Reducing Competition of Pepsin in Aflatoxin Adsorption by Modifying a Smectite with Organic Nutrients

Natural smectites bind aflatoxins from water effectively, but the complex chemical environment in the guts of mammals and other animals can limit binding of aflatoxins. Many efforts have been made to enhance the adsorption capacity and affinity of smectites for aflatoxins in the presence of biological compounds. The main objective of the present study was to modify smectite structures by pillaring and cation exchange to enhance aflatoxin B1 adsorption capacity and selectivity. Smectite was pillared with Al and Al-Fe polycations or saturated with Ca, Mg, Zn, or Li. Structural changes in smectites with or without heat treatment were determined using X-ray diffraction and Fourier-transform infrared spectroscopy. Equilibrium aflatoxin B1 adsorption to the smectites was measured in aqueous solution and in simulated gastric fluid. Pillaring with the polycations expanded smectites in the z-direction to 18.6 Å and the expansion was stable after heating at 500°C. Changes in the Al–OH–Al infrared bands in the stretching region supported the formation of pillared clays. Migration of Mg, Zn, and Li into the octahedral sites of the smectite was observed as Mg and Zn saturation yielded a d spacing of 15 Å at 200°C which collapsed to 9.6 Å at 400°C. The 14.6 Å peak of the Li-saturated smectite collapsed to 9.6 Å at 200°C while the 15 Å Ca-saturated smectite peak was stable up to 400°C. The unheated Al- and AlFe-pillared smectites adsorbed significantly more aflatoxin B1 from an aqueous suspension than did unpillared clay. In both water and simulated gastric fluid, heat treatment decreased aflatoxin B1 adsorption to pillared smectites, but heat treatment increased aflatoxin B1 adsorption to unpillared smectites. Without heat treatment, smectites saturated with divalent cations (Ca, Mg, Zn) adsorbed more aflatoxin B1 from an aqueous suspension than the smectite saturated with a monovalent cation (Li). Ca-saturated smectite showed the greatest aflatoxin B1 adsorption, 114 g kg–1, from aqueous suspension after 400°C heat treatment. The Zn-, Mg-, and Li-saturated smectites showed maximum aflatoxin adsorption of 107, 93, and 90 g kg–1, respectively, after 200°C heat treatment. From simulated gastric fluid with pepsin, the 200°C heated, Zn-saturated smectite had maximum aflatoxin B1 adsorption of 68 g kg–1. Pillared smectites effectively adsorbed aflatoxin B1 from aqueous suspension, but Ca- and Zn-saturated smectites after heat treatment might improve the selectivity of smectites for aflatoxin B1 over pepsin and enhance the efficacy of smectite as a feed additive.

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Effects of Metal-Polycation Pillaring and Exchangeable Cations on Aflatoxin Adsorption by Smectite

Khan

Akhtar

Akbar

et al. 2022

Clays and clay miner.

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Modifying a Smectite using Organic Nutrients to Enhance its Efficacy at Removing Aflatoxin B₁ from Corn Fermentation Solution

Alam

Deng

2022

Clays and clay miner.

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Aflatoxins in contaminated corn do not degrade in corn fermentation solution (CFS) during biofuel production; rather, they are enriched in the co-product, dried distillers grain. Aflatoxin B1 (AfB1) is the most toxic form of all aflatoxins. Removing AfB1 from CFS is desirable to minimize its toxicity to animals. Smectites can adsorb AfB1 from aqueous solutions and, therefore, inactivate the toxin, but proteins in CFS inhibit the adsorption of AfB1 by smectites. The current study aimed to minimize the interference by CFS in adsorption of AfB1 on smectite by modifying a calcium-smectite (Ca-3MS) with a small nutritive organic compound, e.g. carnitine, choline, arginine, histidine, or tryptophan. The organo-smectites were characterized by X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy, and adsorption of AfB1 in CFS by these composites was examined. Various degrees of intercalation of the organic nutrients into the smectites were observed with XRD and FTIR. After immersing the smectite and organo-smectites in the CFS, the d001 values of Ca-3MS expanded to ~1.82 nm due to protein interaction, but the organo-smectites were confined to ~1.39 nm, which indicated that the protein had limited access to the organo-smectite interlayers. The IR bands at ~1652, 1544, 1538, and 1454 cm–1 from the organo-smectites revealed, however, that complete protein inhibition was not achieved. The organo-smectites were capable of adsorbing AfB1 in simple aqueous solution with maximal adsorption capacity up to 0.55 mol kg–1. Significantly greater (p ≤ 0.05) AfB1 adsorption was achieved by choline- and carnitine-modified smectites compared with the original Ca-3MS in the presence of competing protein (pepsin) in simple aqueous solution. In real CFS, both AfB1 adsorption capacities (Qmax) and affinities (K) by all organo-smectites were greater (Qmax = up to 0.45 mol kg–1 and K = up to 0.165 μM–1) than those by Ca-3MS (Qmax = 0.22 mol kg–1 and K = 0.031 μM–1). The study suggested that using smectites modified with an organic nutritive compound could be an effective, economical, and safe strategy for removing mycotoxins, including aflatoxins, during biofuel production.

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Efficacy of Two Texas Bentonites in Binding Aflatoxin B1 and in Reducing Aflatoxicosis in Broilers

Velázquez

Kakani²,

Fowler³

et al. 2022

Clays and clay miner.

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The incorporation of bentonites in aflatoxin-contaminated animal feeds to remedy aflatoxicosis has been tested widely in animal trials. Yet, a large variation in efficacy among samples has been observed which has been attributed to variations in the properties of the clay mineral adsorbents. The objectives of the current study were: (1) to evaluate the mineral and chemical composition of two selected bentonites to find minerals or elements which are potentially of concern; (2) to characterize the aflatoxin B1 (AfB1) adsorption (selectivity, capacity, reversibility, and interlayer accessibility) by the bentonites; and (3) to evaluate the safety and efficacy of selected clays as amendments of aflatoxin-contaminated feed for broiler chickens. The mineral, chemical, and exchange cation composition of the clays were analyzed, and they appeared to be safe for use in feed. The bentonites and their fractions showed that adsorption capacities range from 0.48 to 0.97 mol/kg. The interlayer spaces of both montmorillonites were accessible by AfB1, and the adsorption was irreversible. Three-day old broiler chickens were given clean and high-aflatoxin-concentration (1400 mg/kg) diets with and without the presence of the two bentonites. After three weeks the chickens were sacrificed and biomarkers were evaluated. The presence of aflatoxins reduced the body weight by 58% and resulted in a 25% mortality rate. Adding bentonites 1TX and 4TX increased the body weight of the chickens by 14 and 23%, respectively, but did not improve the mortality rates. The results suggested that selected bentonites could effectively sequester aflatoxins in vivo but did not eliminate the total toxicity present in highly contaminated poultry feed.

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Reducing Competition of Pepsin in Aflatoxin Adsorption by Modifying a Smectite with Organic Nutrients

Cited by 9 publications

References 16 publications

Effects of Metal-Polycation Pillaring and Exchangeable Cations on Aflatoxin Adsorption by Smectite

Effects of Metal-Polycation Pillaring and Exchangeable Cations on Aflatoxin Adsorption by Smectite

Modifying a Smectite using Organic Nutrients to Enhance its Efficacy at Removing Aflatoxin B₁ from Corn Fermentation Solution

Efficacy of Two Texas Bentonites in Binding Aflatoxin B1 and in Reducing Aflatoxicosis in Broilers

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Reducing Competition of Pepsin in Aflatoxin Adsorption by Modifying a Smectite with Organic Nutrients

Cited by 9 publications

References 16 publications

Effects of Metal-Polycation Pillaring and Exchangeable Cations on Aflatoxin Adsorption by Smectite

Effects of Metal-Polycation Pillaring and Exchangeable Cations on Aflatoxin Adsorption by Smectite

Modifying a Smectite using Organic Nutrients to Enhance its Efficacy at Removing Aflatoxin B1 from Corn Fermentation Solution

Efficacy of Two Texas Bentonites in Binding Aflatoxin B1 and in Reducing Aflatoxicosis in Broilers

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Product

Resources

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Modifying a Smectite using Organic Nutrients to Enhance its Efficacy at Removing Aflatoxin B₁ from Corn Fermentation Solution