Plantarum Cells Research Articles

The V‐Shaped Structuring Regulated via the LuxS‐Dependent Quorum‐Sensing Pathway Is Associated With Lactiplantibacillus plantarum Survivability in Acidic Environments

ABSTRACTTolerance to acidic environments is an important adaptive feature of the probiotic bacterium Lactiplantibacillus plantarum for surviving gastrointestinal transit or food processing. Here, we report a previously uncharacterized biological process that enables a highly coordinated adaptation of this bacterium to acidic stress. We provide mechanistic evidence for the role of the V‐shaped multicellular structuring, associated with incomplete daughter cell separation, in the survival of L. plantarum cells in acidic environments. We also show that this process facilitates structured biofilm formation through the LuxS‐dependent quorum‐sensing pathway associated with autoinducer‐2 (AI‐2) production. The LuxS knockout results in compromised V‐shaped structuring and poor biofilm formation under acidic conditions, whereas exogenous supplementation of 4,5‐dihydroxy‐pentanedione (DPD), the precursor of AI‐2, to the LuxS knockout strain, restores V‐shaped structuring and biofilm formation in an acidic environment. Furthermore, we show that LuxS‐dependent V‐shaped structuring provides an extraordinary protection mode for cellular survivability in extremely acidic conditions. Consequently, we propose that the self‐generated V‐shaped structuring, regulated by LuxS, is associated with protective and coordinated multicellular behavior during adaptation to acidic stress. It is believed that this study paves the way for developing a promising platform for preserving and delivering probiotic cells to mammalian hosts by utilizing persistent geometrical structuring.

Differential alteration in Lactiplantibacillus plantarum subsp. plantarum quorum-sensing systems and reduced Candida albicans yeast survival and virulence gene expression in dual-species interaction.

Candida albicans (C. albicans) and Lactiplantibacillus plantarum subsp. plantarum (L. plantarum) are frequently identified in various niches, but their dual-species interaction, especially with C. albicans in yeast form, remains unclear. This study aimed to investigate the dual-species interaction of L. plantarum and C. albicans, including proliferation, morphology, and transcriptomes examined by selective agar plate counting, microscopy, and polymicrobial RNA-seq, respectively. Maintaining a stable and unchanged growth rate, L. plantarum inhibited C. albicans yeast cell proliferation but not hyphal growth. Combining optical microscopy and atomic force microscopy, cell-to-cell direct contact and co-aggregation with L. plantarum cells surrounding C. albicans yeast cells were observed during dual-species interaction. Reduced C. albicans yeast cell proliferation in mixed culture was partially due to L. plantarum cell-free culture supernatant but not the acidic environment. Upon polymicrobial transcriptomics analysis, interesting changes were identified in both L. plantarum and C. albicans gene expression. First, two L. plantarum quorum-sensing systems showed contrary changes, with the activation of lamBDCA and repression of luxS. Second, the upregulation of stress response-related genes and downregulation of cell cycle, cell survival, and cell integrity-related pathways were identified in C. albicans, possibly connected to the stress posed by L. plantarum and the reduced yeast cell proliferation. Third, a large scale of pathogenesis and virulence factors were downregulated in C. albicans, indicating the potential interruption of pathogenic activities by L. plantarum. Fourth, partial metabolism and transport pathways were changed in L. plantarum and C. albicans. The information in this study might aid in understanding the behavior of L. plantarum and C. albicans in dual-species interaction.IMPORTANCEThe anti-Candida albicans activity of Lactiplantibacillus plantarum has been explored in the past decades. However, the importance of C. albicans yeast form and the effect of C. albicans on L. plantarum had also been omitted. In this study, the dual-species interaction of L. plantarum and C. albicans was investigated with a focus on the transcriptomes. Cell-to-cell direct contact and co-aggregation with L. plantarum cells surrounding C. albicans yeast cells were observed. Upon polymicrobial transcriptomics analysis, interesting changes were identified, including contrary changes in two L. plantarum quorum-sensing systems and reduced cell survival-related pathways and pathogenesis determinants in C. albicans.

Characterization of a symbiotic beverage based on water-soluble soybean extract fermented by Lactiplantibacillus plantarum ATCC 8014.

The health benefits of functional foods are associated with consumer interest and have supported the growth of the market for these types of foods, with emphasis on the development of new formulations based on plant extracts. Therefore, the present study aimed to characterize a symbiotic preparation based on water-soluble soy extract, supplemented with inulin and xylitol and fermented by Lactiplantibacillus plantarum ATCC 8014. Regarding nutritional issues, the symbiotic formulation can be considered a source of fiber (2g/100mL) and proteins (2.6g/100mL), and it also has a low-fat content and low caloric value. This formulation, in terms of microbiological aspects, remained adequate to legal standards after storage for 60days under refrigeration and also presented an adequate quantity of the aforementioned probiotic strain, corresponding to 9.11 Log CFU.mL-1. These viable L. plantarum cells proved to be resistant to simulated human gastrointestinal tract conditions, reaching the intestine at high cell concentrations of 7.95 Log CFU.mL-1 after 60days of refrigeration. Regarding sensory evaluation, the formulation showed good acceptance, presenting an average overall impression score of 6.98, 5.98, and 5.16, for control samples stored for 30 and 60days under refrigeration, respectively. These results demonstrate that water-soluble soy extract is a suitable matrix for fermentation involving L. plantarum ATCC 8014, supporting and providing data on the first steps towards the development of a symbiotic functional food, targeting consumers who have restrictions regarding the consumption of products of animal origin, diabetics, and individuals under calorie restrictions.

Assessment of the Physicochemical, Antioxidant, Microbial, and Sensory Attributes of Yogurt-Style Products Enriched with Probiotic-Fermented Aronia melanocarpa Berry Juice.

The aim() of this study was to create() various formulations of yogurt enriched with freeze()-dried adjuncts, namely() (i) probiotic Lactobacillus plantarum ATCC 14917 culture(), and (ii) L. plantarum ATCC 14917 fermented black chokeberry juice, along with a commercial() starter culture(). The goal was to enhance() functionality and optimize the nutritional() value() of the products. These new yogurt-style() formulations were subsequently() compared with commercially produced yogurt. All products demonstrated() favorable() physicochemical properties, and the probiotic strain() consistently() maintained viable() levels exceeding 7 log() cfu/g throughout() the entire() storage() period(). The fermented milk produced with the adjunct-free L. plantarum cells, as well as the yogurt produced with the proposed() lactobacilli-fermented chokeberry juice, exhibited the highest lactic acid() production() (1.44 g/100 g yogurt by the end of storage()). Levels of syneresis were observed at lower() values() in yogurt produced with freeze()-dried fermented chokeberry juice. Yogurts prepared() with the lactobacilli-fermented freeze()-dried chokeberry juice displayed elevated total() phenolic content() and antioxidant capacity() (25.74 µg GAE/g and 69.05 µmol TE/100 g, respectively()). Furthermore, sensory tests revealed a distinctive() fruity flavor() in samples incorporating fermented juice. The results demonstrate() that probiotic L. plantarum-fermented chokeberry juice enhances() both the antioxidant capacity() and the viability of beneficial() bacteria() in yogurt while it can be readily() applied and commercialized, especially in the form of a freeze()-dried formulation.

A mutualistic symbiosis‐like system: double‐layer nanofiber film incorporated Lactiplantibacillus plantarum for Mongolian cheese preservation

SummaryHererin, the biopreservation (Lactiplantibacillus plantarum) was embedded into double‐layer nanofiber film (BDNF) composed of poly‐L‐lactic acid and polyethylene oxide via electrospinning process. Results showed that the embedded L. plantarum cells could manage to survive and maintain a high viability for about 15 days at 4 °C in the absence of external nutrients. The immobilisation of L. plantarum cells had no negative effect on their antibacterial activity. The application of BDNF on Mongolian cheese (MC) was constructed as a mutualistic symbiosis‐like system (MSS). Within BDNF‐MC‐MSS, nutritious matrix endowed L. plantarum a continuous antibacterial effect against undesirable microorganisms. Furthermore, the Mongolian cheese in MSS exhibited better quality because the packaging could strongly preserve them by inhibiting the growth of moulds and yeasts, reducing water loss, slowing fat precipitation, and improving texture characteristics during the storage period. The results suggested the feasibility of BDNF‐MC‐MSS as a novel way for Mongolian cheese preservation.

In Vitro Prebiotic Effects and Antibacterial Activity of Five Leguminous Honeys.

Honey is a natural remedy for various health conditions. It exhibits a prebiotic effect on the gut microbiome, including lactobacilli, essential for maintaining gut health and regulating the im-mune system. In addition, monofloral honey can show peculiar therapeutic properties. We in-vestigated some legumes honey's prebiotic properties and potential antimicrobial action against different pathogens. We assessed the prebiotic potentiality of honey by evaluating the antioxidant activity, the growth, and the in vitro adhesion of Lacticaseibacillus casei, Lactobacillus gasseri, Lacticaseibacillus paracasei subsp. paracasei, Lactiplantibacillus plantarum, and Lacticaseibacillus rhamnosus intact cells. We also tested the honey's capacity to inhibit or limit the biofilm produced by five pathogenic strains. Finally, we assessed the anti-biofilm activity of the growth medium of probiotics cultured with honey as an energy source. Most probiotics increased their growth or the in vitro adhesion ability to 84.13% and 48.67%, respectively. Overall, alfalfa honey best influenced the probiotic strains' growth and in vitro adhesion properties. Their radical-scavenging activity arrived at 83.7%. All types of honey increased the antioxidant activity of the probiotic cells, except for the less sensitive L. plantarum. Except for a few cases, we observed a bio-film-inhibitory action of all legumes' honey, with percentages up to 81.71%. Carob honey was the most effective in inhibiting the biofilm of Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus; it retained almost entirely the ability to act against the bio-film of E. coli, L. monocytogenes, and S. aureus also when added to the bacterial growth medium instead of glucose. On the other hand, alfalfa and astragalus honey exhibited greater efficacy in acting against the biofilm of Acinetobacter baumannii. Indigo honey, whose biofilm-inhibitory action was fragile per se, was very effective when we added it to the culture broth of L. casei, whose supernatant exhibited an anti-biofilm activity against all the pathogenic strains tested. Conclusions: the five kinds of honey in different ways can improve some prebiotic properties and have an inhibitory biofilm effect when consumed.

Construction of a Temperature-Sensitive Shuttle Vector between Lactic Acid Bacteria and Escherichia coli and Its Application to a Tn10-Based Random Mutagenesis Tool in Lactic Acid Bacteria.

In the present study, we have obtained a temperature-sensitive replication mutant in the Escherichia (E.) coli-lactic acid bacterium (LAB) shuttle vector pLES003-b carrying erythromycin-resistance gene by error-prone PCR technique. Among 858 clones obtained in the construction of the random mutation libraries of pLES003-b in the ori and repA regions, three clones could grow normally at 28 °C but not at 42 °C. One of the clones was designated as pLES003-b TS1. The sequencing analysis of pLES003-b TS1 revealed that the plasmid has four substitution mutations (376G > A, 435A > T, 914C > A, and 1996T > A) and one insertional mutation (1806_1807insA). Among those mutations, substitution mutation 914C > A, which leads to a CGC-to-AGC codon change at position 44 of the RepA protein (arginine-to-serine substitution mutation: R44S in RepA), was predicted to be a cause of temperature sensitivity. Therefore, the C-to-A substitution was introduced into the repA gene in pLES003-b using a site-directed mutagenesis method, and the resultant plasmid was electroporated into a Lactobacillus (L.) plantarum cell. The resultant transformant cannot grow at 42 °C in the presence of erythromycin, which is used as a selective marker, indicating that the R44S point mutation in the RepA protein may be crucial for temperature sensitivity. Furthermore, we have developed a new plasmid as an efficient genetic engineering tool for random insertional mutagenesis in LABs using a combination of transposon Tn10 and the temperature-sensitive replication system in pLES003-b. The resultant plasmid vector, which was designated pLES-Tn10-TS1, would be useful for genetic analysis of the functional molecule in lactic acid bacterial strains.

Improved infectious burn wound healing by applying lyophilized particles containing probiotics and prebiotics

Lactiplantibacillus plantarum cells were encapsulated in a mixture of cationic and anionic polymers, with the final composition stabilized through freeze-drying. A D-optimal design was used to examine the effects of different polymer concentrations as well as adding prebiotics on the probiotic viability and swelling behavior of the formulations. Scanning electron micrographs revealed stacked particles capable of rapidly absorbing significant amounts of water. These images corresponded to initial swelling percentages of around 2000% for the optimal formulation. The optimized formula had a viability percentage of more than 82%, with the stability studies suggesting that the powders should be stored at refrigerated temperatures. The physical characteristics of the optimized formula were examined to ensure compatibility with its application. According to antimicrobial evaluations, the difference in pathogen inhibition between formulated and fresh probiotics was less than a logarithm. The final formula was tested in vivo and showed improved wound healing indicators. The optimized formula resulted in a higher rate of wound closure and infection clearance. Furthermore, the molecular studies for oxidative stress indicated that the formula could modify wound inflammatory responses. In histological investigations, the probiotic-loaded particles functioned exactly as efficaciously as silver sulfadiazine ointment did.

Effects of additives containing a novel strain on the fermentation characteristics, structural carbohydrates, and α-tocopherol content of rice straw and corn stover silages

A novel α-tocopherol-producing bacteria strain was isolated and identified as Bacillus tequilensis QH1 (QH1). The effects of QH1 strain inoculation alone (QH), combined with cell wall degradation enzyme (QC), or Lactiplantibacillus plantarum subsp. plantarum YM3 and cell wall degradation enzyme (QLC) as the additives on the fermentation characteristics, structural carbohydrates, and α-tocopherol content of rice straw and corn stover silages were investigated, and without additives as the control (CON), in 4 replicates. After silages were kept in a laboratory cabinet (26–34 ℃) and the dark for 42 d, experimental silos (polyethylene plastic bags) were opened for analysis. The results exhibited that the control and additives-treated rice straw and corn stover were ensiled well, indicated by high lactic acid content and little butyric acid content. The QH and QC degraded structural carbohydrates, demonstrated by lower (P < 0.001) neutral detergent fiber (NDF) and acid detergent fiber (ADF) than the control, but did not enhance lactic acid fermentation, evidenced by lower (P < 0.001) lactic acid content in QH-treated silages compared with the control silages. The effect of QLC on degrading structural carbohydrates was influenced by material factors, evidenced by no role in decreasing the contents of NDF and ADF in rice straw silage and a good role in decreasing the contents of NDF and ADF in corn stover silage. However, the water-soluble carbohydrate (WSC) contents in both rice straw and corn stover silages were increased (P < 0.001) by QLC compared with the control. The control and additives-treated silages had much higher (P < 0.001) α-tocopherol content and lower (P < 0.001) chlorophyll content compared with the material before ensiling. Compared with the control, higher α-tocopherol content was found in QH-treated rice straw (P = 0.071) and corn stover silages (P < 0.05), and QLC-treated corn stover silage (P < 0.05). Therefore, the QH1 strain had the potential to be applied in rice straw silage production, and QLC was recommended to be applied in corn stover silage production.Graphical

Lactobacillus plantarum Metabolites Elicit Anticancer Effects by Inhibiting Autophagy-Related Responses.

Lactobacillus plantarum (L. plantarum) is a probiotic that has emerged as novel therapeutic agents for managing various diseases, such as cancer, atopic dermatitis, inflammatory bowel disease, and infections. In this study, we investigated the potential mechanisms underlying the anticancer effect of the metabolites of L. plantarum. We cultured L. plantarum cells to obtain their metabolites, created several dilutions, and used these solutions to treat human colonic Caco-2 cells. Our results showed a 10% dilution of L. plantarum metabolites decreased cell viability and reduced the expression of autophagy-related proteins. Moreover, we found co-treatment with L. plantarum metabolites and chloroquine, a known autophagy inhibitor, had a synergistic effect on cytotoxicity and downregulation of autophagy-related protein expression. In conclusion, we showed the metabolites from the probiotic, L. plantarum, work synergistically with chloroquine in killing Caco-2 cells and downregulating the expression of autophagy-related proteins, suggesting the involvement of autophagy, rather than apoptosis, in their cytotoxic effect. Hence, this study provides new insights into new therapeutic methods via inhibiting autophagy.

Optimization of co-encapsulation of L. plantarum cells and Silybum marianum seed extract and evaluation of protective effect of extract on cells survival in simulated gastrointestinal fluids

In the present study, Lactobacillus plantarum (MT, ZH593) native cells and Silybum marianum seed extract (SMSE; rich in antioxidant) were co-encapsulated in alginate microbeads by the internal gelatinization emulsion method. The effects of different concentrations of sodium alginate, SMSE and CaCl2 on microbead characteristics were optimized. Under optimum conditions small spherical microbeads (161.82 ± 13.4 μm) with the highest cell encapsulation efficiency (79.84 ± 4.07%) were produced and the highest antioxidant activity (51.92 ± 2.14%) was obtained. The results showed that the co-encapsulation of L. plantarum with SMSE significantly (P < 0.05) increased the viability of cells (approximately 0.71 log CFU/mL) and the release of the extract (approximately 9–10%) in gastric simulation and intestinal simulation fluids, respectively, when compared with microencapsulation without SMSE addition. Also, microbeads coating with whey protein isolate (WPI; 2.76%) resulted in the higher protection in simulated gastrointestinal fluids than coating with chitosan. The results of this study indicated that the WPI-coated alginate microbeads were a good carrier matrix for the controlled delivery of SMSE (as a new non-carbohydrate prebiotic compound) and increased the viability of L. plantarum in the lower part of the gastrointestinal tract.

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.

The Bacillary Postbiotics, Including 2-Undecanone, Suppress the Virulence of Pathogenic Microorganisms

Secreted molecules from probiotic Bacilli have often been considered potential pharmaceuticals to fight infections caused by bacterial or yeast pathogens. In the present study, we investigated the antagonistic potential of secreted probiotic filtrates (hereafter, postbiotics) derived from Lactobacillus plantarum cells against pathogenic microorganisms, such as Escherichia coli, Staphylococcus aureus, and Candida albicans. We found that the postbiotics mitigate the biofilms of the tested pathogens with no notable effect on their planktonic growth. In addition, the postbiotics suppressed some virulence traits, for instance, the dendrite swarming motility of E. coli and yeast-to-hyphal switch in C. albicans. Further assays with an active constituent produced by the L. plantarum cells–2-undecanone revealed two significant findings: (i) 2-undecanone inhibits C. albicans biofilms and hyphae in vitro and in a Caenorhabditis elegans model, and (ii) it interacts specifically with Gln 58 amino acid residue of hyphal wall protein-1 (Hwp-1) in molecular docking analysis. The results suggest the targeted mode of antagonistic action of 2-undecanone against C. albicans biofilm. In total, the findings of the study depict an appealing strategy to use postbiotics, including specific ketone molecules, produced by L. plantarum for developing novel antibiofilm and anti-hyphal pharmaceuticals.

Lactobacillus plantarum as Bio-Control Agent during Egg Incubation of African Catfish (Clarias gariepinus) – Effects on Microbial Loads and Water Quality Parameters

This study evaluated the heterotrophic bacteria and fungi loads and water quality parameters when Lactobacillus plantarum was employed as bio-control agent during egg incubation of Clarias gariepinus. The L. plantarum cells were inoculated into incubating water in 6-litre bowl at bacterial concentration of 2×103, 2×106 and 2×109 cfu L-1. Bowls with 1 ppt tetracycline solution and with no test bacteria / drug served as positive and negative controls respectively. 3 g of C. gariepinus fertilized eggs were incubated in these bowls under static water condition for 30 hours at room temperature, after which hatchability was determined. The water in each bowl was analyzed before, during and after egg incubation. The results indicated that all L. plantarum treatment groups recorded significantly (p&lt;0.05) reduced Enterobacteriaceae and fungi counts in the incubating water, with the optimum concentration recorded at 2×106 cfu L-1. There were significant reductions (p&lt;0.05) in the dissolved oxygen and pH of water at 30 hours of incubation when compared with the values obtained at 10 hour of incubation in all experimental groups. The fertilized eggs hatched in all treatment groups except those inoculated with 2×109 cfu L-1 L. plantarum, while hatchlings from positive control (tetracycline solution) groups were observed to be less viable than the probiotic-treatment and negative control (non-probiotic treatment) groups. It can be concluded from this study that addition of 2×106 cfu L-1 of L plantarum into incubating water reduced microbial loads, but did not improve water quality parameters (dissolved oxygen and pH) and hatchability of C. gariepinus eggs.

Sucrose, maltodextrin and inulin efficacy as cryoprotectant, preservative and prebiotic – towards a freeze dried Lactobacillus plantarum topical probiotic

Probiotic formulations must contain the right strain(s) in sufficient numbers when administered to confer the desired health benefit. However, significant cell death can occur during freeze-drying and over storage. This study assesses various saccharides for their ability to protect Lactobacillus plantarum cells over freeze-drying and storage, as well as their potential to act as prebiotics. The cryoprotective potential of 10% (m/v) of skimmed milk, inulin, maltodextrin, and sucrose were investigated during freeze-drying. Storage was assessed over 12 weeks at 4 °C and room temperature. Improved cell survival over freeze drying was observed with all the saccharides. However, only maltodextrin and sucrose retained cell viability over storage at 4 °C. Overall, skimmed milk demonstrated the highest survival up to 91%. Despite good cryoprotectant performance, inulin provided the least protection over storage, with <1% cell survival. Prebiotic potential was determined through growth experiments with 2% (m/v) of the saccharides in glucose-free MRS. All saccharides supported cell growth, with sucrose performing best and inulin worst.

General characteristics of the influence of surfactants on the bacteriolytic activity of lysozyme based on the example of enzymatic lysis of Lactobacillus plantarum cells in the presence of Tween 21 and SDS

The general characteristics of the effect of surfactants on the activity of lysozyme were demonstrated. The kinetics of bacterial cell lysis is consistent with the Michaelis-Menten equation and the presence of surfactants does not shift the pH-optimum of activity. Surfactants do not change the Km value but instead, affect the Vmax value. The experimental dependencies are well described by theoretical equations, which assume three surfactant binding sites on the lysozyme molecule. The dependencies of the activity of lysozyme on the surfactant concentration are either a step type (i.e., a higher plateau becomes a lower plateau), or a dependency with a maximum and continuation of the curve in the form of a plateau but with an increase in the surfactant concentration. It can be assumed that there is a mechanism for the regulation of lysozyme activity by an unknown natural factor that has a suitable hydrophobic radical capable of binding to the surface of lysozyme.

Shelf life of Microencapsulated and Free Cells of Lactobacillus plantarum IS-10506 at Different Temperatures

Survival of microencapsulated probiotic Lactobacillus plantarum IS-10506 ofdadih origin at different storage conditions has been investigated. L. plantarum cells suspension was dispersed in Flocel pH 101 mixed with skim milk powder and dried by Fluid Bed Dryer (FBD) at 37°C for 2 hours, then microencapsulated by 4.75% (w/v) sodium alginate and 5.5% (w/v) calcium chloride. The microencapsulated and free cells probiotics were packed in standing aluminium pouch and stored at three different temperatures, 24°C (room temperature), 4°C (chiller), and-20°C (freezer) for 24 weeks, and the viable counts of probiotic were enumerated using MRS Agar medium every two weeks. Microencapsulated and free cells of probiotic Lactobacillus plantarum IS-10506 showed stable viability at -20°C for 24 weeks. At 4°C free cells showed significant decreased of viability while microencapsulated cells showed stable viability at week 24. Storage at 24°C led to significant loss of viability (p< 0.05) of both free cells and microencapsulated cells after 8 and 10 weeks, respectively, to undetectable level. Moisture content in both of free cells and microencapsulated cells at 24° C significantly increased at week 2. While at 4°C, there was significant increase of moisture content observed in free cells at week 2, and microencapsulated cells showed significant increase of moisture content at week 10. Likewise, at -20°C, moisture content of both free and microencapsulated cells showed significant increase at week 2 and 10, respectively.

Comparison of Cytokine Expression in Human PBMCs Stimulated with Normal and Heat-Shocked Lactobacillus plantarum Cell Lysate.

Regulation of immune responses is among the beneficial effects of probiotic bacteria on human health. In this study, we aim to investigate the effect of normal and heat-shocked Lactobacillus plantarum PTCC 1058 cell lysate on cytokine expression by human PBMCs. The mid-exponential phase L. plantarum (108 CFU/mL) were used to prepare cell lysate. Isolated PBMCs were stimulated with 100 µg/mL of each normal and heat-shocked L. plantarum cell lysate for 72 h. Non-stimulated PBMCs were also evaluated as negative control. The mRNA expression of IL-6, IL-10, IFN-ɣ, TNF-α, and TGF-β genes was determined by quantitative RT-PCR amplification of total RNA extracted from PBMCs. Both types of cell lysate were able to increase pro-inflammatory cytokines and decrease anti-inflammatory cytokines. However, this effect was significantly stronger in heat-shocked cell lysate-treated PBMCs. Moreover, comparison of IFN-ɣ/IL-10, IFN-ɣ/TGF-β, IL-6/IL-10, IL-6/TGF-β, and TNF-α/IL-10 ratios in both conditions demonstrated that in the heat-shocked group, all of the above ratios were significantly higher than normal lysate treatment (p˂0.001), suggesting that heat-shocked probiotics are a potent inducer of the immune system in comparison to intact probiotics. Regarding these results, it may be possible to develop a new postbiotic product for the stimulation of immune responses of cancer patients or individuals who suffer from an immune defect.

THE VIABILITY OF ENCAPSULATED Lactobacillus plantarum DURING CUPCAKE BAKING PROCESS, STORAGE, AND SIMULATED GASTRIC DIGESTION

In this study, the Lactobacillus plantarum viability in the cupcake according to baking time was investigated for the first time. L. plantarum was microencapsulated by the emulsion method in κ-carrageenan mixed with skim milk (CS sample) or carrageenan coated by skim milk (CcS sample). The average size, and the L. plantarum viability during cupcake baking, cold storage and in the simulated intestinal fluid (SGF) were investigated. The result showed that the particle size was 165μm and 320μm for the CS and CcS samples respectively. In the cupcake baking process indicated that the L. plantarum viability in control samples was decreased 0.21; 0.66; 2.13; and 5.33 log CFU/cake after 2; 4; 8; and 12 min baking respectively as compared to the initial, whereas the decreasing of the L. plantarum viability was 0.22 to 0.34; 0.80 to 0.90; 1.48 to 1.50; and 3.58 to 3.80 log CFU/cake in CS samples and CcS samples respectively. The pH value of the control samples was 6.8 to 6.5 which tended to be lower than the microencapsulated samples during 14 days of storage, though there was not a significant difference. Additionally, the L. plantarum viability in the control, CS and CcS samples was tended to increase slightly during storage. However, L. plantarum cells showed high sensitivity with the SGF medium. The longer the storage time, the more sensitive L. plantarum in SGF. The CcS sample showed significant higher protective efficacy in SGF than the CS samples. The same result was not observed in simulated intestinal fluid. In the sensory test, the difference between the cupcake with and without the addition of microcapsules was not significant.

Novel peptides contribute to the antimicrobial activity of camel milk fermented with Lactobacillus plantarum IS10

Fermented camel milk is a good source of peptides including novel peptides produced by the starter culture. This study aimed to determine the novel peptides that contribute to the antimicrobial activity of fermented camel milk. Camel milk was pasteurized at 90 °C for 30 min and fermented with Lactobacillus plantarum IS10 for 24 h at 42 °C. The water-soluble extract was subjected to RP-HPLC fractionation and LC-MS/MS in combination with PEAKS STDIO software to identify the novel peptides via de novo sequencing. The antimicrobial activity was determined using a 96-well microtiter plate assay, showing a significant decline in pH from 6.6 at 0 h to 4.1 at 24 h with an increasing L. plantarum cell count from Log10 5.5 CFU mL−1 at 0 h to Log10 7.4 CFU mL−1 at 24 h. Twenty-one fractions were obtained by RP-HPLC, with fraction 14 demonstrating the highest antibacterial activity towards Escherichia coli and Staphylococcus aureus subsp. aureus. Fraction 14 contained 30 novel peptides with a molecular weight ranging from 598 to 2053 Da, with seven peptides showing more than 50% similarity to antimicrobial peptides contained in the database. The seven novel peptides inhibited the growth of E. coli and S. aureus subsp. aureus, contributing to the antimicrobial activity of fermented camel milk.