Interacting environmental factors, growth and temporal deoxynivalenol production by strains of Fusarium graminearum from Argentina on wheat grain

RAMIREZ M.L.; CHULZE S.N.; MAGAN N

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

Elsevier

Lugar: Amsterdam; Año: 2006 vol. 106 p. 291 - 296

0168-1605

The objective of this study was to determine the effects of water activity (aW; 0.900–0.995), temperature (5, 15, 25 and 30 -C), time ofincubation (7–49 days) and their interactions on mycelial growth and deoxynivalenol (DON) production on irradiated wheat grain by two strainsof Fusarium graminearum isolated from wheat ears in Argentina. Optimal aW levels for growth were in the range 0.950–0.995 with a temperatureoptima of 25 -C. Maximum growth rates were obtained at the highest aW (0.995) and 25 -C for both strains. No growth was observed at 5 -Cregardless of the aW levels assayed. Both strains were able to growth at the lowest aW assayed (0.900), although the temperature ranges allowinggrowth at this minimal aW was 15–25 -C. DON was produced the most rapidly (7 days) when incubated at 25 -C and 0.995 aW. All otherconditions required 7–14 days before DON was produced on grain. Maximum amounts of DON for both strains were produced at the highest aWtreatment (0.995) after 6 weeks at 30 -C. The range of DON concentrations varied considerably (5 to 140,000 ng g1) depending on aW andtemperature interaction treatments. Production of DON occurred over a narrower range of aW (0.995–0.95) than that for growth (0.995–0.90).DON was more rapidly produced at 25 -C but the maximum amount produced was at 30 -C. Two-dimensional profiles of aWtemperature weredeveloped from these data to identify areas where conditions indicate a significant risk from DON accumulation.aW; 0.900–0.995), temperature (5, 15, 25 and 30 -C), time ofincubation (7–49 days) and their interactions on mycelial growth and deoxynivalenol (DON) production on irradiated wheat grain by two strainsof Fusarium graminearum isolated from wheat ears in Argentina. Optimal aW levels for growth were in the range 0.950–0.995 with a temperatureoptima of 25 -C. Maximum growth rates were obtained at the highest aW (0.995) and 25 -C for both strains. No growth was observed at 5 -Cregardless of the aW levels assayed. Both strains were able to growth at the lowest aW assayed (0.900), although the temperature ranges allowinggrowth at this minimal aW was 15–25 -C. DON was produced the most rapidly (7 days) when incubated at 25 -C and 0.995 aW. All otherconditions required 7–14 days before DON was produced on grain. Maximum amounts of DON for both strains were produced at the highest aWtreatment (0.995) after 6 weeks at 30 -C. The range of DON concentrations varied considerably (5 to 140,000 ng g1) depending on aW andtemperature interaction treatments. Production of DON occurred over a narrower range of aW (0.995–0.95) than that for growth (0.995–0.90).DON was more rapidly produced at 25 -C but the maximum amount produced was at 30 -C. Two-dimensional profiles of aWtemperature weredeveloped from these data to identify areas where conditions indicate a significant risk from DON accumulation. D 2005 Elsevier B.V. All rights reserved.2005 Elsevier B.V. All rights reserved.