Fusarium species and moniliformin occurrence in sorghum grains used as ingredient for animal feed in Argentina

Abstract

BACKGROUND: A survey on Fusarium species and moniliformin (MON) occurrence in sorghum grains collected from one of the main sorghum-producing areas of Argentina was conducted. Also, growth of F. thapsinum, one of the main sorghum pathogens, and MON production under different water activity (aw) conditions on a sorghum-based medium were determined. RESULTS: Infection of sorghum grains by Fusarium species ranged from 82.5 to 99%; closely related species F. verticillioides, F. thapsinum and F. andiyazi were the most frequently recovered, followed by F. proliferatum and F. subglutinans. By sequencing a portion of the translation elongation factor-1α (TEF-1α) gene and by maximum parsimony analysis, F. verticillioides and closely related species were identified as F. thapsinum, F. andiyazi and F. verticillioides. Species within the F. graminearum species complex (FGSC) were isolated in high frequency. Maximum growth rates of 12 F. thapsinum strains were obtained at 0.995 aw. All evaluated strains were able to produce MON at all aw values tested, but MON production was higher at 0.995–0.982 aw. MON was detected in 41% of the samples at levels ranging from 363.2 to 914.2 µg kg−1. CONCLUSION: This study provides new data on the occurrence of Fusarium species in sorghum grains destined for animal consumption in Argentina. The production of MON at different aw values showed that the toxin can be produced under field conditions. The risk to livestock exposed to daily low levels of MON associated with the toxin occurrence in the sorghum grains analyzed is unknown.