New sources of cytochalasins A and B from dematiaceous hyphomycetes

One hundred isolates of 27 species belonging to 13 genera of dematiaceous hyphomycetes were screened for production of cytochalasins A and B. Most of these isolates (94) were obtained from Assiut University Culture Collection, Botany Department, Faculty of Science, Assiut University, Egypt; three isolates from CBS, The Netherlands; two isolates from DSM, Germany; and one isolate from IMI, UK. The results revealed that 10 isolates of six species representing five genera of fungi produced cytochalasins A and/or B. These species are Alternaria chlamydospora, Cochliobolus spicifer, Diplococcum spicatum, Phoma herbarum, Phoma multipara and Setosphaeria rostrata. This is the first report for the production of cytochalasins A and/or B by these species of dematiaceous hyphomycetes.     

Selective medium for isolation of Fusarium species and dematiaceous hyphomycetes from cereals

A selective medium containing 2 micrograms of dichloran per ml, 200 micrograms of chloramphenicol per ml, and 1.5% bacteriological peptone was developed for the isolation of Fusarium species and dematiaceous hyphomycetes from cereals. The medium, designated DCPA, was shown to select against species of Aspergillus, Penicillium, Cladosporium, and mucoraceous fungi. DCPA was evaluated for use as an enumeration medium and compared satisfactorily with dichloran-rose bengal-chloramphenicol agar when both media were tested with a range of cereal samples. Fusarium species and dematiaceous hyphomycetes produced well-formed colonies with good conidial production on DCPA, permitting rapid identification of such isolates on this medium.     

Selective medium for isolation of Fusarium species and dematiaceous hyphomycetes from cereals.

A selective medium containing 2 micrograms of dichloran per ml, 200 micrograms of chloramphenicol per ml, and 1.5% bacteriological peptone was developed for the isolation of Fusarium species and dematiaceous hyphomycetes from cereals. The medium, designated DCPA, was shown to select against species of Aspergillus, Penicillium, Cladosporium, and mucoraceous fungi. DCPA was evaluated for use as an enumeration medium and compared satisfactorily with dichloran-rose bengal-chloramphenicol agar when both media were tested with a range of cereal samples. Fusarium species and dematiaceous hyphomycetes produced well-formed colonies with good conidial production on DCPA, permitting rapid identification of such isolates on this medium.     

Primo contributo alla conoscenza di alcuni ifali demaziacei del Sahara algerino

Abstract

First contribution to the knowledge of some dematiaceous hyphomycetes of algerian Sahara.—Nine dematiaceous hyphomycetes, found in the algerian Sahara, near the Ouarglà Oasis, are here described. Three are reported as new species and two as new records for the desertic provenance.     

Screening for a “new” enzyme in nature: Haloperoxidase production by Death Valley dematiaceous hyphomycetes

Haloperoxidases are enzymes that have the ability to halogenate a broad range of substrates [10]. To find a biologically produced haloperoxidase that could function at a pH greater than 3.0 and at a temperature greater than 19°C, dematiaceous hyphomycetes were isolated from the Death Valley desert and screened for their ability to produce such an enzyme. A qualitative assay using bromophenol red was employed in situ over a 12-day fermentation period. Several dematiaceous hyphomycetes, such asDreschlera haloides andUlocladium chartarum, produced haloperoxidases that were active in broth culture at 19, 25, and 34°C at pH 7.0 and 8.0.     

湖南张家界国家森林公园土壤中的暗色丝孢菌

自湖南张家界国家森林公园采集的15份土样中,分离获得32个暗色丝孢菌分离物,经鉴定分别属于15属中的19个种。其中,湖南小带孢Taeniolella hunanensis为一新种,昏暗色串孢Torula caligans和小孢维郎那霉Veronaea parvispora为中国新记录种。对其它16个中国已报道种亦作了分离生境的引证。研究过的标本(干制培养物)与活菌种存放在山东农业大学植物病理学标本室(HSAUP)。     

甘肃河西走廊土壤中的暗色丝孢菌

从甘肃河西走廊的25份土样中分离出39个暗色丝孢菌分离物,经鉴定分别属于16个属的27个种。其中厚垣链格孢Alternaria chlamydospora、黑小枝顶孢Acremoniella atra和疣小枝顶孢Acremoniella verrucosa为中国新记录种:士栖葡萄穗霉Stachybotrys terrestris为新种。研究过的标本(干制培养物)与活菌种均保存在山东农业大学植物病理学标本室(HSAUP)。     

Production of bacteriocin by isolates ofYersinia enterocolitica from fresh buffalo milk

Fifty isolates ofYersinia enterocolitica from fresh buffalo milk were screened for the production of bacteriocin using isolates as indicators. Seven isolates (14%) were bacteriocin producers at 22°C which had more bacteriolytic activity at 37°C. Only one isolate produced bacteriocin at both temperatures.     

Variability in Indian Isolates of Arthrobotrys dactyloides Drechsler: A Nematode-Trapping Fungus

Five isolates of Arthrobotrys dactyloides (A, B, C, D, and E) were isolated from different locations of India. Their variability in relation to morphology, radial growth, and nematode capturing or trap-forming ability was observed. All of the five isolates produced two-celled slender conidia, whereas wider two- and three-celled conidia were produced by isolates A, C, D, and E only. The wider two- and three-celled conidia were not observed in cultures of isolate B. The isolate B produced macroconidia as well as microconidia. The microconidia were produced on separate conidiophores of smaller size. Macroconidia and microconidia were never produced on the same conidiophore, but the two types of conidiophores were produced on same or different hyphae. Similar to macroconidia, the microconidia also produced constricting rings of smaller size in presence of Meloidogyne graminicola. The constricting rings formed on microconidia did not capture second-stage juveniles of M. graminicola because of their smaller size. Among all the isolates, isolate B showed slow growth and higher nematode-capturing ability or trap-forming ability.     

苏云金芽孢杆菌芽孢萌发相关基因gerM的克隆及功能研究

采用土壤平板法和稀释平板法,自湖北神农架自然保护区的14份土壤样品中分离得到40个暗色丝孢菌分离物,鉴定为16属23种。其中,湖北弯孢Curvularia hubeiensis为一新种,嗜热革节孢Scytalidium thermophilum和禾色串孢Torula graminis为中国新记录种。对新种及中国新记录种作了详细的描述。其余20种为国内已报道种。所有研究菌株的干制培养物标本与活菌种均存放在山东农业大学植物病理学标本室(HSAUP)。     

Morphological and physiological comparisons ofHelicobasidium mompa andH. purpureum

Morphological and physiological comparisons were made of sevenHelicobasidium mompa isolates and fourH. purpureum isolates. Colonies of theH. mompa isolates were thin, dense, or hard and dense, and most were pale brown to brown or dark brown, while that of isolate 344c was pinkish. Colonies ofH. purpureum isolates were hard and dense, and their colonies were dark brown. Diameters of hyphae were similar forH. mompa andH. purpureum. Dimensions of conidia and morphology of conidiophores ofH. mompa isolate 344c were close to those ofH. purpureum reported previously.H. mompa isolates grew well at 23°C, 25°C or 27°C, while all isolates ofH. purpureum grew well at 23°C. Growth rates ofH. purpureum isolates was almost the same as those ofH. mompa isolates with slow growth. Polygaracturonase activity at pH 3 was variable among the isolates for bothH. mompa andH. purpureum. Itaconic acid was produced abundantly by three isolates ofH. mompa but not produced by isolate AH130, whereas all isoaltes ofH. purpureum produced a small amount of itaconic acid.     

柴达木盆地中西部土壤中暗色丝孢菌群落多样性分析

从柴达木盆地中西部采集土样59份,涵盖的生态类型有:沙漠、戈壁、湿地、小镇-绿洲等。分离获得暗色丝孢菌108株,经鉴定分属于15属。利用种群优势度、Shannon-Wiener多样性指数、物种均匀度、生态位宽度四项指数,对柴达木盆地中西部不同生境土壤中的有关暗色丝孢菌物种(属级)进行物种多样性分析。结果表明,该地区土壤中暗色丝孢菌的物种优势度存在明显差异:沙漠生境中,链格孢属Alternaria和细基格孢属Ulocladium真菌优势度较高;戈壁生境中,单格孢属Monodictys真菌的优势度最高;湿地和小镇-绿洲生境中,则分别以瓶霉属Phialophora和枝孢属Cladosporium真菌占优势。在小镇-绿洲生境中,土壤暗色丝孢菌的Shannon-Wiener多样性指数最高,均匀度较低;而在沙漠和戈壁生境中多样性指数明显较低,而物种的均匀度较高。在上述四类生境中,链格孢属Alternaria和细基格孢属Ulocladium真菌具有较宽的生态位,为广适性物种;而平脐蠕孢属Bipolaris、卷旋孢属Cirrenaria、弯孢属Curvularia、矛束霉属Doratomyces、粘束孢属Graphium、漆斑霉属Myrothecium、齿梗孢属Scolecobasidium、帚霉属Scopulariopsis、节隔孢属Scytalidium和葡萄穂霉属Stachybotrys10个属真菌的生态位较窄,为狭适性物种。     

Analysis of esterase zymograms ofFusarium sambucinum and related species

Esterase zymograms were obtained following polyacrylamide slab gel electrophoresis of protein extractsFusarium sambucinum and related species originating from different geographic locations and different matrices. The sites of esterase activity were recorded, and the R_fs were calculated. The data were used for the construction of phenograms by cluster analysis and nonlinear mapping by computerized classification techniques. The fifteen isolates ofF. sambucinum, the eight isolates ofF. torulosum and the six isolates ofF. spec. nov. each had identical profiles, and are therefore electrophoretically distinct species. The isolates ofF. sarcochroum, one ofF. sambucinum sensu lato (BBA 64280) and fifteen isolates ofF. sambucinum were electrophoretically indistinguishable from each other. We assume they are synonymous. The isolate ofF. bactridioides, one ofF. sambucinum sensu lato (BBA 64993) and eight isolates ofF. torulosum had uniform EST patterns, therefore the two species are electrophoretically identical. We assume they are also synonymous. The remaining three isolates ofF. sambucinum sensu lato are somewhat closely related toF. sambucinum isolates on the basis of our investigations.     

Soil mycoflora from the Dead Sea Oases of Ein Gedi and Einot Zuqim (Israel)

Samples were taken from the top 10 cm of soils from 24 points in the Ein Gedi area. Among 329 isolates, 142 species were identified: 11 genera of ascomycetes, one genus of coelomycetes, 28 genera of hyphomycetes, 7 genera of zygomycetes and one yeast, in addition to some unidentified basidiomycetes. The hyphomycetes were represented by 17 dematiaceous, 9 mucedinaceous and two tuberculariaceous. Melanconiaceous and stilbellaceous genera were not found. Two new varieties of Microascus recently described were reisolated. No strict thermophiles or halophiles were obtained. There is apparently no very characteristic or specific fungal flora of the Dead Sea Oases although it was different from that found in the desert soil surrounding this area.     

Temperature and Sporulation of Aquatic Hyphomycetes

Temperature appears to be an important factor affecting the occurrence and distribution of aquatic hyphomycetes, the dominant leaf litter-decomposing fungi in streams. We compared conidium production by eight species of aquatic hyphomycetes grown on yellow poplar leaves in stream-simulating microcosms at three temperatures (15, 20, and 25°C). The greatest conidium production occurred at 15°C for one species, 20°C for two species, and 25°C for two species. Two species produced similar numbers of conidia at 20 and 25°C, and one species produced similar numbers of conidia at all three temperatures. Linear growth rates were determined on malt extract agar. Six species had the same pattern of temperature responses for growth on malt extract agar as for sporulation on leaves, as shown by the positive correlations between the two parameters at the three temperatures. The species examined also exhibited differences in number of conidia produced from a similar amount of leaf material at a given temperature. These differences appeared to be due primarily to differences in individual conidium mass (determined by weighing conidia produced from cultures), as shown by the relationship of the type Y = k/X (r² = 0.96), where Y is the number of conidia produced, X is the individual conidium mass in milligrams, and k is a constant empirically determined to be 2.11. This finding supports the hypothesis that aquatic hyphomycetes allocate similar amounts of their resources to reproduction but vary with respect how these resources are partitioned into reproductive units (conidia).     

Mycotoxin production and evolutionary relationships among species of Aspergillus section Clavati

Aspergillus clavatus is a commonly encountered fungus in the environment, producing a number of mycotoxins including patulin, kojic acid, cytochalasins and tremorgenic mycotoxins. A. clavatus belongs to Aspergillus section Clavati together with six other species, all of which possess clavate-shaped vesicles. Patulin production was analysed by thin layer chromatography and high performance liquid chromatography, while a primer pair developed for the detection of an iso-epoxydon dehydrogenase gene involved in the biosynthesis of patulin in penicillia was used to detect the ability of patulin production in the isolates examined. A good correlation was observed between patulin producing properties, and the presence of an iso-epoxydon dehydrogenase gene fragment among the isolates tested. A. longivesica was found for the first time to produce patulin. Ribotoxin production was also examined using a PCR-based approach. Ribotoxins were detected for the first time in an A. pallidus and a Hemicarpenteles acanthosporus isolate. A phylogenetic analysis of intergenic transcribed spacer sequence data indicated that most isolates belong to two main clades that have also been identified earlier based on 26 S rDNA sequence data. A. pallidus isolates clustered together with A. clavatus strains. Although A. clavatus isolates produced highly homogeneous random amplified polymorphic DNA profiles, phylogenetic analysis of these data let us cluster A. clavatus isolates into distinct clades. Correlations were not observed between either patulin or ribotoxin production, and the taxonomic position of the isolates tested, indicating that patulin and ribotoxin producing abilities were lost several times during evolution of Aspergillus section Clavati. Although patulin was earlier found to inhibit mycovirus replication, one of the mycovirus carrying isolates also produced patulin, and both carried the iso-epoxydon dehydrogenase gene. This revised version was published online in June 2006 with corrections to the Cover Date.     

Phenotypic differences among single-oospore cultures of Phytophthora palmivora and P. botryosa from Heavea brasiliensis

Oospores ofPhytophthora palmivora andP. botryosa fromHevea brasiliensis were produced when complementary strains of the same species were incubated on V-8 juice agar in continuous darkness, with or without a subsequent period of continuous light. The oospores germinated at a rate of 15–30 % in demineralised water at 26 °C in normal daylight conditions. Other substrates did not improve the germination rate. Single-zoospore colonies derived from sporangia formed by a single oospore were similar to each other in morphology and in pathogenicity toHevea leaves. Over 400 single-oospore isolates from four intraspecific matings ofP. palmivora, and 102 from one pairing ofP. botryosa, were examined. The progeny differed in morphological appearance, mating behaviour, temperature-growth relations, pathogenicity toHevea leaf petioles and cacao pods, rate of production, shape and size of sporangia and in the abundance of chlamydospores. The progeny from an intraspecific cross ofP. botryosa was more variable, with a few isolates being similar in appearance toP. palmivora, having permanently lost their parental characteristic of producing small oval sporangia in clumps. One isolate in particular was indistinguishable fromP. palmivora in morphology and in its ability to produce functional oospores when mated withP. palmivora. Oospores formed by interspecific crosses could not be germinated. With both species, many progeny was less pathogenic than the parents, and many completely non-infective isolates with respect toHevea, cacao and other host plants were produced. Sexual reproduction resulted in a diversity of phenotypes, and both parental types and recombinants were recovered.     

Isolation and characterization of new chlamydosporol related metabolites ofFusarium chlamydosporum andFusarium tricinctum

Fusarium chlamydosporum strain T-826 isolated from corn in the USA produced chlamydosporol and two analogs which have been identified by various spectroscopic techniques as: 7,8-dihydro-5-hydroxy-4-methoxy-trans-7,8-dimethyl-2H,5H-pyrano(4,3-b)pyran-2-2-one (or isochlamydosporol) and 4-methoxy-5-hydroxymethyl-6-(3-butan-2-ol)-2H-pyran-2-one (or chlamydospordiol). Chlamydosporol (compounda+b) chlamydospordiol (compoundc) and isochlamydosporol (compoundd) were produced together (up to 6000 µg/g) by 3 out of 11 isolates ofF. chlamydosporum and by 3 out of 24 isolates ofF. tricinctum from various substrates and geographic origin. Three isolates ofF. chlamydosporum and one isolate ofF. tricinctum produced only chlamydospordiol and 2 isolates ofF. tricinctum produced chlamydosporol (a+b), and chlamydospordiol (c)PRC Publication, No. 1518     

Microfungi from decaying leaves of two rain forest trees in Puerto Rico

Fungal species richness and abundance were compared in leaf litter of two tree species,Guarea guidonia andManilkara bidentata, in the Luquillo Mountains of Puerto Rico. Four litter samples yielded a total of 3337 isolates, ranging from 591 to 1259 isolates/sample. The number of species/sample ranged from 134 to 228. Many uncommon litter hyphomycetes were recovered as well as coelomycetes, sterile strains, endophytes, and phytopathogens. Species-abundance distributions revealed a typical pattern of a few abundant species and a high proportion of rare species. Similarities in fungal species composition were not correlated with host species or with the site. Replicate samples examined by the moist chamber technique yielded a total of 24 species among the four litter samples. The particle filtration method indicated that leaves ofG. guidonia were more species-rich, while moist chambers indicated leaves ofM. bidentata were more species-rich. The moist chamber technique underestimated the number and species of viable fungi.     

Bactrodesmiastrum,a new genus of lignicolousHyphomycetes

A new genusBactrodesmiastrum Hol.-Jech. is established for a fungus of dematiaceous hyphomycetes collected on decaying wood ofFagus sylvatica in Czechoslovakia. The only species,B. obscurum Hol.-Jech. is described and illustrated.