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This study examined the effect of interacting conditions of water activity (a W , 0.995, 0.98 and 0.95) and temperature (15, 25 and 30 °C) on growth rate of two Fusarium thapsinum and one F. andiyazi strains isolated from sorghum in Argentina. In addition, the effect of interacting conditions (a W × temperature × incubation time (7, 14, 21 and 28 days)) on mycotoxin production (moniliformin (MON), fusaric acid (FA) and fusarin C (FUS C)) on a sorghum grain substrate was evaluated. Statistical analysis showed that a W and temperature significantly affected growth of both species, mainly the a W. Incubation time significantly influenced mycotoxin production by both species as well, mostly for FA. Maximum growth rates of the F. thapsinum strains were obtained at the highest a W (0.995) and 25 °C and growth rate decreased as a W and temperature were reduced. The same growth profile was observed for F. andiyazi RCFA09 (maximum growth rates at 0.995–25 °C). Mycotoxin production by both species was detected at the highest a W levels whereas at 0.95 a W only low amounts of MON were produced by F. thapsinum. Maximum MON and FUS C production by both F. thapsinum strains was observed at 0.995 a W and 25–30 °C after 28 days of incubation. Also, F. thapsinum strains showed maximum FA production at the highest a W and temperature but after 14 days; after this incubation time toxin levels significantly decreased. The responses to a W and temperature of F. andiyazi were similar to that of F. thapsinum strains in relation to FA and FUS C production. Maximum levels of FA were detected at the highest a W after 14 days of incubation at 25–30 °C. Fusarin C was produced at all assayed temperatures but maximum levels were detected at 30 °C and 0.995 a W after 28 days of incubation. Two-dimensional profiles on the interactions of a W by temperature were developed from these data to identify conditions that indicate a significant risk from MON, FA and FUS C accumulation on sorghum grains. The results of this study suggest that sorghum grains could be colonized by these species and toxin production can occur, especially during development stages under field conditions at high water activity of grains or during grain storage if the drying process is slow or deficient. To our knowledge, this study described for the first time FUS C production by F. thapsinum and F. andiyazi under interacting conditions of a W , temperature and incubation time on sorghum grains. • Growth of Fusarium thapsinum and F. andiyazi was significantly influenced by a w. • Maximum MON levels were detected at 30 °C and 0.995 a W after 28 days. • FA production by both species was maximum at 14 days of incubation instead of 28. • This is the first report on fusarin C production by F. thapsinum and F. andiyazi. [ABSTRACT FROM AUTHOR]

The Chaco wetland is among the most biologically diverse regions in Argentina. In collections of fungi from asymptomatic native grasses (Poaceae) from the wetlands, we identified isolates of Fusarium that were morphologically similar to F. armeniacum , but distinct from it by their production of abundant microconidia. All the isolates had identical, or nearly identical, partial sequences of TEF1 and RPB2 . But they were distinct from reference sequences from F. armeniacum and Fusarium species closely related to it. Phylogenetic analysis of 34 full-length housekeeping gene sequences retrieved from whole genome sequences of three Chaco wetland isolates, 29 genes resolved the isolates as an exclusive clade within the F. sambucinum species complex. Based on results of the morphological and phylogenetic analysis, we concluded that the Chaco wetland isolates are a distinct and novel species, herein described as Fusarium chaquense , sp. nov., which is closely related to F. armeniacum. F. chaquense in culture can produce the trichothecenes T-2 and HT-2 toxin, neosolaniol, diacetoxyscirpenol, and monoacetoxyscirpenol, as well as beauvericin and the pigment aurofusarin. Genome sequence analysis also revealed the presence of three previously described loci required for trichothecene biosynthesis. This research represents the first study of Fusarium in a natural ecosystem in Argentina.

In Argentina, wheat is the most consumed cereal by the human population. Since fumonisins occurence in wheat grains and wheat-based products have been reported worldwide, a survey was conducted in order to determine fumonisin contamination in 91 wheat-based products (white wheat flour samples, wheat flour used at bakery products and whole-wheat flour samples) collected from different retail stores of Rio Cuarto city in Argentina using HPLC-MS/MS. Sixty-seven samples (74%) showed contamination by fumonisins. From these samples, 16 showed fumonisin levels between LOD and LOQ (between 0.01 to 0.05 ng/g), while fumonisins (FB 1 + FB 2 ) in quantifiable samples ranged from 0.05 ng/g to 18.9 ng/g. Although FB 1 was more prevalent, FB 2 was foun3d in higher levels than FB 1 . Overall, fumonisin prevalence was high, but concentrations were far below EU or USA limits set for maize and maize-based products.

The aim of this study was to evaluate the occurrence of several fungal metabolites, including mycotoxins in natural grasses (Poaceae) intended for grazing cattle. A total number of 72 and 77 different metabolites were detected on 106 and 69 grass samples collected during 2011 and 2014, respectively. A total of 60 metabolites were found across both years. Among the few mycotoxins considered toxic for ruminants, no samples of natural grasses were contaminated with aflatoxins, ochratoxin A, ergot alkaloids, and gliotoxin, among others. However, we were able to detect important metabolites (toxic to ruminants) such as type A trichothecenes, mainly T-2 toxin and HT-2 toxin (up to 5000 µg/kg each), and zearalenone (up to 2000 µg/kg), all at very high frequencies and levels. Other fungal metabolites that were found to be prevalent were other Fusarium metabolites like beauvericin, equisetin and aurofusarin, metabolites produced by Alternaria spp., sterigmatocystin and its precursors and anthrachinone derivatives. It is important to point out that the profile of common metabolites was shared during both years of sampling, and also that the occurrence of important metabolites is not a sporadic event. Considering that this area of temperate grassland is used for grazing cattle all year long due to the richness in palatable grasses (Poaceae), the present work represents a starting point for further studies on the occurrence of multi-mycotoxins in natural grasses in order to have a complete picture of the extent of cattle exposure. Also, the present study shows that the presence of zeranol in urine of beef cattle may not be a consequence of illegal use of this banned substance, but the product of the natural occurrence of zearalenone and α-zearalenol in natural grasses intended for cattle feeding.