Potential of lactic acid bacteria in aflatoxin risk mitigation

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.

Rice Weevil (Sitophilus oryzae L.) Gut Bacteria Inhibit Growth of Aspergillus flavus and Degrade Aflatoxin B1

In this study, bacteria residing in the gut of the rice weevils (Sitophilus oryzae L.) (Coleoptera: Curculionidae) feeding on aflatoxin-contaminated corn kernels were isolated and evaluated for their ability to suppress Aspergillus flavus and to remove/degrade aflatoxin B1 (AFB1). Four morphologically distinct S. oryzae gut-associated bacterial isolates were isolated and identified as Bacillus subtilis (RWGB1), Bacillus oceanisediminis (RWGB2), Bacillus firmus (RWGB3), and Pseudomonas aeruginosa (RWGB4) based on 16S rRNA gene sequence analysis. These bacterial isolates inhibited A. flavus growth in the dual culture assay and induced morphological deformities in the fungal hyphae, as confirmed by scanning electron microscopy. All four bacterial isolates were capable of removing AFB1 from the nutrient broth medium. In addition, culture supernatants of these bacterial isolates degraded AFB1, and the degradation of toxin molecules was confirmed by liquid chromatography-mass spectrometry. The bacterial isolates, B. subtilis RWGB1, B. oceanisediminis RWGB2, and P. aeruginosa RWGB4, were capable of producing antifungal volatile organic compounds that inhibited A. flavus growth. These results suggest that the bacterial isolates from S. oryzae gut have the potential to bind and/or degrade AFB1. Further research on their application in the food and feed industries could enhance the safety of food and feed production.

The Role of Probiotics in Improving Food Safety: Inactivation of Pathogens and Biological Toxins

Currently, many advances have been made in avoiding food contamination by numerous pathogenic and toxigenic microorganisms. Many studies have shown that different probiotics, in addition to having beneficial effects on the host's health, have a very good ability to eliminate and neutralize pathogens and their toxins in foods which leads to enhanced food safety. The present review purposes to comprehensively discuss the role of probiotics in improving food safety by inactivating pathogens (bacterial, fungal, viral, and parasite agents) and neutralizing their toxins in food products. Some recent examples in terms of the anti-microbial activities of probiotics in the body after consuming contaminated food have also been mentioned. This review shows that different probiotics have the potential to inactivate pathogens and neutralize and detoxify various biological agents in foods, as well as in the host body after consumption.

Research advances in the degradation of aflatoxin by lactic acid bacteria

Aflatoxins are toxic secondary metabolites that often contaminate food and animal feed, causing huge economic losses and serious health hazards. Aflatoxin contamination has become a major concern worldwide. Biological methods have been used to reduce aflatoxins in food and feed by inhibiting toxin production and detoxification. Among biological methods, lactic acid bacteria are of significant interest because of their safety, efficiency, and environmental friendliness. This study aimed to review the mechanisms by which lactic acid bacteria degrade aflatoxins and the factors that influence their degradation efficiency, including the action of the lactic acid bacteria themselves (cell wall adsorption) and the antifungal metabolites produced by the lactic acid bacteria. The current applications of lactic acid bacteria to food and feed were also reviewed. This comprehensive analysis provided insight into the binding mechanisms between lactic acid bacteria and aflatoxins, facilitating the practical applications of lactic acid bacteria to food and agriculture.

Aflatoxins posing threat to food safety and security in Pakistan: Call for a one health approach

Aflatoxins are among the most important mycotoxins due to their widespread occurrence and adverse impacts on humans and animals. These toxins and/or their metabolites cannot be destroyed with cooking or boiling methods. Therefore, consumption of aflatoxin-contaminated food may lead to impaired growth, compromised immunity, stomach and liver cancer, and acute toxicity. These adverse effects along with food wastage might have detrimental consequences on a country's economy. Several studies from Pakistan reported a high prevalence of aflatoxins in food and feed commodities (Range; milk = 0.6-99.4%, cereals, and grains = 0.38-41%, animal feed = 31-100%). Notably, Pakistan reported very high figures of impaired child growth-stunted 40.2%, wasted 17.7% and underweight 28.9%-that could be associated with the higher aflatoxin prevalence in food items. Importantly, high aflatoxins prevalence, i.e. 100%, 69% and 60.5%, in children has been reported in Pakistan. Food and feed are more prone to aflatoxin contamination due to Pakistan's hot and humid climate; however, limited awareness, inadequate policy framework, and weak implementation mechanisms are the major obstacles to effective control. This review will discuss aflatoxins prevalence, associated risk factors, adverse health effects, required regulatory regime, and effective control strategies adopting the One Health approach to ensure food safety and security.

Neoteric Biofilms Applied to Enhance the Safety Characteristics of Ras Cheese during Ripening

The milk's natural flora, or the starter, can preserve cheesemaking and allow for microbial competition. This investigation aimed to improve cheese safety and assess its characteristics using probiotic cell pellets (LCP) or cell-free extracts (CFS). Cheese samples were collected from different areas to investigate the current contamination situation. Six CFSs of probiotics were assessed as antifungal against toxigenic fungi using liquid and solid media and their aflatoxin reduction impact. The most effective CFS was chosen for cheese coating in nanoemulsion. Coated cheese with CFS, LCP, and LCP-CFS was assessed against control for changes in chemical composition, ripening indications, rheological properties, and microbiology. Results showed significant contamination levels in the collected samples, and toxic fungi were present. Lactobacillus rhamnosus CFS has aflatoxins reducibility in liquid media. During cheese ripening, uncoated cheese showed higher fat, protein, salt content, soluble nitrogen, total volatile fatty acids, tyrosine, and tryptophan contents than coated samples, except for LCP-coating treatment. Cheese rheology indicated that coating treatments had the lowest hardness, cohesiveness, gumminess, chewiness, and springiness compared to uncoated cheese. Uncoated cheese had the highest yeast and mold counts compared to the treated ones. The LCP-CFS-coated cheese showed no Aspergillus cells for up to 40 days. Uncoated Ras cheese recorded slightly lower flavor, body, texture, and appearance scores than coated cheeses. In conclusion, coating cheese with L. rhamnosus nanoemulsion has antifungal and antiaflatoxigenic properties, even for LCP, CFS, and CFS-LCP, which could extend cheese shelf life.

TGF-β pathways in aging and immunity: lessons from Caenorhabditis elegans

The Transforming Growth Factor-β (TGF-β) superfamily of signaling molecules plays critical roles in development, differentiation, homeostasis, and disease. Due to the conservation of these ligands and their signaling pathways, genetic studies in invertebrate systems including the nematode Caenorhabditis elegans have been instrumental in identifying signaling mechanisms. C. elegans is also a premier organism for research in longevity and healthy aging. Here we summarize current knowledge on the roles of TGF-β signaling in aging and immunity.

Natural mycotoxin contamination in dog food: A review on toxicity and detoxification methods

Nowadays, the companion animals (dogs or other pets) are considered as members of the family and have established strong emotional relationships with their owners. Dogs are long lived compared to food animals, so safety, adequacy, and efficacy of dog food is of great importance for their health. Cereals, cereal by-products as well as feedstuffs of plant origin are commonly employed food resources in dry food, yet are potential ingredients for mycotoxins contamination, so dogs are theoretically more vulnerable to exposure when consumed daily. Aflatoxins (AF), deoxynivalenol (DON), fumonisins (FUM), ochratoxin A (OTA), and zearalenone (ZEA) are the most frequent mycotoxins that might present in dog food and cause toxicity on the growth and metabolism of dogs. An understanding of toxicological effects and detoxification methods (physical, chemical, or biological approaches) of mycotoxins will help to improve commercial ped food quality, reduce harm and minimize exposure to dogs. Herein, we outline a description of mycotoxins detected in dog food, toxicity and clinical findings in dogs, as well as methods applied in mycotoxins detoxification. This review aims to provide a reference for future studies involved in the evaluation of the risk, preventative strategies, and clear criteria of mycotoxins for minimizing exposure, reducing harm, and preventing mycotoxicosis in dog.

Gut-Faecal Microbial and Health-Marker Response to Dietary Fumonisins in Weaned Pigs

This study investigated effects of dietary fumonisins (FBs) on gut and faecal microbiota of weaned pigs. In total, 18 7-week-old male pigs were fed either 0, 15 or 30 mg FBs (FB₁ + FB₂ + FB₃)/kg diet for 21 days. The microbiota was analysed with amplicon sequencing of the 16S rRNA gene V3-V4 regions (Illumina MiSeq). Results showed no treatment effect (p > 0.05) on growth performance, serum reduced glutathione, glutathione peroxidase and malondialdehyde. FBs increased serum aspartate transaminase, gamma glutamyl-transferase and alkaline phosphatase activities. A 30 mg/kg FBs treatment shifted microbial population in the duodenum and ileum to lower levels (compared to control (p < 0.05)) of the families Campylobacteraceae and Clostridiaceae, respectively, as well as the genera Alloprevotella, Campylobacter and Lachnospiraceae Incertae Sedis (duodenum), Turicibacter (jejunum), and Clostridium sensu stricto 1 (ileum). Faecal microbiota had higher levels of the Erysipelotrichaceae and Ruminococcaceae families and Solobacterium, Faecalibacterium, Anaerofilum, Ruminococcus, Subdoligranulum, Pseudobutyrivibrio, Coprococcus and Roseburia genera in the 30 mg/kg FBs compared to control and/or to the 15 mg/kg FBs diets. Lactobacillus was more abundant in the duodenum compared to faeces in all treatment groups (p < 0.01). Overall, the 30 mg/kg FBs diet altered the pig gut microbiota without suppressing animal growth performance.

Biodegradation of Aflatoxin B1 in the Baijiu Brewing Process by Bacillus cereus

Aflatoxin is a potent mycotoxin and a common source of grain contamination that leads to great economic losses and health problems. Although distilled baijiu cannot be contaminated by aflatoxin, its presence in the brewing process affects the physiological activities of micro-organisms and reduces product quality. Bacillus cereus XSWW9 capable of degrading aflatoxin B1 (AFB1) was isolated from daqu using coumarin as the sole carbon source. XSWW9 degraded 86.7% of 1 mg/L AFB1 after incubation at 37 °C for 72 h and tolerated up to 1 mg/L AFB1 with no inhibitory effects. Enzymes in the cell-free supernatant of XSSW9 played a significant role in AFB1 degradation. The AFB1-degradation activity was sensitive to protease K and SDS treatment, which indicated that extracellular proteins were responsible for the degradation of AFB1. In order to investigate the AFB1-degradation ability of XSSW9 during the baijiu brewing process, AFB1 and XSWW9 were added to grain fermentation (FG-T) and normal grain fermentation without AFB1, while normal grain fermentation without AFB1 and XSWW9 was used as a control (FG-C). At the end of the fermentation, 99% AFB1 was degraded in the residue of fermented grains. The differences of microbial communities in the fermented grains showed that there were no significant differences between FG-T and FG-C in the relative abundance of dominant genera. The analysis of volatile compounds of their distillation showed that the contents of skeleton flavor components was similar between FG-T and FG-C. These results offer a basis for the development of effective strategies to reduce the effect of AFB1 on the brewing process and ensure that the production of baijiu is stable.

Mycotoxins in soybean-based foods fermented with filamentous fungi: Occurrence and preventive strategies

Fermented soybean products are widely consumed worldwide, and their popularity is increasing. Filamentous fungi, such as Actinomucor, Aspergillus, Monascus, Mucor, Penicillium, Rhizopus, and Zymomonas, play critical roles in the fermentation processes of many soybean foods. However, besides producing essential enzymes for food fermentation, filamentous fungi can release undesirable or even toxic metabolites into the food. Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi and may be detected during the food production process. Without effective prevention strategies, mycotoxin contamination in fermented soybean products poses a risk to human health. This review focused on the changes in mycotoxigenic fungal abundance and mycotoxin contamination at different stages during the production of soybean-based fermented foods, as well as effective strategies for preventing mycotoxin contamination in such products. Data from relevant studies demonstrated a tendency of change in the genera of mycotoxigenic fungi and types of mycotoxins (aflatoxins, alternariol, alternariol monomethyl ether, deoxynivalenol, fumonisins, ochratoxin A, rhizoxins, T-2 toxin, and zearalenone) present in the raw materials and the middle and final products. The applicability of traditional chemical and physical mitigation strategies and novel eco-friendly biocontrol approaches to prevent mycotoxin contamination in soybean-based fermented foods were discussed. The present review highlights the risks of mycotoxin contamination during the production of fermented soybean products and recommends promising strategies for eliminating mycotoxin contamination risk in soybean-based fermented foods.

Recent Progress on Techniques in the Detection of Aflatoxin B1 in Edible Oil: A Mini Review

Contamination of agricultural products and foods by aflatoxin B1 (AFB1) is becoming a serious global problem, and the presence of AFB1 in edible oil is frequent and has become inevitable, especially in underdeveloped countries and regions. As AFB1 results from a possible degradation of aflatoxins and the interaction of the resulting toxic compound with food components, it could cause chronic disease or severe cancers, increasing morbidity and mortality. Therefore, rapid and reliable detection methods are essential for checking AFB1 occurrence in foodstuffs to ensure food safety. Recently, new biosensor technologies have become a research hotspot due to their characteristics of speed and accuracy. This review describes various technologies such as chromatographic and spectroscopic techniques, ELISA techniques, and biosensing techniques, along with their advantages and weaknesses, for AFB1 control in edible oil and provides new insight into AFB1 detection for future work. Although compared with other technologies, biosensor technology involves the cross integration of multiple technologies, such as spectral technology and new nano materials, and has great potential, some challenges regarding their stability, cost, etc., need further studies.

The importance and mitigation of mycotoxins and plant toxins in Southeast Asian fermented foods

Fermented foods (ffs) and beverages are widely consumed in Southeast Asia (SEA) for their nutritional balance, flavor, and food security. They serve as vehicles for beneficial microorganisms performing a significant role in human health. However, there are still major challenges concerning the safety of ffs and beverages due to the presence of natural toxins. In this review, the common toxins found in traditional ffs in SEA are discussed with special reference to mycotoxins and plant toxins. Also, mitigation measures for preventing risks associated with their consumption are outlined. Ochratoxin, citrinin, aflatoxins were reported to be major mycotoxins present in SEA ffs. In addition, soybean-based ff food products were more vulnerable to mycotoxin contaminations. Common plant toxins recorded in ffs include cyanogenic glycosides, oxalates, phytates and saponins. Combined management strategies such as pre-harvest, harvest and post-harvest control and decontamination, through the integration of different control methods such as the use of clean seeds, biological control methods, fermentation, appropriate packaging systems, and controlled processing conditions are needed for the safe consumption of indigenous ffs in SEA.

Lactic Acid Bacteria as Potential Biocontrol Agents for Fusarium Head Blight Disease of Spring Barley

Fusarium head blight (FHB) is a devastating disease encountered by spring-grown barley. Traditionally, synthetic chemicals have been used to control this disease on small grain cereals. A move toward biological control agents as part of sustainable agriculture is pertinent due to the evolutionary mechanisms employed by fungal diseases to circumvent current protection strategies. This study evaluated the effect of six lactic acid bacteria isolates on the development of FHB under in vitro and glasshouse conditions. The relative expression of Fusarium marker genes and transcription factors under Fusarium infection was examined. Dual-culture assays observed inhibition zones of up to 10 and 17% of total plate area for L. amylovorus FST 2.11 and L. brevis R2Δ, respectively. Detached leaf assays validated the antifungal activity and showed the potential of all test isolates to significantly inhibit sporulation of Fusarium culmorum and Fusarium graminearum strains. Spray inoculation of lactic acid bacteria to barley spikelets prior to Fusarium spore application significantly reduced disease severity for five candidates (P < 0.05) under glasshouse conditions. Mycotoxin analysis revealed the ability of L. amylovorus DSM20552 to significantly reduce deoxynivalenol content in spikelets (P < 0.05). A preliminary gene expression study showed the positive influence of lactic acid bacteria on the expression of important defense-related marker genes and transcription factors upon FHB. These results indicate the potential of lactic acid bacteria to be included as part of an integrated pest management strategy for the management of FHB disease. This strategy will reduce FHB severity and deoxynivalenol (DON) contamination of spring barley, leading to high acceptance in the grain market.

Antifungal Mechanisms and Application of Lactic Acid Bacteria in Bakery Products: A Review

Bakery products are nutritious, but they are susceptible to fungal contamination, which leads to a decline in quality and safety. Chemical preservatives are often used to extend the shelf-life of bakery products, but long-term consumption of these preservatives may increase the risk of chronic diseases. Consumers increasingly demand food with fewer chemical preservatives. The application of lactic acid bacteria (LAB) as a novel biological preservative not only prolongs the shelf-life of bakery products but also improves the baking properties of bakery products. This review summarizes different types and action mechanisms of antifungal compounds produced by LAB, factors affecting the production of antifungal compounds, and the effects of antifungal LAB on bakery products, providing a reference for future applications of antifungal LAB in bakery products.

Preliminary sampling of aflatoxin M1 contamination in raw milk from dairy farms using feed ingredients from Rwanda

Milk is susceptible to aflatoxin M1 (AFM₁) contamination when dairy cattle consume feed contaminated with aflatoxins and is considered as a public health concern. This pilot study assessed the prevalence and amount of total aflatoxin contamination in commercially available dairy feed and the corresponding AFM₁ contamination in raw milk from samples collected at farms using local, commercially available dairy feed across Rwanda's five provinces. The inclusion criteria to select dairy farm participants were (1) to have at least two cows and (2) use of commercially prepared dairy feeds. Importantly, the majority of cattle rearing households in Rwanda rely principally on grazing or other freely available feedstock, rather than on commercially prepared feeds. In total, 170 raw milk samples were collected during one sampling period from dairy farms using commercially prepared dairy feeds. In addition, 154 dairy feed samples were collected simultaneously with the milk samples. These farms were previously targeted in a larger study measuring aflatoxin contamination of Rwandan feeds and feed ingredients. The mean AFM₁ concentration in these samples was 0.89 ± 1.64 µg/l (median: 0.33 µg/l) with a maximum of 14.5 µg/l. Maize bran was the principal dairy feed ingredient used by farmers in the sampling, representing more than 65% of the total feed samples collected, with mean aflatoxin concentration of 90.5 µg/kg (median 32.3 µg/kg). The authors note that this preliminary sampling is not generalizable across Rwandan milk production and consumption; the limited pilot study presented here was not designed with the robustness necessary for broad-scale generalization. Thus, the data presented should not be broadly applied outside of the context of the study.

[In vivo and In vitro Mitigation Effects of Lactic Acid Bacteria Derived from Fresh Vegetables on Aflatoxins]

Aflatoxins (AFs) are known to be oncogenic mycotoxins. This study investigated the mitigation effects of lactic acid bacteria (LAB) isolated from four types of vegetable, cucumber, Chinese cabbage, Japanese radish and eggplant, which are used to make Japanese traditional fermented pickles, on AFs. Using aflatoxin M₁ (AFM₁) binding assay for screening, four representative strains were selected (one from each vegetable) from total 94 LAB strains, based on the highest binding ratio. The ranges of the binding ratio of these representative strains to aflatoxin B₁ (AFB₁), aflatoxin B₂, aflatoxin G₁, aflatoxin G₂ and AFM₁ were 57.5%-87.9% for the LAB strain derived from cucumber, 18.9%-43.9% for the LAB strain derived from Chinese cabbage, 26.4%-41.7% for the LAB strain derived from Japanese radish, and 15.0%-42.6% for the LAB strain derived from eggplant. The strains isolated from cucumber, Chinese cabbage, Japanese radish and eggplant were identified as Lactococcus lactis subsp. lactis, Weissella cibaria, Leuconostoc mesenteroides and Leu. mesenteroides, respectively. An in vitro binding assay of the four strains under acidic conditions showed that the number of living bacteria decreased, while the binding ratio increased in some strains, suggesting that the LAB maintained their capacity to bind aflatoxins even in an environment that imitated the stomach. An in vivo experiment using L. lactis subsp. lactis derived from cucumber revealed that the bacteria significantly inhibited the absorption of AFB₁ into blood. These results showed that the LAB used for Japanese vegetable pickles was an effective binding agent of AFs and suggested that they might play a role in mitigating AF absorption.

Effect of Lactic Acid Bacteria on the Fermentation Quality and Mycotoxins Concentrations of Corn Silage Infested with Mycotoxigenic Fungi

This study was conducted to evaluate the effect of lactic acid bacteria (LAB) on fermentation quality, mycotoxin concentrations, and microbial communities of whole-crop corn silages infested with mycotoxigenic fungi. Cultured spores (10⁶ cfu/mL) of mycotoxigenic Aspergillus flavus and Fusarium graminearum were sprayed (5 mL) on corn forage on 27 July and 10 August 2018. On 21 August 2018, sprayed (FI; 3 plots) and unsprayed (NFI; 3 plots) corn forage were harvested at the 1/2 kernel milk line stage, followed by chopping and ensiling without inoculants (CON), or with Lactobacillus buchneri (LB, 1 × 10⁶ cfu/g FW), Lactobacillus plantarum (LT, 1 × 10⁶ cfu/g FW), or L. buchneri + L. plantarum (BT: both L. buchneri and L. plantarum applied at 0.5 × 10⁶ cfu/g FW). After 90 d of ensiling, FI silages had a higher (p < 0.05) pH value and higher acetic acid (ACA), ethanol, and ammonia nitrogen (ammonia N) concentrations, but lower (p < 0.05) lactic acid (LA) concentrations than NFI silage. The inoculants decreased pH and increased LA concentration and LA/ACA compared with CON. The aflatoxin B₁ (AFB₁) was only detected in FI fresh corn and silages; ensiling decreased (p < 0.05) AFB₁ concentration compared with fresh corn, and LB and BT decreased AFB₁ concentration compared with CON. The zearalenone (ZEN), deoxynivalenol (DON), and fumonisin B₁ (FB₁) concentrations were similar (p < 0.05) for NFI silages, while ZEN concentration in BT was the lowest (p < 0.05) among all FI silages; DON and FB₁ concentrations in LB, LT, and BT silages were significantly lower (p < 0.05) than those of CON in FI silages. The fungal infestation increased the bacterial and fungal diversity of silages compared with NFI silages. The FI silages had a higher relative abundance (RA) of Lactobacillus, Weissella, Wickerhamomyces, Pichia, and Epicoccum than the corresponding NFI silages. The RA of Aspergillus and Fusarium markedly decreased after 90 d of ensiling, and the inoculation expanded this trend irrespective of fungal infestation. The Penicillium in FI silages survived after 90 d of ensiling, while the inoculants decreased the RA of Penicillium. Inoculants mitigate the adverse effects of fungal infestation on corn silage quality by changing the bacterial and fungal communities.

Integrated Mycotoxin Management System in the Feed Supply Chain: Innovative Approaches

Exposure to mycotoxins is a worldwide concern as their occurrence is unavoidable and varies among geographical regions. Mycotoxins can affect the performance and quality of livestock production and act as carriers putting human health at risk. Feed can be contaminated by various fungal species, and mycotoxins co-occurrence, and modified and emerging mycotoxins are at the centre of modern mycotoxin research. Preventing mould and mycotoxin contamination is almost impossible; it is necessary for producers to implement a comprehensive mycotoxin management program to moderate these risks along the animal feed supply chain in an HACCP perspective. The objective of this paper is to suggest an innovative integrated system for handling mycotoxins in the feed chain, with an emphasis on novel strategies for mycotoxin control. Specific and selected technologies, such as nanotechnologies, and management protocols are reported as promising and sustainable options for implementing mycotoxins control, prevention, and management. Further research should be concentrated on methods to determine multi-contaminated samples, and emerging and modified mycotoxins.

Antifungal properties and AFB1 detoxification activity of a new strain of Lactobacillus plantarum

Aflatoxin B₁ is the most toxic mycotoxin and has strong carcinogenicity. In this study, coumarin was employed as the sole carbon source to isolate the microorganisms that had AFB₁ detoxification activity. Among106 strains isolated from fermented foods, one potential strain was identified as Lactobacillus plantarum based on 16S rDNA sequence. Removal ratio of AFB₁ was 89.5%, inhibitory ratio to A. flavus growth was 42.8% and inhibitory ratio to A. flavus spores growth was as high as 100%. Coumarin utilization indicated that the AFB₁ could be decomposed by the strain. The strong antifungal ability against A. flavus growth and spores growth revealed that AFB₁ secretion could be highly inhibited by the strain. In addition, High Performance Liquid Chromatography analysis indicated that fermentation supernatant of the strain could degrade AFB₁. Scanning Electron Microscopy and Transmission Electron Microscopy indicated that the strain had a strong resistance to AFB₁ and had ability to bind AFB₁ on the strain surface. Possible detoxification pathway to AFB₁ was proposed. Therefore, the strain with high antifungal, antimycotoxigenic abilities might have great potential and immense value in detoxifying AFB₁. The use of the strain might be a promising biocontrol strategy to detoxify AFB₁.

Biocontrol of Aflatoxins Using Non-Aflatoxigenic Aspergillus flavus: A Literature Review

Aflatoxins (AFs) are mycotoxins, predominantly produced by Aspergillus flavus, A. parasiticus, A. nomius, and A. pseudotamarii. AFs are carcinogenic compounds causing liver cancer in humans and animals. Physical and biological factors significantly affect AF production during the pre-and post-harvest time. Several methodologies have been developed to control AF contamination, yet; they are usually expensive and unfriendly to the environment. Consequently, interest in using biocontrol agents has increased, as they are convenient, advanced, and friendly to the environment. Using non-aflatoxigenic strains of A. flavus (AF⁻) as biocontrol agents is the most promising method to control AFs’ contamination in cereal crops. AF⁻ strains cannot produce AFs due to the absence of polyketide synthase genes or genetic mutation. AF⁻ strains competitively exclude the AF⁺ strains in the field, giving an extra advantage to the stored grains. Several microbiological, molecular, and field-based approaches have been used to select a suitable biocontrol agent. The effectiveness of biocontrol agents in controlling AF contamination could reach up to 99.3%. Optimal inoculum rate and a perfect time of application are critical factors influencing the efficacy of biocontrol agents.

Management strategies for aflatoxin risk mitigation in maize, dairy feeds and milk value chains—case study Kenya

Widespread aflatoxin contamination of a great number of food and feed crops has important implications on global trade and health. Frequent occurrence of aflatoxin in maize and milk poses serious health risks to consumers because these commodities are staple foods in many African countries. This situation calls for development and implementation of rigorous aflatoxin control measures that encompass all value chains, focusing on farms where food and feed-based commodities prone to aflatoxin contamination are cultivated. Good agricultural practices (GAP) have proven to be an effective technology in mitigation and management of the aflatoxin risk under farm conditions. The prevailing global climate change is shown to increase aflatoxin risk in tropical and subtropical regions. Thus, there is an urgent need to devise and apply novel methods to complement GAP and mitigate aflatoxin contamination in the feed, maize and milk value chains. Also, creation of awareness on aflatoxin management through training of farmers and other stakeholders and enforcement of regular surveillance of aflatoxin in food and feed chains are recommended strategies. This literature review addresses the current situation of aflatoxin occurrence in maize, dairy feeds and milk produced and traded in Kenya and current technologies applied to aflatoxin management at the farm level. Finally, a case study in Kenya on successful application of GAP for mitigation of aflatoxin risk at small-scale farms will be reviewed.

Mycotoxin Removal by Lactobacillus spp. and Their Application in Animal Liquid Feed

The removal of mycotoxins from contaminated feed using lactic acid bacteria (LAB) has been proposed as an inexpensive, safe, and promising mycotoxin decontamination strategy. In this study, viable and heat-inactivated L. acidophilus CIP 76.13T and L. delbrueckii subsp. bulgaricus CIP 101027T cells were investigated for their ability to remove aflatoxin B₁ (AFB₁), ochratoxin A (OTA), zearalenone (ZEA), and deoxynivalenol (DON) from MRS medium and PBS buffer over a 24 h period at 37 °C. LAB decontamination activity was also assessed in a ZEA-contaminated liquid feed (LF). Residual mycotoxin concentrations were determined by UHPLC-FLD/DAD analysis. In PBS, viable L. acidophilus CIP 76.13T and L. delbrueckii subsp. bulgaricus CIP 101027T cells removed up to 57% and 30% of ZEA and DON, respectively, while AFB₁ and OTA reductions were lower than 15%. In MRS, 28% and 33% of ZEA and AFB₁ were removed, respectively; OTA and DON reductions were small (≤15%). Regardless of the medium, heat-inactivated cells produced significantly lower mycotoxin reductions than those obtained with viable cells. An adsorption mechanism was suggested to explain the reductions in AFB₁ and OTA, while biodegradation could be responsible for the removal of ZEA and DON. Both viable LAB strains reduced ZEA by 23% in contaminated LF after 48 h of incubation. These findings suggest that LAB strains of L. acidophilus CIP 76.13T and L. delbrueckii subsp. bulgaricus CIP 101027T may be applied in the feed industry to reduce mycotoxin contamination.

In vitro activity of encapsulated lactic acid bacteria on aflatoxin production and growth of Aspergillus Spp

This study aimed to investigate the potential ability of simultaneously used L. acidophilus(LA-5), L.rhamnosus(LGG), and L.casei(LC-01) in encapsulated (E) and nonencapsulated (NE) forms in mycelial growth of Aspergillus spp and aflatoxin production by A. flavus. In order to assess the zone of fungal growth inhibition by E and NE lactic acid bacteria, the agar well diffusion method was applied. Quantification of aflatoxin was performed using a high-performance liquid chromatography technique. Lactic acid bacteria exhibited high antifungal activity and significantly reduced AFB1, AFB2, AFG1, and AFG2 production in both E and NE forms compared to the control group. The percentage of reduction in total AFs production in treated samples with E and NE lactic acid bacteria was 94.1% and 95.5%, respectively. These results suggested that simultaneously used lactic acid bacteria in E and NE forms can prevent growth and decrease aflatoxin production of toxigenic aspergilla.

Biodegradation of aflatoxin by bacterial species isolated from poultry farms

Aflatoxins are carcinogenic compounds produced by certain Aspergillus spp and naturally contaminate poultry rations. Exposure to low levels of Aflatoxin B1 (AFB1) in poultry feeds is the second most threatening issue facing the poultry industry in Egypt; it can cause a reduction in growth, egg production, and compromised immune functions, resulting in significant economic loss. Hence, a safe, effective and eco-friendly detoxification method is strongly required. Biological decontamination is a promising approach to reduce aflatoxin levels within threshold limits. This study explores the biodegradation capacity of bacteria isolated from the moldy feed, soil and poultry feces in various poultry farms against AFB1 (100 ppb), G1 (100 ppb), B2 (30 ppb), G2 (30 ppb). Sixty-five bacterial isolates were initially screened using coumarin media with a concentration of (0.01%-0.5%) coumarin. Only one soil isolate (SZ1) grew at the highest concentration (0.5%). Coumarin and Aflatoxin degradation rates of ten promising isolates were measured using spectrophotometry and HPLC. Six isolates reduced AFG1 by more than 90% in the liquid medium, five reduced AFB2 while only four did the same with AFB1& AFG2. Impressively, isolate SZ1 (identified as Pseudomonas fluorescens) exhibited the best degradation capacity to both coumarin and aflatoxin with 100% degradation of AFG1 and 99% degradation of AFB1, AFB2 and AFG2. Biochemical and molecular identification of the ten isolates revealed that they belong to four genera; Bacillus (6), Pseudomonas (2), Enterococcus (1) and Stenotrophomonas (1). Factors affecting Pseudomonas fluorescens SZ1 degradation activity was further investigated. Optimum temperature, time and pH for maximum aflatoxin degradation were at 37 °C, 72 h and 7, respectively. Treatment with proteinase K reduced the degradation activity of G1 (31% ± 1.438), B1 (42% ± 1.438), G2 (19% ± 1.097), and B2 (25% ± 1.732), suggesting that the effective component in aflatoxin degradation may be protein in nature. Our study suggests the biocontrol potential of several different species isolated from poultry farms; B. haynesii, B. licheniformis, B. tequilensis, B. subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, Enterococcus casseliflavus, and Stenotrophomonas maltophilia. The results proposed Pseudomonas fluorescens SZ1 as an excellent candidate for bioremediation and decontamination of aflatoxin in feed matrices. To the best of our knowledge, this is the first report identifying B. haynesii, Enterococcus casseliflavus, B. tequilensis and B. amyloliquefaciens with aflatoxin degradation activity.

Biological Control and Mitigation of Aflatoxin Contamination in Commodities

Aflatoxins (AFs) are toxic secondary metabolites produced mostly by Aspergillus species. AF contamination entering the feed and food chain has been a crucial long-term issue for veterinarians, medicals, agroindustry experts, and researchers working in this field. Although different (physical, chemical, and biological) technologies have been developed, tested, and employed to mitigate the detrimental effects of mycotoxins, including AFs, universal methods are still not available to reduce AF levels in feed and food in the last decades. Possible biological control by bacteria, yeasts, and fungi, their excretes, the role of the ruminal degradation, pre-harvest biocontrol by competitive exclusion or biofungicides, and post-harvest technologies and practices based on biological agents currently used to alleviate the toxic effects of AFs are collected in this review. Pre-harvest biocontrol technologies can give us the greatest opportunity to reduce AF production on the spot. Together with post-harvest applications of bacteria or fungal cultures, these technologies can help us strictly reduce AF contamination without synthetic chemicals.

Efficacy of Potentially Probiotic Fruit-Derived Lactobacillus fermentum, L. paracasei and L. plantarum to Remove Aflatoxin M1 In Vitro

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.

Aflatoxin B1 and Sterigmatocystin Binding Potential of Non-Lactobacillus LAB Strains

Research on the ability of lactic acid bacteria (LAB) to bind aflatoxin B1 (AFB1) has mostly been focusing on lactobacilli and bifidobacteria. In this study, the AFB1 binding capacities of 20 Enterococcus strains belonging to E. casseliflavus, E. faecalis, E. faecium, E. hirae, E. lactis, and E. mundtii, 24 Pediococcus strains belonging to species P. acidilactici, P. lolii, P. pentosaceus, and P. stilesii, one strain of Lactococcus formosensis and L.garviae, and 3 strains of Weissella soli were investigated in MRS broth at 37 °C at 0.2 µg/mL mycotoxin concentration. According to our results, among non-lactobacilli LAB, the genera with the best AFB1 binding abilities were genus Pediococcus, with a maximum binding percentage of 7.6% by P. acidilactici OR83, followed by genus Lactococcus. For AFB1 bio-detoxification purposes, beside lactobacilli, pediococci can also be chosen, but it is important to select a strain with better binding properties than the average value of its genus. Five Pediococcus strains have been selected to compare their sterigmatocystin (ST) binding abilities to AFB1 binding, and a 2-3-fold difference was obtained similar to previous findings for lactobacilli. The best strain was P. acidilactici OR83 with 18% ST binding capacity. This is the first report on ST binding capabilities of non-Lactobacillus LAB strains.

A Comparative Interrupted Times Series on the Health Impact of Probiotic Yogurt Consumption Among School Children From Three to Six Years Old in Southwest Uganda

Introduction: Following a school milk feeding program in Southwest Uganda, we initiated a probiotic yogurt school feeding program in the same region in 2018. In order to investigate the potential health benefits from probiotic yogurt we conducted an observational study, where we compared the effect of the consumption of locally produced probiotic yogurt containing Lactobacillus rhamnosus yoba 2012 to milk in pre-primary schoolchildren from different schools on the occurrence of respiratory tract infections (common cold) and skin infections (e.g., tinea capitis). Method: A comparative interrupted time series over a period of 3 weeks of baseline followed by 9 weeks of 100 ml of probiotic yogurt or milk consumption for 5 days per week. In total 584 children attending five different schools were followed during consumption of probiotic yogurt and 532 children attending five other schools during consumption of milk. Incidences of respiratory tract infection symptoms and skin infection symptoms, changes in anthropometric indicators and absenteeism were recorded. Results: Over the course of the study period the incidence rate for common cold symptoms decreased faster in the yogurt group than in the milk group (p = 0.09) resulting in a final RR of 0.85 (95% CI: 0.5-1.4) at the end of the observational period. The incidence rate of skin infection related symptoms also reduced faster in the yogurt group compared to the milk group (p < 0.0001) resulting in a relative risk factor (RR) of 0.6 (CI: 0.4-0.9) at the end of the observational period. Anthropometric indicators and level of absenteeism did not show significant differences between yogurt and milk. Conclusion: Notwithstanding the observed positive trend and effect of probiotic yogurt on the incidences of common cold and skin infections, respectively, we consider the results of this comparative interrupted time series inconclusive due to differences in the recorded health parameters between the probiotic yogurt and milk control groups at base line, and fluctuations over the course of the intervention period. An improved study design, with more uniform study groups, a longer intervention period and a third control group without yogurt or milk is required to draw definitive conclusions.

Fungi and Aflatoxin Levels in Traditionally Processed Cassava (Manihot esculenta Crantz) Products in Homa Bay County, Kenya

Cassava (Manihot esculenta Crantz) is a major source of carbohydrates, calcium, vitamins (B and C), and essential minerals and is the third most important source of calories in the tropics. However, it is not clear if the traditional processing methods expose the products to microbial contamination. This study assessed the levels of fungi and aflatoxin contamination in traditionally processed cassava products (Akuoga and Abeta). A total of 38 samples were collected from the local markets in 7 subcounties in Homa Bay County, Kenya. The levels of aflatoxin were determined using an indirect competitive ELISA protocol. Yeast and mould contamination was determined using ISO 21527-2 method. Mean aflatoxin levels in chopped, fermented, and sun-dried cassava (Akuoga) were 0.36 μg/kg compared to 0.25 μg/kg in chopped and sun-dried (Abeta) products. Aflatoxin contamination was detected in 55% of the samples and ranged from 0–5.33 μg/kg. These levels are within 10 μg/kg recommended by the CODEX STAN 193-1995. Yeast and mould counts in fermented and chopped sun-dried products were 3.16 log Cfu/g and 2.92 log Cfu/g, respectively. The yeast and mould counts were above standards set by East African Standard 739:2010 in 62% (Akuoga) and 58% (Abeta). The most prevalent fungal species were Saccharomyces cerevisiae (68.4%) and Candida rugosa (68%) followed by Candida parapsilosis (18.4%), Candida tropicalis (15.8%), Candida humilis (15.8%), and Aspergillus spp. (5.3%). Aspergillus spp. was the only mycotoxigenic mould isolated from the samples. The study shows that cassava consumers are exposed to the risk of aflatoxin poisoning. The study, therefore, recommends appropriate surveillance to ensure safety standards.

Effect of thermal processing and traditional flavouring mixture on mycotoxin reduction in pistachio

The effect of heating (roasting and microwave radiation heating) along with a traditional pistachio flavouring mixture (containing verjuice, thyme extract, and sodium chloride) was investigated on reducing aflatoxins (AFs) and ochratoxin A (OTA) in pistachios. The naturally and artificially contaminated samples were soaked in the flavouring mixture (for 5, 10 and 24 h) and then subjected to roasting (at 120 and 150 °C for 50 min) and heating by microwave radiation (6 and 10 min). The residual mycotoxins were determined by high-performance liquid chromatography. The results showed that all treatments were able to reduce mycotoxin content (aflatoxin B1, B2, G1, G2 and OTA) significantly (P<0.05), up to 85.7±2.5% (during roasting) and up to 72.5±2.6% (during heating by microwave radiation). The highest reduction of AFs and OTA (ranging from 51.7±2.3 to 85.7±2.5%) was found when the contaminated (naturally and artificially) samples were soaked in the traditional mixture for 24 h and roasted at 150 °C. It could be concluded that the traditional flavouring method in combination with the roasting process or heating by microwave radiation could be applied as a useful and safe method for mycotoxin degradation in pistachio. Although, complete elimination of mycotoxins was not achieved, the method reduced mycotoxins more than 60% without adverse effect on the taste and appearance of pistachios.

Lactic Acid Bacteria as Antibacterial Agents to Extend the Shelf Life of Fresh and Minimally Processed Fruits and Vegetables: Quality and Safety Aspects

Eating fresh fruits and vegetables is, undoubtedly, a healthy habit that should be adopted by everyone (particularly due to the nutrients and functional properties of fruits and vegetables). However, at the same time, due to their production in the external environment, there is an increased risk of their being infected with various pathogenic microorganisms, some of which cause serious foodborne illnesses. In order to preserve and distribute safe, raw, and minimally processed fruits and vegetables, many strategies have been proposed, including bioprotection. The use of lactic acid bacteria in raw and minimally processed fruits and vegetables helps to better maintain their quality by extending their shelf life, causing a significant reduction and inhibition of the action of important foodborne pathogens. The antibacterial effect of lactic acid bacteria is attributed to its ability to produce antimicrobial compounds, including bacteriocins, with strong competitive action against many microorganisms. The use of bacteriocins, both separately and in combination with edible coatings, is considered a very promising approach for microbiological quality, and safety for postharvest storage of raw and minimally processed fruits and vegetables. Therefore, the purpose of the review is to discuss the biopreservation of fresh fruits and vegetables through the use of lactic acid bacteria as a green and safe technique.

Microbial Safety of Milk Production and Fermented Dairy Products in Africa

In Africa, milk production, processing and consumption are integral part of traditional food supply, with dairy products being a staple component of recommended healthy diets. This review provides an overview of the microbial safety characteristics of milk production and fermented dairy products in Africa. The object is to highlight the main microbial food safety hazards in the dairy chain and to propose appropriate preventive and control measures. Pathogens of public health concern including Mycobacterium bovis, Brucella abortus and Coxiella burnettii, which have largely been eradicated in many developed nations, still persist in the dairy chain in Africa. Factors such as the natural antimicrobial systems in milk and traditional processing technologies, including fermentation, heating and use of antimicrobial additives, that can potentially contribute to microbial safety of milk and dairy products in Africa will be discussed. Practical approaches to controlling safety hazards in the dairy chain in Africa have been proposed. Governmental regulatory bodies need to set the necessary national and regional safety standards, perform inspections and put measures in place to ensure that the standards are met, including strong enforcement programs within smallholder dairy chains. Dairy chain actors would require upgraded knowledge and training in preventive approaches such as good agricultural practices (GAP), hazard analysis and critical control points (HACCP) design and implementation and good hygienic practices (GHPs). Food safety education programs should be incorporated into school curricula, beginning at the basic school levels, to improve food safety cognition among students and promote life-long safe food handling behaviour.

Mycobiota associated with strawberry fruits, their mycotoxin potential and pectinase activity

Forty-three species and variety belonging to 15 genera were collected from 30 strawberry fruit samples on Glucose-Czapek’s agar medium. Among them, Aspergillus flavus, Aspergillus niger and Penicillium citrinum were the most frequent species recovered from 53.3%, 70.0% and 50.0% of the samples, respectively. According to the ITS rDNA sequence, we confirmed the morphological identification result. Moreover, aflatoxin biosynthesis gene omt-A was detected in A. flavus, while Aopks gene was found in A. niger. Interestingly, we could not detect any aflatoxin or ochratoxin biosynthesis genes in the P. citrinum strain. The concentration of detected aflatoxin was 3.5 ppb produced by A. flavus, while A. niger gave 4.1 ppb as ochratoxin. A. flavus was the most pectinase producer among the selected strains, and the highest amount was obtained at 30°C after 6 days of incubation with initial medium pH 8.

Aflatoxins: Occurrence, Exposure, and Binding to Lactobacillus Species from the Gut Microbiota of Rural Ugandan Children

Chronic exposure of children in sub-Saharan Africa to aflatoxins has been associated with low birth weight, stunted growth, immune suppression, and liver function damage. Lactobacillus species have been shown to reduce aflatoxin contamination during the process of food fermentation. Twenty-three Lactobacillus strains were isolated from fecal samples obtained from a cohort of rural Ugandan children at the age of 54 to 60 months, typed by 16S rRNA gene sequencing, and characterized in terms of their ability to bind aflatoxin B1 in vitro. Evidence for chronic exposure of these children to aflatoxin B1 in the study area was obtained by analysis of local foods (maize flour and peanuts), followed by the identification of the breakdown product aflatoxin M1 in their urine samples. Surprisingly, Lactobacillus in the gut microbiota of 140 children from the same cohort at 24 and 36 months showed the highest positive correlation coefficient with stunting among all bacterial genera identified in the stool samples. This correlation was interpreted to be associated with dietary changes from breastfeeding to plant-based solid foods that pose an additional risk for aflatoxin contamination, on one hand, and lead to increased intake of Lactobacillus species on the other.

Mycotoxin contamination and control strategy in human, domestic animal and poultry: A review

Mycotoxins are secondary metabolites produced mainly by fungi belonging to the genera Aspergillus, Fusarium, Penicillium, Claviceps, and Alternaria that contaminate basic food products throughout the world, where developing countries are becoming predominantly affected. Currently, more than 500 mycotoxins are reported in which the most important concern to public health and agriculture include AFB1, OTA, TCTs (especially DON, T-2, HT-2), FB1, ZEN, PAT, CT, and EAs. The presence of mycotoxin in significant quantities poses health risks varying from allergic reactions to death on both humans and animals. This review brings attention to the present status of mycotoxin contamination of food products and recommended control strategies for mycotoxin mitigation. Humans are exposed to mycotoxins directly through the consumption of contaminated foods while, indirectly through carryover of toxins and their metabolites into animal tissues, milk, meat and eggs after ingestion of contaminated feeds. Pre-harvest (field) control of mycotoxin production and post-harvest (storage) mitigation of contamination represent the most effective approach to limit mycotoxins in food and feed. Compared with chemical and physical approaches, biological detoxification methods regarding biotransformation of mycotoxins into less toxic metabolites, are generally more unique, productive and eco-friendly. Along with the biological detoxification method, genetic improvement and application of nanotechnology show tremendous potential in reducing mycotoxin production thereby improving food safety and food quality for extended shelf life. This review will primarily describe the latest developments in the formation and detoxification of the most important mycotoxins by biological degradation and other alternative approaches, thereby reducing the potential adverse effects of mycotoxins.