The presence of ochratoxin A (OTA) is evaluated using thin layer chromatography (TLC) with a charge-coupled detector (CCD) in 88 red wine samples (2009 vintage) from Brazil. Samples included 75 wines from Rio Grande do Sul, nine from Santa Catarina and four from Paraná state; 56 wines were Cabernet Sauvignon and 32 were Merlot varieties. The method included the analysis of fluorescent images, acquired under UV light, using ImageJ software. Mean recovery of OTA was 82.3% using immunoaffinity columns (IAC). The limits of quantification (LOQ) and detection (LOD) were 0.8 and 0.2 µg l(-1), respectively. Results showed a 5.7% contamination of OTA, with five positive samples--three Cabernet Sauvignon and two Merlot. Santa Catarina and Paraná showed one positive sample each, although the concentrations were below the limit of quantification. The highest concentration found was 0.84 µg l(-1) in one sample from Rio Grande do Sul.
Aspergillus westerdijkiae is one of the most important spoilage and toxigenic fungi contaminating coffee beans and may produce ochratoxin A (DTA), a mycotoxin that characterize a health risk to the coffee consumers. Biological control strategies can be used for prevention of fungal invasion and decrease mycotoxin exposure. The aims of this study were to evaluate the in vitro effect of three Bacillus sp. biocontrol candidates on A. westerdijkiae mycelial growth, spore counts and DTA production. A green-coffee based medium was inoculated with A. westerdijkiae and Bacillus spp. (B. safensis RF69, B. amyloliquefaciens RP103 and B. subtilis RP242) and after incubation, the fungal growth, sporulation and mycotoxin production was evaluated. Mycelial growth rate was reduced in a range between 76-95% and conidial production was also significantly decreased. All isolates were capable of reducing DTA production in a range between 62-96%. The results showed that the biocontrol candidates may be an effective control method for A. westerdijkiae and DTA in coffee.Keywords: biological control; food mycology; mycotoxins; fungi; food safety.
Practical Application:Intense inhibition of A. westerdijkie by Bacillus spp. in a coffee-based medium.
ResumoFusarium graminearum is a potential producer of several mycotoxins, as trichothecenes, causing economic and nutritional losses and risks to human and animal health. Researches about antagonistic potential microorganisms have increasead in order to control of fungal growth and mycotoxin synthesis. Bacillus strains isolated from aquatic environment of Brazilian Amazon basin have shown antifungal activity against filamentous fungi. There is no specific report on the impact of these isolates on growth of toxigenic F. graminearum. The aim of this work was to screen Bacillus strains isolated from aquatic environments of Brazilian Amazon region for their antifungal activity against mycelial growth of F. graminearum. Both Bacillus strains and F. graminearum were obtained from the collection center at Laboratory of Applied Biochemistry and Microbiology (ICTA/ UFRGS, Brazil). For antifungal activity, bacteria were cultured in tryptone soy broth (TSB) for 48 h at 37°C. Sterile molten potato dextrose agar (PDA) containing spore suspension was transferred to Petri dishes. After solidification, each isolate was inoculated on PDA plates. The inhibition zones were measured after 7 days of incubation at 25 °C. To evaluate the effect on radial growth, Bacillus strains inocula were added on PDA, and a spore suspension was placed in the centre of each plates and incubated at 25 °C for 10 days. The growing radius of the fungal colonies was measured 467
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