Ochraceus Group Research Articles

Toxic Indoor Air Is a Potential Risk of Causing Immuno Suppression and Morbidity-A Pilot Study.

We aimed to establish an etiology-based connection between the symptoms experienced by the occupants of a workplace and the presence in the building of toxic dampness microbiota. The occupants (5/6) underwent a medical examination and urine samples (2/6) were analyzed by LC-MS/MS for mycotoxins at two time-points. The magnitude of inhaled water was estimated. Building-derived bacteria and fungi were identified and assessed for toxicity. Separate cytotoxicity tests using human THP-1 macrophages were performed from the office’s indoor air water condensates. Office-derived indoor water samples (n = 4/4) were toxic to human THP-1 macrophages. Penicillium, Acremonium sensu lato, Aspergillus ochraceus group and Aspergillus section Aspergillus grew from the building material samples. These colonies were toxic in boar sperm tests (n = 11/32); four were toxic to BHK-21 cells. Mycophenolic acid, which is a potential immunosuppressant, was detected in the initial and follow-up urine samples of (2/2) office workers who did not take immunosuppressive drugs. Their urinary mycotoxin profiles differed from household and unrelated controls. Our study suggests that the presence of mycotoxins in indoor air is linked to the morbidity of the occupants. The cytotoxicity test of the indoor air condensate is a promising tool for risk assessment in moisture-damaged buildings.

Predictive Modeling and Validation on Growth, Production of Asexual Spores and Ochratoxin A of Aspergillus Ochraceus Group under Abiotic Climatic Variables.

This study aimed to generate predictive models for growth, sporulation, and ochratoxin A (OTA) production under abiotic climatic variables, including temperatures (15–35 °C) and water activity levels (0.99–0.90 aw) by Aspergillus ochraceus group. The data were divided into three sets: one for training, one for testing, and the third one for model validation. Optimum growth occurred at 0.95 aw and 25 °C and 0.95 aw and 30 °C for A. westerdijkiae and A. steynii, respectively. Significantly improved A. westerdijkiae and A. steynii spore production occurred at 0.95 aw and 20 °C and 0.90 aw and 35 °C, respectively. A. steynii and A. westerdijkiae produced the majority of OTA at 35 °C and 0.95 aw and 25–30 °C at 0.95–0.99 aw, respectively. The accuracy of the third-order polynomial regression model reached 96% in growth cases, 94.7% in sporulation cases, and 90.9% in OTA production cases; the regression coefficients (R2) ranged from 0.8819 to 0.9978 for the Aspergillus ochraceus group. A reliable agreement was reached between the predicted and observed growth, sporulation, and OTA production. The effects of abiotic climatic variables on growth, sporulation, and OTA production of A. ochraceus group have been effectively defined, and the models generated were responsible for adequately predicted and validated models against data from other strains within A. ochraceus group that had been published in the literature under the current treatments. These models could be successfully implemented to predict fungal growth and OTA contamination on food matrices for these strains under these conditions.

Fungal levels in houses in the Fukushima Daiichi Nuclear Power Plant evacuation zone after the Great East Japan Earthquake

ABSTRACTResidences located within 20 km of the damaged Fukushima Daiichi Nuclear Power Plant were evacuated shortly after the Great East Japan Earthquake. The levels of airborne and surface fungi were measured in six houses in the evacuation zone in August 2012 and February 2013. Airborne fungal levels in all of the houses in the summer were higher than the environmental standard levels for residential houses published in Architectural Institute of Japan (>1000 colony-forming units [CFU]/m3). In two houses whose residents rarely returned to visit, fungal levels were extremely high (>52,000 CFU/m3). Although fungal levels in the winter were much lower than those in the summer, they were still higher than environmental standard levels in several houses. Indoor fungal levels were significantly inversely related to the frequency with which residents returned, but they were not correlated with the air exchange rates, temperature, humidity, or radiation levels. Cladosporium spp. and Penicillium spp. were detected in every house. Aspergillus section Circumdati (Aspergillus ochraceus group) was also detected in several houses. These fungi produced ochratoxin A and ochratoxin B, which have nephrotoxic and carcinogenic potential. The present study suggests that further monitoring of fungal levels is necessary in houses in the Fukushima Daiichi Nuclear Power Plant evacuation zone, and that some houses may require fungal disinfection.Implications: The results suggest that residents’ health could be at risk owing to the high levels of airborne fungi and toxic fungi Aspergillus section Circumdati. Therefore, monitoring and decontamination/disinfection of fungi are strongly recommended before residents are allowed to return permanently to their homes. In addition, returning to home with a certain frequency and adequate ventilation are necessary during similar situations, e.g., when residents cannot stay in their homes for a long period, because fungal levels in houses in the Fukushima Daiichi Nuclear Power Plant evacuation zone were inversely correlated with the frequency with which residents returned to visit their houses.

Ochratoxin production and taxonomy of the yellow aspergilli (Aspergillus section Circumdati)

Aspergillus section Circumdati or the Aspergillus ochraceus group, includes species with rough walled stipes, biseriate conidial heads, yellow to ochre conidia and sclerotia that do not turn black. Several species are able to produce mycotoxins including ochratoxins, penicillic acids, and xanthomegnins. Some species also produce drug lead candidates such as the notoamides. A polyphasic approach was applied using morphological characters, extrolite data and partial calmodulin, β-tubulin and ITS sequences to examine the evolutionary relationships within this section. Based on this approach the section Circumdati is revised and 27 species are accepted, introducing seven new species: A. occultus, A. pallidofulvus, A. pulvericola, A. salwaensis, A. sesamicola, A. subramanianii and A. westlandensis. In addition we correctly apply the name A. fresenii (≡ A. sulphureus (nom. illeg.)). A guide for the identification of these 27 species is provided. These new species can be distinguished from others based on morphological characters, sequence data and extrolite profiles. The previously described A. onikii and A. petrakii were found to be conspecific with A. ochraceus, whilst A. flocculosus is tentatively synonymised with A. ochraceopetaliformis, despite extrolite differences between the two species. Based on the extrolite data, 13 species of section Circumdati produce large amounts of ochratoxin A: A. affinis, A. cretensis, A. fresenii, A. muricatus, A. occultus, A. ochraceopetaliformis (A. flocculosus), A. ochraceus, A. pseudoelegans, A. pulvericola, A. roseoglobulosus, A. sclerotiorum, A. steynii and A. westerdijkiae. Seven additional species produce ochratoxin A inconsistently and/or in trace amounts: A. melleus, A. ostianus, A. persii, A. salwaensis, A. sesamicola, A. subramanianii and A. westlandensis. The most important species regarding potential ochratoxin A contamination in agricultural products are A. ochraceus, A. steynii and A. westerdijkiae.

Mycobiota of cocoa: From farm to chocolate

The present work was carried out to study the mycobiota of cocoa beans from farm to chocolate. Four hundred and ninety-four samples were analyzed at various stages of cocoa processing: (i) primary stage at the farm (fermentation, drying, and storage), (ii) secondary stage at processing (testa, nibs, liquor, butter, cake and powder) and (iii) the final chocolate product (dark, milk, white and powdered) collected from retail outlets. Direct plating or dilution plating on Dichloran 18% Glycerol agar were used for cocoa beans and processed product analyses, respectively. Fungi were isolated and identified using different keys of identification. The largest numbers and diversity of fungi were observed in the samples collected at the farm, especially during drying and storage. The species with the highest occurrence among samples were: Absidia corymbifera, Aspergillus sp. nov., A. flavus, Penicillium paneum and yeasts. A total of 1132 potentially toxigenic fungi were isolated from the following species or species groups: A. flavus, Aspergillus parasiticus, Aspergillus nomius, Aspergillus niger group, Aspergillus carbonarius and Aspergillus ochraceus group. The highest percentage of toxigenic fungi was found at the drying and storage stages. The industrial processing reduced the fungal contamination in all fractions and no fungi were found in the final chocolate products. The knowledge of which fungi are dominant at each processing stage of cocoa provides important data about their ecology. This understanding leads to a reduction in fungal spoilage and mycotoxin production in this product.

Volatile Compounds of Aspergillus Strains with Different Abilities To Produce Ochratoxin A

Volatile compounds emitted by Aspergillus strains having different abilities to produce ochratoxin A were investigated. Thirteen strains of Aspergillus ochraceus, three belonging to the A. ochraceus group, and eight other species of Aspergillus were examined for their abilities to produce volatile compounds and ochratoxin A on a wheat grain medium. The profiles of volatile compounds, analyzed using SPME, in all A. ochraceus strains, regardless of their toxeginicity, were similar and comprised mainly of 1-octen-3-ol, 3-octanone, 3-octanol, 3-methyl-1-butanol, 1-octene, and limonene. The prevailing compound was always 1-octen-3-ol. Mellein, which forms part of the ochratoxin A molecule, was found in both toxigenic and nontoxigenic strains. Volatile compounds produced by other Aspergillus strains were similar to those of A. ochraceus. Incubation temperatures (20, 24, and 27 degrees C) and water content in the medium (20, 30, and 40%) influenced both volatile compounds formation and ochratoxin A biosynthesis efficiency, although conditions providing the maximum amount of volatiles were different from those providing the maximum amount of ochratoxin A. The pattern of volatiles produced by toxigenic A. ochraceus strains does not facilitate their differentiation from nontoxigenic strains.

On ochratoxin A and fungal flora in Polish cereals from conventional and ecological farms. Part 2: Occurrence of ochratoxin A and fungi in cereals in 1998

Over 200 samples of Polish cereal grain from the 1998 harvest obtained from conventional and ecological farms were investigated for the presence of ochratoxin A and for contamination by microscopic fungi. The frequency of contamination of rye and barley grains from conventional and ecological farms was similar in most cases; it varied from nearly 5 to 12%, respectively, for both types of farming. However, in samples from ecological farms, higher maximum concentrations of ochratoxin A were observed (35 μg kg-1, overall range 1.4–35.3 μg kg-1) for both cereals rye and barley in comparison with rye and barley from conventional farms (maximum levels of 8.8 and 9.7 μg kg-1, respectively). However, wheat grain from the conventional farms showed ochratoxin A concentrations in a very wide range from 0.6 to 1024 μg kg-1 and the average frequency of contaminated samples was about 48%. In contrast, in wheat samples from ecological farming, the presence of ochratoxin A ranged from 0.8 to 1.6 μg kg-1 (mean 1.2 μg kg-1) and the frequency of contamination was 23%. From samples containing detectable amounts of ochratoxin A, fungi producing ochratoxin A under laboratory conditions were isolated. They were classified as belonging to the species Penicillium cyclopium, P. viridicatum, Aspergillus ochraceus group, A. glaucus> and A. versicolor. Penicilliumstrains—species known to be producers of ochratoxin A—were isolated from 71% of the samples in 28% of samples, only Aspergillus strains (species known to be producers of this mycotoxin) were noted. These results have been compared with those obtained in 1997.

Ochratoxin production by the Aspergillus ochraceus group and Aspergillus alliaceus.

Ochratoxin A is a toxic and carcinogenic fungal secondary metabolite; its presence in foods is increasingly regulated. Various fungi are known to produce ochratoxins, but it is not known which species produce ochratoxins consistently and which species cause ochratoxin contamination of various crops. We isolated fungi in the Aspergillus ochraceus group (section Circumdati) and Aspergillus alliaceus from tree nut orchards, nuts, and figs in California. A total of 72 isolates were grown in potato dextrose broth and yeast extract-sucrose broth for 10 days at 30 degrees C and tested for production of ochratoxin A in vitro by high-pressure liquid chromatography. Among isolates from California figs, tree nuts, and orchards, A. ochraceus and Aspergillus melleus were the most common species. No field isolates of A. ochraceus or A. melleus produced ochratoxin A above the level of detection (0.01 microg/ml). All A. alliaceus isolates produced ochratoxin A, up to 30 microg/ml. We examined 50,000 figs for fungal infections and measured ochratoxin content in figs with visible fungal colonies. Pooled figs infected with A. alliaceus contained ochratoxin A, figs infected with the A. ochraceus group had little or none, and figs infected with Penicillium had none. These results suggest that the little-known species A. alliaceus is an important ochratoxin-producing fungus in California and that it may be responsible for the ochratoxin contamination occasionally observed in figs.

Occurrence of itraconazole-tolerant micromycetes in the soil and food products.

Unexpected pathogens from the environment represent considerable risk for humans with impaired health. We examined the occurrence of itraconazole tolerant micromycetes in soil and in maize products. Five concentrations of itraconazole (2.5-12.5 micrograms/mL) selected according to known treatment schedules for human patients were incorporated into Sabouraud agar with chloramphenicol and Rose Bengal and diluted samples were inoculated onto the agar surface. After 7-d growth at 22 degrees C colonies of Alternaria sp., Aspergillus clavatus, A. glaucus group, A. flavus, A. fumigatus, A. niger group, A. ochraceus group, A. ochraceus, Chaetomium sp., Cladosporium cladosporioides, Cylindrocarpon sp., Doratomyces sp., Fusarium sp., F. moniliforme, F. oxysporum, F. solani, F. subglutinans, Marianaea elegans, Mortierella sp., Mucor sp., Myrothecium sp., Penicillium sp., Rhizopus sp., Scopulariopsis brevicaulis, Sepedonium sp., Stachybotrys chartarum, Stemphylium sp., Torula humicola and Trichoderma viride were isolated.

Mycotoxin production by molds isolated from ‘Greek-style’ black olives

Seventeen mold strains were isolated from ‘Greek-style’ black olives produced in Morocco. Eight of these isolates were identified as Aspergillus flavus, seven as Aspergillus petrakii, and two as Aspergillus ocharaceus Wilhelm. The A. flavus strains were tested for production of aflatoxins B 1, B 2, G 1, and G 2; and A. ochraceus and A. petrakii strains were tested for production of ochratoxin, penicillic acid, patulin, and citrinin. The organisms were tested for mycotoxin production on five different substrates, including rice powder-corn steep agar, autoclaved rice, yeast-extract sucrose broth (YES), potato dextrose agar (PDA), and fresh olive paste. All strains of A. flavus produced aflatoxins on all substrates except olive paste and PDA. In PDA, only two strains produced Aflatoxin B 1. Five A. ochraceus group isolates produced penicillic acid on one or more of the substrates, but only two out of the five produced penicillic acid on olive paste. None produced ochratoxin, patulin or citrinin. Quantities of aflatoxin B 1 produced in rice ranged from 5 to 14 μg/g of rice, and of penicillic acid 15–32 μg/g of rice. In olive paste, the concentrations of penicillic acid were 11.4 and 30.2 μg/g. Biological toxicity of extracts of mold cultures was confirmed using chicken embryos and a microbiological test. Crude extracts of cultures were also tested for mutagenicity using the Salmonella mutagenicity (Ames) Test, and some gave positive mutagenic responses.

輸入生コーヒー豆のマイコトキシン汚染調査と毒素産生菌について

The survey of 22 commercial samples of imported green coffee beans for aflatoxins and ochratoxin has been conducted in 1982-1983. Ochratoxin A was detected in 4 samples at a level of 9.9-46μg/kg but all samples analyzed were negative for aflatoxins. Major contaminants of the samples were Aspergillus glaucus group, A, niger group, A. flavus group, A. ochraceus group and members of the Mucorales. Among the contaminants, the ability of A, flavus and A, ochraceus isolates to produce the mycotoxins was examined. Particularly, 9 isolates of A. ochraceus group produced high levels of ochratoxin A on artificial polished rice and ground coffee media (yields of ochratoxin A: 48.3-750μg/g on rice and 8.06-130μg/g on coffee, respectively). Addition of caffeine (0.1-1.0%) on MY-20 agar medium in a Petri dish resulted the delayed growth of A. ochraceus strain S-235-100, a representative isolate from the green coffee beans, but had little effect on its ochratoxin production. On the basis of the results obtained in this study, it is apparent that green coffee beans might be susceptible to A, ochraceus infection and subsequent ochratoxin production.

Hazardous species ofAspergillus ochraceus group in the air of working environments at Mysore

Species of theAspergillus ochraceus group were most abundant in the air of a coffee curing works of the seventeen environments studied at Mysore. They also occurred in large numbers in coffee dust, husk samples, sorghum and paddy. Incubating at room temperature (20–25°C) was found most suitable for enumeration of these species. Only 6.6% of the air-borne isolates of the group produced ochratoxin-A. A. ochraceus was the most common species of the group isolated from air and also yielded a greater proportion of toxic isolates.

TheAspergillus OchraceusGroup: Two New Species from Western Soils and a Synoptic Key

Two new species in the Aspergillus ochraceus group are described and compared to related taxa. Aspergillus bridgeri, from soils collected in a native community dominated by Atriplex gardneri in Wyoming, somewhat resembles A. elegans and A. lanosus, but differs in cultural and morphological details. Aspergillus campestris, from a native prairie in northern North Dakota, resembles A. dimorphicus in having metulae that are up to 35-45 im long, but is a more restricted form with yellow conidial heads, taller conidiophores, occasionally septate metulae, and ellipsoidal conidia. A synoptic key is presented as an aid to identification of species in the A. ochraceus group-an assemblage which has increased considerably since 1965 and currently embraces 15 species. Brief descriptions of the species accompany the key along with distributional and ecological analyses prepared from species lists in more than 130 published surveys.

The Aspergillus ochraceus Group: Two New Species from Western Soils and a Synoptic Key

The Aspergillus ochraceus Group: Two New Species from Western Soils and a Synoptic Key

Culture Conditions and Purification Method for Large-scale Production of Ochratoxins by Aspergillus ochraceus

It was found that three of fifty-one strains of A. ochraceus group fungi isolated from green coffee beans produced ochratoxin A (OCT-A). One of these three strains and another isolated from barley produced high levels of OCT-A.Several of the twenty-seven single-spore isolates derived from these two strains showed stable and high production of OCT-A. A 300ml Erlenmeyer flask with 30g of polished rice and 12ml of water was autoclaved, then inoculated with A. ochraceus and incubated for 2 weeks at 25°C. These conditions were optimum for toxin production.The methods for extraction, column chromatography, crystallization, etc. were examined, and suitable procedures to obtain pure ochratoxins from the moldy rice were established. Large amounts of crystalline OCT-A and B were easily obtained.Studies on the bioactivity of OCT-A are in progress.

Production of xanthomegnin and viomellein by species of Aspergillus correlated with mycotoxicosis produced in mice.

By using thin-layer chromatography and infrared spectroscopy, xanthomegnin and viomellein have been isolated and identified from species of the Aspergillus ochraceus group. A correlation was established between the occurrence of these fungal quinones in the fungal cultural products and the ability of these products to induce mycotoxicosis in mice. In addition, a method was employed to estimate the amount of xanthomegnin and viomellein produced by the fungi.

Mycotoxic diseases produced in mice by species of the aspergillus ochraceus group

Twenty-three isolates (identified below by Northern Regional Research Laboratory culture numbers) comprising eight species of the Aspergillus ochraceus group were examined for toxicity in Swiss albino mice fed for 3 wk on diets containing rice cultures of the isolates mixed at 50% concentrations with a commercial purified diet. The histopathological changes produced and a capacity to produce ochratoxin A, penicillic acid or both mycotoxins were the criteria used to assign the isolates to one of five groups. Group I ( A. auricomus NRRL nos 387 and 388, A. petrakii 404, 416 and 4369, A. elegans 4850 and A. alliaceus 1237) included some strains that produced penicillic acid but none produced ochratoxin A and none caused a significant incidence of lesions or deaths. Group II isolates ( A. sclerotiorum 415, 1598 and 4901) did not produce ochratoxin A, but two produced penicillic acid and all caused a 100% death rate, principally with lesions of multifocal hepatic necrosis and fatty change. In group III ( A. alliaceus 315 and 4181), each isolate produced ochratoxin A and all the treated mice died. Renal lesions were consistent with those described for ochratoxicosis A. Group IV isolates ( A. sclerotiorum 5166 and 5170) produced both ochratoxin A and penicillic acid and killed over half of the treated mice. The main hepatic and renal lesions in these mice were necrotizing cholangitis, multifocal hepatic necrosis and degeneration and necrosis of the renal convoluted tubules. The group V isolates ( A. melleus 386 and 5103, A. ostianus 420 and 3524 and A. ochraceus 398, 399, 400, 402 and 410, as well as an isolate of Penicillium viridicatum, Purdue University Strain 66-68-2) did not produce ochratoxin A, but four produced penicillic acid and all caused hepatic and renal lesions identical to those observed with group IV isolates. The hepatic and renal changes observed in the mouse following treatment with either the group IV or group V isolates were similar to those described previously for an isolate of A. ochraceus and for several Indiana isolates of P. viridicatum.

Identification of Osmophilic Aspergillus Isolated from Rice and Their Radio-sensitivity

Osmophilic Aspergillus responsible for spoilage of rice, corn, milo and wheat have been isolated and identified. Fifteen strains were classified as members of the Aspergillus glaucus group, and were subdivided into A. ruber, A. repens, A. mangini, A. chevalieri and A. montevidensis. Nine strains were classified as members of the A. restrictus group, and were subdivided into A. gracilis, A. vitricolae and A. casiellus. The other 7 strains were classified as A. versicolor in the A. versicolor group, A. sulphureus in the A. ochraceus group, and A. niveus in the A. flavipes group.All of dose-survival curves obtained with the conidia of 10 strains showed the sigmoidal type having the D10 values between 18 and 30 krad. The survival curves obtained with the ascospores of A. glaucus group also showed the sigmoidal type having the D10 values of 54 krad. Radio-sensitivity of the dry conidia was similar to that of the dry ascospores, having D10 values between 50 to 58 krad.

Aspergilli as Ochratoxin Producers

To determine whether ochratoxin is produced by species of Aspergillus other than Asp. ochraceus, 44 strains representative of the 9 spp. composing the Asp. ochraceus group were grown on both pearled wheat and cracked corn in duplicate shaken flasks at 28°C for 5 days. Rice was a poor substrate for ochratoxin production. Moulded substrates were extracted with acetonitrile-water; partially purified extracts were assayed for ochratoxins by TLC. All positive samples were confirmed by solubility in sodium bicarbonate and preparation of methyl esters. Ochratoxins A and B were found in some strains of Asp. sulphureus, Asp. sclerotiorum, Asp. alliaceus, Asp. melleus, Asp. ochraceus, Asp. ostianus, and Asp. petrakii. No ochratoxin was produced by the one strain of Asp. elegans or any of 6 strains of Asp. auricomus. 5 of 9 strains of Asp. sclerotiorum and 5 of 11 strains of Asp. ochraceus were negative. All 7 strains of Asp. alliaceus were positive, but one was at a very low level. Generally, yields of ochratoxin were higher in wheat than in corn. Occasionally, as much ochratoxin B was produced as A. Highest yields of ochratoxins A and B were obtained from respective strains of Asp. ochraceus NRRL 3174 and NRRL 3519. Some strains of most species of the Asp. ochraceus group produce this mycotoxin as a secondary metabolite.

Aspergilli as Ochratoxin Producers

SUMMARYTo determine whether ochratoxin is produced by species of Aspergillus other than A. ochraceus, 44 strains representative of the nine species composing the A. ochraceus group were grown on both pearled wheat and cracked corn in duplicate shaken flasks at 28 C for 5 days. Rice was a poor substrate for production of ochratoxin. Molded substrates were extracted with acetonitrile-water; partially purified extracts were assayed for ochratoxins by thin-layer chromatography. All positive samples were confirmed by solubility in sodium bicarbonate and the preparation of methyl esters. Ochratoxins A and B were found in some strains of A. sulphureus, A. sclerotiorum, A. alliaceus, A. melleus, A. ochraceus, A. ostianus, and A. petrakii. No ochratoxin was produced by the one strain of A. elegans or any of six strains of A. auricomus. Five of nine strains of A. sclerotiorum and five of 11 strains of A. ochraceus were negative. All seven strains of A. alliaceus were positive, but one was at a very low level. Generally, yields of ochratoxin were higher in wheat than in corn. Occasionally, as much ochratoxin B was produced as A. Highest yields of ochratoxins A and B were obtained from respective strains of A. ochraceus NRRL 3174 and NRRL 3519. Some strains of most species of the A. ochraceus group produce this mycotoxin as a secondary metabolite.