Characterization of antifungal metabolites produced by Lactobacillus plantarum and Lactobacillus coryniformis isolated from rice rinsed water

Effects of Konjac Glucomannan and Its Oligosaccharides on Improvement of Lactose Intolerance as Gut Prebiotics

Lactose intolerance (LI) is a widespread health issue affecting almost 70% of the world population. This study evaluates the potential prebiotic benefits of konjac glucomannan (KGM) and konjac oligogalactomannan (KOGM) in improving LI. Colonic fermentation results indicate that lactase groups of healthy subjects showed lower pH, higher lactic acid content, and lactase activity in fermentation broth compared with LI subjects. Total short-chain fatty acid (SCFAs) content reached 1.71 mmol/L in healthy subjects, whereas it was 1.49 mmol/L in LI subjects. In vivo studies demonstrated that KGM and KOGM intake reduced total cholesterol (T-CHO) and triglyceride (TG) levels in the liver and significantly increased immunoglobulin G (lgG) and immunoglobulin A (lgA) values, while KOGM inclusion led to a significant 23.04% increase in serum free fatty acid (FFA) levels compared to the Blank group (p < 0.05). Furthermore, ileal tissue analysis revealed a marked increase in villus height and intestinal wall thickness (p < 0.05) as well as a decrease in crypt depth (p < 0.05). The composition and proportion of gut microbiota have improved with KGM and KOGM use, notably increasing the abundance of Lactobacillus and Lachnospiraceae_NK4A136_group, respectively (p < 0.05). Compared with the Blank group, Lactobacillus abundance increased by approximately 25.82% in the Drug group, 18.23% in the KGM group, and 8.67% in the KOGM group. These findings suggest that KGM and KOGM can be utilized as prebiotics to alleviate LI symptoms.

Widely targeted metabolomics-based analysis of the impact of L. plantarum and L. paracasei fermentation on rosa roxburghii Tratt juice

Rosa roxburghii Tratt fruits (RRT) exhibit extremely high nutritional and medicinal properties due to its unique phytochemical composition. Probiotic fermentation is a common method of processing fruits. Variations in the non-volatile metabolites and bioactivities of RRT juice caused by different lactobacilli are not well understood. Therefore, we aimed to profile the non-volatile components and investigate the impact of L. plantarum fermentation (LP) and L. paracasei fermentation (LC) on RRT juice (the control, CG). There were both similarities and differences in the effects of LP and LC on RRT juice. Both of the two strains significantly increased the content of total phenolic, total flavonoid, and some bioactive compounds such as 2-hydroxyisocaproic acid, hydroxytyrosol and indole-3-lactic acid in RRT juice. Interestingly, compared with L. paracasei, L. plantarum showed better ability to increase the content of total phenolic and these valuable compounds, as well as certain bioactivities. The antioxidant capacity and α-glucosidase inhibitory activity of RRT juice were notably enhanced after the fermentations, whereas its cholesterol esterase inhibitory activity was reduced significantly. Moreover, a total of 1466 metabolites were identified in the unfermented and fermented RRT juices. There were 278, 251 and 134 differential metabolites in LP vs CG, LC vs CG, LC vs LP, respectively, most of which were upregulated. The key differential metabolites were classified into amino acids and their derivatives, organic acids, nucleotides and their analogues, phenolic acids and alkaloids, which can serve as potential markers for authentication and discrimination between the unfermented and lactobacilli fermented RRT juice samples. The KEGG enrichment analysis uncovered that metabolic pathways, purine metabolism, nucleotide metabolism and ABC transporters contributed mainly to the formation of unique composition of fermented RRT juice. These results provide good coverage of the metabolome of RRT juice in both unfermented and fermented forms and also provide a reference for future research on the processing of RRT or other fruits.

Impact of Fermentation on the Phytochemical Profile and Bioactivity Characteristics of Aqueous Matricaria recutita L. Root Extracts

While the flowers of Matricaria recutita L., German chamomile, are widely used for medicinal and cosmetic purposes, little is known about its roots, which are used in complementary medicine for the preparation of aqueous fermented extracts for the treatment of cramps and anxiety. To broaden the understanding of the active principles involved, a model fermentation approach was developed and fermentates were compared to commercially manufactured tinctures. Coumarins and hydroxycinnamates were among the major secondary metabolites characterized using HPLC-MSn. After six months of fermentation and storage, low-molecular organic acids were detected by GC-MS. Fermentation contributed to the stabilization of antioxidant and radical scavenging activities, which were in a range of about 8-10 mg gallic acid equivalents/g dry weight and 20-24 mg trolox equivalents/g dry weight, determined by Folin-Ciocalteu and DPPH assays, respectively. In addition, antibacterial activities of the extracts against Gram-positive and -negative bacteria increased during the first week of fermentation. Fermentates were neither cytotoxic nor pro- or anti-inflammatory. Thus, fermentation of chamomile roots is a suitable method for the safe production of biofunctional aqueous chamomile root extracts that remain stable without the addition of synthetic preservatives.

Discovery of two novel bioactive algicidal substances from Brevibacillus sp. via metabolomics profiling and back-validation

Identifying potent bacterial algicidal agents is essential for the development of effective, safe, and economically viable algaecides. Challenges in isolating and purifying these substances from complex secretions have impeded progress in this field. Metabolomics profiling, an efficient strategy for identifying metabolites, was pioneered in identifying bacterial algicidal substances in this study. Extracellular secretions from different generations of the algicidal bacterium Brevibacillus sp. were isolated for comprehensive analysis. Specifically, a higher algicidal efficacy was observed in the secretion from Generation 3 (G3) of Brevibacillus sp. compared to Generation 1 (G1). Subsequent metabolomics profiling comparing G3 and 1 revealed 83 significantly up-regulated metabolites, of which 9 were identified as potential algicidal candidates. Back-validation highlighted the potency of 4-acetamidobutanoic acid (4-ABC) and 8-hydroxyquinoline (8-HQL), which exhibited robust algicidal activity with 3d-EC50 values of 6.40 mg/L and 92.90 µg/L, respectively. These substances disrupted photosynthetic activity in M. aeruginosa by ceasing electron transfer in PSⅡ, like the impact exerted by Brevibacillus sp. secretion. These findings confirmed that 4-ABC and 8-HQL were the main algicidal components derived from Brevibacillus sp.. Thus, this study presents a streamlined strategy for identifying bacterial algicidal substances and unveils two novel and highly active algicidal substances. ENVIRONMENTAL IMPLICATION: Harmful cyanobacterial blooms (HCBs) pose significant environmental problems and health effects to humans and other organisms. The increasing frequency of HCBs has emerged as a pressing global concern. Bacterial-derived algicidal substances are expected to serve as effective, safe, and economically viable algaecides against HCBs. This study presents a streamlined strategy for identifying bacterial algicidal substances and unveils two novel substances (4-ABC and 8-HQL). These two substances demonstrate remarkable algicidal activity and disrupt the photosynthetic system in M. aeruginosa. They hold potential as prospective algaecides for addressing HCBs.

The Effect of Maternal Probiotic or Synbiotic Supplementation on Sow and Offspring Gastrointestinal Microbiota, Health, and Performance

The increasing prevalence of antimicrobial-resistant pathogens has prompted the reduction in antibiotic and antimicrobial use in commercial pig production. This has led to increased research efforts to identify alternative dietary interventions to support the health and development of the pig. The crucial role of the GIT microbiota in animal health and performance is becoming increasingly evident. Hence, promoting an improved GIT microbiota, particularly the pioneer microbiota in the young pig, is a fundamental focus. Recent research has indicated that the sow's GIT microbiota is a significant contributor to the development of the offspring's microbiota. Thus, dietary manipulation of the sow's microbiota with probiotics or synbiotics, before farrowing and during lactation, is a compelling area of exploration. This review aims to identify the potential health benefits of maternal probiotic or synbiotic supplementation to both the sow and her offspring and to explore their possible modes of action. Finally, the results of maternal sow probiotic and synbiotic supplementation studies are collated and summarized. Maternal probiotic or synbiotic supplementation offers an effective strategy to modulate the sow's microbiota and thereby enhance the formation of a health-promoting pioneer microbiota in the offspring. In addition, this strategy can potentially reduce oxidative stress and inflammation in the sow and her offspring, enhance the immune potential of the milk, the immune system development in the offspring, and the sow's feed intake during lactation. Although many studies have used probiotics in the maternal sow diet, the most effective probiotic or probiotic blends remain unclear. To this extent, further direct comparative investigations using different probiotics are warranted to advance the current understanding in this area. Moreover, the number of investigations supplementing synbiotics in the maternal sow diet is limited and is an area where further exploration is warranted.

The potential of postbiotics as a novel approach in food packaging and biopreservation: a systematic review of the latest developments

Metabolic by-products are part of the so-called postbiotics of probiotics and other beneficial microorganisms, particularly lactic acid bacteria, which have gained popularity as a feasible alternative to improving food quality and safety. Postbiotics in dry and liquid forms can be easily integrated into food formulations and packaging materials, exhibiting antimicrobial and antioxidant effects owing to the presence of multiple antimicrobials, such as organic acids, bacteriocins, exopolysaccharides and bioactive peptides. Postbiotics can thus control the growth of pathogens and spoilage microorganisms, thereby extending the shelf life of food products. Because of their ability to be easily manufactured without requiring extensive processing, postbiotics are regarded as a safer and more sustainable alternative to synthetic preservatives, which can have negative environmental consequences. Additionally, food manufacturers can readily adopt postbiotics in food formulations without significant modifications. This systematic review provides an in-depth analysis of studies on the use of postbiotics in the biopreservation and packaging of a wide range of food products. The review evaluates and discusses the types of microorganisms, postbiotics preparation and modification techniques, methods of usage in dairy products, meat, poultry, seafood, fruits, vegetables, bread, and egg, and their effects on food quality and safety.

Agonistic antibacterial potential of Loigolactobacillus coryniformis BCH-4 metabolites against selected human pathogenic bacteria: An in vitro and in silico approach

Lactic acid bacteria are known to produce numerous antibacterial metabolites that are active against various pathogenic microbes. In this study, bioactive metabolites from the cell free supernatant of Loigolactobacillus coryniformis BCH-4 were obtained by liquid-liquid extraction, using ethyl acetate, followed by fractionation, using silica gel column chromatography. The collected F23 fraction effectively inhibited the growth of pathogenic bacteria (Escherichia coli, Bacillus cereus, and Staphylococcus aureus) by observing the minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC). The evaluated values of MIC were 15.6 ± 0.34, 3.9 ± 0.59, and 31.2 ± 0.67 μg/mL and MBC were 15.6 ± 0.98, 7.8 ± 0.45, and 62.5 ± 0.23 μg/mL respectively, against the above-mentioned pathogenic bacteria. The concentration of F23 fraction was varying from 1000 to 1.9 μg/mL. Furthermore, the fraction also exhibited sustainable biofilm inhibition. Using the Electrospray Ionization Mass Spectrometry (ESI-MS/MS), the metabolites present in the bioactive fraction (F23), were identified as phthalic acid, myristic acid, mangiferin, 16-hydroxylpalmatic acid, apigenin, and oleandomycin. By using in silico approach, docking analysis showed good interaction of identified metabolites and receptor proteins of pathogenic bacteria. The present study suggested Loigolactobacillus coryniformis BCH-4, as a promising source of natural bioactive metabolites which may receive great benefit as potential sources of drugs in the pharmacological sector.

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.

Extraction and characterization of bioactive secondary metabolites from lactic acid bacteria and evaluating their antifungal and antiaflatoxigenic activity

Aflatoxins are toxic carcinogens and mutagens formed by some moulds, specifically Aspergillus spp. Therefore, this study aimed to extract and identify bioactive secondary metabolites from Lactobacillus species, to evaluate their efficacy in reducing fungal growth and aflatoxin production and to investigate their toxicity. The bioactive secondary metabolites of Lactobacillus species showed variable degrees of antifungal activity, whereas L. rhamnosus ethyl acetate extract No. 5 exhibited the highest antifungal activity and, thus, was selected for further identification studies. Data revealed that L. rhamnosus ethyl acetate extract No. 5 produced various organic acids, volatile organic compounds and polyphenols, displayed antifungal activity against A. flavus, and triggered morphological changes in fungal conidiophores and conidiospores. L. rhamnosus ethyl acetate extract No. 5 at a 9 mg/mL concentration reduced AFB₁ production by 99.98%. When the effect of L. rhamnosus ethyl acetate extract No. 5 on brine shrimp mortality was studied, the extract attained a 100% mortality at a concentration of 400 µg/mL, with an IC₅₀ of 230 µg/mL. Meanwhile, a mouse bioassay was performed to assess the toxicity of L. rhamnosus ethyl acetate extract No. 5, whereas there were no harmful effects or symptoms in mice injected with L. rhamnosus ethyl acetate extract at concentrations of 1, 3, 5, 7, and 9 mg/kg body weight.

Probiotics and their postbiotics for the control of opportunistic fungal pathogens: A review

During past twenty years the opportunistic fungal infections have been emerging, causing morbidity and mortality. The fungi belonging to Aspergillus, Mucor, Rhizopus, Candida, Fusarium, Penicillium, Dermatophytes and others cause severe opportunistic fungal infections. Among these Aspergillus and Candida spp cause majority of the diseases. The continuum of fungal infections will prolong to progress in the surroundings of the growing inhabitants of immunocompromised individuals. Presently many chemical-based drugs were used as prophylactic and therapeutic agents. Prolonged usage of antibiotics may lead to some severe effect on the human health. Also, one of the major threats is that the fungal pathogens are becoming the drug resistant. There are many physical, chemical, and mechanical methods to prevent the contamination or to control the disease. Owing to the limitations that are observed in such methods, biological methods are gaining more interest because of the use of natural products which have comparatively less side effects and environment friendly. In recent years, research on the possible use of natural products such as probiotics for clinical use is gaining importance. Probiotics, one of the well studied biological products, are safe upon consumption and are explored to treat various fungal infections. The antifungal potency of major groups of probiotic cultures such as Lactobacillus spp, Leuconostoc spp, Saccharomyces etc. and their metabolic byproducts which act as postbiotics like organic acids, short chain fatty acids, bacteriocin like metabolites, Hydrogen peroxide, cyclic dipeptides etc. to inhibit these opportunistic fungal pathogens have been discussed here.

Antifungal Effect of Metabolites from a New Strain Lactiplantibacillus Plantarum LPP703 Isolated from Naturally Fermented Yak Yogurt

The antifungal effect of metabolites produced by a new strain of Lactiplantibacillus (Lpb.) plantarum LPP703, isolated from naturally fermented yak yogurt, was investigated. The results showed that Lpb. plantarum LPP703 significantly inhibited four fungal species, including Penicillium sp., Rhizopus delemar, Aspergillus flavus, and Aspergillus niger. The metabolites produced after 20 h of Lpb. plantarum LPP703 fermentation showed the highest antifungal activity against Penicillium sp. Compared with the control group, the Lpb. plantarum LPP703 metabolites-treated Penicillium sp. spores were stained red by propidium iodide, indicating that the cell membrane of the fungal spores was damaged. Moreover, the antifungal effect of the Lpb. plantarum LPP703 metabolites on Penicillium sp. was not changed after heating or treatment with various proteases, but showed a sharp decrease when the pH value was regulated to 5.0 or above. The oleamide, trans-cinnamic acid, and citric acid were the three most abundant in the Lpb. plantarum LPP703 metabolites. Molecular docking predicated that the oleamide interacted with the active site of lanosterol 14-alpha-demethylase (CYP51, a crucial enzyme for fungal membrane integrity) through hydrogen bonds and had the lowest docking score, representing the strongest binding affinity to CYP51. Taken together, the metabolites from a new strain of Lpb. plantarum, LPP703, had potent antifungal activity against Penicillium sp., which might be associated with the damage of the active ingredient to fungal membrane integrity. This study indicated that Lpb. plantarum LPP703 and its metabolites might act as biological control agents to prevent fungal growth in the food industry.

Lactobacillus plantarum and Deoxynivalenol Detoxification: A Concise Review

ABSTRACT

Mycotoxins are toxic secondary fungal metabolites that contaminate feeds, and their levels remain stable during feed processing. The economic impact of mycotoxins on animal production happens mainly due to losses related to direct effects on animal health and trade losses related to grain rejection. Deoxynivalenol (DON) is a trichothecene mycotoxin that has contaminated approximately 60% of the grains worldwide. Ingestion of DON induces many toxic effects on human and animal health. Detoxification strategies to decrease DON levels in food and feeds include physical and chemical methods; however, they are not very effective when incorporated into the industrial production process. A valuable alternative to achieve this aim is the use of lactic acid bacteria. These bacteria can control fungal growth and thus overcome DON production or can detoxify the mycotoxin through adsorption and biotransformation. Some Lactobacillus spp. strains, such as Lactobacillus plantarum, have demonstrated preventive effects against DON toxicity in poultry and swine. This beneficial effect is associated with a binding capacity of lactic acid bacteria cell wall peptidoglycan with mycotoxins. Moreover, several antifungal compounds have been isolated from L. plantarum supernatants, including lactic, acetic, caproic, phenyl lactic, 3-hydroxylated fatty, and cyclic dipeptide acids. Biotransformation of DON by L. plantarum into other products is also hypothesized, but the mechanism remains unknown. In this concise review, we highlight the use of L. plantarum as an alternative approach to reduce DON levels and toxicity. Although the action mechanism of L. plantarum is still not fully understood, these bacteria are a safe, efficient, and low-cost strategy to reduce economic losses from mycotoxin contamination cases.

HIGHLIGHTS

The Antibacterial and Larvicidal Potential of Bis-(2-Ethylhexyl) Phthalate from Lactiplantibacillus plantarum

Lactic acid bacteria produce a variety of antibacterial and larvicidal metabolites, which could be used to cure diseases caused by pathogenic bacteria and to efficiently overcome issues regarding insecticide resistance. In the current study, the antibacterial and larvicidal potential of Bis-(2-ethylhexyl) phthalate isolated from Lactiplantibacillus plantarum BCH-1 has been evaluated. Bioactive compounds were extracted by ethyl acetate and were fractionated by gradient column chromatography from crude extract. Based on FT-IR analysis followed by GC-MS and ESI-MS/MS, the active compound was identified to be Bis-(2-ethylhexyl) phthalate. Antibacterial potential was evaluated by disk diffusion against E. coli (12.33 ± 0.56 mm inhibition zone) and S. aureus (5.66 ± 1.00 mm inhibition zone). Larvicidal potency was performed against Culex quinquefasciatus Say larvae, where Bis-(2-ethylhexyl) phthalate showed 100% mortality at 250 ppm after 72 h with LC50 of 67.03 ppm. Furthermore, after 72 h the acetylcholinesterase inhibition was observed as 29.00, 40.33, 53.00, 64.00, and 75.33 (%) at 50, 100, 150, 200, and 250 ppm, respectively. In comet assay, mean comet tail length (14.18 ± 0.28 μm), tail DNA percent damage (18.23 ± 0.06%), tail movement (14.68 ± 0.56 µm), comet length (20.62 ± 0.64 µm), head length (23.75 ± 0.27 µm), and head DNA percentage (39.19 ± 0.92%) were observed at 250 ppm as compared to the control. The current study for the first time describes the promising antibacterial and larvicidal potential of Bis-(2-ethylhexyl) phthalate from Lactiplantibacillus plantarum that would have potential pharmaceutical applications.

Organic Acids Secreted by Lactobacillus spp. Isolated from Urine and Their Antimicrobial Activity against Uropathogenic Proteus mirabilis

The natural microbiota of the urinary tract includes Lactobacillus spp., which secrete molecules with antimicrobial properties and have antagonistic activity against many pathogens. This paper focuses on the antibacterial effect of Lactobacillus strains isolated from urine against clinical strains of Proteus mirabilis isolated from kidney stones and from urine with coexisting urolithiasis. The study involved analyzing the main antimicrobial molecules secreted by Lactobacillus. In order to indicate which agent had the strongest antimicrobial effect, the supernatants were made alkaline and treated with catalase and high temperature. Both treated and untreated supernatants were analyzed for their activity. Exposing uropathogens to all untreated cell-free supernatants of Lactobacillus significantly reduced their growth, and it was established that these properties were related to organic acid secretion by these strains. Using LC–MS/MS and spectrophotometric techniques, lactic, citric, and succinic acids were determined qualitatively and quantitatively. The influence of these acids on the P. mirabilis growth and biofilm formation and their influence on membrane permeability were also investigated. The results indicate that organic acids secreted by Lactobacillus strains have a high antibacterial potential and could be used as novel agents in the treatment of urinary tract infections caused by P. mirabilis.

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.

Ultra-Performance Liquid Chromatography-Mass Spectrometry-Based Untargeted Metabolomics Reveals the Key Potential Biomarkers for Castor Meal-Induced Enteritis in Juvenile Hybrid Grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂)

The intensification of aquaculture to help kerb global food security issues has led to the quest for more economical new protein-rich ingredients for the feed-based aquaculture since fishmeal (FM, the ingredient with the finest protein and lipid profile) is losing its acceptability due to high cost and demand. Although very high in protein, castor meal (CM), a by-product after oil-extraction, is disposed-off due to the high presence of toxins. Concurrently, the agro-industrial wastes’ consistent production and disposal are of utmost concern; however, having better nutritional profiles of these wastes can lead to their adoption. This study was conducted to identify potential biomarkers of CM-induced enteritis in juvenile hybrid-grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) alongside their growth and distal intestinal (DI) health evaluation. A total of 360 fish (initial weight = 9.13 ± 0.01g) were randomly assigned into three groups, namely, fish-meal (FM) (control), 4% CM (CM4), and 20% CM (CM20). After the 56-days feeding-trial, the DI tissues of FM, CM4, and CM20 groups were collected for metabolomics analysis. Principal components analysis and partial least-squares discriminant-analysis (PLS-DA, used to differentiate the CM20 and CM4, from the FM group with satisfactory explanation and predictive ability) were used to analyze the UPLC-MS data. The results revealed a significant improvement in the growth, DI immune responses and digestive enzyme activities, and DI histological examinations in the CM4 group than the others. Nonetheless, CM20 replacement caused DI physiological damage and enteritis in grouper as shown by AB-PAS staining and scanning electron microscopy examinations, respectively. The most influential metabolites in DI contents identified as the potential biomarkers in the positive and negative modes using the metabolomics UPLC-MS profiles were 28 which included five organoheterocyclic compounds, seven lipids, and lipid-like molecules, seven organic oxygen compounds, two benzenoids, five organic acids and derivatives, one phenylpropanoids and polyketides, and one from nucleosides, nucleotides, and analogues superclass. The present study identified a broad array of DI tissue metabolites that differed between FM and CM diets, which provides a valuable reference for further managing fish intestinal health issues. A replacement level of 4% is recommended based on the growth and immunity of fish.

Cyclo(L-Leucyl-L-Prolyl) from Lactobacillus coryniformis BCH-4 inhibits the proliferation of Aspergillus flavus: an in vitro to in silico approach

Fungal spoilage led to a considerable economic loss of foodstuff which ultimately affects public health due to mycotoxins production. Moreover, the consumption of commercial antifungal drugs creates side effects and develops antifungal resistance. To overcome these challenges, the current work was aimed to investigate novel antifungal cyclic dipeptide (CDP) from Lactobacillus coryniformis (Loigolactobacillus coryniformis) BCH-4. CDPs have flexible, cyclic, and stable conformation. The proline-based CDPs provide additional structural compatibility and bio-functional values. Keeping in view, high-performance liquid chromatography (HPLC) was performed to explore cyclo(L-Leu-L-Pro) from L. coryniformis BCH-4. The HPLC detected concentration (135 ± 7.07 mg/mL) exhibited in vitro antifungal activity of 5.66 ± 0.57 mm (inhibitory zone) against Aspergillus flavus. Based on these results, cyclo(L-Leu-L-Pro) was used as a bioprotectant for selected food samples (grapes, lemon, cashew nuts, and almonds). A significant impact of cyclo(L-Leu-L-Pro) was observed in contrast with MRS broth (control) and cell-free supernatant. In silico molecular docking analysis of this CDP was carried out against FAD glucose dehydrogenase, dihydrofolate reductase, and urate oxidase of A. flavus as target proteins. Among these proteins, FAD glucose dehydrogenase exerted strong interactions with cyclo(L-Leu-L-Pro) having S-score of  - 8.21. The results evaluated that the detected CDP has strong interactions with selected proteins, causing excellent growth inhibition of A. flavus. Therefore, cyclo(L-Leu-L-Pro) could be used as a potent bioprotectant against food-borne pathogenic fungi.

Dynamics of Bioactive Compounds during Spontaneous Fermentation of Paste Obtained from Capsicum ssp.-Stage towards a Product with Technological Application

Six cultivars of chili (Cherry, Bulgarian Chilli, Cayenne, Fatalii, Habanero, and Carolina Reaper) from two species (Capsicum annuum and Capsicum chinense) have been studied. Anaerobic, spontaneous fermentation of pure chili paste was conducted for 21 days at 20 °C. The unfermented (UCP) and fermented chili pastes (FCP) were both subjected to physicochemical and microbiological characterization consisting of capsaicinoid, ascorbic acid, short-chain organic acids, phenolic compounds, and simple sugars analysis. Cell viability for Lactic Acid Bacteria (LAB) and Leuconostoc was determined before and after fermentation. Results indicate that capsaicinoids are very stable compounds, as notable differences between unfermented and fermented samples could not be seen. Carolina Reaper and Fatalii cultivars were amongst the most pungent, whereas Cherry, Cayenne, and Bulgarian types were low to moderate in pungency. Average loss of total ascorbic acid was 19.01%. Total phenolic compounds ranged between 36.89−195.43 mg/100 g for the fresh fruits and 35.60−180.40 mg/100 g for the fermented product. Losses through fermentation were not significant (p < 0.05). Plate counts indicated low initial numbers for LAB in the fresh samples, values ranging between 50−3700 CFU/g (colony-forming units). After fermentation, day 21, concentration of LAB (3.8 × 106−6.2 × 108 CFU/g) was high in all samples. Fermented chilies paste with enhanced biochemical and bacterial properties might further be used in the technology of vegetable (brining) or meat (curing) products, processes that generally involve the fermenting activity of different microorganisms, especially (LAB). Thus, the purpose of this research was the investigation of biochemical and microbial transformations that naturally occur in fermented chilies with a future perspective towards technological applications in cured meat products.

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.

Lactobacillus plantarum metabolites reduce deoxynivalenol toxicity on jejunal explants of piglets

The deterioration of food and feed stuffs and toxic intestinal effects due to fungal colonization and concomitant production of mycotoxins is an increasing concern. The development of fungi resistance to many commonly used chemical preservatives adds further alarm. Therefore, effective detoxification methods would be useful in counteracting this problem. Biotransformation/adsorption of mycotoxins by lactic acid bacteria and their metabolites is a promising approach to minimize the deleterious effects of mycotoxins. The objective of the present study was to evaluate the beneficial effects of Lactobacillus plantarum metabolites in reducing deoxynivalenol intestinal toxicity. To achieve this aim, histological, morphometrical and oxidative stress analyses were performed in the intestinal mucosa of piglets exposed to deoxynivalenol alone or associated with two strains (SN1 and SN2) of L. plantarum subsp. plantarum metabolites. Metabolites were obtained after dichloromethane (D) or ethyl acetate (A) extraction. Jejunal explants were exposed to the following treatments for 2 and 4 h a) culture medium (control group); b) deoxynivalenol (DON, 10 μM); c) L. plantarum metabolites DSN1; d) L. plantarum metabolites DSN1+DON; e) L. plantarum metabolites DSN2; f) L. plantarum metabolites DSN2+DON; g) L. plantarum metabolites ASN1; h) L. plantarum metabolites ASN1+DON; i) L. plantarum metabolites ASN2; j) L. plantarum metabolites ASN2+DON. The metabolites were incubated 1 h previously to DON challenge (one and 3 h of exposure). Histological assessment showed DON-treated explants with villi fusion and atrophy, multifocal apical necrosis and cuboid or flattened enterocytes with 2 and 4 h of exposure, while LP metabolites groups individually or associated with DON remained like control. The density of goblet cells in villi and crypts was reduced in DON explants compared to control group with 2 and 4 h of exposure; on the other hand, a significant increase in this parameter was achieved in LP metabolites groups compared to DON. Morphometric evaluation showed no difference in villi height or crypts depth in any treated explants. Overall, oxidative stress response assessments showed that explants exposed to SN1 extracted with dichloromethane and ethyl acetate, and SN2 extracted with dichloromethane reduced superoxide anion production. In conclusion, L. plantarum metabolites induced beneficial effects in intestinal mucosa, reducing the toxic effects of DON on intestinal morphology and oxidative response.

Untargeted LC-QTOF-MS/MS based metabolomics approach for revealing bioactive components in probiotic fermented coffee brews

Amidst trends in non-dairy probiotic foods and functional coffees, we recently developed a fermented coffee brew containing high live counts of the probiotics Lacticaseibacillus rhamnosus GG and Saccharomyces boulardii CNCM-I745. However, probiotic fermentation did not alter levels of principal coffee bioactive components based on targeted analyses. Here, to provide therapeutic justification compared to other non-fermented coffee brews, we aimed to discover postbiotics in coffee brews fermented with L. rhamnosus GG and/or S. boulardii CNCM-I745. By using an untargeted LC-QTOF-MS/MS based metabolomics approach coupled with validated multivariate analyses, 37 differential metabolites between fermentation treatments were putatively annotated. These include the production of postbiotics such as 2-isopropylmalate by S. boulardii CNCM-I745, and aromatic amino acid catabolites (indole-3-lactate, p-hydroxyphenyllactate, 3-phenyllactate), and hydroxydodecanoic acid by L. rhamnosus GG. Overall, LC-QTOF based untargeted metabolomics can be an effective approach to uncover postbiotics, which may substantiate additional potential functionalities of probiotic fermented foods compared to their non-fermented counterparts.

Characterization of the Psychrotrophic Lactic Acid Bacterium Leuconostoc gelidum subsp. aenigmaticum LS4 Isolated from Kimchi Based on Comparative Analyses of Its Genomic and Phenotypic Properties

With the aim of developing a new food starter culture, twenty-three psychrotrophic lactic acid bacteria (LAB) were isolated from 16 kimchi samples. One strain, Leuconostoc gelidum subsp. aenigmaticum LS4, which had typical psychrotrophic characteristics, was selected, and its phenotypic and genomic properties as a starter culture were investigated. The complete genome of L. aenigmaticum LS4 consisted of one circular chromosome (1,988,425 bp) and two plasmids (19,308 bp and 11,283 bp), with a guanine–cytosine content of 36.8%. L. aenigmaticum LS4 could grow at 5 °C but not at 37 °C, and maximum cell growth was obtained at 15~25 °C. L. aenigmaticum LS4 did not show any harmful characteristics such as hemolysis, undesirable enzyme activities, biogenic amine production, or antibiotic resistance. L. aenigmaticum LS4 was investigated for its suitability for technological processes (pH, temperature and NaCl treatment). L. aenigmaticum LS4 exhibited strong antimicrobial activity caused by the production of organic acids and bacteriocin, and it produced an exopolysaccharide composed of glucose with a molecular weight of 3.7 × 10⁶ Da. Furthermore, L. aenigmaticum LS4 improved the organoleptic qualities of kimchi juice. Our results indicate that L. aenigmaticum LS4 could be used as a functional starter culture for food (vegetable or fruit) fermentation at low temperatures.

Lactococcus lactis subsp. cremoris of Plant Origin Produces Antifungal Cyclo-(Leu-Pro) and Tetradecanoic Acid

The antifungal cyclo-depeptide and the fatty acid were isolated and purified from an indigenous strain of Lactococcus lactis subsp. cremoris. Maximal activity was observed at pH 5.5 and 6.5, and at 30 °C under stationary conditions, which was detected in the culture supernatant 8 h post-inoculation in MRS broth until 22 h. The activity of antifungal compounds in the culture supernatant was sensitive to pH and temperature; and was protease-resistant. The antifungal compounds were concentrated by freeze-drying and ultrafiltration with activity retained in 1 kDa filtrates indicating low molecular weight metabolites. The compounds were further extracted by using different solvents amongst which, ethyl acetate provided the highest recovery. Antifungal compounds were separated on a silica gel column into two active fractions that were revealed to be tetradecanoic acid and cyclo-(Leu-Pro), a cyclic dipeptide, by GC-MS. Herein, we describe and attribute the biocontrol potential of L. lactis subsp. cremoris to the low molecular weight antifungal compounds isolated, which is the first report of their isolation from this strain. The broad antifungal spectrum of this candidate advocates further exploration of its biocontrol potential in managing fungal infections in different food and feed systems.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-020-00917-z.

In Vitro Antimicrobial and Antioxidant Activities of Lactobacillus coryniformis BCH-4 Bioactive Compounds and Determination of their Bioprotective Effects on Nutritional Components of Maize (Zea mays L.)

Lactic acid bacteria (LAB) can synthesize antimicrobial compounds (AMCs) with nutritional and bioprotective properties in crops and food products. In the current study, AMCs of Lactobacillus coryniformis BCH-4 were evaluated to control fungal spoilage in maize grains. On maize grains treated with 75%-100% (v/v) concentrated AMCs, no fungal growth was observed even after 72 h of Aspergillus flavus inoculation. Proximate analysis of treatments A1 (raw grains), A2 (A. flavus inoculated grains) and A3 (A. flavus + AMCs inoculated grains) revealed that moisture was significantly (p ≤ 0.05) high in A2 than A3 and A1. Meanwhile, protein, fat, fiber and ash contents were significantly decreased in A2 compared to A1 and A3. Moreover, β-carotene contents were not statistically different between A1 and A3, while in A2 it was significantly decreased. HPLC analysis revealed the presence of 2-oxopropanoic acid, 2-hydroxypropane-1,2,3-tricarboxylic acid, 2-hydroxybutanedioic acid, 2-hydroxypropanoic acid, propanedioic acid and butanedioic acid, which also showed antifungal activity against Aspergillus flavus. FTIR spectroscopy revealed the presence of hydroxyl, carbonyl and ester-groups along with organic and fatty acids, thereby indicating their participation in inhibitory action. Furthermore, the AMCs were found to be a good alternative to chemical preservatives, thereby not only preserving the nutritive qualities but increasing the shelf life as well.

Anticandidal activity of Lactobacillus spp. in the presence of galactosyl polyols

Yeasts have a substantial impact on the contamination and loss of food. In this study, we applied bacteria of the genus Lactobacillus as natural biopreservatives. Anticandidal strains of bacteria were selected from among 60 strains of bacteria grown which were each with nine polyols or galactosyl polyols. Polyols and galactosyl polyols can act as prebiotics for lactic acid bacteria and can enhance the antifungal properties of bacteria by affecting their metabolism. The galactosyl polyols significantly improved the anticandidal activity of most of the bacteria we tested. Based on the screening, the most promising strains of bacteria were selected, and their metabolites (both primary and secondary) and enzymatic activity were characterized in the presence of polyols and galactosyl polyols. The qualitative and quantitative content of bacterial metabolites depended both on the bacterial strain and the type of culture medium. A wide variety of antifungals produced by bacteria, such as fatty acids, hydroxy fatty acids, and other acidic products with potential antagonistic activity (phenyllactic acid or hydroxyphenyllactic acid) were detected. The bacteria produced a high concentration of phenyllactic acid in the presence of galactosyl polyols (up to 84.3 mg/L). This finding could suggest that this metabolite may have a significant impact on the antifungal properties of lactobacilli against yeast. Galactosyl polyols influenced the enzymes involved in the synthesis of fatty acids and hydroxylated fatty acids (esterase lipase, acid phosphatase, and α-glucosidase). The mechanism of the antifungal effect of lactobacilli may be based on the synergistic effect of their primary and secondary metabolites, in particular phenyllactic acid.