In vitro toxic effects of heavy metals on fungal growth and phosphate-solubilising abilities of isolates obtained from Phragmites australis rhizosphere

In this research, we evaluated the toxic effect of metal ions on mycelial growth and phosphate-solubilising activity of soil-borne micromycetes isolated from the Phragmites australis rhizosphere using Pikovskaya-agar plates supplemented with four metal concentrations. The diameter growth rate (DGR) decreased as the metal concentration rise for all tested fungi. Trichoderma atroviride had the fastest growth rate (1.48?cm²?day^?1) and was the least susceptible to Al³⁺, Cd²⁺, Cr³⁺, Cu²⁺ and Pb²⁺ with a median effective concentration (MEC₅₀) of 12.19, 0.48, 4.51, 11.44 and 50.05?mM, respectively. Aspergillus japonicus was the most tolerant to Co²⁺, Ni²⁺ and Zn²⁺, with MEC₅₀ values of 3.36, 1.095 and 2.34?mM, respectively. Penicillium italicum was the most tolerant to Cr6⁺ (MEC₅₀?=?0.677?mM). The ability to solubilise phosphate remained, despite the decrease in the DGR, and P. italicum and Penicillium dipodomyicola had the highest Phosphate Solubilisation Indexes (PSIs) at 1.97 and 2.12, respectively. In particular, P. italicum recorded the highest PSI of all the studied isolates at 0.62?mM Cr³⁺ (PSI?=?4.74). A. japonicus and T. atroviride were the most tolerant isolates to all tested metals, which suggests that these isolates are promising candidates for further study with regard to mycoremediation and biofertilisation of metal-polluted soils.     

Antifungal activity of volatile metabolites emitted by mycelial cultures of saprophytic fungi

The antifungal activity of molecular identified Chilean saprobiontic fungi, Trichoderma viride, Schizophyllum commune and Trametes versicolor, on the fungal plant pathogens Botrytis cinerea and Fusarium oxysporum, and the saprotrophic mould Mucor miehei was investigated using two types of inhibition bioassay: (1) bi-compartmented Petri dishes and (2) two Erlenmeyer flasks connected by their upper parts. The chemical composition of volatile organic compounds (VOCs) released by saprobiontic fungi was also investigated using headspace solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC-MS) analysis. Of the saprobiontic fungi evaluated, one isolate of S. commune showed the highest inhibitory activity against B. cinerea and M. miehei, 86.0±5.4 and 99.5±0.5% respectively. The volatile profiles of fungal isolates were shown to contain a different class of compounds. The major components in the headspace of mycelial cultures were 6-pentyl-α -pyrone (T. viride), ethanol and β -bisabolol (S. commune), and a sesquiterpene alcohol (Tr. versicolor). This is the first study reported on the release of VOCs by Chilean native fungi and their antifungal activity wrt. plant pathogenic fungi.     

丛枝菌根对土壤-植物系统中重金属迁移转化的影响

丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)是一类在自然和农业生态系统中广泛存在并能与多数陆生植物形成共生关系的土壤真菌,在重金属污染土壤中对宿主植物的生长及吸收累积重金属具有重要影响,因而对污染土壤的生物修复具有潜在应用价值。以重金属从根际土壤进入植物并在植物体内再分配过程为主线,介绍丛枝菌根在这一过程中对重金属环境行为,特别是根际土壤中重金属赋存形态及植物吸收重金属的影响。最后,对丛枝菌根影响植物重金属耐性机制研究前沿和菌根修复技术的应用前景进行展望。     

草原煤矸石堆放的生态环境问题及其治理措施综述

综述了内蒙古自治区煤矸石排放对草原生态系统造成的危害,比较了物理、化学和生物学方法对治理煤矸石的优缺点,重点分析了丛枝菌根真菌技术在煤矸石山生态重建中的应用及其意义,并提出了当前研究工作中存在的问题及以后的研究重点。     

人工湿地污水处理系统春季空气微生物群落结构分析?

通过构建16S/18S rDNA基因文库,分析自由表面流人工湿地污水处理系统春季空气细菌和空气真菌群落结构特征.结果表明,空气细菌分布在变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)、蓝藻门(Cyanophyta)、绿弯菌门(Chloroflexi)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes),主要为β-变形菌纲(71.04%)、γ-变形菌纲(12.03%)、α-变形菌纲(3.83%)、蓝藻纲(4.38%)、芽孢杆菌纲(3.28%)和鞘脂杆菌纲(2.19%),优势菌属是马赛菌属(Massilia 66.66%)、假单胞菌属(Pseudomonas 4.37%)、蓝丝细菌属(Cyanothece 3.83%)和沙雷氏菌属(Serratia 3.28%).空气真菌主要类群为座囊菌纲(Dothideomycetes 61.18%),其次是接合菌纲(Zygomycetes 16.47%)、盘菌纲(Discomycetes 14.12%),优势菌属是核腔菌属(Pyrenophora 48.31%)、被孢霉属(Mortierella 15.7%)、缘刺盘菌属(Cheilymenia 12.4%)、Boothiomyces (4.5%).人工湿地空气微生物中未检测出大肠杆菌(Escherichia coli)、沙门氏菌(Salmonella spp.)和产气荚膜梭菌(Clostridium perfringens),但存在粘质沙雷氏菌(S. marcescens)、恶臭假单胞菌(P. putida)、表皮葡萄球菌(Staphylococcus epidermidis)等致病菌或条件致病菌.     

中央空调系统过滤器表面真菌鉴定及温热控制

为研究中央空调系统真菌繁殖扩散机理及控制空气微生物污染问题,通过温热控制手段,探究不同温热环境下真菌菌落、菌丝生长繁殖规律.以某体育馆中央空调系统过滤器表面真菌为研究对象,通过分离、生理生化实验和分子生物学鉴定确认空调系统过滤器表面的优势菌属种类及数量.对分离鉴定的优势菌属做温热控制实验,分别在25℃恒温及22℃~28℃变温条件下观察菌落和菌丝的生长规律.结果显示,该空调系统过滤器表面真菌优势菌属为青霉属(Penicillium spp.)和枝孢属(Cladosporium spp.),菌落形成单位分别为600, 140cfu/cm2.温热控制研究表明,无论25℃恒温或22~28℃变温条件,青霉属生长速度都要快于枝孢菌,且菌落直径变化和时间成线性关系;温热控制对青霉属和枝孢菌的生长繁殖具有明显的抑制作用,温热控制技术在抑制空调系统真菌生长上可行.     

Effects of a lead- and cadmium-resistant fungal strain on the absorption of heavy metals by Vetiveria zizanioides北大核心CSCD

A two-factor randomized complete block experiment was used to explore the remediation by a plant-microorganism combination on soils contaminated by lead (Pb) and cadmium (Cd). Factor A was the amount of fungi, for which four values were considered, namely, 0, 1, 3, and 5 g. Factor B was the level of contamination by lead and cadmium, for which six values were considered, namely, Cd0Pb0, Cd10Pb400, Cd20Pb600, Cd30Pb800, Cd50Pb1200, and Cd80Pb1800 (data in units of mg/ kg). The results showed that the resistant fungi promoted the growth of vetiver (Vetiveria zizanioides). At weights of 1, 3, and 5 g, the resistant fungi increased the biomass of vetiver by 41.9%, 74.9%, and 71.7% respectively. The resistant fungi stimulated the absorption of lead and cadmium by both the aerial and underground parts of vetiver. In the presence of 80 mg/kg of Cd2+ and 1 800 mg/kg of Pb2+, the contents of lead in the aerial parts of vetiver were increased by 120.6%, 265.4%, and 242.9%, while the lead content in the underground parts were increased by 110.3%, 278.2%, and 266.2%, after the addition of 1 g, 3 g, and 5 g of fungi, respectively. The content of cadmium in the aerial parts increased by 113.2%, 238.3%, and 217.3%, while the content of cadmium in the underground parts increased by 103.1%, 298.8%, and 274.4%, after the addition of 1 g, 3 g, and 5 g of fungi, respectively. The addition of fungi strengthened the effect of V. zizanioides to remediate soils contaminated by lead and cadmium, and the remediation after the addition of 3 g of fungi was better than that after treatment with 1 g and 5 g of fungi. The combination of resistant fungi and the heavy metal enrichment plant, vetiver, under different concentrations of lead and cadmium showed that the fungi had a significant effect on the remediation of soils contaminated by lead and cadmium. © 2018 Science Press. All rights reserved.     

四川土荆芥精油对植物病原真菌的抗菌活性

以植物病原真菌玉米纹枯病菌Rhizoctonia solani Kuha、玉米弯胞病菌Curvularia lunata（walk）Boed、水稻稻瘟病菌Pyricularia oryzae Cav.、小麦赤霉病菌Gibberellezeae（Schw.）Petch和松赤枯病菌Pestalotia funerea为实验菌,检测了四川土荆芥Chenopodium ambrosioidesL.精油的抑菌活性和抑菌机理。结果表明：培养基给药时,土荆芥精油对5种植物病原真菌均具有抑制作用,IC50分别为：0.734μL·mL-1,0.342μL·mL-1,0.435μL·mL-1,0.370μL·mL-1和0.332μL·mL-1;熏蒸给药时,精油剂量为1μL,土荆芥精油对松赤枯病菌、水稻稻瘟病菌、玉米纹枯病菌和玉米弯胞病菌具有促进作用,高剂量给药对菌丝生长具有抑制作用。半抑制体积分数的土荆芥精油作用于植物病原真菌,菌丝DNA不发生改变,菌丝体结构被破坏,原生质体聚集,蛋白质缺失或增加。     

丛枝菌根真菌对鸢尾的促进作用研究

为高效利用水陆两栖植物鸢尾修复污染水体,本研究通过测定不同的丛枝菌根真菌（AMF）与鸢尾构建共生体系的生长指标、土壤理化性质及植物光合作用指标,探讨不同AMF对水生植物鸢尾的促进作用。结果表明：AMF对鸢尾的促进作用主要体现在地上及地下两部分,其中地下部分通过利用其庞大的菌丝网络吸收土壤中的营养物质,进而促进了鸢尾的生长,其中对比无菌剂侵染的空白植物,摩西球囊霉作用的鸢尾对氮元素的吸收率提高71.75％,磷元素的吸收率提高8.36％,而根内球囊霉作用的鸢尾对氮元素的吸收率提高42.55％,磷元素的吸收率提高9.5％;而地上部分则是通过加强叶片气孔导度的开启来调控植物净光合速率与蒸腾速率之间的平衡,进而提高了鸢尾的最优水资源利用率,加快植物的新陈代谢,最终促进植物的生长发育。其中对于鸢尾光合作用的调节摩西球囊霉的促进效果显著好于（P＜0.05）根内球囊霉。     

Effects of pH and cyclodextrins on pentachlorophenol degradation (mineralization) by white-rot fungi

White-rot fungi (WRF) such as Trametes hirsuta completely degrade (mineralize) pentachlorophenol (PCP) and many other organopollutants. This has led to them being used to decontaminate various substrates (e.g. soil) through biorememediation. However, because PCP is a biocide, it can inhibit fungal growth and thereby its own degradation. It was hypothesized that substrate pH might affect PCP degradation, because when the pH is lower than 4.7 (the pKa for PCP) the phenol predominates, while at higher pH the phenate does. These two PCP species differ markedly in physical and biological properties. The effect of cyclodextrins was also investigated since it is known that the inclusion complexes these form with PCP differ in bioavailability and toxicity from non-complexed PCP. Tests were first made in liquid and agar media (where conditions are relatively easy to control), and then in a sawdust, because it is a common target matrix for WRF bioremediation. Results with the liquid and agar media showed that growth in the presence of inhibitory PCP concentrations decreased as the pH decreased, consistent with the phenol being more toxic. Growth in sawdust was less affected by PCP regardless of the pH, presumably because the PCP sorbed to the wood which decreased its bioavailability. Some cyclodextrins markedly decreased the PCP's toxicity in liquid, agar and sawdust media. Rates of PCP mineralization (measured from production of (14)CO(2) from (14)C PCP) in liquid cultures containing 0.5 mgkg(-1) PCP (a sub-inhibitory concentration) were similar from pH 2.5-7.5, indicating that the phenol and the phenate were equally degradable. Degradation of a growth inhibiting concentration on sawdust (1,000 mgkg(-1)) could be increased slightly by lowering the pH below the pKa, this increasing sorption to the wood. Degradation increased more when the pH was raised well above the pKa, presumably due to the phenate being less toxic and more soluble, making it more available to the degradative system. Although some cyclodextrins decreased growth inhibition, they also interfered with degradation. If this interference could be overcome, cyclodextrins could be used to increase the maximal PCP concentration that could be treated by WRF bioremediation.