Three New Lactobacillus plantarum Strains in the Probiotic Toolbox against Gut Pathogen Salmonella enterica Serotype Typhimurium

Plant-based probiotic foods: current state and future trends

Abstract

Plant-based probiotic foods (PBPFs) have recently become a notable choice for many consumers. While less recognized than dairy products, these foods offer efficient alternatives for individuals with lactose intolerance, vegans, or those aiming for more sustainable dietary practices. Traditional fermented PBPFs, such as kimchi, sauerkraut, and kombucha, are part of cultures from different countries and have gained more significant popularity in recent years globally due to their peculiar flavors and health benefits. However, new plant-based probiotic products have also been studied and made available to consumers of the growing demand in this sector. Therefore, this review discusses trends in plant-based probiotic production, known benefits, and characteristics. Challenges currently faced in manufacturing, distribution, marketing, consumer acceptance, and legislation are also discussed.

Graphical abstract

Alleviating Pentatrichomonas hominis-induced damage in IPEC-J2 cells: the beneficial influence of porcine-derived lactobacilli

Pentatrichomonas hominis is a common intestinal parasitic protozoan that causes abdominal pain and diarrhea, and poses a zoonotic risk. Probiotics, known for enhancing immunity and pathogen resistance, hold promise in combating parasitic infections. This study aimed to evaluate two porcine-derived probiotics, Lactobacillus reuteri LR1 and Lactobacillus plantarum LP1, against P. hominis infections in pigs. Taxonomic identity was confirmed through 16 S rRNA gene sequencing, with L. reuteri LR1 belonging to L. reuteri species and L. plantarum LP1 belonging to L. plantarum species. Both probiotics exhibited robust in vitro growth performance. Co-culturing intestinal porcine epithelial cell line (IPEC-J2) with these probiotics significantly improved cell viability compared with the control group. Pre-incubation probiotics significantly enhanced the mRNA expression of anti-oxidative response genes in IPEC-J2 cells compared with the PHGD group, with L. reuteri LR1 and L. plantarum LP1 significantly up-regulating CuZn-SOD、CAT and Mn-SOD genes expression (p < 0.05). The anti-oxidative stress effect of L. reuteri LR1 was significantly better than that of L. plantarum LP1 (p < 0.05). Furthermore, pre-incubation with the probiotics alleviated the P. hominis-induced inflammatory response. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated IL-6、IL-8 and TNF-α gene expression(p < 0.05) compared with the PHGD group. The probiotics also mitigated P. hominis-induced apoptosis. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated Caspase3 and Bax gene expression (p < 0.05), significantly up-regulated Bcl-2 gene expression (p < 0.05) compared with the PHGD group. Among them, L. plantarum LP1 showed better anti-apoptotic effect. These findings highlight the probiotics for mitigating P. hominis infections in pigs. Their ability to enhance anti-oxidative responses, alleviate inflammation, and inhibit apoptosis holds promise for therapeutic applications. Simultaneously, probiotics can actively contribute to inhibiting trichomonal infections, offering a novel approach for preventing and treating diseases such as P. hominis. Further in vivo studies are required to validate these results and explore their potential in animal and human health.

In vitro analysis of postbiotic antimicrobial activity against Candida Species in a minimal synthetic model simulating the gut mycobiota in obesity

Gut fungal imbalances, particularly increased Candida spp., are linked to obesity. This study explored the potential of Lactiplantibacillus plantarum cell-free extracts (postbiotics) to modulate the growth of Candida albicans and Candida kefyr, key members of the gut mycobiota. A minimal synthetic gut model was employed to evaluate the effects of Lactiplantibacillus plantarum postbiotics on fungal growth in mono- and mixed cultures. Microreactors were employed for culturing, fungal growth was quantified using CFU counting, and regression analysis was used to evaluate the effects of postbiotics on fungal growth. Postbiotics at a concentration of 12.5% significantly reduced the growth of both Candida species. At 24 h, both C. albicans and C. kefyr in monocultures exhibited a decrease in growth of 0.11 log CFU/mL. In contrast, mixed cultures showed a more pronounced antifungal effect, with C. albicans and C. kefyr reductions of 0.62 log CFU/mL and 0.64 log CFU/mL, respectively. Regression analysis using the Gompertz model supported the antifungal activity of postbiotics and revealed species-specific differences in growth parameters. These findings suggest that L. plantarum postbiotics have the potential to modulate the gut mycobiota by reducing Candida growth, potentially offering a therapeutic approach for combating fungal overgrowth associated with obesity.

In Vitro Characterization of Probiotic Potential of Limosilactobacillus fermentum against Salmonella Gallinarum Causing Fowl Typhoid

Fowl typhoid, a septicaemic disease of poultry, is caused by Salmonella Gallinarum and leads to severe economic losses. The aim of the present study was to isolate, select and characterize indigenous probiotic lactobacilli with anti-Salmonella Gallinarum activity. A total 55 lactobacilli were isolated from the caeca and ileum parts of healthy chickens and identified to species level by 16S rDNA sequencing. All the isolates were initially screened for antimicrobial activity and selected isolates were further subjected to in vitro evaluation of probiotic properties. Lactobacilli isolates (n = 21) showed varying levels of activity (08-18 mm) against Salmonella Gallinarum. These selected isolates also showed tolerance to acidic conditions (pH 3 and 4). Out of these 21 isolates, 13 showed growth (>0.5 OD at 600 nm) 0.3% bile salts. Moreover, these isolates also had the ability of auto-aggregation (20.05 ± 0.62%-50.70 ± 1.40%), and co-aggregation with Salmonella Gallinarum (5.22 ± 0.21%-42.07 ± 0.70%). Results revealed that lactobacilli had a higher level of resistance to vancomycin (100%), streptomycin (100%), ciprofloxacin (95%), gentamicin (90%), doxycycline (90%), oxytetracycline (85%), and bacitracin (80%), and a lower level of resistance to penicillin (33%), erythromycin (28%), chloramphenicol (23%), fusidic acid (23%) and amoxicillin (4%). The Limosilactobacillus fermentum PC-10 and PC-76 were sensitive to most of the antibiotics. The overall results revealed that two Limosilactobacillus fermentum strains (PC-10 and PC-76) fulfill the in vitro selection criteria of probiotics, i.e, tolerance to low pH, resistance to bile salts, auto-aggregation, co-aggregation with Salmonella Gallinarum, and absence of acquired antibiotic resistance. The Limosilactobacillus fermentum PC-10 and PC-76 also inhibited the (>5 log10) growth of Salmonella Gallinarum in co-culture assay. It is concluded that Limosilactobacillus fermentum PC-10 and PC-76 may be further investigated and developed as anti-Salmonella Gallinarum probiotics for poultry.

Effects of iron deficiency and iron supplementation at the host-microbiota interface: Could a piglet model unravel complexities of the underlying mechanisms?

Iron deficiency is the most prevalent human micronutrient deficiency, disrupting the physiological development of millions of infants and children. Oral iron supplementation is used to address iron-deficiency anemia and reduce associated stunting but can promote infection risk since restriction of iron availability serves as an innate immune mechanism against invading pathogens. Raised iron availability is associated with an increase in enteric pathogens, especially Enterobacteriaceae species, accompanied by reductions in beneficial bacteria such as Bifidobacteria and lactobacilli and may skew the pattern of gut microbiota development. Since the gut microbiota is the primary driver of immune development, deviations from normal patterns of bacterial succession in early life can have long-term implications for immune functionality. There is a paucity of knowledge regarding how both iron deficiency and luminal iron availability affect gut microbiota development, or the subsequent impact on immunity, which are likely to be contributors to the increased risk of infection. Piglets are naturally iron deficient. This is largely due to their low iron endowments at birth (primarily due to large litter sizes), and their rapid growth combined with the low iron levels in sow milk. Thus, piglets consistently become iron deficient within days of birth which rapidly progresses to anemia in the absence of iron supplementation. Moreover, like humans, pigs are omnivorous and share many characteristics of human gut physiology, microbiota and immunity. In addition, their precocial nature permits early maternal separation, individual housing, and tight control of nutritional intake. Here, we highlight the advantages of piglets as valuable and highly relevant models for human infants in promoting understanding of how early iron status impacts physiological development. We also indicate how piglets offer potential to unravel the complexities of microbiota-immune responses during iron deficiency and in response to iron supplementation, and the link between these and increased risk of infectious disease.

The Detection of Potential Native Probiotics Lactobacillus spp. against Salmonella Enteritidis, Salmonella Infantis and Salmonella Kentucky ST198 of Lebanese Chicken Origin

Salmonella continues to be a major threat to public health, especially with respect to strains from a poultry origin. In recent years, an increasing trend of antimicrobial resistance (AMR) in Salmonella spp. was observed due to the misuse of antibiotics. Among the approaches advised for overcoming AMR, probiotics from the Lactobacillus genus have increasingly been considered for use as effective prophylactic and therapeutic agents belonging to the indigenous microbiota. In this study, we isolated lactobacilli from the ilea and ceca of hens and broilers in order to evaluate their potential probiotic properties. Four species were identified as Limosilactobacillusreuteri (n = 22, 45.8%), Ligilactobacillussalivarius (n = 20, 41.6%), Limosilactobacillus fermentum (n = 2, 4.2%) and Lactobacillus crispatus (n = 1, 2%), while three other isolates (n = 3, 6.25%) were non-typable. Eight isolates, including Ligilactobacillussalivarius (n = 4), Limosilactobacillusreuteri (n = 2), L. crispatus (n = 1) and Lactobacillus spp. (n = 1) were chosen on the basis of their cell surface hydrophobicity and auto/co-aggregation ability for further adhesion assays using the adenocarcinoma cell line Caco-2. The adhesion rate of these strains varied from 0.53 to 10.78%. Ligilactobacillussalivarius A30/i26 and 16/c6 and Limosilactobacillus reuteri 1/c24 showed the highest adhesion capacity, and were assessed for their ability to compete in and exclude the adhesion of Salmonella to the Caco-2 cells. Interestingly, Ligilactobacillussalivarius 16/c6 was shown to significantly exclude the adhesion of the three Salmonella serotypes, S. Enteritidis, S. Infantis and S. Kentucky ST 198, to Caco-2 cells. The results of the liquid co-culture assays revealed a complete inhibition of the growth of Salmonella after 24 h. Consequently, the indigenous Ligilactobacillussalivarius 16/c6 strain shows promising potential for use as a preventive probiotic added directly to the diet for the control of the colonization of Salmonella spp. in poultry.

Spatiotemporal bio-shielding of bacteria through consolidated geometrical structuring

The probiotic bacterium Lactobacillus plantarum is often reckoned as a ‘generalist’ for its ability to adapt and survive in diverse ecological niches. The genomic signatures of L. plantarum have shown its intricate evolutionary ancestry and dynamic lifestyles. Here, we report on a unique geometrical arrangement of the multicellular population of L. plantarum cells. Prominently, a phenomenon of the cone-shaped colony formation and V-shaped cell chaining are discovered in response to the acidic-pH environment. Moreover, subsequent cold stress response triggers an unusual cellular arrangement of consolidated bundles, which appeared to be independently governed by a small heat shock protein (HSP 1). We further report that the V-shaped L. plantarum chaining demonstrates potent antagonistic activity against Candida albicans, a pathogenic yeast, both in vitro and in a Caenorhabditis elegans co-infection model. Finally, we deduce that the multifaceted traits manifested by this probiotic bacterium is an outcome of its dynamic flexibility and cellular heterogeneity.

Probiotic and paraprobiotic derivates exhibit anti-inflammatory and genoprotective effects in induced stress

AIMS

The literature highlights the pathology of inflammation and its role in carcinogenesis, aging, and related diseases. Inflammatory processes induce oxidative stress and reduce antioxidant capacity. This study investigated the antioxidant and anti-inflammatory potential of probiotic bacteria isolated from fermented whey under conditions of induced stress.

METHODS AND RESULTS

Functional antioxidant characterization of potential probiotic bacteria Lactiplantibacillus plantarum S1 was performed under different growth conditions (aerobic, respiratory, and anaerobic) and under stress to find the conditions that yield the most effective cells. Since aerobic growth yielded the most potent cells, the free radical scavenging ability of live and heat-killed cells was measured before and after exposure to gastrointestinal conditions. For heat-killed cells and extracted probiotic metabolites, the reduction of DNA damage to immune cells was determined in the hydrogen peroxide exposure comet assay. The combination of inactivated cells and metabolites showed the best reduction in DNA damage. Finally, in the LPS inflammation model, the aforementioned probiotic metabolites significantly reduced TNF-α levels in immune cells.

CONCLUSIONS

Whey-derived potential probiotic bacteria exert antioxidant and anti-inflammatory effects, and based on this study, we propose a model combining inactivated cells and metabolites to reduce inflammatory and oxidative stress-related adverse effects.

SIGNIFICANCE AND IMPACT OF STUDY

In this study, a new probiotic model is proposed for continuous use to reduce oxidative and inflammatory stress in the gut.

Combined Inhibitory Effect of Fir (Abies alba Mill.) Honeydew Honey and Probiotic Bacteria Lactiplantibacillus plantarum on the Growth of Salmonella enterica Serotype Typhimurium

Honey is a natural food consisting mainly of sugars, enzymes, amino acids, organic acids, vitamins, minerals and aromatic substances. In addition to specific organoleptic properties, honey also has other components that contribute to its nutritional and health value. Proteins, vitamins, minerals, organic acids and phenolic compounds, the most variable components of honey, are predominantly responsible for its strong bioactive effect. Honeydew honey is a less known type of honey with outstanding antimicrobial and antioxidant properties that also demonstrates prebiotic effects and can promote the growth of probiotic bacteria. Foodborne illnesses can be prevented by using probiotic strains in combination with prebiotics. The aim of this study was for the first time to determine potential synergistic antimicrobial effect of fir (Abies alba Mill.) honeydew honey (HS) and probiotic bacteria Lactiplantibacillus plantarum on Salmonella enterica serotype Typhimurium, a primary cause of foodborne illnesses. The effect of three different samples of fir honeydew honey on the growth of L. plantarum in de Man, Rogosa and Sharpe (MRS) medium and the potential synergistic effect of HSs and L. plantarum on the growth of S. Typhimurium in the Brain Heart Infusion (BHI) medium were examined. The results indicate that concentrations of 1 and 5% of all three HS samples stimulate the growth and metabolic activity of L. plantarum, while a concentration of 10% inhibits the growth of L. plantarum. The concentration of 5% of all three HS and L. plantarum combined inhibits the growth of S. Typhimurium in BHI broth. Fir honeydew honey showed potential prebiotic properties and antimicrobial activity, both of which can synergistically enhance the probiotic efficacy of L. plantarum against S. Typhimurium To conclude, the combination of fir honeydew honey and L. plantarum represents a successful combination against S. Typhimurium and additional experiments are necessary regarding the mechanisms of their combined effect.

Comparative Lipidomic Analysis of Extracellular Vesicles Derived from Lactobacillus plantarum APsulloc 331261 Living in Green Tea Leaves Using Liquid Chromatography-Mass Spectrometry

Lactobacillus plantarum is a popular probiotic species due to its safe and beneficial effects on humans; therefore, novel L. plantarum strains have been isolated and identified from various dietary products. Given that bacteria-derived extracellular vesicles (EVs) have been considered as efficient carriers of bioactive materials and shown to evoke cellular responses effectively, L. plantarum-derived EVs are expected to efficiently elicit health benefits. Herein, we identified L. plantarum APsulloc 331261 living in green tea leaves and isolated EVs from the culture medium. We performed quantitative lipidomic analysis of L. plantarum APsulloc 331261 derived EVs (LEVs) using liquid chromatography-mass spectrometry. In comparison to L. plantarum APsulloc 331261, in LEVs, 67 of 320 identified lipid species were significantly increased and 19 species were decreased. In particular, lysophosphatidylserine(18:4) and phosphatidylcholine(32:2) were critically increased, showing over 21-fold enrichment in LEVs. In addition, there was a notable difference between LEVs and the parent cells in the composition of phospholipids. Our results suggest that the lipidomic profile of bacteria-derived EVs is different from that of the parent cells in phospholipid content and composition. Given that lipids are important components of EVs, quantitative and comparative analyses of EV lipids may improve our understanding of vesicle biogenesis and lipid-mediated intercellular communication within or between living organisms.

Determination of competition and adhesion abilities of lactic acid bacteria against gut pathogens in a whole-tissue model

In an intestinal system with a balanced microbial diversity, lactic acid bacteria (LAB) are the key element which prevents the colonization and invasion of gut pathogens. Adhesion ability is important for the colonization and competition abilities of LAB. The aim of this study was to determine the adhesion and competition abilities of LAB by using a whole-tissue model. Indigenous strains were isolated from spontaneously fermented foods like cheese and pickles. The aggregation and competition abilities of the isolates were determined, as well as their resistance to gastrointestinal conditions. Four Lactobacillus strains and one Weissella strain were found to be highly competitive against three major gut pathogens, namely Clostridium difficile, Listeria monocytogenes and Salmonella Enteritidis. Tested strains decreased the number of pathogens to below their disease-causing levels. According to the results, the numbers of C. difficile and L. monocytogenes bacteria decreased by an average of 3 log, and their adhesion rates decreased by approximately 50%. However, the number of S. Enteritidis bacteria was decreased by only 1 log compared with its initial number. We thought that the weak effect on Salmonella was due to its possession of many virulence factors. The results showed that natural isolates from sources other than human specimens like the Weissella strain in this study were quite competent when compared with the human isolates in terms of their adhesion to intestines and resistance to gastrointestinal tract conditions. It was also revealed that a whole-tissue model with all-natural layers can be successfully used in adhesion and competition tests.

In Vitro Studies on Therapeutic Potential of Probiotic Yeasts Isolated from Various Sources

The present study investigates the therapeutic properties of probiotic yeasts viz. Yarrowia lipolytica VIT-MN01, Kluyveromyces lactis VIT-MN02, Lipomyces starkeyi VIT-MN03, Saccharomycopsis fibuligera VIT-MN04 and Brettanomyces custersianus VIT-MN05. The antimutagenic activity of probiotic yeasts against the mutagens viz. Benzo[a]pyrene (B[a]P), and Sodium azide (SA) was tested. S. fibuligera VIT-MN04 showed highest antimutagenicity (75%). Binding ability on the mutagen acridine orange (AO) was tested and L. starkeyi VIT-MN03 was able to bind AO effectively (88%). The probiotic yeasts were treated with the genotoxins viz. 4-Nitroquinoline 1-Oxide (NQO) and Methylnitronitrosoguanidine (MNNG). The prominent changes in UV shift confirmed the reduction in genotoxic activity of S. fibuligera VIT-MN04 and L. starkeyi VIT-MN03, respectively. Significant viability of probiotic yeasts was noted after being exposed to mutagens and genotoxins. The adhesion capacity and anticancer activity were also assessed using Caco-2 and IEC-6 cell lines. Adhesion ability was found to be more in IEC-6 cells and remarkable antiproliferative activity was noted in Caco-2 cells compared to normal cells. Further, antagonistic activity of probiotic yeasts was investigated against S. typhimurium which was found to be more in S. fibuligera VIT-MN04 and L. starkeyi VIT-MN03. The inhibition of α-glucosidase and α-amylase activity confirmed the antidiabetic activity of probiotic yeasts. Antioxidant activity was also tested using standard assays. Therefore, based on the results, it can be concluded that probiotic yeasts can serve as potential therapeutic agents for the prevention and treatment of colon cancer, type 2 diabetes and gastrointestinal infections.

Protective Effect of Potential Probiotic Strains from Fermented Ethiopian Food against Salmonella Typhimurium DT104 in Mice

Salmonella is one of the most harmful pathogens responsible for foodborne outbreaks, illnesses and deaths. The aim of this study was to evaluate the effect of potentially probiotic strains against Salmonella Typhimurium DT104 in mice. The compatibility test among the selected potential probiotic strains (Lactobacillus plantarum K132, Lactobacillus paracasei K114 and Lactococcus lactis E124) using the cross-streaking method showed the absence of antagonism. The anti-Salmonella activities of coculture of the isolated potential probiotics in the form of mixed or single culture showed a remarkable anti-Salmonella activity with 96.50 to 100% growth inhibition. The combination of strains, which showed the highest growth inhibition rates against Salmonella Typhimurium DT104, was used to test their effect on the colonization of mice by Salmonella Typhimurium DT104. White albino male mice were pretreated with the mixed potential probiotics for 7 days and infected with Salmonella Typhimurium DT104 for 1 day. A total of 3 treatments were applied, during which the negative control group was treated with phosphate-buffered saline (PBS); a positive control group (typ) was challenged with Salmonella Typhimurium DT104 alone. The treated group (pro-typ) was pretreated with mixed potential probiotic culture and then infected with Salmonella Typhimurium DT104. The survival rate of mice and counts of Salmonella in feces were recorded. The survival rate of mice on day 21 after the oral challenge with Salmonella Typhimurium DT104 was significantly (p < 0.05) higher in the experimental pro-typ group (100% survival) compared with the positive control group (20% survival). The counts (colony-forming unit per ml) of Salmonella in feces were significantly lower (p < 0.05) for the pro-typ group compared to the typ group. The combination of potential probiotic strains was able to protect mice against Salmonella Typhimurium DT104 infection that demonstrates their potential to be used as probiotic cultures for the production of functional fermented products.

In vitro assessment of antibacterial activity from Lactobacillus spp. strains against virulent Salmonella species isolated from slaughter animals in Benin

Background and Aim:

Salmonella spp. are among the world’s leading foodborne pathogens, found naturally in the intestines of many animals. Lactic acid bacteria, mainly Lactobacillus, are a promising alternative to antibiotics for animal and human health. This study aimed to assess the in vitro antibacterial activity of Lactobacillus spp. strains against virulent Salmonella spp. isolated from slaughter animals in Benin.

Materials and Methods:

Eleven samples of raw cow’s milk, five samples of breast milk, and six infant stool samples were taken. From these samples, strains of Lactobacillus were isolated and identified. The probiotic potential of each of the identified strains was characterized, and finally in vitro antibacterial activity of these strains was evaluated against three virulent strains of Salmonella spp. and a reference strain of Salmonella Typhimurium ATCC 14028.

Results:

Out of the 22 samples collected, 20 strains of Lactobacillus spp. were isolated and identified. These strains included Lactobacillus plantarum (30%), Lactobacillus delbrueckii (25%), Lactobacillus casei (25%), Lactobacillus salivarius (15%), and Lactobacillus acidophilus (05%). Characterization of the probiotic potential of these strains showed that only 16 strains were resistant to pH=1.5. Fourteen of them were able to withstand the simulated gastric juice (pH 1.5+pepsin). The 14 probiotic strains showed very good antibacterial activity against virulent strains of Salmonella spp. with inhibition zone diameters ranging from 12.36±0.03 mm to 35.33±0.05 mm (R values>6 mm).

Conclusion:

From this study, Lactobacillus strains isolated from raw cow milk, breast milk, and infantile stool might be used as some valid candidates for probiotics. It also represents good alternatives for antibiotics in the fight against animal and human salmonellosis.

Characterization and probiotic properties of Lactobacilli from human breast milk

Several studies have reported a complex microbial community in human breast milk. This community impacts the shape of the infant gut microbiota and consequently impacts host health. Lactobacillus is an important probiotic and has many applications in the functional food industry. This study isolated and evaluated the potential probiotic bacteria from human milk. Two Lactobacillus species, L. plantarum and L. pentosus, were isolated from the breast milk of Thai women. L. pentosus HM04-22, L. pentosus HM04-3, L. plantarum HM04-80, L. plantarum HM04-88 and L. plantarum HM01-1 showed good adhesion activity (> 55%) and resistance in gastric (pH 2) and bile (pH 8) conditions. Characterization of the probiotic properties indicated that all selected Lactobacillus isolates had anti-adhesion properties against Escherichia coli and Salmonella Typhimurium. Lactobacillus isolates protected Caco-2 cells from pathogen adhesion at 25-40%. In addition, the five selected strains presented anti-inflammatory properties by reducing interleukin (IL)-8 expression at 0.14 ± 0.16 to 0.52 ± 0.117-fold. However, the strains had no effect on the expression of tight junction genes, including zona occludens (ZO)-1, occludin and claudin-1. In conclusion, five selected Lactobacillus isolates from human milk were candidates for use as probiotics to promote health. However, more tests in animal models and clinical trials need to be performed.

Viability of microencapsulated Akkermansia muciniphila and Lactobacillus plantarum during freeze-drying, storage and in vitro simulated upper gastrointestinal tract passage

Akkermansia muciniphila, an abundant member of the human gut microbiota, has been suggested as a potential next-generation probiotic. However, its high sensitivity to oxygen limits the development of dosage protocols. Here, we describe microencapsulation, in a xanthan and gellan gum matrix, and a subsequent freeze-drying protocol for A. muciniphila DSM22959. For comparison Lactobacillus plantarum subsp. plantarum ATCC14917 was microencapsulated and freeze-dried using similar protocols. Four different mixtures were tested for cryoprotective properties: sucrose 5% plus trehalose 5%; agave syrup 10%; skim milk 10%, glucose 1%, yeast extract 0.5%, and mannitol 2.5%; as well as peptone 0.1% plus sorbitol 1.2%. Milli-Q-water served as control. Only cryoprotectant solutions with high sugar or protein content significantly improved the survival of both strains during freeze-drying. Microencapsulated cells were stored aerobically or anaerobically for 1 month at 4 °C or 25 °C. Survival of A. muciniphila was significantly better when stored anaerobically at 4 °C. The survival of microencapsulated L. plantarum, was relatively stable at both temperatures under anaerobic conditions. Survival of microencapsulated cells was compared with that of free cells during in vitro simulated upper gastrointestinal tract (GIT) transit at fasted and fed state. During in vitro simulated stomach passage, encapsulation significantly improved survival and viable cells remained at relevant levels after the entire simulated upper GIT transit. In conclusion, we here report a protocol for encapsulating A. muciniphila giving acceptable storage stability and enhancing survival during in vitro simulated upper GIT transit and thus constitutes an important step towards enabling future use of this important member of the human colonic microbiota as a probiotic.

Lactobacillus plantarum with Functional Properties: An Approach to Increase Safety and Shelf-Life of Fermented Foods

Lactobacillus plantarum (widespread member of the genus Lactobacillus) is one of the most studied species extensively used in food industry as probiotic microorganism and/or microbial starter. The exploitation of Lb. plantarum strains with their long history in food fermentation forms an emerging field and design of added-value foods. Lb. plantarum strains were also used to produce new functional (traditional/novel) foods and beverages with improved nutritional and technological features. Lb. plantarum strains were identified from many traditional foods and characterized for their systematics and molecular taxonomy, enzyme systems (α-amylase, esterase, lipase, α-glucosidase, β-glucosidase, enolase, phosphoketolase, lactase dehydrogenase, etc.), and bioactive compounds (bacteriocin, dipeptides, and other preservative compounds). This review emphasizes that the Lb. plantarum strains with their probiotic properties can have great effects against harmful microflora (foodborne pathogens) to increase safety and shelf-life of fermented foods.