Lactobacillus Plantarum Strains Research Articles

Double-layer mucin microencapsulation enhances the stress tolerance and oral delivery of Lactobacillus plantarum B2

The delivery of beneficial bacteria to the gut microbiome holds a promise to avert and treat diseases such as ariboflavinosis. Nevertheless, adverse gastrointestinal (GI) conditions, a high concentration of reactive oxygen species (ROS), exhausted mucus layer, constant peristalsis of the gastrointestinal tract, and complex pathological microenvironment result in low oral bioavailability lead to limited intestinal colonization of probiotics and affect their related health benefits. Herein, we established a bio-based strategy of double-layer gelatin-mucin-alginate and chitosan-mucin-alginate microcapsules that endow the transplanted riboflavin (vitamin B2) over-producing strain Lactobacillus plantarum B2 with robust resistance to adverse environments and remarkable adhesiveness to the intestine. The outer gelatin (or chitosan) membrane was observed by building a gelatin-genipin (or chitosan-genipin) fluorescent complex. We demonstrated that co-encapsulating with mucin and the secondary coating of gelatin or chitosan could effectively maintain the regular surface morphology of gel beads and protect probiotics during the lyophilization process, possibly by improving the internal cross-linking and mechanical strength of the microcapsules. The encapsulated probiotic strain was endowed with strong resistance during storage, simulated gastrointestinal digestion fluid, and ROS exposure. In addition, co-embedded mucin augmented the adherence rate of L. P. B2 on the simulated intestinal mucus. Most importantly, microcapsule encapsulation not only retained the probiotic potential of L. P. B2 but also improved the B2 production during soymilk fermentation. Altogether, the encapsulation strategy can be used as an effective way to deliver explicit probiotics to the gut microbiota for the intestinal colonization of probiotics to deliver B2 in the human gut.

Assessment of Starters of Lactic Acid Bacteria and Killer Yeasts: Selected Strains in Lab-Scale Fermentations of Table Olives (Olea europaea L.) cv. Leccino

Olives debittering, organoleptic quality and safety can be improved with yeasts and lactic acid bacteria (LABs) selected strain starters, that allow for better fermentation control with respect to natural fermentation. Two selected killer yeasts (Wickerhamomyces anomalus and Saccharomyces cerevisiae) and Lactobacillus plantarum strains were tested for olive (cv. Leccino) fermentation to compare different starter combinations and strategies; the aim was to assess their potential in avoiding pretreatments and the use of excessive salt in the brines and preservatives. Lactobacilli, yeasts, molds, Enterobacteriaceae and total aerobic bacteria were detected, as well as pH, soluble sugars, alcohols, organic acids, phenolic compounds, and rheological properties of olives. Sugars were rapidly consumed in the brines and olives; the pH dropped quickly, then rose until neutrality after six months. The oleuropein final levels in olives were unaffected by the treatments. The use of starters did not improve the LABs’ growth nor prevent the growth of Enterobacteriaceae and molds. The growth of undesirable microorganisms could have been induced by the availability of selective carbon source such as mannitol, whose concentration in olive trees rise under drought stress. The possible role of climate change on the quality and safety of fermented foods should be furtherly investigated. The improvement of olives’ nutraceutical value can be induced by yeasts and LABs starters due to the higher production of hydroxytyrosol.

Effect of Probiotic Lactobacillus plantarum on Streptococcus mutans and Candida albicans Clinical Isolates from Children with Early Childhood Caries.

Probiotics interfere with pathogenic microorganisms or reinstate the natural microbiome. Streptococcus mutans and Candida albicans are well-known emerging pathogenic bacteria/fungi for dental caries. In this study, three probiotic Lactobacilli strains (Lactobacillus plantarum 8014, L. plantarum 14917, and Lactobacillus salivarius 11741) were tested on S. mutans and C. albicans clinical isolates using a multispecies biofilm model simulating clinical cariogenic conditions. The ten pairs of clinical isolates of S. mutans and C. albicans were obtained from children with severe early childhood caries. Our study findings show a remarkable inhibitory effect of L. plantarum 14917 on S. mutans and C. albicans clinical isolates, resulting in significantly reduced growth of S. mutans and C. albicans, a compromised biofilm structure with a significantly smaller microbial and extracellular matrix and a less virulent microcolony structure. FurTre, plantaricin, an antimicrobial peptide produced by L. plantarum, inhibited the growth of S. mutans and C. albicans. The mechanistic assessment indicated that L. plantarum 14917 had a positive inhibitory impact on the expression of S. mutans and C. albicans virulence genes and virulent structure, such as C. albicans hypha formation. Future utilization of L. plantarum 14917 and/or its antimicrobial peptide plantaricin could lead to a new paradigm shift in dental caries prevention.

In vitro detoxification of aflatoxin B1 and ochratoxin A by lactic acid bacteria isolated from Algerian fermented foods

Wheat occupies the first place in Algerian’s diet. However, because of the risk of mycotoxin contamination, its consumption can cause serious health concern to Algerian population. This study aimed to determine the in vitro detoxification properties of lactic acid bacteria (LAB) strains toward aflatoxin B1 (AFB1) and ochratoxin A (OTA), the most prevalent mycotoxins in wheat and derived products in Algeria. Eleven LAB strains isolated from Algerian fermented foods were characterized and identified using API 50 CHL and 16S rDNA sequencing methods. In order to study the ability of LAB strains to remove AFB1 and OTA, viable and heat inactivated cells of two LAB strains (Lab-L4/al and Lab-L1) selected among the eleven isolated and identified ones, as well as of the reference strain Lactobacillus plantarum (LP) R1096 were incubated individually in Citrate Phosphate Buffer (CPB 0.1 M, pH 6 or 5) containing AFB1 and/or OTA at a concentration each of 40 ng/mL for 24 h at 25 °C. Free mycotoxin concentrations were analyzed by HPLC-FLD. The isolated LAB strains were identified as Lactococcus lactis ssp lactis 1, Lactococcus lactis ssp lactis 2 and Lactobacillus paracasei ssp paracasei using API 50 CHL kit, whereas with the molecular method, the strains were identified as Enterococcus faecium and Enterococcus durans. Both viable and nonviable cells of Lab-L4/al and Lab-L1, as well as LP R1096, were able to remove AFB1 and OTA, with efficiency varying between the strains and higher for AFB1 with nonviable cells (>50 %). Removal ability of viable Lab-L4/al and LP R1096 cells increased with a decrease in pH from 6 to 5, while pH had no effect on the amounts of mycotoxins removed by viable Lab-L1 cells. In conclusion, the tested LAB strains were able to reduce the amounts of AFB1 and OTA in vitro conditions. This result suggests that these LAB strains could be used as additives or formative agents to reduce mycotoxin levels in fermented wheat foods such as sourdough bread.

Lactic acid fermentation of banana peel using Lactobacillus plantarum : Effect of substrate concentration, inoculum concentration, and various nitrogen sources

Semeru Banana peel is an organic waste that is exclusively utilized as animal feed and does not harm the environment. The primary component of banana peels is carbohydrates, which can be used as a substrate during the fermentation process to produce lactic acid. The fermentation of banana peel flour with Lactobacillus plantarum strain FNCC 0020 was the main focus of this investigation. Variations in the concentrations of the substrate and inoculum as well as the impact of the type of nitrogen on lactic acid concentration were investigated. According to research findings, the big banana peel contains 70.52% carbs, 5.68% soluble protein, 3.115% fat, 6.74% water, 2.395% ash, and 13.38% crude fiber. While the inoculum variable was 0.5% v/v and the best substrate concentration variable was 17.5% w/v, the best lactic acid concentrations were 5.401 g/L and 8.586 g/L, respectively, as determined by HPLC (High-Performance Liquid) analysis. Banana peel flour only includes a modest amount of nitrogen (0.8295%), sulfate (0.037 grams), phosphate (1.6105%), and vitamin B1 (0.2315%), so additional nitrogen sources must be added. The production of lactic acid is shown to increase with the addition of various forms of nitrogen, with ammonium sulfate and ammonium phosphate (2:1) producing the greatest yields of 9.781 g/L and 14.255 g/L, respectively, of lactic acid, which is lower than lactic acid from yeast extract.

Production of butyric acid by different strains of Lactobacillus plantarum (Lactiplantibacillus plantarum)

The butyric acid content produced by three Lactobacillus plantarum (Lactiplantibacillus plantarum) strains (FP37, FP38 and FP48) deposited as probiotic strains was determined. The experimentation was carried out to evaluate whether the production of butyric acid was due to lipolytic activity for the presence of specific lipases or was related to the fermentation of saccharides. Therefore, the three strains were inoculated in different substrates with and without the addition of fat (tributyrin). The free butyric acid contents were determined by gas chromatography after distilling each culture medium. The results showed that butyric acid production occurred mainly in the substrates supplemented with fat and therefore it was linked to the activity of specific L. plantarum lipase. The L. plantarum FP48 strain produced the highest amount of butyric acid in fat substrates and could be a useful strain in the development of dairy products with functional properties.

Isolation, identification, and fermentation characteristics of endogenous lactic acid bacteria derived from edible mushrooms

A total of 83 acid-producing strains were isolated from fresh Lentinus edodes, Pleurotus eryngii, Flammulina velutipes, Agaricus bisporus, Pleurotus ostreatus, Pleurotus djamor, Pleurotus abalones, and Pleurotus citrinopileatus by CaCO3-MRS plate medium. These 83 strains were divided into 9 species, including 52 strains of Lactococcus lactis, 13 strains of Pediococcus pentosaceus, 8 strains of Enterococcus faecium, 3 strains of Lactococcus garvieae, 2 strains of Enterococcus casseliflavus, 2 strains of Lactobacillus plantarum, 1 strain of Enterococcus lactis, 1 strain of Pediococcus acidilactici, and 1 strain of Lactobacillus pentosus based on the catalase test, Gram staining, and 16S rDNA molecular identification. Among these P. acidilactici, P. pentosus, and L. plantarum could be used in food. P. acidilactici had a strong acid-producing capacity and fast growth rate, thus showing preferable fermentation characteristics in MRS broth and edible mushroom medium than P. pentosus and L. plantarum. In the medium of L. edodes, P. eryngii, and F. velutipes, the best sensory state can be reached within 12-24 h, among them P. eryngii had the best fermentation effect, which was characterized by uniform and bright color, moderate acidity, good flavor, and tight tissue state. This study investigated the types and fermentation characteristics of lactic acid bacteria (LAB) derived from edible mushrooms, enriched the resources of LAB suitable for the fermentation, and provided a theoretical reference for the application of LAB fermentation technology of edible mushrooms.

Individual and Collective Effect of Lactic Acid Bacteria on Staphylococcus aureus

Staphylococcus aureus, as a foodborne pathogen causing significant harm worldwide, was studied to assess the effectiveness of probiotic strains Lactobacillus casei, Lactobacillus plantarum, and Bifidobacterium bifidum individually and collectively (as consortia) in controlling its growth. The growth patterns of S. aureus were observed when co-cultured with each probiotic strain and a consortium of all three strains over 72 hours. Additionally, the antimicrobial activity of probiotic cell-free supernatants (CFS) against S. aureus was tested using the agar well diffusion method. This study underscores the potential of L. plantarum and a consortium of L. casei, L. plantarum, and B. bifidum in controlling S. aureus growth.

Molecular Characterization of Lactic Acid Producing Bacteria Isolated from Tiger nut (Cyperus esculentus L) tuber and Soybean (Glycine max L) seeds

Lactic acid-producing bacteria (LAB) are a diverse group of bacteria which play a crucial role in fermentation processes. They produce lactic acid a primary product of fermentation, by exploiting food substances like carbohydrates proteins and lipids, leading to the production of secondary metabolites such as alcohols, aldehydes, acids, esters and Sulphur. The aim of this study was to characterize lactic acid bacterial isolated from tiger nut tubers (Cyperus esculentus L) and soybean seeds (Glycine max L), using 16S rRNA gene. Lactic acid production was determined by titrimetric method from 0 to 48h. Four of the ten isolates, identified as: Lactobacillus plantarum strain AMA2A, L. fermentum strain AMA5, L. buchneri strain AMA11 and L. plantarum strain AMA14 produced percentage lactic acid of 1.27, 0.93, 0.86 and 0.92 respectively after 48h. This study has demonstrated that the lactic acid producing bacteria namely: Lactobacillus plantarum AMA2A, Lactobacillus fermentum AMA5, Lactobacillus buchneri AMA11 and Lactobacillus plantarum AMA14 could be isolated from tiger nut and soybean since these substrates contain sufficient ingredients or nutrients which serve as enabling environments for their proliferation

Evaluating the Effect of a Food-origin Lactobacillus plantarum Strain on Th17 Related Cytokines

Evaluating the Effect of a Food-origin Lactobacillus plantarum Strain on Th17 Related Cytokines

Blood profiles of African catfish Clarias gariepinus fingerlings fed diets supplemented with three strains of Lactobacillus plantarum

A 10-week feeding trial was carried out to evaluate strain-specific effects of Lactobacillus plantarum on blood profiles of African catfish Clarias gariepinus fingerlings. A catfish diet was formulated and divided into five portions (experimental diets). The first portion served as control (with no probiotic added to it, labeled as NP) while the second portion received 2.5g kg-1 multi-species commercial probiotics (CP). The third, fourth and fifth portions were the experimental diets that contained 2×109cfu/g of L. plantarum strains of ascension numbers LC333558, LC333559 and LC333560, and labeled as LP58, LP59 and LP60, respectively. Fifteen apparently healthy C gariepinus fingerlings (4.86±0.59g) were stocked in an experimental tank of 70 litres capacity, while the experimental feed was fed to the fish in triplicate tanks. Similar rearing conditions were maintained in all experimental tanks. The results showed significant (p0.05) difference between the fish fed control diet and probiotics supplementation diets in some of the haematological parameters examined. Probiotics supplementations did not affect total and differential leukocytes among different experimental groups. Except for RBC counts, fish groups fed with strains LB59 and LB60 had similar effects and appeared to have better haematological values than groups fed with LB58. Strains-specific effect of L. planatrum was also observed in creatinine levels among the experimental groups. Hence, it can be concluded that strains of L. plantarum affected some haematological parameters of C. gariepinus fingerlings positively, while dietary supplementation of L. plantarum LC333559 strain could be employed to improve haematological parameters of C. gariepinus fingerlings.

Probiotic properties of Lactobacillus plantarum and application in prebiotic gummies

The increasing demand for healthy food has led to a broad interest in developing new food products containing probiotics in recent years. In this study, the potential of probiotics and prebiotics was assessed to develop novel gummies. The results showed probiotic properties in twenty-five Lactobacillus plantarum (L. plantarum) strains derived from fermented foods, confirming them to be safe for consumers, which can tolerate the simulated gastrointestinal fluids (SGIF) to a certain extent. Additionally, the DPPH free radical ranging between 13.67 ± 0.35 to 15.98 ± 0.28 mg AAE/L was expressed as ascorbic acid equivalent (AAE). Afterward, the results showed that six mushroom polysaccharides had a proliferative effect on most potential probiotics. Besides, they could further protect the survival of L. plantarum YC-5 in the SGIF. With the protection of prebiotics, the number of viable cells in SGIF exceeded 7 log CFU/mL. The genomic analysis demonstrated that 106 genes were involved in saccharide metabolism in L. plantarum YC-5. Finally, probiotics and prebiotics were used as raw materials to prepare the gummies. The results indicated that the gummies protected the probiotic L. plantarum YC-5 with little loss of activity in the SGIF. Therefore, preparing probiotics and prebiotics as gummies could be a promising probiotic food application.

Oral immunization of mice with recombinant Lactobacillus plantarum expressing a Trichinella spiralis galectin induces an immune protection against larval challenge

BackgroundTrichinella spiralis is an important foodborne parasite that presents a severe threat to food safety. The development of an anti-Trichinella vaccine is an important step towards controlling Trichinella infection in food animals and thus ensure meat safety. Trichinella spiralis galectin (Tsgal) is a novel protein that has been identified on the surface of this nematode. Recombinant Tsgal (rTsgal) was found to participate in larval invasion of intestinal epithelium cells (IECs), whereas anti-rTsgal antibodies impeded the invasion.MethodsThe rTsgal/pSIP409- pgsA′ plasmid was constructed and transferred into Lactobacillus plantarum strain NC8, following which the in vitro biological properties of rTsgal/NC8 were determined. Five groups of mice were orally immunized three times, with a 2-week interval between immunizations, with recombinant NC8-Tsgal, recombinant NC8-Tsgal + α-lactose, empty NC8, α-lactose only or phosphate-buffered saline (PBS), respectively. The vaccinated mice were infected orally with T. spiralis larvae 2 weeks following the last vaccination. Systemic and intestinal local mucosal immune responses and protection were also assessed, as were pathological changes in murine intestine and skeletal muscle.ResultsrTsgal was expressed on the surface of NC8-Tsgal. Oral immunization of mice with rTsgal vaccine induced specific forms of serum immunoglobulin G (IgG), namely IgG1/IgG2a, as well as IgA and gut mucosal secretion IgA (sIgA). The levels of interferon gamma and interleukin-4 secreted by cells of the spleen, mesenteric lymph nodes, Peyer's patches and intestinal lamina propria were significantly elevated at 2–6 weeks after immunization, and continued to rise following challenge. Immunization of mice with the oral rTsgal vaccine produced a significant immune protection against T. spiralis challenge, as demonstrated by a 57.28% reduction in the intestinal adult worm burden and a 53.30% reduction in muscle larval burden, compared to the PBS control group. Immunization with oral rTsgal vaccine also ameliorated intestinal inflammation, as demonstrated by a distinct reduction in the number of gut epithelial goblet cells and mucin 2 expression level in T. spiralis-infected mice. Oral administration of lactose alone also reduced adult worm and larval burdens and relieved partially inflammation of intestine and muscles.ConclusionsImmunization with oral rTsgal vaccine triggered an obvious gut local mucosal sIgA response and specific systemic Th1/Th2 immune response, as well as an evident protective immunity against T. spiralis challenge. Oral rTsgal vaccine provided a prospective approach for control of T. spiralis infection.Graphical

Safety evaluation and application of lactic acid bacteria and yeast strains isolated from Sichuan broad bean paste.

Broad bean paste is one of the most popular characteristic traditional fermented bean products in China, which is prepared by mixed fermentation of a variety of microorganisms, among which lactic acid bacteria and yeast played an important role in the improvement of the fermented broad bean paste quality. However, the traditional open-air fermentation of broad bean paste brought some risks of harmful microorganisms. In this study, the safety and fermentation ability of lactic acid bacteria and yeast strains isolated from traditional broad bean paste was evaluated. The results showed that the protease activity of the strain Lactobacillus plantarum DPUL-J5 (366.73 ± 9.00 U/L) and Pichia kudriavzevii DPUY-J5 (237.18 ± 10.93 U/L) were the highest. Both strains produced little biogenic amines, and did not exhibit α-hemolytic activity or antibiotic resistance for some of the antibiotics most used in human medicine. Furthermore, the broad bean paste fermentation involving DPUL-J5 and DPUY-J5 was beneficial for accumulating higher total acid (1.69 ± 0.01 g/100 g), amino-acid nitrogen (0.85 ± 0.03 g/100 g), and more volatile flavor compounds, meanwhile, reducing the levels of biogenic amines and aflatoxin B1. Therefore, this study provided a new strategy to improve the safety and quality of traditional broad bean paste.

Metabolic and Proteomic Profiles Reveal the Response of the ASD-Associated Resistant Strain 6-1 of Lactobacillus plantarum to Propionic Acid

Autism spectrum disorder (ASD) seriously affects children's health. In our previous study, we isolated and identified a bacterium (Lactobacillus plantarum strain 6-1) that is resistant to propionic acid (PA), which has been reported to play a significant role in the formation of ASD. In order to elucidate the mechanism of the resistance to PA, this study investigated the change in the metabolic and proteomic profile of L. plantarum strain 6-1 in the presence and absence of PA. The results show that 967 and 1078 proteins were specifically identified in the absence and the presence of PA, respectively, while 616 proteins were found under both conditions. Gene ontology enrichment analysis of 130 differentially expressed proteins accumulated in the presence and absence of PA indicated that most of the proteins belong to biological processes, cellular components, and molecular functions. Pathway enrichment analysis showed a great reduction in the metabolic pathway-related proteins when this resistant bacterium was exposed to PA compared to the control. Furthermore, there was an obvious difference in protein-protein interaction networks in the presence and the absence of propionic acid. In addition, there was a change in the metabolic profile of L. plantarum strain 6-1 when this bacterium was exposed to PA compared to the control, while six peaks at 696.46, 1543.022, 1905.241, 2004.277, 2037.374, and 2069.348 m/z disappeared. Overall, the results could help us to understand the mechanism of the resistance of gut bacteria to PA, which will provide a new insight for us to use PA-resistant bacteria to prevent the development of ASD in children.

Effect of Mineral-Microbial Deodorizing Preparation on the Value of Poultry Manure as Soil Amendment.

Poultry farming involves the production of poultry manures (PMs), which, if properly managed, are excellent organic soil amendments. Poultry farms generally do not have adequate arable land, and therefore, valuable fertilizer becomes a problematic waste. During the production and storage of PMs, odorous VOCs, NH4, H2S, and potent greenhouse gases such as CH4, CO2 are emitted. It influences the productivity of poultry and negatively affects the working conditions of working staff. In the present study, mineral-microbial deodorizing preparations (MMDP) based on perlite and bentonite as well as the following microorganism strains Lactobacillus plantarum, Leuconostoc mesenteroides, Bacillus megaterium, B. subtilis, and Pseudomonas fluorescens were added to the litter of turkey broilers (TB) and egg-laying hens (LH). PMs were compared with treatments without the addition of MMDP, and maize, sunflower, and rapeseed forage crops were tested. The influence on soil parameters such as pH, EC, HAC, SBC, CEC, BS, Ntot, Ctot, and plant yield and parameter of photosynthesis, i.e., SPAD index, was tested. Soil amending with manure resulted in an increase in pH and a decrease in HAC; in addition, an increase in EC, which was counteracted by the addition of MMDP, was noted. MMDP positively affected parameters such as SBC, CEC, and BS. It was shown that PMs, with the addition of MMDP, improved crops' yield in the first year of the study, whereas this effect was not seen for the after-crop plants (lupine). The main 'added value' related to the usage of MMDP in poultry production is the improvement in the properties of PMs, which mainly had a positive effect on soil indicators.

Lactobacillus plantarum strains show diversity in biofilm formation under flow conditions

In many natural and technological applications, microbial biofilms grow under fluid flow. In this project, we investigated the influence of flow on the formation and growth of biofilms produced by gram-positive Lactobacillus plantarum strains WCFS1 and CIP104448. We used an in-house designed device based on a 48-well plate with culture volumes of 0.8 ml, and quantified total biofilm formation under static and flow conditions with flow rates 0.8, 1.6, 3.2 and 4.8 ml/h (with 1, 2, 4 and 6 volume changes per hour) using crystal violet (CV) staining, and determined the number of viable biofilm cells based on plate counts. The amount of total biofilm under flow conditions increased in the CIP 104448 strain, with significantly increased staining at the wall of the wells. However, in the WCFS1 strain, no significant difference in the amount of biofilm formed under flow and static conditions was observed. Plate counts showed that flow caused an increase in the number of viable biofilm cells for both strains. In addition, using enzyme treatment experiments, we found that for WCFS1 in the static condition, the amount of mature biofilm was declined after DNase I and Proteinase K treatment, while for flow conditions, the decline was only observed for DNase I treatment. The CIP104448 biofilms formed under both static and flow conditions only showed a decline in the CV staining after adding Proteinase K, indicating different contributions of extracellular DNA (eDNA) and proteinaceous matrix components to biofilm formation in the tested strains.

Isolation of prebiotics from wild vegetables: In vitro characterization by antioxidant assays and human adenocarcinoma cell line (HT-29)

Wild vegetables are recognized for their antioxidants, fibres, other bioactive components and consumed as a rich prebiotic source along with probiotics. Crude prebiotics were isolated from wild vegetables and extracts were treated with digestive enzymes to enrich non-digestible prebiotics. The prebiotics were used to prepare different synbiotic formulations with Lactobacillus plantarum strains, L. bulgaricus and L. lactis whereas inulin served as a positive control. These formulations were evaluated for antioxidant activities viz. lipopolysaccharide-induced cell survival assessment and microbial cell adhesion using the HT-29 cell line. All formulations showed significant antioxidant activity. L. plantarum, L. plantarum (LB-VII) and L. bulgaricus with prebiotic Emblica officinalis showed highest DPPH radical scavenging activity (≈85%). ABTS radical scavenging activity was maximum for L. plantarum (LB-VII) with E. officinalis (57%). L. bulgaricus with E. officinalis showed highest FRAP activity (≈515 μM). Cell survival was restored in presence of prebiotics and maximum was observed in L. plantarum (LB-VII) with E. officinalis (77.8%) and the highest microbial cell adhesion was 76% of L. bulgaricus with E. officinalis. Microscopic cell adhesion assay showed successful adhesion to mucus secreted by HT-29 cells. This study underlines and provides evidence for the usage of wild vegetables as a source of prebiotics.

Development of Fermented Sweet Potato Flour (Ipomoea batatas L.) Supplemented with Mackerel (Scomber scombrus) Meal-Based Biscuits.

The fermentation of sweet potato (Ipomoea batatas L.) with a strain of Lactobacillus plantarum leads to an increase in its exopolysaccharides (EPS) content which is useful for enhancing the functional properties of flour. The objective of this study was to develop healthy and nutritious meal-based biscuits from fermented sweet potato (FSP) flour supplemented with mackerel flour. Eleven formulations containing wheat flour, FSP flour, nonfermented sweet potato (NFSP) flour, and mackerel flour at different proportions defined following a mixture design were used to prepare biscuits. Physicochemical, microbiological, and sensory analyses of the different biscuits were performed. Biscuits prepared with FSP at 100% scored the lowest lipid (10.83 ± 0.97 g/100 g DM) and the highest sugar (67.43 ± 0.64 g/100 g DM) contents. The incorporation of mackerel flour in the formulation led to a significant (p < 0.05) increase in the protein and mineral contents of biscuits thus conferring an immune-boosting property to these latters. All the biscuits were of good microbiological quality independent of the formulation. The highest DPPH free radicals scavenging activity (IC50 of 1.90 and 3.41 μg/mL for ethanolic and methanolic extracts, respectively) were observed with biscuits prepared with FSP flour at 100%. The sensorial characteristics of biscuits prepared with equal proportions of wheat and FSP flours were highly appreciated by the panelists with scores close to the ones prepared with wheat flour at 100%. The results of this study demonstrate the potential of FSP flour as a substitute for wheat flour in biscuits preparation. It also suggests biscuits prepared with FSP flour supplemented with mackerel flour as a functional and immune-boosting food.

Protein hydrolysates of a probiotic strain of Lactobacillus plantarum as new promising sources of inhibitors for diabetes regulatory enzymes

Diabetes is a chronic metabolic disorder characterized by persistent hyperglycaemia. It has been classified as one of the main pathologies that promotes the most severe and fatal forms of COVID-19. Although there are nowadays synthetic molecules for the regulation of this disease, their disastrous side effects still open up prospects for the search of new and healthy molecules of therapeutic interest. This study aimed at evaluating the inhibitory effect of peptides extracts produced during the cultivation of a Lactobacillus plantarum strain with probiotic properties. The peptides extracts were obtained by thermal hydrolysis of protein extracts at 70°C or 80°C for 10, 20 and 30 min. The potential hypoglycaemic activity was examined by testing their inhibitory effect on amylolytic enzymes. Our results showed that the studied proteins hydrolysates, when used at 0.024 mg (biomass) or 0.156 mg (growth broth), were capable of total inhibition of amylolytic enzymes activity. The biomass peptides showed higher inhibition rate compared to 95% obtained with 0.050 mg of acarbose, a potent and widely used anti-diabetic inhibitory. This study clearly shows that the investigated protein hydrolysates contain interesting inhibitory peptides that deserve further investigations for their real use as bioactive inhibitors of diabetes regulating enzymes.