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J C Frisvad

Publications and source records attributed to J C Frisvad.

At least 37 records · Page 2Linked to original sources

Moulds in food spoilage.

There is an increasing knowledge and understanding of the role played by moulds in food spoilage. Especially the discovery of mycotoxin production in foods has highlighted the importance of moulds in food quality. It is, however, only within the last 5-10 years that major progresses have been made towards the prevention of spoilage caused by moulds. This is due to recent international agreements on taxonomy and analytical methods for foodborne moulds, which has led to the discovery, that a specific, very limited funga (= mycobiota) is responsible for the spoilage of each kind of food. This is called the associated or critical funga and has been shown to consist of less than ten species. In this paper the associated funga is described for the following foods: citrus and pomaceous fruit, potato and yam tubers, onions, rye, wheat, rye bread, cheese and fermented sausage and whenever possible the selective principle of the food is discussed. In the description only references which are using the new taxonomy and mycological methods have been used. The individual fungas are very different from each other, which again means that the potential appearance of a specific mycotoxin is restricted to a limited number of foods. The important mycotoxin pattern of each food is described including toxins which originate from 'carry over'. For some foods examples are also given on spoilage of sensoric properties due to moulds. Finally, preventive action against the growth of the associated funga is described for some of the foods and it is concluded that optimization of the prevention and control of moulds in foods must be based on knowledge of the associated funga.

Cheese↗

2D-PAGE examination of mRNA populations from Penicillium freii mutants deficient in xanthomegnin biosynthesis.

Penicillium freii (Lund and Frisvad 1994) mutants deficient in the synthesis of xanthomegnin were isolated. In vitro translated mRNA populations from selected radiation induced mutants and naturally occurring P. freii strains not able to produce xanthomegnin were examined by 2-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Specific translation products were absent in mutants and natural isolates unable to produce xanthomegnin metabolites. One mutant (TSM 73) did not produce several of these translation products, indicating that a mutation in a regulatory gene involved in xanthomegnin production had occurred.

Electrophoresis, Gel, Two-Dimensional↗

Associated mycoflora of rye bread.

Penicillium roqueforti (27%), P. corylophilum (20%) and Eurotium species (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 variotti (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 total mycoflora of rye bread. Identification of the fungi in the production environment in a rye bread factory showed the locality of potential contamination sources. Elimination of the contamination sources by improved cleaning and disinfection procedures quickly resulted in a significant reduction in the frequency of mould growth in the packaged rye bread.

Aspergillus flavus↗

Nephrotoxigenic Penicillium species occurring on farm-stored cereal grains in western Canada.

The incidence of nephrotoxigenic Penicillium species on farm-stored cereals in western Canada was determined by morphological and metabolite profile examination. Of the 142 isolates examined 102 were toxin producers with 61 P. aurantiogriseum and 27 P. freii. Other nephrotoxigenic species included P. tricolor (6 isolates), P. verrucosum Chemotype II (4 isolates) and P. viridicatum Westling (4 isolates). The nephrotoxigenic Penicillium species profile for western Canada appears to differ from that of Denmark where P. verrucosum, P. cyclopium, P. freii and, to a lesser extent, P. aurantiogriseum, P. polonicum, and P. viridicatum predominate.

Agriculture↗

Penicillin production by Penicillium nalgiovense.

A large number of Penicillium nalgiovense strains were found to be as good penicillin producers on optimal production media as strains of Penicillium chrysogenum. It is not known whether penicillin can be produced on fermented sausages, but selection for non-penicillin producing fermenting strains of P. nalgiovense is suggested.

Culture Media↗

Antifungal macrocyclic polylactones from Penicillium verruculosum.

Three macrocyclic polylactones have been isolated from Penicillium verruculosum. Two were found to be novel and the third to be identical with NG-012(1). Their structures were elucidated by spectroscopic and chemical methods. A full assignment of 1H- and 13C-resonances in acetone-d6 are given for all three compounds. The compounds show antifungal activity.

Animals↗

Chemotaxonomy of the genus Talaromyces.

Species of the ascomycetous genus Talaromyces have been examined for profiles of secondary metabolites on TLC. The greatest number of specific metabolites were produced on oatmeal-, malt extract- and yeast-extract sucrose agars. Profiles of intracellular secondary metabolites produced on oatmeal agar were specific for each species and provided a means of simple differentiation of the taxa. Examination of the most important species using high performence liquid chromatography (HPLC) allowed to solve some taxonomic problems. Known mycotoxins are produced by T. stipitatus (duclauxin, talaromycins, botryodiploidin), T. stipitatus chemotype II (emodin), T. panasenkoi (spiculisporic acid), T. trachyspermus (spiculisporic acid), T. macrosporus (duclauxin) and T. wortmannii (rugulosin). Wortmannin is produced by an atypical strain of T. flavus but not T. wortmannii. Several other secondary metabolites were discovered for the first time in the following species: Glauconic acid is produced by T. panasenkoi, T. ohiensis and T. trachyspermus; vermiculine by T. ohiensis; duclauxin by T. flavus var. macrosporus and the mitorubrins by T. flavus and T. udagawae. The profiles of secondary metabolites support the established taxonomy of the species based on morphology, showing the genetic stability of profiles of secondary metabolites in Talaromyces. Two new taxa are proposed: T. macrosporus comb. nov. (stat. anam. Penicillium macrosporum stat. nov.), and Penicillium vonarxii, sp. nov. for the anamorph of T. luteus.

Ascomycota↗

Growth of and fumitremorgin production by Neosartorya fischeri as affected by temperature, light, and water activity.

The effects of temperature, light, and water activity (aw) on the growth and fumitremorgin production of a heat-resistant mold, Neosartorya fischeri, cultured on Czapek Yeast Autolysate agar (CYA) were studied for incubation periods of up to 74 days. Colonies were examined visually, and extracts of mycelia and CYA on which the mold was cultured were analyzed for mycotoxin content by high-performance liquid chromatography. Growth always resulted in the production of the tremorgenic mycotoxins verruculogen and fumitremorgins A and C. The optimum temperatures for the production of verruculogen and fumitremorgins A and C on CYA at pH 7.0 were 25, 30, and 37 degrees C, respectively. The production of fumitremorgin C by N. fischeri has not been previously reported. Fumitremorgin production was retarded at 15 degrees C, but an extension of the incubation period resulted in concentrations approaching those observed at 25 degrees C. Light clearly enhanced fumitremorgin production on CYA (pH 7.0, 25 degrees C), but not as dramatically as did the addition of glucose, fructose, or sucrose to CYA growth medium (pH 3.5, 25 degrees C). Growth and fumitremorgin production was greatest at aw of 0.980 on CYA supplemented with glucose or fructose and at aw of 0.990 on CYA supplemented with sucrose. Growth and fumitremorgin production were observed at aw as low as 0.925 on glucose-supplemented CYA but not at aw lower than 0.970 on CYA supplemented with sucrose. Verruculogen was produced in the highest amount on all test media, followed by fumitremorgin A and fumitremorgin C.

Ascomycota↗

Standardized high-performance liquid chromatography of 182 mycotoxins and other fungal metabolites based on alkylphenone retention indices and UV-VIS spectra (diode array detection).

A general standardized method for the analysis of mycotoxins and other fungal secondary metabolites has been developed, based on high-performance liquid chromatography (HPLC) with an alkylphenone retention index and photodiode-array detection combined with thin-layer chromatography (TLC) in two different eluents. Each fungal secondary metabolite is characterized by its bracketed alkylphenone retention time index, its UV-VIS absorption maxima and its retardation factors relative to griseofulvin in two TLC eluents. This system is effective for the comparison of chemotaxonomic data in different laboratories and for a precise identification of fungi based on organic solvent extracts of fungal cultures. All important groups of mycotoxins and other fungal secondary metabolites could be detected in the HPLC system described and data are listed for 182 metabolites. The fungal secondary metabolites separated and characterized include aflatoxin B1, B2, G1 and G2, ochratoxin A, citrinin, penicillin acid, viomellein, penitrem A, patulin, sterigmatocystin, alternariol, tenuazonic acid, trichothecenes, roquefortines, fusarin C, zearalenone, PR-toxin, citreoviridin, viridicatumtoxin, verruculogen, rugulosin, cyclopiazonic acid, penicillin G and many other alkaloids, polyketides and terpenes.

Aspergillus↗

High-performance liquid chromatographic determination of profiles of mycotoxins and other secondary metabolites.

A reversed-phase high-performance liquid chromatographic determination of profiles of mycotoxins and other fungal secondary metabolites has been developed. Penicillium, Aspergillus and Fusarium polyketides, terpenes and alkaloids have been emphasized. In a gradient elution, using water-acetonitrile containing 0.05% trifluoroacetic acid, 134 secondary metabolites were eluted evenly with retention times from 1.08 to 34.48 min. Metabolites with the same retention time were usually not produced by the same species. As UV detection at 254 nm was used, some mycotoxins (type A trichothecenes, viridicatumtoxin, peptide-like compounds and xanthomegnin) could not be detected. The method appears to be valuable for chemotaxonomic studies of fungi. Unpurified concentrated chloroform-methanol extracts of petri dish cultures analysed by the proposed method presented gave species-specific characteristic profiles of known and unknown secondary metabolites and mycotoxins.

Biotransformation↗

Antigenic characterization of Penicillium camemberti and related common cheese contaminants.

Twenty-four isolates of Penicillium (including a green-spored mutant from a French Brie cheese, Penicillium camemberti) with a proposed relationship to the white cheese mold P. camemberti were investigated by immunological procedures. These penicillia, which are representative of species that have caused considerable taxonomic confusion, had common micromorphology (terverticillate penicilli with rough and smooth stipes and smooth ellipsoidal to subglobose [(3 to 5) X 2 1/2 to 4 1/2 microns] conidia); growth rates; good growth on creatine sucrose agar, cheese, and other products with a high amount of protein and lipid as a primary habitat; production (with the exception of Penicillium solitum) of cyclopiazonic acid; and the ability to grow at low temperatures and water activities. The isolates that were investigated proved to be strictly antigenically related. Absorbed antiserum of the green-spored mutant of P. camemberti showed a specific precipitin band when tested by immunodiffusion either with its homologous reference antigen or with the exoantigens obtained from different isolates. The precipitin band was not present in any P. camemberti starter culture but in many unwanted cheese contaminants. The precipitin band can be used in the purity control of P. camemberti starter culture spore preparations. Analysis of the exoantigens of all the cultures by reversed phase high-performance liquid chromatography allowed us to subdivide these penicillia into nine groups below the species level. The results indicate that P. commune Thom is the wild-type ancestor of P. camemberti.

Antigens, Bacterial↗

A selective and indicative medium for groups of Penicillium viridicatum producing different mycotoxins in cereals.

A medium, pentachloronitrobenzene-rose bengal-yeast extract-sucrose agar (PRYES), for the isolation of moulds occurring during storage of cereals has been developed and compared with other selective media. The basal medium is yeast extract agar containing 15% sucrose (w/v). In addition to the sucrose content further selective measures include the addition of antibacterial antibiotics chloramphenicol and chlortetracycline (50 mg/l), the fungicides rose bengal (25 mg/l each), and pentachloronitrobenzene (1 g/l) and a low incubation temperature (20 degrees C). Members of the Mucorales were completely inhibited, and fast-growing species of other moulds were slightly inhibited, allowing important storage moulds to develop. The important ochratoxin A and citrinin-producing Penicillium viridicatum group II was indicated by a typical violet brown reverse on PRYES. Producers of xanthomegnin and viomellein (P. viridicatum group I and P. aurantiogriseum) were indicated on PRYES by their yellow reverse and obverse colours. The medium was used for screening 40 samples of barley, and moulds with the characteristic colours were all identified as the species mentioned above.

Citrinin↗

Simple screening method for molds producing intracellular mycotoxins in pure cultures.

A simple screening method for molds producing the intracellular mycotoxins brevianamide A, citreoviridin, cyclopiazonic acid, luteoskyrin, penitrem A, roquefortine C, sterigmatocystin, verruculogen, viomellein, and xanthomegnin was developed. After removing an agar plug from the mold culture, the mycelium on the plug is wetted with a drop of methanol-chloroform (1:2). By this treatment the intracellular mycotoxins are extracted within seconds and transferred directly to a thin-layer chromatography plate by immediately placing the plug on the plate while the mycelium is still wet. After removal of the plug, known thin-layer chromatographic procedures are carried out. The substrate (Czapek yeast autolysate agar) and growth conditions (25 degrees C for 7 days) used by Penicillium taxonomists proved suitable for the production of the mycotoxins investigated when 60 known toxigenic isolates and 865 cultures isolated from foods and feedstuffs were tested with this screening method.

Aspergillus↗

Classification of terverticillate penicillia based on profiles of mycotoxins and other secondary metabolites.

Strains of available terverticillate penicillium species and varieties were analyzed for profiles of known mycotoxins and other secondary metabolites produced on Czapek yeast autolysate agar (intracellular metabolites) and yeast extract-sucrose agar (extracellular metabolites) by using simple thin-layer chromatography screening techniques. These strains (2,473 in all) could be classified into 29 groups based on profiles of secondary metabolites. Most of these profiles of secondary metabolites were distinct, containing several biosynthetically different mycotoxins and unknown metabolites characterized by distinct colors and retardation factors on thin-layer chromatography plates. Some species (P. italicum and P. atramentosum) only produced one or two metabolites by the simple screening methods. The 29 groups based on profiles of secondary metabolites were known species or subgroups thereof. These species and subgroups were independently identifiable by using morphological and physiological criteria. The species accepted, the number of isolates in each species investigated, and the mycotoxins they produced were: P. atramentosum, 4; P. aurantiogriseum, 510 (group I: penicillic acid and S-toxin and group II: penicillic acid, penitrem A [low frequency], terrestric acid [low frequency], viomellein, and xanthomegnin); P. brevicompactum, 81 (brevianamid A and mycophenolic acid); P. camembertii group I, 38, and group II, 114 (cyclopiazonic acid); P. chrysogenum, 87 (penicillin, roquefortine C, and PR-toxin); P. claviforme, 4 (patulin and roquefortine C); P. clavigerum, 4 (penitrem A); P. concentricum group I, 10 (griseofulvin and roquefortine C), and group II, 3 (patulin and roquefortine C); P. crustosum, 123 (penitrem A, roquefortine C, and terrestric acid); P. echinulatum, 13; P. expansum, 91 (citrinin, patulin, and roquefortine C); P. granulatum, 6 (patulin, penitrem A, and roquefortine C [traces]); P. griseofulvum, 21 (cyclopiazonic acid, griseofulvin, patulin, and roquefortine C); P. hirsutum, 100 (group I: terrestric acid; group II: citrinin, penicillic acid , roquefortine C, and terrestric acid; and group III: roquefortine C and terrestric acid), P. hirsutum group IV, 2 (chaetoglobosin C); P. isariiforme, 1; P. italicum, 41; P. mali, 104; P. roquefortii, 78 (group I: mycophenolic acid, PR-toxin, and roquefortine C and group II: mycophenolic acid, patulin, penicillic acid [low frequency], and roquefortine C); P. viridicatum group I, 634 (brevianamid A [low frequency], penicillic acid, viomellein, and xanthomegnin), P. viridicatum group II and III, 494 (citrinin and ochratoxin A), P. viridicatum group IV, 12 (griseofulvin and viridicatumtoxin). It is proposed that profiles of secondary metabolites be strongly emphasized in any future revision of the penicillia.

Mycotoxins↗

Physiological criteria and mycotoxin production as AIDS in identification of common asymmetric penicillia.

The taxonomy of the asymmetric (predominantly terverticillate) penicillia is based on morphological differences that leave identification difficult. The application of physiological criteria facilitated the identification of the common asymmetric penicillia investigated. Changes in the placement of some strains of these penicillia made the connection to mycotoxin-producing ability clearer. The classical criterion of conidium color was deemphasized and replaced by the following criteria: (i) growth on nitrite-sucrose agar and (ii) growth and acid (and subsequent base) production on creatine-sucrose agar (containing bromocresol purple). Other criteria used or developed were: (iii) growth on sorbic acid plus benzoic acid agar (50 + 50 ppm, pH 3.8), (iv) growth on an agar containing 1,000 ppm propionic acid (pH 3.8), (v) growth on an agar containing 0.5% acetic acid, (vi) growth at 37 degrees C, (vii) growth rate on an agar containing 0.1% pentachloronitrobenzene, (viii) production of extracellular tricaproinase, and (ix) fasciculation on a medium containing 10 ppm botran (2,6-dichloro-4-nitroanilin). The pattern of extracellular metabolites after thin-layer chromatography was used as a chemotaxonomic criterion. The species investigated, the number of isolates investigated, and the toxins which some of these isolates produce were: Penicillium roqueforti (18) (patulin), P. citrinum (11) (citrinin), P. patulum (9) (patulin and griseofulvin), P. expansum (patulin and citrinin), P. hirsutum (13), P. brevicompactum (19), and P. chrysogenum (12). Widespread species of the P. cyclopium, P. viridicatum, and P. expansum series of Raper and Thom (A Manual of the Penicillia, 1949) were subdivided into four new groups: "P. crustosum pA" (29) (penitrem A), "P. melanochlorum" (29), "P. cyclopium p" (119) (penicillic acid and infrequently penitrem A), and "P. viridicatum o-c" (43) (ochratoxin A and citrinin). "P. viridicatum o-c" was separated from "P. cyclopium p" due to its ability to grow on nitrite as sole nitrogen source. The species and groups investigated were related to the new taxonomic classification of the genus Penicillium according to Pitt.

Journal Article↗

Analysis and screening for mycotoxins and other secondary metabolites in fungal cultures by thin-layer chromatography and high-performance liquid chromatography.

Methods for the screening of fungal cultures for toxic secondary metabolites are reviewed. Thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are good general analytical methods for secondary metabolites in unpurified extracts. The combination of normal phase TLC using different chemical spray reagents with reversed phase HPLC, using alkylphenone retention indices and diode array detection, is a powerful technique for identifying the individual mycotoxins detected. The results of the screening methods are very dependent of the growth media and incubation conditions and a general method for the detection of Penicillium, Aspergillus, Fusarium, Alternaria and Cladosporium toxins is suggested.

Chromatography, High Pressure Liquid↗

The connection between the Penicillia and Aspergilli and mycotoxins with special emphasis on misidentified isolates.

Species of Penicillium and Aspergillus are the most potent mycotoxin producers, but the connection between species and profiles of mycotoxins has been obscured by many misidentifications of fungal isolates, especially in Penicillium. Available producers of known mycotoxins in the two important genera were examined concerning identity and production of secondary metabolites using thin-layer chromatography and high performance liquid chromatography with diode array detection. 152 isolates of Penicillium were reclassified, leaving the connection between species and mycotoxin profiles much clearer in this genus. Earlier data on mycotoxin production by different taxa were confirmed by analyzing several isolates of each taxon.

Aspergillus↗

Antibacterial activity of marine-derived fungi.

A total of 227 marine isolates of ubiquitous fungi were cultivated on different media and the secondary metabolite content of the extracts (ethyl acetate/chloroform/methanol 3:2:1) characterized by HPLC. The fungi were secured from animals, plants and sediments of Venezuelan waters (0-10 m) including mangroves and lagoonal areas. The extracts were tested for antibacterial activity. A total of 7 were active towards Vibrio parahaemolyticus and 55 towards Staphylococcus aureus, representing 18 different fungal species from 8 ascomycetous genera. For 61 strains of Penicillium citrinum antibacterial activity correlated well with content of secondary metabolites as measured by HPLC. Thirteen isolates of Penicillium steckii produced very similar profiles of secondary metabolites and 6 of these had activity against either V. parahaemolyticus or S. aureus or both.

Anti-Bacterial Agents↗