物量与铊含量间有显著的负相关关系。研究区内的沉积物、土壤中的微生物区系结构和数量发生了明显变化,细菌、真菌及放线菌数量均出现显著降低,而且三大微生物对重金属污染的敏感性大小也不一样,即放线菌>细菌>真菌。从土壤样品中分离到的主要菌群仍为常见种属,如青霉属(Penicillium)、木霉属(Trichoderma)、拟青霉(Paecilomyces)等。 2、经过初筛菌株的铊耐受性实验,在1000 mg/L水平筛选得到九株高耐受性菌株。吸附实验表明:微生物菌株对铊的吸附效率在4.63~16.89%,且随着环境中铊浓度的上升而降低,这可能是因为铊浓度的升高加大了对微生物生长的抑制作用,所形成的菌丝体(或菌丝球)减少,表面积也相应减少,从而导致了吸附效率的下降。各种常量元素和铊的关系呈显著相关性,钙、钾和钠等常量元素也是微生物赖以维持生存的因子,可能由于微生物细胞对钙、钾的吸附方式与对铊的吸附方式类似。因此,随着铊处理浓度的上升,钙和钾的吸附量也随之减少,而钠则呈现相反的趋势。 3、富集实验表明,九株菌株对铊的富集量随着铊处理浓度上升而降低,其影响趋势与对生物量的影响趋势基本一致,最高可达到7189 mg/kg,最大富集系数为7.2。九株菌株对常量元素的富集与对铊的富集并无明显的相关性,但在考察铊处理浓度对常量元素的富集影响时发现,铊处理浓度的上升与对钙的富集量表现出较强的正相关;而对钾、钠、镁的富集影响并不明显。 4、亚细胞水平上的铊分布研究表明,铊的富集优先顺序为:细胞质>细胞壁>细胞器。亚细胞水平的区隔化作用是微生物对铊的主要耐受机制,细胞质是赋存铊的主要场所(53.83~79.45 %)。结合各亚细胞组分中常量元素与铊之间的相关性,并联系前人的研究,Tl+主要是通过细胞壁的Na+ -K+ ATPase和K+ -电位门通道进入细胞内的从而影响细胞的正常代谢的,而Ca2+的活化更有助于这一过程。 5、絮凝实验表明,培养三天后的发酵液对矿区废水中铊的去除率最高可达到70.49 %,最佳影响因子组合为:pH=8,温度为16℃,搅拌时间为4分钟。菌株的絮凝活性最高可达到57.32%,最佳影响因子组合为:pH=8,温度为14℃,搅拌时间为4分钟。 6、通过对九株铊高耐受性菌株的ITS序列分析及其在Gene Bank中的BLAST比对结果表明,五株菌株同属于木霉属(Trichoderma),两株菌株同属于青霉属(Penicillium)。这表明这两类真菌对铊的适应性较强,为以后寻找铊高耐受性菌株及其资源化利用提供了理论基础。

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An approach for the separation and identification of components in a traditional Chinese medicine Psoralea corylifolia was developed. Ion-exchange chromatography (IEC) was applied for the fractionation of P corylifolia extract, and then followed by concentration of all the fractions with rotary vacuum evaporator. Each of the enriched fractions was then further separated on an ODS column with detection of UV absorbance and atmospheric pressure chemical ionization mass spectrometer (APCI/MS), respectively, and also analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) with matrix of oxidized carbon nanotubes. Totally more than 188 components in P. corylifolia extract were detected with this integrated approach, and 12 of them were preliminary identified according to their UV spectra and mass spectra performed by APCI/MS and MALDI-TOF/MS. The obtained analytical results not only demonstrated the powerful resolution of integration IEC fractionation with reversed-phase liquid chromatography (RPLC)-APCI/MS and MALDI-TOF/MS for analysis of compounds in a complex sample, but also exhibited the superiority of APCI/MS and MALDI-TOF/MS for identification of low-mass compounds, such as for study of traditional Chinese medicines (TCMs) and metabolome. (c) 2005 Published by Elsevier B.V.