Enzymatic degradation is an effective means to reduce aflatoxin contamination in maize

Abstract

Background Aflatoxins are carcinogenic compounds produced by certain species of Aspergillus fungi. The consumption of crops contaminated with this toxin cause serious detrimental health effects, including death, in both livestock and humans. As a consequence, both the detection and quantification of this toxin in food/feed items is tightly regulated with crops exceeding the allowed limits eliminated from food chains. Globally, this toxin causes massive agricultural and economic losses each year. Results In this paper we investigate the feasibility of using an aflatoxin-degrading enzyme strategy to reduce/eliminate aflatoxin loads in developing maize kernels. We used an endoplasmic reticulum (ER) targeted sub-cellular compartmentalization stabilizing strategy to accumulate an aflatoxin-degrading enzyme isolated from the edible Honey mushroom Armillariella tabescens and expressed it in embryo tissue in developing maize kernels. Three transgenic maize lines that were determined to be expressing the aflatoxin-degrading enzyme both at the RNA and protein level, were challenged with the aflatoxin-producing strain Aspergillus flavus AF13 and shown to accumulate non-detectable levels of aflatoxin at 14-days post-infection and significantly reduced levels of aflatoxin at 30-days post-infection compared to nontransgenic control Aspergillus-challenged samples. Conclusions The expression of an aflatoxin-degrading enzyme in developing maize kernels was shown to be an effective means to control aflatoxin in maize in pre-harvest conditions. This aflatoxin-degradation strategy could play a significant role in the enhancement of both US and global food security and sustainability.

Aflatoxin biocontrol in practice requires a multidisciplinary, long-term approach

“…There are publications and/or news articles showcasing GMOs as the panacea for aflatoxin control. Transgenic events can lead to reduced aflatoxin levels in genetically modified maize and groundnut under controlled conditions (Thakare et al, 2017;Sharma et al, 2018;Schmidt et al, 2021) but such testing has not been done in field conditions. Programs using transgenic crops to reduce aflatoxin contamination, when and if commercially available, must know basic information about transgenes to effectively communicate with stakeholders and must provide science-based answers in a layman language to address questions on the use and safety of transgenic cultivars.…”

Enzymatic Degradation of Aflatoxin Accumulation in Dry Maize Kernels as A Promising Post-Harvest Mitigation Strategy

“…A promising post-harvest decontamination strategy involves the enzymatic conversation of aflatoxin to innocuous compounds. Prior research [20] demonstrated the successful pre-harvest degradation of aflatoxin from contaminating A. flavus conditions in developing maize kernels that were expressing an endoplasmic reticulum (ER)-targeted embryo-expressed aflatoxin-degrading enzyme isolated from the edible Honey mushroom (Armillariella tabescens) [21]. In this research, we investigate if reducing /eliminating aflatoxin by enzymatic degradation in maize kernels would also be an effective post-harvest strategy in dry stored kernels.…”

“…Dry kernels were harvested from a control nontransgenic maize plant (Null) and three independent transgenic maize lines (Enz7, Enz8, Enz10) (Zea mays Hi II hybrid A 188 and B73 background) previously shown to be expressing an inserted aflatoxin-degrading enzyme (GenbankAccession AY941095) [20]. The inserted cassette in these transgenic maize plants consisted of a codon-optimized 2.166 kb open reading frame of an ER-targeted aflatoxindegrading enzyme expressed by an embryo-specific maize globulin-1 promoter (Genbank Accession AH001354.2) [20]. Cobs from three transgenic lines (Enz 7, Enz 8, and Enz 10) and the nontransgenic maize line (Null) were removed from ears grown in the greenhouse.…”

Natural Antioxidant By-Product Mixture Counteracts the Effects of Aflatoxin B1 and Ochratoxin A Exposure of Piglets after Weaning: A Proteomic Survey on Liver Microsomal Fraction

“…In humans, AFB1 exposure has been linked to liver cancer, as well as other health problems such as immune suppression, stunted growth, and decreased cognitive function [24][25][26][27][28][29][30]. Also, OTA has been shown to cause kidney toxicity in humans, increased risk of cancer, decreased immunity, and oxidative stress [31][32][33][34][35].…”