三株高效秸秆纤维素降解真菌的筛选及其降解效果

【目的】利用多种筛选方法,获得高效秸秆纤维素降解真菌,并研究其秸秆纤维素的降解能力。【方法】采用滤纸片孔洞法、滤纸条降解法、羧甲基纤维素钠(CMC-Na)水解圈测定法、秸秆失重法、纤维素分解率测定法、胞外酶活测定法等常规秸秆纤维素降解菌的筛选方法。【结果】筛选到3株具有较强纤维素降解能力的真菌菌株,经初步鉴定菌株98MJ为草酸青霉(Penicillium oxalicum)、菌株W3为木霉(Trichoderma sp.)、菌株W4为扩张青霉(Penicillium expansum)。菌株W4具有非常强的秸秆纤维素降解能力,10d内对秸秆的降解率可达56.3%,对纤维素、半纤维素和木质素的分解率分别为59.06%、78.75%和33.79%。菌株W4的胞外纤维素酶活力在14.25-49.75U/mL之间。【结论】筛选获得3株高效秸秆纤维素降解真菌菌株,其中菌株W4的纤维素酶活高于已报道的菌株,是一株十分具有研究开发潜力的纤维素酶生产菌株。     

植物精油对金针菇保鲜效果的研究

为开发天然绿色的食用菌专用型保鲜剂,对4种植物精油抑制黑曲霉(Aspergillus niger)、产黄青霉(Penicillium chrysogenum)、绿色木霉(Trichoderma viride)和木霉(Trichoderma sp.)等病原真菌的效果进行分析,并以金针菇为材料进行初步保鲜效果评价。研究结果显示,薰衣草精油对黑曲霉的抑制率最高,为17.86%,柠檬醛对产黄青霉及木霉的抑制率最高,分别为16.69%和34.41%,而茴香油则对绿色木霉的抑制率最高,达17.39%。经柠檬醛处理的金针菇在保鲜过程中,失重率、褐变度被显著抑制,还原糖含量增加,CAT活性降低的趋势被减缓。这些指标均显示柠檬醛具有较好的保鲜效果,是开发天然绿色保鲜剂的良好材料。     

水稻秸秆还田时间对土壤真菌群落结构的影响

为揭示水稻秸秆还田对土壤真菌群落结构的长期影响,采用荧光定量PCR和PCR-DGGE技术分析了秸秆还田90,180,270 d和360 d的土壤真菌基因丰度和群落结构组成演变趋势,并利用冗余分析(RDA)研究土壤真菌群落结构变化与环境因子的关系。结果表明:随着秸秆还田时间的增加,土壤真菌群体数量和多样性指数(H、R和E)显著增加,在360 d时达到最高。对DGGE图谱的特征条带进行胶回收、测序,系统进化分析表明,土壤真菌主要种群包括:接合菌(Zygomycete sp.)、盐腐霉菌(Pythium salinum)、肉盘菌(Uncultured Sarcosomataceae)、牛粪盘菌(Ascobolus stercorarius)、大链壶菌(Lagenidium giganteum)、青霉菌(Penicillium sp.)、曲霉属真菌(Aspergillus sp.)和疏绵状丝孢菌(Thermomyces lanuginosus)、灰绿曲霉菌(Aspergillus glaucus)、禾谷多粘菌(Polymyxa graminis)和枝顶孢霉菌(Acremonium sp.),其中青霉菌(Penicillium sp.)、曲霉属真菌(Aspergillus sp.)和枝顶孢霉菌(Acremonium sp.)具有纤维素降解能力,而枝顶孢霉菌(Acremonium sp.)在90 d时成为新的优势菌群。RDA分析表明,90 d和180 d秸秆还田与对照土壤的真菌群落结构较为类似,270 d和360 d的秸秆还田与对照土壤的真菌群落结构发生了明显变化。土壤有机碳、pH和速效磷是引起土壤真菌群落结构及多样性变异的主要因素。     

杉木叶片内生真菌定殖对凋落物分解及其微生物活性的影响

【背景】植物内生真菌在植物组织由衰亡转入腐生过程中发挥重要的作用,但这种作用可能因植物及其内生真菌种类不同而具有差异。【目的】分析不同优势度种类内生真菌定殖对于凋落物分解及其相应微生物活性的影响。【方法】采用凋落物分解袋法,选取优势树种杉木凋落叶作为分解底物。【结果】不同优势度类型的内生真菌单菌或组合定殖在分解过程前期几乎均显著加速了凋落物分解,而在分解后期,除了Irpex lacteus和Colletotrichum sp.,这种加速效应几乎均在减弱,甚至抑制了分解过程。微生物活性各变量对内生真菌定殖处理的响应与失重率并不完全一致,这依赖于分解时期。CO2释放速率在前期与失重率相关性不强,而后期则密切相关;分解前期羧甲基纤维素酶(carboxymethylcellulase,Cx酶)对失重率贡献较大,然而后期漆酶与过氧化物酶对失重率的贡献升高。总之,内生真菌定殖对凋落物分解及相应的微生物活性均产生了较大影响。【结论】对内生真菌定殖效应的研究有助于人们对森林生态系统土壤碳库平衡和养分循环维持机制的理解,同时对于贫瘠人工林土壤肥力的恢复研究也具有重要的意义。     

真菌产3种β-D- Glucuronidase酶学性质

分离筛选到能代谢甘草酸并产生不同产物的3株菌株,其中Penicillium sp.Li-3转化甘草酸生成GAMG,As-pergillus sp.Li-20生成GAMG和甘草次酸,Aspergillus sp.Li-62生成甘草次酸。对这3株菌表达β-D-葡萄糖醛酸苷酶的酶学性质进行了研究,结果表明:Penicillium sp.Li-3、Aspergillus sp.Li-20和Aspergillus sp.Li-62β-D-葡萄糖醛酸苷酶最适催化pH分别为4.2~4.6,5.8和6.2,最适催化温度为50、45和55℃。Penicillium sp.Li-3表达的β-D-葡萄糖醛酸苷酶Km为0.328μmol/L,Vmax为0.003 5 mmol/(L.min);Aspergillus sp.Li-20β-D-葡萄糖醛酸苷酶Km为3.61 mmol/L,Vmax为0.034 mmol/(L.min);而Aspergillus sp.Li-62β-D-葡萄糖醛酸苷酶Km为0.43 mmol/L,Vmax为0.106 mmol/(L.min)。     

遗址木构件有害真菌的快速测定方法

介绍了1种快速测定遗址木构件有害真菌的方法:用孢子菌丝悬浮液直接接种于供试木块上,培养4d,即可确定其侵染性;培养8d,即可确定其侵染力。应用该方法成功地测定了灰绿曲霉(Aspergillus glau-cus)、黑曲霉(Aspergillus niger)、枝孢霉(Cladosporiumsp.)、顶青霉(Penicillium corylophilum)、柑桔青霉(Penicilliumcitrinum)、团青霉(Penicillium commune)、黄曲霉(Aspergillus flavus)、微紫青霉(Penicilliumjanthinellum)、总状毛霉(Mucor racemosus)、绿木霉(Trichoderma viride)等10种真菌的侵染性和侵染力。     

一株南海指海绵共附生真菌多样性及其抗菌活性

本研究通过采用6种不同的培养基对南海指海绵上的共附生真菌进行平板涂布法分离培养,结合ITS-rDNA基因序列特征和形态学特征进行鉴定来研究海绵共附生真菌多样性。共分离培养出55株(21种)真菌菌株,优势菌属为木霉菌属Trichoderma sp.(31株),其中的哈茨木霉Trichoderma harzianum 22株作为优势菌种,占真菌菌株总数的40%。其余真菌则属于枝孢菌属Cladosporium、迈耶氏酵母属Meyerozyma、茎点霉属Phoma、红酵母属Rhodotorula、青霉菌属Penicillium、曲霉属Aspergillus等10个属,还有两株未鉴定到种的子囊菌。选取金黄色葡萄球菌Staphylococcus aureus等7种病原指示菌,采用琼脂扩散法对21种真菌的代表性菌株进行抗菌活性筛选,其中有3种真菌至少对一种指示菌表现出抑菌效果,占菌株种类总数的11%。     

南海局部海洋沉积物中真菌多样性及产酶活性

【目的】从11份南海海洋沉积物中分离耐盐真菌,并对其物种多样性及产酶活性进行研究。【方法】利用平板涂布法分离耐盐真菌,基于形态学和ITS序列的系统进化研究耐盐真菌多样性;利用6种筛选培养基对耐盐真菌进行产酶活性筛选。【结果】分离得到1689株耐盐真菌,共41个形态种。形态学和ITS序列分析表明,这些真菌归于15个属,其中曲霉属(Aspergillus)和青霉属(Penicillium)为优势菌群。对已测序的41株耐盐真菌的产酶活性研究表明,8株产纤维素酶,9株产淀粉酶,5株产复合酶,16株产蛋白酶,3株产脂肪酶,未发现产壳聚糖酶的菌株,其中Acrodontium sp.8m和Aspergillus sp.86b产复合酶的活性相对较高,而Penicillium sp.41m产蛋白酶的活性相对较高。【结论】南海局部海洋沉积物中耐盐真菌丰富,多数菌株具有产酶活性。     

内生真菌促进玉米幼苗的抗旱性研究

在温室盆栽条件下,将从玉米中分离的内生真菌Alternaria sp.AS1113、Chaetomium sp.AS1221、Colletotrichum sp.AS1716和Penicillium sp.AS1618回接到玉米幼苗根系,并进行正常水分和干旱胁迫培养处理。结果表明在正常水分和干旱胁迫下,与不接菌对照相比,接种Chaetomium sp.AS1221和Penicillium sp.AS1618显著提高玉米幼苗的株高。与不接菌对照相比,在正常水分下接种4种内生真菌对玉米幼苗的地上、地下和总生物量均无显著影响,而在干旱胁迫下接种Chaetomium sp.AS1221显著提高玉米幼苗的地上生物量,接种Chaetomium sp.AS1221和Penicillium sp.AS1618显著增加玉米幼苗的地下生物量和总生物量。在正常水分和干旱胁迫下,接种Chaetomium sp.AS1221和Penicillium sp.AS1618的玉米幼苗的地上生物量、地下生物量和总生物量均显著高于接种Alternaria sp.AS1113。与不接菌对照相比,在正常水分下接种Alternaria sp.AS1113显著降低玉米幼苗叶的可溶性糖含量,接种Colletotrichum sp.AS1716和Penicillium sp.AS1618显著降低玉米幼苗叶的过氧化物酶(POD)活性,而在干旱胁迫下接种4种内生真菌对玉米幼苗根系和叶的可溶性糖含量和POD活性均无显著影响。结果表明内生真菌Chaetomium sp.AS1221和Penicillium sp.AS1618对促进玉米幼苗的抗旱能力效果好于Alternaria sp.AS1113和Colletotrichum sp.AS1716。     

不同真菌纤维素酶一些生物化学性质的比较

比较了属于6个属,即青霉(Penicillium)、曲霉(Aspergillus)、木霉(Trichoderma)、漆斑菌(Myrothecium)、镰孢霉(Fusarium)和腐质霉(Humicola),总计9株真菌在麦麸液体培养基中所产纤维素酶的一些生物化学性质。此外,还比较了这9株真菌在麦麸固体培养基上所产纤维素酶的活力以及对脱脂棉、水曲柳木屑、水曲柳木粉、废报纸和玉米芯糠醛废渣的糖化能力。     

Role of phyllosphere fungi of forest trees in the development of decomposer fungal communities and decomposition processes of leaf litter

The ecology of endophytic and epiphytic phyllosphere fungi of forest trees is reviewed with special emphasis on the development of decomposer fungal communities and decomposition processes of leaf litter. A total of 41 genera of phyllosphere fungi have been reported to occur on leaf litter of tree species in 19 genera. The relative proportion of phyllosphere fungi in decomposer fungal communities ranges from 2% to 100%. Phyllosphere fungi generally disappear in the early stages of decomposition, although a few species persist until the late stages. Phyllosphere fungi have the ability to utilize various organic compounds as carbon sources, and the marked decomposing ability is associated with ligninolytic activity. The role of phyllosphere fungi in the decomposition of soluble components during the early stages is relatively small in spite of their frequent occurrence. Recently, the roles of phyllosphere fungi in the decomposition of structural components have been documented with reference to lignin and cellulose decomposition, nutrient dynamics, and accumulation and decomposition of soil organic matter. It is clear from this review that several of the common phyllosphere fungi of forest trees are primarily saprobic, being specifically adapted to colonize and utilize dead host tissue, and that some phyllosphere fungi with marked abilities to decompose litter components play important roles in decomposition of structural components, nutrient dynamics, and soil organic matter accumulation.     

抚育间伐对油松人工林下大型真菌的影响

真菌在森林凋落物分解过程中起重要作用,研究间伐如何影响真菌进而影响凋落物分解,对深入了解间伐调控人工林凋落物分解有重要意义。本文以抚育间伐后的中龄油松人工林为研究对象,设立对照（I）、轻度（II）、中度（III）和强度（IV）4种间伐强度,于2011年对间伐后林下大型真菌进行两次调查,分析了不同间伐强度下大型真菌的科的分布、优势种组成和生态指标（包括丰富度指数、多样性指数和均匀度指数）。结果表明：（1）8月、9月采集到的大型真菌分别为35种和25种,分属13个科和10个科;（2）在大型真菌出菇期,间伐改变了大型真菌的优势种组成,对照林下大型真菌优势种最初为外生菌根菌（粘盖乳牛肝菌 血红铆钉菇）后变为腐生菌（大盖小皮伞和脐顶小皮伞）,而间伐后林下优势种始终为腐生菌;（3）间伐影响大型真菌的生态指标,中度间伐林下大型真菌丰富度和多样性指数最高。总之,适度间伐不仅有利于提高林下大型真菌的丰富度与多样性,同时使其群落结构发生改变,群落优势种由外生菌根菌变为以分解凋落物为主的腐生菌,可促进凋落物的分解和养分循环。     

Review of mixed forest litter decomposition researches

The litter plays an important role in forest ecosystems. Decomposition of mixed leaf litters has recently become an active research area because it mimics the natural state of leaf litters in most of forests. Many studies reported effects of mixing litters on their decomposition, ranging from positive, negative to neutral. In this paper decomposition mechanisms of mixed litters concluded by researchers were summarized. Firstly, plant litter quality had been recognized as an important factor to affect decomposition rate. Some studies showed a positive significant correlation between initial N, P concentration and non-additive effect in litter mixture decomposition. Secondly, it has been suggested that litter mixture could increase abundance and diversity of fauna and microbial decomposers, especially fungi. Thirdly, compared with single litter decomposition, the nutrient exchange between different litter species is often considered as one of main non-additive effects observed in litter mixture. Some results showed that the active transport of nutrients by fungal hyphae derived positive effect on the decomposition of litter mixture. The multiple factors such as, leaf litter species, investigation method and plot, were also analyzed. In conclusion, it is necessary to enhance a further research on factors in mixed litter decomposition and an interaction between various factors due to the complex relationship. We are looking forward to using these theories of mixed litter decomposition to direct practical forest management.     

Review of mixed forest litter decomposition researches

The litter plays an important role in forest ecosystems. Decomposition of mixed leaf litters has recently become an active research area because it mimics the natural state of leaf litters in most of forests. Many studies reported effects of mixing litters on their decomposition, ranging from positive, negative to neutral. In this paper decomposition mechanisms of mixed litters concluded by researchers were summarized. Firstly, plant litter quality had been recognized as an important factor to affect decomposition rate. Some studies showed a positive significant correlation between initial N, P concentration and non-additive effect in litter mixture decomposition. Secondly, it has been suggested that litter mixture could increase abundance and diversity of fauna and microbial decomposers, especially fungi. Thirdly, compared with single litter decomposition, the nutrient exchange between different litter species is often considered as one of main non-additive effects observed in litter mixture. Some results showed that the active transport of nutrients by fungal hyphae derived positive effect on the decomposition of litter mixture. The multiple factors such as, leaf litter species, investigation method and plot, were also analyzed. In conclusion, it is necessary to enhance a further research on factors in mixed litter decomposition and an interaction between various factors due to the complex relationship. We are looking forward to using these theories of mixed litter decomposition to direct practical forest management.     

Relationships between the litter colonization by saprotrophic and arbuscular mycorrhizal fungi with depth in a tropical forest

Fungal colonization of litter has been described mostly in terms of fructification succession in the decomposition process or the process of fungal ligninolysis. No studies have been conducted on litter colonization by arbuscular mycorrhizal fungi (AMF) and their relationship with the presence of saprotrophic fungi. The aim of the present study was to evaluate the relationships that exist in simultaneous leaf litter colonization by AMF and saprotrophic fungi and the relationships between rates of litter and associated root colonization by AMF at different soil depths. We selected Eugenia sp. and Syzygium sp. in a riparian tropical forest, with an abundant production of litter (O horizon), we evaluated litter and root colonization at different depths, its C:N ratios, and the edaphic physico-chemical parameters of the A horizon immediately below the litter layer. Litter colonization by saprotrophic fungi and AMF increased with depth, but the saprotrophic fungal colonization of some litter fragments decreased in the lowermost level of the litter while AMF litter colonization continued to increase. Plant roots were present only in the middle and bottom layers, but their mycorrhizal colonization did not correlate with litter colonization. The external hyphae length of AMF is abundant (ca. 20 m g(-1) sample) and, in common with sample humidity, remained constant with increasing depth. We conclude that in zones of riparian tropical forest with abundant sufficient litter accumulation and abundant AMF external hyphae, the increase in litter colonization by AMF with depth correlates to the colonization by saprotrophic fungi, but their presence in the deepest layers is independent of both litter colonization by saprotrophic fungi and root colonization by AMF.     

森林凋落物研究进展

对森林凋落物的概念、研究方法及主要研究内容作了阐述,特别就凋落物收集面积和分解袋孔径大小、凋落量时空动态和凋落物分解速率等问题进行了综合分析。目前森林凋落物研究的重要结论有：海拔和纬度因子是通过对光、温、水等生态因子的再分配来影响凋落量,其中主导气候因子是年均温。凋落物的分解与化学组成和环境因子有关,C／N和N含量在凋落物分解过程中起着重要作用。土壤水分是影响凋落物分解主要环境因子之一;土壤微生物对凋落物的影响,前期是通过真菌破碎凋落物表层使内居性动物得以侵入凋落物内部,后期则以细菌降解有机物为主。凋落量、凋落物分解的影响因子,以及凋落物的生态作用等内容应是凋落物研究的重要方向。     

Ecology of ligninolytic fungi associated with leaf litter decomposition

Advances in our understanding of the decomposition processes in forest ecosystems over the past three decades have demonstrated the importance of lignin as a regulating factor in the decomposition of leaf litter. Consequently, increasingly more attention is being focused on the ecology of fungi associated with lignin decomposition. The aim of this review is to provide a critical summary of the ecology of ligninolytic fungi inhabiting leaf litter and forest floor materials. The review focuses on the following aspects of ligninolytic fungi: the taxonomic and functional diversity of ligninolytic fungi, the outcomes of interactions between ligninolytic fungi and other organisms, the activity and abundance of ligninolytic fungi measured by the production of bleached leaves and humus, the activity of ligninolytic enzymes in soil environments, the substratum and seral succession, spatial and temporal patterns in both mycelial abundance and species distribution, and the effect of environmental factors such as nitrogen deposition and global environmental changes on ligninolytic fungi. This review integrates the ecology, diversity, and activity of ligninolytic fungi into the context of an ecosystem in order to provide an understanding of the roles of ligninolytic fungi in decomposition processes. Takashi Osono is the recipient of the 11th Denzaburo Miyadi Award.     

Influence of Different Forest System Management Practices on Leaf Litter Decomposition Rates,Nutrient Dynamics and the Activity of Ligninolytic Enzymes: A Case Study from Central European Forests

Leaf litter decomposition is the key ecological process that determines the sustainability of managed forest ecosystems, however very few studies hitherto have investigated this process with respect to silvicultural management practices. The aims of the present study were to investigate the effects of forest management practices on leaf litter decomposition rates, nutrient dynamics (C, N, Mg, K, Ca, P) and the activity of ligninolytic enzymes. We approached these questions using a 473 day long litterbag experiment. We found that age-class beech and spruce forests (high forest management intensity) had significantly higher decomposition rates and nutrient release (most nutrients) than unmanaged deciduous forest reserves (P<0.05). The site with near-to-nature forest management (low forest management intensity) exhibited no significant differences in litter decomposition rate, C release, lignin decomposition, and C/N, lignin/N and ligninolytic enzyme patterns compared to the unmanaged deciduous forest reserves, but most nutrient dynamics examined in this study were significantly faster under such near-to-nature forest management practices. Analyzing the activities of ligninolytic enzymes provided evidence that different forest system management practices affect litter decomposition by changing microbial enzyme activities, at least over the investigated time frame of 473 days (laccase, P<0.0001; manganese peroxidase (MnP), P = 0.0260). Our results also indicate that lignin decomposition is the rate limiting step in leaf litter decomposition and that MnP is one of the key oxidative enzymes of litter degradation. We demonstrate here that forest system management practices can significantly affect important ecological processes and services such as decomposition and nutrient cycling.     

Nitrogen Translocation to Fresh Litter in Northern Hardwood Forest

Nitrogen immobilization in fresh litter represents a significant N flux in forest ecosystems, and changes in this process resulting from atmospheric N deposition could have important implications for ecosystem responses. We conducted two leaf decay experiments, using ¹⁵N-labeled sugar maple leaf litter, to quantify N transport from old litter and soil to fresh litter during early stages of decomposition, and we examined the influence of litter N concentration and soil N availability on upward N transfer in a northern hardwood forest. After one year of decay, the average N transfer from soil to fresh litter (2.63 mg N g^?1 litter) was much higher than the N transfer from older litter (1- to 2-years-old) to fresh litter (0.37 mg N g^?1 litter). We calculated the ratio of annual N transfer per unit of excess ¹⁵N pool for these two N sources. The ratio was not significantly different between old litter and soil, suggesting that fungi utilize N in the old litter and mineral soil pools for transport to decaying fresh litter with similar efficiency. Initial litter N concentration had a significant effect on upward N flux into decaying leaf litter, whereas no effect of soil N fertilization was observed. Reduction in the flux from soil to fresh litter owing to anthropogenic N inputs probably contributes significantly to changing soil N dynamics. Future work is needed on fungal N acquisition and transport as well as the fungal taxa involved in this process and their responses to changing environments.