Microorganisms surviving for 5300 years

Abstract Recently, the well-preserved corpse of a prehistoric man with an age of approximately 5300 years bp was discovered in the Central European Alps. Analysis of materials associated with the individual has revealed the presence of microorganisms which are believed to have survived since the time of death. So far, two fungi have been isolated and identified as species of the genera Chaetomium and Absidia , respectively. In addition, we have obtained one bacterial isolate which we have identified as a Streptomyces species. Our findings demonstrate that microorganisms can remain viable under appropriate circumstances for thousands of years. The isolates may enable us to study evolutionary trends within microorganisms.     

Has the prehistoric ice-man contributed to the preservation of living fungal spores?

Abstract There are arguments against the conclusion drawn by Haselwandter and Ebner that fungal spores have survived for some 5300 years on hay padding in the leather boots of frozen body discovered in the Austrian Alps. According to cryobiological experience, long-term survival of fungal spores is very unlikely at temperatures fluctuating between zero and −40°C. It is quite possible that living spores of these common species have recently reached this substratum.     

微生物菌剂对楸树幼苗生长及根际土细菌群落结构的影响

为探究球毛壳ND35微生物菌剂对楸树幼苗生长及土壤肥力的作用机制，本研究楸树幼苗为研究对象，采用室内盆栽试验，设计0（CK），10（T1），15（T2），20（T3）4种微生物菌剂施用量，测定幼苗生长情况、土壤微生物组成结构、土壤酶和土壤养分等特征。研究结果如下：（1）球毛壳ND35微生物菌剂可显著促进楸树幼苗的生长，株高、地径、地上及地下生物量显著提高（P<0.05），T2处理下促生效果最好。（2）施用球毛壳ND35微生物菌剂可显著提高土壤中有机质、硝态氮、铵态氮含量及脲酶、磷酸酶、蔗糖酶活性（P<0.05）。（3）球毛壳ND35微生物菌剂可显著影响土壤细菌群落组成，提高细菌群落的丰富度和多样性，使土壤中β-变形菌纲（Betaproteobacteria）、γ-变形菌纲（Gammaproteobacteria）的相对丰度显著下降，α-变形菌纲（Alphaproteobacteria）、δ-变形菌纲（Deltaproteobacteria）的相对丰度呈显著提高，可使土壤中鞘氨醇单胞菌属（Sphingomonas）的相对丰度显著提高21.88%-103.56%（P<0.05），芽孢杆菌属（Bacillus）的相对丰度提高66.28%-65.97%（P<0.05），酸杆菌属（Acidibacter）的相对丰度提高12.76%-38.06%。（4）冗余分析（RDA）结果表明，土壤硝态氮、铵态氮、有机质是影响土壤细菌群落分布和多样性的重要环境因子，土壤细菌群落结构的改变会显著影响土壤脲酶、蔗糖酶、碱性磷酸酶的活性。因此，施用球毛壳ND35微生物菌剂可通过影响植物根际土壤的化学性质及生物性质，促进楸树幼苗的生长。这一研究结果为楸树繁育提供了新的指导方向，亦为将其用于困难立地及退化生态系统植被恢复提供基础理论指导。     

Mycoparasitism of Rhizoctonia solani by Endophytic Chaetomium spirale ND35: Ultrastructure and Cytochemistry of the Interaction

The interaction between endophytic biocontrol agent Chaetomium spirale ND35 and the soil‐borne plant pathogen Rhizoctonia solani was studied by light microscopy and transmission electron microscopy (TEM), as well as further investigated by gold cytochemistry to assess the potential role of cell wall degrading enzymes (CWDEs) during the mycoparasitic process. Macroscopic observations of fungal growth in dual cultures revealed that pathogen growth inhibition occurred soon after contact with the antagonist, followed by the overgrowth of C. spirale on the colony of R. solani. The coiling of C. spirale around R. solani and intracellular growth of the antagonist in its host occurred frequently. Moreover, in advanced stage of interaction between the antagonist and the pathogen, The growth and development of C. spirale were associated with highly morphological changes of the host fungal cell, characterized by retraction of plasma membrane and cytoplasm disorganization. Further, TEM investigations through localization by gold immunocytochemistry showed that contact between the two fungi was mediated by an amorphous β‐1,3‐glucan‐enriched matrix originating from cell wall of the antagonist C. spirale and sticking to its host surface. At the same time, the hemispherical wall appositions which were intensely labeled by the antibodies of β‐1, 3‐glucan in cell wall of R. solani were induced to form at sites of potential antagonist entry. However, the antagonist was capable of penetrating this barrier, indicating that β‐1,3‐glucanases were produced during the mycoparasitic process. Localization of N‐acetylglucosamine residues (chitin) with the gold‐labelled wheat germ agglutinin (WGA) implicated that chitinases might be involved in the CWD of R. solani in this antagonistic process as well. This report is the first evidence about mechanisms of the interactions between C. spirale and R. solani in ultrastructural and cytochemical aspects.     

球毛壳菌组蛋白H3基因克隆与特性分析

构建了球毛壳菌菌丝的cDNA文库,并获得了1410条ESTs序列,用里氏木霉(Hypocrea jecorina,AAM76068)和粗糙脉胞菌(Neurospora crassa,CAA25761)的组蛋白H3基因(Histone H3)蛋白序列对球毛壳菌(Chaetomium globosum)ESTs序列本地数据库进行tBlastn检索,获得了球毛壳菌组蛋白H3cDNA序列。cDNA序列全长739bp,开放阅读框411bp,编码136个氨基酸组成的多肽,蛋白分子量为15.4kD。BlastP同源性分析表明该基因与里氏木霉同源性最高为100%;与地钱(Marchantia polymorpha)同源性最低为95%。三级结构预测表明,该蛋白C端为球状结构域,而N端结构对其发挥调控作用起重要作用。该基因的cDNA序列及推测的氨基酸序列在GenBank登录(登录号分别为AY669068,AAT74576)。     

Germinability and fungal occurrence in seeds of Abies alba Mill. populations in southern Italy

Abstract

Germination tests were carried out on seeds from three Italian populations of Abies alba. Seed germinability was up to 38%. HgCl₂, NaClO and plant preservative mixture were used as seed‐sterilising agents. Despite chemical treatments, Papulaspora rubida and Chaetomium globosum were isolated. The possible role of these fungi in the physiology of silver fir seed germination process was discussed.     

Tailoring of recombinant FDH: effect of histidine tag location on solubility and catalytic properties of Chaetomium thermophilum formate dehydrogenase (CtFDH)

Abstract

Several protein expression systems can be used to get enzymes in required quantities and study their functions. Incorporating a polyhistidine tag is a beneficial way of getting various enzymes such as FDHs for industrial applications. The NAD⁺ dependent formate dehydrogenase from Chaetomium thermophilum (CtFDH) can be utilized for interconversion of formate to carbon dioxide coupled with the conversion of NAD⁺ to NADH. In this study, N-terminal His tagged CtFDH (N-CtFDH) and C-terminal His tagged CtFDH (C-CtFDH) was constructed to learn the effect of His tag location on the activity and kinetic parameters of the enzyme. The solubility of proteins was not affected by tag position, however, an interference on the N-terminal region caused a deterioration in specific activity and the kinetic ability of enzyme. The obtained results indicated that the C-terminus of the enzyme is an appropriate region for tag engineering. The C-CtFDH has an approximately three-fold larger specific activity and two-fold higher catalytic efficiency than N-CtFDH. The results suggest that insertion of a His-tag at the N-terminal or C-terminal end of CtFDH has different effects on the protein and the N-terminal fragment of the protein is crucial for the function of CtFDH.     

Aureonitols A and B,Two New C13‐Polyketides from Chaetomium globosum,an Endophytic Fungus in Salvia miltiorrhiza

Two new C₁₃‐polyketides, aureonitols A and B ( 1 and 2 ), along with five known compounds ( 3 – 7 ), were isolated from the solid fermentation culture of the plant endophytic fungus Chaetomium globosum from the aerial parts of Salvia miltiorrhiza. The structures and absolute configurations of 1 and 2 were determined by comprehensive spectroscopic data analysis and computed methods. Compound 5 was found to display the remarkable antimicrobial activities against four multidrug‐resistant bacteria (Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, and Staphylococcus epidermidis) with MIC values of 3.13–6.25 μg/mL (ciprofloxacin: 0.78–1.56 μg/mL), and also against all tested fungal strains with MIC values of 3.13–25 μg/mL (ketoconazole: 0.78–12.50 μg/mL).     

Interaction network of the ribosome assembly machinery from a eukaryotic thermophile

Ribosome biogenesis in eukaryotic cells is a highly dynamic and complex process innately linked to cell proliferation. The assembly of ribosomes is driven by a myriad of biogenesis factors that shape pre‐ribosomal particles by processing and folding the ribosomal RNA and incorporating ribosomal proteins. Biochemical approaches allowed the isolation and characterization of pre‐ribosomal particles from Saccharomyces cerevisiae, which lead to a spatiotemporal map of biogenesis intermediates along the path from the nucleolus to the cytoplasm. Here, we cloned almost the entire set (～180) of ribosome biogenesis factors from the thermophilic fungus Chaetomium thermophilum in order to perform an in‐depth analysis of their protein–protein interaction network as well as exploring the suitability of these thermostable proteins for structural studies. First, we performed a systematic screen, testing about 80 factors for crystallization and structure determination. Next, we performed a yeast 2‐hybrid analysis and tested about 32,000 binary combinations, which identified more than 1000 protein–protein contacts between the thermophilic ribosome assembly factors. To exemplary verify several of these interactions, we performed biochemical reconstitution with the focus on the interaction network between 90S pre‐ribosome factors forming the ctUTP‐A and ctUTP‐B modules, and the Brix‐domain containing assembly factors of the pre‐60S subunit. Our work provides a rich resource for biochemical reconstitution and structural analyses of the conserved ribosome assembly machinery from a eukaryotic thermophile.     

川乌植物内生真菌抗菌活性的研究

从川乌（Radix aconiti）植物的根和茎中分离获得内生真菌61株,经显微形态观察进行内生真菌的分类鉴定,同时采用纸片法进行抗菌活性筛选。结果有29株内生真菌显示抗菌活性,占菌株数的47．54％;毛壳菌属是抗菌活性菌株的优势种属;活性高且抗菌谱广的菌株有3株,主要分布在毛壳菌属和束丝菌属。结果表明：川乌植物内生真菌中广泛分布着有抗菌活性的菌株。