矿质元素对毛头鬼伞菌丝体生长的影响

研究了4种矿质元素对栽培食用菌毛头鬼伞菌丝体生长的影响。4种矿质单元素添加试验结果表明,能使毛头鬼伞菌丝体旺盛生长的最佳浓度分别是CaCl20.1 mmol/L、MgSO48 mmol/L、KCl 1.22 mmol/L、NaH2PO413 mmol/L。4种元素协同作用试验结果表明,单元素浓度的最佳生长量与混合施用时的最佳生长量一致。以毛头鬼伞的主要栽培料之一的棉子壳估算,原料中的4种矿质元素浓度均偏低,必须补充矿质元素才能满足毛头鬼伞菌丝体的旺盛生长。     

毛头鬼伞的生物活性作用

毛头鬼伞具有高蛋白、低脂肪等优良特性。毛头鬼伞中含有20种氨基酸,其中人体必需的8种氨基酸全部具备;毛头鬼伞还含有钾、钠、钙、镁、磷等元素和铁、铜、锰、锌、钼、钴等微量元素。目前,毛头鬼伞已被定为符合联合国粮农组织(FAO)和世界卫生组织(WHO)要求的,集天然、营养、保健三种功能为一体的16种珍稀食用菌之一。迄今为止,有关毛头鬼伞生物活性作用的研究还开展得很不充分,国内有少量相关报道,国外对此研究甚少。本文对毛头鬼伞的生物学作用研究现状进行综述,为临床治疗肿瘤、糖尿病、感染性疾病等提供参考。     

富硒发酵毛头鬼伞菌丝对四氧嘧啶致糖尿病小鼠抗氧化和降血糖的影响

本文研究了富硒发酵毛头鬼伞(鸡腿菇)Coprinus comatus菌丝体对四氧嘧啶致糖尿病小鼠抗氧化和降血糖的影响。四氧嘧啶建立糖尿病小鼠模型后,将富硒发酵毛头鬼伞菌丝均匀混入饲料中,由小鼠自由取食进行治疗,3周后观察富硒毛头鬼伞菌丝对糖尿病小鼠血糖、MDA、SOD和GSH-Px的影响。结果发现,采用富硒发酵毛头鬼伞菌丝进行治疗后,糖尿病小鼠血糖明显降低;血清和组织中MDA含量显著下降;血清和组织中的SOD和GSH-Px的活力明显的增加。由此推断,富硒发酵毛头鬼伞菌丝对四氧嘧啶致糖尿病小鼠的降血糖效果可能是通过提高机体抗氧化能力来实现的。     

毛头鬼伞多糖对烟草酶活性和同工酶谱的影响

分析了毛头鬼伞(Coprinus comatus)真菌多糖诱导烟草对烟草花叶病毒(TMV)抗性过氧化物酶(POD)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、几丁质酶、-β1,3-葡聚糖酶活性的变化。结果表明,毛头鬼伞多糖可提高POD、PPO、PAL、几丁质酶和-β1,3-葡聚糖酶的活性,接种TMV后毛头鬼伞多糖处理的烟草酶活性显著高于不处理者。上述结果提示,毛头鬼伞多糖处理后烟草酶活性的增强可能与其诱导烟草获得抗性有关。     

毛头鬼伞(Coprinus comatus)多糖的理化性质及体外抗氧化活性

毛头鬼伞(Coprinus comatus)子实体经热水浸提、乙醇沉淀、脱蛋白和真空干燥后得到毛头鬼伞多糖。经定性化学反应和光谱鉴定,毛头鬼伞多糖不含蛋白质、核酸、酚类物质和糖醛酸,为非淀粉类中性多糖,均分子量为947 kD,完全酸水解后经气相色谱分析确定其糖基组成及其摩尔组成比为葡萄糖∶甘露糖∶半乳糖=10.5∶1.7∶1。通过对脱氧核糖体系产生的羟基自由基(.OH)的清除作用和邻苯三酚自氧化系统产生的超氧阴离子自由基(O2-.)的清除作用,对毛头鬼伞多糖体外抗氧化活性进行的研究结果表明:该多糖具有一定的抗氧化活性。     

解淀粉芽孢杆菌MN-8对玉米秸秆木质纤维素的降解

微生物降解木质纤维素既是生物质资源化利用中的关键问题,也是亟需解决的难点问题.本文在前期获得木质素降解菌——解淀粉芽孢杆菌MN-8菌株的基础上,进一步研究该菌株对玉米秸秆木质纤维素的降解作用.研究利用玉米秸秆粉-MSM培养基对MN-8菌株进行固态发酵,监测发酵过程中木质纤维素酶活力和木质纤维素含量变化情况,并通过傅立叶红外光谱(FTIR)和气质联用色谱(GC/MS)对木质纤维素的降解情况及产物进行分析.结果表明:解淀粉芽孢杆菌MN-8菌株可产生木质素过氧化物酶、锰过氧化物酶、纤维素酶和半纤维素酶等木质纤维素降解酶,在发酵10～16 d陆续达到酶活力峰值,最高酶活力分别为55.0、16.7、45.4和60.5 U·g-1.发酵24 d后,玉米秸秆中木质素、纤维素和半纤维素的降解率可分别达到42.9％、40.6％和27.1％.FTIR光谱数据表明,玉米秸秆发酵后木质素、纤维素和半纤维素的特征吸收峰强度均有一定程度的下降,表明木质纤维素被部分降解.GC/MS分析结果也证实,解淀粉芽孢杆菌MN-8能有效降解秸秆木质纤维素.MN-8菌株可断裂玉米秸秆木质素单体之间的连接键β-O-4,将秸秆木质素解聚为苯丙胺、苯丙酮和苯丙酸等保留木质素苯丙烷结构的单体化合物,并将部分单体化合物进一步氧化为Cα羰基化合物,如2-氨基-1-苯丙酮和紫丁香基苯乙酮等.在对纤维素和半纤维素降解产物的GC/MS分析中发现,降解产物包含葡萄糖、甘露糖和半乳糖等多种单糖化合物以及甲酸、乙酸、丙酸、1,1-乙二醇和3-羟基丁酸等代谢产物.表明解淀粉芽孢杆菌MN-8对秸秆木质纤维素表现出强降解作用,且该作用依赖于菌株产木质纤维素降解酶的能力.     

57株毛头鬼伞遗传多样性分析

运用SRAP、RAPD、ISSR3种分子标记技术对来源不同地区的57株毛头鬼伞Coprinus comatus进行了遗传多样性分析,通过3种分子标记进行聚类分析,当相异系数D为0.48时,可以把57株毛头鬼伞分为4类:Ⅰ类包括Co0001;Ⅱ类包括Co0003;Ⅲ类包括Co0005;Ⅳ类包括其余54个菌种。供试的57个菌株间的相异系数范围从0–0.72,具有一定的遗传多态性。但其中有许多菌株两者之间的相异系数为0,说明毛头鬼伞菌种存在着比较严重的同种异名现象。     

绒毛栓孔菌液体培养过程中胞外酶活性的研究

本研究以绒毛栓孔菌为材料,采用液体培养的方法分析其在发酵过程中胞外酶的活性变化,并对其菌丝体生物量和发酵液pH值进行了测定。结果表明:胞外酶活性与菌丝体生长状况密切相关。菌丝体生物量增长呈"S"型,6～8d增长最快,第12天达到最大值,在此过程中漆酶、锰过氧化物酶、淀粉酶、羧甲基纤维素酶、果胶酶和蛋白酶活性均出现高峰。酶活性的变化表明,在液体培养过程中绒毛栓孔菌首先分解木质素,其次利用淀粉和纤维素作为碳源,蛋白质作为氮源。若要获得最大菌丝体生物量,缩短培养时间,就必须在培养过程中保证碳氮源的均衡供给。本试验说明不同的酶其分泌高峰期可以作为判断菌丝体营养利用情况和培养周期的依据,以此获取最大菌丝体生物量,为工业生产利用奠定基础。     

香菇基因型及对蔗渣降解水平的研究

在江南一些地方采集九株野生香菇,分析担孢子基因型并测定A、B不亲和因子等位基因的数目及差异,保藏以A_xB_x(或A-yB_y)标记的单核菌丝体。实验结果表明,每一菌株的四个基因型呈随机分配。香菇A·B因子具有地区性,重复频率很低,等位基因差异明显。九个菌株的单核菌丝体的基因型从A_1B_1到A_(18)B_(18)不同。进一步对14个菌株(包括上述野生菌株)在蔗渣培养基上生长70天后对主要基质降解程度的测定表明,除个别菌株比较适合用蔗渣进行栽培外,其它菌株对蔗渣中纤维素、半纤维素和木质素的分解利用能力都较差。     

灰树花gpd-Gf启动子的功能分析

利用从灰树花菌丝体中克隆的gpd-Gf（615bp）启动子片段串联于报告基因gfp上游,构建启动子功能活性检测表达质粒pGg-gfp。采用PEG介导法把表达质粒pGg-gfp与辅助质粒pCc1001（含有trp1基因）共转化进色氨酸营养缺陷型的灰盖鬼伞粉孢子的原生质体中。经过选择培养基筛选、假定转化子的分子鉴定以及GFP荧光检测, 结果表明：灰树花gpd-Gf启动子在灰盖鬼伞菌丝中具有较强驱动gfp基因表达的活性,在荧光显微镜和共聚焦显微镜下可以观察到转化子菌丝发出的强烈荧光。     

欧洲黑杨基因资源材性关联基因的SNP分析

以115个欧洲黑杨(Populus nigra L.)无性系为材料, 利用TaqMan技术分析了欧洲黑杨基因资源参与木质素和纤维素合成的酶(4CL、PAL和CesA2)的单核苷酸多态性, 并对分型的SNPs与木材材性性状(物理性状：基本密度、纤维长、纤维宽、微纤丝角; 化学性状: 木质素含量、纤维素含量、a 纤维素含量等)进行了相关分析。结果如下: (1)在对4CL、PAL和CesA2等3个基因进行检测时, 共获得27个SNPs标记, 对其中转换(A-G, C-T)有17个位点, 颠换(A-C, G-C, G-T, A-T等)有10个位点; (2)对其中的3个SNPs进行了分型, 分别记作SNP1、SNP2和SNP3; (2)对已经分型SNPs位点与材性性状进行方差分析, 结果显示, 3个SNPs中只有SNP1与4年生欧洲黑杨综纤维素含量显著相关, 表现为负效应, 贡献率为11.11%; (3)对欧洲黑杨4CL基因的SNP1标记的不同基因型所对应的材性性状进行方差分析, 结果显示基因型为CC和CT的欧洲黑杨相对于基因型为TT的欧洲黑杨有较高的纤维素含量。     

Fungal succession and decomposition of <Emphasis Type="Italic">Camellia japonica</Emphasis> leaf litter

Decomposition processes of Camellia japonica leaf litter were investigated over an 18-month period with reference to the role of fungal succession in the decomposition of lignin and holocellulose. Decomposition and fungal succession were studied in bleached and nonbleached portions of litter, which were precolonized by ligninolytic and cellulolytic fungi, respectively. Coccomyces nipponicum and Lophodermium sp. (Rhytismataceae), which can attack lignin selectively, caused mass loss of lignin and were responsible for bleaching during the first 4 months (stage I), whereas cellulolytic fungi caused mass loss of holocellulose in adjacent nonbleached portions. Soluble carbohydrates and polyphenols also decreased rapidly during this stage. Pestalotiopsis guepini, coelomycete sp.1, and the Nigrospora state of Khuskia oryzae caused mass loss of holocellulose between 4 and 14 months (stage II) and Xylaria sp. caused mass loss of both lignin and holocellulose from 14–18 months (stage III). In stages II and III, decomposition was more rapid in bleached portions than in nonbleached portions probably due to the prior delignification of lignified holocellulose in bleached portions. Frequencies of these fungi showed different responses among species to the pattern of changes in lignin and holocellulose contents during decomposition. Total hyphal length increased in both portions over the study period, but mycelia of basidiomycetes accounted for about 2% of total hyphal length, suggesting that their role in fungal succession and decomposition was low. Lignin and nitrogen contents were consistently lower and holocellulose content was higher in bleached portions than in nonbleached portions during decomposition. The succession of ligninolytic and cellulolytic fungi was a major driving factor that promoted decomposition and precolonization by ligninolytic fungi enhanced decomposition.     

Bioconversion of wheat straw and wheat straw components into single-cell protein.

Several fungi (Aspergillus niger, A. terreus, Cochliobolus specifer, Myrothecium verrucaria, Rhizoctonia solani, Spicaria fusispora, Penicillium sp., and Gliocladium sp.) were isolated from decomposing wheat straw and tested for their ability to utilize whole straw and its components, holocellulose (hemicellulose and cellulose) and cellulose, for the production of single-cell protein (SCP). It was found that C. specifer was the most efficient fungus for protein synthesis with the three substrates. Using potassium nitrate as N source in mixtures of 0.04 g N/g substrate (0.04% wt./vol.) at pH 4.5, it was found that incubation periods of 3, 4, and 5 days were optimal for protein production on cellulose and holocellulose fractions, and whole straw, respectively. Whole native straw was found to be the most recalcitrant to bioconversion into SCP; however, protein production was almost doubled when the lignin component was removed using a mixture of sodium chlorite and acetic acid.     

Litter decomposition of three lignin-deficient mutants of Sorghum bicolor during spring thaw

Decomposition of plant litter during the freeze-thaw season has recently gained attention as having a significant role in nutrient cycling in many cold ecosystems. However, few studies have examined decomposition of crop remnants during the freeze-thaw season in an agronomic setting when microbial activity is presumably low. We examined decomposition of four cultivars of sorghum (Sorghum bicolor) leaves in a field in Southern Minnesota, USA using the litterbag method. Three of the four cultivars we examined expressed the brown midrib (bmr) mutation which have altered/reduced levels of lignin in their secondary cell walls compared to the wild-type (WT). Litter was buried in the fall and harvested during the spring thaw. After 160 d the bmr mutants lost 57–62% of their initial mass, compared to 51% in the WT. Mass loss agreed with presumed initial litter quality, as the bmr litter had higher initial N, and holocellulose:lignin and lower lignin, C:N and lignin:N values compared to the WT. The increased decomposition of the bmr cultivars appears to be related to increased loss of hemicellulose and holocellulose (cellulose+hemicellulose) or higher initial N concentrations. Alterations in cell-wall deposition in the bmr cultivars may increase accessibility of microbial cell-wall degrading enzymes that accelerate mass loss. Our results demonstrate that alterations in initial lignin chemistry may influence decomposition of sorghum litter in an agronomic setting.     

里氏木霉和鸡腿菇利用秸秆共发酵产木质降解酶

为了更好地利用农业废弃物,提高其综合利用率,减少传统化学方法及秸秆焚烧过程造成的环境污染,实验对鸡腿菇、黑曲霉和里氏木霉3株产木质纤维素降解酶系的菌株进行混合平板产酶筛选,结果显示鸡腿菇和里氏木霉平板培养相容性良好,且产酶量高。在相容性实验的基础上,对鸡腿菇和里氏木霉的最优产酶条件进行了研究。在最优条件下:鸡腿菇和里氏木霉接种比例按5:2,接种时间间隔为12h,26oC、150r/min下,发酵3d产漆酶活力达3267.2U/mL,比单独发酵提高106%。     

Organosolv pulping of wheat straw by use of phenol

A central composite design was used to investigate the influence of the cooking conditions (time, temperature and phenol concentration) for wheat straw with phenol-water mixtures on the properties of the pulp obtained (yield and holocellulose, -cellulose, lignin and ethanol-benzene extractable contents) and the pH of the resulting wastewater. A second-order polynomial model consisting of three independent process variables was found to accurately describe the organosolv pulping of wheat straw. The equations derived predict the yield, the holocellulose, -cellulose, lignin and ethanol-benzene extractable contents of the pulp, and the pH of the wastewater with multiple-R, R² and adjusted-R² high values. The process variables must be set at low variables in order to ensure a high yield and pH. Conversely, if high holocellulose and -cellulose contents, and low lignin and ethanol-benzene extractable contents are desired, then a high temperature (200°C), long cooking time (120 min), and intermediate phenol concentration (65%) must be used.     

大贵寺国家森林公园野生青檀檀皮纤维成分分析

分析了湖北大贵寺国家森林公园野生青檀种群64份2～3年生青檀枝条檀皮的纤维成分.结果表明,该野生青檀枝条檀皮纤维的水分、灰分、冷水抽出物、热水抽出物等指标的平均值分别为8.267％、6.273％、24.025％、26.594％;1％NaOH抽出物、苯-醇抽出物、综纤维素、酸不溶木素等指标的平均值分别为60.904％、11.011％、56.759％、9.698％;纤维素吸光值为0.373.酸不溶木素、灰分、纤维素吸光值以及1％ NaOH抽出物4个指标呈现近正态分布,其它指标的分布偏斜度较大;水分与1％ NaOH抽出物、灰分与酸不溶木素、综纤维素与酸不溶木素之间具有显著的相关性(p＜0.05);水分与灰分、水分与热水抽出物、水分与综纤维素、苯-醇抽出物与综纤维素、苯-醇抽出物与酸不溶木素之间具有极显著的相关性(p＜0.01).平均连锁值取5.627时,可以把64个样品分为23类,说明大贵寺国家森林公园野生青檀群体檀皮纤维成分存在着较高的表型多样性,具有广阔的遗传改良前景.     

Influence of biochemical quality on C and N mineralisation from a broad variety of plant materials in soil

We studied C and N mineralisation patterns from a large number of plant materials (76 samples, covering 37 species and several plant parts), and quantified how these patterns related to biological origin and selected indicators of chemical composition. We determined C and N contents of whole plant material, in water soluble material and in fractions (neutral detergent soluble material, cellulose, hemicellulose and lignin) obtained by stepwise chemical digestion (modified van Soest method). Plant materials were incubated in a sandy soil under standardised conditions (15 °C, optimal water content, no N limitation) for 217days, and CO₂ evolution and soil mineral N contents were monitored regularly. The chemical composition of the plant materials was very diverse, as indicated by total N ranging from 2 to 59 mg N g^–1, (i.e. C/N-ratios between 7 and 227). Few materials were lignified (median lignin=4% of total C). A large proportion of plant N was found in the neutral detergent soluble (NDS) fraction (average 84%) but less of the plant C (average 46%). Over the entire incubation period, holocellulose C content was the single factor that best explained the variability of C mineralisation (r=–0.73 to –0.82). Overall, lignin C explained only a small proportion of the variability in C mineralisation (r=–0.44 to –0.51), but the higher the lignin content, the narrower the range of cumulative C mineralisation. Initial net N mineralisation rate was most closely correlated (r=0.76) to water soluble N content of the plant materials, but from Day 22, net N mineralisation was most closely correlated to total plant N and NDS-N contents (r varied between 0.90 and 0.94). The NDS-N content could thus be used to roughly categorise the net N mineralisation patterns into (i) sustained net N immobilisation for several months; (ii) initial net N immobilisation, followed by some re-mineralisation; and (iii) initially rapid and substantial net N mineralisation. Contrary to other studies, we did not find plant residue C/N or lignin/N-ratio to be closely correlated to decomposition and N mineralisation.