Aflatoxin production by Aspergillus flavus in rumen liquor and its implications

The Effects of Aflatoxin B1 Intake in Assaf Dairy Ewes on Aflatoxin M1 Excretion, Milk Yield, Haematology and Biochemical Profile

The aim of this study was to investigate the in vivo transfer of aflatoxin B1 (AFB1) to Assaf ewes' milk (aflatoxin M1, AFM1) and its effect on animal performance and health. Thirty Assaf ewes were allocated to three groups (C, L, H), and received a different individual daily dose of AFB1 (0, 40 and 80 μg) for 13 days. Milk (days 1, 2, 3, 4, 7, 14, 16 and 18) and blood (days 1, 7, 14 and 18) samples were collected. Milk yield, composition (except protein) and somatic cell counts (SCC) were not affected by AFB1 intake (p > 0.05). Haemoglobin concentration increased (p < 0.05) and haematocrit and alanine aminotransferase levels tended to increase (p < 0.10) in group H on day 14. AFM1 excretion was highly variable and detected in L and H animals from days 1 to 16 (3 days increase, 10 days steady-state, 3 days clearance). Carry-over rate (0.23%) was significantly higher in L (0.22-0.34%) than in H (0.16-0.19%) animals (p < 0.05). AFB1 daily doses of 40 to 80 µg do not impair milk yield; however, it may start affecting animals' health. Milk AFM1 depends mainly on the AFB1 intake whereas carryover rate is positively influenced by the level of milk production.

Association between aflatoxin M1 excretion in milk and indicators of rumen fermentation in bovines

Aflatoxins and its metabolites negatively impact the ruminant health and production. The present cross-sectional study was aimed to determine the effect of aflatoxins on rumen fermentation by deducing the correlation between the aflatoxin M1 (AFM1) excretion in milk and indicators of rumen fermentation in bovines. The indicators of rumen fermentation were taken into account and correlated with AFM1 concentration in milk of 120 bovines (cattle (n = 82) and buffalo (n = 38)). The AFM1 in milk samples (n = 120) was quantified by ELISA kit. The correlation analysis revealed that with increase in excretion of AFM1 in milk, the pH (r = 0.38), methylene blue reduction time (MBRT) (r = 0.43), sedimentation activity time (SAT) (r = 0.31) and ammonia nitrogen content (r = 0.34) of rumen liquor increase, whereas the total volatile fatty acid (TVFA) content (r =  - 0.25), total bacterial count (TBC) (r =  - 0.43) and total protozoal count (TPC) (r =  - 0.14) of rumen liquor decrease. The results of the present study suggest that the presence of aflatoxins in rumen could have negative effect on the process of rumen fermentation. Therefore, the prevention of primary entry point(s) of AFB1 through the feed of bovines is important for the animal health as well as public health.

Development of Gold Nanoparticles Decorated Molecularly Imprinted–Based Plasmonic Sensor for the Detection of Aflatoxin M1 in Milk Samples

Aflatoxins are a group of extremely toxic and carcinogenic substances generated by the mold of the genus Aspergillus that contaminate agricultural products. When dairy cows ingest aflatoxin B1 (AFB1)−contaminated feeds, it is metabolized and transformed in the liver into a carcinogenic major form of aflatoxin M1 (AFM1), which is eliminated through the milk. The detection of AFM1 in milk is very important to be able to guarantee food safety and quality. In recent years, sensors have emerged as a quick, low–cost, and reliable platform for the detection of aflatoxins. Plasmonic sensors with molecularly imprinted polymers (MIPs) can be interesting alternatives for the determination of AFM1. In this work, we designed a molecularly–imprinted–based plasmonic sensor to directly detect lower amounts of AFM1 in raw milk samples. For this purpose, we prepared gold–nanoparticle–(AuNP)−integrated polymer nanofilm on a gold plasmonic sensor chip coated with allyl mercaptan. N−methacryloyl−l−phenylalanine (MAPA) was chosen as a functional monomer. The MIP nanofilm was prepared using the light–initiated polymerization of MAPA and ethylene glycol dimethacrylate in the presence of AFM1 as a template molecule. The developed method enabled the detection of AFM1 with a detection limit of 0.4 pg/mL and demonstrated good linearity (0.0003 ng/mL–20.0 ng/mL) under optimized experimental conditions. The AFM1 determination was performed in random dairy farmer milk samples. Using the analogous mycotoxins, it was also demonstrated that the plasmonic sensor platforms were specific to the detection of AFM1.

Health risk from aflatoxins in processed meat products in Riyadh, KSA

This study investigated the health risks associated with aflatoxins (AFs) in processed meat products (PMP) sold in Riyadh, Kingdom of Saudi Arabia. The occurrence and levels of AFs were assessed using high-performance liquid chromatography with fluorescence detection (HPLC-FD), whereas the cancer risk attributed to the consumption of meat products containing AFs was estimated by means of margin of exposure (MOE) on a scale of 100-600, representing high and low exposure, respectively. The results indicated that 37.5% of the samples were contaminated, with concentrations ranging from 0.30 to 52.93 μg/kg, at an average of 6.4 ± 12.58 μg/kg. The percentage contamination levels with total AFs higher than the permissible Saudi limit of 20 μg/kg were 4% of samples analysed and 10% of contaminated samples. AFB1 and AFG1 were the most prevalent toxins, followed by AFB2; AFG2 was not detected in any sample. The MOE was found to be 175 and 311 for total AFs in processed beef meat and poultry meat products, respectively. These results showed that the daily intake of AF-contaminated PMP may constitute a public health concern. To our knowledge, this is the first study to report the health risk associated with PMP contaminated with AFs.

In-vitro evaluation of antimicrobial and insect repellent potential of supercritical-carbon dioxide (SCF-CO2) extracts of selected botanicals against stored product pests and foodborne pathogens

In the present study, the antimicrobial and the insect repellent activity of 16 botanical extracts obtained by supercritical CO₂ (SCF) extraction were evaluated. The present investigation was conducted as there is a necessity for exploration of natural botanical extracts that target both stored product insects and microbes. The antimicrobial activity was studied by disc diffusion and broth microdilution methods against ten microbial species, including Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis and Listeria monocytogenes), Gram-negative bacteria (Escherichia coli and Salmonella enterica), and fungi (Aspergillus flavus, Aspergillus paraciticus, Aspergillus ochraceous, Aspergillus niger and Penicillium verrucosum). Repellency assay was carried out by area preference method against three coleopteran insects (Tribolium castaneum, Rhyzopertha dominica and Sitophilus oryzae). Among all the extracts, thyme and ajwain were effective against all the tested bacteria with a minimum inhibition concentration (MIC) of 256-1024 µg/mL. Hop extract resulted in better antibacterial activity against all the tested Gram-positive bacteria with a MIC of 32-64 µg/mL. Oregano, thyme and ajwain extracts showed broad-spectrum antifungal activity against all the tested fungi with MIC of 128-1024 µg/mL. Most of the extracts exhibited class V (80.1-100%) repellency against T. castaneum. Extracts of hop, ajwain and thyme were found to have strong repellency against T. castaneum and R. dominica. Therefore, SCF extracts of ajwain and thyme can be explored further for the application of bio-extracts as a growth limiting factors in a microcosm where such consortia thrive.

Adverse Effects, Transformation and Channeling of Aflatoxins Into Food Raw Materials in Livestock

Aflatoxins are wide-spread harmful carcinogenic secondary metabolites produced by Aspergillus species, which cause serious feed and food contaminations and affect farm animals deleteriously with acute or chronic manifestations of mycotoxicoses. On farm, both pre-harvest and post-harvest strategies are applied to minimize the risk of aflatoxin contaminations in feeds. The great economic losses attributable to mycotoxin contaminations have initiated a plethora of research projects to develop new, effective technologies to prevent the highly toxic effects of these secondary metabolites on domestic animals and also to block the carry-over of these mycotoxins to humans through the food chain. Among other areas, this review summarizes the latest findings on the effects of silage production technologies and silage microbiota on aflatoxins, and it also discusses the current applications of probiotic organisms and microbial products in feeding technologies. After ingesting contaminated foodstuffs, aflatoxins are metabolized and biotransformed differently in various animals depending on their inherent and acquired physiological properties. These mycotoxins may cause primary aflatoxicoses with versatile, species-specific adverse effects, which are also dependent on the susceptibility of individual animals within a species, and will be a function of the dose and duration of aflatoxin exposures. The transfer of these undesired compounds from contaminated feed into food of animal origin and the aflatoxin residues present in foods become an additional risk to human health, leading to secondary aflatoxicoses. Considering the biological transformation of aflatoxins in livestock, this review summarizes (i) the metabolism of aflatoxins in different animal species, (ii) the deleterious effects of the mycotoxins and their derivatives on the animals, and (iii) the major risks to animal health in terms of the symptoms and consequences of acute or chronic aflatoxicoses, animal welfare and productivity. Furthermore, we traced the transformation and channeling of Aspergillus-derived mycotoxins into food raw materials, particularly in the case of aflatoxin contaminated milk, which represents the major route of human exposure among animal-derived foods. The early and reliable detection of aflatoxins in feed, forage and primary commodities is an increasingly important issue and, therefore, the newly developed, easy-to-use qualitative and quantitative aflatoxin analytical methods are also summarized in the review.

Sabotage at the Powerhouse? Unraveling the Molecular Target of 2-Isopropylbenzaldehyde Thiosemicarbazone, a Specific Inhibitor of Aflatoxin Biosynthesis and Sclerotia Development in Aspergillus flavus, Using Yeast as a Model System

Amongst the various approaches to contain aflatoxin contamination of feed and food commodities, the use of inhibitors of fungal growth and/or toxin biosynthesis is showing great promise for the implementation or the replacement of conventional pesticide-based strategies. Several inhibition mechanisms were found taking place at different levels in the biology of the aflatoxin-producing fungal species such as Aspergillus flavus: compounds that influence aflatoxin production may block the biosynthetic pathway through the direct control of genes belonging to the aflatoxin gene cluster, or interfere with one or more of the several steps involved in the aflatoxin metabolism upstream. Recent findings pointed to mitochondrial functionality as one of the potential targets of some aflatoxin inhibitors. Additionally, we have recently reported that the effect of a compound belonging to the class of thiosemicarbazones might be related to the energy generation/carbon flow and redox homeostasis control by the fungal cell. Here, we report our investigation about a putative molecular target of the 3-isopropylbenzaldehyde thiosemicarbazone (mHtcum), using the yeast Saccharomyces cerevisiae as model system, to demonstrate how the compound can actually interfere with the mitochondrial respiratory chain.

Purinergic signalling displays a pro-inflammatory profile in spleen and splenic lymphocytes of Rhamdia quelen fed with a diet contaminated by fungal mycotoxin: Involvement on disease pathogenesis

The spleen is an important secondary lymphatic organ that plays a key role in the immune and inflammatory responses of teleost fish. The purinergic signalling has been associated to these types of responses under pathological conditions by the regulation of extracellular adenosine triphosphate (ATP) and its metabolite adenosine (Ado), where both exert potent pro-inflammatory and anti-inflammatory profiles, respectively. The exact pathway involved on the immunotoxic effects of aflatoxin B₁ (AFB₁) in fish fed with diets containing this mycotoxin remains poorly understood. Thus, the aim of this study was to evaluate whether purinergic signalling exerts anti or pro-inflammatory effects in spleen and splenic lymphocytes of Rhamdia quelen fed with a diet contaminated by AFB₁. Ectonucleoside triphosphate diphosphohydrolase (NTPDase) activity (ATP as substrate) decreased in spleen and splenic lymphocytes of fish fed with an AFB₁-contaminated diet on day 21 post-feeding compared to fish fed with a basal diet; while adenosine deaminase (ADA) activity increased. No differences were observed between groups or over time regarding NTPDase (adenosine diphosphate as substrate) and 5'-nucleotidase activities. In summary, the purinergic signalling can be a pathway involved in the impairment of the immune and inflammatory responses in fish fed with an AFB₁-contaminated diet, contributing to the immunotoxic effects of AFB₁ in spleens of fish.

Xanthine oxidase activity exerts pro-oxidative and pro-inflammatory effects in serum of silver catfish fed with a diet contaminated with aflatoxin B1

Several studies have associated the involvement of xanthine oxidase (XO) activity, a source of uric acid and reactive oxygen species (ROS), to pro-oxidative and pro-inflammatory effects during pathological conditions. Considering this, the aim of this study was to evaluate whether upregulation on seric XO activity may be a pathway involved in the oxidative stress in fish exposed to a diet contaminated with aflatoxin B₁ (AFB₁ ), as well as whether it may be considered a pathway involved in ROS and NOx production. Xanthine oxidase activity, as well as the uric acid, ROS and NOx levels increased in serum of fish fed with a AFB₁ -contaminated diet on days 14 and 21 post-feeding compared to fish fed with a basal diet. Based on these evidences, upregulation of seric XO activity induces pro-oxidant and pro-inflammatory profiles in serum of fish fed with a AFB₁ -contaminated diet due to excessive formation on uric acid. Also, the excessive uric acid induces the release of pro-oxidant and pro-inflammatory mediators, as ROS and NOx, also contributing to oxidative and inflammatory profiles. In summary, the upregulation on seric XO activity may be considered a pathway involved in the oxidative stress of fish exposed to a diet contaminated with AFB₁ .

Risk assessment of exposure to aflatoxin B1 and ochratoxin A through consumption of different Pistachio (Pistacia vera L.) cultivars collected from four geographical regions of Iran

Iran is one of the main suppliers of pistachio for the European market accounting for over 90% of its demands; hence, efficient analytical methods are required for detection of mycotoxins contamination in pistachio kernels before exporting them. In this study, aflatoxin B1 (AFB1) and ochratoxin A (OTA) levels in five pistachio cultivars collected from four sites of Iran, were measured by HPLC. Based on the results, risk assessment for AFB1 and OTA residues was done. The highest mean concentrations of AFB1 and OTA were found in Ahmad-aghaei (4.33 and 2.19 ng/g, respectively) and Akbari (4.08 and 1.943 ng/g, respectively) cultivars from Rafsanjan, Iran. Even the highest concentrations of AFB1 and OTA in analyzed samples were lower than the corresponding maximum limits set by EU authorities. The hazard index (HI) value for consumers of Iranian pistachio is below one. It could be concluded that consumption of pistachio cultivated in these regions poses no health risk of mycotoxins exposure.