Deterrence of Aspergillus Flavus Regrowth and Aflatoxin Accumulation on Shelled Corn Using Infrared Heat Treatments

HighlightsInfrared heating was used to deactivate Aspergillus flavus.Treating samples for 150 s at the 3.24 kW/m2 intensity resulted in complete deactivation of A. flavus.Adding a tempering step at 70°C for 4 h significantly increased deactivation of A. flavus.Corn treated at IR intensity =3.24 kW/m2 showed no potential for A. flavus regrowth or aflatoxin persistence.The study demonstrated a non-chemical approach to deactivate mycotoxigenic fungi on corn.Abstract.The objectives of this study were to determine the suitable combinations of infrared (IR) heating duration and intensity, followed by tempering treatments to maximize the deactivation of aflatoxin-producing mold spores, specifically Aspergillus flavus (A. flavus). Corn samples at moisture content of 24% wet basis were inoculated with spore suspension of A. flavus and incubated to allow microbial attachment on the kernels. Corn samples were then heated using IR energy and then tempered for 4 h. Following the treatments, the samples were placed in conditions favorable for mold regrowth. Treatments of non-tempered samples for 210 s at the lowest intensity (1.27 kW/m2) resulted in A. flavus load reductions of 5.9 Log CFU/g. Treatments of non-tempered samples at the medium (3.24 kW/m2) and highest intensity (6.9 kW/m2) for 210 s resulted in complete deactivation of A. flavus. No fungal regrowth or aflatoxin persistence was observed on samples treated for 210 s at the lowest, medium, and highest IR intensities. Keywords: Aflatoxins, Aspergillus flavus, Infrared heating, Shelled corn, Tempering.

Download Full-text

Decontamination of Mycotoxigenic Fungi on Shelled Corn Using Selective Infrared Heating Technique

Cereal Chemistry ◽

10.1002/cche.10394 ◽

2020 ◽

Author(s):

Shantae A. Wilson ◽

Zeinab Mohammadi Shad ◽

Abass A. Oduola ◽

Zonghui Zhou ◽

Hongrui Jiang ◽

...

Keyword(s):

Infrared Heating ◽

Mycotoxigenic Fungi

Download Full-text

Characterization of the Maize Chitinase Genes and Their Effect on Aspergillus flavus and Aflatoxin Accumulation Resistance

PLoS ONE ◽

10.1371/journal.pone.0126185 ◽

2015 ◽

Vol 10 (6) ◽

pp. e0126185 ◽

Cited By ~ 33

Author(s):

Leigh K. Hawkins ◽

J. Erik Mylroie ◽

Dafne A. Oliveira ◽

J. Spencer Smith ◽

Seval Ozkan ◽

...

Keyword(s):

Aspergillus Flavus ◽

Aflatoxin Accumulation ◽

Chitinase Genes

Download Full-text

Modelling the colonisation of maize by toxigenic and non-toxigenic Aspergillus flavus strains: implications for biological control

World Mycotoxin Journal ◽

10.3920/wmj2008.x036 ◽

2008 ◽

Vol 1 (3) ◽

pp. 333-340 ◽

Cited By ~ 17

Author(s):

H. Abbas ◽

R. Zablotowicz ◽

H. Bruns

Keyword(s):

Biological Control ◽

Aspergillus Flavus ◽

Growth Parameters ◽

Biological Control Agent ◽

Cyclopiazonic Acid ◽

Aflatoxin Contamination ◽

Tween 20 ◽

Lag Phase ◽

Gompertz Equation ◽

Aflatoxin Accumulation

To successfully exploit biological control it is desirable to understand how the introduced agent colonises the host and interferes with establishment of the pest. This study assessed field colonisation of maize by Aspergillus flavus strains as biological control agents to reduce aflatoxin contamination. Maize (corn, Zea mays L.) ears were inoculated with A. flavus using a pin-bar technique in 2004 and 2005. Non-aflatoxigenic strains K49 (NRRL 30797) & CT3 (NRRL 30798) and toxigenic F3W4 (NRRL 30798) were compared against a carrier control (0.2% aqueous Tween 20). Ten ears were sampled over 12 to 20 days, visually assessed, and curves fit to a three compartment Gompertz equation or other best appropriate regressions. Aflatoxin was determined by HPLC and cyclopiazonic acid (CPA) by LC/MS. The Gompertz model describes growth parameters, e.g. growth constant, lag phase and maximum colonisation characterised patterns of maize colonisation for most inoculated treatments. Aflatoxin accumulation in maize inoculated with F3W4 was about 35,000 ng/g in 2004 and 2005, with kinetics of aflatoxin accumulation in 2005 well described by the Gompertz equation. Less than 200 ng/g was observed in maize inoculated with strains CT3 & K49 and accumulation was described by a linear or logistic model. Maize inoculated with strains CT3 and F3W4 accumulated a maximum of 220 and 169 µg/kg CPA, respectively, compared to 22 and 0.2 µg/kg in the control and K49 inoculated, respectively. This technique can be used to elucidate colonisation potential of non-toxigenic A. flavus in maize in relation to biological control of aflatoxin. The greatest reduction of aflatoxin and CPA in maize inoculated with strain K49 and Gompertz parameters on colonisation indicates its superiority to CT3 as a biological control agent. The dynamics of maize colonisation by A. flavus strains and subsequent mycotoxin accumulation generated by using the pin-bar technique has implications for characterising the competence of biocontrol strains for reducing aflatoxin contamination.

Download Full-text

Mycoflora in Commercial Pet Foods

Journal of Food Protection ◽

10.4315/0362-028x-64.5.741 ◽

2001 ◽

Vol 64 (5) ◽

pp. 741-743 ◽

Cited By ~ 13

Author(s):

DANTE J. BUENO ◽

JULIO O. SILVA ◽

GUILLERMO OLIVER

Keyword(s):

Aspergillus Niger ◽

Moisture Content ◽

Aspergillus Flavus ◽

Aspergillus Terreus ◽

Animal Health ◽

Mold Growth ◽

Mucor Racemosus ◽

Isolation Frequency ◽

Mycelia Sterilia ◽

Made In

This article reports on the identification of mycoflora of 21 dry pet foods (12 belonging to dogs and 9 to cats) that corresponded to 8 commercial brands made in Argentina and imported. The isolation frequency and relative density of the prevalent fungal genera are compared too. Ten genera and fungi classified as Mycelia sterilia were identified. The predominant genera were Aspergillus (62%), Rhizopus (48%), and Mucor (38%). The most prevalent among Aspergillus was Aspergillus flavus followed by Aspergillus niger and Aspergillus terreus. The predominant Mucor was Mucor racemosus followed by Mucor plumbeus and Mucor globosus. The moisture content of these foods ranged from 5.6 to 10.0% and from 7.2 to 9.9% for dog and cat foods, respectively. A greater moisture content in food for the senior category (9.5 ± 0.2) was observed only in comparison to adult and kitten/puppy. If the moisture content can be maintained at these levels, mold growth would be prevented or at least it would remain at an insignificant level. Some genera and species isolated and identified from the foods analyzed are potentially producing toxins, which are known as mycotoxins. This involves a risk for animal health.

Download Full-text

Antifungal activities of thiosemicarbazones and semicarbazones against mycotoxigenic fungi

Ciência e Agrotecnologia ◽

10.1590/s1413-70542014000600001 ◽

2014 ◽

Vol 38 (6) ◽

pp. 531-537 ◽

Cited By ~ 6

Author(s):

Rojane de Oliveira Paiva ◽

Lucimar Ferreira Kneipp ◽

Carla Marins Goular ◽

Mariana Almeida Albuquerque ◽

Aurea Echevarria

Keyword(s):

Antifungal Activity ◽

Aspergillus Flavus ◽

Fungicidal Activity ◽

Fusarium Verticillioides ◽

Animal Health ◽

Fungistatic Activity ◽

Mycotoxigenic Fungi ◽

Quality Of Food ◽

Chelating Effect

Mycotoxigenic fungi can compromise the quality of food, exposing human and animal health at risk. The antifungal activity of eight thiosemicarbazones (1-8) and nine semicarbazones (9-17) was evaluated against Aspergillus flavus, A. nomius, A. ochraceus, A. parasiticus and Fusarium verticillioides. Thiosemicarbazones had MIC values of 125-500 µg/ml. The thiosemicarbazones 1 and 2 exerted fungistatic activity against Aspergillus spp., and thiosemicarbazone 2 exerted fungicidal activity against F. verticillioides. Compound 2 showed an iron chelating effect of 63%. The ergosterol content of A. parasiticus had a decrease of 28 and 71% for the 31.2 and 62.5 µg/ml concentrations of thiosemicarbazone 2 compared to the control. The obtained results of antifungal activity revealed that thiosemicarbazone class was more active when compared to semicarbazone class and, the thiosemicarbazone 2 was the most active compound, specially, against Aspergillus spp.

Download Full-text

Nonaflatoxigenic Aspergillus flavus TX9-8 competitively prevents aflatoxin accumulation by A. flavus isolates of large and small sclerotial morphotypes

International Journal of Food Microbiology ◽

10.1016/j.ijfoodmicro.2006.09.017 ◽

2007 ◽

Vol 114 (3) ◽

pp. 275-279 ◽

Cited By ~ 22

Author(s):

Perng-Kuang Chang ◽

Sui-Sheng T. Hua

Keyword(s):

Aspergillus Flavus ◽

Aflatoxin Accumulation

Download Full-text

Interactions of Saprophytic Yeasts with anor Mutant of Aspergillus flavus

Applied and Environmental Microbiology ◽

10.1128/aem.65.6.2738-2740.1999 ◽

1999 ◽

Vol 65 (6) ◽

pp. 2738-2740 ◽

Cited By ~ 47

Author(s):

Sui-Sheng T. Hua ◽

James L. Baker ◽

Melanie Flores-Espiritu

Keyword(s):

Aspergillus Flavus ◽

Agar Plate ◽

Aflatoxin Production ◽

Aflatoxin Contamination ◽

Orange Pigment ◽

Yeast Strains ◽

Norsolorinic Acid ◽

Aflatoxin Accumulation ◽

Food Commodities ◽

Pigment Accumulation

ABSTRACT The nor mutant of Aspergillus flavus has a defective norsolorinic acid reductase, and thus the aflatoxin biosynthetic pathway is blocked, resulting in the accumulation of norsolorinic acid, a bright red-orange pigment. We developed a visual agar plate assay to monitor yeast strains for their ability to inhibit aflatoxin production by visually scoring the accumulation of this pigment of the nor mutant. We identified yeast strains that reduced the red-orange pigment accumulation in the normutant. These yeasts also reduced aflatoxin accumulation by a toxigenic strain of A. flavus. These yeasts may be useful for reducing aflatoxin contamination of food commodities.

Download Full-text

Aspergillus flavus NRRL 35739, a Poor Biocontrol Agent, May Have Increased Relative Expression of Stress Response Genes

Journal of Fungi ◽

10.3390/jof5020053 ◽

2019 ◽

Vol 5 (2) ◽

pp. 53 ◽

Cited By ~ 2

Author(s):

Kayla K. Pennerman ◽

Guohua Yin ◽

Joan W. Bennett ◽

Sui-Sheng T. Hua

Keyword(s):

Stress Response ◽

Aspergillus Flavus ◽

Genetic Basis ◽

Biocontrol Agent ◽

Success Rates ◽

Lower Stress ◽

Relative Expression ◽

Stress Response Genes ◽

Variable Success ◽

Aflatoxin Accumulation

Biocontrol of the mycotoxin aflatoxin utilizes non-aflatoxigenic strains of Aspergillus flavus, which have variable success rates as biocontrol agents. One non-aflatoxigenic strain, NRRL 35739, is a notably poor biocontrol agent. Its growth in artificial cultures and on peanut kernels was found to be slower than that of two aflatoxigenic strains, and NRRL 35739 exhibited less sporulation when grown on peanuts. The non-aflatoxigenic strain did not greatly prevent aflatoxin accumulation. Comparison of the transcriptomes of aflatoxigenic and non-aflatoxigenic A. flavus strains AF36, AF70, NRRL 3357, NRRL 35739, and WRRL 1519 indicated that strain NRRL 35739 had increased relative expression of six heat shock and stress response proteins, with the genes having relative read counts in NRRL 35739 that were 25 to 410 times more than in the other four strains. These preliminary findings tracked with current thought that aflatoxin biocontrol efficacy is related to the ability of a non-aflatoxigenic strain to out-compete aflatoxigenic ones. The slower growth of NRRL 35739 might be due to lower stress tolerance or overexpression of stress response(s). Further study of NRRL 35739 is needed to refine our understanding of the genetic basis of competitiveness among A. flavus strains.

Download Full-text