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Abstract

Twenty-three Fusarium culmorum and 21 F. graminearum isolates were studied for their ability to produce mycotoxins and other secondary metabolites. The strains were cultivated on rice, and the extracts analysed by gas chromatography mass spectrometry (GC-MS) after derivatization with pentafluoropropionic (PFP) reagent. Two F. culmorum strains formed nivalenol and its acetylated derivatives (chemotype II), while all F. graminearum and the other F. culmorum isolates produced deoxynivalenol (DON) via 3-acetyldeoxynivalenol (3-acetyl-DON) (chemotype IA). 15-hydroxy-culmorin, followed by 5-hydroxy-culmorin were the main other metabolites produced F. culmorum, while 5-, 12- and an unidentified hydroxy-culmorin, suggested to be 14-hydroxy-culmorin, were the main metabolites of F. graminearum. The hydroxy-culmorin profile was found to be significantly different for the two Fusarium species. Minor amounts of about ten other hydroxy-culmorins, four hydroxy-culmorones and 3,13-dihydroxy- epiapotrichothecene were also detected in most cultures. Traces of sambucinol seemed to be present in some of the isolates, but were not detected in any significant amounts. The precursors in the biosynthetic sequence to 3-acetyldeoxynivalenol, 7,8-dihydroxycalonectrin and 15-deacetyl-7,8-dihydroxycalonectrin, were detected in most cultures. We also report the assignment of both the 1H and 13C NMR data of 15-deacetyl-7,8-dihydroxycalonectrin, which has only been reported incorrectly before.

Terpenes from Marine-Derived Fungi

“…Culmorin and its hydroxylated congeners, but not isoculmorin, are widely distributed in various terrestrial Fusarium species, commonly found as pathogens on cereal crops [60,61]. Very often they co-occur with thrichotecenes such as deoxynivalenol (DON), which are also sesquiterpenes, but are characterised by a heavily rearranged and oxygenated carbon framework.…”

Orthoesters versus 2‐O‐Acyl Glycosides as Glycosyl Donors: Theorectical and Experimental Studies

“…1). 7 Culmorin analogues have been shown to contribute to the cytotoxicity of F. graminearum and F. culmorum cultures, but their importance as natural pollutants of feed and food is presently unknown 8…”

Hydroxylation of Longiborneol by a Clm2-Encoded CYP450 Monooxygenase to Produce Culmorin in Fusarium graminearum

“…3 F. culmorum isolates produced more 5-hydroxyculmorin and 15-hydroxyculmorin than culmorin, whereas F. graminearum isolates produced more culmorin than 5-hydroxyculmorin and 12-hydroxyculmorin. 3 In wild-type F. graminearum 9F1, the presence of 5-, 12-, and 15-hydroxyculmorin, detectable in the extracted ion chromatogram (EIC) ( Figure 4B), was dwarfed by the high abundance of culmorin (2) ( Figure 4A), suggesting that in this strain the Clm2-encoded CYP450 displayed superior enzymatic activity to the unidentified, possibly promiscuous C-5, C-12, and C-15 oxygenases. Assuming Clm2 encodes an exclusive CYP450 oxygenase, its disruption would leave the possibly nonspecific C-5, C-12, and C-15 oxygenases fully functional and still able to hydroxylate longiborneol.…”

“…Figure 1B shows the Southern analysis of the 11 transformants using both the 5′ and 3′ gene flanking sequences as probes. Only the six ΔClm2 disruptants numbered 3,5,11,17,18, and 20 and the control C, which exhibited a simple banding pattern, were used in further analyses. We used the disruptant strain ΔClm2D20 to generate 23 add-back strains in which the entire Clm2 gene plus ∼1 kb upstream and 550 bp downstream of the gene were inserted into the genome (confirmed by PCR and Southern analysis; data not shown).…”