Aflatoxin M1 absorption by non-viable cells of lactic acid bacteria and Saccharomyces cerevisiae strains in Frescal cheese

A Comprehensive Systematic Review and Meta-Analysis on the Prevalence of Aflatoxin M1 in Dairy Products in Selected Middle East Countries

BACKGROUND

Human consumption of dairy products contaminated with aflatoxin (AF) M1 can lead to severe health issues. This AF's significance and impact on health necessitate a thorough investigation of its prevalence in dairy products.

OBJECTIVES

This study aims to determine the prevalence of AFM1 in dairy products through a systematic review and meta-analysis, focusing on data from Middle Eastern countries.

METHODS

We identified relevant studies through electronic database searches (PubMed, Scopus and Web of Science) up to August 2023. We employed a random-effects model to derive an overall estimate and used 95% confidence intervals to determine pooled prevalence rates.

RESULTS

The meta-analysis included 193 studies encompassing 297,530 samples of dairy products. The results showed that AFM1 contaminated 87% of dairy products. The following is a ranking of countries based on the prevalence of AFM1 in their dairy products: Iran > Jordan > Turkey > Kuwait > Lebanon > Syria > Egypt > Cyprus > the United Arab Emirates. The current meta-analysis indicated that Middle Eastern countries exhibited a high prevalence of AFM1 in dairy products. The prevalence rates for AFM1 in various dairy products were as follows: milk (87%), yogurt (68.9%), cheese (63.6%), kashk (62.9%), doogh (55.6%) and ice cream (54%). Pasteurized milk (99.5%), ultra-high temperature (91.3%), raw milk (73%) and traditional milk (51%), among other milk types, had the highest contamination rates.

CONCLUSION

The study reveals a high prevalence of AFM1 in dairy products, particularly in Middle Eastern countries. Given the critical importance of milk and dairy products in the diet, special measures are needed to safeguard their quality and protect consumers from AF contamination.

Evaluation of Ability of Inactivated Biomasses of Lacticaseibacillus rhamnosus and Saccharomyces cerevisiae to Adsorb Aflatoxin B1 In Vitro

Biological decontamination strategies using microorganisms to adsorb aflatoxins have shown promising results for reducing the dietary exposure to these contaminants. In this study, the ability of inactivated biomasses of Lacticaseibacillus rhamnosus (LRB) and Saccharomyces cerevisiae (SCB) incorporated alone or in combination into functional yogurts (FY) at 0.5-4.0% (w/w) to adsorb aflatoxin B1 (AFB1) was evaluated in vitro. Higher adsorption percentages (86.9-91.2%) were observed in FY containing 1.0% LR + SC or 2.0% SC (w/w). The survival of mouse embryonic fibroblasts increased after exposure to yogurts containing LC + SC at 1.0-4.0% (w/w). No significant differences were noted in the physicochemical and sensory characteristics between aflatoxin-free FY and control yogurts (no biomass) after 30 days of storage. The incorporation of combined LRB and SCB into yogurts as vehicles for these inactivated biomasses is a promising alternative for reducing the exposure to dietary AFB1. The results of this trial support further studies to develop practical applications aiming at the scalability of using the biomasses evaluated in functional foods to mitigate aflatoxin exposure.

Aflatoxin Biodetoxification Strategies Based on Postbiotics

Aflatoxins (AFs) are secondary metabolites produced by fungi, and they are deemed the most perilous mycotoxin and food safety predicament. The exposure of humans to mycotoxins transpires either directly through the consumption of contaminated agricultural commodities or indirectly through the ingestion of items derived from animals that have been nourished with tainted substances of animal origin. To ensure the detoxification of AFs in animal and plant food products and to mitigate the risks they pose to public health and the economy, diverse techniques (physical, chemical, and biological) have been subject to scrutiny. By altering and eradicating the molecular structure of the toxin, all of these approaches impede its transmission to the digestive system and potentially diminish the accessibility of toxins to the target tissue, ultimately eliminating them. Given the pervasive predicaments attributed to the contamination of foods and feeds by AFs, it is of utmost importance to urgently devise cost-effective and appropriate strategies to combat this hazard. This review highlights the concept of AFs, definitions, and benefits of postbiotics and their biological role in the detoxification of AFs, as well as their benefits in the food-pharmaceutical industry.

Adsorptive removal of aflatoxin B1 via spore protein from Aspergillus luchuensis YZ-1

Aflatoxin B1 (AFB1) is the most toxic mycotoxin commonly found in the environment. Finding efficient and environmentally friendly ways to remove AFB1 is critical. In this study, Aspergillus luchuensis YZ-1 demonstrated a potent ability to adsorb AFB1 for the first time, and the binding of AFB1 to YZ-1 is highly stable. Spores exhibited higher adsorption efficiency than mycelia, adsorbing approximately 95 % of AFB1 within 15 min. The spores were comprehensively characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy. Various adsorption kinetic models (pseudo-first and pseudo-second order), adsorption isotherm models (Freundlich and Langmuir), Fourier transform infrared, and X-ray photoelectron spectroscopy were used to investigate the adsorption properties and mechanisms. The adsorption capacity of spores decreased with heating, urea, and SDS treatments, indicating that spore proteins may be the primary substance for AFB1 adsorption. Subsequent experiments showed that proteins with molecular weights greater than 50 kDa played a key role in the adsorption. Additionally, the spores possess excellent storage properties and are valuable for adsorbing AFB1 from vegetable oils. Therefore, the YZ-1 spores hold promise for development into a novel biosorbent for AFB1 removal.

Lactic acid bacteria as an eco-friendly approach in plant production: Current state and prospects

Since the late nineteenth century, the agricultural sector has experienced a tremendous increase in chemical use in response to the growing population. Consequently, the intensive and indiscriminate use of these substances caused serious damage on several levels, including threatening human health, disrupting soil microbiota, affecting wildlife ecosystems, and causing groundwater pollution. As a solution, the application of microbial-based products presents an interesting and ecological restoration tool. The use of Plant Growth-Promoting Microbes (PGPM) affected positive production, by increasing its efficiency, reducing production costs, environmental pollution, and chemical use. Among these microbial communities, lactic acid bacteria (LAB) are considered an interesting candidate to be formulated and applied as effective microbes. Indeed, these bacteria are approved by the European Food Safety Authority (EFSA) and Food and Drug Administration (FDA) as Qualified Presumption of Safety statute and Generally Recognized as Safe for various applications. To do so, this review comes as a road map for future research, which addresses the different steps included in LAB formulation as biocontrol, bioremediation, or plant growth promoting agents from the isolation process to their field application passing by the different identification methods and their various uses. The plant application methods as well as challenges limiting their use in agriculture are also discussed.

Chitosan nanoparticle encapsulation increased the prophylactic efficacy of Lactobacillus plantarum RM1 against AFM1-induced hepatorenal toxicity in rats

Aflatoxin M1 (AFM1) is a significant contaminant of food, particularly dairy products and can resist various industrial processes. Several probiotic strains like Lactobacillus plantarum are known to reduce aflatoxin availability in synthetic media and some food products. The current work investigated the possible chitosan coating prophylactic efficacy of Lactobacillus plantarum RM1 nanoemulsion (CS-RM1) against AFM1-induced hepatorenal toxicity in rats. Twenty-eight male Wistar rats were divided into four groups (n = 7) as follows: group 1 received normal saline, group 2 received CS-RM1 (1mL contains 6.7 × 1010 CFU), group 3 received AFM1 (60 µg/kg bwt), and group 4 received both CS-RM1(1 mL contains 6.7 × 1010 CFU) and AFM1 (60 µg/kg bwt). All receiving materials were given to rats daily via oral gavage for 28 days. AFM1 caused a significant elevation in serum levels of ALT, AST, ALP, uric acid, urea, and creatinine with marked alterations in protein and lipid profiles. Additionally, AFM1 caused marked pathological changes in the liver and kidneys, such as cellular necrosis, vascular congestion, and interstitial inflammation. AFM1 also increased the MDA levels and decreased several enzymatic and non-enzymatic antioxidants. Liver and kidney sections of the AFM1 group displayed strong caspase-3, TNF-α, and iNOS immunopositivity. Co-treatment of CS-RM1 with AFM1 significantly lowered the investigated toxicological parameter changes and markedly improved the microscopic appearance of liver and kidneys. In conclusion, AFM1 induces hepatorenal oxidative stress damage via ROS overgeneration, which induces mitochondrial caspase-3-dependent apoptosis and inflammation. Furthermore, CS-RM1 can reduce AFM1 toxicity in both the liver and kidneys. The study recommends adding CS-RM1 to milk and milk products for AFM1-elimination.

Is chemical analysis suitable for detecting mycotoxins in agricultural commodities and foodstuffs?

The assessment of the risks of mycotoxins to humans through consuming contaminated foods resulted in specific legislation that evaluates the presence, quantities, and type of mycotoxins in agricultural commodities and foodstuffs. Thus, to ensure compliance with legislation, food safety and consumer health, the development of suitable analytical procedures for identifying and quantifying mycotoxins in the free or modified form, in low-concentration and in complex samples is necessary. This review reports the application of the modern chemical methods of analysis employed in mycotoxin detection in agricultural commodities and foodstuffs. It is reported extraction methods with reasonable accuracy and those present characteristics according to guidelines of Green Analytical Chemistry. Recent trends in mycotoxins detection using analytical techniques are presented and discussed, evaluating the robustness, precision, accuracy, sensitivity, and selectivity in the detection of different classes of mycotoxins. Sensitivity coming from modern chromatographic techniques allows the detection of very low concentrations of mycotoxins in complex samples. However, it is essential the development of more green, fast and more suitable accuracy extraction methods for mycotoxins, which agricultural commodities producers could use. Despite the high number of research reporting the use of chemically modified voltammetric sensors, mycotoxins detection still has limitations due to the low selectivity from similar chemical structures of mycotoxins. Furthermore, spectroscopic techniques are rarely employed due to the limited number of reference standards for calibration procedures.

Green removal of unpleasant volatiles from soapberry (Sapindus mukorossi) extracts by two-phase microbial fermentation fortified with pomelo peel waste

Soapberry (Sapindus mukorossi Gaertn) is a popular woody plant in Vietnam, often used as a cleaning product due to its ability to wash, foam and emulsify due to high saponin content. In this study, the performance of fermentation by two microbial strains, namely Saccharomyces cerevisiae active dry yeast (ADY) and Levilactobacillus brevis lactic acid bacteria (LB) along with the addition of pomelo peel (flavedo) was evaluated during 15 days in terms of sugar removal, antioxidant and antibacterial activities, foaming power, volatile composition, and sensory acceptability. The results showed that the soluble solid content of original extracts experienced a significant decrease from 14.5% to a stable range of 9.4-11.0% until day 15 for all fermented samples, which correlated with a reduction by approximately 60% in reducing sugars (from 12.52 g L-1 to 4.77-6.56 g L-1). In addition, the saponin content of fermented extracts was in the range of 118.2-145.0 mg L-1 while antioxidant activities were extremely reduced after 15 days of fermentation. Increases in pomelo peel imparted fermented extracts with greater antibacterial activity against Staphylococcus aureus ATCC 6538, Proteus mirabilis ATCC 25933, and Candida albicans ATCC 10231, and LB had higher activity than ADY overall. Regarding the volatile profiles, two main compounds in the original extracts, including trilaurin (75.02%) and 1-dodecanoyl-3-myristoyl glycerol (24.85%), were completely removed and replaced by new alkanes, alkenes, alcohols, esters, and organic acids, and particularly d-limonene (86.34-95.31%) upon pomelo addition. Additionally, the foaming ability and stability of fermented extracts were also enhanced and there was clear distinction between fermented and unfermented samples using principal component analysis based on sensory liking data which showed consumers' preference towards fermented samples with a high percentage of pomelo peel.

Role of Dead Cells in Collective Stress Tolerance in Microbial Communities: Evidence from Yeast

A substantial part of yeast life cycle takes place in the communities where the cells are surrounded by their own clones. Meanwhile, yeast cell fitness depends not only on its own adaptations but also on the processes in the neighboring cells. Moreover, even if a cell loses its clonogenic ability, it is still capable of protecting surrounding cells that are still alive. Dead cells can absorb lipophilic antibiotics and provide nutrients to their kin neighbors. Some enzymes can be released into the environment and detoxify exogenous toxins. For example, cytosolic catalase, which degrades hydrogen peroxide, can stay active outside of the cell. Inviable cells of pathogenic yeast species can suppress host immune responses and, in this way, boost spread of the pathogen. In this review, we speculate that biochemical processes in dying cells can facilitate increase of stress resistance in the alive kin cells and therefore be a subject of natural selection. We considered possible scenarios of how dead microbial cells can increase survival of their kin using unicellular fungi - baker's yeast Saccharomyces cerevisiae - as an example. We conclude that the evolutionary conserved mechanisms of programmed cell death in yeast are likely to include a module of early permeabilization of the cell plasma membrane rather than preserve its integrity.

Probiotics as a biological detoxification tool of food chemical contamination: A review

Nowadays, people are exposed to diverse environmental and chemical pollutants produced by industry and agriculture. Food contaminations such as persistent organic pollutants (POPs), heavy metals, and mycotoxins are a serious concern for global food safety with economic and public health implications especially in the newly industrialized countries (NIC). Mounting evidence indicates that chronic exposure to food contaminants referred to as xenobiotics exert a negative effect on human health such as inflammation, oxidative stress, and intestinal disorders linked with perturbation of the composition and metabolic profile of the gut microflora. Although the physicochemical technologies for food decontamination are utilized in many cases but require adequate conditions which are often not feasible to be met in many industrial sectors. At present, one promising approach to reduce the risk related to the presence of xenobiotics in foodstuffs is a biological detoxification done by probiotic strains and their enzymes. Many studies confirmed that probiotics are an effective, feasible, and inexpensive tool for preventing xenobiotic-induced dysbiosis and alleviating their toxicity. This review aims to summarize the current knowledge of the direct mechanisms by which probiotics can influence the detoxification of xenobiotics. Moreover, probiotic-xenobiotic interactions with the gut microbiota and the host response were also discussed.

Effect of Lactic Acid Bacteria Strains on the Growth and Aflatoxin Production Potential of Aspergillus parasiticus, and Their Ability to Bind Aflatoxin B1, Ochratoxin A, and Zearalenone in vitro

The increased consumption of plant-based foods has intensified the concern related to mycotoxin intoxication. This study aimed to investigate the effect of selected lactic acid bacteria (LAB) strains on the growth of Aspergillus parasiticus NRRL 2999 and its production of aflatoxin (AF). The ability of the heat-killed (100°C for 1 h) LAB strains to bind aflatoxin M1 (AFM1) in milk and aflatoxin B1 (AFB1), ochratoxin A (OTA), and zearalenone (ZEN) in potassium phosphate buffer (PPB) was also evaluated in vitro. Ten LAB strains were tested individually, by inoculating them simultaneously with the fungus or after incubation of the fungus for 24 or 48 h at 25°C. Double layer yeast extract sucrose (YES) agar, de Man Rogosa and Sharpe (MRS) agar, and YES broth were incubated for 7 days at 25°C to follow the development of the fungus. Levilactobacillus spp. 3QB398 and Levilactobacillus brevis 2QB422 strains were able to delay the growth of A. parasiticus in YES broth, even when these strains were inoculated 24 h after the fungus. The inhibitory effect of these LAB strains was confirmed by the reduction of fungus colony size, suggesting dominance of LAB by competition (a Lotka-Voltera effect). The production of AFB1 by A. parasiticus was inhibited when the fungus was inoculated simultaneously with Lactiplantibacillus plantarum 3QB361 or L. plantarum 3QB350. No AFB1 was found when Levilactobacillus spp. 2QB383 was present, even when the LAB was inoculated 48 h after the fungus. In binding studies, seven inactivated LAB strains were able to promote a reduction of at least 50% the level of AFB1, OTA, and ZEN. This reduction varied depending on the pH of the PPB. In milk, however, only two inactivated LAB strains were able to reduce AFM1, with a reduction of 33 and 45% for Levilactobacillus spp. 3QB398 (Levilactobacillus spp.) and L. brevis 2QB422, respectively. Nevertheless, these results clearly indicate the potential of using LAB for mycotoxin reduction.

Fates of aflatoxin B1 from wheat flour to Iranian traditional cookies: Managing procedures to aflatoxin B1 reduction during traditional processing

Aflatoxin B1 (AFB1) incidence in cereal, especially in wheat products, is a serious worldwide challenge for human health. The objective of the current study was to survey the effect of various factors, including fermentation times, yeast levels, ingredients, and time/temperature combinations of the baking process on aflatoxin B1 (AFB1) reduction in order to modify parameters of the traditional cookie-making process. AFB1 levels were analyzed by an HPLC-fluorescence detector. The results revealed AFB1 levels significantly decreased during fermentation (%23.7), depending on an increase in the yeast level (2%) and fermentation time (90 min). Furthermore, there was a significant correlation between pH reduction and AFB1 decomposition. However, the formulation of the recipe did not show a significant effect on the detoxification of AFB1. The baking temperature increase in an admissible technological range (280°C for 15 min) more effectively reduced AFB1 content (%53.9). As a result, the exact control of the traditional process was able to significantly decreased AFB1 content as a serious health-threatening toxin in the final product (%75.9). However, AFB1 toxicity reduction should be considered seriously in the raw materials and such products.