Aspergillus flavus from coffee in Cameroon: a non-aflatoxigenic endophytic isolate antagonistic to coffee leaf rust (Hemileia vastatrix).

AIMS: Elucidating the identity of an isolate of Aspergillus sp. obtained during searches for anti-coffee leaf rust (CLR) biocontrol agents, from healthy coffee berry samples, preliminarily verify whether it is an aflatoxin-producer, confirm its ability to grow as an endophyte in healthy coffee tissues and assess its biocontrol potential against CLR. METHODS AND RESULTS: One, among hundreds of fungal isolates fungus were obtained from healthy coffee tissues belonged to Aspergillus (isolate COAD 3307). A combination of morphology features and molecular analyses; including four regions-internal transcribed spacer, second-largest subunit of RNA polymerase (RPB2), ß-tubulin (BenA) and calmodulin (CAL)-identified COAD 3307 as Aspergillus flavus. Inoculations of healthy Coffea arabica with COAD 3307 confirmed its establishment as an endophyte in leaves, stems, and roots. Treatment of C. arabica plants by combinated applications of COAD 3307 on aerial parts and in the soil, significantly (P > .0001) reduced CLR severity as compared to controls. Thin-layer chromatography indicated that COAD 3307 is not an aflatoxin-producing isolate. In order to confirm this result, the extract was injected into high-performance liquid chromatography system equipped with a fluorescence detector, and no evidence of aflatoxin was found. CONCLUSIONS: COAD 3307 is an endophytic isolate of A. flavus-a species that has never been previously recorded as an endophyte of Coffea spp. It is a non-aflatoxin producing strain that has an anti-CLR effect and merits further evaluation as a biocontrol agent.

Effect of temperature on growth, gene expression, and aflatoxin production by Aspergillus nomius isolated from Brazil nuts.

Aspergillus nomius is a potent producer of aflatoxins B and G and is one of the most common species of fungi found in Brazil nuts. Temperature is considered a major abiotic factor that influences fungal colonization and aflatoxin production in nuts during pre- and post-harvest. Therefore, assessment of the response of aflatoxigenic species to different temperatures is important to add information about the understanding of aflatoxin production by Aspergillus nomius and may help in the development of new strategies to prevent aflatoxin contamination. The aim of this study was to evaluate the effect of temperature (25, 30, and 35 °C) on the radial growth, aflatoxin production (B and G), and aflatoxin gene expression of seven A. nomius strains isolated from Brazil nuts. The optimal temperature for growth was 30 °C and was also the best condition for the expression of the aflR, aflD, and aflQ genes. However, maximum production of aflatoxins B and G occurred at 25 °C. Interestingly, high expression of the structural gene aflQ was observed in the maximum aflatoxin production condition (25 °C). The present study demonstrates that temperature may influence aflatoxin production by A. nomius. The combination of molecular and physiological data aids the understanding of the aflatoxigenic species response to different temperatures and can assist in predicting the driving environmental factors that influence aflatoxin contamination of Brazil nuts.

Fusarium verticillioides and fumonisin contamination in Bt and non-Bt maize cultivated in Brazil.

Fusarium verticillioides is one of the main pathogens of maize, causing ear and stalk rots. This fungus is also able to produce high levels of fumonisins, which have been linked to various illnesses in humans and animals. Previous studies have shown that maize hybrids genetically modified with the cry genes from the bacterium Bacillus thuringiensis (Bt) presented lower incidence of F. verticillioides and fumonisin levels, presumably through the reduction of insects, which could act as vectors of fungi. The aim of this study was to assess the incidence of F. verticillioides and the concentration of fumonisins in Bt and isogenic non-Bt hybrids (2B710Hx, 30F35YG, 2B710, and 30F35, respectively). The samples of 2B710Hx and 30F35YG presented lower F. verticillioides frequency than 2B710 and 30F35 samples. However, there was no statistical difference between fumonisin contamination when Bt and non-Bt samples were compared (P > 0.05). The results suggest that other environmental parameters could possibly trigger fumonisin production during plant development in the field; consequently, other management strategies should be applied to aid controlling fumonisin contamination in maize.

Mycotoxin analysis of industrial beers from Brazil: The influence of fumonisin B1 and deoxynivalenol in beer quality.

Worldwide, barley is the main source of carbohydrate in the brewing process. However, corn is often used as an adjunct to improve and accelerate the fermentation process. Considering that, these two substrates are susceptible to fungal contamination as well as mycotoxins. The objective of the current study is to determine the incidence of the mycotoxins deoxynivalenol (DON) and fumonisin B1 (FB1) in industrial beers. The method applied for mycotoxin analyses included high performance liquid chromatography. The mean levels for recovery experiments were 89.6% for DON and 93.3% for FB1. DON was not detected in any of the analyzed samples whereas FB1 was found in 49% of the 114 samples. The current survey demonstrated levels of FB1 contamination in industrial beer, possibly due to the addition of contaminated adjuncts. It is necessary to establish maximum levels of mycotoxins in beer in Brazil and other countries in order to reduce health risks.

Alternative fat substitutes for beef burger: technological and sensory characteristics.

This study aimed to develop a type of hamburger meat product and evaluate the physical features and sensory formulations of oatmeal flour, flour of green banana pulp, flour of green banana peel, flour of apple peel and pulp of Green Banana as fat substitutes. Regarding color, the formulations containing fat substitutes based on green banana presented lower values for b* and L*. Hamburgers with added oatmeal and apple peel flour obtained high values of a* and low values of L*, producing the reddest burgers. Substitutes based on green banana differed from others, resulting in a higher yield of burgers and water-holding capacity during cooking, besides having lower toughness and less shrinkage. The sensory acceptance test for untrained consumers suggests that the flour of peel and pulp of green banana, and oatmeal flour are excellent choices for fat-substitution in beef burger. Although fat contributes to a series of physical and sensory attributes such as softness, juiciness and yield, it is possible to reduce the lipid content in beef burgers without depreciating the quality of food through the use of the following fat substitutes: oat flour, apple peel flour, green banana pulp flour, green banana peel flour and green banana pulp.

Monitoring and determination of fungi and mycotoxins in stored Brazil nuts.

Brazil nut (Bertholletia excelsa) is an important commodity from the Brazilian Amazon, and approximately 37,000 tons (3.36 × 107 kg) of Brazil nuts are harvested each year. However, substantial nut contamination by Aspergillus section Flavi occurs, with subsequent production of mycotoxins. In this context, the objective of the present investigation was to evaluate the presence of fungi and mycotoxins (aflatoxins and cyclopiazonic acid) in 110 stored samples of cultivated Brazil nut (55 samples of nuts and 55 samples of shells) collected monthly for 11 months in Itacoatiara, State of Amazonas, Brazil. The samples were inoculated in duplicate onto Aspergillus flavus and Aspergillus parasiticus agar and potato dextrose agar for the detection of fungi, and the presence of mycotoxins was determined by high-performance liquid chromatography. The most prevalent fungi in nuts and shells were Aspergillus spp., Fusarium spp., and Penicillium spp. A polyphasic approach was used for identification of Aspergillus species. Aflatoxins and cyclopiazonic acid were not detected in any of the samples analyzed. The low water activity of the substrate was a determinant factor for the presence of fungi and the absence of aflatoxin in Brazil nut samples. The high frequency of isolation of aflatoxigenic Aspergillus section Flavi strains, mainly A. flavus, and their persistence during storage increase the chances of aflatoxin production on these substrates and indicates the need for good management practices to prevent mycotoxin contamination in Brazil nuts.

Fungi, mycotoxins and phytoalexin in peanut varieties, during plant growth in the field.

The aim of the present study was to analyze the mycobiota, occurrence of mycotoxins (aflatoxins and cyclopiazonic acid), and production of phytoalexin (trans-resveratrol) in two peanut varieties (Runner IAC 886 and Caiapó) during plant growth in the field. Climatic factors (rainfall, relative humidity and temperature) and water activity were also evaluated. The results showed a predominance of Fusarium spp. in kernels and pods, followed by Penicillium spp. and Aspergillus flavus. Aflatoxins were detected in 20% and 10% of samples of the IAC 886 and Caiapó varieties, respectively. Analysis showed that 65% of kernel samples of the IAC 886 variety and 25% of the Caiapó variety were contaminated with cyclopiazonic acid. trans-Resveratrol was detected in 6.7% of kernel samples of the IAC 886 variety and in 20% of the Caiapó variety. However, trans-resveratrol was found in 73.3% of leaf samples in the two varieties studied.

Mycoflora and co-occurrence of fumonisins and aflatoxins in freshly harvested corn in different regions of Brazil.

Natural mycoflora and co-occurrence of fumonisins (FB(1), FB(2)) and aflatoxins (AFB(1), AFB(2), AFG(1) and AFG(2)) in freshly harvested corn grain samples from four regions of Brazil were investigated. Fusarium verticillioides was predominant in all samples. Analysis of fumonisins showed that 98% of the samples were contaminated with FB(1) and 74.5% with FB(1) + FB(2), with toxin levels ranging from 0.015 to 9.67 microg/g for FB(1) and from 0.015 to 3.16 microg/g for FB(2). Twenty-one (10.5%) samples were contaminated with AFB(1), seven (3.5%) with AFB(2) and only one (0.5%) with AFG(1) and AFG(2) Co-contamination with aflatoxins and fumonisins was observed in 7% of the samples. The highest contamination of fumonisins and aflatoxins was observed in Nova Odessa (SP) and Várzea Grande (MT), respectively. The lowest contamination of these mycotoxins was found in Várzea Grande and Nova Odessa, respectively.

Influência de nutrientes no crescimento fúngico e na produção de fumonisinas e aflatoxinas em grão de milho / The nutrients effect on mycoflora, and for fumonisins and aflatoxins production in corn grain

O presente experimento teve como objetivo correlacionar os resultados obtidos da microbiota fúngica e produção de micotoxinas com os níveis de nitrogênio, zinco e boro utilizados no plantio do milho. Foram realizados tratamentos com quatro concentrações de nitrogênio (0, 50, 100 e 150 kg/ha) de forma interativa com duas concentrações de zinco (0,5 e 1,0 kg/ha), duas concentrações de boro (0,25 e 0,5 kg/ha) e duas concentrações de zinco mais boro (0,5 e 1,0; 0,25 e 0,5 kg/ha respectivamente), perfazendo um total de 25 tratamentos. A média de contaminação das amostras de milho pelos gêneros Aspergillus, Penicillium e Fusarium foi de 42,7; 38,9 e 41,5% respectivamente, principalmente na faixa de 0,53 a0,63 de atividade de água. A análise de fumonisinas revelou uma contaminação em 100% das amostras,em níveis que variaram de 1,7 a 27,9 mg/kg para FB1 e de 0,3 a 11,2 mg/kg para FB2. Foi detectada aflatoxina B1 em 7 amostras de milho (16,0 a 1858,3 g/kg) e B2 em 3 amostras (14,6 a 110,3 g/kg). A análise de Variância demonstrou que o nitrogênio foi positivamente significativo (p<0,05) sobre a porcentagem de contaminação pelo gênero Fusarium, enquanto que para o gênero Aspergillus foi negativamente significativo (p<0,10).