Factores extrínsecos e intrínsecos asociados a poblaciones fúngicas micotoxigénicas de granos de maíz (Zea mays L.) almacenados en silos bolsa en Argentina

Abstract

In order to determine the behavior of mycotoxin-producing fungal populations linked with silobags stored corn grains with a moisture content greater at the recommended as safe, 270 samples taken in three times (beginning, 90 days, final) over a five month period of storage were evaluated. The fungal biota was quantified and identified and the contamination with fumonisin and aflatoxin was determined. Extrinsic factors (environment), intrinsic factors (grains) and technological factors (location of the grains in the profile of silobag) were taken into account to evaluate the presence and quantity of total and mycotoxigenic fungal populations. The pH of grains and O2 levels were significantly reduced after five months, while CO2 concentration increased in the same period. The total counts of mycobiota were significantly higher in grains located in the top layer of silobag. Mycotoxigenic species of Fusarium, Aspergillus, Penicillium and Eurotium were identified. The frequency of isolation of Fusarium verticillioides decreased at the end of storage and Aspergillus flavus was isolated only at the beginning of storage. The counts of the Penicillium spp. and Eurotium spp. were increased at the end of storage. Fumonisin contamination was found in all the samples (100%) with maximum levels of 5.707mg/kg whereas aflatoxin contaminated only 40% with maximum levels of 0.0008mg/kg. The environmental and substrate conditions generated during the storage limited the development of mycotoxigenic fungi and mycotoxin production.

Fungal diversity and mycotoxins detected in maize stored in silo‐bags: a review

“…In maize stored in silo‐bags, the presence of several toxicogenic species of the genus Penicillium was reported. Penicillium roqueforti , P. crustosum and P. paneum are species capable of producing PR toxin, mycophenolic acid and roquefortine C, 3,45 whereas P. citrinum and P. verrucosum are potential citrinin producers 17 . Although PR toxin is rarely detected in silage, mycophenolic acid and roquefortins are the most studied Penicillium toxins in silage forage 33 .…”

“…Aspergillus is a xerophilic fungus that can develop in grains stored with low moisture content, whereas Fusarium presents greater development in grains with higher moisture content. Although Aspergillus is favored by dry storage conditions, some species are well adapted to substrates with alkaline pH, and so an acidic pH of silo‐bags could affect the survival of these species, 17 such that there are only four species of this genus. Fungi that resist low concentrations of O 2 and acid pH are frequent contaminants of silo‐bags, such as A. fumigatus 45 .…”

“…One of the most important crops that are currently stored in silo‐bags are maize grains. The maize to be stored must have a moisture content below 14% dry weight so that the risk of contamination during the storage process is low 17 . If the silo‐bag loses its hermetic nature or the maize grains are stored with a higher moisture content than recommended, the development of fungi and the production of mycotoxins is favored, triggering the deterioration of the stored grains.…”

INTERACCIONES ENTRE Fusarium verticillioides (Sacc.) Nirenberg, Aspergillus flavus Link Y Talaromyces funiculosus Thom EN AMBIENTES HERMÉTICOS

“…En ambos tiempos de muestreo se registraron las concentraciones de O 2 y CO 2 en las bolsas (in situ) con un medidor de gases portátil (Check Point, PBI, DanSensor, Dinamarca) y el pH de los granos de las muestras, en el laboratorio con un peachímetro digital y portátil (Oakton modelo PH11, N° serie 203852), según protocolo de Castellari et al (2015).…”

“…Las especies micotoxigénicas aisladas de granos de maíz con mayor frecuencia pertenecen a los géneros Fusarium y Aspergillus (Gregori et al, 2013) mientras que las especies de Penicillium y Talaromyces son las que se aíslan con mayor frecuencia entre las poblaciones no micotoxigénicas (Castellari et al, 2015). Los resultados del análisis de micotoxinas en maíz revelaron que entre el 90 y 100% de las muestras están contaminadas con fumonisinas (FB) (Pacin et al, 2009) el 10% con zearalenona y deoxinivalenol, y entre el 10 y 50% con aflatoxinas (AF) (Garrido et al, 2012).…”