Incidence of Penicillium verrucosum in Grain Samples from Oat Varieties Commonly Grown in South Dakota

Abstract

Ochratoxin A (OTA) can cause toxicogenic effects in humans and animals when contaminated food products are consumed. Oat ( Avena sativa), like any other cereal grain, can be contaminated with OTA when storage conditions are favorable for fungal growth and toxin production. South Dakota is among the leading oat-producing states in the United States. It is therefore important to determine the frequency of occurrence of the primary OTA-producing fungal species on oat grains produced in the state. In this study, we evaluated oat grain samples from South Dakota for the incidence of Penicillium verrucosum, the major ochratoxigenic fungus in temperate regions. Kernels from 12 oat cultivars grown at multiple locations in South Dakota from 2014 to 2016 (15 location-year combinations) were plated on dichloran yeast extract sucrose glycerol agar medium. P. verrucosum was detected on 0.30, 0.19, and 0.05% of the kernels tested in 2014, 2015, and 2016, respectively. Overall, 22 of the 360 evaluated samples had kernels contaminated with P. verrucosum. The fungal incidence of the contaminated samples ranged from 1 to 16%, and the majority of those samples originated from one location. All samples from 2014 and 2015 ( n = 240), except two, had no detectable levels of OTA. The concentration of OTA was well under the maximum limit recommended by the European Union for the two samples with detectable levels of OTA.

Identification of Penicillium verrucosum, Penicillium commune, and Penicillium crustosum Isolated from Chicken Eggs

“…The main advantage of this method is that no special equipment is required and the method can be used to identify a wide range of different microorganisms without the need to change the analytical procedure. Thus, the suitability of PCR-ITS-RFLP method for identification of microscopic filamentous fungi has also been confirmed in other studies [12,17,[56][57][58].…”

“…The restriction fragment length polymorphism (RFLP) can be used to distinguish variations in the DNA sequences that may not be expressed at the protein level [14,15]. P. verrucosum, P. commune, and P. crustosum are frequently reported causes of spoilage in wide range of plant food and food materials [16][17][18]. Moreover, P. verrucosum is known for production of ochratoxin A [19] and citrinin [20], and P. crustosum is capable of producing penitrem A [21] and roquefortine C [20].…”

Effect of oat cultivar on ochratoxin A accumulation following grain inoculation with Penicillium verrucosum

“…Cultivars differed for maturity and disease resistance (data not shown), as well as in grain characteristics and composition (Table ). Grain samples were either free of P. verrucosum infestation (98.8% of the samples) or had an infestation frequency of ≤1% (Dhungana et al, ). Ochratoxin A concentration was lower than the detection limit (0.1 ppb) in all samples except two for which OTA was less than 1 ppb (Dhungana et al, ).…”

“…Grain samples were either free of P. verrucosum infestation (98.8% of the samples) or had an infestation frequency of ≤1% (Dhungana et al, 2018). Ochratoxin A concentration was lower than the detection limit (0.1 ppb) in all samples except two for which OTA was less than 1 ppb (Dhungana et al, 2018). Competition between P. verrucosum and other fungal species such as Aspergillus flavus may inhibit OTA production (Ramakrishna, Lacey, & Smith, 1996); therefore, all the oat samples were sterilized with gamma irradiation prior to inoculation with P. verrucosum strain C84-2.…”

“…One hundred sixty‐five grain samples from the South Dakota Crop Performance Testing Oat Variety Trials were used in the study. All samples were examined for the presence of P. verrucosum by plating in DYSG media (Dhungana, Ali, Byamukama, Krishnan, & Caffe‐Treml, ). Samples were from twelve oat cultivars commonly grown in South Dakota (Colt, Deon, Goliath, Hayden, Horsepower, Jerry, Jury, Natty, Newburg, Shelby 427, Rockford, and Stallion).…”