Time-course of germination, initiation of mycelium proliferation and probability of visible growth and detectable AFB1 production of an isolate of Aspergillus flavus on pistachio extract agar

dc.contributor.authorAldars García, Laila
dc.contributor.authorSanchís Almenar, Vicente
dc.contributor.authorRamos Girona, Antonio J.
dc.contributor.authorMarín Sillué, Sònia
dc.description.abstractThe aim of this work was to assess the temporal relationship among quantified germination, mycelial growth and aflatoxin B1 (AFB1) production from colonies coming from single spores, in order to find the best way to predict as accurately as possible the presence of AFB1 at the early stages of contamination. Germination, mycelial growth, probability of growth and probability of AFB1 production of an isolate of Aspergillus flavus were determined at 25 °C and two water activities (0.85 and 0.87) on 3% Pistachio Extract Agar (PEA). The percentage of germinated spores versus time was fitted to the modified Gompertz equation for the estimation of the germination parameters (geometrical germination time and germination rate). The radial growth curve for each colony was fitted to a linear model for the estimation of the apparent lag time for growth and the growth rate, and besides the time to visible growth was estimated. Binary data obtained from growth and AFB1 studies were modeled using logistic regression analysis. Both water activities led to a similar fungal growth and AFB1 production. In this study, given the suboptimal set conditions, it has been observed that germination is a stage far from the AFB1 production process. Once the probability of growth started to increase it took 6 days to produce AFB1, and when probability of growth was 100%, only a 40–57% probability of detection of AFB1 production was predicted. Moreover, colony sizes with a radius of 1–2 mm could be a helpful indicator of the possible AFB1 contamination in the commodity. Despite growth models may overestimate the presence of AFB1, their use would be a helpful tool for producers and manufacturers; from our data 5% probability of AFB1 production (initiation of production) would occur when a minimum of 60% probability of growth is observed. Legal restrictions are quite severe for these toxins, thus their control from the early stages of contamination throughout the food chain is of paramount importance.ca_ES
dc.description.sponsorshipThe authors are grateful to the Agència de Gestió d’Ajuts Universitaris i de Recerca de la Generalitat de Catalunya (AGAUR, grant 2014FI_B 00045), and to the Spanish Ministry of Economy and Competitiveness (MINECO, Project AGL2014-55379-P) for funding this work.ca_ES
dc.relation.isformatofReproducció del document publicat a https://doi.org/10.1016/j.fm.2016.12.015ca_ES
dc.relation.ispartofFood Microbiology, 2017, vol. 64, p. 104-111ca_ES
dc.rights(c) Elsevier Ltd. 2016ca_ES
dc.subjectAflatoxin probabilityca_ES
dc.subjectPredictive mycologyca_ES
dc.titleTime-course of germination, initiation of mycelium proliferation and probability of visible growth and detectable AFB1 production of an isolate of Aspergillus flavus on pistachio extract agarca_ES
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