Conidia survival of Aspergillus section Nigri, Flavi and Circumdati under UV-A and UV-B radiation with cycling temperature/light regime.

BACKGROUND: Bio-geographical differences in fungal infection distribution have been observed around the world, confirming that climatic conditions are decisive in colonization. This research is focused on the impact of ultraviolet radiation (UV) on Aspergillus species, based on the consideration that an increase in UV-B radiation may have large ecological effects. RESULTS: Conidia of six mycotoxigenic Aspergillus species isolated from vineyards located in the northeast and south of Spain were incubated for 15 days under light/dark cycles and temperatures between 20 and 30 °C per day. Additionally, 6 h of exposure to UV-A or UV-B radiation per day were included in the light exposure. UV irradiance used were 1.7 ± 0.2 mW cm(-2) of UV-A (peak 365 nm) and 0.10 ± 0.2 mW cm(-2) of UV-B (peak 312 nm). The intrinsic decrease in viability of conidia over time was accentuated when they were UV irradiated. UV-B radiation was more harmful. CONCLUSION: Conidial sensitivity to UV light was marked in Aspergillus section Circumdati. Conidia pigmentation could be related to UV sensitivity. Different resistance was observed within species belonging to sections Flavi and Nigri. An increase in UV radiation could lead to a reduction in the Aspergillus spp. inoculum present in the field (vineyards, nuts, cereal crops). In addition, it could unbalance the spore species present in the field, leading to a higher predominance of dark-pigmented conidia.

Ochratoxigenic moulds and effectiveness of grape field antifungals in a climatic change scenario.

BACKGROUND: The presence of ochratoxin A (OTA) in grapes and grape derivatives has been reported mainly in the Mediterranean area. Consequently, great efforts are being made to prevent the growth of Aspergillus on grapes. However, the European Commission suggests that climate change may result in increased temperatures and longer drought periods in southern Europe. Therefore the aim of this study was to investigate how ochratoxigenic fungal growth and the efficiency of fungicides used at present might be affected by environmental conditions predicted with climate change. RESULTS: The effectiveness of grape field antifungals (Switch, Flint Max and Equisetum arvense extract) under two alternating temperature, photoperiod and relative humidity (RH) scenarios (current: 20/30 °C, 16 h light/8 h darkness, 80% RH; predicted: 25/37 °C, 16 h light/8 h darkness, 75% RH) on the growth and OTA production of two Aspergillus carbonarius isolates and one Aspergillus ochraceus isolate on grapes was investigated. CONCLUSION: Predicted conditions reduced A. carbonarius and limited A. ochraceus growth. Antifungals reduced fungal infection (by 40-84%), although no correlation between climatic conditions and effectiveness of the antifungals was found. However, Switch always showed the greatest reduction and E. arvense (0.02 g mL(-1) extract) the least. Higher temperatures affected OTA production by the isolates in different ways. In general, Switch and Flint Max reduced OTA production, while E. arvense stimulated it.

Early detection of fungal growth in bakery products by use of an electronic nose based on mass spectrometry.

This paper presents the design, optimization, and evaluation of a mass spectrometry-based electronic nose (MS e-nose) for early detection of unwanted fungal growth in bakery products. Seven fungal species (Aspergillus flavus, Aspergillus niger, Eurotium amstelodami, Eurotium herbariorum, Eurotium rubrum, Eurotium repens, and Penicillium corylophillum) were isolated from bakery products and used for the study. Two sampling headspace techniques were tested: static headspace (SH) and solid-phase microextraction (SPME). Cross-validated models based on principal component analysis (PCA), coupled to discriminant function analysis (DFA) and fuzzy ARTMAP, were used as data treatment. When attempting to discriminate between inoculated and blank control vials or between genera or species of in vitro growing cultures, sampling based on SPME showed better results than those based on static headspace. The SPME-MS-based e-nose was able to predict fungal growth with 88% success after 24 h of inoculation and 98% success after 48 h when changes were monitored in the headspace of fungal cultures growing on bakery product analogues. Prediction of the right fungal genus reached 78% and 88% after 24 and 96 h, respectively.