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Bioactivity-directed fractionation of the organic mycelium extract of the endophytic fungus Acremonium camptosporum W. Gams (Clavicipitaceae), isolated from the leaves of Bursera simaruba (Burseraceae), led to the isolation of six major heterodimeric polyketides, including one not previously characterized acremoxanthone derivative. In addition, the already known acremoxanthone C, acremonidins A and B, and acremoxanthones A and B were obtained. The structure of the new compound was established by extensive NMR studies, including DEPT, COSY, NOESY, HSQC, and HMBC methods. The trivial name proposed for this compound is acremoxanthone E. In addition, the structure of acremoxanthone C was unequivocally established for the first time, through X-ray crystal-structure analysis. The anti-oomycete activities of the pure compounds were tested against four economically important phytopathogenic oomycetes. Inhibitory concentration for 50% diameter growth reduction, IC50 , values for the four phytopathogens ranged from 6 to 38 μM. Also, in parallel, the cytotoxic activities against six cancer cell lines were evaluated showing IC50 values similar to those of cisplatin. To the best of our knowledge, this is the first report on three different groups of heterodimeric polyketides, linked by a bicyclo[3.2.2]nonene, such as xanthoquinodins, acremonidins, and acremoxanthones, which are isolated from an endophytic fungus. In addition, a common biosynthetic origin could be proposed., (Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.)

Muscodor yucatanensis, an endophytic fungus, was isolated from the leaves of Bursera simaruba (Burseraceae) in a dry, semideciduous tropical forest in the Ecological Reserve El Eden, Quintana Roo, Mexico. We tested the mixture of volatile organic compounds (VOCs) produced by M. yucatanensis for allelochemical effects against other endophytic fungi, phytopathogenic fungi and fungoids, and plants. VOCs were lethal to Guignardia mangifera, Colletotrichum sp., Phomopsis sp., Alternaria solani, Rhizoctonia sp., Phytophthora capsici, and P. parasitica, but had no effect on Fusarium oxysporum, Xylaria sp., the endophytic isolate 120, or M. yucatanensis. VOCs inhibited root elongation in amaranth, tomato, and barnyard grass, particularly those produced during the first 15 days of fungal growth. VOCs were identified by gas chromatography/mass spectrometry and included compounds not previously reported from other Muscodor species and the previously reported compounds octane, 2-methyl butyl acetate, 2-pentyl furan, caryophyllene, and aromadendrene. We also evaluated organic extracts from the culture medium and mycelium of M. yucatanensis on the same endophytes, phytopathogens, and plants. In general, extracts inhibited plants more than endophytic or phytopathogens fungi. G. mangifera was the only organism that was significantly stimulated by both extracts regardless of concentration. Compounds in both organic extracts were identified by gas chromatography/mass spectrometry. We discuss the possible allelopathic role that metabolites of M. yucatanensis play in its ecological interactions with its host plant and other organisms.

Chemical investigation of the mycelium of Edenia gomezpompae, a newly discovered endophytic fungus isolated from the leaves of Callicarpa acuminata (Verbenaceae) collected from the ecological reserve El Eden, Quintana Roo, Mexico, resulted in the isolation of four naphthoquinone spiroketals, including three new compounds and palmarumycin CP2 (4). We elucidated the structures of the metabolites by extensive NMR spectroscopy studies, including DEPT, COSY, NOESY, HSQC, HMBC, and chiroptical methods. The trivial names proposed for these compounds are preussomerin EG1 (1), preussomerin EG2 (2) and preussomerin EG3 (3). In addition, the X-ray data for 4 were obtained. The bioactivity of the mycelial organic extracts and the pure compounds was tested against three endophytic fungi (Colletotrichum sp., Phomopsis sp., and Guignardia manguifera) isolated from the same plant species (C. acuminata, Verbenaceae) and against four economically important phytopathogenic microorganisms (two fungoid oomycetes, Phythophtora capsici and Phythophtora parasitica, and the fungi Fusarium oxysporum and Alternaria solani). Spiroketals 1-3 displayed significant growth inhibition against all the phytopathogens. IC50 values for the four phytopathogens were from 20 to 170 microg/ml. Palmarumycin CP2 (4) was not bioactive against any of the fungi tested. Compound 1 showed the strongest bioactivity. The acetylated derivatives of preussomerin EG1 (1), 1a and 1b, were obtained and their biological activity was tested on endophytes and phytopathogens. Preussomerin EG1 1, 1a and 1b exhibited significant bioactivity against all microorganisms tested with the exception of Alternaria solani. This is the first report of allelochemicals with antifungal activity from the newly discovered endophytic fungus E. gomezpompae.

Periconia variicolor was isolated from water of an evaporation pond used for salt production on the southwestern coast of Puerto Rico. On the basis of cultural and morphological characteristics and ITS sequence it is describe as a new species of Periconia.

We describe a perithecial, pleomorphic ascomycetous fungus from the Early Devonian (400 mya) Rhynie chert; the fungus occurs in the cortex just beneath the epidermis of aerial stems and rhizomes of the vascular plant Asteroxylon. Perithecia are nearly spherical with a short, ostiolate neck that extends into a substomatal chamber of the host plant; periphyses line the inner surface of the ostiole. The ascocarp wall is multilayered and formed of septate hyphae; extending from the inner surface are elongate asci interspersed with delicate paraphyses. Asci appear to be unitunicate and contain up to 16 smooth, uniseriate-biseriate ascospores. The method of ascospore liberation is unknown; however, the tip of the ascus is characterized by a narrow, slightly elevated circular collar. Ascospores appear 1-5 celled, and germination is from one end of the spore. Also present along the stems and interspersed among the perithecia are acervuli of conidiophores that are interpreted as the anamorph of the fungus. Conidiogenesis is thallic, basipetal and probably of the holoarthric-type; arthrospores are cube-shaped. Some perithecia contain mycoparasites in the form of hyphae and thick-walled spores of various sizes. The structure and morphology of the fossil fungus is compared with modern ascomycetes that produce perithecial ascocarps, and characters that define the fungus are considered in the context of ascomycete phylogeny.

Poroleprieuria gen. nov. is described and illustrated to accommodate P. rogersii in the Xylariaceae, Xylariales. This ascomycete, known only from the type collection, is characterized by reniform, light brown, smooth ascospores with a germ pore; cylindrical, persistent asci lacking an apical apparatus, septate persistent paraphyses, and erumpent, erect, dark brown, fragile, subcylindrical stromata. The characteristics of this xylariaceous fungus were compared with those of some other ascomycetes having superficially similar cylindrical stromata or ascospores with germ pores.

The perithecial ascomycete Ophiodothella vaccinii causes a leafspot disease of sparkleberry (Vaccinium arboreum), in which an anamorph is produced early in the life cycle of the fungus. The anamorph forms shiny, black, pulvinate conidiomata that contain a single central pore. After initial infection, fungal hyphae permeate the interior tissues of the leaf, creating lesions. Conidiomata are initiated by the formation of a small layer of intertwined, thicker-walled hyphae beneath the epidermis of the lesion. Near the center of this hyphal layer a subglobose collection of thick-walled hyphae is formed. This hyphal collection grows upward, becoming conical and pressing against the epidermis. Elongation of a columnar apex of the hyphal collection ruptures the epidermis, creating a pore. Subsequent expansion and development of conidiophores and conidia push the epidermis upward, lifting it away from the column, opening the pore and allowing conidia to emerge. The conidioma is regarded as a modified acervulus.

A detailed study of ascomal morphology and development in Cercophora palmicola showed that ontogeny is ascohymeniaceous, giving rise to an ostiolate perithecium. Ascomal initials consist of a coiled ascogonium surrounded by several layers of hyphae whose cells become pseudoparenchymatous. The centrum of the young ascoma is composed of a few rows of large, thin-walled pseudoparenchymatous cells that line the ascomal wall, with the central region filled by tightly packed, filamentous paraphyses. The ascogenous system forms along the inside of the layer of pseudoparenchymatous cells at the base of the paraphyses and gives rise to unitunicate asci that grow up among the paraphyses. The wall of the mature perithecium is greatly thickened. It is composed of three regions: a thin outer region of darkly pigmented, angular cells with thickened walls; a broad central region of cells with gelatinized walls; and a thin inner region of flattened cells. Ascomal ontogeny in C. palmicola conforms well to the Sordaria type of development, as defined by Huang.

Seven strains of filamentous fungi and one yeast were isolated from flax that was dew retted in the United States. These filamentous fungi were subcultured to purity and identified, and six appear not to have been reported earlier as isolates from dew-retted flax. Five of the purified U.S. strains, two fungi isolated from flax that was dew retted in Europe, and a laboratory culture of Aspergillus sojae were tested for their ability to ret flax stems. The monocultures were evaluated for the degree of retting, fiber strength, dry weight loss, and tactile response (i.e., feel of softness) as reflected in the retted fiber. Structural modifications of representative samples of the retted flax were assessed by scanning electron microscopy. All of the filamentous fungi were able to carry out some retting, whereas the isolated yeast could not. All organisms produced pectinases when they were cultivated in shake flasks on ball-milled flax as the sole carbon source. Some fungi also produced cellulases, mannanases, and xylanases. Rhizomucor pusillus and Fusarium lateritium were noteworthy as retting organisms by their high level of pectinase activity, ability to attack noncellulosic cell types without attacking cellulose, capacity to penetrate the cuticular surface of the stem, and efficient fiber release from the core. The results indicated that these organisms deserve further study as potential organisms for retting of bast fibers in industrial applications.

ES Luttrell was a mycologist who spent 42 of his 44 professional years at the University of Georgia, first at the Georgia Experiment Station in Griffin and later at the main campus in Athens. He is best known for his innovative classification scheme for the perithecial ascomycetes, in which orders were based on patterns of ascomal ontogeny and mode of ascus dehiscence. This work established him as an authority on ascocarp development. His later studies on the classification of the Helminthosporium complex, in which he showed that small differences in conidium germination and structure could be correlated with distinct teleomorphs, brought him recognition from plant pathologists as well. These studies were notable for his attention to detail and the quality of his work. His contributions to mycology and plant pathology were numerous and varied and brought him various awards later in his career. To his colleagues he served as administrator, teacher, mentor and friend.

One hundred and forty-eight isolates of Aspergillus flavus and A. parasiticus were isolated from 5,608 pecans obtained from Chicago and Georgia markets. The percentage of internal contamination by these species was 7.3% in the Chicago market pecans and 1.7% in those from markets in Georgia. Of the 148 isolates, 93% of the A. parasiticus, but only 54% of the A. flavus, were capable of producing aflatoxin. Overall, 57% of the isolates were potentially aflatoxigenic. A. parasiticus isolates generally produced a greater amount of aflatoxins than A. flavus.

A screening study of 121 fungus isolates, representing 29 species, for aflatoxin synthesis demonstrated this property only in Aspergillus flavus and A. parasiticus. Eight of the organisms found negative were isolates reported by other investigators to produce aflatoxin. Since similar negative reports have come from several other workers, it is concluded that only the A. flavus group of Aspergillus can presently be certified as sources of these toxins. Reasons for possible false-positive findings are discussed along with precautionary measures and differential analytical procedures useful in aflatoxin screening studies.

Studies were conducted to determine the effectiveness of propylene oxide (PO) treatment in controlling the microflora of pecans. As used commercially, PO has little effect on internal bacteria and fungi in pecan halves. Tests of surface washings of commercially treated pecans showed a reduction of 96% in coliform bacteria following PO treatment. Under controlled laboratory conditions, PO gave 80 to 92% reduction of surface microflora and at least 64% reduction of internal flora, but neither bacteria nor fungi could be eliminated completely, even with high dosages. Current assay methods for determining bacterial content of nutmeats were shown to be inadequate because they utilize only surface washings and thus do not give an accurate picture of the total bacterial population of the nutmeat. Consequently, such assays do not permit an accurate assessment of any potential health hazard related to these organisms.

Of 120 isolates of the Aspergillus flavus group from pecans used in bakery products, 85 were shown to produce aflatoxin on yeast extract sucrose medium. Extracts from moldy sections of raw pecans obtained commercially at the retail level showed aflatoxin-like spots on thin-layer chromatography. Cooked (autoclaved) pecans inoculated with toxigenic isolates of A. flavus were also good substrates for aflatoxin production.