Influence of freezing temperature before freeze-drying on the viability of various Lactobacillus plantarum strains

Multistimuli responsive microcapsules produced by the prilling/vibration technique for targeted colonic delivery of probiotics

This study aimed to microencapsulate the probiotic strain Lactiplantibacillus plantarum 4S6R (basonym Lactobacillus plantarum) in both microcapsules and microspheres by prilling/vibration technique. A specific polymeric mixture, selected for its responsiveness to parallel colonic stimuli, was individuated as a carrier of microparticles. Although the microspheres were consistent with some critical quality parameters, they showed a low encapsulation efficiency and were discarded. The microcapsules produced demonstrated high yields (97.52%) and encapsulation efficiencies (90.06%), with dimensional analysis and SEM studies confirming the desired size morphology and structure. The results of thermal stress tests indicate the ability of the microcapsules to protect the probiotic. Stability studies showed a significant advantage of the microcapsules over non-encapsulated probiotics, with greater stability over time. The release study under simulated gastrointestinal conditions demonstrated the ability of the microcapsules to protect the probiotics from gastric acid and bile salts, ensuring their viability. Examination in a simulated faecal medium revealed the ability of the microcapsules to release the bacteria into the colon, enhancing their beneficial impact on gut health. This research suggests that the selected mixture of reactive polymers holds promise for improving the survival and efficacy of probiotics in the gastrointestinal tract, paving the way for the development of advanced probiotic products.

Recent Advances in the Understanding of Stress Resistance Mechanisms in Probiotics: Relevance for the Design of Functional Food Systems

In recent years, more and more scientific community, food producers, and food industry show increased interest in functional foods containing probiotics, which is a big challenge. The consumption of probiotics in the context of a balanced diet through the consumption of functional foods or through the intake of pharmaceutical preparations has proven to contribute to the improvement of human health, even contributing to the prevention of diseases. In order for probiotics to be considered suitable for consumption, they must contain a minimum concentration of viable cells, namely, at least 107 colony forming units of beneficial microbes per gram. Ensuring the viability of bacterial cells until the moment of consumption is the overriding priority of functional probiotic food manufacturers. Probiotic bacteria are subject to stress conditions not only during food manufacturing but also during gastrointestinal passage, which limit or even compromise their functionality. This paper first examines all the stressful conditions faced by probiotic cells in their production stages and related to the conditions present in the bioreactor fermentation and drying processes as well as factors related to the food matrix and storage. The stress situations faced by probiotic microorganisms during the gastrointestinal transit especially during stomach and intestinal residence are also analyzed. In order to understand the adaptation mechanisms of probiotic bacteria to gastrointestinal stress, intrinsic and adaptive mechanisms identified in probiotic strains in response to acid stress and to bile and bile acid stress are analyzed. In addition, improvement strategies for multiple stress tolerance of lactic acid bacteria through directions dealing with stress, accumulation of metabolites, use of protectants, and regulation of technological parameters are examined. Finally, the definition of postbiotics, inanimate microorganisms and/or their components conferring health benefits, is also introduced. Postbiotics include cell lysates, enzymes, and cell wall fragments derived from probiotic bacteria and may represent an alternative to the use of probiotics, when they do not tolerate stressful conditions.

Development of chitosan/carrageenan macrobeads for encapsulation of Paenibacillus polymyxa and its biocontrol efficiency against clubroot disease in Brassica crops

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, is one of the most important diseases of brassicas. The antagonistic bacterium Paenibacillus polymyxa ZF129 can suppress clubroot while its effectiveness is often unstable. To control clubroot more effectively, the macrobeads for controlled release of ZF129 were prepared using microencapsulation technology. Macrobeads with various ratios of chitosan (2 % w/w): carrageenan (0.3 % w/v) were prepared by an ionotropic gelation method and the bacteria ZF129 was loaded into macrobeads. The 1:1 chitosan: carrageenan showed the maximum swelling ratio (634 %), and the maximum survival rate (61.52 ± 1.12 %) after freeze-drying. Fourier transform infrared revealed the electrostatic interactions between chitosan and carrageenan. The macrobeads can efficiently release ZF129 strains into phosphate buffer solution and reach equilibrium in 48 h. The maximum number of bacteria cells to be released in the soil was observed after 25-30 days. The control efficacy of ZF129 macrobeads (chitosan: carrageenan, 1:1) and ZF129 culture against clubroot disease was 76.33 ± 3.65 % and 59.76 ± 4.43 % in greenhouse experiments, respectively and the control efficacy was calculated as 60.74 ± 5.00 % for ZF129 macrobeads and 40.94 ± 4.05 % for ZF129 culture under field experiments, respectively. The ZF129 macrobeads had significant growth-promoting effects on pak choi and Chinese cabbage. The encapsulation method described in this study is a prudent approach toward efficient biopesticides utilization with reduced environmental implications.

Effect of Lyoprotective Agents on the Preservation of Survival of a Bacillus cereus Strain PBG in the Freeze-Drying Process

Lyophilization is a widely employed long-term preservation method in which the bacterial survival rate largely depends on the cryoprotectant used. Bacillus cereus strain PBC was selected for its ability to thrive in environments contaminated with arsenic, lead, and cadmium, tolerate 500 ppm of free cyanide, and the presence of genes such as ars, cad, ppa, dap, among others, associated with the bioremediation of toxic compounds and enterotoxins (nheA, nheB, nheC). Following lyophilization, the survival rates for Mannitol 2.5%, Mannitol 10%, and Glucose 1% were 98.02%, 97.12%, and 96.30%, respectively, with the rates being lower than 95% for other sugars. However, during storage, for the same sugars, the survival rates were 78.71%, 97.12%, and 99.97%, respectively. In the cake morphology, it was found that the lyophilized morphology showed no relationship with bacterial survival rate. The best cryoprotectant for the PBC strain was 1% glucose since it maintained constant and elevated bacterial growth rates during storage, ensuring that the unique characteristics of the bacterium were preserved over time. These findings hold significant implications for research as they report a new Bacillus cereus strain with the potential to be utilized in bioremediation processes.

3D printing of microencapsulated Lactobacillus rhamnosus for oral delivery

3D Printing is an innovative technology within the pharma and food industries that allows the design and manufacturing of novel delivery systems. Orally safe delivery of probiotics to the gastrointestinal tract faces several challenges regarding bacterial viability, in addition to comply with commercial and regulatory standpoints. Lactobacillus rhamnosus CNCM I-4036 (Lr) was microencapsulated in generally recognised as safe (GRAS) proteins, and then assessed for robocasting 3D printing. Microparticles (MP-Lr) were developed and characterised, prior to being 3D printed with pharmaceutical excipients. MP-Lr showed a size of 12.3 ± 4.1 µm and a non-uniform wrinkled surface determined by Scanning Electron Microscopy (SEM). Bacterial quantification by plate counting accounted for 8.68 ±0.6 CFU/g of live bacteria encapsulated within. Formulations were able to keep the bacterial dose constant upon contact with gastric and intestinal pH. Printlets consisted in oval-shape formulations (15 mm × 8 mm × 3.2 mm) of ca. 370 mg of total weight, with a uniform surface. After the 3D printing process, bacterial viability remained even as MP-Lr protected bacteria alongside the process (log reduction of 0.52, p>0.05) in comparison with non-encapsulated probiotic (log reduction of 3.05). Moreover, microparticle size was not altered during the 3D printing process. We confirmed the success of this technology for developing an orally safe formulation, GRAS category, of microencapsulated Lr for gastrointestinal vehiculation.

Preparation and Evaluation of a Dosage Form for Individualized Administration of Lyophilized Probiotics

Probiotics have been used in human and veterinary medicine to increase resistance to pathogens and provide protection against external impacts for many years. Pathogens are often transmitted to humans through animal product consumption. Therefore, it is assumed that probiotics protecting animals may also protect the humans who consume them. Many tested strains of probiotic bacteria can be used for individualized therapy. The recently isolated Lactobacillus plantarum R2 Biocenol™ has proven to be preferential in aquaculture, and potential benefits in humans are expected. A simple oral dosage form should be developed to test this hypothesis by a suitable preparation method, i.e., lyophilization, allowing the bacteria to survive longer. Lyophilizates were formed from silicates (Neusilin® NS2N; US2), cellulose derivates (Avicel® PH-101), and saccharides (inulin; saccharose; modified starch® 1500). They were evaluated for their physicochemical properties (pH leachate, moisture content, water absorption, wetting time, DSC tests, densities, and flow properties); their bacterial viability was determined in conditions including relevant studies over 6 months at 4 °C and scanned under an electron microscope. Lyophilizate composed of Neusilin® NS2N and saccharose appeared to be the most advantageous in terms of viability without any significant decrease. Its physicochemical properties are also suitable for capsule encapsulation, subsequent clinical evaluation, and individualized therapy.

Preparation and Application of Directed Vat Set Indigenous Freeze-Drying Lentilactobacillus hilgardii Q19 Starter in Winemaking

In order to prepare a better direct vat set for malolactic fermentation (MLF) in high ethanol and low pH wines, the high-ethanol- and low-temperature-tolerant strain Lentilactobacillus hilgardii Q19, which was isolated from the eastern foothill of the Helan Mountain wine region in China, was used to prepare a direct vat set by vacuum freeze-drying. A superior freeze-dried lyoprotectant was obtained to create the starting culture by selecting, combining, and optimizing numerous lyoprotectants with higher protection for Q19 by using a single-factor experiment and response surface approach. Finally, the Lentilactobacillus hilgardii Q19 direct vat set was inoculated in Cabernet Sauvignon wine to carry out MLF on a pilot scale, with commercial starter culture Oeno1 as control. The volatile compounds, biogenic amines, and ethyl carbamate content were analyzed. The results showed that a combination of 8.5 g/100 mL skimmed milk powder, 14.5 g/100 mL yeast extract powder, and 6.0 g/100 mL sodium hydrogen glutamate offered better protection; with this lyoprotectant, there were (4.36 ± 0.34) × 10¹¹ CFU/g cells after freeze-drying, and it showed an excellent ability to degrade L-malic acid and could successfully finish MLF. In addition, in terms of aroma and wine safety, compared with Oeno1, the quantity and complexity of volatile compounds were increased after MLF, and biogenic amines and ethyl carbamate were produced less during MLF. We conclude that the Lentilactobacillus hilgardii Q19 direct vat set could be applied as a new MLF starter culture in high-ethanol wines.

The Effect of Decreased Ca++/Mg++ ATPase Activity on Lactobacillus delbrueckii subsp. bulgaricus sp1.1 Survival during Spray Drying

Compared with the commonly used technique of freeze-drying, spray drying has lower energy costs. However, spray drying also has a fatal disadvantage: a lower survival rate. In this study, the survival of bacteria in a spray-drying tower decreased as the water content was reduced. The water content of 21.10% was the critical point for spray drying Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) sp1.1 based on sampling in the tower. Based on the relationship between the moisture content of spray drying and the survival rate, the water content of 21.10% was also the critical point for the change in the survival rate during spray drying. Proteomic analysis was used to investigate the reasons for L. bulgaricus sp1.1 inactivation during and after spray drying. Gene Ontology (GO) enrichment revealed that differentially expressed proteins were mainly associated with the cell membrane and transport. In particular, proteins related to metal ion transport included those involved in the transport of potassium, calcium and magnesium ions. The protein-protein interaction (PPI) network revealed that Ca⁺⁺/Mg⁺⁺ adenosine triphosphatase (ATPase) may be a key protein. Ca⁺⁺/Mg⁺⁺ ATPase activity decreased substantially during spray drying (p < 0.05). Supplementation with Ca⁺⁺ and Mg⁺⁺ significantly increased the expression of ATPase-related genes and enzyme activity (p < 0.05). The Ca⁺⁺/Mg⁺⁺ ATPase activity of L. bulgaricus sp1.1 was enhanced by increasing the intracellular Ca⁺⁺ or Mg⁺⁺ concentration, thus increasing the survival of spray-dried LAB. Bacterial survival rates were increased to 43.06% with the addition of Ca⁺⁺ and to 42.64% with the addition of Mg⁺⁺, respectively. Ca⁺⁺/Mg⁺⁺ ATPase may be the key to the damage observed in spray-dried bacteria. Furthermore, the addition of Ca⁺⁺ or Mg⁺⁺ also reduced bacterial injury during spray drying by enhancing the activity of Ca⁺⁺/Mg⁺⁺ ATPase.

Influence of Temperature during Freeze-Drying Process on the Viability of Bifidobacterium longum BB68S

Maintaining optimum temperature during freeze-drying is crucial to ensuring the viability of strains. In this study, we evaluated the effect of pre-freezing, sublimation and desorption temperatures on the viability of Bifidobacterium longum BB68S (BB68S). Moreover, we examined the water content, water activity, enzyme activities, and scanning electron microscope of BB68S to explore mechanisms underpinning the effect of temperature on viability. Our analyses revealed the highest survival rates of BB68S collected after pre-freezing and sublimation drying at -40 °C (94.9 ± 2.2%) and -10 °C (65.4 ± 3.8%), respectively. Additionally, response surface methodology demonstrated that the optimum conditions for freeze-drying of BB68S were pre-freezing temperature at -45.52 °C and sublimation temperature at -6.58 °C, and the verification test showed that survival rates of BB68S could reach 69.2 ± 3.8%. Most of the vitality loss occurred during the sublimation drying phase. Further studies showed that different sublimation temperatures affected water content and activity, β-galactosidase, lactate dehydrogenase, Na⁺-K⁺-ATP and Ca²⁺-Mg²⁺-ATP activities. In conclusion, the temperature during freeze-drying, especially sublimation temperature, is a key factor affecting the survival rate of BB68S, and the vitality loss during freeze-drying process might be due to compromised cell membrane integrity and permeability.

Journey of the Probiotic Bacteria: Survival of the Fittest

This review aims to bring a more general view of the technological and biological challenges regarding production and use of probiotic bacteria in promoting human health. After a brief description of the current concepts, the challenges for the production at an industrial level are presented from the physiology of the central metabolism to the ability to face the main forms of stress in the industrial process. Once produced, these cells are processed to be commercialized in suspension or dried forms or added to food matrices. At this stage, the maintenance of cell viability and vitality is of paramount for the quality of the product. Powder products requires the development of strategies that ensure the integrity of components and cellular functions that allow complete recovery of cells at the time of consumption. Finally, once consumed, probiotic cells must face a very powerful set of physicochemical mechanisms within the body, which include enzymes, antibacterial molecules and sudden changes in pH. Understanding the action of these agents and the induction of cellular tolerance mechanisms is fundamental for the selection of increasingly efficient strains in order to survive from production to colonization of the intestinal tract and to promote the desired health benefits.

Protective effects of whey protein hydrolysate on Bifidobacterium animalis ssp. lactis Probio-M8 during freeze-drying and storage

We evaluated the potential of whey protein hydrolysate as a lyoprotectant for maintaining the cell viability of Bifidobacterium animalis ssp. lactis Probio-M8 during freeze-drying and subsequent storage. The moisture content and water activity of the lyophilized samples treated by different concentrations of whey protein hydrolysate were ≤5.23 ± 0.33 g/100 g and ≤0.102 ± 0.003, respectively. During storage at 25°C and 30°C, whey protein hydrolysate had a stronger protective effect on B. lactis Probio-M8 than the same concentration of whey protein. Using the Excel tool GinaFit, we estimated the microbial inactivation kinetics during storage. Whey protein hydrolysate reduced cell damage caused by an increase in temperature. Whey protein hydrolysate could protect cells by increasing the osmotic pressure as a compatible solute. Whey protein hydrolysate improved cell membrane integrity and reduced the amounts of reactive oxygen species and malondialdehyde produced. The findings indicated that whey protein hydrolysate was a novel antioxidant lyoprotectant that could protect probiotics during freeze-drying and storage.

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

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Saccharides assessed as combined cryoprotectant, preservative and prebiotic.

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Application is freeze dried topical probiotic of Lactobacillus plantarum.

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Inulin was best as cryoprotectant, but did not protect cells over storage.

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Best combined performance using sucrose with storage at 4 °C.

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Room temperature storage only feasible with skimmed milk (positive control).

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.

Efficacy of the incorporation between self-encapsulation and cryoprotectants on improving the freeze-dried survival of probiotic bacteria

AIMS

This study aimed to improve the viability of probiotic bacteria during freeze-drying by the combination of self-encapsulation and cryoprotectants.

METHODS AND RESULTS

Lactiplantibacillus plantarum VAL6 and Lactobacillus acidophilus VAR1 were exposed to environmental stresses including temperature, pH, and increased CO₂ concentration before performing freeze-drying with the addition of cryoprotectants. The results proved that tested stresses can stimulate the bacteria to synthesize more extracellular polymeric substances to form self-encapsulation that increases their freeze-dried viability. In combination with cryoprotectants to form double-layered microencapsulation, L. plantarum VAL6 stressed at pH 3.5 in combination with whey protein isolate could achieve the highest Improving Cell Viability of 4,361 fold, while L. acidophilus VAR1 stressed at 25^o C in combination with alginate gave a maximum Improving Cell Viability of 73.33 fold.

CONCLUSIONS

The combination of self-encapsulation and cryoprotectants significantly improves the freeze-dried viability of probiotics.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report that uses environmental stress to stimulate EPS synthesis for self-encapsulation formation combined with the addition of cryoprotectants to enhance to the freeze-dried survival of probiotics. This could be a novel approach in improving the viability of probiotic strains for various applications.