Trichothecene mycotoxins produced byFusarium sporotrichioides strain P-11

A non-linear model for temperature-dependent sporulation and T-2 and HT-2 production of Fusarium langsethiae and Fusarium sporotrichioides

This research has produced new quantitative data on the sporulation and T-2+HT-2 toxin production that could be further integrated to develop a comprehensive disease or toxin prediction model for Fusarium langsethiae and Fusarium sporotrichioides. Experiments were conducted to determine the effect of temperature or incubation time on sporulation and the effect of temperature on T-2+HT-2 toxin production of strains of the two species. F. sporotrichioides demonstrated a preference for higher temperatures than F. langsethiae during sporulation; the optimum temperature was 24.5 ± 0.7 °C for F. langsethiae and 32.3 ± 2.1 °C for F. sporotrichioides, according to the Beta equation fitted to the data. The dynamics of sporulation over different incubation times were fitted by a Gompertz function. The maximum spore production was estimated to be after 18 and 8 d incubation at optimum temperatures for F. langsethiae and F. sporotrichioides, respectively. F. sporotrichioides produced more T-2+HT-2 than F. langsethiae. The best fit of the effect of temperature on T-2+HT-2 production in wheat grains was obtained with a Beta equation showing an optimum temperature of 14.7 ± 0.8 °C for F. langsethiae and 12.1 ± 0.2 °C for F. sporotrichioides. The optimum temperature for mycotoxin production was lower than for sporulation.

Analysis of T-2 and HT-2 toxins in cereal grains by immunoaffinity clean-up and liquid chromatography with fluorescence detection

A sensitive, precise and accurate method has been developed for the simultaneous determination of T-2 and HT-2 toxins in cereal grains at ppb levels using high-performance liquid chromatography (HPLC) with fluorescence detection and 1-antroylnitrile (1-AN) as labeling reagent after immunoaffinity clean-up. Cereal samples were extracted with methanol/water (90:10, v/v), and the extracts were cleaned-up through commercially available immunoaffinity columns containing monoclonal anti-T-2 antibodies (T-2 test HPLC, Vicam). T-2 and HT-2 toxins were quantified by reversed-phase HPLC with fluorometric detection (excitation wavelength 381 nm, emission wavelength 470 nm) after derivatization with 1-AN. The monoclonal antibody showed 100% cross-reactivity with both T-2 and HT-2 toxin, and the immunoaffinity column clean-up was effective up to 1.4 microg of both toxins. The method was successfully applied to the analysis of T-2 and HT-2 toxins in wheat, maize and barley. Recoveries from spiked samples with toxin levels from 25 to 500 microg/kg ranged from 70% to 100%, with relative standard deviation generally lower than 8%. The limit of detection of the method was 5 microg/kg for T-2 toxin and 3 microg/kg for HT-2 toxin, based on a signal-to-noise ratio 3:1. HT-2 toxin was detected in ten naturally contaminated wheat samples out of 14 samples analyzed, with toxin levels ranging from 10 to 71 microg/kg; three of them contained also T-2 toxin up to 12 microg/kg.

Accumulation of type A trichothecenes in maize, wheat and rice by Fusarium sporotrichioides isolates under diverse culture conditions

Toxigenic isolates of Fusarium sporotrichioides were tested for the production of type A trichothecenes (T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol) when grown on three substrates (maize, rice and wheat) under various conditions of temperature and water activity in the laboratory for 3 weeks. Trichothecenes were determined by high-performance liquid chromatography with fluorescence detection, after derivatisation with coumarin-3-carbonyl chloride. This is the first time this analytical method has been applied to an extensive study of trichothecene accumulation. With minor exceptions, greater trichothecene production occurred when samples were incubated at 20 degrees C and moistened with 35% water (water activity 0.990) although incubation conditions affected the substrates studied in different ways. No correlation between the different pairs of trichothecenes was found except for neosolaniol and diacetoxyscirpenol (r=0.56). Principal component analysis results show that the data points can be grouped in three rough clusters related to cereal type, which points out that the composition of these cereals can influence the production of type A trichothecenes.

Occurrence of T-2 toxin in processed cereals and pulses in Turkey determined by HPLC and TLC

The purpose of this study was to investigate the T-2 toxin level of contaminated cereal and pulse products in Turkey. T-2 toxin was detected using high performance liquid chromatography (HPLC) with UV detection at 208 nm and thin layer chromatography (TLC) was used for confirmation of the T-2 toxin-contaminated samples (> or = 1 ppm). The recovery was 93 +/- 3.3% (SD 3.29, n = 5) for chickpea spiked with a known amount of T-2 toxin (1 ppm). The detection limits for T-2 toxin for HPLC and TLC were 25 ng per injection and 50 ng per spot, respectively. A total of 50 commercially available cereal and pulse product samples, collected from markets and street bazaars, were analysed. Incidences of T-2 toxin detected in cereal and pulse products were 23.5% and 31.2%, respectively and the maximum detected amount was 1.9 ppm in a sample of dried beans. The incidence of toxin-contaminated specimens is not so low relative to the volume of specimens produced.

Determination of T-2 toxin in grain and grain products by HPLC and TLC

The purpose of this study was to investigate the T-2 toxin contaminated grain and grain products consumed especially by Turkish population. The T-2 toxin was detected using the high performance liquid chromatography (HPLC) with UV detector at 208 nm and the identify of T-2 was further confirmed by thin layer chromatography (TLC). The recovery was 91 +/- 4.24% for corn flour fortified with the known amount of T-2 toxin (1 ppm). The detection limits of T-2 toxin for the HPLC and the TLC were 25 ng and 50 ng, respectively. A total of 30 commercially available grain and grain product samples were analyzed. Two corn flour samples were found to contain detectable levels of T-2 toxin at a level of 1.60 ppm and 4.08 ppm.

Taxonomic relationships among the toxigenic speciesFusarium acuminatum,Fusarium sporotrichioidesandFusarium tricinctumby isozyme analysis and RAPD assay

Isozyme and random amplified polymorphic DNA (RAPD) analyses have been used in combination with numerical taxonomy to study the taxonomic relationships among the toxigenic species Fusarium acuminatum Ellis & Everh. sensu Gordon (subsp. acuminatum and subsp. armeniacum), Fusarium sporotrichioides Sherb. and Fusarium tricinctum (Corda) Sacc. Eight enzymes, selected among 23 enzyme systems tested initially for activity, resolution, and consistent formation of bands, were used for isozyme analysis of 75 strains. Both cluster analysis grouping by average linkage method and correspondence analysis of the isozyme data set resulted in an arrangement of the four taxa inconsistent with their classical taxonomic classification in the Fusarium sections Gibbosum and Sporotrichiella. Isolates of F. acuminatum subsp. acuminatum were more closely related to F. tricinctum than to F. acuminatum subsp. armeniacum. Correspondingly, the F. acuminatum subsp. armeniacum group was closer to F. sporotrichioides than to F. acuminatum subsp. acuminatum. Twenty-seven strains of the four taxa, representative of the variability found by isozyme analysis, were studied using a RAPD analysis with five different decamer primers. All the primers produced polymorphic amplification patterns with taxon-specific bands, in addition to individual-specific bands. Correspondence analysis of the RAPDs distinguished four compact groups corresponding to the four taxa studied. These data support the separation of the varieties of F. acuminatum into two different species, and suggest a revision of the Fusarium sections Gibbosum and Sporotrichiella may be necessary. Key words: Fusarium, isozymes, RAPDs, numerical taxonomy, mycotoxins.

Determination of mycotoxins produced by Fusarium isolates from banana fruits by capillary gas chromatography and high-performance liquid chromatography

A method of analysis for trichothecenes (nivalenol, deoxynivalenol, 3- and 15-acetyldeoxynivalenol, diacetoxyscirpenol, neosolaniol, T-2 tetraol, T-2 and HT-2 toxins), zearalenone and zearalenols, and another method for determination of fumonisin B1 are described and applied to cultures of Fusarium isolated from bananas. Both methods were adapted from different techniques of extraction, clean-up and determination of these mycotoxins. The first method involves extraction with methanol-1% aqueous sodium chloride, clean-up of extracts by partition with hexane and dichloromethane, additional solid reversed-phase clean-up and analysis of two eluates by both high-performance liquid chromatography with ultraviolet detection and capillary gas chromatography. The method for fumonisin B1 implies extraction with aqueous methanol, concentration, clean-up with water and methanol on Amberlite XAD-2 column, formation of a fluorescent 4-fluoro-7-nitrobenzofurazan derivative and analysis by high-performance liquid chromatography with fluorescence detection. Both procedures give good limits of detection and recoveries, and are considered suitable for the detection and quantification of the studied toxins in corn and rice cultures of Fusarium spp. isolated from banana fruits.

Screening forFusarium toxigenic isolates using larvae ofGalleria mellonella

The toxicity of twenty-fourFusarium isolates was evaluated towards larvae ofGalleria mellonella by the antlfeedant activity of the autoclaved fungal culture incorporated into insect diet. Culturesof isolates belonging to F.sporotrichioldes, F. compactum andF. sambucinum, well known as capable to synthesize trichothecenes, showed high antifeedant activity (ca 60-70%); whereas controversial activity was showed byF. equiseti, F. proliferatum andF. solani cultures, and not significant activity was showed byF. oxysporum cultures. The G.mellonella larvae bioassay is suggested as a reliable sensitive Insectbioassay for screening fungal toxicity.

Toxicity of some Fusarium section Sporotrichiella strains in relation to mycotoxin production

The relationship between the toxicities of crude extracts and purified toxins of Fusarium spp. belonging to the section Sporotrichiella has been assessed. Toxicity was determined on the basis of death of Artemia salina larvae and of viability and blastogenic response of bovine and human lymphocytes. Trichothecene-producing strains of Fusarium sporotrichioides and Fusarium poae were toxic to A. salina and to lymphocyte blastogenesis. A strain of Fusarium tricinctum, producing visoltricin and chlamydosporol, induced differentiated activity in different bioassays (toxicity to A. salina but only minor activity against lymphocyte blastogenesis). Other, non-toxin-producing strains of Fusarium chlamydosporum, F. poae, and F. tricinctum were not active in the tested biosystems.

Cytotoxicity of trichothecene mycotoxins isolated from Fusarium sporotrichioides (MC-72083) and Fusarium sambucinum in baby hamster kidney (BHK-21) cells

Twenty-six trichothecene mycotoxins produced by Fusarium sporotrichioides (MC-72083) and Fusarium sambucinum were screened for relative cytotoxicity in cultured baby hamster kidney (BHK-21) cells. The relative cytotoxicity was measured as LC100. The most cytotoxic trichothecenes were T-2 toxin (5 ng/ml) and the recently isolated 4-propanoyl HT-2 (5 ng/ml) and 3'-hydroxy T-2 toxin (5 ng/ml). T-2 tetraol (1 x 10(4) ng/ml), 8-beta-hydroxytrichothecene (1 x 10(4) ng/ml), sporotrichiol (2 x 10(4) ng/ml), 8-oxodiacetoxyscirpenol (6 x 10(4) ng/ml) and 8-acetyl T-2 tetraol (1 x 10(5) ng/ml) were the least toxic of the regular trichothecenes. None of the modified trichothecenes or the apotrichothecene were very cytotoxic: 8-beta-hydroxysambucoin (2 x 10(3) ng/ml), FS-1 (5 x 10(3) ng/ml), 8-alpha-hydroxysambucoin (8 x 10(4) ng/ml) and trichotriol (1 x 10(5) ng/ml). The modified trichothecenes, FS-2 and FS-3, were not toxic even at 1 x 10(5) ng/ml. The baby hamster kidney cell bioassay proved to be a very sensitive and reproducible means of screening new trichothecene mycotoxins for relative cytotoxicity.

Fusarium species and their mycotoxins in infected corn in Italy

Surveys of corn (infected plants and commercial kernels) for Fusarium species and their mycotoxins were carried out on samples collected all over Italy and from some European and mediterranean countries. Investigations on samples of corn stalk and ear rot standing in the field, mainly collected in southern Italy, proved to be contaminated with zearalenone (ZON), zearalenols (ZOL), and deoxynivalenol (DON). The Fusarium species most frequently isolated, and their recorded toxigenic capability (in parentheses), were: F. moniliforme; F. culmorum (ZON, ZOL, DON, 3AcDON); F. equiseti (ZON, ZOL); and F. proliferatum (MF). Along with these species, F. graminearum group 2 (ZON, DON and/or 3AcDON or 15AcDON); F. chlamydosporum; F. acuminatum (type-A trichothecene derivatives); and F. semitectum were often found to be associated. F. heterosporum (ZON, ZOL); F. solani; F. crookwellense (ZON, ZOL, FUS, NIV); F. oxysporum (MF); F. avenaceum (MF); F. sporotrichioides (T-2 toxin and derivatives); and F. poae (DAS, MAS) were occasionally isolated.

Characterization of trichothecenes by ammonia chemical ionization and tandem mass spectrometry

Ammonia and deuterated ammonia chemical ionization (CI) mass spectra and collisionally activated dissociation (CAD) mass spectra of ammonium adduct ions are presented for ten trichothecenes. The samples were introduced by direct exposure probe. Effects of ion source temperature and pressure on the ammonia CI gas plasma and the formation of the ammonium adduct ion were studied. The CI conditions were optimized to produce a maximal yield for the ammonium adduct ion of trichothecenes, i.e. the parent ion for tandem mass spectral analysis. Besides source temperature and pressure, proton affinity and the stability of the ammonium adduct ion affect the relative abundance ratio of [M + H]+:[M + NH4]+ in ammonia CI and CAD mass spectra. The ratio [M + H]+:[M + NH4]+, and hence the stability of the ammonium adduct ion, are largely determined by the functional groups (hydroxy, carbonyl, acetoxy, and isovaleroyloxy) and their location in the trichothecene nucleus. The most abundant fragment ions in the ammonia CI spectra and the most abundant daughter ions in the CAD spectra of the ammonium adduct ions are formed by the losses of ammonia and functional groups as neutrals in various combinations.

Biosynthesis and preparation of T-2 Toxin, HT-2 Toxin and Neosolantol

Biosynthesis of trichothecenes by strains ofF. sporotriahioides KF 9 6 and KF 530 was performed on rice as a medium. Three toxins in significant amounts were produced, with yield: T-2 toxin 0.7g from 600g of drv culture, being the highest of the three metabolites, HT-2 toxin 0.06g an Neosolaniol 0.015g. Toxins were extracted with methanol from ground and defatted dry culture. Liquid/liquid partition, using chloroform/water saturated solution of sodium bicarbonate as a preliminary purification was applied. Silicagel and charcoal columns were used in further purification. Toxin were separated by preparative TLC and crystallized from methanol.

Phytotoxicity of metabolites formed by Fusaria to cereal seedlings

Phytotoxicity of 37 isolates of seven species ofFusarium has been studied. Metabolites of tested species exhibited signficantly different phototoxicity towards cereal seedlings. Germination was in greatest extent inhibited by metabolites ofF. subglutinans, in smallest extent by metabolites ofF. tricinctum /respectively 50% and 8%/. The growth rate of wheat seedlings was most strongly retarded by metabolites ofF. crookwellense, metabolites ofF. tricictum inhibited growth in the lowest percentage 57% and 29% respectively.