Toxigenic fungi isolated from roquefort cheese

To evaluate the potential for mycotoxin production by fungi contaminating blue-veined cheese, as well as by the ripening fungus,Penicillium roqueforti, the fungal flora of six of local and imported brands was determined. A total of 19 fungi were isolated from the six brands tested. Fourteen of the isolates were toxic to chicken embryos. The toxigenic fungi produced the following mycotoxins:Aspergillus fumigatus, kojic acid;A. versicolor, sterigmatocystin;Penicillium roqueforti, penicillic acid and unidentified toxic metabolites.     

Toxigenic fungi associated with stored corn

A total of 246 fungal isolates were obtained from 25 moldy corn samples collected in central Iowa. Either water or ether extracts of all corn samples except one exhibited some degree of toxicity in mice and/or ducklings. At least one toxigenic isolate was obtained from each corn sample. Extracts of cultures of 99 of the fungal isolates, involving 13 genera, produced death in one or more of the assay animals. The majority of the toxigenic isolates belonged to the generaAspergillus andPenicillium. Three isolates ofTrichothecium roseum were highly toxic to ducklings and mice. The ducklings exhibited a flaccid paralysis shortly after receiving an oral dose of extracts of these three isolates. Death frequently occurred following a second oral dose given 24 hr later. Mice given intraperitoneal injections of extracts ofT. roseum first exhibited lethargy and intermittent tremors, then hyperemotivity, roughening of the hair coat, abdominal respirations, incoordination, dyspnea and clonic convulsions with death occurring usually within 10 to 20 min.

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Zusammenfassung Insgesamt sind 246 Pilzisolierungen von 25 verschimmelten Getreideproben, die in Zentral-Iowa gesammelt worden sind, erhalten worden. Sowohol Wasser- wie Aether-Extrakte von allen Getreideproben zeigten eine gewisse Toxizität in Mäusen als auch in Entchen außer einer einzigen Probe. Kulturextrakte von 99 der Pilzisolierungen, die 13 Gattungen umfaßten, verursachten den Tod in einem oder in mehreren Versuchstieren. Die Mehrheit der toxischen Isolierungen gehörte den GattungenAspergillus undPenicillium an. Drei Isolierungen vonTrichothecium roseum waren hoch toxisch für Entchen und Mäuse. Die Entchen zeigten eine schlaffe Paralyse kurz nachdem sie eine orale Dosis der Auszüge dieser drei Isolierungen erhalten hatten. Tod erfolgte häufig nach der zweiten oralen Dosis innerhalb 24 Stunden. Mäuse, die eine intraperitoneale Injektion der Auszüge vonT. roseum erhielten, zeigten erst eine Lethargie und einen intermittierenden Tremor, dann eine Hyperemotivität, aufgerauhte Haarbedeckung, abdominale Atmung, Inkoordination, Dyspnoe, klonische Zuckungen und Tod gewöhnlich innerhalb 10 bis 20 Minuten.

     

Toxigenic fungi and the deterioration of Nigerian poultry feeds

Growth of toxigenic strains of Aspergillus clavatus Des. and Aspergillus flavus Link at 30°C on milled poultry feeds led to a considerable decrease in the protein, oil and crude fibre contents of the feed substrate. A corresponding increase in the free fatty acid fractions of the feeds due to the activities of these microbes was also recorded. Rapid degradation of the feedstuff by both species was recorded at a temperature of 25°C and 30°C and a pH range of 4.8–6.4. When grown on feed infusion broth at 30°C, the highest amounts of mycelial production with sporulation of both fungal species occurred within the 8-day incubation period. A determination of their extra-cellular enzyme profile showed the production of amylases, pectate lyase, cellulases, proteases, lipases, xyalanases, DNase and RNase.All the carbon and nitrogen sources used (except L-sorbose and DL-tryptophan), supported good mycelial growth with sporulation. An optimal CN ratio of 5.04.5 and 7.53.0 was recorded for growth and sporulation of A. clavatus. For A. flavus, a CN ratio of 7.54.5 was found best for growth and 5.03.0 for sporulation.     

Toxigenic saprophytic fungi in marine shellfish farming areas

Toxigenic saprophytic fungi were isolated from samples of shellfish, sediment and seawater obtained from marine shellfish farming areas. The 456 strains identified included 12 different genera, with a clear predominance (68%) of Penicillium, Aspergillus, Trichoderma and Cladosporium. To assess the risk of poisoning due to the presence of these fungi in shellfish farming areas, the strains were cultured in liquid medium, filtered, and tested on larvae of Artemia salina, a small crustacean highly sensitive to mycotoxins. Thirty-five point five percent of the strains proved active with this test. This study confirms the existence of fungi in shellfish farming areas, as suggested by our earlier work showing that filter-feeding shellfish accumulate toxic metabolites of fungal origin. The presence of fungi in the marine environment represents a real risk of poisoning through the consumption of contaminated shellfish.This revised version was published online in October 2005 with corrections to the Cover Date.     

Root rot disease incidence and severity on some legume species grown in Samsun and the fungi isolated from roots and soils

Abstract

Root rot disease is very common in the bean, soybean, faba bean and pea plants growing areas in Samsun province. Disease incidence and severity were detected the highest at 93.8% and 55.4% in the bean growing area, and the lowest at 64.0% and 24.3% in the faba bean growing area respectively. In this study, a total of 2714 fungal isolates were obtained from some legume plants and soil samples. The most common fungi isolated from root and soil samples were Fusarium spp., multinucleate Rhizoctonia (MNR), binucleate Rhizoctonia (BNR) and Pythium spp. respectively. Fusarium spp. were isolated at high rates from all the examined areas. MN Rhizoctonia and BN Rhizoctonia were isolated both from inner and coastal areas of the province, whereas Pythium spp. were isolated in costal areas, except for the Vezirköprü district which is situated in the inner area. When looking at the interactions among pathogens causing root rot, it was found the great majority of the samples (30.4%) isolated both Fusarium spp. and MNR-BNR group fungi, whereas Fusarium spp. and Pythium spp. were isolated together from 10.9% of the samples and MNR-BNR and Pythium spp. from only 1.5% of the samples.     

源于海洋真菌的抗肿瘤天然产物

海洋真菌因其特殊的生存环境和代谢机制而具有产生新型生物活性物质的潜力。近年来随着对海洋微生物研究的深入,从海洋真菌中发现了越来越多的具有抗肿瘤活性且结构新颖的天然产物。这些海洋真菌有的分离自海水、海泥或海洋沉积物,有的来自于海洋生物体。本文综述了近几年来从海洋真菌中分离得到的抗肿瘤天然产物的研究状况。     

海洋真菌抗污损活性天然产物研究

黏附于海洋船舶或人工设施表面的污损生物给人类海洋生产活动与生态环境带来诸多不利影响.将具有抗污损活性的化合物开发成防污涂料是目前防治海洋生物污损的最常用手段之一.而大量传统有机金属防污剂因其严重毒副作用被禁用,亟须开发高效、环境友好型抗污损涂料.海洋真菌能够产生大量结构新颖、作用机制独特的高效、低毒/无毒抗污损活性次级...     

Mycotoxin production from fungi isolated from grapes

AIMS: In order to assess the potential for producing mycotoxins, fungi were isolated from wine producing grapes. METHODS AND RESULTS: The isolates were identified and Penicillium expansum, the most well recognized mycotoxin producer, was analysed for mycotoxin production by TLC. Many of the strains produced patulin and/or citrinin, often depending on whether they were grown on a grape or yeast extract sucrose media. CONCLUSION: Citrinin was produced by all strains grown in the yeast extract sucrose medium, but only one strain (from 51) was able to produce this compound in grape juice medium. Patulin was produced in the yeast extract medium by 20 strains and in grape juice medium by 33 strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of mycotoxins in wine producing grapes is discussed. Grapes contamination with patulin seems not to contribute to wine contamination, and no ochratoxin producing fungi was identified.     

Toxic fungi isolated from tall fescue

Summary Extracts of cold-grown common molds isolated from tall fescue forage produce toxic effects on rabbit skin and hemorrhagic death in mice. A mixture ofCladosporium cladosporioides andFusarium nivale produced ruminal atony in a sheep. The clinical findings in the sheep show some similarity to those of cattle on toxic fescue pastures. Further work to determine the role of fungal toxins in the etiology of fescue foot in cattle is underway.     

Cellulolytic fungi isolated from wood shavings

Three species of fungi namely Fusarium roseum USDB 0005, Curvularia lunata var. aeria USDB 0006 and Trichoderma hamatum USDB 0008, and a sterile isolate were found growing on wood shavings. Both F. roseum USDB 0005 and C. lunata var. aeria USDB 0006 and the sterile isolate were weakly cellulolytic while T. hamatum USDB 0008 was strongly cellulolytic. Enzyme assays showed that T. hamatum USDB 0008 produced all the three components (exoglucanase, endoglucanase and B-glucosidase) of the cellulase complex. The enzymatic activity of this strain is compared to that of cellulolytic strains isolated from other wood sources.     

Keratinophilic fungi isolated from antarctic soil

In the present study, 10 soil samples were collected aseptically from an equal number of areas of the Antarctic in the zone occupied by the 1986–1987 Italian expedition for research on keratinophilic fungi.Of particular interest was the isolation of a pathogenic fungus, Microsporum gypseum, from two sites in the base camp occupied by men and by skuas. Trichophyton terrestre was isolated from a site in which people worked and through which penguins and skuas passed.The most widespread fungal species were members of the genus Chrysosporium. Some of these species were isolated but not identified and this part of the study was still be completed.Another significant finding was the absence of fungi in one sample, while in another the widespread and abundant growth in all the seeded dishes of a single species of Chrysosporium.Other species in genera of general diffusion in many environments were also isolated : Aspergillus spp., Malbranchea sp., Mycelia sterilia spp., Paecilomyces sp., Penicillium spp. and Scopulariopsis spp.     

The phytate and mineral content of some cereals,cereal products,legumes, legume products,snack bars,and nuts available in New Zealand

Analyses for phytate by an indirect precipitation method and for the minerals calcium (Ca), zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) by atomic absorption spectrophotometry were carried out on 100 foods available in New Zealand. Foods with 1% phytate (dry weight basis) included untoasted muesli, rolled oats, wheat germ, wheat bran, soybean, and some soy products. Most breads contained between 0.35 and 0.60% phytate; legumes on average had 0.62% phytate, as did snack bars. There was a wide variation in Ca and Zn contents: There was a tenfold variation in Ca content among the legume products, whereas there was a seventyfold variation in Zn content among the cereals. The phytate: Zn molar ratio, which is presumed to indicate the biovailability of Zn, was above 20∶1 for two-thirds of the cereals and almost all of the snack bars; it was above 15∶1 for one-third of the breads, almost all of the legumes, and half of the legume products. These high phytate: Zn molar ratios, as well as some Ca: phytate molar ratios above 6∶1, indicate that there might be a reduced biovailability of Zn in many of the foods analyzed in this study.     

Isolation of entomopathogenic fungi from Northern Thailand and their production in cereal grains

Spore productivity in six entomopathogenic fungal strains isolated from insect cadavers at four locations in Chiang Mai province was evaluated in five cereal grains: white-rice, wheat, rye, corn and sorghum. According to sequence analysis of the internal transcribed spacer regions of these isolates, they were closely related to Beauveria bassiana (2 isolates), Metarhizium flavoviride (1 isolate), Metarhizium anisopliae (1 isolate), Paecilomyces lilacinus (1 isolate) and Isaria tenuipes (1 isolate). Among all fungal isolates, the maximum amount of spores (530.0?×?10⁹ conidia/g) was yielded P. lilacinus CMUCDMT02 on sorghum grain followed by white-rice (399.3?×?10⁹ conidia/g). Moreover, the highest number of spore in M. flavoviride was 102.8?×?10⁹ conidia/g sorghum whereas white-rice yielded the greatest amount of spore for B. bassiana CMUCDMF03 (141.0?×?10⁹ conidia/g) after 60?days incubation. The fungal growth rate was found highest in corn for all strains and rye showed the lowest with the exception of P. lilacinus CMUCDMT02 among the tested grains. Spore viability was over 80?% for all isolates that had been inoculated for 60?days. Fungal conidia suspension of P. lilacinus obtained highest virulence against Bactrocera spp. at a concentration of 1?×?10⁶ spore/ml. The strains isolated, exhibited good production of conidia suggesting a promising strategy for the mass production of inoculum as biocontrol agents with low production cost.     

Endophytic fungi isolated from medicinal plants: future prospects of bioactive natural products from Tabebuia/Handroanthus endophytes

Medicinal plants are a rich source of natural products used to treat many diseases; therefore, they are the basis for a new drug discovery. Plants are capable of generating different bioactive secondary metabolites, but a large amount of botanical material is often necessary to obtain small amounts of the target substance. Nowadays, many medicinal plants are becoming rather scarce. For this reason, it is important to point out the interactions between endophytic microorganisms and the host plant, because endophytes are able to produce highly diverse compounds, including those from host plants that have important biological activities. Thence, this review aims at presenting the richness in bioactive compounds of the medicinal plants from Tabebuia and Handroanthus genera, as well as important aspects about endophyte-plant interactions, with emphasis on the production of bioactive compounds by endophytic fungi, which has been isolated from various medicinal plants for such a purpose. Furthermore, bio-prospection of natural products synthesized by endophytes isolated from the aforementioned genera used in traditional medicine could be used to treat illnesses.

     

Toxigenic Corynebacterium ulcerans isolated from a hunting dog and its diphtheria toxin antibody titer

Toxigenic Corynebacterium ulcerans is a zoonotic pathogen that produces diphtheria toxin and causes a diphtheria‐like illness in humans. The organism is known to infect and circulate among dogs, which can then transmit it to humans. Furthermore, previous studies have found that C. ulcerans is carried by wild animals, including game animals. In the present study, we tested hunting and companion dogs for the presence of toxigenic C. ulcerans and succeeded in isolating the bacterium from a hunting dog. Moreover, several hunting dogs had serum diphtheria antitoxin titers that were higher than the titers required for protection in humans, suggesting a history of exposure to toxigenic Corynebacterium strains. Notably, ribotyping, pulsed‐field gel electrophoresis and tox gene sequencing demonstrated that the isolate from the hunting dog clustered with previously characterized C. ulcerans strains isolated from wild animals, as opposed to groups of isolates from humans and companion dogs. Interestingly, the wild animal cluster also contains an isolate from an outdoor breeding dog, which could have formed a bridge between isolates from wild animals and those from companion dogs. The results presented herein provide insight into the mechanism by which the zoonotic pathogen C. ulcerans circulates among wild animals, hunting and companion dogs, and humans.