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A liquid culture method for the production of deoxynivalenol and related compounds by Fusarium graminearum was developed. Major factors which stimulate the biosynthesis of these compounds include reduced oxygen levels, depletion of carbohydrate in the medium, pH, and possibly a low concentration of an organic nitrogen source. Isolates of F. graminearum were tested for the yields of four trichothecene mycotoxins and zearalenone in this system. The time course of acetyl deoxynivalenol, deoxynivalenol, and zearalenone in the fermentation was measured over a 21-day period against pH, glucose concentration, protein, fungal biomass, and ergosterol. A new ester of deoxynivalenol, 15-acetyl-deoxynivalenol, is reported from North American isolates of F. graminearum.

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The ultraviolet irradiation of fenitrothion in oxygenated solutions produced isomerization, oxidation, and solvolysis. In hexane, both the P=S and the aryl methyl group were oxidized to give fenitrooxon and formylfenitrothion. Small amounts of denitrofenitrothion were also formed. Irradiation in methanol gave carbomethoxyfenitrothion formed from oxidation followed by solvolysis. Isomerization of fenitrothion to its S-methyl isomer took place on a small scale in all solvents; however, no S-aryl isomer was detected. Irradiation of hydroxymethylfenitrothion in hexane readily gave formyl-and carboxyfenitrothion. This supports the suggestion that hydroxymethylfenitrothion is a reactive intermediate formed in the photolysis of fenitrothion. Several potential oxidation products, hydroxymethyl, formyl, carboxy, and carbomethoxy analogues of fenitrothion and fenitrooxon were prepared together with the S-aryl isomer. The mass spectral (MS) and nuclear magnetic resonance (NMR) data, gas chromatographic (GC), and thin-layer chromatographic (TLC) properties of these compounds and other fenitrothion derivatives are given.Fenitrothion [O,O-dimethyl 0-(4-nitro-m-tolyl) phosphorothioate] (I) is an important insecticide used in many countries for orchard and field crops. In Canada, its main use is to control defoliators in forests.It is structurally similar to parathion, the ultraviolet (uv) photolysis of which has been extensively studied (Cook and Pugh, 1957; Frawley et al., 1958;Koivistoinen and Merilainen, 1963;El-Rafai and Hopkins, 1966; and Joiner and Baetcke, 1974). In contrast, little work has been carried out on the photolysis of fenitrothion. Brewer et al. (1974) reported the formation of two products on irradiation of fenitrothion with light >300 nm, one of which was identified as 4-nitro-rn-cresol (11). A more exhaustive investigation was carried out by Ohkawa et al. (1974) who studied the photodecomposition in various solvents and as films by both uv and sunlight. Five products were isolated, resulting from photoinduced isomerization, oxidation, hydrolysis, and solvolysis. The predominant reaction in benzene, acetone, methanol, and aqueous methanol was oxidation of the aryl methyl group to give carboxyfenitrothion and its oxygen analogue, which were characterized by nuclear magnetic resonance (NMR) and infrared (ir) spectroscopy.