Sambutoxin-Producing Isolates of Fusarium Species and Occurrence of Sambutoxin in Rotten Potato Tubers

A total of 50 Fusarium isolates representing 13 species from various sources were surveyed to determine their potential to produce sambutoxin. Sambutoxin production was restricted to Fusarium sambucinum and F. oxysporum, with the exception of one isolate of F. semitectum. Sambutoxin was produced by high percentages of F. sambucinum (80.0%) and F. oxysporum (84.6%) isolates at levels of 1.1 to 101.0 (mu)g/g. In addition, 9 (42.9%) of 21 rotten potato samples were contaminated with sambutoxin at levels of 15.8 to 78.1 ng/g.     

Moniliformin production and toxicity of different Fusarium species from Southern Africa.

Four new moniliformin-producing species of Fusarium were found, viz., F. acuminatum, F. concolor, F. equiseti, and F. semitectum. Isolates of F. acuminatum and F. concolor produced large amounts of moniliformin (3.4 and 9.5 g/kg, respectively), whereas isolates of the other three species yielded less than 30 mg/kg. The production of moniliformin by isolates of F. oxysporum and F. avenaceum from southern Africa is described. All 14 toxic isolates of F. oxysporum produced moniliformin. Most isolates of F. fusarioides and all six isolates of Fusarium moniliforme va. subglutinans tested produced moniliformin, as did 28 of 36 toxic isolates of F. moniliforme. A number of F. moniliforme isolates produced greater than 10 g/kg, and one isolate yielded 33.7 g/kg in corn after incubation for 5 weeks at 25 degrees C. Moniliformin production in the field in corn ears was shown by inoculating plants with known moniliformin-producing isolates of three Fusarium species. Yields of up to 645 mg/kg were recorded. Isolates of F. acuminatum, F. equiseti, F. fusarioides, and F. moniliforme were found that were highly toxic to ducklings but which did not produce moniliformin.     

Toxin production by Fusarium species from sugar beets and natural occurrence of zearalenone in beets and beet fibers.

Fifty-five Fusarium isolates belonging to nine species were collected from fungus-invaded tissue of stored sugar beets and identified as F. acuminatum (11 isolates), F. avenaceum (1 isolate), F. culmorum (1 isolate), F. equiseti (23 isolates), F. graminearum (4 isolates), F. oxysporum (1 isolate), F. solani (4 isolates), F. sporotrichioides (7 isolates), and F. subglutinans (2 isolates). All isolates were cultured on autoclaved rice grains and assayed for toxicity by feeding weanling female rats the ground-rice cultures of the isolates in a 50% mixture with a regular diet for 5 days. Fifty-eight percent of the isolates were acutely toxic to rats, 26% caused hematuria, 18% caused hemorrhages, and 29% caused uterine enlargement. In most cases, toxicity could not be accounted for by the known toxins found. The following mycotoxins were found in extracts of the rice cultures: zearalenone (22 to 6,282 micrograms/g), chlamydosporol (HM-8) (68 to 4,708 micrograms/g), moniliformin (45 to 400 micrograms/g), deoxynivalenol (10 to 34 micrograms/g), 15-acetyldeoxynivalenol (5 to 10 micrograms/g), diacetoxyscirpenol (22 to 63 micrograms/g), monoacetoxyscirpenol (21 to 26 micrograms/g), scirpenetriol (24 micrograms/g), T-2 toxin (4 to 425 micrograms/g), HT-2 toxin (2 to 284 micrograms/g), neosolaniol (2 to 250 micrograms/g), and T-2 tetraol (4 to 12 micrograms/g). F. equiseti was the predominant species found on visibly molded beets in the field. Six of 25 moldy sugar beet root samples collected in the field contained zearalenone in concentrations ranging between 12 and 391 ng/g, whereas 10 samples from commercial stockpiles were negative for zearalenone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Toxin production by Fusarium species from sugar beets and natural occurrence of zearalenone in beets and beet fibers.

Fifty-five Fusarium isolates belonging to nine species were collected from fungus-invaded tissue of stored sugar beets and identified as F. acuminatum (11 isolates), F. avenaceum (1 isolate), F. culmorum (1 isolate), F. equiseti (23 isolates), F. graminearum (4 isolates), F. oxysporum (1 isolate), F. solani (4 isolates), F. sporotrichioides (7 isolates), and F. subglutinans (2 isolates). All isolates were cultured on autoclaved rice grains and assayed for toxicity by feeding weanling female rats the ground-rice cultures of the isolates in a 50% mixture with a regular diet for 5 days. Fifty-eight percent of the isolates were acutely toxic to rats, 26% caused hematuria, 18% caused hemorrhages, and 29% caused uterine enlargement. In most cases, toxicity could not be accounted for by the known toxins found. The following mycotoxins were found in extracts of the rice cultures: zearalenone (22 to 6,282 micrograms/g), chlamydosporol (HM-8) (68 to 4,708 micrograms/g), moniliformin (45 to 400 micrograms/g), deoxynivalenol (10 to 34 micrograms/g), 15-acetyldeoxynivalenol (5 to 10 micrograms/g), diacetoxyscirpenol (22 to 63 micrograms/g), monoacetoxyscirpenol (21 to 26 micrograms/g), scirpenetriol (24 micrograms/g), T-2 toxin (4 to 425 micrograms/g), HT-2 toxin (2 to 284 micrograms/g), neosolaniol (2 to 250 micrograms/g), and T-2 tetraol (4 to 12 micrograms/g). F. equiseti was the predominant species found on visibly molded beets in the field. Six of 25 moldy sugar beet root samples collected in the field contained zearalenone in concentrations ranging between 12 and 391 ng/g, whereas 10 samples from commercial stockpiles were negative for zearalenone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mycotoxin Production by Fusarium Species Isolated from Bananas

The ability of Fusarium species isolated from bananas to produce mycotoxins was studied with 66 isolates of the following species: F. semitectum var. majus (8 isolates), F. camptoceras (3 isolates), a Fusarium sp. (3 isolates), F. moniliforme (16 isolates), F. proliferatum (9 isolates), F. subglutinans (3 isolates), F. solani (3 isolates), F. oxysporum (5 isolates), F. graminearum (7 isolates), F. dimerum (3 isolates), F. acuminatum (3 isolates), and F. equiseti (3 isolates). All isolates were cultured on autoclaved corn grains. Their toxicity to Artemia salina L. larvae was examined. Some of the toxic effects observed arose from the production of known mycotoxins that were determined by thin-layer chromatography, gas chromatography, or high-performance liquid chromatography. All F. camptoceras and Fusarium sp. isolates proved toxic to A. salina larvae; however, no specific toxic metabolites could be identified. This was also the case with eight isolates of F. moniliforme and three of F. proliferatum. The following mycotoxins were encountered in the corn culture extracts: fumonisin B(inf1) (40 to 2,900 (mu)g/g), fumonisin B(inf2) (150 to 320 (mu)g/g), moniliformin (10 to 1,670 (mu)g/g), zearalenone (5 to 470 (mu)g/g), (alpha)-zearalenol (5 to 10 (mu)g/g), deoxynivalenol (8 to 35 (mu)g/g), 3-acetyldeoxynivalenol (5 to 10 (mu)g/g), neosolaniol (50 to 180 (mu)g/g), and T-2 tetraol (5 to 15 (mu)g/g). Based on the results, additional compounds produced by the fungal isolates may play prominent roles in the toxic effects on larvae observed. This is the first reported study on the mycotoxin-producing abilities of Fusarium species that contaminate bananas.     

Mycological survey of Korean cereals and production of mycotoxins by Fusarium isolates.

The fungal species isolated from Korean cereals (barley, polished barley, wheat, rye, and malt) were Alternaria spp., Aspergillus spp., Chaetomium spp., Drechslera spp., Epicoccum sp., Fusarium spp., and Penicillium spp., etc. The number of Fusarium strains isolated was 36, and their ability to produce Fusarium mycotoxins on rice was tested. Nivalenol (NIV) was produced by Fusarium graminearum (7 of 9 isolates), Fusarium oxysporum (3 of 10 isolates), and Fusarium spp. (7 of 15 isolates). Of 15 isolates of Fusarium spp., 6 formed deoxynivalenol (DON). Fusarenon-X and 3-acetyl-DON were produced by most NIV- and DON-forming isolates, respectively. Zearalenone was produced by 3 isolates of F. graminearum, 1 isolate of Fusarium equiseti, and 11 isolates of Fusarium spp. T-2 toxin was not produced by any Fusarium isolates. The highest concentrations of mycotoxins produced by Fusarium isolates were 77.4 (NIV), 5.3 (DON), 138.3 (fusarenon-X), 40.6 (3-acetyl-DON), and 23.2 (zearalenone) micrograms/g.     

Mycological survey of Korean cereals and production of mycotoxins by Fusarium isolates

The fungal species isolated from Korean cereals (barley, polished barley, wheat, rye, and malt) were Alternaria spp., Aspergillus spp., Chaetomium spp., Drechslera spp., Epicoccum sp., Fusarium spp., and Penicillium spp., etc. The number of Fusarium strains isolated was 36, and their ability to produce Fusarium mycotoxins on rice was tested. Nivalenol (NIV) was produced by Fusarium graminearum (7 of 9 isolates), Fusarium oxysporum (3 of 10 isolates), and Fusarium spp. (7 of 15 isolates). Of 15 isolates of Fusarium spp., 6 formed deoxynivalenol (DON). Fusarenon-X and 3-acetyl-DON were produced by most NIV- and DON-forming isolates, respectively. Zearalenone was produced by 3 isolates of F. graminearum, 1 isolate of Fusarium equiseti, and 11 isolates of Fusarium spp. T-2 toxin was not produced by any Fusarium isolates. The highest concentrations of mycotoxins produced by Fusarium isolates were 77.4 (NIV), 5.3 (DON), 138.3 (fusarenon-X), 40.6 (3-acetyl-DON), and 23.2 (zearalenone) micrograms/g.     

Toxigenicity of some fusaria associated with plant and human diseases in the Malaysian peninsula

In the course of a plant disease survey of the Malaysian Peninsula (Malaysia comprises the Malaysian Peninsula, Sabah and Sarawak) during the period 1981-1986, more than 1000 isolates of Fusarium were obtained from diseased plants and seeds. Two further isolates were obtained from patients admitted to hospitals in the same area. The occurrences of F. proliferatum, F. nygamai and F. longipes are new records for the Malaysian Peninsula and the association of F. solani and F. oxysporum var. redolens with human diseases does not seem to have been reported previously. Ten representative species which could be classified into seven sections of the genus were selected for studies of their toxigenicity in liquid cultures and/or on rice. Crude toxin preparations from culture filtrates or extracts of the inoculated rice were tested for toxicity to brine shrimp larvae and tobacco mesophyll protoplasts. The protoplasts were more sensitive than the brine shrimp larvae to the toxin preparations, except those from the isolates of F. solani and F. oxysporum var. redolens obtained from either humans or tobacco. The toxicity of the preparations from rice cultures per g rice was always greater than the toxicity per ml of culture filtrates from cultures grown on Czapek-Dox broth, Czapek-Dox supplemented with 1% (w/v) peptone or Czapek-Dox supplemented with 5% (w/v) tobacco extract. The activity of all toxin preparations was stable to heat. It is concluded that the occurrence of toxigenic species of Fusarium in the Malaysian Peninsula is widespread and that they may pose a serious threat to the health of human, animal and plant populations.     

Absence of trichothecenes in toxigenic isolates of Fusarium moniliforme

Thirty-four isolates of Fusarium moniliforme were obtained from cereal grains collected in various parts of the world. The isolates were grown on rice and tested as a diet for toxicity to rats. Of these isolates, 53% caused death, 12% caused congestion and hemorrhage of the stomach and intestine as well as hematuria, 21% caused diarrhea, 38% caused weight loss, and 9% were nontoxic. The cultures were tested to T-2, HT-2, neosolaniol, acetyl-T-2, T-2-tetraol, iso-T-2, diacetoxyscirpenol, monoacetoxyscirpenol, deoxynivalenol, nivalenol, fusarenone-X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, zearalenone, moniliformin, fusarochromanone, fusarin-C, and wortmannin; all were negative. In addition, F. moniliforme NRRL A25820 was grown on corn and banana fruit as solid substrates as well as on a defined liquid medium; none of the above toxins were found. When F. moniliforme NRRL A25820 was incorporated into a rat diet, no toxicity was noted. Twenty-eight additional isolates of F. moniliforme, isolated from feed associated with equine leukoencephalomalacia, were grown on cracked corn for 2 weeks. The cultures were negative when tested for deoxynivalenol, 15-acetyldeoxynivalenol, diacetoxyscirpenol, monoacetoxyscirpenol, nivalenol, and fusarenone X. Seventy-five percent of the isolates were toxic to ducklings, indicating the presence of a toxin other than trichothecenes. Our results support the conclusion that F. moniliforme does not produce trichothecenes.     

A Hemorrhagic Factor (Apicidin) Produced by Toxic Fusarium Isolates from Soybean Seeds

Fifty-two isolates of Fusarium species were obtained from soybean seeds from various parts of Korea and identified as Fusarium oxysporum, F. moniliforme, F. semitectum, F. solani, F. graminearum, or F. lateritium. These isolates were grown on autoclaved wheat grains and examined for toxicity in a rat-feeding test. Nine cultures were toxic to rats. One of these, a culture of Fusarium sp. strain KCTC 16677, produced apicidin, an antiprotozoal agent that caused toxic effects in rats (including body weight loss; hemorrhage in the stomach, intestines, and bladder; and finally death) when rats were fed diets supplemented with 0.05 and 0.1% apicidin. The toxin was toxic to brine shrimp (the 50% lethal concentration was 40 μg/ml) and was weakly cytotoxic to human and mouse tumor cell lines.     

Production of Trichothecene Mycotoxins by Fusarium Species in Shake Culture

Twelve T-2 toxin-producing isolates and four fusarenon-X-producing isolates of Fusarium species were examined for their ability to produce trichothecene mycotoxins in shake culture and jar fermentation. T-2 toxin producers such as Fusarium solani, F. sporotrichiodes, and F. tricinctum produced T-2 toxin and neosolaniol in semisynthetic medium. F. solani M-1-1 produced the largest amount of the mycotoxins in a nutrient medium consisting of 5% glucose (or sucrose), 0.1% peptone, and 0.1% yeast extract in either shake culture or jar fermentation at 24 to 27 C for 5 days. None of the isolates produced significant amount of fusarenon-X in shake cultures.     

Isolation and purification of a hemorrhagic factor (wortmannin) from Fusarium oxysporum (N17B).

An isolate of Fusarium oxysporum Schlecht, emend. Synd. et Hans. N17B isolated from a grassy area in Lakselv, Norway (Arctic region) produced a toxin in culture when grown on rice in the laboratory. This new toxin, which was given the trivial name of H-1 (indicating hemorrhagic factor), caused toxic effects in rats, including food refusal, weight loss, hemorrhage in the stomach, intestines, heart, and thymus, and finally death. The UV spectrum of H-1 showed 210, 254, and 292 nm as absorption maxima. The infrared spectrum showed carbonyl groups at 1,675 and 1,750 cm-1 and an ether group at 1,215 cm-1. H-1 does not fluoresce under short- or long-wavelength UV light and exists as fluffy, white crystals that turn yellow when subjected to basic reagents such as ammonium hydroxide or tetraethylenepentamine. Elemental and accurate mass determinations in both electron impact and positive chemical ionization indicate an empirical formula of C23H24O8. Its mass spectra (electron impact, chemical ionization, and fast atom bombardment [FAB]) show a molecular ion of 428 and major fragments at m/z+ 386, 368, 355, and 295. H-1 was found to be identical to the antibiotic called wortmannin which is produced by Penicillium wortmannii and Myrothecium roridum. This is the first report of the synthesis of wortmannin by species of the genus Fusarium.     

Isolation and purification of a hemorrhagic factor (wortmannin) from Fusarium oxysporum (N17B)

An isolate of Fusarium oxysporum Schlecht, emend. Synd. et Hans. N17B isolated from a grassy area in Lakselv, Norway (Arctic region) produced a toxin in culture when grown on rice in the laboratory. This new toxin, which was given the trivial name of H-1 (indicating hemorrhagic factor), caused toxic effects in rats, including food refusal, weight loss, hemorrhage in the stomach, intestines, heart, and thymus, and finally death. The UV spectrum of H-1 showed 210, 254, and 292 nm as absorption maxima. The infrared spectrum showed carbonyl groups at 1,675 and 1,750 cm-1 and an ether group at 1,215 cm-1. H-1 does not fluoresce under short- or long-wavelength UV light and exists as fluffy, white crystals that turn yellow when subjected to basic reagents such as ammonium hydroxide or tetraethylenepentamine. Elemental and accurate mass determinations in both electron impact and positive chemical ionization indicate an empirical formula of C23H24O8. Its mass spectra (electron impact, chemical ionization, and fast atom bombardment [FAB]) show a molecular ion of 428 and major fragments at m/z+ 386, 368, 355, and 295. H-1 was found to be identical to the antibiotic called wortmannin which is produced by Penicillium wortmannii and Myrothecium roridum. This is the first report of the synthesis of wortmannin by species of the genus Fusarium.     

Fusarium rot in cucumber greenhouses of Jiroft region

The present work was done to identify Fusarium species that cause Fusarium rot in greenhouse cucumber crop in Jiroft region (Kerman, Iran), in 2006–2007. During these years, a vast sampling was done from several greenhouses of Jiroft. The plants with rot symptoms as well as the soil samples of greenhouse were transferred to lab. The isolates of plants and soil samples were detached by direct isolation of the infected tissue and soil suspension methods, respectively. Totally 120 isolates were obtained, which were classified into the following six species according to their morphological and physiological characteristics: Fusarium oxysporum, Fusarium solani, Fusarium culmorum, Fusarium monoliforme, Fusarium sambucinum, Fusarium subglutinans. It is the first time that three of these taxons, i.e. F. culmorum, F. monoliforme and F. subglutinan are reported in cucumber of Iran. Pathogenesis studies of the isolates were done by mycelium placement and spore suspension injection methods in sterile soil under greenhouse conditions. Then the disease symptoms were investigated.     

Effect of dsRNA-containing and dsRNA-free hypovirulent isolates of Fusarium oxysporum on severity of Fusarium seedling disease of soybean in naturally infested soil

In the sandy soils of eastern Virginia, soybean seedlings are colonized by hypovirulent and virulent isolates of Fusarium oxysporum and F. solani. Our objectives were to determine if prior inoculation of soybean seeds with hypovirulent F. oxysporum isolates reduced severity of seedling disease in naturally infested soil, and to determine if there was an association between the presence of dsRNA mycovirus and hypovirulence in isolates of F. oxysporum and F. solani from soybean plants. The presence of dsRNA was not associated with hypovirulence in F. oxysporum since some hypovirulent isolates contained dsRNA while other hypovirulent isolates did not. Furthermore, of six dsRNA-containing F. oxysporum isolates, three were hypovirulent and three were virulent. Four segments of dsRNA, with sizes of 4.0, 3.1, 2.7 and 2.2 kb were detected in extracts of all six F. oxysporum isolates. No hypovirulent or dsRNA-containing of F. solani isolates were found. Prior inoculation of cv. Essex soybean seeds with conidia of dsRNA-free hypovirulent F. oxysporum isolates significantly (P < 0.05) reduced disease severity on cotyledons and hypocotyls, and increased the rate of seedling emergence in field soil, compared to control plants. No significant (P > 0.05) differences were found between dsRNA-containing and dsRNA-free hypovirulent F. oxysporum isolates in their effects on reducing disease severity. Hypovirulent isolates that colonize soybean tissues may play a role in reducing Fusarium seedling disease of soybean in natural soils.     

Mycotoxin production by Fusarium oxysporum and Fusarium sporotrichioides isolated from Baccharis spp. from Brazil

Fusarium oxysporum isolated from roots of and soil around Baccharis species from Brazil produced the trichothecenes T-2 toxin, HT-2 toxin, diacetoxyscirpenol, and 3'-OH T-2 (TC-1), whereas Fusarium sporotrichioides from the same source produced T-2 toxin, HT-2 toxin, acetyl T-2, neosolaniol, TC-1, 3'-OH HT-2 (TC-3), iso-T-2, T-2 triol, T-2 tetraol, and the nontrichothecenes moniliformin and fusarin C. Several unknown toxins were found but not identified. Not found were macrocyclic trichothecenes, zearalenone, wortmannin, and fusarochromanone (TDP-1).     

Mycotoxin production by Fusarium oxysporum and Fusarium sporotrichioides isolated from Baccharis spp. from Brazil.

Fusarium oxysporum isolated from roots of and soil around Baccharis species from Brazil produced the trichothecenes T-2 toxin, HT-2 toxin, diacetoxyscirpenol, and 3'-OH T-2 (TC-1), whereas Fusarium sporotrichioides from the same source produced T-2 toxin, HT-2 toxin, acetyl T-2, neosolaniol, TC-1, 3'-OH HT-2 (TC-3), iso-T-2, T-2 triol, T-2 tetraol, and the nontrichothecenes moniliformin and fusarin C. Several unknown toxins were found but not identified. Not found were macrocyclic trichothecenes, zearalenone, wortmannin, and fusarochromanone (TDP-1).     

Isoverrucarol production by Fusarium oxysporum CJS-12 isolated from corn

Isoverrucarol (3,15-dihydroxy-12,13-epoxy-trichothec-9-ene) was isolated and purified from wheat cultures of a toxic strain of Fusarium oxysporum CJS-12. The toxin was characterized by thin-layer chromatography, gas chromatography-mass spectrometry, and 1H and 13C nuclear magnetic resonance spectrometry. Isoverrucarol caused toxic effects in rats, including loss of appetite, bodily weakness, severe mucosae of the stomach, and death, when administered orally at 10 and 20 mg/kg of body weight. The toxin also caused a definite dermatitic reaction of epidermis and an edematic-necrotic response of the dermis.     

Isoverrucarol production by Fusarium oxysporum CJS-12 isolated from corn.

Isoverrucarol (3,15-dihydroxy-12,13-epoxy-trichothec-9-ene) was isolated and purified from wheat cultures of a toxic strain of Fusarium oxysporum CJS-12. The toxin was characterized by thin-layer chromatography, gas chromatography-mass spectrometry, and 1H and 13C nuclear magnetic resonance spectrometry. Isoverrucarol caused toxic effects in rats, including loss of appetite, bodily weakness, severe mucosae of the stomach, and death, when administered orally at 10 and 20 mg/kg of body weight. The toxin also caused a definite dermatitic reaction of epidermis and an edematic-necrotic response of the dermis.     

Production of zearalenone,nivalenol, moniliformin,and wortmannin from toxigenic cultures ofFusarium obtained from pasture soil samples collected in New Zealand

One culture ofF avenaceum, 4 cultures ofF oxysporum, and 11 cultures of Fsambucinum were isolated from soil samples of pasture in New Zealand in 1987. All cultures, when grown on rice media and fed to rats caused a weight loss in rats as well as toxic signs including hemorrhaging and congestion, uterine enlargement, and hematuria. 6 out of 16 cultures caused death in rat feeding tests.F oxysporum #1 killed rats (feeding test) within 5-12hrs. 10 cultures produced zearalenone (19 to 8,849 ppm), 8 cultures produced nivalenol (32 to 117 ppm), 1 culture,F sambucinum #8, produced wortmannin (40 ppm), and 5 cultures produced moniliformin (19 to 9,000ppm). We report for the first time the co-occurrence of zearalenone, nivalenol, and moniliformin produced byF sambucinum #3 in culture.F avenaceum #1 andF oxysporum cultures (nos 1, 2, and 3) produced moniliformin alone.F oxysporum #4 produced zearalenone alone as well.F sambucinum #5 caused erythema in the small intestine of rats and 100% mortality and did not produce any known toxin(s). Nivalenol when administered to the stomach of rats orally at levels 10, 20, and 40mg/kg body weight caused inflammation in the intestines, coma, and death. The mycotoxins T-2 toxin, HT-2 toxin, T-2 tetraol, diacetoxyscirpenol (DAS), monoacetoxyscirpenol (MAS), deoxynivalenol (DON), 3-acetyl-and 15-acetyldeoxynivalenol, depoxynivalenol, fusarenon-X, alpha-and beta-zearalenone, and fusarochromanone (TDP-1) were not detected in the extracts of these cultures.