Applications of plant-based fermented foods and their microbes

CLI: A new protocol for the isolation of Lactic Acid Bacteria from complex plant samples

Lactic Acid Bacteria (LAB) are predominantly probiotic microorganisms and the most are Generally Recognized As Safe (GRAS). LAB inhabit in the human gut ecosystem and are largely found in fermented foods and silage. In the last decades, LAB have also has been found in plant microbiota as a new class of microbes with probiotic activity to plants. For this reason, today the scientific interest in the study and isolation of LAB for agronomic application has increased. However, isolation protocols from complex samples such as plant tissues are scarce and inefficient. In this study, we developed a new protocol (CLI, Complex samples LAB Isolation) which yields purified LAB from plants. The sensitivity of CLI protocol was sufficient to isolate representative microorganisms of LAB genera (i.e. Leuconostoc, Lactococcus and Enterococcus). CLI protocol consists on five steps: i) sample preparation and pre-incubation in 1% sterile peptone at 30 °C for 24-48 h; ii) Sample homogenization in vortex by 10 min; iii) sample serial dilution in quarter-strength Ringer solution, iv) incubation in MRS agar plates with 0.2% of sorbic acid, with 1% of CaCO3, O2 < 15%, at pH 5.8 and 37 °C for 48 h.; v) Selection of single colonies with LAB morphology and CaCO3-solubilization halo. Our scientific contribution is that CLI protocol could be used for several complex samples and represents a useful method for further studies involving native LAB.

Potential neuroprotective benefits of plant-based fermented foods in Alzheimer's disease: an update on preclinical evidence

Alzheimer's disease (AD) currently lacks effective treatments, making its prevention a critical focus. While accumulating evidence supports that plant-based fermented foods may contribute to AD prevention, the neuroprotective effect of plant-based fermented foods on AD has not been comprehensively reviewed. In this study, we conducted a systematic review of preclinical studies on the efficacy of plant-based fermented foods in AD. The literature search was based on databases including PubMed, Embase, Web of Science, and Scopus. The PICO approach was employed for report inclusion, and each report was assessed for risk of bias using the SYRCLE's RoB tool. From the analysis of 25 retrieved reports, we extracted essential details, including bibliographic information, animal models and characteristics, sources of plant-based fermented foods, dosages, administration routes, durations, and outcome measures. Our findings indicate that plant-based fermented foods may positively impact acute and long-term cognitive function, as well as beta-amyloid-mediated neurodegeneration. This review sheds light on the potential neuroprotective benefits of plant-based fermented foods for various AD-related aspects, including oxidative stress, synaptotoxicity, neuroinflammation, tau hyperphosphorylation, dysfunctional amyloidogenic pathways, and cognitive deficits, as observed in rodent models of AD. However, the small number of studies obtained from our literature search and the finding that many of them were of moderate methodological quality suggest the need for further investigation to substantiate the beneficial potential of this class of functional food for the management of AD.

Intermittent proton bursts of single lactic acid bacteria

Lactic acid bacteria are a kind of probiotic microorganisms that efficiently convert carbohydrates to lactic acids, thus playing essential roles in fermentation and food industry. While conventional wisdom often suggests continuous release of protons from bacteria during acidification, here we developed a methodology to measure the dynamics of proton release at the single bacteria level, and report on the discovery of a proton burst phenomenon, i.e., the intermittent efflux of protons, of single Lactobacillus plantarum bacteria. When placing an individual bacterium in an oil-sealed microwell, efflux and accumulation of protons consequently reduced the pH in the confined extracellular medium, which was monitored with fluorescent pH indicators in a high-throughput and real-time manner. In addition to the slow and continuous proton release behavior (as expected), stochastic and intermittent proton burst events were surprisingly observed with a typical timescale of several seconds. It was attributed to the regulatory response of bacteria by activating H+-ATPase to compensate the stochastic and transient depolarizations of membrane potential. These findings not only revealed an unprecedented proton burst phenomenon in lactic acid bacteria, but also shed new lights on the intrinsic roles of H+-ATPase in membrane potential homeostasis, with implications for both fermentation industry and bacterial electrophysiology.

Anti-inflammatory effects of a naturally lacto-fermented cucumber product on RAW 264.7 macrophages in association with increased functional ingredients

A naturally lacto-fermented cucumber product was developed for use as anti-inflammatory functional foods. To explore the anti-inflammatory characteristics, water (CWE) and ethanol extracts (CEE) from this product were selected to assess their anti-inflammatory potential on RAW 264.7 macrophages in the absence or presence of lipopolysaccharide (LPS), using four different inflammatory models. Changes in pro- (IL-1β, IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokine secretions by treated macrophages were measured using ELISA. The results showed that both CWE and CEE had strong potential to inhibit LPS-stimulated inflammation in macrophages in a repair manner. CWE had a better effect than CEE. The total phenolic, flavonoid and saponin contents in CEE were significantly (P < 0.05) correlated with IL-10 (r = 0.384, P = 0.036*) and TNF-α (r = 0.371, P = 0.043*) levels, but slightly correlated with TNF-α/IL-10 secretion ratios (r = -0.184, P = 0.359) by treated RAW 264.7 cells, respectively.

Effects of Different Lactic Acid Bacteria in Single or Mixed Form on the Fermentative Parameters and Nutrient Contents of Early Heading Triticale Silage for Livestock

Lactic acid bacteria (LAB) are excellent anaerobic fermenters that produce highly valuable grass-based animal feed containing essential nutrients. In the present study, an ensiling process was used to improve anaerobic fermentation in triticale silage under different moisture conditions with LAB. The triticale was treated with either a single bacterium or combined LAB and then vacuum-sealed. After 180 and 360 days of storage, the silage's fermentation characteristics, microbial changes and nutrient contents were analyzed. The pH of the silage was significantly lower than the control silage. There was a significant difference in the pH values between the silages treated with single or mixed LAB. The LAB treatment led to a substantial increase in lactic acid (LA), a decrease in butyric acid (BA), and marginal levels of acetic acid (AA). The LA content after the mixed LAB treatment was significantly higher than that after the single culture LAB treatment. After single or combined inoculant treatments, the LAB population in the silage increased, while the yeast and mold levels decreased. These findings suggest that the addition of LAB to silage during ensiling could enhance the nutritional quality and reduce unwanted microbial growth. The mixed LAB treatments produced silage with a significantly higher nutritional value than the single LAB treatments.

Multi-omics characterization of the microbial populations and chemical space composition of a water kefir fermentation

In recent years, the popularity of fermented foods has strongly increased based on their proven health benefits and the adoption of new trends among consumers. One of these health-promoting products is water kefir, which is a fermented sugary beverage based on kefir grains (symbiotic colonies of yeast, lactic acid and acetic acid bacteria). According to previous knowledge and the uniqueness of each water kefir fermentation, the following project aimed to explore the microbial and chemical composition of a water kefir fermentation and its microbial consortium, through the integration of culture-dependent methods, compositional metagenomics, and untargeted metabolomics. These methods were applied in two types of samples: fermentation grains (inoculum) and fermentation samples collected at different time points. A strains culture collection of ∼90 strains was established by means of culture-dependent methods, mainly consisting of individuals of Pichia membranifaciens, Acetobacter orientalis, Lentilactobacillus hilgardii, Lacticaseibacillus paracasei, Acetobacter pomorum, Lentilactobacillus buchneri, Pichia kudriavzevii, Acetobacter pasteurianus, Schleiferilactobacillus harbinensis, and Kazachstania exigua, which can be further studied for their use in synthetic consortia formulation. In addition, metabarcoding of each fermentation time was done by 16S and ITS sequencing for bacteria and yeast, respectively. The results show strong population shifts of the microbial community during the fermentation time course, with an enrichment of microbial groups after 72 h of fermentation. Metataxonomics results revealed Lactobacillus and Acetobacter as the dominant genera for lactic acid and acetic acid bacteria, whereas, for yeast, P. membranifaciens was the dominant species. In addition, correlation and systematic analyses of microbial growth patterns and metabolite richness allowed the recognition of metabolic enrichment points between 72 and 96 h and correlation between microbial groups and metabolite abundance (e.g., Bile acid conjugates and Acetobacter tropicalis). Metabolomic analysis also evidenced the production of bioactive compounds in this fermented matrix, which have been associated with biological activities, including antimicrobial and antioxidant. Interestingly, the chemical family of Isoschaftosides (C-glycosyl flavonoids) was also found, representing an important finding since this compound, with hepatoprotective and anti-inflammatory activity, had not been previously reported in this matrix. We conclude that the integration of microbial biodiversity, cultured species, and chemical data enables the identification of relevant microbial population patterns and the detection of specific points of enrichment during the fermentation process of a food matrix, which enables the future design of synthetic microbial consortia, which can be used as targeted probiotics for digestive and metabolic health.

In vitro antioxidant activity evaluation of pine nut peptides (Pinus koraiensis) fermented by Bacillus subtilis LS-45

In this study, we utilized the remarkable capabilities of Bacillus subtilis ls-45 during the fermentation process to generate pine nut peptide. Through gene sequencing, we confirmed the proficiency of Bacillus subtilis ls-45 in producing protease, thereby serving as a valuable enzymatic source for protein hydrolysis. Our investigation focused on examining the variations in amino acid types and quantities between enzymatic pine nut protein peptide (EPP) and fermented pine nut protein polypeptide (FPP). Furthermore, we conducted a comprehensive assessment of the in vitro antioxidant activities of EPP and FPP, encompassing measurements of their Hydroxyl radical scavenging rate, Total reducing capacity, Superoxide anion scavenging rate, and ABTS+ radical scavenging rate. Notably, FPP exhibited superior antioxidant capacity compared to EPP. By employing semi-inhibitory mass concentration (IC50) analysis, we determined that FPP displayed enhanced efficacy in neutralizing hazardous free radicals when compared to EPP.

Effect of fermentation with Lactobacillus fermentum FL-0616 on probiotic-rich bean powders

Plant-based diets have received considerable attention for balancing human health and environmental sustainability. This study investigated the effects of fermentation with Lactobacillus fermentum FL-0616 on probiotic-rich mung bean, chickpea and tiger skin kidney bean powders. A particle size distribution experiment showed that the particle size of probiotic-rich bean powder was significantly reduced and the specific surface area was increased. This was critical for improving the dissolution rate, wettability and dispersibility. Simultaneously, the angles of repose and slide of the fermented bean powder were significantly reduced. Scanning electron microscopy confirmed that particle size of the bean powder decreased and became more uniform after fermentation. The results of dynamic and static rheology jointly demonstrated that fermentation improved the flowability of probiotic-rich bean powder, which was related to its decreased particle size. This study provides a technical foundation for the deep processing of bean resources.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05668-5.

Mixed fermentation and electrospray drying for the development of a novel stabilized wheat germ powder containing highly viable probiotic cultures

Nondairy fermented probiotic powder was developed based on stabilized wheat germ through mixed fermentation (Lactobacillus acidophilus and Lactobacillus plantarum) and electrospraying process. In the first step, the effect of mixed fermentation on lipase and lipoxygenase activity of wheat germ was investigated. The results showed a significant reduction in the activity of both enzymes (82.72% for lipase and 72% for lipoxygenase), therefore, mixed fermentation effectively stabilizes the wheat germ. In the next step, after the preparation of the solutions for drying process and investigating the physical properties (surface tension, electrical conductivity, and viscosity) of the solutions, the electrosprayability of the samples was evaluated at different conditions and revealed that 18 kV applying voltage, 0.3 flow rate, and 12 cm distance between tip to collector was the best for electrospraying the 20% solution of fermented wheat germ with morphologically most semi-uniform particles. Finally, the viability of the probiotics after drying process and during the storage at 25°C was examined. The number of initial cells counted as 14.48 ± 0.2 log cfu/g and the viability studies showed 0.55 log cfu/g decrease in the number of viable bacteria from initial count as a result of the electrospraying process. Furthermore, 7.86 ± 0.03 log cfu/g in freeze-dried and 9.05 ± 0.45 log cfu/g in electrosprayed samples survived after 70 days of storage.

Isolation and selection of sauerkraut lactic acid bacteria producing exopolysaccharides

Fermented plant-based foods, including sauerkraut, offer high nutritional and functional value. Their microflora is dominated by lactic acid bacteria which are a source of different substances with health- promoting benefits and diverse applications in the food industry. Production of exopolysaccharides (EPSs) by lactic acid bacteria attracts particular interest in the food industry due to their rheological properties. In the present study, we isolated 20 strains of lactic acid bacteria from traditional Bulgarian sauerkraut. The isolates were identified by 16S rDNA sequencing and were attributed to Lactiplantibacillus plantarum (75%) and Pediococcus pentosaceus (25%). All strains were screened for their ability to synthesize exopolysaccharides, and 6 of them proved positive. Since culture media composition and especially the carbon source is a critical factor influencing the yield of bacterial EPSs, the impact of various carbon sources on the EPSs synthesis by the selected producers was explored. The best results were obtained by using glucose and sucrose as sole carbon sources.

Asparagus cochinchinensis: A review of its botany, traditional uses, phytochemistry, pharmacology, and applications

Asparagus cochinchinensis (Lour.) Merr. (A. cochinchinensis) is a traditional herbal medicine that is used to treat constipation, fever, pneumonia, stomachache, tracheitis, rhinitis, cataract, acne, urticaria. More than 90 compounds have been identified from different structural types in A. cochinchinensis, including steroidal saponins, C21-steroides, lignans, polysaccharides, amino acids, etc. These bioactive ingredients make A. cochinchinensis remarkable for its pharmacological effects on anti-asthma, anti-inflammatory, anti-oxidation, anti-tumor, improving Alzheimer’s disease, neuroprotection, gut health-promoting and so on. Moreover, A. cochinchinensis also plays an important role in food, health product, cosmetic, and other fields. This review focused on the research publications of A. cochinchinensis and aimed to summarize the advances in the botany, traditional uses, phytochemistry, pharmacology, and applications which will provide reference for the further studies and applications of A. cochinchinensis.

Metabolite Pattern Derived from Lactiplantibacillus plantarum-Fermented Rye Foods and In Vitro Gut Fermentation Synergistically Inhibits Bacterial Growth

SCOPE

Fermentation improves many food characteristics using microbes, such as lactic acid bacteria (LAB). Recent studies suggest fermentation may also enhance the health properties, but mechanistic evidence is lacking. The study aims to identify a metabolite pattern reproducibly produced during sourdough and in vitro colonic fermentation of various whole-grain rye products and how it affects the growth of bacterial species of potential importance to health and disease.

METHODS AND RESULTS

The study uses Lactiplantibacillus plantarum DSMZ 13890 strain, previously shown to favor rye as its substrate. Using LC-MS metabolomics, the study finds seven microbial metabolites commonly produced during the fermentations, including dihydroferulic acid, dihydrocaffeic acid, and five amino acid metabolites, and stronger inhibition is achieved when exposing the bacteria to a mixture of the metabolites in vitro compared to individual compound exposures.

CONCLUSION

The study suggests that metabolites produced by LAB may synergistically modulate the local microbial ecology, such as in the gut. This could provide new hypotheses on how fermented foods influence human health via diet-microbiota interactions.

Fermented Minor Grain Foods: Classification, Functional Components, and Probiotic Potential

Fermented minor grain (MG) foods often have unique nutritional value and functional characteristics, which are important for developing dietary culture worldwide. As a kind of special raw material in fermented food, minor grains have special functional components, such as trace elements, dietary fiber, and polyphenols. Fermented MG foods have excellent nutrients, phytochemicals, and bioactive compounds and are consumed as a rich source of probiotic microbes. Thus, the purpose of this review is to introduce the latest progress in research related to the fermentation products of MGs. Specific discussion is focused on the classification of fermented MG foods and their nutritional and health implications, including studies of microbial diversity, functional components, and probiotic potential. Furthermore, this review discusses how mixed fermentation of grain mixtures is a better method for developing new functional foods to increase the nutritional value of meals based on cereals and legumes in terms of dietary protein and micronutrients.

Improvement of Freeze-Dried Survival of Lactiplantibacillus plantarum Based on Cell Membrane Regulation

The cell membrane of Lactiplantibacillus plantarum is a key structure for cell survival. In this study, we aimed to improve the lyophilization resistance of L. plantarum by regulating the cell membrane structure. Unsaturated fatty acids or cell membrane-regulating substances were added during culturing to determine their effect on the composition of cell membrane fatty acids and the survival rate of the cells after freeze-drying. The results showed that Tween 80, β-carotene and melatonin increased the lyophilization survival rate of L. plantarum by 9.44, 14.53, and 18.34%, respectively. After adding a lyophilization protective agent at a concentration of 21.49% at a 1:1 ratio, a combination of Tween 80, melatonin, and β-carotene was added to regulate the cell membrane, which increased the lyophilization survival rate by 32.08–86.05%. This study proposes new research directions and ideas for improving the survival rate of probiotics for industrial production.

Identification and characterization of soybean peptides and their fractions used by Lacticaseibacillus rhamnosus Lra05

Soybean peptides were reported to promote the growth and metabolism of Lacticaseibacillus rhamnosus (L. rhamnosus) Lra05. However, the relationship between L. rhamnosus Lra05 and the characteristics of soybean peptides is still unclear. Therefore, digested soybean peptides (dPEP) after 36 h utilization by L. rhamnosus Lra05 were identified and analyzed. We found that L. rhamnosus Lra05 tends to utilize hydrophobic peptides with three to five amino acids residues, and hydrophilic peptides with more than five residues. They also prefer peptides with proline at penultimate C-terminal position or arginine at ultimate C-terminal position. Moreover, fraction 1 (F1) and fraction 7 (F7) acquired from dPEP using RP-HPLC exhibited the strongest growth and metabolism promoting effects, and the utilized characteristics of F1 and F7 were similar with those of dPEP. These results explained why soybean peptides could promote L. rhamnosus to some extent and strengthen theoretical basis for the application of soybean peptides as potential prebiotics.

Changes in the content of glucosinolates, polyphenols and carotenoids during lactic-acid fermentation of cruciferous vegetables: a mini review

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Cruciferous vegetables as fermented products has been used since ancient times.

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During fermentation of cruciferous vegetables complete fermentation of glucosinolates occur.

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Fermentation decrease the content of complex polyphenols, while increase the content of polyphenols in free form.

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Carotenoid content decrease during fermentation of cruciferous vegetables.

Cruciferous vegetables are considered functional foods because of their content of health-related compounds. They are grown and consumed in various cultures around the world. Fermentation as a preservation method for cruciferous vegetables has been used since ancient times. This process results in fermented products that have a unique flavour and odour, high bioactivity, and a distinctly different phytochemical profile than raw vegetables. In this mini review, we summarize data on changes in phytochemical content during lactic-acid fermentation of various cruciferous vegetables. The main focus was on the changes in the group of glucosinolates, polyphenols and carotenoids.

Thermosonication of Broccoli Florets Prior to Fermentation Increases Bioactive Components in Fermented Broccoli Puree

The aim of this study was to compare the effects of thermosonication (18 kHz at 60 °C for 7 min) pre-treatment with thermal treatment alone (60 °C for 7 min) of broccoli florets prior to pureeing and fermentation on selected bioactive components of fermented broccoli puree. Both thermal and thermosoncation pre-treatments significantly increased the rate of acidification of broccoli puree compared to control untreated broccoli puree, with the time to reach pH 4 being 8.25, 9.9, and 24 h, respectively, for thermally treated, thermosonicated, and control samples. The highest sulforaphane yield of 7268 µmol/kg dry weight (DW) was observed in the thermosonicated samples, followed by 6227 µmol/kg DW and 3180 µmol/kg DW in the thermally treated and untreated samples, respectively. The measurable residual glucoraphanin content was 1642 µmol/kg DW, 1187 µmol/kg DW, and 1047 µmol/kg DW, respectively, in the thermonsonicated, thermally pre-treated, and control fermented samples, indicating that pre-treatment specially by thermosonication increases the extractability of glucoraphanin. The higher sulforaphane yield in the thermosonicated and thermally pre-treated samples could be due to increased extractability and accessibility of glucoraphanin and interaction with myrosinase in addition to the inactivation of epthiospecifier protein (ESP), which directs conversion away from sulforaphane into sulforaphane nitrile.

Fermented Myriophyllum aquaticum and Lactobacillus plantarum Affect the Distribution of Intestinal Microbial Communities and Metabolic Profile in Mice

This research explores the effects of fermented Myriophyllum aquaticum (F) and Lactobacillus plantarum BW2013 (G) as new feed additives on the gut microbiota composition and metabolic profile of mice. Crude protein (p = 0.045), lipid (p = 0.000), and ash (p = 0.006) contents in Myriophyllum aquaticum (N) were improved, whereas raw fiber (p = 0.031) content was decreased after solid-state fermentation by G. Mice were fed with no additive control (CK), 10%N (N), 10%N + G (NG), 10%F (F), and 10%F + G (FG). High-throughput sequencing results showed that, compared with the CK group, Parabacteroides goldsteinii was increased in treatment groups and that Lactobacillus delbrueckii, Bacteroides vulgatus, and Bacteroides coprocola were increased in the F and FG groups. Bacteroides vulgatus and Bacteroides coprocola were increased in the F group compared with the N group. Metabolomic results showed that vitamin A, myricetin, gallic acid, and luteolin were increased in the F group compared with the N group. Reduction in LPG 18:1 concentration in the N and F groups could be attenuated or even abolished by supplementation with G. Furthermore, 9-oxo-ODA was upregulated in the FG group compared with the F group. Collectively, N, F, and G have beneficial effects on gut microbiota and metabolic profile in mice, especially intake of FG.

Integrated Microbiomic and Metabolomic Dynamics of Fermented Corn and Soybean By-Product Mixed Substrate

Microbes and their metabolites produced in fermented food have been considered as critical contributors to the quality of the final products, but the comprehensive understanding of the microbiomic and metabolomic dynamics in plant-based food during solid-state fermentation remains unclear. Here, the probiotics of Bacillus subtilis and Enterococcus faecalis were inoculated into corn and defatted soybean to achieve the two-stage solid-state fermentation. A 16S sequencing and liquid chromatography–tandem mass spectrometry were applied to investigate the dynamics of microbiota, metabolites, and their integrated correlations during fermentation. The results showed that the predominant bacteria changed from Streptophyta and Rickettsiales at 0 h to Bacillus and Pseudomonas in aerobic stage and then to Bacillus, Enterococcus, and Pseudomonas in anaerobic stage. In total, 229 notably different metabolites were identified at different fermentation times, and protein degradation, amino acid synthesis, and carbohydrate metabolism were the main metabolic pathways during the fermentation. Notably, phenylalanine metabolism was the most important metabolic pathway in the fermentation process. Further analysis of the correlations among the microbiota, metabolites, and physicochemical characteristics indicated that Bacillus spp. was significantly correlated with amino acids and carbohydrate metabolism in aerobic stage, and Enterococcus spp. was remarkably associated with amino acids metabolism and lactic acid production in the anaerobic stage. The present study provides new insights into the dynamic changes in the metabolism underlying the metabolic and microbial profiles at different fermentation stages, and are expected to be useful for future studies on the quality of fermented plant-based food.

Pediococcus acidilactici FZU106 alleviates high-fat diet-induced lipid metabolism disorder in association with the modulation of intestinal microbiota in hyperlipidemic rats

Probiotics have been proved to have beneficial effects in improving hyperlipidemia. The purpose of the current research was to investigate the ameliorative effects of Pediococcus acidilactici FZU106, isolated from the traditional brewing of Hongqu rice wine, on lipid metabolism and intestinal microbiota in high-fat diet (HFD)-induced hyperlipidemic rats. Results showed that P. acidilactici FZU106 intervention obviously inhibited the abnormal increase of body weight, ameliorated serum and liver biochemical parameters related to lipid metabolism and oxidative stress. Histopathological evaluation also showed that P. acidilactici FZU106 could significantly reduce the excessive lipid accumulation in liver caused by HFD-feeding. Furthermore, P. acidilactici FZU106 intervention significantly increased the short-chain fatty acids (SCFAs) levels in HFD-fed rats, which was closely related to the changes of intestinal microbial composition and metabolism. Intestinal microbiota profiling by high-throughput sequencing demonstrated that P. acidilactici FZU106 intervention evidently increased the proportion of Butyricicoccus, Pediococcus, Rothia, Globicatella and [Eubacterium]_coprostanoligenes_group, and decreased the proportion of Corynebacterium_1, Psychrobacter, Oscillospira, Facklamia, Pseudogracilibacillus, Clostridium_innocuum_group, Enteractinococcus and Erysipelothrix in HFD-fed rats. Additionally, P. acidilactici FZU106 significantly regulated the mRNA levels of liver genes (including CD36, CYP7A1, SREBP-1c, BSEP, LDLr and HMGCR) involved in lipid metabolism and bile acid homeostasis. Therefore, these findings support the possibility that P. acidilactici FZU106 has the potential to reduce the disturbance of lipid metabolism by regulating intestinal microflora and liver gene expression profiles.

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Pediococcus acidilactici FZU106 protects against hyperlipidemia.

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Pediococcus acidilactici FZU106 regulates serum and liver lipid levels.

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Pediococcus acidilactici FZU106 regulates intestinal microbial composition.

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Pediococcus acidilactici FZU106 regulates lipid metabolism related genes.

Some Important Metabolites Produced by Lactic Acid Bacteria Originated from Kimchi

Lactic acid bacteria (LAB) have been used for various food fermentations for thousands of years. Recently, LAB are receiving increased attention due to their great potential as probiotics for man and animals, and also as cell factories for producing enzymes, antibodies, vitamins, exopolysaccharides, and various feedstocks. LAB are safe organisms with GRAS (generally recognized as safe) status and possess relatively simple metabolic pathways easily subjected to modifications. However, relatively few studies have been carried out on LAB inhabiting plants compared to dairy LAB. Kimchi is a Korean traditional fermented vegetable, and its fermentation is carried out by LAB inhabiting plant raw materials of kimchi. Kimchi represents a model food with low pH and is fermented at low temperatures and in anaerobic environments. LAB have been adjusting to kimchi environments, and produce various metabolites such as bacteriocins, γ-aminobutyric acid, ornithine, exopolysaccharides, mannitol, etc. as products of metabolic efforts to adjust to the environments. The metabolites also contribute to the known health-promoting effects of kimchi. Due to the recent progress in multi-omics technologies, identification of genes and gene products responsible for the synthesis of functional metabolites becomes easier than before. With the aid of tools of metabolic engineering and synthetic biology, it can be envisioned that LAB strains producing valuable metabolites in large quantities will be constructed and used as starters for foods and probiotics for improving human health. Such LAB strains can also be useful as production hosts for value-added products for food, feed, and pharmaceutical industries. In this review, recent findings on the selected metabolites produced by kimchi LAB are discussed, and the potentials of metabolites will be mentioned.

Narrowing down the number of potential plant-based probiotic candidates by successive in vitro, technological and in vivo assays

The interest on plant-based fermented food is in raise in Western countries. The aim of this study was to select interleukin (IL)-10 inducing strains for the development of potential probiotic plant-based fermented foods. Departing from a collection of 52 lactic acid bacteria (LAB) strains derived from plant material, in vitro co-culture with murine macrophages allowed us to narrow down the number of candidates to 21 strains able to induce IL-10 secretion. 14 of these strains were able to promote the production of tumour necrosis factor-α too. The capacity to induce IL-6 was used to further reduce the number of strains to 4, from which Lactiplantibacillus plantarum subsp. plantarum LpAv was selected to ferment oat and carrots. L. plantarum LpAv was able to ferment oat and carrots until reaching counts of ca. 10⁸ and 10⁹ cfu/ml. Fermented oat and carrots were orally administered to mice for 10 consecutive days and challenged with a single infective dose of Salmonella enterica serovar. Typhimurium. Counts of L. plantarum LpAv in fermented carrots were 9.23±0.05 cfu/ml and 9.27±0.01 cfu/ml, at day 1 and 10 of the feeding period. Fermented carrots were able to confer enhanced protection (80% of survival) against infection, when compared to control mice (less than 25% of survival). However, L. plantarum LpAv administered as pure culture was not able to confer protection against Salmonella infection. L. plantarum LpAv was selected among 52 plant-derived LAB and it was able to ferment oat and carrots, being only fermented carrots able to confer enhanced protection against Salmonella infection. A succession of in vitro to in vivo tests is proposed as a tool to narrow down the number of candidates when searching for potential novel probiotics from a collection of autochthonous strains.

The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods

An expert panel was convened in September 2019 by The International Scientific Association for Probiotics and Prebiotics (ISAPP) to develop a definition for fermented foods and to describe their role in the human diet. Although these foods have been consumed for thousands of years, they are receiving increased attention among biologists, nutritionists, technologists, clinicians and consumers. Despite this interest, inconsistencies related to the use of the term 'fermented' led the panel to define fermented foods and beverages as "foods made through desired microbial growth and enzymatic conversions of food components". This definition, encompassing the many varieties of fermented foods, is intended to clarify what is (and is not) a fermented food. The distinction between fermented foods and probiotics is further clarified. The panel also addressed the current state of knowledge on the safety, risks and health benefits, including an assessment of the nutritional attributes and a mechanistic rationale for how fermented foods could improve gastrointestinal and general health. The latest advancements in our understanding of the microbial ecology and systems biology of these foods were discussed. Finally, the panel reviewed how fermented foods are regulated and discussed efforts to include them as a separate category in national dietary guidelines.

Bacterial Diversity in Pickled Cowpea (Vigna unguiculata [Linn.] Walp) as Determined by Illumina MiSeq Sequencing and Culture-Dependent Methods

Pickled cowpea (Vigna unguiculata [Linn.] Walp) is a popular fermented vegetable in China that is made by spontaneous fermentation. Prior to this study, little was known about its microbial community. Eighteen pickled cowpea samples were collected in Enshi City, China, in 2018. The bacterial diversity within these samples was evaluated using a combination of high-throughput sequencing (Illumina MiSeq platform) targeting the V3-V4 region of the 16S rRNA gene sequence and culture-dependent methods. A total of 456,318 high-quality 16S rRNA gene sequence reads were obtained, and these reads were clustered into 19,712 OTUs with 97.0% similarity. The core bacterial phyla were Actinobacteria, Bacteroidetes, Proteobacteria, and Firmicutes; the core bacterial genera were Levilactobacillus, Lactiplantibacillus, Companilactobacillus, Pediococcus, Lactobacillus, Weissella, and Pseudomonas. Using the spread-plating method, 39 lactic acid bacteria (LAB) strains were isolated and identified based on the nearly complete 16S rRNA gene sequence. Of these, 37 were identified as Lactiplantibacillus plantarum group, while the other two were classified as Limosilactobacillus fermentum and Lacticaseibacillus rhamnosus. These results indicate a high relative abundance of LAB in traditional pickled cowpea, especially Lactobacillaceae species, which likely contribute to fermentation. This study would provide information on the LAB population of Pickled cowpea and indicated that the Pickled cowpea could be a good source for isolation of lactic acid bacteria.

Robustness of fermented carrot juice against Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli O157:H7

Artisanal vegetable fermentations are regaining popularity in industrialized countries, but they could be prone to contamination with foodborne pathogens. By simulating home or small-scale restaurant fermentations, we evaluated the microbiological safety of spontaneous carrot juice fermentations. Raw carrot juice was spiked with Listeria monocytogenes, Salmonella enterica subsp. enterica Typhimurium and Escherichia coli O157:H7, and the microbial dynamics were followed throughout the entire fermentation process by cultivation and amplicon sequencing. In addition, the behavior of these pathogens was also monitored after addition of raw cucumber juice and storage under refrigerated conditions to mimic post-contamination issues. Although the numbers of the pathogens increased during the first phase of the fermentation, the pathogens were not able to persist throughout the fermentation. Their numbers fell below the detection limit after 8 days of fermentation at 20 °C. Further investigation using amplicon sequencing also showed that there was no major impact on the general microbial dynamics of the spontaneous carrot juice fermentation. This indicates that the artisanal carrot juice fermentation is a robust process which resists the persistence of pathogens. More caution is needed however when mixing the final fermented product with a raw juice. When simulating pathogen post-contamination, both Salmonella enterica and Escherichia coli were able to survive in the refrigerated fermented juice up to 10 days after the fermentation. Listeria monocytogenes was detected up to 8 days in the refrigerated juice. Pasteurization of the raw juice before adding it to the fermented product is thus recommended.

Potential of Lactic Acid Bacteria Isolated From Different Forages as Silage Inoculants for Improving Fermentation Quality and Aerobic Stability

We aimed at isolating lactic acid bacteria (LAB) from different plant materials to study their crossed-fermentation capacity in silos and to find strains able to confer enhanced aerobic stability to silage. A total of 129 LAB isolates were obtained from lucerne (alfalfa), maize, sorghum, ryegrass, rice, barley, canola, Gatton panic, Melilotus albus, soy, white clover, wheat, sunflower, oat, and moha. Four Lactiplantibacillus plantarum subsp. plantarum strains (isolated from oat, lucerne, sorghum, or maize) were selected for their growth capacity. Identity (16S sequencing) and diversity (RAPD-PCR) were confirmed. Fermentative capacity (inoculated at 10⁴, 10⁵, 10⁶, 10⁷ CFU/g) was studied in maize silage and their cross-fermentation capacity was assessed in oat, lucerne, sorghum, and maize. Heterofermentative strains with the highest acetic acid production capacity conferred higher aerobic stability to maize silages. Regardless the source of isolation, L. plantarum strains, inoculated at a rate of 10⁶ CFU/g, were effective to produce silage from different plant materials. From more than 100 isolates obtained, the application of a succession of experiments allowed us to narrow down the number of potential candidates of silage inoculants to two strains. Based on the studies made, L. plantarum LpM15 and Limosilactobacillus fermentum LfM1 showed potential to be used as inoculants, however further studies are needed to determine their performance when inoculated together. The former because it positively influenced different quality parameters in oat, lucerne, sorghum, and maize silage, and the latter because of its capacity to confer enhanced aerobic stability to maize silage. The rest of the strains constitute a valuable collection of autochthonous strains that will be further studied in the future for new applications in animal or human foods.

Valorization of Vegetable Food Waste and By-Products Through Fermentation Processes

There is a general interest in finding new ways of valorizing fruit and vegetable processing by-products. With this aim, applications of industrial fermentation to improve nutritional value, or to produce biologically active compounds, have been developed. In this sense, the fermentation of a wide variety of by-products including rice, barley, soya, citrus, and milling by-products has been reported. This minireview gives an overview of recent fermentation-based valorization strategies developed in the last 2 years. To aid the designing of new bioprocesses of industrial interest, this minireview also provides a detailed comparison of the fermentation conditions needed to produce specific bioactive compounds through a simple artificial neural network model. Different applications reported have been focused on increasing the nutritional value of vegetable by-products, while several lactic acid bacteria and Penicillium species have been used to produce high purity lactic acid. Bacteria and fungi like Bacillus subtilis, Rhizopus oligosporus, or Fusarium flocciferum may be used to efficiently produce protein extracts with high biological value and a wide variety of functional carbohydrates and glycosidases have been produced employing Aspergillus, Yarrowia, and Trichoderma species. Fermentative patterns summarized may guide the production of functional ingredients for novel food formulation and the development of low-cost bioprocesses leading to a transition toward a bioeconomy model.

Biliaderis C. Fermented Cereal-based Products: Nutritional Aspects, Possible Impact on Gut Microbiota and Health Implications

Fermentation, as a process to increase the security of food supply, represents an integral part of food culture development worldwide. Nowadays, in the evolving functional food era where new sophisticated technological tools are leading to significant transformations in the field of nutritional sciences and science-driven approaches for new product design, fermentation technology is brought to the forefront again since it provides a solid foundation for the development of safe food products with unique nutritional and functional attributes. Therefore, the objective of the present review is to summarize the most recent advances in the field of fermentation processes related to cereal-based products. More specifically, this paper addresses issues that are relevant to nutritional and health aspects, including their interrelation with intestinal (gut) microbiome diversity and function, although clinical trials and/or in vitro studies testing for cereal-based fermented products are still scarce.

Lactic Fermented Fruit or Vegetable Juices: Past, Present and Future

Numerous traditional low-alcohol fermented beverages produced from fruit or vegetables are described around the world. Fruit and vegetables and lactic fermented products both present nutritional benefits, which give reasons for the recent expansion of non-dairy lactic fermented juices on the market. In addition, fruit and vegetable juices are new carriers for probiotic bacteria. Specific phenotypic traits of lactic acid bacteria (LAB) are required so that LAB can effectively grow in fruit or vegetable juices, increase their safety and improve their sensory and nutritional quality. From the diversity of microbiota of spontaneous fermentations, autochthonous starters can be selected, and their higher performance than allochthonous LAB was demonstrated. Achieving long-term storage and constant high quality of these beverages requires additional processing steps, such as heat treatment. Alternatives to conventional treatments are investigated as they can better preserve nutritional properties, extract bioactive compounds and promote the growth and metabolism of LAB. Specific processing approaches were shown to increase probiotic viability of fruit and vegetable juices. More knowledge on the metabolic activity of lactic acid bacterium consortium in fruit or vegetable juices has become a bottleneck for the understanding and the prediction of changes in bioactive compounds for functional beverages development. Hopefully, the recent developments of metabolomics and methods to describe enzymatic machinery can result in the reconstruction of fermentative pathways.