Species richness and species composition of fungal communities associated with cellulose decomposition at different altitudes on the Tibetan Plateau

Aims The aims of this study were to compare the fungal communities developing on cotton strips at three different altitudes on the Tibetan Plateau and to assess the environmental variables influencing them.Methods Cotton strips that had been buried in soil for a year were sampled at three sites at different altitudes (4500, 4950 and 5200 m) located on a southeast-facing slope on the Nyainqentanglha Mountains near Damxung. The fungi on the cotton strips were isolated using a modified washing method. The decomposition abilities and colony growth properties of the major species cultured in pure-culture conditions were investigated and compared. Canonical correspondence analysis (CCA) was used to evaluate the relationships between fungal community composition and environmental variables (altitude, soil depth, soil water content [SWC], plant root mass and gravel content).Important findings A total of 24 species were isolated from the cotton strips, and 12 species occurred frequently and were regarded as major species. The number of fungal species was lower at the 4950-m altitude site than at the other two sites, indicating that not only altitude but also other factors affected the number of species present. All of the major species were able to decompose the cotton strips. In the CCA ordination, automatic forward selection revealed that altitude, SWC and plant root mass significantly affected fungal species composition. Our results suggest that species number and the composition of cellulolytic fungal communities are highly correlated with environmental variables as well as altitude in the alpine meadow on the Tibetan Plateau.     

Fungal communities associated with degradation of polyester polyurethane in soil

Soil fungal communities involved in the biodegradation of polyester polyurethane (PU) were investigated. PU coupons were buried in two sandy loam soils with different levels of organic carbon: one was acidic (pH 5.5), and the other was more neutral (pH 6.7). After 5 months of burial, the fungal communities on the surface of the PU were compared with the native soil communities using culture-based and molecular techniques. Putative PU-degrading fungi were common in both soils, as <45% of the fungal colonies cleared the colloidal PU dispersion Impranil on solid medium. Denaturing gradient gel electrophoresis showed that fungal communities on the PU were less diverse than in the soil, and only a few species in the PU communities were detectable in the soil, indicating that only a small subset of the soil fungal communities colonized the PU. Soil type influenced the composition of the PU fungal communities. Geomyces pannorum and a Phoma sp. were the dominant species recovered by culturing from the PU buried in the acidic and neutral soils, respectively. Both fungi degraded Impranil and represented >80% of cultivable colonies from each plastic. However, PU was highly susceptible to degradation in both soils, losing up to 95% of its tensile strength. Therefore, different fungi are associated with PU degradation in different soils but the physical process is independent of soil type.     

Fungal Communities Associated with Degradation of Polyester Polyurethane in Soil

Soil fungal communities involved in the biodegradation of polyester polyurethane (PU) were investigated. PU coupons were buried in two sandy loam soils with different levels of organic carbon: one was acidic (pH 5.5), and the other was more neutral (pH 6.7). After 5 months of burial, the fungal communities on the surface of the PU were compared with the native soil communities using culture-based and molecular techniques. Putative PU-degrading fungi were common in both soils, as <45% of the fungal colonies cleared the colloidal PU dispersion Impranil on solid medium. Denaturing gradient gel electrophoresis showed that fungal communities on the PU were less diverse than in the soil, and only a few species in the PU communities were detectable in the soil, indicating that only a small subset of the soil fungal communities colonized the PU. Soil type influenced the composition of the PU fungal communities. Geomyces pannorum and a Phoma sp. were the dominant species recovered by culturing from the PU buried in the acidic and neutral soils, respectively. Both fungi degraded Impranil and represented >80% of cultivable colonies from each plastic. However, PU was highly susceptible to degradation in both soils, losing up to 95% of its tensile strength. Therefore, different fungi are associated with PU degradation in different soils but the physical process is independent of soil type.     

A rapid method for assessing the resistance of polyurethanes to biodeterioration

A rapid soil burial method for assessing the susceptibility of polyurethanes to biodeterioration was developed. The time of the test was reduced by prestressing the polyurethanes. The degree of deterioration was measured by following changes in the appearance of the polyurethanes and in selected physical properties. It was found that pre-stressing produced significant reductions in the tensile strength of a known susceptible polyurethane after burial in soil for 2 weeks. The reduction was greater than that found with unstressed polyurethanes buried for 26 weeks in active soil. Changes in tensile strength were less after burial for 4 weeks in sterile soil than after burial in active soil for the same period. The results suggest that deterioration of polyurethane during soil burial is a result of both chemical and microbial action.     

Beiträge zur Anwendung der Bodenwaschtechnik für die Isolierung von Bodenpilzen

Zusammenfassung Zwei zeitsparende Modifikationen der Parkinson & Williams-Bodenwaschtechnik für die Isolierung von Pilzen auf Bodenpartikeln werden beschrieben. Das wesentliche Merkmal beider Modelle ist der kontinuierliche Wasserdurchfluß durch das Waschgefäß, das von Hand oder mechanisch geschüttelt werden kann.Die Wirksamkeit der Bodenwaschung in Abhängigkeit von der verwendeten Wassermenge wurde indirekt ermittelt durch Zählung des Sporengehalts im Waschwasser und durch Bestimmung des Kolonisationsquotienten für die gewaschenen Partikel. Wenn der Sporengehalt des Waschwassers auf ein bestimmtes niedriges Niveau abgesunken war, blieb auch der Kolonisationsquotient konstant, unabhängig von der verwendeten Technik.Die Isolierungsfrequenz der häufigsten Pilzarten in Bodenproben derselben Herkunft ließ sich zufriedenstellend reproduzieren. Jahreszeitliche Schwankungen in der Pilzflora auf gewaschenen Partikeln waren unbedeutend. Die Anzahl der Pilze auf Bodenpartikeln nahm mit der Bodentiefe stark ab.Mehr Arten wurden von gewaschenen Partikeln isoliert als aus dem Waschwasser derselben Bodenprobe. Einige Arten, wie Fusarium culmorum, F. avenaceum, F. equiseti, Mucor hiemalis, Ophiobolus graminis, wurden häufiger von organischen als von Mineralpartikeln isoliert; dagegen ließ sich in der Verteilung der meisten von ca. 300 weiteren Arten kein signifikanter Unterschied für die Partikelarten nachweisen. Nur wenige sehr langsamwüchsige Arten wurden ausschließlich von Mineralpartikeln isoliert.

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Contributions to the soil washing technique for the isolation of soil fungi

Summary Two time-saving modifications of the Parkinson and Williams soil washing technique for the isolation of fungi from soil particles are described. The characteristic feature of both modifications is the continuous flow of water through the washing boxes, which can be shaken by hand or mechanically during the washing procedure.The effectiveness of the soil washing depending on the amount of water used was tested indirectly by counting the spore content of the washing water and by determining the colonisation ratio of the washed particles. When the spore content of the washing water had dropped to a certain low level, the number of fungi per washed particle was found to be constant, independently from the technique used.The isolation frequency of the most abundant fungal species in soil samples of the same origin could be reproduced satisfactorily. Seasonal variations in the fungal lora of washed particles were insignificant. The number of fungi colonizing soil particles decreased strongly with soil depth.More species were isolated from washed particles than from dilution plates poured with the washing water of the same soil sample. Some species, e.g. Fusarium culmorum, F. avenaceum, F. equiseti, Mucor hiemalis, Ophiobolus graminis, were more frequent colonizers of organic soil particles, whereas the distribution pattern of about 300 other species did not differ significantly on mineral or organic particles. Only a few very slow growing species were isolated exclusively from mineral particles.

     

湛江红树林滩涂可培养真菌种群多样性分析

【目的】明确湛江地区红树林滩涂海洋真菌的种类及其分布,为海洋真菌的开发利用研究奠定基础。【方法】运用稀释平板法从湛江市高桥及特呈岛红树林滩涂不同的潮位带(低、中、高)和不同树种(白骨壤、桐花树、木榄、红海榄)采集淤泥样品550份,采用真菌形态学和ITS序列分析技术进行多样性研究【。结果】分离获得海洋真菌274株,共鉴定出19属39种真菌,以曲霉属Aspergillus、青霉属Penicillium和木霉属Trichoderma真菌分离频率高,为湛江红树林滩涂优势真菌种类,尤其在中潮位带真菌种类最多。此外,分离获得真菌Talaromyces helicus,为中国新记录种。【结论】湛江红树林滩涂海洋真菌的种类十分丰富,具有潜在的开发和利用前景。     

Analysis and comparison of the microflora isolated from fresco surface and from surrounding air environment through molecular and biodegradative assays

The aim of this study was to find a correlation among the environmental isolated microflora and the fresco colonizators through the investigation of their biodegradative abilities and DNA characteristics. A molecular technique named RAMP (Random Amplified Microsatellite Polymorphisms) was utilized in order to analyze the DNA diversity of bacterial and fungal species isolated from fresco as well as from air samples. The RAMP-PCR results were combined with the screening of some biodegradative properties obtained through the use of specific agar plate assays detecting the proteolytic, solubilization and biomineralization abilities of the isolated microflora. This comparative analysis showed that only in few cases a direct link among the fresco and airborne isolates of specific microbial group existed. The investigation clearly evidenced that colonization of surface of Ladislav’s fresco occurred in different time and by different strains than those observed at the moment of sampling campaign. Furthermore, the microflora investigation permitted the identification of taxonomically interesting bacteria with particular biodegradative properties, which had been less studied until now.     

Ecological study of soil fungi of an agricultural field in Allahabad

Summary The soil fungi from an agricultural field in Allahabad where sugarcane is being grown for many years, have been isolated from various depths during different seasons and were identified. The inter-relations of chemical composition of soil and distribution of fungi is also being shown here.The techniques for the isolation and the study of the fungus flora was that ofGoddard modified bySaksena &Mehrotra. Soil samples were examined from 1–6 depths in three seasons of the year and were mechanically and chemically analysed.For the isolation, soil dilution plate method, a modification ofMenzies' method, direct method ofWaksman, Rossi Cholodny Burried slide technique, and screened immersion plate method, were followed Fifty five different species of microfungi belonging to Phycomycetes, Ascomycetes and Fungi — Imperfecti were isolated and identified. The moisture contents, hydrogen-ion concentrations, carbon, nitrogen, phosphorus, calcium, magnesium and iron, etc., of the soil samples from 1–6 inches depths, were also studied.Out of these 12 species covering 9 genera belonged to the Phycomycetes, nine genera of Ascomycetes and nine genera of Fungi Imperfecti were recorded.P. multicolor Grigorieva-Monoilova &Poradielova, andP. roqueforti Thom.,Gliocladium vermoesoni (Biourge)Thom. andMasoniella grisea (Smith)Smith were recorded for the first time from Indian Soil. A new varietyChaetominum nigricolor Ames var.simplex was also isolated.     

Synthetic dyes decolourisation by white-rot fungi: Development of original microtitre plate method and screening

A microtitre plate-based method was developed for a fast screening of numerous fungal strains for their ability to decolourise textile dyes. In 3 days, this method allowed to estimate significant fungal decolourisation capability by measuring the absorbance decrease on up to ten dyes. More than 325 white-rot fungi (WRF) strains belonging to 76 fungal genera were compared with regards to their capability to decolourise five azo and two anthraquinone dyes as well as the dyes mixture. The most recalcitrant dyes belonged to the azo group. Several new species unstudied in the bioremediation field were found to be able to efficiently decolourise all the dyes tested.     

Sensitivity of Malayan isolates of Fusarium to soil fungistasis

Summary Spore germination of various isolates of Fusarium (isolated from Malayan sources) was inhibited when placed on cellulose film in contact with soil moistened with distilled water. Intraspecific variations in sensitivity to mycostasis were recorded suggesting physiological differences between isolates of the same species. The addition of glucose frequently masked the mycostatic factor while autoclaving the soil completely removed it. The growth of fungal mycelium in contact with soil followed a similar pattern and when hyphae grew in contact with autoclaved soil sporulation was frequently observed.The similarities between the results outlined in this investigation and results from different countries is discussed and it is suggested that pathogenic fungi frequently have to overcome soil mycostasis before they can establish themselves in a new environment.     

Microfungi of a Danish Beech forest Microbiology of a Danish beech forest II

The fungal flora in different parts of a beech forest ecosystem was investigated through a four year period as part of an IBP project. Both colony counts and direct measurements of fungal mycelium indicated that a vast majority of the fungal biomass is concentrated in the upper horizons of the soil, especially in the mull layer. The litter also contained large amounts of fungi when calculated per g dry weight, but still the litter fungi accounted for only a quite small percentage of the total fungal biomass. The fungi growing in direct contact with the living plants, i.e. in the rhizosphere and phylloplane, also accounted for only a few per cent of the total amount of fungi in the ecosystem.
On basis of direct measurements of fungal mycelium the total biomass was estimated to be about 100 g dry wt per m². However, no attempts were made to distinguish between living and dead hyphae, and a large proportion of the observed hyphae may very well be dead or inactive.
Qualitative studies revealed that the upper soil layers not only contained the largest amounts of fungal mycelium, but also by far the highest species diversity. Other parts of the ecosystem, e.g. the phylloplane, were often strongly dominated by one or a few species, whereas soil always contained a large variety of different types.     

Spatiotemporal Patterns of Laccase Activity in Interacting Mycelia of Wood-Decaying Basidiomycete Fungi

Abstract Interspecific fungal interactions are important ecological processes, whereas their physiological mechanisms are little understood. The aim of this work was to study how activity of fungal extracellular laccase was changed across mycelia during interactions between white- and brown-rot basidiomycetes from different wood decay stages. Qualitative assay of eight species interacting with each other in all combinations showed four spatial patterns of laccase activity: (I) laccase activity present both in contact zone and mycelium, (II) laccase activity only in contact zone, (III) laccase activity in mycelium but not in contact zone, (IV) no laccase activity. Presence of laccase activity only in the contact zone was more frequent than expected from random samples associated with mycelia that replaced other ones. On the other hand, the presence of laccase activity in the mycelium but not in the contact zone was only attributed to fungal species that were replaced by their antagonists. After one month, laccase activity was distributed over mycelia more homogeneously than after 6 days of interactions. In interacting mycelia, laccase activity was higher than in control and increasing with time. Saprotrophic fungi from late successional stages of wood decay generally had higher laccase activity than early succession saprotrophic and pathogenic fungi. The qualitative assays were confirmed by quantitative assay of total laccase activity. Significance of the results in antagonistic fungal interactions as well as in the processes of hyphal tip growth and mycelium senescence is discussed. Received: 6 October 1999; Accepted: 1 February 2000; Online Publication: 5 May 2000     

Studies on pathogenic dematiaceous fungi

Two hundred and twenty-six samples of woody materials, vegetable matter and soil were processed by the direct plating and mouse inoculation technique for the isolation of pathogenic dematiaceous fungi. The species of fungi isolated were Fonsecaea pedrosoi — 13, Cladosporium carrionii — 7 and Phialophora verrucosa — 4 isolates. The mouse inoculation technique was found to be much better than direct plating for the recovery of these fungi. Woody plant materials proved to be a good sample source for pathogenic dematiaceous fungi contributing about 90% of the isolates. All the isolates were pathogenic for mice as evidenced by the presence of dark nodular lesions containing fungal elements in the organs of experimentally infected animals.     

辽宁碱蓬根际土壤真菌多样性的季节变化及其耐盐性

采用稀释平板法和形态学鉴定法进行了辽宁碱蓬(Suaeda liaotungensis)根际土壤真菌的分离鉴定及季节、盐度对真菌多样性的影响分析。结果表明:春、夏、秋、冬四季辽宁碱蓬根际土壤中的真菌菌落数分别为6410、4180、5730和3340,种类分别为6属13种、9属16种、11属31种、6属12种,共分离鉴定出13属42种真菌;其根际土壤真菌的多样性指数、丰富度指数和均匀度指数,从大到小的次序均为秋夏春冬,3种指数均在秋季达到峰值;多样性指数和丰富度指数差异较大,均匀度指数波动较小,春季和冬季的均匀度指数相近。辽宁碱蓬根际土壤真菌种类明显多于无植被土壤,是无植被土壤的7倍,多样性指数和均匀度指数分别是无植被土壤的4—8倍和1—1.2倍;其根际土壤真菌优势种群包括青霉属(Penicillium)、葡萄穗霉属(Stachybotrys)、枝孢属(Cladosporium)、木霉属(Trichoderma)、曲霉属(Aspergillus)和镰孢属(Fusarium);4个季节的优势菌不尽相同,但均有一个共同的优势菌属青霉属。以Na Cl浓度梯度法制造盐胁迫生境,检测辽宁碱蓬根际土壤真菌对盐胁迫的响应,结果表明:60%左右的菌种能耐受5%以下盐度、15%左右的菌种能耐10%—20%盐度;筛选出了6株高度耐盐菌:细交链孢霉、草酸青霉、产黄青霉、烟曲霉、细极链格孢和赭曲霉,其中最高耐盐菌种赭曲霉可耐20%盐度。创新之处在于以盐度和季节为变量检测辽宁碱蓬根际土壤真菌的种群构成,为其深入研究奠定了理论基础。     

Characterization of thermophilic Campylobacter. II. Enzymatic profiles

The enzymatic profiles of 234 wild strains of thermophilic Campylobacters, seven type strains ofCampylobacter species, and 18 reference strains ofCampylobacter species and Campylobacter-like organisms were studied by use of API strips. These strips allow the detection of 56 arylamidases, one transpeptidase, and ten esterases.Forty enzymes were present at least once. The mean number of enzymes per strain was 13. The enzymatic activity was usually weak. Three enzymes were present in all the strains: esterases of butyric and valeric acids, andl-phenylalanine-l-proline arylamidase. A combination of three enzymes provided a good predictive value for the species differentiation ofC. jejuni andC. coli. There were no differences in relation to the geographical origin of the strain nor to the animal species from which it was isolated. The -glutamyl transpeptidase could be used for the biotyping of the strains.A portion of this work was presented at the Second Workshop of Campylobacter Infections, held in Brussels, Belgium, in September 1983.     

Distribution of acetyl esterase in wood-rotting fungi

The distribution of acetyl esterase was studied in 30 strains of wood-rotting fungi. A screening test on agar plates using glucose β-d-pentaacetate as a substrate indicated that all tested fungi produced acetyl esterase to form a clear zone on the culture. All fungi also showed positive responses in an agar test using carboxymethyl cellulose acetate. Enzyme assay showed that extracellular acetylxylan esterase activity was present in the filtrates of wood-meal culture of all these fungi. The ratio of fungal acetylxylan esterase activity to 4-nitrophenyl acetyl esterase activity were higher than that of porcine liver esterase, indicating that fungal esterases have high affinity for acetylated carbohydrates. Acetyl esterase is suggested to be distributed widely in wood-rotting fungi for degradation of native acetylated hemicelluloses.     

Comparative study reveals unique features of the mycobiota in peat soils samples from Japan and Scotland

We isolated filamentous fungi from soil samples of peat layers in Aomori and Oita Prefectures in Japan and Perth and Kinross district in Scotland by a serial dilution plate technique. The mycobiota in each peat soil showed some common and characteristic features. The abundance of fungal isolates (CFU/g) from peat soil was low: about 1/3 to 1/30 compared with evergreen or coniferous forests or cultivated soil. Trichoderma or Mucorales species were scarcely observed; these fungi occupied only 3% of the total number of colonies. On the other hand, fungi such as Conioscypha and Tolypocladium that are normally isolated rather rarely were encountered at a comparatively high rate. Acremonium guillematii and Tolypocladium cylindrosporum were recorded for the first time in Japan. Sterile fungi occupied 50% of the total number of isolates. The low abundance of fast-growing fungi enabled us to pick slow-growing fungi up easily from the isolation medium. It is interesting that species not previously described in Japan, or scarcely reported, were isolated commonly from both Japanese and Scottish samples. A peat soil sample is therefore an attractive source of untapped microbial resources.     

Edwardsiella hoshinae,a new species of enterobacteriaceae

Eight strains isolated from birds, reptiles, and water constitute a new DNA hybridization group that is 37–58% related toEdwardsiella tarda and less than 10% related to other species of Enterobacteriaceae (SI nuclease method). This homogeneous group (78–100% relatedness within the group) constitutes a new species that is namedEdwardsiella hoshinae sp. nov. (type strain, CIP 78.56 ATCC 33379). Strains of this species produce acid fromd-mannitol, sucrose,d-trehalose, and salicin, and give a positive malonate test. Seven other strains that produced acid fromd-mannitol and sucrose (but not fromd-trehalose and salicin) and were malonate negative were found to belong to theEdwardsiella tarda DNA hybridization group. The base composition of the DNAs ofE. tarda andE. hoshinae is 55–58 mol% G+C.     

喀斯特典型地区烟管荚蒾AM真菌多样性研究

烟管荚蒾是喀斯特地区灌木丛的主要组成植物。以茂兰喀斯特森林为采样地点,对烟管荚蒾AM真菌进行了分离、鉴定与多样性分析,并对优势菌种进行初步的接种研究。结果表明:烟管荚蒾根系的菌根侵染率为82.1%,从根际土壤分离到AM真菌2属16种,球囊霉属(Glomus)7种,无梗囊霉属(Acaulospora)9种。优势种为根内球囊霉(Glomus intraradices)、皱壁无梗囊霉(Acaulospora rugosa)和刺无梗囊霉(A. spinosa)。优势菌种接种紫花苜蓿(Medicago sativa),促生作用明显,并显著提高了SOD、POD和CAT酶活性。该研究对于探讨喀斯特地区AM真菌的多样性与独特性,筛选优良的宿主植物和与之高效共生的AM真菌具重要意义。     

Basidiobolus haptosporus is frequently associated with the gamasid mite Leptogamasus obesus

Two species of mites inhabiting a pine forest soil were screened for associated fungi. The fungal community composition was assessed in 49 mite and 19 soil samples by environmental PCR with a focus on fungi of the genus Basidiobolus. PCR products of the fungal ITS rRNA gene were analyzed by sub-cloning, RFLP-analysis, and sequencing. Thereby Basidiobolus haptosporus was found for the first time to be frequently associated with the gamasid mite species Leptogamasus obesus, while being absent from the oribatid mite Oppiella subpectinata, and from the surrounding soil. The fungus was isolated in pure culture for a detailed morphological characterization and experimental approaches concerning the nature of this fungus-mite association. The experiments and a supporting microscopic screening of freshly captured gamasid mites revealed no indications for the fungus being localized in the mites' gut or haemocoel, but a single spore was found attached to an individual of L. obesus. However, an exclusive phoretic association does not satisfactorily explain the frequent detection of B. haptosporus DNA on or in L. obesus, and the absence of the fungus from soil samples seems not to be in line with its assumed ecology as a widespread saprobic soil fungus. Therefore, a second host species in the life cycle of B. haptosporus is discussed as a working hypothesis.