Environmental factors modify carbon nutritional patterns and niche overlap between Aspergillus flavus and Fusarium verticillioides strains from maize.

This study examined the utilization patterns of key carbon sources (CS, 24: including key sugars, amino acids and fatty acids) in maize by strains of Aspergillus flavus and Fusarium verticillioides under different water activity (aw, 0.87–0.98 aw) and temperature (20–35 °C) values and compared the niche overlap indices (NOI) that estimate the in vitro CS utilization profiles [Wilson, M., Lindow, S.E., 1994. Coexistence among epiphytic bacterial populations mediated through nutritional resource partitioning. Applied and Environmental Microbiology 60, 4468–4477.]. The ability to grow in these key CS in minimal media was studied for 120 h in 12 h steps. The NOI was calculated for inter-species (F. verticillioides–A. flavus) and for intra-species (A. flavus–A. flavus) using CS utilization patterns over the range of interacting environmental conditions. 30 °C, over the whole aw range examined, was found to be optimal for utilization of the maximum number of CS by A. flavus. In contrast, for F. verticillioides this was more so at 20 °C; 25 °C allowed a suboptimal usage of CS for both species. NOIs confirmed the nutritional dominance of A. flavus at 30 °C, especially at lower aw levels and that of F. verticillioides at 20 °C, mainly at 0.95 aw. In other conditions of aw, based on CS utilization patterns, the data indicated that A. flavus and F. verticillioides occupied different ecological niches. The variability in nutritional sources utilization between A. flavus strains was not related to their ability to produce aflatoxins (AFs). This type of data helps to explain the nutritional dominance of fungal species and strains under different environmental conditions. This could be useful in trying to find appropriate natural biocontrol microorganisms to compete with these mycotoxigenic species

Foreword: mycotoxins in a changing world

This special issue arose because of the changes in the global landscape in relation to the impact and implications of our changing climate on food security and quality, consumer habits, trade and economics, regulations and scientific thinking. The EU green paper (EC, 2007) on climate change (CC) has suggested significant hot spots in different regions where food production will be considerably affected both in quality and quantity. Indeed, a recent UNEP report on ‘Emerging Issues of Environmental Concern’ (UNEP, 2016) has included a section entitled ‘Poisoned chalice: Toxin accumulation in crops in an era of climate change’ which refers to the impact that aflatoxin contamination is having in low and middle income countries (LMICs)

Chemical and biological control of Fusarium species involved in garlic dry rot at early crop stages

AbstractThe aim of the study was to test in vitro and in vivo the efficacy of triazoles and biocontrol agents (BCAs) against Fusarium proliferatum and F. oxysporum, the former signaled as the main causal agent of garlic dry rot and the latter also involved. In vitro trials were organized using potato dextrose agar with added chemicals or BCAs inoculated with selected F. proliferatum and F. oxysporum. Garlic cloves were dipped before sowing in suspensions prepared with the fungicides showing the best performances in vitro; then they were dipped in Fusaria suspension before sowing. In in vitro trials, the maximum Fusaria growth inhibition was performed by Propiconazole + Prochloraz (100%), followed by Tebuconazole (88.9%). BCAs showed great capacity to control Fusaria, with a maximum growth inhibition of 80% (Trichoderma harzianum + T. gamsii). In vivo bacterial BCAs showed a similar capacity to control F. proliferatum and F. oxysporum compared to chemical products (mean of severity index 18.6% and 11.7%, respectively). In vivo results confirmed the in vitro performances, except for Trichoderma, which had the worst performances in vivo. Therefore, the results are preliminary but promising for future field application

Open field study of some Zea mays hybrids, lipid compounds and fumonisins accumulation

Lipid molecules are increasingly recognized as signals exchanged by organisms interacting in pathogenic and/or symbiotic ways. Some classes of lipids actively determine the fate of the interactions. Host cuticle/cell wall/membrane components such as sphingolipids and oxylipins may contribute to determining the fate of host–pathogen interactions. In the present field study, we considered the relationship between specific sphingolipids and oxylipins of different hybrids of Zea mays and fumonisin by F. verticillioides, sampling ears at different growth stages from early dough to fully ripe. The amount of total and free fumonisin differed significantly between hybrids and increased significantly with maize ripening. Oxylipins and phytoceramides changed significantly within the hybrids and decreased with kernel maturation, starting from physiological maturity. Although the correlation between fumonisin accumulation and plant lipid profile is certain, the data collected so far cannot define a cause-effect relationship but open up new perspectives. Therefore, the question—“Does fumonisin alter plant lipidome or does plant lipidome modulate fumonisin accumulation?”—is still open

Impact of environmental and plant factors on Aspergillus section Flavi isolated from maize in Italy

The exceptional hot weather conditions in Italy during the summer of 2003 resulted in an optimal environment for the development of Aspergillus section Flavi in maize and, consequently, for aflatoxin production. This caused significant contamination, above the EU legal limits, for maize destined to feed and food. This study was focused to define the distribution of these fungi in Italy for the first time. In all the sampled regions of Northern Italy, A. flavus was present. Ecological studies were conducted and this defined the cardinal conditions of water availability (0.83-0.99 aw), temperature (15-45°C) and gas composition (CO2<50%) for sporulation, growth and aflatoxin B1 production. Since in the field A. flavus does not occur alone, possible interactions with the fumonisin producing species Fusarium verticillioides was examined by using carbon source utilisation patterns and niche overlap indices. F. verticillioides was a better competitor over the range 0.93-0.98 aw and temperature of 20°C while A. flavus dominated at 0.98 aw and 30°C. Inoculum concentration (10 1 -10 7 CFUs ml) affected infection efficiency, with a low percentage of kernels becoming infected with up to 10 5 conidia mL -1 , and early maize growth stages were more susceptible. A total of 34 maize hybrids were screened for resistance to A. flavus and aflatoxin production and this showed that about 40% of these showed promise. The data sets obtained in this study wil provide a powerful basis for the development of a Decision Support System to minimize aflatoxins in maize.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Occurrence of ochratoxin A-producing fungi in grapes grown in Italy

A study was carried out to investigate fungi present on grapes grown in Italy. Aspergillus and Penicillium spp. isolates were identified and studied in vitro, and their ability to produce ochratoxin A (OA) was investigated. The survey involved nine vineyards, three located in northern Italy and six located in southern Italy. In 1999 and 2000, bunches of grapes at different growth stages were collected from all nine vineyards, and berry samples were placed in moist chambers and incubated. The resultant fungal colonies were then transferred to petri dishes containing Czapek yeast agar and incubated at 25 degrees C for 7 days; the fungal isolates were identified and then cultivated in liquid Czapek yeast medium and evaluated for their ability to produce OA. During the survey, 508 isolates were collected, with 477 belonging to Aspergillus spp. and 31 belonging to Penicillium spp. Among the aspergilli, species of the Fumigati, Circumdati, and Nigri sections were identified, with species of the Nigri section (464 isolates) largely predominating; for species of the Nigri section, 108 isolates were uniseriate, 270 were biseriate, and 86 were identified as Aspergillus carbonarius. Black aspergilli isolated over the 2 years of the study showed a very similar pattern. On average, the biseriates represented about 60% of the isolates collected in both years and were followed by uniseriates (21%) and A. carbonarius (19%). The most toxigenic strains proved to be those of A. carbonarius; about 60% of these isolates were OA producers and produced the highest levels of OA. A. carbonarius was more frequent in the south, but in both areas the percentages of OA-producing isolates remained the same

Caracterização de linhagens de Aspergillus e Penicillium isoladas da superfície de queijo curado italiano do tipo “grana”

O queijo curado Italiano do tipo “grana” é um produto de alto valor comercial. Apesar de se observar o crescimento de linhagens pertencentes aos géneros Aspergillus e Penicillium, que têm espécies potencialmente produtoras de micotoxinas, não existe muita informação acerca da micobiota associada a este produto. As micotoxinas, produzidos por algumas espécies fúngicas, podem ter efeitos nocivos graves na saúde humana e animal. Assim, é essencial estudar o micobiota deste queijo, de modo a se poder fazer uma análise do risco associado às espécies envolvidas. A ocorrência de micotoxinas no queijo tem vindo a ser gradualmente reportada, como a ocratoxina A (OTA) e a esterigmatocistina (STC). Apesar destas micotoxinas estarem incluídas no grupo 2B pela IARC/International Agency for Research on Cancer, i.e., serem potencialmente cancerígenas para os humanos, neste momento, não existe legislação Europeia que as regule no queijo. O objectivo deste trabalho foi obter pela primeira um levantamento sobre linhagens de Penicillium e Aspergillus que crescem na superfície do queijo curado Italiano do tipo “grana”, dando especial atenção às espécies micotoxigénicas. Para o efeito, entre os anos de 2013 e 2014, foram obtidas amostras raspadas da crosta do aro da cura e foram expostas ao ar placas com meio de batata e dextrose agarizado para monitoramento das câmaras de cura. Dos fungos isolados foram escolhidos aleatoriamente 140 linhagens de colónias monoespóricas (89% Penicillium e 11% Aspergillus) para a identificação ao nível de espécie usando a abordagem polifásica com a caracterização morfológica, perfil de extrólitos e molecular. As espécies mais representativas foram: Penicillium solitum (54), P. crustosum (20), P. commune (12), P. nordicum (11), Aspergillus puulaaeunsis (6), A. flavus (5), P. charlesii (3), P. chrysogenum (3), P. paneum (3), P. citrinum (2), P. jugoslavicum (2). Em conclusão, este trabalho permitiu fazer pela primeira vez um levantamento das espécies contaminantes deste tipo de queijo bem como verificar a presença de linhagens produtoras de aflatoxinas (A. flavus), de STC (A. puulaaeunsis) e de OTA (P. nordicum). Mediante estes resultados, pode-se inferir que o risco de ocorrência de micotoxinas neste produto é real sendo essencial implementar medidas que impeçam o desenvolvimento desta micobiota durante a cura do queijo

Aspergilli and Penicillia related to the surface of ripening italian grana type cheese and its ripening environment

Information available on the mycoflora associated to ripening Italian “grana type” cheese is very poor. Recently, ochratoxin A (OTA) was detected in samples of packed grated cheese [1]; therefore, the need of information to perform a risk management was highlighted. Moreover, sterigmatocystin (STC) has been reported in cheese and it is considered an emerging problem. Despite the fact that both of them are mycotoxins included in group 2B by IARC [2,3], no European regulation exists. So, the main goal of this work is to give for the first time a general overview about Penicillia and Aspergilli growing on the surface of ripening “grana type” cheese, with particular attention on mycotoxigenic species. To perform this, in 2013 and 2014 crust samples were scratched from ripening grana cheese wheels and also Potato Dextrose Agar plates were exposed to monitor ripening house air. Then, 140 fungal isolates were randomly chosen, purified and monosporic colonies were obtained for their identification at specie level. A polyphasic approach is followed, based on morphological characterisation, toxic extrolites profiling and gene sequencing. The identification is still in progress, but the first results based on the morphological approach showed the presence of mycotoxigenic Aspergilli (Aspergillus flavus and A. versicolor) and various Penicillium species; among them Penicillium chrysogenum, P. implicatum and P. solitum were identified. Only P. chrysogenum was reported to produce the mycotoxins cyclopiazonic acid (CPA) and roquefortine-C (ROQ-C) [4]. These results will be presented and discussed. [1] A. Biancardi, R. Piro, G. Galaverna, C. Dall’Asta, "A simple and reliable liquid chromatography–tandem mass spectrometry method for determination of ochratoxin A in hard cheese" International Journal of Food Sciences and Nutrition 64 (5), 2013, 632 – 640. [2] International Agency for Research on Cancer (IARC) “IARC Monographs on the Evaluation of Carcinogenic Risks to Humans” 31, 1983, 191 – 199. [3] International Agency for Research on Cancer (IARC) “IARC Monographs on the Evaluation of carcinogenic Risks to Humans”, suppl. 7, 1987, 72. [4] J. I. Pitt, D. A. Hocking, “Fungi and Food Spoilage” 1997, 291

Spatial distribution of ochratoxin A in vineyard and sampling design to assess must contamination.

The aim of this work was to study the spatial variability of ochratoxin A (OTA) in vineyards and to define a reliable sampling protocol for bunches in order to assess OTA content before harvesting. In 2002, two vineyards with 'Negroamaro' and 'Sangiovese' grape varieties were chosen in Southern Italy. The same sampling design was applied to both vineyards. Ten plants were collected from the X-shaped path of the whole vineyard (plants 1 through 10) and 10 plants from the two central cross-perpendicular lines (plants 11 through 20). Bunches harvested from plants 1 through 10 were numbered progressively, weighed, and crushed separately, and bunches obtained from plants 11 through 20 were crushed plant by plant. Juices obtained were analyzed for OTA content by high-performance liquid chromatography. Then, a simulated approach for sampling was applied, following randomized and systematic designs. High and random variability was observed in OTA content both among bunches and among plants in the two vineyards, independent of contamination level. Simulated sampling design markedly influenced the assessment of must contamination. The best results were obtained when sampling involved one bunch per plant, in a predefined position, from at least 10 plants. Estimated means, obtained with different sampling designs, did not differ significantly from calculated mean OTA content. If the true contamination in a vineyard is 2 microg kg(-1), the limit fixed in Europe for OTA content in must and wine, the range of OTA content assessed sampling one bunch in the central position of 10 plants should lie between 2.9 and 1.4. The accuracy could be considered acceptable

Efficacy of chemical and biological spray seed treatments in preventing garlic dry rot

Garlic dry rot caused by Fusarium proliferatum is an emerging postharvest disease that has resulted in severe economic losses, necessitating design and implementation of efficient disease control strategies. Sanitation of planting cloves is critical for preventing garlic dry rot. This study evaluated the efficacy of commercial chemicals and biocontrol agents, applied at planting as spray treatments, for reducing disease severity and the occurrence of Fusarium spp. in garlic, from the field stage then through 9 months of postharvest storage. Tebuconazole was the most effective for reducing disease severity, giving 26.5% reduction of basal plate rots and 44% reduction of bulb rots, and 33.4% reduction in visible symptoms on cloves relative to the untreated controls. Comparable results were obtained by applying B. subtilis and S. griseoviridis. However, none of the active ingredients tested in this study reduced the incidence of F. oxysporum and F. proliferatum on basal plates, although tebuconazole reduced the postharvest incidence of F. proliferatum on cloves by nearly 50%. Incidence of F. proliferatum increased by 37% in bulbs transferred from storage to room temperature (25°C) for 15 days, simulating storage in consumers' homes. These results demonstrate that spray seed clove treatments have inhibitory effects on postharvest garlic dry rot, although further research is required to determine the persistence of these treatments during prolonged storage, especially without low temperatures