Functional characterization of Lactobacillus plantarum ITEM 17215: A potential biocontrol agent of fungi with plant growth promoting traits, able to enhance the nutritional value of cereal products

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.

Contribution to the characterization of the seed endophyte microbiome of Argania spinosa across geographical locations in Central Morocco using metagenomic approaches

Microbial endophytes are microorganisms that live inside plants, and some of them play important yet understudied roles in plant health, growth, and adaptation to environmental conditions. Their diversity within plants has traditionally been underestimated due to the limitations of culture-dependent techniques. Metagenomic profiling provides a culture-independent approach to characterize entire microbial communities. The argan tree (Argania spinosa) is ecologically and economically important in Morocco, yet its seed endophyte microbiome remains unexplored. This study aimed to compare the bacterial and fungal endophyte communities associated with argan seeds collected from six sites across Morocco using Illumina MiSeq sequencing of the 16S rRNA gene and ITS regions, respectively. Bacterial DNA was extracted from surface-sterilized seeds and amplified using universal primers, while fungal DNA was isolated directly from seeds. Bioinformatics analysis of sequencing data identified taxonomic profiles at the phylum to genus levels. The results indicated that bacterial communities were dominated by the genus Rhodoligotrophos, while fungal communities exhibited varying degrees of dominance between Ascomycota and Basidiomycota depending on site, with Penicillium being the most abundant overall. Distinct site-specific profiles were observed, with Pseudomonas, Bacillus, and Aspergillus present across multiple locations. Alpha diversity indices revealed variation in endophyte richness between seed sources. In conclusion, this first exploration of the argan seed endophyte microbiome demonstrated environmental influence on community structure. While facing limitations due to small sample sizes and lack of ecological metadata, it provides a foundation for future mechanistic investigations into how specific endophyte-host interactions shape argan adaptation across Morocco's diverse landscapes.

Effects of the application of microbiologically activated bio-based fertilizers derived from manures on tomato plants and their rhizospheric communities

Bio-based fertilizers (BBFs) recovered from animal manure are promising products to optimise resources recovery and generate high agricultural yields. However, their fertilization value may be limited and it is necessary to enrich BBFs with microbial consortia to enhance their fertilization value. Three specific microbial consortia were developed according to the characteristics of three different BBFs produced from manure (bio-dried solid fraction, solid fraction of digestate and biochar) to enhance plant growth and product quality. A greenhouse pot experiment was carried out with tomato plants grown with microbiologically activated BBFs applied either as N-organic fertilizers or as an organic amendment. A next generation sequencing analysis was used to characterise the development of each rhizospheric community. All the activated BBFs gave enhanced tomato yields (fresh and dry weight) compared with the non-activated treatments and similar to, or higher than, chemical fertilization. Concerning the tomato fruits' organoleptic quality, lycopene and carotenoids concentrations were improved by biological activation. Metagenomic analysis points at Trichoderma as the main driver of the positive effects, with the effects of added bacteria being negligible or limited at the early stages after fertilization. In the context of the circular economy, the activated BBFs could be used to replace synthetic fertilisers, reducing costs and environmental burdens and increasing production.

Global distribution, toxicity to humans and animals, biodegradation, and nutritional mitigation of deoxynivalenol: A review

Deoxynivalenol (DON) is one of the main types of B trichothecenes, and it causes health-related issues in humans and animals and imposes considerable challenges to food and feed safety globally each year. This review investigates the global hazards of DON, describes the occurrence of DON in food and feed in different countries, and systematically uncovers the mechanisms of the various toxic effects of DON. For DON pollution, many treatments have been reported on the degradation of DON, and each of the treatments has different degradation efficacies and degrades DON by a distinct mechanism. These treatments include physical, chemical, and biological methods and mitigation strategies. Biodegradation methods include microorganisms, enzymes, and biological antifungal agents, which are of great research significance in food processing because of their high efficiency, low environmental hazards, and drug resistance. And we also reviewed the mechanisms of biodegradation methods of DON, the adsorption and antagonism effects of microorganisms, and the different chemical transformation mechanisms of enzymes. Moreover, nutritional mitigation including common nutrients (amino acids, fatty acids, vitamins, and microelements) and plant extracts was discussed in this review, and the mitigation mechanism of DON toxicity was elaborated from the biochemical point of view. These findings help explore various approaches to achieve the best efficiency and applicability, overcome DON pollution worldwide, ensure the sustainability and safety of food processing, and explore potential therapeutic options with the ability to reduce the deleterious effects of DON in humans and animals.

Antifungal activity of probiotic strain Lactiplantibacillus plantarum MYSN7 against Trichophyton tonsurans

The primary objective of this study was to assess the probiotic attributes and antifungal activity of lactic acid bacteria (LAB) against the fungus, Trichophyton tonsurans. Among the 20 isolates screened for their antifungal attributes, isolate MYSN7 showed strong antifungal activity and was selected for further analysis. The isolate MYSN7 exhibited potential probiotic characteristics, having 75 and 70% survival percentages in pH3 and pH2, respectively, 68.73% tolerance to bile, a moderate cell surface hydrophobicity of 48.87%, and an auto-aggregation percentage of 80.62%. The cell-free supernatant (CFS) of MYSN7 also showed effective antibacterial activity against common pathogens. Furthermore, the isolate MYSN7 was identified as Lactiplantibacillus plantarum by 16S rRNA sequencing. Both L. plantarum MYSN7 and its CFS exhibited significant anti-Trichophyton activity in which the biomass of the fungal pathogen was negligible after 14 days of incubation with the active cells of probiotic culture (10⁶ CFU/ml) and at 6% concentration of the CFS. In addition, the CFS inhibited the germination of conidia even after 72 h of incubation. The minimum inhibitory concentration of the lyophilized crude extract of the CFS was observed to be 8 mg/ml. Preliminary characterization of the CFS showed that the active component would be organic acids in nature responsible for antifungal activity. Organic acid profiling of the CFS using LC-MS revealed that it was a mixture of 11 different acids, and among these, succinic acid (9,793.60 μg/ml) and lactic acid (2,077.86 μg/ml) were predominant. Additionally, a scanning electron microscopic study revealed that CFS disrupted fungal hyphal structure significantly, which showed scanty branching and bulged terminus. The study indicates the potential of L. plantarum MYSN7 and its CFS to control the growth of T. tonsurans. Furthermore, in vivo studies need to be conducted to explore its possible applications on skin infections.

Exploring the impact of lactic acid bacteria on the biocontrol of toxigenic Fusarium spp. and their main mycotoxins

The occurrence of fungi and mycotoxins in foods is a serious global problem. Most of the regulated mycotoxins in food are produced by Fusarium spp. This work aimed to assess the antifungal activity of selected lactic acid bacteria (LAB) strains against the main toxigenic Fusarium spp. isolated from cereals. Various machine learning (ML) algorithms such as neural networks (NN), random forest (RF), extreme gradient boosted trees (XGBoost), and multiple linear regression (MLR), were applied to develop models able to predict the percentage of fungal growth inhibition caused by the LAB strains tested. In addition, the ability of the assayed LAB strains to reduce/inhibit the production of the main mycotoxins associated with these fungi was studied by UPLC-MS/MS. All assays were performed at 20, 25, and 30 °C in dual culture (LAB plus fungus) on MRS agar-cereal-based media. All factors and their interactions very significantly influenced the percentage of growth inhibition compared to controls. The efficacy of LAB strains was higher at 20 °C followed by 30 °C and 25 °C. Overall, the order of susceptibility of the fungi to LAB was F. oxysporum > F. poae = F. culmorum ≥ F. sporotrichioides > F. langsethiae > F. graminearum > F. subglutinans > F. verticillioides. In general, the most effective LAB was Leuconostoc mesenteroides ssp. mesenteroides (T3Y6b), and the least effective were Latilactobacillus sakei ssp. carnosus (T3MM1 and T3Y2). XGBoost and RF were the algorithms that produced the most accurate predicting models of fungal growth inhibition. Mycotoxin levels were usually lower when fungal growth decreased. In the cultures of F. langsethiae treated with LAB, T-2 and HT-2 toxins were not detected except in the treatments with Pediococcus pentosaceus (M9MM5b, S11sMM1, and S1M4). These three strains of P. pentosaceus, L. mesenteroides ssp. mesenteroides (T3Y6b) and L. mesenteroides ssp. dextranicum (T2MM3) inhibited fumonisin production in cultures of F. proliferatum and F. verticillioides. In F. culmorum cultures, zearalenone production was inhibited by all LAB strains, except L. sakei ssp. carnosus (T3MM1) and Companilactobacillus farciminis (T3Y6c), whereas deoxynivalenol and 3-acetyldeoxynivalenol were only detected in cultures of L. sakei ssp. carnosus (T3MM1). The results show that an appropriate selection and use of LAB strains can be one of the most impacting tools in the control of toxigenic Fusarium spp. and their mycotoxins in food and therefore one of the most promising strategies in terms of efficiency, positive impact on the environment, food safety, food security, and international economy.

Dynamic Alteration of Microbial Communities of Duckweeds from Nature to Nutrient-Deficient Condition

Duckweeds live with complex assemblages of microbes as holobionts that play an important role in duckweed growth and phytoremediation ability. In this study, the structure and diversity of duckweed-associated bacteria (DAB) among four duckweed subtypes under natural and nutrient-deficient conditions were investigated using V3-V4 16S rRNA amplicon sequencing. High throughput sequencing analysis indicated that phylum Proteobacteria was predominant in across duckweed samples. A total of 24 microbial genera were identified as a core microbiome that presented in high abundance with consistent proportions across all duckweed subtypes. The most abundant microbes belonged to the genus Rhodobacter, followed by other common DAB, including Acinetobacter, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, and Pseudomonas. After nutrient-deficient stress, diversity of microbial communities was significantly deceased. However, the relative abundance of Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Pelomonas, Roseateles and Novosphingobium were significantly enhanced in stressed duckweeds. Functional prediction of the metagenome data displayed the relative abundance of essential pathways involved in DAB colonization, such as bacterial motility and biofilm formation, as well as biodegradable ability, such as benzoate degradation and nitrogen metabolism, were significantly enriched under stress condition. The findings improve the understanding of the complexity of duckweed microbiomes and facilitate the establishment of a stable microbiome used for co-cultivation with duckweeds for enhancement of biomass and phytoremediation under environmental stress.

Antifungal activity of lactic acid bacteria and their application in food biopreservation

Lactic acid bacteria (LAB) are ubiquitous bacteria associated with spontaneous lactic fermentation of vegetables, dairy and meat products. They are generally recognized as safe (GRAS), and they are involved in transformation of probiotic lacto-fermented foods, highly desired for their nutraceutical properties. The antifungal activity is one of the exciting properties of LAB, because of its possible application in food bio-preservation, as alternative to chemical preservatives. Many recent research works have been developed on antifungal activity of LAB, and they demonstrate their capacity to produce various antifungal compounds, (i.e. organic acids, PLA, proteinaceous compounds, peptides, cyclic dipeptides, fatty acids, and other compounds), of different properties (hydrophilic, hydrophobic and amphiphilic). The effectiveness of LAB in controlling spoilage and pathogenic fungi, demonstrated in different agricultural and food products, can be due to the synergistic effect between their antifungal compounds of different properties; where the amphiphilic-compounds allow the contact between the target microbial cell (hydrophilic compartment) and antifungal hydrophobic-compounds. Further studies on the interaction between compounds of these three properties are to de be developed, in order to highlight more their mechanism of action, and make LAB more profitable in improving shelf life and nutraceutical properties of foods.

Lactic Acid Bacteria as Biopreservation Against Spoilage Molds in Dairy Products - A Review

Mold spoilage of dairy products such as yogurt is a concern in dairy industry. Not only does it lead to substantial food waste, economic losses, and even brand image damage, but it may also cause public health concern due to the potential production of mycotoxin. Good hygiene practices are necessary to prevent contamination, but contamination may nevertheless occur at the production site and, not least, at the site of the consumer. In recent years, there has been a growing interest from consumers for "clean label" food products, which are natural, less-processed, and free of added, chemical preservatives, and a wish for shelf lives of considerable length in order to minimize food waste. This has sparked an interest in using lactic acid bacteria (LAB) or their metabolites as biopreservatives as a way to limit the growth of spoilage organisms in dairy products. A range of compounds produced by LAB with potential antifungal activity have been described as contributing factors to the inhibitory effect of LAB. More recently, growth inhibition effects caused by specific competitive exclusion have been elucidated. It has also become clear that the sensitivity toward both individual antifungal compounds and competition mechanisms differ among molds. In this review, the main spoilage molds encountered in dairy products are introduced, and an overview of the antifungal activity of LAB against different spoilage molds is presented including the main antifungal compounds derived from LAB cultures and the sensitivity of the spoilage molds observed toward these compounds. The recent findings of the role of competitive exclusion with emphasis on manganese depletion and the possible implications of this for biopreservation are described. Finally, some of the knowledge gaps, future challenges, and trends in the application of LAB biopreservation in dairy products are discussed.

Antifungal Activity of Lactobacillus plantarum ZZUA493 and Its Application to Extend the Shelf Life of Chinese Steamed Buns

Lactic acid bacteria (LAB) can produce many kinds of antifungal substances, which have been widely proven to have antifungal activity. In this study, 359 strains of LAB were screened for antifungal activity against Aspergillus niger (A. niger) using the 96-well microtiter plate method, and three showed strong activity. Of these, ZZUA493 showed a broad-spectrum antifungal ability against A. niger, Aspergillus oryzae, Trichoderma longibrachiatum, Aspergillus flavus and Fusarium graminearum. ZZUA493 was identified as Lactobacillus plantarum. Protease treatment, the removal of hydrogen peroxide with catalase and heat treatment had no effect on the antifungal activity of the cell-free supernatant (CFS) of ZZUA493; organic acids produced by ZZUA493 appeared to have an important role in fungal growth inhibition. The contents of lactic acid, acetic acid and phenyllactic acid in the CFS tended to be stable at 48 h, and amounted to 28.5, 15.5 and 0.075 mg/mL, respectively. In addition, adding ZZUA493, as an ingredient during their preparation, prolonged the shelf life of Chinese steamed buns. Overall, ZZUA493 appears to have good potential as a fungal inhibitor for food preservation.

Bacterial Communities in the Embryo of Maize Landraces: Relation with Susceptibility to Fusarium Ear Rot

Locally adapted maize accessions (landraces) represent an untapped resource of nutritional and resistance traits for breeding, including the shaping of distinct microbiota. Our study focused on five different maize landraces and a reference commercial hybrid, showing different susceptibility to fusarium ear rot, and whether this trait could be related to particular compositions of the bacterial microbiota in the embryo, using different approaches. Our cultivation-independent approach utilized the metabarcoding of a portion of the 16S rRNA gene to study bacterial populations in these samples. Multivariate statistical analyses indicated that the microbiota of the embryos of the accessions grouped in two different clusters: one comprising three landraces and the hybrid, one including the remaining two landraces, which showed a lower susceptibility to fusarium ear rot in field. The main discriminant between these clusters was the frequency of Firmicutes, higher in the second cluster, and this abundance was confirmed by quantification through digital PCR. The cultivation-dependent approach allowed the isolation of 70 bacterial strains, mostly Firmicutes. In vivo assays allowed the identification of five candidate biocontrol strains against fusarium ear rot. Our data revealed novel insights into the role of the maize embryo microbiota and set the stage for further studies aimed at integrating this knowledge into plant breeding programs.

Bioaccessibility and bioavailability of bioactive compounds from yellow mustard flour and milk whey fermented with lactic acid bacteria

Microbial fermentation with lactic acid bacteria (LAB) is a natural food biopreservation method. Yellow mustard and milk whey are optimum substrates for LAB fermentation. The aim of the present study was to evaluate the bioaccessibility and bioavailability of bioactive compounds from yellow mustard flour and milk whey both with and without LAB fermentation. All extracts were subjected to a simulated digestion process. Total polyphenols, DL-3-phenyllactic acid (PLA), lactic acid, and the antioxidant activity were determined in the studied matrices before and after simulated digestion. Yellow mustard flour was significantly richer in total polyphenols, whereas significantly higher concentrations of PLA and lactic acid were observed in milk whey. Similar antioxidant activity was determined in both ingredients being in all cases strongly reduced after in vitro digestion. Higher bioaccessibility was found for polyphenols and PLA in milk whey. Transepithelial transport of total polyphenols was higher in yellow mustard flour compared to milk whey, reaching bioavailability values between 3-7% and 1-2%, respectively. PLA transepithelial transport was only significant in both fermented matrices with bioavailability around 4-6%. Transepithelial transport of lactic acid reached values of 31-34% (bioavailability ∼ 22%) and 15-78% (bioavailability ∼ 3%) in milk whey and yellow mustard flour, respectively. LAB fermentation showed beneficial effects on enriching extracts with PLA, lactic acid, and antioxidant activity, as well as increasing bioaccessibility of these acids in yellow mustard flour and total polyphenol bioavailability in milk whey. Results pointed to yellow mustard flour and milk whey as natural preservative ingredients used in the food industry, especially when fermented with LAB.

Impact of a bacterial consortium on the soil bacterial community structure and maize (Zea mays L.) cultivation

Microorganisms are often applied as biofertilizer to crops to stimulate plant growth, increase yields and reduce inorganic N application. The survival and proliferation of these allochthonous microorganisms in soil is a necessary requisite for them to promote plant growth. We applied a sterilized or unsterilized not commercialized bacterial consortium mixed with cow manure leachate used by a farmer as biofertilizer to maize (Zea mays L.) in a greenhouse experiment, while maize development and the bacterial community structure was determined just before the biofertilizer was applied a first time (day 44), after three applications (day 89) and after six application at the end of the experiment (day 130). Application of sterilized or unsterilized biofertilizer with pH 4.3 and 864 mg NH₄⁺-N kg^-1 had no significant effect on maize growth. The application of the biofertilizer dominated by Lactobacillus (relative abundance 11.90%) or the sterilized biofertilizer changed the relative abundance of a limited number of bacterial groups, i.e. Delftia, Halomonas, Lactobacillus and Stenotrophomonas, without altering significantly the bacterial community structure. Cultivation of maize, however, affected significantly the bacterial community structure, which showed large significant variations over time in the cultivated and uncultivated soil. It was concluded that the bacteria applied as a biofertilizer had only a limited effect on the relative abundance of these groups in uncultivated or soil cultivated with maize.

Sensitivity of Molds From Spoiled Dairy Products Towards Bioprotective Lactic Acid Bacteria Cultures

Fungal spoilage of dairy products is a major concern due to food waste and economical losses, some fungal metabolites may furthermore have adverse effects on human health. The use of lactic acid bacteria (LAB) is emerging as a potential clean label alternative to chemical preservatives. Here, our aim was to characterize the growth potential at three storage temperatures (5, 16, and 25°C) of a panel of molds (four Mucor and nine Penicillium strains) isolated from dairy products, then investigate the susceptibility of the molds toward 12 LAB cultures. Fungal cell growth and morphology in malt extract broth was monitored using oCelloScope at 25°C for 24 h. Mucor plumbeus 01180036 was the fastest growing and Penicillium roqueforti ISI4 (P. roqueforti ISI4) the slowest of the tested molds. On yogurt-agar plates, all molds grew at 5, 16, and 25°C in a temperature-dependent manner with Mucor strains growing faster than Penicillium strains regardless of temperature. The sensitivity toward 12 LAB cultures was tested using high-throughput overlay method and here all the molds except P. roqueforti ISI4 were strongly inhibited. The antifungal action of these LAB was confirmed when spotting mold spores on agar plates containing live cells of the LAB strains. However, if cells were removed from the fermentates, the inhibitory effects decreased markedly. The antifungal effects of volatiles tested in a plate-on-plate system without direct contact between mold and LAB culture media were modest. Some LAB binary combinations improved the antifungal activity against the growth of several molds beyond that of single cultures in yogurt serum. The role of competitive exclusion due to manganese depletion was examined as a possible antifungal mechanism for six Penicillium and two Mucor strains. It was shown that this mechanism was a major inhibition factor for the molds tested apart from the non-inhibited P. roqueforti ISI4 since addition of manganese with increasing concentrations of up to 0.1 mM resulted in partly or fully restored mold growth in yogurt. These findings help to understand the parameters influencing the mold spoilage of dairy products and the interactions between the contaminating strains, substrate, and bioprotective LAB cultures.

Production of glycerol by Lactobacillus plantarum NRRL B-4496 and formation of hexamine during fermentation of pea protein enriched flour

Suspensions of pea protein enriched flour (PP) inoculated with Lactobacillus plantarum NRRL B-4496 and uninoculated PP suspensions were incubated in vials covered with airtight caps. Organic compound compositions of fermented and unfermented PP suspensions (F-PP and U-PP, respectively) were analyzed using solid phase microextraction (SPME) coupled with gas chromatography - mass-spectrometry (GCMS). Acetic acid was detected in all samples; pH dropped from pH 6.5 to pH 4.1 in L. plantarum F-PP and to pH 5.3 in uninoculated F-PP. Abundance of acetic acid and minuscule presence of lactic acid in L. plantarum F-PP suggested that fermentation proceeded preferentially via the pyruvate formate lyase (PFL) pathway. Nonetheless, glycerol appeared to be the most abundant compound in L. plantarum F-PP samples; colorimetric analysis indicated that its average concentration in these samples was 1.05 g/L. A metabolic switch from the PFL pathway to glycerol production might occur due to acidity tolerance limitations of L. plantarum, glycerol production being associated with the release of phosphate, which can act as a buffer. Fermentation of PP by L. plantarum also led to formation of hexamine, which is a known food preservation agent. Presence of naturally formed hexamine and glycerol in food products may render using chemical additives needless.

Impact of Fermentation on the Recovery of Antioxidant Bioactive Compounds from Sea Bass Byproducts

The aim of the present research was to obtain antioxidant compounds through the fermentation of fish byproducts by bacteria isolated from sea bass viscera. To that purpose, bacteria from sea bass stomach, intestine, and colon were isolated. With the selected bacteria, growing research was undertaken, fermenting different broths prepared with sea bass meat or byproducts. After the fermentation, the antioxidant activity, phenolic acids, and some proteins were evaluated. The main phenolic acids obtained were DL-3-phenyl-lactic acid and benzoic acid at a maximum concentration of 466 and 314 ppb, respectively. The best antioxidant activity was found in the extracts obtained after the fermentation of fish byproducts broth by bacteria isolated from the colon (6502 μM TE) and stomach (4797 μM TE). Moreover, a positive correlation was found between phenolic acids obtained after the fermentation process and the antioxidant activity of the samples. It was also concluded that the lactic acid bacteria isolated from sea bass had an important proteolytic capacity and were able to synthesize phenolic acids with antioxidant capacity. This work has shown the relevance of fermentation as a useful tool to valorize fish byproducts, giving them an added economic value and reducing their environmental impact.

Probiotics, Non-Dairy Prebiotics and Postbiotics in Nutrition

The review covers achievements and developments in the field of probiosis and prebiosis originating from sources other than dairy sources, mainly from plant material like cereals. The actual definitions of probiotic microorganisms, prebiotic, and postbiotic compounds and functional food are discussed. The presentation takes into account the relations between selected food components and their effect on probiotic bacteria, as well as effects on some health issues in humans. The review also focuses on the preservation of cereals using probiotic bacteria, adverse effects of probiotics and prebiotics, and novel possibilities for using probiotic bacteria in the food industry.

Control of Aflatoxigenic Molds by Antagonistic Microorganisms: Inhibitory Behaviors, Bioactive Compounds, Related Mechanisms, and Influencing Factors

Aflatoxin contamination has been causing great concern worldwide due to the major economic impact on crop production and their toxicological effects to human and animals. Contamination can occur in the field, during transportation, and also in storage. Post-harvest contamination usually derives from the pre-harvest infection of aflatoxigenic molds, especially aflatoxin-producing Aspergilli such as Aspergillusflavus and A. parasiticus. Many strategies preventing aflatoxigenic molds from entering food and feed chains have been reported, among which biological control is becoming one of the most praised strategies. The objective of this article is to review the biocontrol strategy for inhibiting the growth of and aflatoxin production by aflatoxigenic fungi. This review focuses on comparing inhibitory behaviors of different antagonistic microorganisms including various bacteria, fungi and yeasts. We also reviewed the bioactive compounds produced by microorganisms and the mechanisms leading to inhibition. The key factors influencing antifungal activities of antagonists are also discussed in this review.

A polyphasic approach to characterize Weissella cibaria and Weissella confusa strains

AIM

To study Weissella cibaria and Weissella confusa strains, lactic acid bacteria (LAB) members naturally present in food products, but not yet included in Qualified Presumption of Safety (QPS) list of European Food Safety Authority (EFSA).

METHODS AND RESULTS

We carried out a comparative genome analysis of 23 sequenced W. cibaria and 7 W. confusa genomes, in parallel with a physiological and functional characterization of several strains previously isolated from sourdough-like maize bran fermentation. The genome analysis revealed the absence of dedicated pathogenicity factors. Some putative virulence genes found in Weissella genomes were also present in other LAB strains, considered safe by EFSA and commonly used as probiotics. The physiological tests carried out on our strains corroborated the genomic results. Moreover, the following functional traits of interest to application in the food sector were identified: the majority of tested strains displayed high acidification rate, high reducing ability, production of exopolysaccharides (EPS), arabinoxylan degradation ability, growth in the presence of fructo-oligosaccharides (FOS), bile and gastric juice tolerance, and antifungal activity.

CONCLUSIONS

These results provide evidence for the possible use of selected strains of W. cibaria and W. confusa in the food sector.

SIGNIFICANCE AND IMPACT OF THE STUDY

This polyphasic study adds to the body of knowledge on the functional and applicable characteristics of these controversial species of LAB. This knowledge contributes to design new selected cultures included in the QPS list required for food applications.

Lactic Acid Bacteria as Antifungal and Anti-Mycotoxigenic Agents: A Comprehensive Review

Fungal contamination of food and animal feed, especially by mycotoxigenic fungi, is not only a global food quality concern for food manufacturers, but it also poses serious health concerns because of the production of a variety of mycotoxins, some of which present considerable food safety challenges. In today's mega-scale food and feed productions, which involve a number of processing steps and the use of a variety of ingredients, fungal contamination is regarded as unavoidable, even good manufacturing practices are followed. Chemical preservatives, to some extent, are successful in retarding microbial growth and achieving considerably longer shelf-life. However, the increasing demand for clean label products requires manufacturers to find natural alternatives to replace chemically derived ingredients to guarantee the clean label. Lactic acid bacteria (LAB), with the status generally recognized as safe (GRAS), are apprehended as an apt choice to be used as natural preservatives in food and animal feed to control fungal growth and subsequent mycotoxin production. LAB species produce a vast spectrum of antifungal metabolites to inhibit fungal growth; and also have the capacity to adsorb, degrade, or detoxify fungal mycotoxins including ochratoxins, aflatoxins, and Fusarium toxins. The potential of many LAB species to circumvent spoilage associated with fungi has been exploited in a variety of human food and animal feed stuff. This review provides the most recent updates on the ability of LAB to serve as antifungal and anti-mycotoxigenic agents. In addition, some recent trends of the use of LAB as biopreservative agents against fungal growth and mycotoxin production are highlighted.

Exploiting synergies of sourdough and antifungal organic acids to delay fungal spoilage of bread

Fungal spoilage of bread remains an unsolved issue in bread making. This work aims to identify alternative strategies to conventional preservatives in order to prevent or delay fungal spoilage of bread. The minimum inhibitory concentration (MIC) of bacterial metabolites and chemical preservatives was evaluated in vitro, and compared to their in situ activity in baking trials. Calcium propionate, sorbic acid, 3-phenyllactic acid, ricinoleic acid, and acetic acid were tested both individually and in combination at their MIC values against Aspergillus niger and Penicillium roqueforti. The combination of acetic acid with propionate and sorbate displayed additive effects against the two fungi. For these reasons, we introduced sourdough fermentation with specific strains of lactobacilli, using wheat or flaxseed, in order to generate acetate in bread. A combination of Lactobacillus hammesii and propionate reduced propionate concentration required for shelf life extension of wheat bread 7-fold. Flaxseed sourdough bread fermented with L. hammesii, excluding any preservative, showed a shelf life 2 days longer than the control bread. The organic acid quantification indicated a higher production of acetic acid (33.8 ± 4.4 mM) when compared to other sourdough breads. Addition of 4% of sucrose to sourdough fermentation with L. brevis increased the mould free shelf-life of bread challenged with A. niger by 6 days. The combination of L. hammesii sourdough and the addition of ricinoleic acid (0.15% or 0.08%) prolonged the mould free shelf-life by 7-8 days for breads produced with wheat sourdoughs. In conclusion, the in vitro MIC of bacterial metabolites and preservatives matched the in situ antifungal effect. Of the different bacterial metabolites evaluated, acetic acid had the most prominent and consistent antifungal activity. The use of sourdough fermentation with selected strains able to produce acetic acid allowed reducing the use of chemical preservatives.