Development of a novel probiotic delivery system based on microencapsulation with protectants

Delivery of Probiotic-Loaded Microcapsules in the Gastrointestinal Tract: A Review

Probiotics are live microorganisms that inhabit the gastrointestinal tract and confer health benefits to consumers. However, a sufficient number of viable probiotic cells must be delivered to the specific site of interest in the gastrointestinal tract to exert these benefits. Enhanced viability and tolerance to sublethal gastrointestinal stress can be achieved using appropriate coating materials and food matrices for orally consumed probiotics. The release mechanism and interaction of probiotic microcapsules with the gastrointestinal tract have been minimally explored in the literature to date. To the authors' knowledge, no review has been published to discuss the nature of release and the challenges in the targeted delivery of probiotics. This review addresses gastrointestinal-related complications in the formulation of targeted delivery and controlled release of probiotic strains. It investigates the impacts of environmental stresses during the transition stage and delivery to the target region in the gastrointestinal tract. The influence of factors such as pH levels, enzymatic degradation, and redox conditions on the release mechanisms of probiotics is presented. Finally, the available methods to evaluate the efficiency of a probiotic delivery system, including in vitro and in vivo, are reviewed and assessed. The paper concludes with a discussion highlighting the emerging technologies in the field and emphasising key areas in need of future study.

An in vitro gastrointestinal model to evaluate the tolerance of encapsulated Lactobacillus and Lactococcus strains with synbiotic containing lactobionic acid via lyophilization technique to harsh gastric conditions during storage time

Probiotics are living microorganisms that have potential health benefits for the host when administered in the correct proportions. However, for these beneficial effects to be produced, viable probiotic cells need to reach the human intestine. This study used a gastrointestinal model to represent the pH variation and gastric enzymes that are involved in the digestion process. Eight Lactobacillus strains and one Lactococcus strain were encapsulated using sodium alginate. The aim of this study was to compare free probiotic bacteria with encapsulated probiotic bacteria and determine the number of viable probiotic cells that might reach the human intestine. Microencapsulation of probiotic organisms followed the extrusion method with an alginate compound. Microencapsulated and free probiotic bacteria were inoculated into 200 ml of MRS (Man, Rogosa, Sharpe) broth. Simulated gastric juice and bile and pancreatic salt were used to test the tolerance of free Lactobacillus and Lactococcus species and microencapsulated bacteria to acid pH and enzymes. To enumerate the microencapsulated probiotic organisms, the bacteria were released from the capsules after total digestion with sodium citrate solution. The number of live bacteria (as CFU/g) was determined using the plate count method on MRS plates incubated at 37 °C for 48 h. Bacterial cell viability was determined on MRS agar duplicate plates at different dilutions. The results indicated that microencapsulation of probiotic bacteria showed improved viability over free cells when given 2 h of exposure to acidic conditions, and also for 2 h of exposure to bile and pancreatic salt. Encapsulation with alginate can protect probiotic bacteria from acidic conditions and bile salts. This study attempted also to produce synbiotic preparations with lactobionic acid using nontoxic encapsulating substances. The microorganisms used were stabilized with protective substances, and their stability during storage was checked under room temperature conditions. The final modification of the method, involving placing the capsules in a solution of skimmed milk with 5 % sucrose and 0.35 % ascorbic acid, resulted in an increase in the survival rate of some strains of microorganisms during microencapsulation and lyophilization and demonstrated stability during storage at room temperature.

Utilizing chitosan and pullulan for the encapsulation of Lactiplantibacillus plantarum ZJ316 to enhance its vitality in the gastrointestinal tract

Lactiplantibacillus plantarum ZJ316 has demonstrated effective alleviation of gastritis and colitis, making it crucial to improve its viability within the gastrointestinal tract. In this study, Chitosan (CS) and pullulan (PUL) encapsulated nanofibers of ZJ316 were prepared using electrospinning, considering both the synergistic effects of prebiotics and probiotics and their protective effects. We found that increasing the CS ratio resulted in elevated conductivity of the polymer solution, while decreasing viscosity and pH. Scanning electron microscopy showed that at a CS: PUL ratio of 1:135, polymer filaments were difficult to form, and nanofiber diameter decreased with higher CS content. X-ray diffraction analysis confirmed the miscibility of CS and PUL, while ATR-FTIR demonstrated the presence of hydrogen bonding interactions between the two materials. Thermal analysis indicated that an increased CS concentration improved the thermal stability of the nanofibers. Based on these findings, the optimal CS:PUL ratio for electrospinning was determined to be 1:60. Encapsulation of ZJ316 in the nanofibers significantly enhanced its survival rate in simulated gastrointestinal fluid compared to free bacteria, with survival rates of 87.24 % (gastric) and 79.71 % (intestinal), respectively. This study provides valuable insights for the development of probiotic functional foods.

Co-encapsulation of probiotics with acylglycerols in gelatin-gum arabic complex coacervates: Stability evaluation under adverse conditions

Co-encapsulation of acylglycerols and probiotics may improve the resistance of probiotics to adverse conditions. In this study, three probiotic microcapsule models were constructed using gelatin (GE)-gum arabic (GA) complex coacervate as wall material: microcapsules containing only probiotics (GE-GA), microcapsules containing triacylglycerol (TAG) oil and probiotics (GE-T-GA) and microcapsules containing diacylglycerol (DAG) oil and probiotics (GE-D-GA). The protective effects of three microcapsules on probiotic cells under environmental stresses (freeze-drying, heat treatment, simulated digestive fluid and storage) were evaluated. The results of cell membrane fatty acid composition and Fourier transform infrared (FTIR) spectroscopy revealed that GE-D-GA could improve the fluidity of cell membrane, maintain the stability of protein and nucleic acid structure, and decrease the damage of cell membrane. These characteristics supported the high freeze-dried survival rate (96.24 %) of GE-D-GA. Furthermore, regardless of thermotolerance or storage, GE-D-GA showed the best cell viability retention. More importantly, GE-D-GA provided the best protection for probiotics under simulated gastrointestinal conditions, as the presence of DAG reduced cell damage during freeze-drying and the degree of contact between probiotics and digestive fluids. Therefore, co-microencapsulation of DAG oil and probiotics is a promising strategy to resist adverse conditions.

Soy lecithin increases the stability and lipolysis of encapsulated algal oil and probiotics complex coacervates

BACKGROUND

Co-encapsulation of probiotics and omega-3 oil using complex coacervation is an effective method for enhancing the tolerance of probiotics under adverse conditions, whereas complex coacervation of omega-3 oil was found to have low lipid digestibility. In the present study, gelatin (GE, 30 g kg^-1 ) and gum arabic (GA, 30 g kg^-1 ) were used to encapsulate Lactobacillus plantarum WCFS1 and algal oil by complex coacervation to produce microcapsules containing probiotics (GE-P-GA) and co-microcapsules containing probiotics and algal oil (GE-P-O-GA), and soy lecithin (SL) was added to probiotics-algal oil complex coacervates [GE-P-O(SL)-GA] to enhance its stability and lipolysis. Then, we evaluated the viability of different microencapsulated probiotics exposed to freeze-drying and long-term storage, as well as the survival rate and release performance of encapsulated probiotics and algal oil during in vitro digestion.

RESULTS

GE-P-O(SL)-GA had a smaller particle size (51.20 μm), as well as higher freeze-drying survival (90.06%) of probiotics and encapsulation efficiency of algal oil (75.74%). Moreover, GE-P-O(SL)-GA showed a higher algal oil release rate (79.54%), lipolysis degree (74.63%) and docosahexaenoic acid lipolysis efficiency (64.8%) in the in vitro digestion model. The viability of microencapsulated probiotics after simulated digestion and long-term storage at -18,4 and 25 °C was in the order: GE-P-O(SL)-GA > GE-P-O-GA > GE-P-GA.

CONCLUSION

As a result of its amphiphilic properties, SL strongly affected the physicochemical properties of probiotics and algal oil complex coacervates, resulting in higher stability and more effective lipolysis. Thus, the GE-P-O(SL)-GA can more effectively deliver probiotics and docosahexaenoic acid to the intestine, which provides a reference for the preparation of high-viability and high-lipolysis probiotics-algal oil microcapsules. © 2022 Society of Chemical Industry.

Lactulose in combination with soybean lecithin has a cryoprotective effect on probiotic taxa of bifidobacteria and Lactobacillaceae

Lactulose is commonly used in pharmacy for constipation and hepatic encephalopathy treatment. The prebiotic effect of lactulose is also often mentioned. However, its cryoprotective effect in combination with lecithin on the main representatives of probiotics has not been tested yet. The 12 taxa of bifidobacteria and Lactobacillaceae members were used for the purpose. These were mixed in a ratio of 1:1 with lactulose + lecithin (finally 5.0% and 1.25%, respectively; LL). The 25% glycerol (G+) solution and cultures themselves were applied as positive and negative controls, respectively. Bacterial suspensions were stored at a mild freezing temperature (-20°C) until the end of the experiment (210th day). The LL solution had a comparable (insignificant difference at the P-value = 0.05) cryoprotective effect as the positive control in five of six bifidobacteria and in three of six representatives of Lactobacillaceae. The better cryoprotective effect was revealed in other Lactobacillaceae. At the end of the experiment, the generally accepted therapeutic minimum (>107 Colony Forming Units/mL) was determined in LL solution in five bifidobacteria and four Lactobacillaceae strains. The presented results improve knowledge about long-term mild cryopreservation of the most commonly used probiotics and could contribute to developing new forms of (nutri)synbiotics.

Interaction between dietary fiber and bifidobacteria in promoting intestinal health

Bifidobacteria are considered as probiotics due to their role in promoting intestinal health, including regulating intestinal flora, controlling glycolipid metabolism, anti-colitis effects. Dietary fiber is considered as prebiotic favoring gut health. It also can be used as carbon source to support the growth and colonization of probiotics like bifidobacteria. However, because of genetic diversity, different bifidobacterial species differ in their ability to utilize dietary fiber. Meanwhile, dietary fiber with different structural properties has different effects on the bifidobacteria proliferation. The interaction between dietary fiber and bifidobacteria will consequently lead to a synergistic or antagonistic function in promoting intestinal health, therefore affecting the application of combined use of dietary fiber and bifidobacteria. In this case, we summarize the biological function of bifidobacteria, and their interaction with different dietary fiber in promoting gut health, and finally provide several strategies about their combined use.

Survivability of probiotics encapsulated in kelp nanocellulose/alginate microcapsules on microfluidic device

Probiotics are living microorganisms that can produce health benefits to the host only when they are ingested in sufficient quantities and reach the intestines active state. However, the external environment that probiotics face for a long time before administration and the low pH environment in the stomach after administration can greatly reduce their activity. In this work, we proposed a simple microfluidic encapsulation strategy to efficiently prepare the probiotics-loaded nanocellulose/alginate delivery system, which can improve the storage stability and gastrointestinal survival rate of probiotics. The microcapsules were found to be monodisperse, and the average particle size was<500 μm by observing the microstructure and macroscopic morphology. The kelp nanocellulose was cross-linked in the microcapsule and formed a dense surface with alginate. Through the simulated gastrointestinal digestion experiment, it was found that the survival of probiotics in microcapsules containing 0.5 % and 1.5 % kelp nanocellulose decreased by 1.77 log CFU/g and 1.65 log CFU/g respectively, which was significantly lower than that of nanocellulose-free microcapsules (3.70 log CFU/g). And all the treated groups could release probiotics above 7 log CFU/g after digesting intestinal juice for 6 h. Furthermore, through the storage experiment, it was found that the microcapsules with 1.5 % kelp nanocellulose could still release 8.07 log CFU/g probiotics after four weeks. The results provide a new strategy for probiotics processing and extensive high-value utilization of marine natural products.

Polymeric carriers for enhanced delivery of probiotics

Probiotics are live microorganisms (usually bacteria), which are defined by their ability to confer health benefits to the host, if administered adequately. Probiotics are not only used as health supplements but have also been applied in various attempts to prevent and treat gastrointestinal (GI) and non-gastrointestinal diseases such as diarrhea, colon cancer, obesity, diabetes, and inflammation. One of the challenges in the use of probiotics is putative loss of viability by the time of administration. It can be due to procedures that the probiotic products go through during fabrication, storage, or administration. Biocompatible and biodegradable polymers with specific moieties or pH/enzyme sensitivity have shown great potential as carriers of the bacteria for 1) better viability, 2) longer storage times, 3) preservation from the aggressive environment in the stomach and 4) topographically targeted delivery of probiotics. In this review, we focus on polymeric carriers and the procedures applied for encapsulation of the probiotics into them. At the end, some novel methods for specific probiotic delivery, possibilities to improve the targeted delivery of probiotics and some challenges are discussed.

The Development of a Melt-Extruded Shellac Carrier for the Targeted Delivery of Probiotics to the Colon

Hot melt extrusion (HME) is considered an efficient technique in developing solid molecular dispersions, and has been demonstrated to provide sustained, modified and targeted drug delivery resulting in improved bioavailability. However, most commercial enteric or pH-responsive polymers are relatively difficult to process or have high Glass Transition Temperature (Tg) values, making their use with temperature-sensitive drugs, probiotics or biologics not viable. Shellac is a natural thermoplastic, and after a review of current literature on the pharmaceutical HME process, a possible gap in the knowledge of the use of shellac to produce dosage forms by means of HME was identified. This work explores the possibility of SSB^® 55 pharmaceutical-grade shellac as a melt-extrudable encapsulation polymer to entrap freeze-dried probiotic powder and to determine bacterial cell viability post-processing. Well-defined strands were produced from the physical mixture of shellac and Biocare^® Bifidobacterium Probiotic. FTIR clarified that there are no significant interactions between the probiotic and polymer. All of the samples demonstrated less than 5% degradation over 24 h at pH of both 1.2 and 6.8. At pH 7.4, both loaded samples gave a similar dissolution trend with complete degradation achieved after 10–11 h. Following five-month storage, 57.8% reduction in viability was observed.

Preparation and characterization of alginate and gelatin microcapsules containing Lactobacillus rhamnosus

This paper describes the preparation and characterization of alginate beads coated with gelatin and containing Lactobacillus rhamnosus. Capsules were obtained by extrusion method using CaCl2 as cross linker. An experimental design was performed using alginate and gelatin concentrations as the variables investigated, while the response variable was the concentration of viable cells. Beads were characterized in terms of size, morphology, scanning electron microscopy (SEM), moisture content, Fourier Transform Infrared Spectrometry (FTIR), thermal behavior and cell viability during storage. The results showed that the highest concentration of viable cells (4.2 x 109 CFU/g) was obtained for 1 % w/v of alginate and 0.1 % w/v of gelatin. Capsules were predominantly spherical with a rough surface, a narrow size distribution ranging from 1.53 to 1.90 mm and a moisture content of 97.70 ± 0.03 %. Furthermore, FTIR and thermogravimetric analysis indicated an interaction between alginate-gelatin. Cell concentration of alginate/gelatin microcapsules was 105 CFU/g after 4 months of storage at 8 oC.

Potential role of probiotics in the management of gastric ulcer

Gastric ulcer is one of the most common chronic gastrointestinal diseases characterized by a significant defect in the mucosal barrier. Helicobacter pylori (H. pylori) infection and the frequent long-term use of non-steroidal anti-inflammatory drugs are major factors involved in gastric ulcer development. Acid inhibitors and antibiotics are commonly used to treat gastric ulcer. However, in the last few decades, the accumulating evidence for resistance to antibiotics and the side effects of antibiotics and acid inhibitors have drawn attention to the possible use of probiotics in the prevention and treatment of gastric ulcer. Probiotics are live microorganisms that when administered in adequate amounts confer health benefits on the host. Currently, the available experimental and clinical studies indicate that probiotics are promising for future applications in the management of gastric ulcers. This review aims to provide an overview of the general health benefits of probiotics on various systemic and gastrointestinal disorders with a special focus on gastric ulcer and the involved cellular and molecular mechanisms: i) Protection of gastric mucosal barrier; ii) upregulation of prostaglandins, mucus, growth factors and anti-inflammatory cytokines; iii) increased cell proliferation to apoptosis ratio; and iv) induction of angiogenesis. Finally, some of the available data on the possible use of probiotics in H. pylori eradication are discussed.

Improved quorum sensing capacity by culturing Vibrio harveyi in microcapsules

Microcapsule entrapped low density cells with culture (ELDCwc), different from free cell culture, conferred stronger stress resistance and improved cell viability of microorganisms. In this paper, the quorum sensing (QS) system of Vibrio harveyi was used to investigate changes when cells were cultured in microcapsules. Cells in ELDCwc group grew into cell aggregates, which facilitated cell-cell communication and led to increased bioluminescence intensity. Moreover, the luxS-AI-2 system, a well-studied QS signal pathway, was detected as both luxS gene and the AI-2 signaling molecule, and the results were analyzed with respect to QS capacity of unit cell. The V. harveyi of ELDCwc also showed higher relative gene expression and stronger quorum sensing capacity when compared with free cells. In conclusion, the confined microcapsule space can promote the cell aggregates formation, reduce cell-cell communication distance and increase local concentration of signal molecule, which are beneficial to bacterial QS.

Study on the effects of microencapsulated Lactobacillus delbrueckii on the mouse intestinal flora

OBJECTIVE

To evaluate the protective effects of microencapsulation on Lactobacillus delbrueckii by random, parallel experimental design.

MATERIALS AND METHODS

Lincomycin hydrochloride-induced intestinal malfunction mouse model was successfully established; then the L. delbrueckii microcapsule was given to the mouse. The clinical behaviour, number of intestinal flora, mucous IgA content in small intestine, IgG and IL-2 level in peripheral blood were monitored. The histological sections were also prepared.

RESULTS

The L. delbrueckii microcapsule could have more probiotic effects as indicated by higher bifidobacterium number in cecal contents. The sIgA content in microcapsule treated group was significantly higher than that in non-encapsulated L. delbrueckii treated group (p < 0.05). Intestine pathological damage of the L. delbrueckii microcapsule-treated group showed obvious restoration.

CONCLUSION

The L. delbrueckii microcapsules could relieve the intestinal tissue pathological damage and play an important role in curing antibiotic-induced intestinal flora dysfunction.

Evaluation of mucoadhesive coatings of chitosan and thiolated chitosan for the colonic delivery of microencapsulated probiotic bacteria

Probiotic bacteria were previously encapsulated in sub-100 µm Ca(2+) alginate microcapsules for enhanced survival in human gastrointestinal tract. The aim of this study is to evaluate the altered mucoadhesive property of the probiotic delivery system by coating it with mucoadhesive chitosan or thiolated chitosan, for prolonged retention in human colon. The results confirmed that cross-linking with calcium ions reduced the mucoadhesive property of alginate hydrogel, thus questioning the intrinsic mucoadhesiveness of uncoated systems. In contrast, chitosan and thiolated chitosan were found to be adsorbed on sub-100 µm Ca(2+) alginate microcapsules, and substantially improved the mucoadhesion performance of the system. The adhesion performance was correlated to the amount of mucoadhesive coating polymer adsorbed on the surface of the system. The coated system was demonstrated on HT29-MTX colonic epithelial monolayer to deliver markedly higher amount of probiotic bacteria to the in vitro model of colonic mucosa. Additionally, the coatings were also found to exert significantly stronger mucoadhesion to colonic mucosa tissue at slight acid neutral pH with less ambient water, which conforms to the physiological environment of the colon, thus supporting prolonged retention in this region.