Natural occurrence of fumonisins and their correlation to Fusarium contamination in commercial corn hybrids growth in Argentina

Fifty commercial corn hybrids with different endosperm characteristics, vegetative cycle length and cross class grown in the same geographical area (Cordoba Province, Argentina) were analysed for fumonisin accumulation. All hybrids analysed showed fumonisin B₁ and B₂ contamination ranging from 185 to 27,050 ng/g for FB₁ and from 40 to 9950 ng/g for FB₂. Although most of the hybrids analysed had flint-type endosperm, two hybrids with dent-type endosperm (e.g. Prozea 10 and AX 746) showed the highest level of fumonisin (37,000 ng/g) and more FB₂ than FB₁ (FB₂/FB₁ ratio 2.42), respectively. There was no correlation between fumonisin concentration and length of the vegetative cycle. Among 18 hybrids examined for Fusarium species contamination there was also no correlation between fumonisin contamination and the level of infection with Fusarium species (Section Liseola). Eighteen hybrids showed fumonisin levels lower than 1000 ng/g. This result suggests that there is some possibility of selecting hybrids resistant or less susceptible to fumonisin and Fusarium contamination.     

Isolation of beauvericin as an insect toxin from Fusarium semitectum and Fusarium moniliforme var. subglutinans

Nonpolar methylene chloride-soluble extracts from the mycelia of Fusarium semitectum and Fusarium moniliforme var. subglutinans were toxic to Colorado potato beetles. The major toxic metabolite was isolated and found to be the cyclodepsipeptide, beauvericin. This is the first report of the isolation of beauvericin from the genus Fusarium.     

A new fumonisin from solid cultures of Fusarium moniliforme

A new fumonisin has been isolated from Fusarium moniliforme isolate MRC826 grown on corn. It was shown by NMR and mass spectrometry to be an isomer of fumonisin B₂ that has free hydroxyl groups at C-3 and C-10 instead of the normal C-3 and C-5. This new fumonisin was detected in cultures of most isolates of F. moniliforme that were examined and was usually present at concentrations similar to those of fumonisin B₂. Two isolates of F. moniliforme that produce significantly higher levels of this new isomer were identified.Abbreviations ELEM equine leukoencephalomalacia Mention of companies or products by name does not imply their endorsement by the US Department of Agriculture over others not cited.     

Biosynthesis of labeled fumonisins in liquid cultures of Fusarium moniliforme

Fumonisins were readily produced in cultures of Fusarium moniliforme using a defined liquid medium. Addition of 200 mg of d₃-methyl L-methionine to 100-ml cultures of F. moniliforme gave increased overall yields and high levels of deuterium (²H) incorporation into fumonisin B₁. Approximately 90% of the resulting fumonisin B₁ contained 6 deuterium atoms, while 9% of the product contained 3 deuterium atoms. Deuterium was shown to be incorporated exclusively in the methyl groups of the fumonisin backbone. The addition of as little as 5 mg of labeled methionine stimulated fumonisin production, but only about 5% of the fumonisin produced contained 3 deuterium atoms.Abbreviations ELEM equine leukoencephalomalacia Mention of companies or products by name does not imply their endorsement by the US Department of Agriculture over others not cited.     

Interactions of Fusarium moniliforme,its metabolites and bacteria with corn

Fusarium moniliforme Sheldon is an economically important pathogen of corn (Zea mays L.) which causes stalk, root and ear rot. Several mycotoxins have also been isolated, identified and implicated in both animal and human toxicoses. The fungus can be disseminated in symptomless corn seed and can also survive in crop residues in the soil. Asymptomatic infection may be related to different corn cultivars, fungal strains, and environmental factors. Symptomatic expression of pathogenicity may vary, but usually the result of such infections is death of the plant. The greatest concern is the asymptomatic infection, since it is in this form that fungal toxins may surreptitiously enter animal and human food chains. F. moniliforme produces both fusaric acid, which is phytotoxic to corn and interferes with seed germination, and plant growth regulators that may affect pathogenicity of the fungus or be associated with the production of mycotoxins. Other metabolites, including fusarin C, moniliformin, and the fumonisins, may or may not be phytotoxic, but are associated with animal and human toxicoses. The control of F. moniliforme in corn is therefore quite important. One potential means to accomplish this reduction is biocontrol by the application of antagonistic rhizobacteria to corn kernels at planting. To be effective the bacteria must be able to colonize the corn root system and be able to prevent root infection by successful competing with F. moniliforme which may be accomplished by siderophore and or antibiotic activity.     

Characterization of gibberellin producing strains of Fusarium moniliforme based on DNA polymorphism

The gibberellins are one of the major groups of growth promoting hormones and are secondary metabolites of the fungus Fusarium moniliforme (Perfect stage: Gibberella fujikuroi). Sixteen strains of Fusarium from different geographical regions and different hosts were analysed for their ability to produce gibberellins (GA) and for genetic relatedness by random amplified polymorphic DNA (RAPD). Range of gibberellin production varied between 28.9 to 600.0 mg g^-1 dry weight of mycelium in different strains of Fusarium. RAPD analysis showed completely different pattern between high, moderate and low producing strains. High producers formed nearly identical RAPD patterns, whereas the low and moderate producers gave heterologous amplification patterns. Since Fusarium pallidoroseum was in another group, it was possible to distinguish between different species of the genus Fusarium by RAPD. These investigations may find an application in the diagnosis of unknown Fusarium species and in distinguishing isolates of Gibberella fujikuroi within the section of Liseola. This revised version was published online in June 2006 with corrections to the Cover Date.     

Purification and biochemical characterization of polygalacturonase II produced in semi-solid medium by a strain of Fusarium moniliforme

A strain of Fusarium moniliforme isolated from a tropical mangrove ecosystem near Mumbai, India and deposited in the National Collection of Industrial Microorganisms (NCIM) as F. moniliforme NCIM 1276. The organism produced a single extracellular polygalacturonase (PG I) [EC 3.2.1.15] at pH 5 and a single pectate lyase (PL) [EC 4.2.2.2] at pH 8 in liquid medium containing 1% citrus pectin. Growth on semi-solid medium containing wheat bran and orange pulp resulted in a three-fold increase in PG production and a two-fold increase in PL production in comparison with that in liquid medium. The increased production of PG on semi-solid media, as compared to production in liquid media was investigated. The increased production of PG was partly due to the expression of a second polygalacturonase (PG II) isoenzyme by the fungus which was biochemically different from the one produced in liquid medium. The second PG II was a 30.6kDa enzyme, had an alkaline pI of 8.6, the Km was 0.166mg ml(-1), Vmax 13.33 micromol min(-1) mg(-1) and the kcat was 403 min(-1). It had a specific activity of 18.66U mg(-1). The differences between the PGs (PG I and PG II) suggest that the two enzymes are the products of different genes. The fungus also produced the same two PGs when it infected Lycopersicon esculentum (tomato). Only one PL was produced irrespective of growth conditions.     

Molecular characterization of endophytic strains of Fusarium verticillioides (= Fusarium moniliforme) from maize (Zea mays. L)

The species Fusarium verticillioides (= F. moniliforme) is often found in maize seeds, constituting an important source of inoculum in the field. Fusarium spp., associated with symptomatic and asymptomatic plants, may be a primary causal agent of disease, a secondary invader or an endophyte. In the present work, endophytic fungi were isolated from two populations of Zea mays (BR-105 and BR-106) and their respective inbred lines. Within different inbred lines of maize, Fusarium was found at a frequency of 0 to 100% relative to the number of total isolated fungi. The frequency with which the genus occurred was practically the same in the two field sites (around 60%). Twenty-one F. verticillioides strains were analysed using the random amplified polymorphic DNA (RAPD) technique, employing 10 random primers. Variability analysis of endophytic isolates via RAPD showed genome polymorphism taxa of species around 60%. Endophytic isolates were clustered by their sites of origin. RAPD analysis clustered the endophytic isolates by their maize inbred lines hosts (Mil-01 to Mil-06), whereas at site A they clustered into two major groups related to the maize gene pool (BR-105 or BR-106 population). All strains isolated from seeds collected in Site A, except strains L9 and L10, were sub-grouped according to maize inbred lines. The analysis showed a discrete sub-grouping at site B. Results obtained here could be explained by a co-evolution process involving endophytic isolates of F. verticillioides and maize inbred lines.     

Effect of climatic conditions on natural mycoflora and fumonisins in freshly harvested corn of the State of Paraná, Brazil

Natural mycoflora associated with fumonisins were analyzed in 150 samples of freshly harvested corn from Central-Southern, Central-Western and Northern regions of the State of Paraná, Brazil and correlated to climatic conditions. The corn samples were frequently contaminated with Fusarium sp.(98.7 to 100%) and Penicillium sp. (93 to 100%), when compared to Aspergillus sp. (not detected to 27.7%). The highest contamination with potentially mycotoxigenic fungi occurred in corn harvested in the Central-Western region, where total mould and yeast counts ranged from 5.5 × 10³ to 5.2 × 10⁶ CFU/g, with 98.7% contaminated byFusarium sp. and 93% by Penicillium sp. In this region F. moniliforme (F. verticillioides) was the predominant Fusariumsp., and was isolated in 85.9% of the samples. Aspergillus sp. was isolated from 27.7% samples. FB₁ was detected in 100% of the samples (mean of 2.39 g/g) and FB₂ in 97.7% (mean of 1.09 g/g). Fumonisins were also detected in all samples from Northern region, with mean of 4.56 g/g (FB₁) and 2.20 g/g (FB₂).Considering 1.0 g/g as the threshold, 72% of the corn samples from the Central-West and 92% from the North were contaminated with concentrations above this value, in contrast to a 18.5% contamination rate from Central-Southern samples. Between corn planting to harvesting season, the average maximum temperature and relative humidity were 26 °C and 77.1%(Central-Southern), 27 °C and 69% (Northern)and 29.9 °C and 89.1% (Central-Western).Therefore, the higher fumonisins contamination of corn from Northern region when compared to the Central-South were due to the differences in rainfall levels (92.8 mm in Central-Southern, 202 mm in Northern) during the month preceding harvest.This revised version was published online in October 2005 with corrections to the Cover Date.     

Lipid-to-gibberellin metabolic switching in Fusarium moniliforme via the action of sesamol

Sesamol (3,4-methylenedioxyphenol) at 2.5 mM inhibited growth of Fusarium moniliforme by about 40% and lipid accumulation by 35%. Gibberellin (GA₃) accumulation was increased by 20-fold, to 63 mg g^–1 biomass, in the presence of sesamol indicating that the acetyl-CoA destined for fatty acid biosynthesis was now being switched into secondary metabolite (GA₃) accumulation. Synthesis of other metabolites from acetyl-CoA, such as bikaverin and carotenoids, though were not increased in the presence of sesamol. Metabolic switching is therefore feasible by judicious use of selected inhibitors that can thus block primary metabolic routes but which do not affect secondary metabolites.     

Protection of maize seedlings byFusarium moniliforme against infection byFusarium graminearum in the soil

The incidence ofFusarium moniliforme in surface-sterilized kernels in two commercial South African white maize cultivars was 64% and 6%, respectively. Heat treatment completely eliminated seedborneF. moniliforme from kernels of both cultivars. Heat treated, uncontaminated maize germlings were pre-inoculated with different isolates ofF. moniliforme and planted in steam-treated soil containing inoculum of different isolates ofF. graminearum Group 1 and Group 2. Seedling weights of germlings pre-inoculated with some isolates ofF. moniliforme were significantly higher than those of controls when exposed to some isolates ofF. graminearum in the soil. The protective effect of pre-inoculation withF. moniliforme was particularly evident in maize seedlings exposed to inoculum of an aggressive isolate ofF. graminearum Group 1. This is the first report of the protection of maize seedlings byF. moniliforme against infection byF. graminearum in the soil.     

Factors affecting gibberellic acid production by Fusarium moniliforme in solid-state cultivation on starch

The production of gibberellic acid (GA₃) by Fusarium moniliforme M-7121 in solid-state culture was evaluated in flask cultures as well as in 3-I horizontal rotary reactors. The highest production rate of GA₃ was with 80% (w/v) maize flour mixed with wheat bran. The optimum initial moisture content was inversely dependent on the ambient relative humidity. The initial water activity range for optimal growth and GA₃ accumulation was about 0.98 to 0.99, which is unusually high for a filamentous fungus. A low O₂ concentration resulted in a much decreased GA₃ yield and the appearance of a yellow to reddish pigmentation in the mycelium. The lag phase was short and rapid growth continued for up to 2 days in the rotary reactor, with a maximum specific growth rate of 0.12 h^–1. The maximum rate of GA₃ production occurred during the subsequent 3 to 10 days of incubation and the final GA₃ concentration reached was 18.7 mg to 19.3 mg/g dry culture. The point of maximum GA₃ accumulation after 10 to 12 days of incubation was usually marked by a sharp increase in pH.The authors are with the Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, 9300 Bioemfontein, Republic of South Africa     

玉米种质和新品种对腐霉茎腐病和镰孢穗腐病的抗性分析

玉米是我国最重要的农作物之一,腐霉茎腐病和镰孢穗腐病是玉米生产上的重要病害。2006-2012年期间,对1647份玉米种质进行了抗肿囊腐霉茎腐病和拟轮枝镰孢穗腐病鉴定,筛选出高抗茎腐病和穗腐病的种质分别为564份和27份,占鉴定总材料的34.2%和1.6%,抗性材料分别为209份和352份,占比为12.7%和21.4%,表明高抗肿囊腐霉茎腐病的资源较为丰富,高抗镰孢穗腐病的种质相对匮乏。其中,13份种质对2种病害均表现高抗,207份种质对2种病害均表现抗性或对其中一种表现高抗而另一种表现抗性。自交系中对肿囊腐霉茎腐病和拟轮枝镰孢穗腐病表现抗性以上(含HR和R)的种质分别占总鉴定种质的56.5%和23.6%,在农家种中分别为21.2%和21.4%,表明玉米自交系中的抗性资源较农家种丰富。2009-2013年期间参加国家玉米区试的品种中,对腐霉茎腐病表现高抗、抗性、中抗、感病和高感的品种分别占11.5%、11.9%、40.1%、17.6%和18.9%。2009-2011年间,中抗以上的育成品种所占比例呈现明显上升趋势,但2012-2013年间,中抗以上的品种所占比例呈下降趋势。     

Subchronic toxicological investigations of Fusarium moniliforme-contaminated corn,culture material,and ammoniated culture material

The fungus Fusarium moniliforme is ubiquitous on corn throughout the world and is a likely co-contaminant on corn infested with aflatoxin-producing Aspergillus flavus. Ammoniation has been used to detoxify aflatoxin-contaminated commodities. To determine the effect of ammoniation on the toxic potential of Fusarium moniliforme, male Sprague-Dawley rats were fed either diets containing 10% sound corn, ammoniated corn, corn culture material of hepatotoxic F. moniliforme strain MRC 826 (CM), or ammoniated CM for four weeks. They were observed for signs of toxicity and hematological, serum chemical and histopathological evaluations were made. Groups of male Balb/c mice were fed diets fortified with 10% sound corn or CM for four weeks and evaluated by serum chemical and histopathological means to determine the suitability of mice as a model species for investigation of F. moniliforme-induced hepatotoxicity. Ammoniation was ineffective for detoxification of the CM. Hepatotoxicity and renal toxicity of CM and ammoniated CM were qualitatively similar, although renal tubular lesions appeared more advanced in rats fed ammoniated CM. Adrenal cortical cellular vacuolation was also found in CM and ammoniated CM-fed rats, while focal seminiferous tubular degeneration and aspermia were found only in the testes of ammoniated CM-fed rats. Fumonisin B₁ concentrations of the CM and ammoniated CM diets averaged 99 and 75 ppm, respectively. CM containing 99 ppm fumonisin B₁ also produced hepatotoxicity in mice similar to that found in CM-fed rats. Thus, mice may be useful for investigations of F. moniliforme-induced hepatotoxicity.Mention of a trademark, proprietary name or vendor does not imply its approval by the US Department of Agriculture to the exclusion of others that may also be suitable.     

Occurrence of fumonisin B1 and B2 in corn-based foodstuffs in Taiwan market

Corn-based human foodstuffs purchased in Taiwan were analyzed for fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) using high-performance liquid chromatography. Fifty-two (33.9%) and 32 (20.9%) of 153 samples were found to contain FB₁ (73–2395 ng/g) and FB2 (120–715 ng/g), respectively. The highest frequency of detection and also the highest FB1 concentrations were found in sweetcorn (50%, 1089 ng/g) and cornflour (50%, 608 ng/g), followed by corn snacks (33.3%, 2395 ng/g), miscellaneous corn products (33.3%, 73 ng/g), popcorn (31.8%, 1003 ng/g) and cornflakes (23.5%, 1281 ng/g). 16 corn snacks (= approximately 20.5% of the samples) had an average FB₁ and FB₂ content of 456 and 145 ng/g, respectively, while six sweetcorn (= 25%) samples were contaminated with an average of 400 ng/g of FB₁ and 65 ng/g of FB₂. Of the 22 pop-corn samples examined, 7 had an average of 347 ng/g and 116 ng/g of FB₁ and FB₂, respectively. During an analysis of the distribution pattern for the combined fumonisin levels of FB₁ and FB₂, it became apparent that more than 69% of tested samples had fumonisin concentrations below 100 ng/g, while 11.1% (or 17 samples) contained in excess of 600 ng toxins per g. These results clearly illustrated that commercially available corn-based foodstuffs for human consumption in Taiwan are frequently contaminated with FB₁ and FB₂.This revised version was published online in October 2005 with corrections to the Cover Date.     

A review and update of animal toxicoses associated with fumonisin-contaminated feeds and production of fumonisins by Fusarium isolates

During the 1989 corn harvest season, numerous reports of equine leukoencephalomalacia (ELEM) outbreaks and a pulmonary edema (PPE) syndrome in swine from several regions of the United States were received by the National Veterinary Services Laboratories (NVSL), Ames, Iowa. Previous and concurrent research linked Fusarium moniliforme and fumonisin-contaminated feeds to both diseases. Chemical and mycological investigations revealed fumonisin B₁ (FB₁) concentrations of 20 to 360 ppm in suspect swine feeds and 8 to 117 ppm in suspect equine feeds. Nonproblem feeds contained concentrations below 8 ppm. Fusarium moniliforme and Fusarium proliferatum were isolated from both problem and nonproblem equine and swine feeds. When cultured on autoclaved corn, the F. moniliforme and F. proliferatum isolates produced respective FB₁ and fumonisin B₂ (FB₂) that range from less than 5 to more than 2450 ppm and less than 5 to more than 1000 ppm, respectively. Isolates from both problem and nonproblem feeds produced high levels (greater than 500 ppm) in culture. Reported here is a review of chemical and mycological data resulting from the study of several cases of PPE and ELEM.     

Comparative studies of hepatotoxicity and fumonisin B1 and B2 content of water and chloroform/methanol extracts of Fusarium moniliforme strain MRC 826 culture material

Fusarium moniliforme has been associated with several diseases including equine leukoencephalomalacia, human esophageal cancer and hepatotoxicity/hepatocarcinogenicity in laboratory animals. The potential health risks to animals and humans posed by F. moniliforme contaminated grains cannot be assessed until the toxins are identified and toxicologically evaluated. As part of a systematic approach to identifying the hepatotoxins produced by F. moniliforme, diets containing aqueous and chloroform/methanol (11) extracts of F. moniliforme strain MRC 826 culture material (CM) and/or the extracted CM residues were fed to male Sprague-Dawley rats for four weeks. Serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase activities were increased after two and four weeks and microscopic liver lesions were found in those animals fed aqueous CM extract and the CM residue after chloroform/ methanol extraction. Fumonisins B₁ and B₂ were extracted from the CM by water, but not chloroform/ methanol, and were present in the toxic diets at concentrations of 93–139 and 82–147 ppm, respectively. Nontoxic diets contained 22 ppm fumonisin B₁ and 65 ppm fumonisin B₂.Abbreviations CM culture material - ELEM equine leukoencephalomalacia Mention of a trademark, proprietory name or vendor does not imply its approval by the US Department of Agriculture to the exclusion of others that may also be suitable.     

Toxicity and moniliformin production by four recently described species of Fusarium and two uncertain taxa

Four recently described species, Fusarium nygamai, F. dlamini, F. beomiforme and F. napiforme and two uncertain taxa, F. nygamai from millet in Africa and Fusarium species from rice with Bakanae disease, were tested for toxicity and moniliformin production. Cultures grown on autoclaved corn were fed to groups of four one-day-old ducklings for 14 days. Isolates that caused the death of 3 or 4 out of 4 ducklings were considered to be toxic and analyzed for moniliformin. All 15 isolates of F. dlamini tested were nontoxic. The other taxa contained some isolates that were toxic to ducklings and produced moniliformin in corn cultures. This is the first report of moniliformin production by F. beomiforme (200–890 g/g), and F. napiforme (16–388 g/g), and by F. nygamai not obtained from millet in Africa (15–874 g/g). The highest production of moniliformin was obtained from the 19 isolates of F. nygamai from millet in Africa (4300–18200g/g) and the 15 isolates from rice with Bakanae disease (2300–19300 g/g). The taxonomic position of these two uncertain taxa should be re-evaluated.     

Mycoflora and fumonisin-producing strains ofFusarium moniliforme in mixed poultry feeds and component raw material

In a survey of the mycoflora and mycotoxins in foods and feeds, 66 samples of mixed poultry feeds and some component raw materials were investigated. Fungal counts ranged from < 10² to 1.3 × 10⁶ CFU/g.Fusarium spp. counts ranged from 10² to 1.0 × 10⁶ CFU/g. TheFusarium spp. strains isolated were screened for their potential to produce fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) in maize cultures. Samples and maize cultures were analysed for FB₁ and FB₂ using TLC and fluorescamine-derivative HPLC. No fumonisins were detected in the samples (<6 ppm).Fusarium moniliforme was isolated in 59.1% of samples, and 97.4% of the strains produced FB₁ and 79.4% of strains produced FB₂ in maize cultures. Some isolates produced higher FB₁ and FB₂ levels than the reference strainF. moniliforme MRC 826.