Mycotoxins, the secondary metabolites of mycotoxigenic fungi, have been found in almost all agricultural commodities worldwide, causing enormous economic losses in livestock production and severe human health problems. Compared to traditional physical adsorption and chemical reactions, interest in biological detoxification methods that are environmentally sound, safe and highly efficient has seen a significant increase in recent years. However, researchers in this field have been facing tremendous unexpected challenges and are eager to find solutions. This review summarizes and assesses the research strategies and methodologies in each phase of the development of microbiological solutions for mycotoxin mitigation. These include screening of functional microbial consortia from natural samples, isolation and identification of single colonies with biotransformation activity, investigation of the physiological characteristics of isolated strains, identification and assessment of the toxicities of biotransformation products, purification of functional enzymes and the application of mycotoxin decontamination to feed/food production. A full understanding and appropriate application of this tool box should be helpful towards the development of novel microbiological solutions on mycotoxin detoxification.

Patulin is a mycotoxin that primarily contaminate apples and apple products. Whole cell or cell-free extracts of Gluconobacter oxydans ATCC 621 were able to transform patulin to E-ascladiol. Proteins from cell-free extracts were separated by anion exchange chromatography and fractions with patulin transformation activity were subjected to peptide mass fingerprinting, enabling the identification of two NADPH dependent short chain dehydrogenases, GOX0525 and GOX1899, with the requisite activity. The genes encoding these enzymes were expressed in E. coli and purified. Kinetic parameters for patulin reduction, as well as pH profiles and thermostability were established to provide further insight on the potential application of these enzymes for patulin detoxification.

Deoxynivalenol (DON) is a secondary fungal metabolite and contaminant mycotoxin that is widely detected in wheat and corn products cultivated around the world. Bio-remediation methods have been extensively studied in the past two decades and promising ways to reduce DON-associated toxicities have been reported. Bacterial epimerization of DON at the C3 carbon was recently reported to induce a significant loss in the bio-toxicity of the resulting stereoisomer (3-epi-DON) in comparison to the parental compound, DON. In an earlier study, we confirmed the diminished bio-potency of 3-epi-DON using different mammalian cell lines and mouse models and mechanistically attributed it to the reduced binding of 3-epi-DON within the ribosomal peptidyl transferase center (PTC). In the current study and by inspecting the chromatographic behavior of 3-epi-DON and its molecular interactions with a well-characterized enzyme, Fusarium graminearum Tri101 acetyltransferase, we provide the evidence that the C3 carbon epimerization of DON influences its molecular interactions beyond the abrogated PTC binding.

Deoxynivalenol (DON) is a secondary fungal metabolite that is associated with many adverse toxicological effects in agriculture as well as human/animal nutrition. Bioremediation efforts in recent years have led to the discovery of numerous bacterial isolates that can transform DON to less toxic derivatives. Both 3-keto-DON and 3-epi-DON were recently shown to exhibit reduced toxicity, compared to DON, when tested using different cell lines and mammalian models. In the current study, the toxicological assessment of 3-keto-DON and 3-epi-DON using in planta models surprisingly revealed that 3-keto-DON, but not 3-epi-DON, retained its toxicity to a large extent in both duckweeds (Lemna minor L.) and common wheat (Triticum aestivum L.) model systems. RNA-Seq analysis revealed that the exposure of L. minor to 3-keto-DON and DON resulted in substantial transcriptomic changes and similar gene expression profiles, whereas 3-epi-DON did not. These novel findings are pivotal for understanding the environmental burden of the above metabolites as well as informing the development of future transgenic plant applications. Collectively, they emphasize the fundamental need to assess both plant and animal models when evaluating metabolites/host interactions.

DepA, a pyrroloquinoline quinone (PQQ)-dependent enzyme isolated from Devosia mutans 17-2-E-8, exhibits versatility in oxidizing deoxynivalenol (DON) and its derivatives. This study explored DepA’s substrate specificity and enzyme kinetics, focusing on DON and 15-acetyl-DON. Besides efficiently oxidizing DON, DepA also transforms 15-acetyl-DON into 15-acetyl-3-keto-DON, as identified via LC-MS/MS and NMR analysis. The kinetic parameters, including the maximum reaction rate, turnover number, and catalytic efficiency, were thoroughly evaluated. DepA-PQQ complex docking was deployed to rationalize the substrate specificity of DepA. This study further delves into the reduced toxicity of the transformation products, as demonstrated via enzyme homology modeling and in silico docking analysis with yeast 80S ribosomes, indicating a potential decrease in toxicity due to lower binding affinity. Utilizing the response surface methodology and central composite rotational design, mathematical models were developed to elucidate the relationship between the enzyme and cofactor concentrations, guiding the future development of detoxification systems for liquid feeds and grain processing. This comprehensive analysis underscores DepA’s potential for use in mycotoxin detoxification, offering insights for future applications.

Pulses, the dried seeds of leguminous plants, form an important part of the diets of many cultures, including Caribbean cuisine, and are a rich source of protein, carbohydrates, and antioxidants while being low in fats. This study examined the effect of a traditional home-cooking method on the nutritional characteristics of pulses commonly consumed in the Caribbean: red kidney beans and cranberry beans (Phaseolus vulgaris L.), cowpeas (Vigna unguiculata L.), and pigeon peas (Cajanus cajan L.). Protein quality, determined via three in vitro protein digestibility methods, starch, and phenolic content were determined in pre- and post-cooked samples using established methods. Pulses contained 20–26% protein, and cooking improved protein digestibility on average by 14.0 ± 2.5% (p < 0.05). However, notable differences in digestibility were observed: it was higher in static assays (pH-Drop and pH-Stat) than in the two-step digestibility assay. Average protein digestibility-corrected amino acid score (IVPDCAAS) among cooked pulses was 0.81 ± 0.14, with the highest in cranberry bean (0.82) and cowpea (0.88). Cooking modified pulse starch profiles by increasing total digestible starch. However, resistant starch and slowly digestible starch fractions accounted for approximately 20–25% of total cooked starch content. While total phenolic content (TPC) and antioxidant activity were reduced with cooking, they were within expected ranges for cooked pulse flours; however, they were higher in bean (P. vulgaris) varieties than cowpea and pigeon pea. These findings support the promotion of increased pulse consumption in Caribbean diets. Home cooking is a simple method to enhance pulse protein quality through enhancing digestibility; however, in vitro protein digestibility assays may require further standardization.