Plantarum Cells Research Articles

Analyses of the Effect of Peptidoglycan on Photocatalytic Bactericidal Activity Using Different Growth Phases Cells of Gram-Positive Bacterium and Spheroplast Cells of Gram-Negative Bacterium

We conducted photocatalytic experiments focusing on the peptidoglycan layer to elucidate the details of the mechanism of photocatalytic sterilization. The previous study of our laboratory suggested that the presence of the peptidoglycan layer increases the bactericidal effect. To further verify it, the following experiments were performed: experiments on cells with different peptidoglycan layer thickness used Lactobacillus plantarum cells with different growth phases, experiments on cells with the thin peptidoglycan layer used Escherichia coli cells and spheroplast cells from which the peptidoglycan layer was removed from E. coli cells. The bactericidal effects increased as the growth progresses of L. plantarum. It was confirmed by TEM that the thickness of the peptidoglycan layer increased with cell growth. The survival rates of E. coli intact cells were significantly lower than those of spheroplast cells. These results strongly suggest that the peptidoglycan layer enhances the photocatalytic bactericidal effect. As a result of allowing the photocatalytic reaction to act on peptidoglycan, the amount of hydroxyl radical was smaller, and the amount of hydrogen peroxide was higher than in the absence of peptidoglycan. It is suggested that peptidoglycan may convert produced hydroxyl radical to hydrogen peroxide.

Procena nutritivnog sastava i antifungalni potencijal bakteriocinogenih bakterija mlečne kiseline iz katija na toksigeni Aspergillus flavus

In this study, the nutrient contents of "Kati", a fermented cereal-based food, was revealed and antifungal activity of bacteriocin producing lactic acid bacteria (LAB) from "Kati" was assessed against aflatoxigenic Aspergillus flavus (A. flavus). The protein content (9.29%) of "Kati" was higher than (p < 0.05) wet milled-fermented sorghum (6.17%). During fermentation of milled sorghum to ready-to-eat 'Kati', anti-nutrient contents was reduced (p < 0.05) from 1.22 to 0.72 mg/100 g, 3.13 to 1.13 mg/100 g and 7.31 to 3.02 mg/100 g for tannin, phenol and phytates, respectively. Molecular technique revealed the identity of isolated LAB as Lactobacillus pentosus BS MP-10, L. paracasei 4G330, L. brevis ABRIINW, L. casei KG-5, L. sakei strain RFI LAB03, L. fermentum JCM 8607, L. plantarum KLDS 1.0607, L. rhamnosus JCM 8602 and L. lactis XLL1734. Among the isolated LAB, L. plantarum, L. lactis and L. fermentum have significant (p < 0.05) zones of inhibition of 11.0 mm, 9.1 mm and 7.8 mm, respectively, against aflatoxigenic A. flavus. The pronounced antifungal potency of L. plantarum cell free supernatant could be attributed to the presence of 3-phenyllactic acid, benzeneacetic acid, plantaricin (bacteriocin) as revealed by gas chromatography/mass Spectrometry (GC-MS). LAB produced metabolites with antifungal property that contributed to shelf life, flavor and nutrient contents of fermented foods.

Knock out of sHSP genes determines some modifications in the probiotic attitude of Lactiplantibacillus plantarum

ObjectiveWe investigated whether the knock out of small heat shock protein (sHSP) genes (hsp1, hsp2 and hsp3) impact on probiotic features of Lactiplantibacillus plantarum WCFS1, aiming to find specific microbial effectors involved in microbe-host interplay.ResultsThe probiotic properties of L. plantarum WCFS1 wild type, hsp1, hsp2 and hsp3 mutant clones were evaluated and compared through in vitro trials. Oro-gastro-intestinal assays pointed to significantly lower survival for hsp1 and hsp2 mutants under stomach-like conditions, and for hsp3 mutant under intestinal stress. Adhesion to human enterocyte-like cells was similar for all clones, though the hsp2 mutant exhibited higher adhesiveness. L. plantarum cells attenuated the transcriptional induction of pro-inflammatory cytokines on lipopolysaccharide-treated human macrophages, with some exception for the hsp1 mutant. Intriguingly, this clone also induced a higher IL10/IL12 ratio, which is assumed to indicate the anti-inflammatory potential of probiotics.ConclusionssHSP genes deletion determined some differences in gut stress resistance, cellular adhesion and immuno-modulation, also implying effects on in vivo interaction with the host. HSP1 might contribute to immunomodulatory mechanisms, though additional experiments are necessary to test this feature.

Analytical combinations to evaluate the macromolecular composition of extracellular substances (ECS) from Lactobacillus plantarum cell culture media.

Sugar-enriched media are used to produce extracellular substances (ECS) by Lactobacillus plantarum WCSF1, with a focus on growing stages and carbon source substrates. Combination of size exclusion chromatography and ATR-FTIR spectroscopy provides physicochemical patterns of bulk ECS produced along culture growing time. Secreted biopolymers present polydisperse and high molecular weight distributions, with significant amounts of carbohydrates and proteins. Results, supported by a multivariate statistical analysis, enable to differentiate the macromolecular content of bacterial ECS along the growing stages regardless of the growing media, highlighting a higher production of proteinaceous materials compared to polysaccharides. At the end of the exponential phase, common exoproteins were present in all the tested sugar-enriched media such as transglycosylases between 20 and 35kDa, a muropeptidase at 36.9kDa and a cell wall hydrolase. Additionally, L. plantarum WCFS1 secretes ECS with a greater diversity of proteins, when growing in the sucrose-enriched media. Graphical abstract.

Discovery of novel Lactobacillus plantarum co-existence-associated influencing factor(s) on Saccharomyces cerevisiae fermentation performance

The food fermentation performed by Saccharomyces cerevisiae sometimes needs the co-existence of or is occasionally contaminated by other microorganisms. Among these microorganisms, the co-existed lactic acid bacteria (LAB) could inhibit S. cerevisiae growth through secreting organic acids and competing for viable space and nutrients. However, besides these three known major inhibition factors, are there any other unknown influence(s) of LAB on S. cerevisiae? In this study, a “reeling-off”-based design was performed to discover the potential novel LAB co-existence-associated inhibition factor(s) on S. cerevisiae fermentation performance illustrated by the case of Lactobacillus plantarum. After excluding the previously reported major influence factors one by one, L. plantarum ATCC8014 could still inhibit yeast biomass. Such results suggested that there might really exist such previously un-detected factor(s) functioning in inhibiting yeast cell growth. Furthermore, it was discovered that the L. plantarum cell wall could inhibit S. cerevisiae growth through direct contact. Interestingly, such direct contact could also improve ethanol tolerance of S. cerevisiae and ethanol production efficiency per OD. These results would strengthen our understanding of microbial interactions during food fermentation.

Effect of hydrogen peroxide on the dehydrogenase and quinone-reductase activity of irradiated Lactobacillus plantarum cells

The resistance of lactobacilli to oxidative stress is of great importance for their applicability as probiotics. This study aimed to evaluate the response of Lactobacillus plantarum strain ATCC® 14917™, grown in either de Man, Rogosa, and Sharpe agar (MRS medium) or tryptic soy broth (TSB medium), to 1–2 mM H2O2 after the exposure to different doses of ionising radiation. Two bacterial extracellular enzyme groups, dehydrogenases (DHAs) and quinone reductases (QRs), served as the criteria of viability and antioxidant activity, respectively. The irradiated L. plantarum culture grown in TSB showed increased QR activity at irradiation doses of 2–50 Gy, with the maximum activity at 10 Gy, compared to non-irradiated cells. The QR activity of the MRS-grown culture was increased significantly (p < 0.05) in the presence of H2O2 for the cells subjected to irradiation, compared to the control. The cultivation of L. plantarum in TSB resulted in considerable morphological changes in the 24 h culture. Our results indicate that the cultivation of L. plantarum in TSB activated the antioxidative potential of these bacteria. The most important aspect of this phenomenon is the extracellular enzyme activity that may directly influence the host organism by providing antioxidant activity.

In Ukrainian

The results are presented of a study on spectral characteristics, electron microscopy data and antibacterial properties of Lactobacillus plantarum cell matrices filled with biologically synthesized in the presence of surfactants (S) silver nanoparticles (bioAgNP). The dependences of spectral characteristic of cell suspension of lactic acid bacteria L.plantarum with synthesized bioAgNP on S concentration were analyzed, namely: cationic two quaternary ammonium salt (CS) aethonium and anionic sodium decyl phosphate (AS). To control the process of bioAgNP production in microorganism cells, the method of spectroscopy in ultraviolet and visible regions was used. The antibacterial properties of modified L. plantarum cells dependent on synthesis condition and their composition were testified by disco diffusion method. The results are presented of electron-microscopy investigation of treated with concentrated sulfuric acid bionanocomposite material. It is shown that addition at the synthesis of an ionogenic S to the precursor solution affects structural and size descriptions of biogenic silver formed in L. plantarum cells. Since a concentration more then the critical concentration of micelle formation, aethonium presence resulted in forming of two NPs fractions, namely: stabilized in a cell wall subcolloidal particles having absorption band at 380 nm and also aggregated particles having spectral shoulder at 440 nm. S addition promoted the red shift of absorption spectra dependent on CS concentration and medium pH, however not dependent on AS concentration. It is shown that antibacterial properties of modified with S nanobiocomposite materials mainly depend on the NPs content in lactic acid matrices and on their size. Joint application of bionanocomposite and aethonium preparation close to the critical micelle concentration allowed to rise their activity in relation to Gram(+)bacteria and, at the same time, to bring down on an order (from 1.0 to 0.1 %) the ordinary therapeutic dose of aethonium.

Effect of Isothiocyanates on the Activity of &lt;i&gt;Lactobacillus plantarum&lt;/i&gt; Exposed to Irradiation

Two isothiocyanates, i.e., sulforaphane (SFA) and sulforaphene (SFE), are suggested to be used as an alternative chemopreventive diet. This study was focused on the effect of SFA and SFE on Lactobacillus plantarum, which has been subjected to the irradiation (2-50 Gy). The cultures grown in De Man, Rogosa and Sharpe (MRS) and Tryptone Soya Broth (TSB) were compared in terms of bacteria physiological activity under tested conditions. Broth composition notably influenced the bacteria growth kinetic parameters, as well as culture response to the oxidative stress. Activity of L. plantarum cells after irradiation was evaluated by their dehydrogenase (DHA) and quinone-reductase (QR) activities. The enzyme activity was quantified in living cells. Bacterial cultures obtained in MRS and TSB broth, demonstrated contrasting characteristics in their enzyme activities. The MRS-grown culture did not show any QR activity, whereas the TSB-grown cells showed a non-linear response towards gamma-irradiation with a maximum inhibition being at 10 Gy. Addition of SFA or SFE in concentration of 1 µg/mL to the cultures before irradiation exposure recovered the QR activity from 23% in a non-amended variant up to 102% and 121%, respectively, taking the non-irradiated non-amended variant as 100%.

Cell Wall Anchoring of a Bacterial Chitosanase in Lactobacillus plantarum Using a Food-Grade Expression System and Two Versions of an LP TG Anchor.

Lactic acid bacteria (LAB) have attracted increasing interest recently as cell factories for the production of proteins as well as a carrier of proteins that are of interest for food and therapeutic applications. In this present study, we exploit a lactobacillal food-grade expression system derived from the pSIP expression vectors using the alr (alanine racemase) gene as the selection marker for the expression and cell-surface display of a chitosanase in Lactobacillus plantarum using two truncated forms of a LP × TG anchor. CsnA, a chitosanase from Bacillus subtilis 168 (ATCC23857), was fused to two different truncated forms (short-S and long-L anchors) of an LP × TG anchor derived from Lp_1229, a key-protein for mannose-specific adhesion in L. plantarum WCFS1. The expression and cell-surface display efficiency driven by the food-grade alr-based system were compared with those obtained from the erm-based pSIP system in terms of enzyme activities and their localisation on L. plantarum cells. The localization of the protein on the bacterial cell surface was confirmed by flow cytometry and immunofluorescence microscopy. The highest enzymatic activity of CsnA-displaying cells was obtained from the strain carrying the alr-based expression plasmid with short cell wall anchor S. However, the attachment of chitosanase on L. plantarum cells via the long anchor L was shown to be more stable compared with the short anchor after several repeated reaction cycles. CsnA displayed on L. plantarum cells is catalytically active and can convert chitosan into chito-oligosaccharides, of which chitobiose and chitotriose are the main products.

Development of chitosan-coated agar-gelatin particles for probiotic delivery and targeted release in the gastrointestinal tract

This study reports the development of a novel and simple formulation for probiotic delivery using chitosan-coated agar-gelatin gel particles. This methodology involves the production of agar-gelatin particles by thermally treating a mixture of agar and gelatin solutions at high temperatures (121 °C) and subsequently coating with chitosan. The particles were able to protect the probiotic strain Lactobacillus plantarum NCIMB 8826 during incubation for 2 h in simulated gastric fluid (pH 2), as no statistically significant loss (P > 0.05) in cell concentration was observed, and also resist dissolution in simulated intestinal fluid (pH 7.2). Interestingly, this protection is related to the fact that the intense thermal treatment affected the physicochemical properties of agars and resulted in the formation of a strong and tight polymer network, as indicated by the X-ray diffraction (XRD) analysis. Using an in vitro faecal batch fermentation model simulating the conditions of the distal part of the large intestine (pH 6.7–6.9), it was demonstrated by quantitative real-time PCR that the majority of L. plantarum cells were released from the agar-gelatin particles within 30 to 48 h. Overall, this work led to the development of a novel methodology for the production of probiotic-containing particles, which is simpler compared with current encapsulation technologies and has a lot of potential to be used for the controlled release of probiotics and potentially other solid bioactives in the large intestine.Key Points• Chitosan gel particles is a simple and scalable method of probiotic encapsulation.• Autoclaving agar-gelatin particles increases their stability at low pH.• Chitosan gel particles protected L. plantarum during gastrointestinal conditions.• Probiotics could be controlled release in the colon using chitosan gel particles.

Probiotic potential of lyophilized Lactobacillus plantarum GP

PurposeFreeze drying of Lactobacillus plantarum GP in the presence of wall materials to achieve improved survival and retention of probiotic functionality during storage.MethodsL. plantarum cells were lyophilized in the presence of inulin, fructooligosaccharides, lactulose, and/or skim milk. The lyophilized vials were stored at 8–10 °C up to 6 months and cells from these vials were evaluated for their probiotic functionality.ResultsL. plantarum GP freeze dried in the presence of wall material lactulose displayed viability of 98 ± 2.8% promising survival rate in the stress conditions of human digestive tract. The freeze dried cells of Lactobacilli retained the ability to adhere intestinal mucin layer, form biofilm, inhibit food spoilage and enteropathogens, produce β-galactosidase, bile salt hydrolase and γ-amino butyric acid, remove cholesterol, and scavenge DPPH radical.ConclusionLyophilized cells of L. plantarum GP retained all the functional characteristics without any significant loss during storage, which prompts to incorporate prebiotics for the development of stable functional food products.

Effect of calcium-alginate bead and Anoectochilus formosanus Hayata extract fluid on the viability of Lactobacillus plantarum ATCC 8014 and bioactive compounds in fermented apple juice

The aim of this study was to determinate the effect of the encapsulation by calciumalginate containing (MA sample) or non-containing Anoectochilus formosanus Hayata extracted fluid (M sample) on the survival of Lactobacillus plantarum ATCC 8014 in fermented apple juice for 60 hours. The antioxidant activity, total polyphenol, polysaccharide, pH values, and the density of L. plantarum were determined every 12 hours of fermentation. The fermented apple juice was stored at 4°C in 5 weeks. The pH value and the viable L. plantarum were evaluated during storage and in the simulation gastric medium after 4 weeks of storage. The results showed that bioactive compounds increased in the first 24 hours but decreased slowly in subsequent hours of fermentation in which the sample containing encapsulated bead had better results than free cells (F samples). The scavenging activity DPPH, total polyphenol, and polysaccharide of the MA sample were 6.58 mg Vit C/100mL; 304.65 mg GAE/100mL; and 2.98 mg Glu/100 mL, respectively. The viability of L. plantarum was maintained over 6 log CFU/mL for the encapsulated samples compared to 4 log CFU/mL for the F samples. The viability of encapsulated L. plantarum in A and MA samples was no significant difference during storage, but the survival rate of L. plantarum in MA sample was significantly higher than M samples in the SGF (Simulated gastric fluid) medium. The results indicated that adding the A. formosanus Hayata extract fluid into the calcium-alginate matrix protected L. plantarum cells during fermentation, storage and in the SGF medium.

Construction of a Lactobacillus plantarum Strain Expressing the Capsid Protein of Porcine Circovirus Type 2d (PCV2d) as an Oral Vaccine.

Porcine circovirus type 2 (PCV2) is a pathogenic virus that causes high rates of porcine death, resulting in severe economic losses to the swine industry. In recent years, the prevalence of PCV2d genotype infection in pigs has increased, but most commercially available vaccines were developed against the PCV2a strain and do not ensure complete protection from PCV2d. Here, we first constructed an expression vector for the antigenic ORF2-encoded capsid protein of PCV2d (pLp3050-His6-tag-capsid). We then utilized Lactobacillus plantarum to express the protein at mucosal sites in orally vaccinated mice. After transducing L. plantarum with pLp3050-His6-tag-capsid, the expressed protein could be found in cell wall and cell-free supernatant fractions by Western blotting. Using flow cytometry, we found that L. plantarum cells with surface-displayed capsid protein increased with time after SppIP induction. Finally, mice that were orally immunized 18 times with capsid-expressing L. plantarum showed increased levels of capsid-specific sIgA and virus neutralizing activity at mucosal sites, suggesting mucosal immunity had been stimulated by the vaccine. Overall, our findings demonstrate the feasibility and utility of a PCV2d-based vaccine, which may be of great value in porcine agriculture.

Encapsulation of Lactobacillus plantarum in cellulose based microgel with controlled release behavior and increased long-term storage stability

Probiotics are believed to provide benefits to human health; however, a good storage stability is the prerequisite for the probiotic products making function. Herein, we reported a pathway to fabricate the Ca-alginate/cryoprotectants/cellulose composite (ACFP) capsules to protect L. plantarum cells, which showed the minimal loss of viability during the vacuum freeze-drying process. The trehalose and whey protein isolate (WPI) ingredients in the cryoprotectants prolonged the dissolution time of Ca-alginate shell, which contributed to controlling the release of cells in the desired region. The dry ACFP capsules exhibited gradual release of L. plantarum cells in simulated intestinal fluid (SIF), 2.6 × 106 cfu/mL at 210 min. In addition, 0.1 g of the dry ACFP capsules showed the viable release amount of 3.3 × 106 cfu/mL after the storage of 160 days at 4 °C. The promising results provided a strategy of encapsulating probiotic cells to achieve long-term storage stability and enhanced controlled release behavior in simulated intestinal fluid in the meantime.

Inhibitory effect of Lactobacillus plantarum metabolites against biofilm formation by Bacillus licheniformis isolated from milk powder products

Process biofilms of Bacillus licheniformis present worldwide problem to the dairy industry because of their relevance to food spoilage and quality issues. In this study, metabolites of Lactobacillus plantarum were found to effectively inhibit biofilms formed by B. licheniformis. The biofilm formation was delayed by 10 h by the addition of L. plantarum cell free supernatant and controlling pH of the medium. Confocal laser scanning microscope images showed that L. plantarum metabolites decreased the number of B. licheniformis cells adhered to stainless steel and glass surfaces. Gel filtration chromatography results showed that B. licheniformis utilized the peptides in the growth medium (tryptic soy broth) with the molecular weights ranging from 613 to 1486 Da, and produced plentiful small peptides with the molecular weights ranging from 181 to 613 Da. Moreover, 3–10 kDa components of L. plantarum ultra-filtrates were proved to significantly inhibit biofilm formation by B. licheniformis. Thus, the metabolites produced by L. plantarum provide a novel approach for the prevention of B. licheniformis biofilms in the dairy industry.

Radiation processing of locust bean gum and assessing its functionality for applications in probiotic and enteral foods

The physicochemical and functional characteristics of irradiated locust bean gum (LBG) were investigated for their use as a source of dietary fibre in enteral food. Radiation processing mainly affected the molecular weight of the polymer in dose-dependent manner. The attributes like lowering of viscosity, increase in solubility and swelling index were better achieved with the use of irradiated polymer. A 17% reduction in glucose dialysis retardation index (GDRI) and decrease in bile acid dialysis retardation index (BDRI) due to irradiation were in agreement with the rate of depolymerization. LBG was also shown to protect probiotic L. plantarum cells during their passage in gastrointestinal conditions. Radiation processing of the gum further improved this property exhibiting only 3 log cycle decrease in count as compared to unirradiated polymer, exhibiting nearly 4 log cycle decrease from initial cell count of 9 log CFU mL−1. In view of the changes in the rheological properties of LBG due to irradiation, an enteral feed supplemented with irradiated LBG as source of dietary fiber was prepared without affecting the product viscosity.

Recovery of recombinant Mycobacterium tuberculosis antigens fused with cell wall-anchoring motif (LysM) from inclusion bodies using non-denaturing reagent (N-laurylsarcosine)

BackgroundThe current limitations of conventional BCG vaccines highlights the importance in developing novel and effective vaccines against tuberculosis (TB). The utilization of probiotics such as Lactobacillus plantarum for the delivery of TB antigens through in-trans surface display provides an effective and safe vaccine approach against TB. Such non-recombinant probiotic surface display strategy involves the fusion of candidate proteins with cell wall binding domain such as LysM, which enables the fusion protein to anchor the L. plantarum cell wall externally, without the need for vector genetic modification. This approach requires sufficient production of these recombinant fusion proteins in cell factory such as Escherichia coli which has been shown to be effective in heterologous protein production for decades. However, overexpression in E. coli expression system resulted in limited amount of soluble heterologous TB-LysM fusion protein, since most of it are accumulated as insoluble aggregates in inclusion bodies (IBs). Conventional methods of denaturation and renaturation for solubilizing IBs are costly, time-consuming and tedious. Thus, in this study, an alternative method for TB antigen-LysM protein solubilization from IBs based on the use of non-denaturating reagent N-lauroylsarcosine (NLS) was investigated.ResultsExpression of TB antigen-LysM fusion genes was conducted in Escherichia coli, but this resulted in IBs deposition in contrast to the expression of TB antigens only. This suggested that LysM fusion significantly altered solubility of the TB antigens produced in E. coli. The non-denaturing NLS technique was used and optimized to successfully solubilize and purify ~ 55% of the recombinant cell wall-anchoring TB antigen from the IBs. Functionality of the recovered protein was analyzed via immunofluorescence microscopy and whole cell ELISA which showed successful and stable cell wall binding to L. plantarum (up to 5 days).ConclusionThe presented NLS purification strategy enables an efficient and rapid method for obtaining higher yields of soluble cell wall-anchoring Mycobacterium tuberculosis antigens-LysM fusion proteins from IBs in E. coli.

Constitutive expression and cell-surface display of a bacterial \u03b2-mannanase in Lactobacillus plantarum

BackgroundLactic acid bacteria (LAB) are important microorganisms in the food and beverage industry. Due to their food-grade status and probiotic characteristics, several LAB are considered as safe and effective cell-factories for food-application purposes. In this present study, we aimed at constitutive expression of a mannanase from Bacillus licheniformis DSM13, which was subsequently displayed on the cell surface of Lactobacillus plantarum WCFS1, for use as whole-cell biocatalyst in oligosaccharide production.ResultsTwo strong constitutive promoters, Pgm and SlpA, from L. acidophilus NCFM and L. acidophilus ATCC4356, respectively, were used to replace the inducible promoter in the lactobacillal pSIP expression system for the construction of constitutive pSIP vectors. The mannanase-encoding gene (manB) was fused to the N-terminal lipoprotein anchor (Lp_1261) from L. plantarum and the resulting fusion protein was cloned into constitutive pSIP vectors and expressed in L. plantarum WCFS1. The localization of the protein on the bacterial cell surface was confirmed by flow cytometry and immunofluorescence microscopy. The mannanase activity and the reusability of the constructed L. plantarum displaying cells were evaluated. The highest mannanase activities on the surface of L. plantarum cells obtained under the control of the Pgm and SlpA promoters were 1200 and 3500 U/g dry cell weight, respectively, which were 2.6- and 7.8-fold higher compared to the activity obtained from inducible pSIP anchoring vectors. Surface-displayed mannanase was shown to be able to degrade galactomannan into manno-oligosaccharides (MOS).ConclusionThis work demonstrated successful displaying of ManB on the cell surface of L. plantarum WCFS1 using constitutive promoter-based anchoring vectors for use in the production of manno-oligosaccharides, which are potentially prebiotic compounds with health-promoting effects. Our approach, where the enzyme of interest is displayed on the cell surface of a food-grade organism with the use of strong constitutive promoters, which continuously drive synthesis of the recombinant protein without the need to add an inducer or change the growth conditions of the host strain, should result in the availability of safe, stable food-grade biocatalysts.

Use of gelatin and gum arabic for microencapsulation of probiotic cells from Lactobacillus plantarum by a dual process combining double emulsification followed by complex coacervation.

The objectives of this study were i) to microencapsulate probiotic cells of Lactobacillus plantarum through a dual process consisting of emulsification followed by complex coacervation using gelatin and gum arabic, ii) to characterize the lyophilized microcapsules, iii) to evaluate their behavior in simulated in vitro gastrointestinal conditions and iv) to evaluate the survival of microencapsulated probiotic cells during 45 days of storage at 8 °C, 25 °C and -18 °C. The optimized conditions for complex coacervation consisted of a 50:50 biopolymer ratio and pH = 4.0. Emulsification was followed by complex coacervation using gelatin and gum arabic. The microcapsules presented dispersibility of 0.183 ± 0.17 g·mL-1, moisture content of 4.5%, water activity of 0.34 ± 0.03 and hygroscopicity of 9.20 ± 0.43 g of absorbed water per 100 g. Their size ranged from 66.07 ± 3.04 μm to 105.66 ± 3.24 μm. Viability of the encapsulated L. plantarum cells was 8.6 log CFU·g-1 and the encapsulation efficiency was 97.78%. After in vitro simulation of gastrointestinal conditions, viability of the encapsulated cells was 80.4% whereas it was only 25.0% for the free cells at 37 °C. Probiotic cell viability was maintained during storage at 8 °C and - 18 °C for 45 days.

Intestinal adsorption of glucose, cholesterol and bile salt by simultaneous incorporation of edible microbiosorbent and intestinal bacteria

Abstract Natural edible adsorbents can play an important role in human healthcare via lowering the harmful materials from gut and regulating the microflora composition. In this work, several microalgae and plant sources, including Chlorella vulgaris (Ch), zucchini (Zu), ginger (Gi), rice bran (RB) and Zahedi date (ZD), were studied on the production of edible and bacterial biosorbents for the adsorption of glucose, cholesterol and bile salt in vitro. By screening the sources, Ch, Zu and Gi were selected for maximizing the production of Lactobacillus plantarum. Afterward, the optimized mixture of zucchini-ginger-C. vulgaris (ZuGiCh), obtained from the combination of the microparticles of zucchini (48.80 g/l), ginger (35.00 g/l) and C. vulgaris (39.30 g/l), maximized L. plantarum cells to 2.37 ± 1.86 × 109 CFU/ml and minimized Escherichia coli and Staphylococcus aureus cells to 4.53 ± 0.41 × 108 and 8.10 ± 0.61 × 108 CFU/ml, respectively. The simultaneous incorporation of S. aureus and ZuGiCh as an edible microbiosorbent resulted in the highest adsorption of glucose (57.65%) and cholesterol (83.65%) at initial concentration of 40 g/l adsorbate while the incorporation of L. plantarum and ZuGiCh showed the highest adsorption of bile salt (42.59%) at initial concentration of 80 g/l bile salt. The ZuGiCh microparticles can be used as a potentially intestinal adsorbent for improving microflora and lowering of health hazards from gut.