Production of fumonisins by Fusarium moniliforme strains from various substrates and geographic areas.

Strains of Fusarium moniliforme from different geographic areas and from corn and other substrates were tested for the ability to produce fumonisins in culture. The test results indicate that the potential exists for production of fumonisins by such strains in agricultural commodities and other substrates in widespread geographic areas.     

Production of fumonisins by Fusarium moniliforme strains isolated from corn grain

Fusarium moniliforme is the predominant fusarium species in the grain mycoflora of corn grown in Northern Caucasus, accounting for 95% of fusarium isolates. Eighty-five Fusarium moniliforme strains were grown on grain substrate and checked for the presence of fumonisins (B1 + B2 + B3) by indirect solid-phase enzyme immunoassay (EIA). All strains were capable of producing fumonisins (0.95 to 32,000 mg/kg). Strains sampled in the Krasnodar krai produced the highest fumonisin levels (averaging 5490 mg/kg).     

Production of fumonisins by Fusarium moniliforme and Fusarium proliferatum isolates associated with equine leukoencephalomalacia and a pulmonary edema syndrome in swine.

Fumonisin B1 (FB1) and FB2 were isolated from corn cultures of both Fusarium moniliforme and Fusarium proliferatum. Respective concentrations in culture materials of FB1 and FB2 ranged from 960 to 2,350 and 120 to 320 micrograms/g for F. moniliforme and from 1,670 to 2,790 and 150 to 320 micrograms/g for F. proliferatum. Thin-layer chromatography, gas chromatography-mass spectroscopy, high-performance liquid chromatography, and liquid secondary ion mass spectroscopy were used for detection. Fumonisins from F. proliferatum have not previously been reported.     

Production of Alanine by Fusarium moniliforme

Fusarium moniliforme grown in a chemically defined medium in submerged culture accumulated amino acids extracellularly. Alanine and glutamic acid were present in greatest amounts, with traces of glycine, lysine, threonine, and valine detectable. Increasing the glucose and urea concentrations of the medium increased yields of alanine. Further increases in alanine production occurred with elevated levels of mineral salts in the medium, whereas the addition of a vitamin mixture proved to be inhibitory. Chemical changes resulting from the growth of F. moniliforme in the final fermentation medium disclosed maximal alanine production, mycelial weight, and glucose consumption after 72 hr of incubation at 28.5 C. Total soluble nitrogen, by contrast, was minimal at the same time period. The pH remained in the alkaline range throughout the fermentation.     

Production of fumonisins by Fusarium moniliforme and Fusarium proliferatum isolates associated with equine leukoencephalomalacia and a pulmonary edema syndrome in swine

Fumonisin B1 (FB1) and FB2 were isolated from corn cultures of both Fusarium moniliforme and Fusarium proliferatum. Respective concentrations in culture materials of FB1 and FB2 ranged from 960 to 2,350 and 120 to 320 micrograms/g for F. moniliforme and from 1,670 to 2,790 and 150 to 320 micrograms/g for F. proliferatum. Thin-layer chromatography, gas chromatography-mass spectroscopy, high-performance liquid chromatography, and liquid secondary ion mass spectroscopy were used for detection. Fumonisins from F. proliferatum have not previously been reported.     

Inhibition of sphingolipid biosynthesis by fumonisins. Implications for diseases associated with Fusarium moniliforme

Culture materials and grains contaminated with certain isolates of Fusarium moniliforme cause equine leucoencephalomalacia, porcine pulmonary edema syndrome, and liver cancer in rats. The causative agents are thought to be a family of compounds called fumonisins, which bear considerable structural similarity to the long-chain (sphingoid) base backbones of sphingolipids. Incubation of rat hepatocytes with fumonisins inhibited incorporation of [14C]serine into the sphingosine moiety of cellular sphingolipids with an IC50 of 0.1 microM for fumonisin B1. In contrast, fumonisin B1 increased the amount of the biosynthetic intermediate sphinganine, which suggests that fumonisins inhibit the conversion of [14C]sphinganine to N-acyl-[14C]sphinganines, a step that is thought to precede introduction of the 4,5-trans double bond of sphingosine (Merrill, A.H., Jr. and Wang, E. (1986) J. Biol. Chem. 261, 3764-3769). In agreement with this mechanism, fumonisin B1 inhibited the activity of sphingosine N-acyltransferase (ceramide synthase) in rat liver microsomes with 50% inhibition at approximately 0.1 microM and reduced the conversion of [3H]sphingosine to [3H]ceramide by intact hepatocytes. As far as we are aware, this is the first discovery of a naturally occurring inhibitor of this step of sphingolipid metabolism. These findings suggest that disruption of the de novo pathway of sphingolipid biosynthesis may be a critical event in the diseases that have been associated with consumption of fumonisins.     

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.     

Study of the biosynthesis of fumonisins B1, B2 and B3 by different strains of Fusarium moniliforme

The relationship between fungal growth and the production of fumonisin on maize grain by 25 strains of Fusarium moniliforme of different origins has been investigated. Although sporulation was essentially the same for all the strains (about 10⁸ propagules g⁻¹ dry matter), ergosterol assays revealed marked variations in fungal biomass. All strains studied produced highly variable amounts of fumonisin B1, the highest levels being observed in strains of ergosterol content above 400 μg g⁻¹. However, no correlation could be established between the synthesized biomass and the quantity of fumonisins produced. We verified that ergosterol is an indicator of mycelial growth, and therefore of the potential toxicity of the analysed grain.     

Production of Fumonisins by Fusarium moniliforme Strains Isolated from Corn Grain

Fusarium moniliforme is the predominant fusarium species in the grain mycoflora of corn grown in the northern Caucasus, accounting for 95% of fusarium isolates. Eighty-five Fusarium moniliforme strains were grown on a grain substrate and checked for the presence of fumonisins (B₁ + B₂ + B₃) by indirect solid-phase enzyme immunoassay. All strains were capable of producing fumonisins (0.95 to 32 500 mg/kg). Strains sampled in Krasnodar krai produced the highest fumonisin levels (averaging 5490 mg/kg). Fusarium moniliforme strains were subdivided into three morphological types. The types differed significantly in the rate of fumonisin production. Strains belonging to the mycelial type (I) produced the greatest amount of the toxin, and those of the pionnotal type (III) were the least active. Strains of the sporodochial type (II) had an intermediate activity. The mean levels of fumonisin accumulation (mg per kg) for each type were I, 7460; II, 1150; and III, 227.     

不同地理和寄主来源的串珠镰孢的营养体亲和性研究

选用107个采自安徽、山东、江苏、湖北等不同地区棉花、玉米、水稻的串珠镰孢Fusarium moniliforme菌株,在含KClO3培养基上诱导筛选获得抗氯酸盐、不能还原利用硝酸盐的突变株(nitmutant)1081株,在MM、NM、HM等3种不同氮源培养基上划分出nitA、nitB、nitC、nitD四种突变类型,其中nitA出现频率最高,占总体76%;nitB和nitC其次,分别占12%和10%;nitD最少,占总体2%。采用nit突变体互补型配对技术,将供试菌株分别按地理来源和分离寄主进行配对培养,测得不同寄主群体内菌株的营养体亲合群(VCGs)数为56个,然后从每个VCG中随机抽取1个样本菌株,测定不同群体间菌株的VCG同一性,发现所抽取的56个菌株分属于54个VCGs,其中来自棉花的菌株Fm1、Fm2分别与来自玉米的菌株Fm19、Fm20属于同一VCG。按地理来源测定,4个群体共测得55个VCGs,其中来自山东的菌株Fm45和来自安徽的菌株Fm16发生亲和反应,属于同一VCG;107个菌株划分为54个VCGs。结果表明,串珠镰孢菌株群体内存在丰富的VCGs多样性。经多样性分析,不同地理来源的菌株平均1.9454个组成1个VCG,其P与Shannon-Wiener多样性指数分别为0.5140和1.0365;不同寄主上分离的菌株平均1.9107个形成1个VCG,P与Shannon-Wiener多样性指数分别为0.5234和0.9048。经t测验,两个群体Shannon-Wiener多样性指数H值间差异不显著(t=0.70小于t0.05=1.98),说明两个群体的VCG多样性无显著差异,相同地区来源的菌株的遗传相似性与相同寄主来源的遗传相似性相当。     

Production of fusarin C on cereal and soybean by Fusarium moniliforme.

Two isolates of Fusarium moniliforme were compared with respect to production of a mutagenic compound, fusarin C, on seven corn varieties as well as on soybean, wheat, rye, barley, and a liquid culture medium. The isolates were originally obtained from corn and barley. Both isolates produced fusarin C on seed of all five crops within a 21-day period, and one isolate produced the largest amount on oats. Soybean was the poorest substrate for both isolates. Although the quantity of fusarin C produced on grain was isolate dependent, specific substrate requirements for each strain were suggested. The isolates differed in their ability to grow and produce fusarin C on corn with different moisture contents (16, 20, 24, and 28%). One isolate was more xerotolerant and grew at 16% moisture but did not produce the mutagen.     

Production of Fumonisins by Fusarium moniliforme Cultures Isolated from Jimsonweed in Mississippi

Eight Fusarium spp. were isolated from greenhouse-grown jimsonweed (Datura stramonium L.) in Mississippi in 1990. Four isolates of Fusarium moniliforme were obtained and when grown on autoclaved rice, produced 115 to 3,200 mg/kg fumonisin B₁, (FB₁). Other fumonisin-related compounds, such as FB₂, FB₃ and FB₄ were also produced at levels of 240, 210 and 160 mg/kg, respectively. F. semitectum (1 isolates) was negative for production of fumonisin and other phyto-toxins. F. oxysporutn (1 isolate) produced only 3.5 g/kg moniliformin. This is the first report of production of fumonisins by F. moniliforme isolated from weeds such as jimsonweed.     

D-泛解酸内酯水解酶产生菌的筛选及产酶条件研究

筛选到一株产D 泛解酸内酯水解酶的菌株 ,经鉴定为串珠镶孢霉菌 (Fusariummonili forme)SW 90 2。产酶条件研究表明 ,用甘油作碳源 ,蛋白胨作氮源 ,初始pH8 0 ,温度 2 6℃ ,摇瓶培养 3d ,产酶量最高。在 6 0L发酵罐中通风发酵 45h ,产菌丝体生物量 7 1 8g干菌体 L ,D 泛解酸内酯水解酶酶活力达到 0 92IU g干菌体     

D-泛解酸内酯水解酶产生菌的筛选及产酶条件研究

筛选到一株产D-泛解酸内酯水解酶的菌株,经鉴定为串珠镶孢霉菌（Fusarium monili-forme)SW-902。产酶条件研究表明,用甘油作碳源,蛋白胨作氮源,初始pH8.0,温度26℃,摇瓶培养3d,产酶量最高,在60L发酵罐中通风发酵45h,产菌丝体生物量7.18g干菌体/L,D-泛解酸内酯水解酶酶活力达到0.92IU/g干菌体。     

Dimorphic fungus characteristic of fumonisin-producing strains of Fusarium moniliforme from Zhejiang

Fusarium moniliforme and its fumonisins have been shown to be carcinogenic in lab animals and have been linked to high incidences of human esophageal cancer. In this study we report the dimorphic fungus characteristic of fumonisin-producing strains of F. moniliforme from foodstuffs in Zhejiang, China. All of the twenty strains of F. moniliforme shown produce fumonisin B₁ 475.9–6322.2 μg/g in corn medium. These strains of F. moniliforme form yeast-like colonies in Sabouraud's agar plates contained 9% NaCl at 37 °C incubator and shows mostly budding reproduction. In blood agar plates these strains of F. moniliforme appear grass-green haemolytic reactions. This is the first report that yeast-like growth, dimorphic pathogenic fungus feature is found in F. moniliforme. These results suggest that it is also important to program epidemiological surveys of F. moniliforme as a primary pathogenic fungus, while proceeding to produce mycotoxins of F. moniliforme in food hygiene. This revised version was published online in August 2006 with corrections to the Cover Date.     

Fumonisin production and other traits of Fusarium moniliforme strains from maize in northeast Mexico.

Strains of Fusarium moniliforme from maize seed collected in four fields in northeast Mexico were tested for fumonisin production in culture, for sexual compatibility, and for vegetative compatibility by using non-nitrate-utilizing mutants. The test results indicate that a diverse population of fumonisin-producing strains of F. moniliforme (Gibberella fujikuroi) mating population A predominates and that a potential exists for production of fumonisins in Mexican maize.     

Production of fusarin C on cereal and soybean by Fusarium moniliforme

Two isolates of Fusarium moniliforme were compared with respect to production of a mutagenic compound, fusarin C, on seven corn varieties as well as on soybean, wheat, rye, barley, and a liquid culture medium. The isolates were originally obtained from corn and barley. Both isolates produced fusarin C on seed of all five crops within a 21-day period, and one isolate produced the largest amount on oats. Soybean was the poorest substrate for both isolates. Although the quantity of fusarin C produced on grain was isolate dependent, specific substrate requirements for each strain were suggested. The isolates differed in their ability to grow and produce fusarin C on corn with different moisture contents (16, 20, 24, and 28%). One isolate was more xerotolerant and grew at 16% moisture but did not produce the mutagen.     

Production of fumonisin B1 by Fusarium moniliforme NRRL 13616 in submerged culture.

Fumonisin B1, a recently discovered mycotoxin, was synthesized by submerged cultures of Fusarium moniliforme NRRL 13616 grown for 29 days at 28 degrees C and 220 rpm in a basal salts medium (pH 5.0) supplemented with 90 g of glucose per liter and 3.5 g of ammonium sulfate per liter. Under these culture conditions, 74 +/- 23 micrograms of fumonisin B1 per ml was produced by 29-day-old F. moniliforme NRRL 13616 cultures. Fumonisin B1 was detected in liquid culture extracts by high-performance thin-layer chromatography. Fumonisin B1 was confirmed and quantitated by gas chromatography and gas chromatography-mass spectral analysis of the trimethylsilyl derivative. The use of a defined medium for producing fumonisin B1 in a submerged culture facilitates its isolation and provides an excellent method for conducting biosynthetic studies.