The genus Eurotium - members of indigenous fungal community in hypersaline waters of salterns

Six different species of the known teleomorphic food-borne xerophilic genus Eurotium were repeatedly isolated in a mycodiversity study of hypersaline waters. At salinities above 17% NaCl, E. amstelodami was detected most consistently, followed by E. repens and E. herbariorum, while E. rubrum, E. chevalieri and a potentially new species, "Eurotium halotolerans", were detected only occasionally at lower salinities. The qualitative secondary metabolite profiles produced by Eurotium spp. from salterns were not different from those of Eurotium spp. from foods and other habitats. Spatiotemporal frequency of occurrence and in vitro determined adaptive ability of propagules to survive prolonged exposure to hypersaline conditions indicate that E. amstelodami, E. herbariorum, and E. repens contribute to the indigenous fungal community in hypersaline water environments, while E. rubrum, E. chevalieri and "E. halotolerans" are only temporal inhabitants of brine at lower salinities.     

Fungal endophytes in green coffee seeds

Green coffee seeds from Colombia, Guatemala, India, Kenya, Papua New Guinea, Puerto Rico and Vietnam were sampled for the presence of fungal endophytes. Stions of surface sterilized seeds were plated on yeast malt agar, and fungal growth was isolated for subsequent DNA extraction and sequencing. Several fungal genera were isolated, including Acremonium, Aspergillus, Eurotium, Fusarium, Gibberella, Penicillium, Pseudozyma and an undescribed clavicipitaceous species. The biological activities that these fungi might be playing in coffee seeds remain unknown, but in other plants some of the genera isolated have been reported to protect against plant pathogens.     

咖啡种子中的内生真菌

Green coffee seeds from Colombia, Guatemala, India, Kenya, Papua New Guinea, Puerto Rico and Vietnam were sampled for the presence of fungal endophytes. Stions of surface sterilized seeds were plated on yeast malt agar, and fungal growth was isolated for subsequent DNA extraction and sequencing. Several fungal genera were isolated, including Acremonium, Aspergillus, Eurotium, Fusarium, Gibberella, Penicillium, Pseudozyma and an undescribed clavicipitaceous species. The biological activities that these fungi might be playing in coffee seeds remain unknown, but in other plants some of the genera isolated have been reported to protect against plant pathogens.     

咖啡种子中的内生真菌

Green coffee seeds from Colombia, Guatemala, India, Kenya, Papua New Guinea, Puerto Rico and Vietnam were sampled for the presence of fungal endophytes. Stions of surface sterilized seeds were plated on yeast malt agar, and fungal growth was isolated for subsequent DNA extraction and sequencing. Several fungal genera were isolated, including Acremonium, Aspergillus, Eurotium, Fusarium, Gibberella, Penicillium, Pseudozyma and an undescribed clavicipitaceous species. The biological activities that these fungi might be playing in coffee seeds remain unknown, but in other plants some of the genera isolated have been reported to protect against plant pathogens.     

Distribution of sterigmatocystin in filamentous fungi

During the last 50y, the carcinogenic mycotoxin sterigmatocystin (ST) has been reported in several phylogenetically and phenotypically different genera: Aschersonia, Aspergillus, Bipolaris, Botryotrichum, Chaetomium, Emericella, Eurotium, Farrowia, Fusarium, Humicola, Moelleriella, Monocillium and Podospora. We have reexamined all available strains of the original producers, in addition to ex type and further strains of each species reported to produce ST and the biosynthetically derived aflatoxins. We also screened strains of all available species in Penicillium and Aspergillus for ST and aflatoxin. Six new ST producing fungi were discovered: Aspergillus asperescens, Aspergillus aureolatus, Aspergillus eburneocremeus, Aspergillus protuberus, Aspergillus tardus, and Penicillium inflatum and one new aflatoxin producer: Aspergillus togoensis (=Stilbothamnium togoense). ST was confirmed in 23 Emericella, four Aspergillus, five Chaetomium, one Botryotrichum and one Humicola species grown on a selection of secondary metabolite inducing media, and using multiple detection methods: HPLC-UV/Vis DAD, - HRMS and - MS/MS. The immediate precursor for aflatoxin, O-methylsterigmatocystin was found in Chaetomium cellulolyticum, Chaetomium longicolleum, Chaetomium malaysiense and Chaetomium virescens, but aflatoxin was not detected from any Chaetomium species. In all 55 species, representing more than 11 clades throughout the Pezizomycotina, can be reliably claimed to be ST producers and 13 of these can also produce aflatoxins. It is not known yet whether the ST/aflatoxin pathway has been developed independently 11 times, or is the result of partial horizontal gene transfer.     

Unusual fungal niches

Fungi are found in all aerobic ecosystems, colonizing a diversity of substrates and performing a wide diversity of functions, some of which are not well understood. Many spices of fungi are cosmopolitan and generalists or habitats. Unusual fungal niches are habitats where extreme conditions would be expected to prevent the development of a mycobiota. In this review we describe five unusual fungal habitats in which fungi occupy poorly understood niches: Antarctic dry valleys, high Arctic glaciers, salt flats and salterns, hypersaline microbial mats and plant trichomes. Yeasts, black yeast-like fungi, melanized filamentous species as well as representatives of Aspergillus and Penicillium seem to be dominant among the mycobiota adapted to cold and saline niches. Plant trichomes appear to be a taxa. The advent of new sequencing technologies is helping to elucidate the microbial diversity in many ecosystems, but more studies are needed to document the functional role of fungi in the microbial communities thriving in these unusual environments.     

Fungal life in the extremely hypersaline water of the Dead Sea: first records.

The first report, to our knowledge, on the occurrence of filamentous fungi in the hypersaline (340 g salt l-1) Dead Sea is presented. Three species of filamentous fungi from surface water samples of the Dead Sea were isolated: Gymnascella marismortui (Ascomycota), which is described as a new species, Ulocladium chlamydosporum and Penicillium westlingii (Deuteromycota). G. marismortui and U. chlamydosporum grew on media containing up to 50% Dead Sea water. G. marismortui was found to be an obligate halophile growing optimally in the presence of 0.5-2 M NaCl or 10 30% (by volume) of Dead Sea water. Isolated cultures did not grow on agar media without salt, but grew on agar prepared with up to 50% Dead Sea water. This suggests that they may be adapted to life in the extremely stressful hypersaline Dead Sea.     

Mites and fungi in heavily infested stores in the Czech Republic

Toxigenic and allergen-producing fungi represent a serious hazard to human food and animal feed safety. Ninety-four fungal species were isolated from mite-infested samples of seeds taken from Czech seed stores. Fungi were isolated from the surface of four kinds of seeds (wheat, poppy, lettuce, and mustard) and from the gut and external surface of five species of mites (i.e., Acarus siro L., 1758, Caloglyphus rhizoglyphoides (Zachvatkin, 1973), Lepidoglyphus destructor (Schrank, 1781), Tyrophagus putrescentnae (Schrank, 1781) and Cheyletus malaccensis Oudemans 1903) separately. Multivariate analysis of fungi complex composition showed that the frequency of fungal was species significantly influenced by the kind of seed. Fungal frequencies differed between mites gut and exoskeleton surface and between the surfaces of mites and seeds. Three groups of fungal species were recognized: 1) mite surface-associated fungi: Penicillium brevicompactum, Alternaria alternata, and Aspergillus versicolor; 2) mite surface- and seed-associated fungi: Aspergillus niger, Penicillium crustosum, Penicillium aurantiogriseum, Penicillium chrysogenum, and Aspergillus flavus; and 3) seed-associated fungi: Cladosporium herbarum, Mucor dimorphosporus f. dimorphosporus, Botrytis cinerea, Penicillium griseofulvum, and Eurotium repens. Mite-carried species of microfungi are known to produce serious mycotoxins (e.g., aflatoxin B1, cyclopiazonic acid, sterigmatocystin, ochratoxin A, and nephrotoxic glycopeptides) as well as allergen producers (e.g., A. alternata and P. brevicompactum). Storage mites may play an important role in the spread of some medically hazardous micromycetes. In addition, these mite-fungi associations may heighten the risk of occurrence of mycotoxins in food and feed stuffs and cause mixed contamination by fungal and mite allergens.     

Seed-borne fungi of date-palm,Phoenix dactylifera L. from Saudi Arabia

Six different varieties of date-palm viz. Sukhari, Saggae, Rotana, Kholasi, Rashoodia and Nabtat Ali, were screened for seed-borne fungi. Eleven species belonging to nine different genera of fungi were isolated. The genera isolated were Alternaria, Eurotium, and Fusarium (two species), Aspergillus, Drechslera, Penicillium, Rhizopus, and Curvularia (one species each). This is the first record of seed-borne fungi from Phoenix dactyliera L. in Saudi Arabia.     

南极乔治王岛的丝状真菌

本文报道从南极乔治王岛26个样品中分离到60株丝状真菌,其中6个样品未分离到任何真菌,经初步鉴定有8属10个种。根据本次温度实验和该地寒冷的气候,只有桔灰青霉(Penicillium aurantiogriseum Dierckx),大毛霉Mucor mucedo(L.)Fres.)和毡状金孢霉(chrysosporium pannorum(Link)Hughes)在本地能生长繁殖。其中毡状金孢霉占明显优势。     

Molecular identification of Aspergillus and Eurotium species isolated from rice and their toxin-producing ability

Thirty milled rice samples were collected from retailers in 4 provinces of Malaysia. These samples were evaluated for Aspergillus spp. infection by direct plating on malt extract salt agar (MESA). All Aspergillus holomorphs were isolated and identified using nucleotide sequences of ITS 1 and ITS 2 of rDNA. Five anamorphs (Aspergillus flavus, A. oryzae, A. tamarii, A. fumigatus and A. niger) and 5 teleomorphs (Eurotium rubrum, E. amstelodami, E. chevalieri, E. cristatum and E. tonophilum) were identified. The PCR-sequencing based technique for sequences of ITS 1 and ITS 2 is a fast technique for identification of Aspergillus and Eurotium species, although it doesn't work flawlessly for differentiation of Eurotium species. All Aspergillus and Eurotium isolates were screened for their ability to produce aflatoxin and ochratoxin A (OTA) by HPLC and TLC techniques. Only A. flavus isolate UPM 89 was able to produce aflatoxins B1 and B2.     

遗址木构件有害真菌的快速测定方法

介绍了1种快速测定遗址木构件有害真菌的方法:用孢子菌丝悬浮液直接接种于供试木块上,培养4d,即可确定其侵染性;培养8d,即可确定其侵染力。应用该方法成功地测定了灰绿曲霉(Aspergillus glau-cus)、黑曲霉(Aspergillus niger)、枝孢霉(Cladosporiumsp.)、顶青霉(Penicillium corylophilum)、柑桔青霉(Penicilliumcitrinum)、团青霉(Penicillium commune)、黄曲霉(Aspergillus flavus)、微紫青霉(Penicilliumjanthinellum)、总状毛霉(Mucor racemosus)、绿木霉(Trichoderma viride)等10种真菌的侵染性和侵染力。     

Antifungal activity of volatile compounds generated by essential oils against fungi commonly causing deterioration of bakery products

AIMS: To investigate the volatile fractions of 16 essential oils for activity against the more common fungi causing spoilage of bakery products, Eurotium amstelodami, E. herbariorum, E. repens, E. rubrum, Aspergillus flavus, A. niger and Penicillium corylophilum. METHODS AND RESULTS: The study applied 50 microl of pure essential oils in a sterilized filter paper, were carried out at pH 6 and at different water activity levels (0.80-0.90). First, a wheat flour based agar medium was used, where cinnamon leaf, clove, bay, lemongrass and thyme essential oils where found to totally inhibit all microorganisms tested. These five essential oils were then tested in sponge cake analogues, but the antifungal activity detected was much more limited. CONCLUSION: Five essential oils showed potential antifungal capacity against all species tested, over a wide range of water availability. Their activity, however, seems to be substrate-dependent. More research is needed to make them work in real bakery products, as in the preliminary study limited effectiveness was found. SIGNIFICANCE AND IMPACT OF THE STUDY: The potential of the cinnamon leaf, clove, bay, lemongrass and thyme essential oils against species belonging to Eurotium, Aspergillus and Penicillium genus has been demonstrated.     

Halotolerant and halophilic fungi

Extreme environments have for long been considered to be populated almost exclusively by prokaryotic organisms and therefore monopolized by bacteriologists. Solar salterns are natural hypersaline environments characterized by extreme concentrations of NaCl, often high concentrations of other ions, high uv irradiation and in some cases extremes in pH. In 2000 fungi were first reported to be active inhabitants of solar salterns. Since then many new species and species previously known only as food contaminants have been discovered in hypersaline environments around the globe. The eukaryotic microorganism most studied for its salt tolerance is Saccharomyces cerevisiae. However, S. cerevisiae is rather salt sensitive and not able to adapt to hypersaline conditions. In contrast, some species like Debaryomyces hansenii, Hortaea werneckii, and Wallemia ichthyophaga have been isolated globally from natural hypersaline environments. We believe that all three are more suitable model organisms to study halotolerance in eukaryotes than S. cerevisiae. Furthermore, they belong to different and distant taxonomic groups and have developed different strategies to cope with the same problems of ion toxicity and loss of water.     

Associated mycoflora of rye bread

F. Lund, O. Filtenborg, S. Westall And J.C. Frisvad. 1996. Penicillium roqueforti (27%), P. corylophilum (20%) and Eurotium (15%) made up the important mycoflora associated with rye bread on 3425 identified fungi isolates. These fungi were dominant as spoilers of packaged rye bread in almost every month of a 4 year investigation. Penicillium decumbens (3%), Paecilomyces variotii (8%) and Aspergillus flavus (5%) were found more rarely, but were the major species found over periods of a few months. Penicillium commune (5%), P. Solitum (4%), A. niger (4%) and Mucor species (2%) were a constant, but small, part of the mycoflora of rye bread. Identification of the fungi in the production environmentl in a rye bread factory showed the locality of potential contamination sources. Eliminationl of the contmination sources lby improved cleaning and disinfection procedures quickly resulted in a significant reduction in the frequency of mould growth in the packaged rye bread.     

Identification of volatile markers for indoor fungal growth and chemotaxonomic classification of Aspergillus species

Microbial volatile organic compounds (MVOCs) were collected in water-damaged buildings to evaluate their use as possible indicators of indoor fungal growth. Fungal species isolated from contaminated buildings were screened for MVOC production on malt extract agar by means of headspace solid-phase microextraction followed by gas chromatography-mass spectrometry (GC-MS) analysis. Some sesquiterpenes, specifically derived from fungal growth, were detected in the sampled environments and the corresponding fungal producers were identified. Statistical analysis of the detected MVOC profiles allowed the identification of species-specific MVOCs or MVOC patterns for Aspergillus versicolor group, Aspergillus ustus, and Eurotium amstelodami. In addition, Chaetomium spp. and Epicoccum spp. were clearly differentiated by their volatile production from a group of 76 fungal strains belonging to different genera. These results are useful in the chemotaxonomic discrimination of fungal species, in aid to the classical morphological and molecular identification techniques.     

三株散囊菌发酵茶叶的初步研究

散囊菌属真菌(Eurotium spp.)能赋予发酵茶独特的口感和香味。本研究利用前期从广西某六堡茶中筛选并鉴定的三株散囊菌属真菌Aspergillus chevalieri E2、Aspergillus chevalieri E3与Aspergillus cristatus E6,探讨在不同温度下以优化察氏液体培养基培养的生长状况,发酵前不同灭菌条件下的茶叶品质,以及所得茶汤中茶多酚含量、总抗氧化能力和DPPH·自由基清除能力。结果显示:三株真菌在优化的察氏液体培养基中31℃～34℃下都能良好生长。茶叶发酵温度为28℃,三株真菌在发酵初始含水量为20%以上生长良好,其中E3和混合发酵组的生长速度最快。E2在茶叶表面生长出大量金黄色子囊果以及大量浅绿色分生孢子梗; E3几乎只有浅绿色分生孢子梗; E6几乎只有金黄色子囊果。发酵茶叶制作的茶汤内茶多酚含量比未发酵低,抗氧化性指标也有所下降,说明本实验真菌发酵促进了茶内抗氧化物质的氧化。本研究对源于六堡茶不同散囊菌属真菌的茶叶发酵有重要参考价值。     

Environmental factors and preservatives affect carbon utilization patterns and niche overlap of food spoilage fungi

Nutrient assimilation by two mycotoxigenic spoilage fungi (Penicillium verrucosum, Aspergillus ochraceus) and four other food spoilage fungi (Penicillium coryolophilum, P. roqueforti, Cladosporium herbarum, Eurotium repens), of 32 key C-sources in wheat bread were examined in relation to abiotic factors of water availability, pH, temperature and the presence/absence of a preservative, potassium sorbate. These studies were to understand the relative potential co-existence, nutritional partitioning and niche exclusion in bread-based matrices. The niche size decreased significantly with decrease in water availability, temperature and pH. There were also significant interactive effects between pH and the preservative. The data were used to determine the niche overlap indices (NOI) of competing fungi relative to the two ochratoxigenic species. These showed that P. verrucosum and A. ochraceus were nutritionally dominant over the other species. The NOIs showed that potential co-existence and/or niche exclusion was influenced by environmental factors. Overall, the addition of the preservative increased the interspecific competition for nutrients. The level of co-existence and nutritional partitioning was significantly modified by abiotic factors, and this can help explain the dominance of specific fungal species in food matrices. This approach could also be useful for understanding competitiveness and dominance of fungal species in other ecosystems, especially in relation to impacts of abiotic and biotic factors.     

杜比亚蟑螂共生真菌次生代谢产物及其生物活性

为探究杜比亚蟑螂体内共生真菌种类,测定共生真菌次生代谢产物的抑菌活性和抗氧化活性,筛选出具有抗菌和抗氧化活性的菌株,本研究采用组织块分离法分离杜比亚蟑螂体内的共生真菌,通过形态学和分子生物学相结合的方法对分离到的共生真菌进行鉴定;分别采用薄层层析-生物自显影法和DPPH法测定共生真菌次生代谢产物的抗细菌活性和抗氧化活性。结果表明,从杜比亚蟑螂体内共分离鉴定得到5种不同的共生真菌,主要分布于青霉属(1株)、曲霉属(3株)和聚孢霉属(1株)。活性测定的结果表明,菌株Bdf-2、Bdf-4和Bdf-5表现出较好的抗菌活性,且菌液提取物的抗菌活性要强于菌丝。Bdf-1,Bdf-2和Bdf-3菌液次生代谢产物表现出抗氧化活性,IC 50值分别为0.26 mg/mL、2.20 mg/mL和0.75 mg/mL。杜比亚蟑螂共生真菌以青霉属和曲霉属为主,且具有抗菌和抗氧化活性的次生代谢产物主要分布于菌液中。     

Mycotoxin Producing Potential of Fungi Associated with Dry Shrimps

Among 114 fungi isolated from 20 dry shrimp samples, 27 isolates were capable of producing mycotoxins. Aspergillus and Penicillium were-the-predominant fungi. Two of 3 Aspergillus flavus could produce aflatoxin B₁ and G₁ on yeast extract sucrose medium and on surface sterilized dry shrimps. For other toxigenic species, toxicity was found mostly in the chloroform extracts of cultures. Visibly mouldy dry shrimps had significantly higher moisture content than the non-mouldy ones. Most of the fungi were isolated from mouldy samples.