Influence of carcinogen binding by lactic acid-producing bacteria on tissue distribution and in vivo mutagenicity of dietary carcinogens

Overview of the Mechanistic Potential of Probiotics and Prebiotics in Cancer Chemoprevention

Despite of strides in modern cancer therapeutic strategies, there has not been a successful cure for it until now and prognostic side effects and substantial toxicity to chemotherapy and subsequent homeostatic imbalance remains a major concern for professionals in this field. The significance of the human microbiome in the pathogenesis of cancer is being recognized, documented, and established worldwide. Probiotics and prebiotics are some of the most extensively researched approaches to modulate the microbiota for therapeutic purposes, and research on their potential to prevent and treat cancer has sparked an immense amount of interest. The characteristics of probiotics and prebiotics allow for an array of efficient applications in cancer preventive measures. Probiotics can also be administered coupled with chemotherapy and surgery to alleviate their side effects and help promote the effectiveness of chemotherapeutic drugs. Besides showing promising results they are accompanied by potential risks and controversies that may eventually result in clinical repercussions. This review emphasizes the mechanistic potential and oncosuppressive effects of probiotic and prebiotics through maintenance of intestinal barrier function, modifying innate immune system, immunomodulation, intestinal microbiota metabolism, inhibition of host cell proliferation, preventing pathogen colonization, and exerting selective cytotoxicity against tumor cells.

Probiotic cultures as a potential protective strategy against the toxicity of environmentally relevant chemicals: State-of-the-art knowledge

Environmentally relevant toxic substances may affect human health, provoking numerous harmful effects on central nervous, respiratory, cardiovascular, endocrine and reproductive system, and even cause various types of carcinoma. These substances, to which general population is constantly and simultaneously exposed, enter human body via food and water, but also by inhalation and dermal contact, while accumulating evidence suggests that probiotic cultures are able to efficiently adsorb and/or degrade them. Cell wall of probiotic bacteria/fungi, which contains structures such as exopolysaccharide, teichoic acid, protein and peptidoglycan components, is considered the main place of toxic substances adsorption. Moreover, probiotics are able to induce metabolism and degradation of various toxic substances, making them less toxic and more suitable for elimination. Other probable in vivo protective effects have also been suggested, including decreased intestinal absorption and increased excretion of toxic substances, prevented gut microbial dysbiosis, increase in the intestinal mucus secretion, decreased production of reactive oxygen species, reduction of inflammation, etc. Having all of this in mind, this review aims to summarize the state-of-the-art knowledge regarding the potential protective effects of different probiotic strains against environmentally relevant toxic substances (mycotoxins, polycyclic aromatic hydrocarbons, pesticides, perfluoroalkyl and polyfluoroalkyl substances, phthalates, bisphenol A and toxic metals).

Antimutagenic Activity as a Criterion of Potential Probiotic Properties

The antimutagenic activity of probiotic strains has been reported over several decades of studying the effects of probiotics. However, this activity is rarely considered an important criterion when choosing strains to produce probiotic preparations and functional food. Meanwhile, the association of antimutagenic activity with the prevention of oncological diseases, as well as with a decrease in the spread of resistant forms in the microbiota, indicates its importance for the selection of probiotics. Besides, an antimutagenic activity can be associated with probiotics' broader systemic effects, such as geroprotective activity. The main mechanisms of such effects are considered to be the binding of mutagens, the transformation of mutagens, and inhibition of the transformation of promutagens into antimutagens. Besides, we should consider the possibility of interaction of the microbiota with regulatory processes in eukaryotic cells, in particular, through the effect on mitochondria. This work aims to systematize data on the antimutagenic activity of probiotics and emphasize antimutagenic activity as a significant criterion for the selection of probiotic strains.

The Ability of Probiotic Lactobacillus Strains in Removal of Benzo[a]pyrene: a Response Surface Methodology Study

In this study, the ability of various lactic acid bacteria was assessed in removing benzo[a]pyrene (BaP) from contaminated phosphate buffer saline (PBS). Response surface methodology (RSM) was performed using Box-Behnken design to investigate the effect of four independent variables including pH (5-7), incubation time (1-24 h), cell density (10⁷-10⁹ cfu/mL), and initial BaP concentration (5-15 mg/kg) at three levels to evaluate in vitro removal of BaP as response. The results showed that all the tested strains were able to remove BaP from PBS and this reduction was entirely strain-specific. Bifidobacterium lactis BB-12 followed by Lactobacillus casei TD10 exhibited the lowest binding ability while the highest binding rate was related to Lactobacillus acidophilus LA-5, Lactobacillus delbrueckii subsp. bulgaricus PTCC 1737, Lactobacillus casei TD4, and Lactobacillus brevis TD3, respectively. Cyclohexane washing weakened BaP-bacteria complex, while this complex was not significantly changed by PBS washing. The results showed that BaP binding rate was influenced by pH, cell density, time, and BaP concentration in linear and quadratic manners. Moreover, there were interactions between cell density and time as well as between time and BaP concentration. The highest BaP-binding rate by L. acidophilus LA-5 was 10 ppm of BaP concentration, pH = 5, cell density of 10⁹ cfu/mL, and an incubation period of 24 h. It can be concluded that a range of pH, time, and microbial population is required to obtain maximum binding efficiency for BaP based on the concentration of the toxin and the species of the bacteria.

The Role of Probiotics in Cancer Prevention

Simple Summary

Cancer is considered one of the leading causes of human mortality in the world and is the subject of much research. The risk of developing cancer depends on genetic factors, as well as the body’s immune status. The intestinal microbiome plays very important role in maintaining homeostasis in the human body. Probiotics have gained increasing medical significance due to the beneficial effect on the human body associated with the prevention and support of the treatment of many chronic diseases, including cancer in the absence of side effects. The aim of this review was to summarize the knowledge about the effect of probiotic microorganisms in the prevention of cancer. There is a lot of evidence that the use of probiotics can play an important role in cancer prevention and support anti-cancer therapies.

Abstract

The gut microbiome can play important role in maintaining homeostasis in the human body. An imbalance in the gut microbiome can lead to pro-inflammatory immune responses and the initiation of disease processes, including cancer. The research results prove some strains of probiotics by modulating intestinal microbiota and immune response can be used for cancer prevention or/and as adjuvant treatment during anticancer chemotherapy. This review presents the latest advances in research into the effectiveness of probiotics in the prevention and treatment support of cancer. The described issues concern to the anticancer activity of probiotic microorganisms and their metabolites. In addition, we described the potential mechanisms of probiotic chemoprevention and the advisability of using probiotics.

Protective role of lactic acid bacteria and yeasts as dietary carcinogen-binding agents - a review

The importance of food contaminants in the link between diet and cancer has been widely demonstrated. Therefore, different physical and chemical strategies for the control of human exposure to such dietary carcinogens has been explored; however, most of these strategies are complex, costly, and have low efficiency which limited their applications. Hence, microbiological methods have been receiving more attention. Recent in vitro and in vivo studies have indicated that lactic acid bacteria (LAB) and yeast may act as dietary carcinogen-binding agents. This review describes the promising protective role of strains belonging mainly to the Lactobacillus, Bifidobacterium and Saccharomyces genera by acting as dietary carcinogen-binding agents. This property suggests that these microorganisms may have a protective role by reducing the bioaccessibility of dietary carcinogens, thereby decreasing their toxic effects. The mechanisms by which the binding process takes place have not been completely elucidated; thus, the possible underlying mechanisms and factors influencing carcinogens-binding will be addressed.

Practical analysis of aflatoxin M1 reduction in pasteurized Milk using low dose gamma irradiation

Milk and dairy products can be exposed to potential dangers such as aflatoxin M1 (AFM1). Various factors affect the formation of aflatoxin, which can be due to environmental changes and the lack of suitable substrate for healthy livestock feeding. The goal of this study is to reduce the toxin in pasteurized milk to a level below the European Codex Alimentarius Commission standard. For this purpose, the proper structure of the radioactive granite stone was first designed as a low level gamma irradiation (LLGI) without contact with pasteurized milk, and and the pasteurized milk containing AFM1 that placed in this structure is measured and compared with the control sample values using Association of Official Analytical Chemists (AOAC) method. Then, the reduction of the resulting aflatoxin in the milk and the LLGI dose rate are obtained. The LLGI dose rate is calculated using the Monte Carlo N-Particle Transport Code (MCNP). For simulation, in addition to the spectrum of gamma radiation emitted by radioactive granites, weight percent of each composition of the pasteurized milk and its component elements are also calculated. The results showed a 51.5% reduction of aflatoxin in pasteurized milk after 4 days and 99% reduction after 8 days compared to the control sample. The LLGI dose rate in milk is 0.39 mGy per day. According to the international atomic energy agency (IAEA) report and pervious results, this dose rate level does not significantly affect chemical and sensory quality of milk, but can extend the shelf-life and provide a safer milk. Therefore, the structure constructed using radioactive granite in this study can be considered as one of the suitable methods for reducing aflatoxin.

Detoxification of Heterocyclic Aromatic Amines by Probiotic to Inhibit Medical Hazards

Cancer is the second leading factor of human death in the world. Long-term consumption of cooked red meat brings about various types of cancers like colorectal cancer due to the formation of Heterocyclic Aromatic Amines (HAAs) during the heating process of meat. There are various solutions for the reduction of these toxicants. The aim of this article is to describe probiotic as one of the possible strategies for bioremoval of these carcinogenic and mutagenic substances and change food to functional one as well. The mechanism of biodetoxification is binding by probiotics, which depends on some variables including the probiotic characteristics, kind and content of the mutagens, as well as some properties of media. In this article, after introducing detoxification ability of probiotics and listing of all reported probiotics in this field, the influencing variables are surveyed and finally, opportunities and problems of HAA bioremoval by probiotics are described.

The efficiency of lactic acid bacteria against pathogenic fungi and mycotoxins

Mycotoxins are produced by some fungal species of the genera Aspergillus, Penicillium, and Fusarium and are common contaminants of a wide range of food commodities. Numerous strategies are used to minimise fungal growth and mycotoxin contamination throughout the food chain. This review addresses the use of lactic acid bacteria, which can inhibit fungal growth and participate in mycotoxin degradation and/or removal from contaminated food. Being beneficial for human and animal health, lactic acid bacteria have established themselves as an excellent solution to the problem of mycotoxin contamination, yet in practice their application in removing mycotoxins remains a challenge to be addressed by future research.

Pre-, pro- and synbiotics in cancer prevention and treatment-a review of basic and clinical research

There is a growing appreciation of the role of the human microbiota in the pathophysiology of cancer. Pre-, pro- and synbiotics are some of the best evidenced means of manipulating the microbiota for therapeutic benefit and their potential role in the prevention and treatment of cancer has garnered significant interest. In this review, we discuss how these agents may have oncosuppressive effects by maintaining intestinal barrier function, immunomodulation, metabolism and preventing host cell proliferation. We highlight the epidemiological and trials-based evidence supporting a role for pre-, pro- and synbiotics in the prevention of cancer. Ultimately, there is more evidence in support of these agents as adjuncts in the treatment of cancer. We discuss their roles in optimising the efficacy and/or minimising the adverse effects of chemotherapy and radiotherapy, antibiotics and surgery. Although we see significant promise in the application of pre-, pro- and synbiotics for clinical benefit in oncology patients, the field is very much in its infancy and oncologists face substantial challenges in advising their patients appropriately.

Detoxification of cancerogenic compounds by lactic acid bacteria strains

Carcinogens in food are an important issue that threat people's health right now. Lactic acid bacteria (LAB) strains as well-known probiotics have shown numerous perspectives in being used as a good food additive to confront cancerogenic compounds in recent years. Some LAB strains can remove cancerogenic compounds from medium environment via direct physical binding and avoid re-pollution of poisonous secondary metabolites which are generated from degradation of cancerogenic compounds. This article presents a whole overview of the physical-binding of LAB strains to such common cancerogenic compounds existed in food and feed environments as mycotoxins, polycyclic aromatic hydrocarbons (PAHs), heterocyclic amines (HAs) and pthalic acid esters (PAEs).In most cases, summaries of these published researches show that the binding of LAB strains to cancerogenic compounds is a physical process. Binding sites generally take place in cell wall, and peptidoglycan from LAB cells is the chief binding site. The adsorption of lactic acid bacteria to cancerogenic compounds is strain-specific. Specially, the strains from the two genera Lactobacillus and Bifidobacterium show a better potential in binding cancerogenic compounds. Moreover, we firstly used molecular dynamic computer model as a highly potential tool to simulate the binding behavior of peptidoglycan from Lactobacillus acidophilus to DBP, one of pthalic acid esters with genetic toxicity. It was seen that the theoretical data were quite consistent with the experimental results in terms of the ability of this bacterium to bind DBP. Also, the toxicity reduction of cancerogenic compounds by LAB strains could be achieved either in gastrointestinal model or animal tests and clinical researches as well. In conclusion, carefully selected LAB strains should be a good solution as one of safety strategies to reduce potential risk of cancerogenic compounds from food-based products.

Ability of Soil Isolated Actinobacterial Strains to Prevent, Bind and Biodegrade Ochratoxin A

Ochratoxin A (OTA) is one of the most important mycotoxins, and contaminates several agricultural products, particularly cereals, grapes, maize, barley, spices and coffee. The aim of this project was to reduce the levels of OTA by supplementing the artificially contaminated solutions with seven strains of actinobacteria (AT10, AT8, SN7, MS1, ML5, G10 and PT1) in order to evaluate their capacity for binding and metabolizing the OTA, as well as their ability to reduce the expression of the genes responsible for its production in A. carbonarius. In the first part of this study, we evaluated the capacity of Streptomyces strains for binding OTA on their surfaces after 0, 30 and 60 min of incubation with PBS solution supplemented with OTA. In the second part, we tested the ability of these strains, as well as their supernatants, to detoxify the ISP2 medium. Finally, we studied the effect of the Streptomyces cocultured with Aspergillus carbonarius on the expression of OTA biosynthesis genes. Results showed that, among the strains co-cultured with A. carbonarius, the strain G10 was able to reduce the expression of acpks, acOTApks, acOTAnrps and vea genes, thus reducing OTA from solid PDA medium to 13.50% of reduction. This strain was remarkably able to detoxify and bind OTA up to 47.07%. Strain AT8 was stronger in detoxifying OTA (52.61%), but had no significant effect on the studied gene expression.

Avaliação in vitro da adsorção de aflatoxina B1 por produtos comerciais utilizados na alimentação animal

RESUMO: Objetivou-se avaliar a capacidade de adsorção in vitro de aflatoxina B1 (AFB1) por produtos comerciais utilizados na alimentação animal. Muitas pesquisas estão sendo realizadas para a descontaminação de AFB1 em alimentos. Os produtos comerciais utilizados frequentemente na alimentação de peixes, disponíveis na forma de probióticos, são formados por cepas de bactérias e leveduras utilizadas na maioria dos ensaios de adsorção de micotoxinas. Foram utilizados três produtos comerciais: A, composto por Bacillus subtilis, Bifidobacterium bifidum, Enterococcus faecium e Lactobacillus acidophilus; B, por leveduras secas de Saccharomyces cerevisiae provenientes de cervejaria; e C, por Bacillus subtilis, Bacillus licheniformis e Bacillus pumilus. Cinco suspensões da dose máxima recomendada pelo fabricante de cada produto (0; 25; 50; 75 e 100%) foram testadas contra AFB1 (1000 ng.mL-1) em microtubos para determinação da capacidade de adsorção. Para simular o pH do estômago e do intestino de tilápias do Nilo (Oreochromis niloticus) foram formuladas soluções tampão fosfato salino (PBS), com pH 1,5 e 7,5; respectivamente. Os microtubos foram introduzidos em uma centrífuga com agitação mecânica, a 37ºC por 1 h e depois centrifugados por 10 min a 14.000 rpm; os sobrenadantes foram quantificados por cromatografia líquida de alta eficiência. Os produtos comerciais, nas concentrações máximas, foram capazes de adsorver AFB1 em quantidades de 45,01 a 129,59; 123,90 a 215,59 e 209,98 a 370,73 ng.mL-1, respectivamente. Concluiu-se que todos os produtos comerciais analisados adsorvem AFB1 em condições simuladas de pH gastrointestinal e são candidatos potenciais para adsorção de AFB1 para futuros ensaios in vivo.

Review of the mechanisms of probiotic actions in the prevention of colorectal cancer

The purpose of this review is to discuss the potential mechanisms of probiotics action in colorectal cancer prevention. In this regard, the composition of the intestinal microbiota is considered as an important risk factor in the development of colorectal cancer, and probiotics are able to positively modulate the composition of this microbiota. Studies have shown that the regular consumption of probiotics could prevent the development of colorectal cancer. In this respect, in vitro and experimental studies suggest some potential mechanisms responsible for this anticarcinogenic action. The mechanisms include modification of the intestinal microbiota composition, changes in metabolic activity of the microbiota, binding and degradation of carcinogenic compounds present in the intestinal lumen, production of compounds with anticarcinogenic activity, immunomodulation, improvement of the intestinal barrier, changes in host physiology, inhibition of cell proliferation, and induction of apoptosis in cancer cells. In contrast, very few reports demonstrate adverse effects of probiotic oral supplementation. In light of the present evidence, more specific studies are needed on probiotic bacteria, especially regarding the identification of the bacterial strains with greater anticarcinogenic potential; the verification of the viability of these strains after passing through the gastrointestinal tract; the investigation of potential adverse effects in immunocompromised individuals; and finally establishing the dosage and frequency of use.

Protective activity of probiotic bacteria against 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ) and 2-amino-1-methyl-6-phenyl-1H-imidazo[4,5-b]pyridine (PhIP) - an in vitro study

Heterocyclic aromatic amines (HAAs) are carcinogenic compounds present in a typical Western diet rich in thermally processed meat. These nutritional factors can modulate the cytotoxicity of faecal water (FW) and induce tumours in the human gastrointestinal tract. Supplementation with probiotics is promising in terms of reducing the harmful effects of HAAs in the human body. The aim of the study was in vitro assessment of the protective activity of the probiotic strains Lb. rhamnosus 0900, Lb. rhamnosus 0908, Lb. casei 0919 and Lb. casei DN 114001 against IQ (2-amino-3-methyl-3H-imidazo[4,5-f]quinoline) and PhIP (2-amino-1-methyl-6-phenyl-1H-imidazo[4,5-b]pyridine) after incubation with faeces from 15 persons aged 4 months to 82 years (children, adults and the elderly). The highest mean cytotoxicity of FW was observed for the elderly (63.2% ± 3.7%) and the lowest for children (28.0% ± 9.5%), as estimated by a neutral red uptake assay. The probiotics lowered the average cytotoxicity of FW exposed to IQ or PhIP. The concentration of IQ and PhIP in FW was most effectively reduced by Lb. rhamnosus 0900 (47.5%) and Lb. casei 0919 (45.8%), respectively, as determined by high -performance liquid chromatography. All the tested strains bound PhIP to a higher extent than IQ. In an alkaline comet assay, Lb. casei 0919 and Lb. rhamnosus 0908 displayed the strongest protective effect against IQ and PhIP (up to 80% reduction of DNA damage). Also in a comet assay, Lb. rhamnosus 0908 exhibited antioxidative activity toward H2O2 and PhIP (up to 63% and 69.5% reduction of oxidative DNA damage, respectively). The protective activity of the probiotic strains was specific to a given person's FW, which implies the involvement of intestinal microbiota in the process.

Metabolomics of the bio-degradation process of aflatoxin B1 by actinomycetes at an initial pH of 6.0

Contamination of food and feed by Aflatoxin B1 (AFB1) is a cause of serious economic and health problems. Different processes have been used to degrade AFB1. In this study, biological degradation of AFB1 was carried out using three Actinomycete species, Rhodococcus erythropolis ATCC 4277, Streptomyces lividans TK 24, and S. aureofaciens ATCC 10762, in liquid cultures. Biodegradation of AFB1 was optimised under a range of temperatures from 25 to 40 °C and pH values of 4.0 to 8.0. An initial concentration of 20 µg/mL of AFB1 was used in this study. The amount of AFB1 remaining was measured against time by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC), coupled with UV and mass spectrometry (LC-MS). All species were able to degrade the AFB1, and no significant difference was found between them. AFB1 remained in the liquid culture for R. erythropolis, S. lividans and S. aureofaciens were 0.81 µg/mL, 2.41 µg/mL and 2.78 µg/mL respectively, at the end of the first 24 h. Degradation occurred at all incubation temperatures and the pH with the optimal conditions for R. erythropolis was achieved at 30 °C and pH 6, whereas for S. lividans and S. aureofaciens the optimum conditions for degradation were 30 °C and pH 5. Analysis of the degradative route indicated that each microorganism has a different way of degrading AFB1. The metabolites produced by R. erythropolis were significantly different from the other two microorganisms. Products of degradation were identified through metabolomic studies by utilizing high-resolution mass spectral data. Mass spectrometric analysis indicated that the degradation of AFB1 was associated with the appearance of a range of lower molecular weight compounds. The pathway of degradation or chemical alteration of AFB1 was followed by means of high resolution Fourier transform mass spectrometry (HR-FTMS) analysis as well as through the MS² fragmentation to unravel the degradative pathway for AFB1. AFB1 bio-degradation was coupled with the accumulation of intermediates of fatty acid metabolism and glycolysis. A plausible mechanism of degradation of AFB1 by Rhodococcus was hypothesized.

In vitro aflatoxin B1 binding capacity by two Enterococcus faecium strains isolated from healthy dog faeces

AIM

This study evaluated the binding capacity of aflatoxin B1 (AFB1 ) by two Enterococcus faecium strains (MF4 and GJ40) isolated from faeces from healthy dogs.

MATERIALS AND METHODS

The binding assay was performed using 50 and 100 ppb of AFB1 analysing the effects of the viability, incubation time and pH on AFB1 binding. Binding stability was determined by washing three times the bacteria-AFB1 complexes with phosphate buffer saline.

RESULTS

Both GJ40 and MF4 strains have the ability to remove AFB1 from aqueous solution. Viable cells were slightly more effective in AFB1 binding than nonviable ones for both strains. Enterococcus faeciumGJ40 removes 24-27% and 17-24%, and Ent. faeciumMF4 removes 36-42% and 27-32% of AFB1 (50 and 100 ppb, respectively) throughout a 48 h incubation period. In general, the removal of AFB1 was highest at pH 7.00 for both strains. The stability of the bacteria-AFB1 complex formed was found to be high (up to 50% of AFB1 remained bounded in bacterial cell after three washes with phosphate buffered saline).

CONCLUSION

The Ent. faecium strains assayed are capable of removing AFB1 under different conditions in vitro.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first AFB1 binding assay performed with Ent. faecium strains isolated from dog faeces, being an interesting strategy for AFB1 decontamination of pet food.

Effect of the bread-making process on zearalenone levels

The effects of the bread-making process including fermentation with Saccharomyces cerevisiae and lactic acid bacteria (Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus acidophilus and Lactobacillus fermentum) and baking at 200°C on zearalenone (ZEA) levels were investigated. Standard solutions of ZEA were added to flour and then loaves of bread were prepared. Sourdough and three types of yeast including active dry yeast, instant dry yeast and compressed yeast were used for the fermentation of dough. ZEA levels in flour, dough and bread were determined by HPLC with fluorescence detection after extraction and clean-up on an immunoaffinity column. The highest reduction in levels of ZEA was found in the first fermentation (first proof), while the lowest reduction was observed in the baking stage. In addition, the results showed that compressed yeast had the maximum reduction potential on ZEA levels even at the baking stage.

Probiotic lactic acid bacteria detoxify N-nitrosodimethylamine

Humans can be exposed to N-nitroso compounds (NOCs) due to many environmental sources, as well as endogenous formation. The main nitrosamine found in food products and also synthesised in vivo by intestinal microbiota is N-nitrosodimethylamine (NDMA). It can cause cancer of the stomach, kidney and colon. The effect of four probiotic Lactobacillus strains on NDMA was studied under different culture conditions (24 h in MRS, 168 h in modified MRS N, and 168 h in phosphate buffer). HPLC and GC-TEA methods were used for NDMA determination in supernatants. The influence of lactic acid bacteria on NDMA genotoxicity was investigated by means of the comet assay. Additionally, the effect of NDMA (2-100 µg ml⁻¹) on the growth and survival of the probiotic strains was studied. The results indicate that the bacteria decreased NDMA concentration by up to 50%, depending on the culture conditions, time of incubation, NDMA concentration, pH and bacterial strain. Lb. brevis 0945 lowered the concentration and genotoxicity of NDMA most effectively by up to 50%. This could be due to either adsorption or metabolism. The growth and survival of the bacteria was not affected by any of the tested NDMA concentrations.

Harnessing microbiome and probiotic research in sub-Saharan Africa: recommendations from an African workshop

To augment capacity-building for microbiome and probiotic research in Africa, a workshop was held in Nairobi, Kenya, at which researchers discussed human, animal, insect, and agricultural microbiome and probiotics/prebiotics topics. Five recommendations were made to promote future basic and translational research that benefits Africans.

A potential role of probiotics in colorectal cancer prevention: review of possible mechanisms of action

A number of investigations, mainly using in vitro and animal models, have demonstrated a wide range of possible mechanisms, by which probiotics may play a role in colorectal cancer (CRC) prevention. In this context, the most well studied probiotics are certain strains from the genera of lactobacilli and bifidobacteria. The reported anti-CRC mechanisms of probiotics encompass intraluminal, systemic, and direct effects on intestinal mucosa. Intraluminal effects detailed in this review include competitive exclusion of pathogenic intestinal flora, alteration of intestinal microflora enzyme activity, reduction of carcinogenic secondary bile acids, binding of carcinogens and mutagens, and increasing short chain fatty acids production. Reduction of DNA damage and suppression of aberrant crypt foci formation have been well demonstrated as direct anti-CRC effects of probiotics on intestinal mucosa. Existing evidence clearly support a multifaceted immunomodulatory role of probiotics in CRC, particularly its ability to modulate intestinal inflammation, a well known risk factor for CRC. The effectiveness of probiotics in CRC prevention is dependent on the strain of the microorganism, while viability may not be a prerequisite for certain probiotic anticancer mechanisms, as indicated by several studies. Emerging data suggest synbiotic as a more effective approach than either prebiotics or probiotics alone. More in vivo especially human studies are warranted to further elucidate and confirm the potential role of probiotics (viable and non-viable), prebiotics and synbiotics in CRC chemoprevention.

Detoxification of mycotoxins by probiotic preparation for broiler chickens

Biological decontamination of mycotoxins using microorganisms is one of the well known strategies for the management of mycotoxins in foods and feeds. Among the different potential decontaminating microorganisms,Saccharomyces cerevisiae and lactic acid bacteria represent unique groups, which are widely used in food fermentation and preservation. The aim of this study was to determine the influence of spontaneous fermentation with the use of probiotic bacteria and yeast (Lactobacillus paracasei/casei ŁOCK 0920,L. brevis ŁOCK 0944,L. plantarum ŁOCK 0945,Saccharomyces cerevisiae ŁOCK 0142), on reduction of sum of aflatoxines (B1, B2, G1, G2) and ochratoxin A concentration during fermentation and the microflora pattern during fermentaton. The probiotic bacteria and yeast applied creates a starter culture for flour fermentation that has a stable feature of detoxication of aflatoxines and especially ochratoxin A.

Probiotics in colorectal cancer (CRC) with emphasis on mechanisms of action and current perspectives

Colorectal cancer (CRC) is the third most common form of cancer. Diverse therapies such as chemotherapy, immunotherapy and radiation have shown beneficial effects, but are limited because of their safety and toxicity. Probiotic formulations have shown great promise in CRC as preventive and early stage therapeutics. This review highlights the importance of a balanced intestinal microbiota and summarizes the recent developments in probiotics for treating CRC. Specifically, this report describes evidence of the role of probiotics in modulating the microbiota, in improving the physico-chemical conditions of the gut and in reducing oxidative stress. It also discusses the mechanisms of probiotics in inhibiting tumour progression, in producing anticancer compounds and in modulating the host immune response. Even though some of these effects were observed in several clinical trials, when probiotic formulations were used as a supplement to CRC therapies, the application of probiotics as biotherapeutics against CRC still needs further investigation.

Reduction of aflatoxin level in aflatoxin-induced rats by the activity of probiotic Lactobacillus casei strain Shirota

AIMS

Aflatoxin B1 (AFB1 ) is considered as the most toxic food contaminant, and microorganisms, especially bacteria, have been studied for their potential to reduce the bioavailability of mycotoxins including aflatoxins. Therefore, this research investigated the efficacy of oral administration of Lactobacillus casei Shirota (LcS) in aflatoxin-induced rats.

METHODS AND RESULTS

Sprague Dawley rats were divided into three groups of untreated control, the group induced with AFB1 only, and the group given probiotic in addition to AFB1. In the group induced with AFB1 only, food intake and body weight were reduced significantly. The liver and kidney enzymes were significantly enhanced in both groups induced with AFB1 , but they were lower in the group given LcS. AFB1 was detected from all serum samples except for untreated control group's samples. Blood serum level of AFB1 in the group induced with AFB1 only was significantly higher than the group which received probiotic as a treatment (P < 0·05), and there was no significant difference between the control group and the group treated with probiotic.

CONCLUSIONS

LcS supplementation could improve the adverse effect of AFB1 induction on rats' body weight, plasma biochemical parameters and also could reduce the level of AFB1 in blood serum.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study's outcomes contribute to better understanding of the potential of probiotic to reduce the bioavailability ofAFB1 . Moreover, it can open an opportunity for future investigations to study the efficacy of oral supplementation of probiotic LcS in reducing aflatoxin level in human.

Health-Promoting Properties of Lactobacillus helveticus

Lactobacillus helveticus is an important industrial thermophilic starter that is predominantly employed in the fermentation of milk for the manufacture of several cheeses. In addition to its technological importance, a growing body of scientific evidence shows that strains belonging to the L. helveticus species have health-promoting properties. In this review, we synthesize the results of numerous primary literature papers concerning the ability of L. helveticus strains to positively influence human health. Several in vitro studies showed that L. helveticus possesses many common probiotic properties, such as the ability to survive gastrointestinal transit, adhere to epithelial cells, and antagonize pathogens. In vivo studies in murine models showed that L. helveticus could prevent gastrointestinal infections, enhance protection against pathogens, modulate host immune responses, and affect the composition of the intestinal microbiota. Interventional studies and clinical trials have also demonstrated a number of health-promoting properties of L. helveticus. Finally, several studies suggested that specific enzymatic activities of L. helveticus could indirectly benefit the human host by enhancing the bioavailability of nutrients, removing allergens and other undesired molecules from food, and producing bioactive peptides through the digestion of food proteins. In conclusion, this review demonstrates that in light of the scientific literature presented, L. helveticus can be included among the bacterial species that are generally considered to be probiotic.

In vitro binding of mutagenic heterocyclic aromatic amines by Bifidobacterium pseudocatenulatum G4

Consumption of probiotics has been associated with decreased risk of colon cancer and reported to have antimutagenic/ anti-carcinogenic properties. One possible mechanism for this effect involves physical binding of the mutagenic compounds, such as heterocyclic amines (HCAs), to the bacteria. Therefore, the objective of this study was to examine the binding capacity of bifidobacterial strains of human origin on mutagenic heterocyclic amines which are suspected to play a role in human cancers. In vitro binding of the mutagens Trp-p-2, IQ, MeIQx, 7,8DiMeIQx and PhIP by three bacterial strains in two media of different pH was analysed using high performance liquid chromatography. Bifidobacterium pseudocatenulatum G4 showed the highest decrease in the total HCAs content, followed by Bifidobacterium longum, and Escherichia coli. pH affects binding capacity; the highest binding was obtained at pH 6.8. Gram-positive tested strains were found to be consistently more effective than the gram-negative strain. There were significant decreases in the amount of HCAs in the presence of different cell concentrations of B. pseudocatenulatum G4; the highest decrease was detected at the concentration of 10(10) cfu/ml. The results showed that HCAs were able to bind with all bacterial strains tested in vitro, thus it may be possible to decrease their absorption by human intestine and increase their elimination via faeces.

Effect of oral supplementation of Lactobacillus reuteri in reduction of intestinal absorption of aflatoxin B(1) in rats

The goals of this work were to assess the ability of Lactobacillus reuteri to bind aflatoxin B(1) in the intestinal tract and determine its effect on intestinal absorption of the toxin dispensed in either single or multiple doses in a murine model. Male Wistar rats were used, and two experiments were conducted after bacteria were implanted. Experiment one involved a single-oral dose of toxin, and the subsequent flow cytometric analysis of bacteria isolated from the small intestine and treated with specific FITC-labeled AFB(1) antibodies. The second experiment was carried out supplying the toxin in 7 oral sub-doses, and the later quantification of AFB(1)-Lys adducts in blood samples by ELISA assay. The results demonstrated that L. reuteri was able to bind AFB(1) in the intestinal tract, mostly in the duodenum. Furthermore, the AFB(1)-Lys adducts were present at significantly lower levels in those animals receiving AFB(1) plus bacteria than in those receiving only AFB(1). Our findings confirm that probiotic bacteria could act as biological barriers in normal intestinal conditions thereby reducing the bioavailability of AFB(1) ingested orally in a single or multiple doses, thus avoiding its toxic effects.

Saccharomyces cerevisiae strains from animal environment with in vitro aflatoxin B1 binding ability and anti-pathogenic bacterial influence

Mycotoxins are metabolites produced by fungi growing on foods or feeds and represent a serious hazard to humans and animals. Concerns related to the negative health impact of aflatoxins have led to the investigation of strategies to prevent, eliminate or reduce the presence of these toxins in contaminated products. Saccharomyces cerevisiae strains are among promising candidates that can be used in animal feed for improving the robustness of animals in the production environment. The aim of this work was to isolate and select S. cerevisiae strains from pig environment with aflatoxin B1 (AFB1) binding ability, able to tolerate gastrointestinal conditions and with some potential beneficial properties to the host. S. cerevisiae strains were isolated from animal feed, faeces and gut and identified by morphological and molecular techniques. AFB1 binding percentages varied among yeast strains according to the AFB1 concentration used. The RC016 strain showed the highest adsorption percentage at the three AFB1 concentrations tested in this work (50, 100 and 500 ng/ml) followed by RC008 strain. All yeast strains were able to survive under gastrointestinal conditions and to strongly adhere to Vero cells. All S. cerevisiae strains showed co-aggregation with pathogenic bacteria (Escherichia coli, Enterobacter cloacae and Salmonella enterica sub sp. enterica). Only RC016 and RC008 strongly inhibited the three pathogens assayed. S. cerevisiae strains RC016 and RC008 are promising microorganisms for inclusion in animal feed.

Cancer-preventing attributes of probiotics: an update

Cancer is a serious global public health problem. Cancer incidence and mortality have been steadily rising throughout the past century in most places of the world. There are several epidemiological evidences that support a protective role of probiotics against cancer. Lactic acid bacteria and their probioactive cellular substances exert many beneficial effects in the gastrointestinal tract, and also release various enzymes into the intestinal lumen and exert potential synergistic (LAB) effects on digestion and alleviate symptoms of intestinal malabsorption. Consumption of fermented dairy products with LAB may elicit anti-tumor effects. These effects are attributed to the inhibition of mutagenic activity, the decrease in several enzymes implicated in the generation of carcinogens, mutagens, or tumor-promoting agents, suppression of tumors, and epidemiology correlating dietary regimes and cancer. Specific cellular components in lactic acid bacteria seem to induce strong adjuvant effects including modulation of cell-mediated immune responses, activation of the reticulo-endothelial system, augmentation of cytokine pathways, and regulation of interleukins and tumor necrosis factors. Studies on the effect of probiotic consumption on cancer appear promising, since recent in vitro and in vivo studies have indicated that probiotic bacteria might reduce the risk, incidence and number of tumors of the colon, liver and bladder. The protective effect against cancer development may be ascribed to binding of mutagens by intestinal bacteria, may suppress the growth of bacteria that convert procarcinogens into carcinogens, thereby reducing the amount of carcinogens in the intestine, reduction of the enzymes beta-glucuronidase and beta-glucosidase and deconjugation of bile acids, or merely by enhancing the immune system of the host. There are isolated reports citing that administration of LAB results in increased activity of anti-oxidative enzymes or by modulating circulatory oxidative stress that protects cells against carcinogen-induced damage. These include glutathione-S-transferase, glutathione, glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase. However, there is no direct experimental evidence for cancer suppression in human subjects as a result of the consumption of probiotic cultures in fermented or unfermented dairy products, but there is a wealth of indirect evidence based largely on laboratory studies.

Biological strategies to counteract the effects of mycotoxins

Mycotoxins are fungal secondary metabolites that if ingested can cause a variety of adverse effects on both humans and animals, ranging from allergic responses to death. Therefore, exposure to mycotoxins should be minimized. A variety of physical, chemical, and biological methods have been developed for decontamination and/or detoxification of mycotoxins from contaminated foods and feeds. This overview details the latest developments in the biological control of both fungal infection and mycotoxin formation and describes the detoxification of many of the most important mycotoxins by microorganisms. This review also addresses the potential for use of microorganisms as mycotoxin binders in the gastrointestinal tract of both humans and animals, thereby reducing the potential deleterious effects of exposure to these toxins.