RESUMO
This study evaluated the efficacy of potentially probiotic fruit-derived Lactobacillus isolates, namely, L. paracasei 108, L. plantarum 49, and L. fermentum 111, to remove aflatoxin M1 (AFM1) from a phosphate buffer solution (PBS; spiked with 0.15 µg/mL AFM1). The efficacy of examined isolates (approximately 109 cfu/mL) as viable and non-viable cells (heat-killed; 100 °C, 1 h) to remove AFM1 was measured after 1 and 24 h at 37 °C. The recovery of AFM1 bound to bacterial cells after washing with PBS was also evaluated. Levels of AFM1 in PBS were measured with high-performance liquid chromatography. Viable and non-viable cells of all examined isolates were capable of removing AFM1 in PBS with removal percentage values in the range of 73.9-80.0% and 72.9-78.7%, respectively. Viable and non-viable cells of all examined Lactobacillus isolates had similar abilities to remove AFM1. Only L. paracasei 108 showed higher values of AFM1 removal after 24 h for both viable and non-viable cells. Percentage values of recovered AFM1 from viable and non-viable cells after washing were in the range of 13.4-60.6% and 10.9-47.9%, respectively. L. plantarum 49 showed the highest AFM1 retention capacity after washing. L. paracasei 108, L. plantarum 49, and L. fermentum 111 could have potential application to reduce AFM1 to safe levels in foods and feeds. The cell viability of examined isolates was not a pre-requisite for their capacity to remove and retain AFM1.
Assuntos
Aflatoxina M1/química , Lacticaseibacillus paracasei/fisiologia , Lactobacillus plantarum/fisiologia , Limosilactobacillus fermentum/fisiologia , Contaminação de Alimentos , Frutas/microbiologia , Viabilidade Microbiana , ProbióticosRESUMO
Since the high incidence of aflatoxin M1 (AFM1) in milk and dairy products poses a serious risk to human health, this work aimed to investigate the complex formation between bovine α-lactalbumin (α-La) and AFM1 using different spectroscopic methods coupled with molecular docking studies. Fluorescence spectroscopy measurements demonstrated the AFM1 addition considerably reduced the α-La fluorescence intensity through a static quenching mechanism. The results indicated on the endothermic character of the reaction, and the hydrophobic interaction played a major role in the binding between AFM1 and α-La. The binding site stoichiometric value (nâ¯=â¯1.32) and a binding constant of 2.12â¯×â¯103â¯M-1 were calculated according to the Stern-Volmer equation. The thermodynamic parameters ΔH, ΔS and ΔGb were determined at 93.58â¯kJâ¯mol-1, 0.378â¯kJâ¯mol-1â¯K-1 and -19.17⯱â¯0.96â¯kJâ¯mol-1, respectively. In addition, far-UV circular dichroism studies revealed alterations in the α-La secondary structures when the α-La-AFM1 complex was formed. An increased content of the α-helix structures (from 35 to 40%) and the ß-sheets (from 16 to 19%) were observed. Furthermore, protein-ligand docking modelling demonstrated AFM1 could bind to the hydrophobic regions of α-La protein. Overall, the gathered results confirmed the α-La-AFM1 complex formation.
Assuntos
Aflatoxina M1/química , Contaminação de Alimentos/análise , Lactalbumina/química , Animais , Sítios de Ligação , Bovinos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Leite/química , Simulação de Acoplamento Molecular , Estrutura Secundária de Proteína , Soroalbumina Bovina/química , TermodinâmicaRESUMO
Several strains of lactic acid bacteria (LAB), frequently used in food fermentation and preservation, have been reported to bind different types of toxins in liquid media. This study was carried out to investigate the effect of different concentrations of Lactobacillus rhamnosus GG (ATCC 53103) to bind aflatoxin M1 (AFM1) in liquid media. AFM1 binding was tested following repetitive washes or filtration procedures in combination with additional treatments such as heating, pipetting, and centrifugation. The mixture of L. rhamnosus GG and AFM1 was incubated for 18 h at 37 °C and the binding efficiency was determined by quantifying the unbound AFM1 using HPLC. The stability of the complexes viable bacteria-AFM1 and heat treated bacteria-AFM1 was tested. Depending on the bacterial concentration and procedure used, the percentages of bound AFM1 by L. rhamnosus GG varied from as low as undetectable to as high as 63%. The highest reduction in the level of unbound AFM1 was recorded for the five washes procedure that involved heating and pipetting. Results also showed that binding was partially reversible and AFM1 was released after repeated washes. These findings highlight the effect of different treatments on the binding of AFM1 to L. rhamnosus GG in liquid matrix.(AU)
Assuntos
Aflatoxina M1/análise , Aflatoxina M1/química , Lacticaseibacillus rhamnosus , Leite/microbiologiaRESUMO
ABSTRACT Several strains of lactic acid bacteria (LAB), frequently used in food fermentation and preservation, have been reported to bind different types of toxins in liquid media. This study was carried out to investigate the effect of different concentrations of Lactobacillus rhamnosus GG (ATCC 53103) to bind aflatoxin M1 (AFM1) in liquid media. AFM1 binding was tested following repetitive washes or filtration procedures in combination with additional treatments such as heating, pipetting, and centrifugation. The mixture of L. rhamnosus GG and AFM1 was incubated for 18 h at 37 °C and the binding efficiency was determined by quantifying the unbound AFM1 using HPLC. The stability of the complexes viable bacteria-AFM1 and heat treated bacteria-AFM1 was tested. Depending on the bacterial concentration and procedure used, the percentages of bound AFM1 by L. rhamnosus GG varied from as low as undetectable to as high as 63%. The highest reduction in the level of unbound AFM1 was recorded for the five washes procedure that involved heating and pipetting. Results also showed that binding was partially reversible and AFM1 was released after repeated washes. These findings highlight the effect of different treatments on the binding of AFM1 to L. rhamnosus GG in liquid matrix.
Assuntos
Animais , Aflatoxina M1/química , Lacticaseibacillus rhamnosus/química , Aflatoxina M1/metabolismo , Meios de Cultura/química , Lacticaseibacillus rhamnosus/metabolismoRESUMO
Several strains of lactic acid bacteria (LAB), frequently used in food fermentation and preservation, have been reported to bind different types of toxins in liquid media. This study was carried out to investigate the effect of different concentrations of Lactobacillus rhamnosus GG (ATCC 53103) to bind aflatoxin M1 (AFM1) in liquid media. AFM1 binding was tested following repetitive washes or filtration procedures in combination with additional treatments such as heating, pipetting, and centrifugation. The mixture of L. rhamnosus GG and AFM1 was incubated for 18h at 37°C and the binding efficiency was determined by quantifying the unbound AFM1 using HPLC. The stability of the complexes viable bacteria-AFM1 and heat treated bacteria-AFM1 was tested. Depending on the bacterial concentration and procedure used, the percentages of bound AFM1 by L. rhamnosus GG varied from as low as undetectable to as high as 63%. The highest reduction in the level of unbound AFM1 was recorded for the five washes procedure that involved heating and pipetting. Results also showed that binding was partially reversible and AFM1 was released after repeated washes. These findings highlight the effect of different treatments on the binding of AFM1 to L. rhamnosus GG in liquid matrix.
Assuntos
Aflatoxina M1/química , Lacticaseibacillus rhamnosus/química , Aflatoxina M1/metabolismo , Animais , Meios de Cultura/química , Lacticaseibacillus rhamnosus/metabolismoRESUMO
Chronic exposure to aflatoxins, and especially to aflatoxin B1 (AFB1), causes hepatocellular carcinoma with prevalence 16-32 times higher in developing compared with developed countries. Aflatoxin M1 (AFM1) is a monohydroxylated metabolite from AFB1 that is secreted in milk and which can be used as a biomarker of AFB1 exposure. This study aimed to determine AFM1 levels in human breast milk using immunoaffinity column clean-up with HPLC and fluorescence detection. Breast milk samples were obtained from 50 nursing mothers. Volunteers filled in a questionnaire giving their consent to analyse their samples as well as details of their socioeconomic, demographic and clinical data. The possible dietary sources of aflatoxins were assessed using a food frequency questionnaire. A total of 90% of the samples tested positive for AFM1, with a mean of 5.2 ng l(-1) and a range of 0.9-18.5 ng l(-1). The study demonstrated a high frequency of exposure of mothers and neonates to AFB1 and AFM1 in Colombia, and it points out the need to regulate and monitor continuously the presence of aflatoxins in human foods. Further research is needed in order to determine the presence of other mycotoxins in foods and in human samples as well as to devise protection strategies in a country where mycotoxins in human foods are commonly found.
Assuntos
Aflatoxina M1/química , Leite Humano/química , Adolescente , Adulto , Aflatoxina M1/metabolismo , Aflatoxinas/química , Biomarcadores , Cromatografia Líquida de Alta Pressão/métodos , Colômbia/epidemiologia , Exposição Ambiental , Feminino , Humanos , Lactente , Limite de Detecção , Reprodutibilidade dos TestesRESUMO
The aim was to carry out a survey of aflatoxin M(1) (AFM(1)) in raw whole milk from bulk tanks. The sample collection was performed in farms located in one the most important milk-production zones in the centre of Argentina. A total of 94 samples of milk from 47 dairy farms were analysed. AFM(1) analysis involved the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) with prior purification of the extracts using immunoaffinity columns. AFM(1) incidence in raw milk was high as 63.8% and levels were between not detected to 0.07 microg l(-1). Several contaminated samples (39%) were over the European Commission limit for infant milk (0.025 microg l(-1)), although none of samples were above Argentine legislation. Estimates of AFM(1) intake were assessed for different age populations. The average AFM(1) estimated daily intakes were 1.6, 0.5, 0.17 ng kg(-1) body weight day(-1) for 4-year-old babies, young children, and adults, respectively. All tested farms used pastures and silages at similar composition. Even though some farms (13) employed high-risk supplementary feeds, such as peanut pod and/or cotton seed, no statistically significant differences were observed between groups. Information from AFM(1) levels in milk in Argentina is limited. A systematic AFM(1) monitoring programme must be performed by means of accurate and reliable analytical techniques as a strategy for protecting milk consumers.