Production of fumonisins by Fusarium verticillioides strains on solid and in a defined liquid medium--effects of L-methionine and inoculum.
In order to evaluate the toxicological and carcinogenic effects of fumonisins, large amounts of fumonisins need to be purified, which requires optimal conditions for production in culture. Five strains of F. verticillioides were compared for their ability to produce fumonisins in solid and liquid media with and without the addition of methionine, a fumonisin precursor. Inoculations were made either with lyophilized cultures or a concentrated inoculum. Growth in liquid medium, measured by biomass, was directly correlated to total fumonisin production when a lyophilized inoculum was used. Fumonisin production was stimulated by the addition of 0.2% L-methionine to solid media for most strains. Levels ranged from 1500-3900 mg/kg in rice, and 2900-12500 mg/kg in maize cultures inoculated with lyophilized cultures; 200-4800 mg/kg in rice, and 1500-4200 mg/kg in maize cultures inoculated with concentrated inoculum. Strains that produced relatively high levels of fumonisins in solid media did not necessarily do so in liquid medium and vice versa. Total fumonisin levels in liquid medium ranged from 40-590 mg/l inoculated with lyophilized cultures and < 1-110 mg/l inoculated with concentrated inoculum, without adding the precursor. F. verticillioides strains therefore varied in their ability to produce fumonisins, and conditions for production need to be optimized individually for each strain.
Medical Research Council, PROMEC Unit, P.O. Box 19070, Tygerberg, 7505 South Africa. hester.vismer@mrc.ac.za
Hester Francis
HF
Vismer
Petra Wilhelmina
PW
Snijman
Walter Friedrich Otto
WF
Marasas
Dirk Jacobus
DJ
van Schalkwyk
D018533:Biomass; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media / Q000378:metabolism; D037341:Fumonisins / Q000378:metabolism*; D005670:Fusarium / Q000254:growth & development / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism* / Q000494:pharmacology; D009183:Mycotoxins / Q000096:biosynthesis*; D012275:Oryza / Q000382:microbiology; D003313:Zea mays / Q000382:microbiology
D003470:Culture Media; D037341:Fumonisins; D009183:Mycotoxins; C056933:fumonisin B1; D008715:Methionine