Influence of Dehydrated Wheat/Rice Cereal Matrices on Probiotic Activity of Bifidobacterium animalis ssp. lactis BB-12®§

Evaluation of the Probiotic Properties of Lacticaseibacillus casei 431® Isolated from Food for Special Medical Purposes§

Research background

Increasing awareness of the importance of nutrition in health promotion and disease prevention has driven to the development of foods for special medical purposes (FSMPs). In this study, the probiotic strain Lacticaseibacillus paracasei ssp. paracasei (Lacticaseibacillus casei 431®) was incorporated into FSMPs to develop an innovative product. The aim was to investigate the influence of the FSMP matrix on the specific probiotic properties of L. casei 431® in vitro.

Experimental approach

A series of in vitro experiments were performed as part of the probiotic approach. After evaluation of antibiotic susceptibility profiles, functional properties such as survival under simulated gastrointestinal tract (GIT) conditions, bile salt deconjugation activities, cholesterol assimilation, antagonistic activity against spoilage bacteria and adhesion to Caco-2 cell line monolayers and extracellular matrix proteins were investigated.

Results and conclusions

The L. casei 431® strain, both the lyophilised strain and the strain isolated from the FSMP matrix, effectively survived the simulated adverse gastrointestinal conditions without significant effects of the food matrix. The effect of the FSMP matrix on the deconjugation activity of the bile salts of L. casei 431® was minimal; however, cholesterol assimilation was increased by 16.4 %. L. casei 431® had antibacterial activity against related lactic acid bacteria regardless of whether it was used in FSMPs or not. Conversely, the probiotic strain isolated from FSMP matrix had significantly higher inhibitory activity against six potential pathogens than the lyophilised culture. The autoaggregation ability of the L. casei 431® cells was not affected by the FSMP matrix. The adhesion of L. casei 431® bacterial cells to the extracellular matrix proteins was reduced after treatment with proteinase K, with the highest adhesion observed to laminin. The adhesion of L. casei 431® reduced the binding of E. coli 3014 by 1.81 log units and the binding of S. Typhimurium FP1 to Caco-2 cell lines by 1.85 log units, suggesting the potential for competitive exclusion of these pathogens.

Novelty and scientific contribution

The results support the positive effect of the FSMP matrix on the specific probiotic properties of L. casei 431®, such as antibacterial activity, bile salt deconjugation and cholesterol assimilation, while the incorporation of this probiotic strain adds functional value to the FSMPs. The synergistic effect achieved by the joint application of L. casei 431® and innovative FSMP matrix contributed to the development of the novel formulation of an improved functional food product with added value.

Safety Assessment of One Lactiplantibacillus plantarum Isolated from the Traditional Chinese Fermented Vegetables—Jiangshui

Lactiplantibacillus plantarum is a kind of extensively utilized probiotic species, which plays a critical role in the prevention of pathogenic bacteria and development of functional probiotics. Our group previously isolated one Lactiplantibacillus from Jiang Shui, a traditional Chinese fermented vegetable, which remarkably inhibited the growth of Aspergillus flavus. Herein, the safety of this isolate was assessed to ensure its application feasibility in food industry. Firstly, the phenotypic analyses including tolerance to low pH and bile salt, aggregation ability, and hemolytic activity detection, indicated the isolate could survive and colonize in the gastrointestinal tract, without hemolysin activity. The susceptibilities of the isolate to eight antibiotics and the absence of most resistance genes were demonstrated by agar disk diffusion and PCR, respectively. Furthermore, no mortality or toxicity was observed in mice by in vivo tests using gross autopsy, hematology, serum biochemistry, and HE-staining. Taken together, this study demonstrated the safety of Lactiplantibacillus plantarum WYH as a probiotic strain in terms of phenotypic analyses, absence of antimicrobial resistance and toxin-related genes, as well as mice toxicity test, while supported the prospect of applying isolate in suppression of fungal growth and mycotoxin biosynthesis.

A Lactic Acid Bacteria Consortium Impacted the Content of Casein-Derived Biopeptides in Dried Fresh Cheese

This study aimed to define a consortium of lactic acid bacteria (LAB) that will bring added value to dried fresh cheese through specific probiotic properties and the synthesis of bioactive peptides (biopeptides). The designed LAB consortium consisted of three Lactobacillus strains: S-layer carrying Levilactobacillus brevis D6, exopolysaccharides producing Limosilactobacillus fermentum D12 and plantaricin expressing Lactiplantibacillus plantarum D13, and one Enterococcus strain, Enterococcus faecium ZGZA7-10. Chosen autochthonous LAB strains exhibited efficient adherence to the Caco-2 cell line and impacted faecal microbiota biodiversity. The cheese produced by the LAB consortium showed better physicochemical, textural and sensory properties than the cheese produced by a commercial starter culture. Liquid chromatography coupled with matrix-assisted laser desorption/ionization-time of flight tandem mass spectrometry (LC-MALDI-TOF/TOF) showed the presence of 18 specific biopeptides in dried fresh cheeses. Their identification and relative quantification was confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using multiple reaction monitoring (MRM). The results also showed that their synthesis resulted mainly from β-casein and also α-S1 casein degradation by proteolytic activities of the LAB consortium. The designed LAB consortium enhanced the functional value of the final product through impact on biopeptide concentrations and specific probiotic properties.

Lyophilized alginate-based microspheres containing Lactobacillus fermentum D12, an exopolysaccharides producer, contribute to the strain's functionality in vitro

Lactobacillus (Limosilactobacillus) fermentum D12 is an exopolysaccharide (EPS) producing strain whose genome contains a putative eps operon. Whole-genome analysis of D12 was performed to disclose the essential genes correlated with activation of precursor molecules, elongation and export of the polysaccharide chain, and regulation of EPS synthesis. These included the genes required for EPS biosynthesis such as epsA, B, C, D and E, also gt, wzx, and wzy and those involved in the activation of the precursor molecules galE, galT and galU. Both the biosynthesis and export mechanism of EPS were proposed based on functional annotation. When grown on MRS broth with an additional 2% w/v glucose, L. fermentum D12 secreted up to 200 mg/L of a mixture of EPSs, whose porous structure was visualized by scanning electron microscopy (SEM). Structural information obtained by ¹HNMR spectroscopy together with composition and linkage analyses, suggested the presence of at least two different EPSs, a branched heteropolysaccharide containing t-Glcp and 2,6-linked Galf, and glycogen. Since recent reports showed that polysaccharides facilitate the probiotic-host interactions, we at first sought to evaluate the functional potential of L. fermentum D12. Strain D12 survived simulated gastrointestinal tract (GIT) conditions, exhibited antibacterial activity against enteropathogenic bacteria, adhered to Caco-2 cells in vitro, and as such showed potential for in vivo functionality. The EPS crude extract positively influenced D12 strain capacity to survive during freeze-drying and to adhere to extracellular matrix (ECM) proteins but did not interfere Caco-2 and mucin adherence when added at concentrations of 0.2, 0.5, and 1.0 mg/mL. Since the viable bacterial count of free D12 cells was 3 logarithmic units lower after the exposure to simulated GIT conditions than the initial count, the bacterial cells had been loaded into alginate for viability improvement. Microspheres of D12 cells, which were previously analyzed at SEM, significantly influenced their survival during freeze-drying and in simulated GIT conditions. Furthermore, the addition of the prebiotic substrates mannitol and lactulose improved the viability of L. fermentum D12 in freeze-dried alginate microspheres during 1-year storage at 4 °C compared to the control.

Effect of Lactobacillus rhamnosus on Physicochemical Properties of Fermented Plant-Based Raw Materials

To overcome texture and flavor challenges in fermented plant-based product development, the potential of microorganisms is generating great interest in the food industry. This study examines the effect of Lactobacillus rhamnosus on physicochemical properties of fermented soy, oat, and coconut. L. rhamnosus was combined with different lactic acid bacteria strains and Bifidobacterium. Acidification, titratable acidity, and viability of L. rhamnosus and Bifidobacterium were evaluated. Oscillation and flow tests were performed to characterize rheological properties of fermented samples. Targeted and untargeted volatile organic compounds in fermented samples were assessed, and sensory evaluation with a trained panel was conducted. L. rhamnosus reduced fermentation time in soy, oat, and coconut. L. rhamnosus and Bifidobacterium grew in all fermented raw materials above 10⁷ CFU/g. No significant effect on rheological behavior was observed when L. rhamnosus was present in fermented samples. Acetoin levels increased and acetaldehyde content decreased in the presence of L. rhamnosus in all three bases. Diacetyl levels increased in fermented oat and coconut samples when L. rhamnosus was combined with a starter culture containing Streptococcus thermophilus and with another starter culture containing S. thermophilus, L. bulgaricus and Bifidobacterium. In all fermented oat samples, L. rhamnosus significantly enhanced fermented flavor notes, such as sourness, lemon, and fruity taste, which in turn led to reduced perception of base-related attributes. In fermented coconut samples, gel firmness perception was significantly improved with L. rhamnosus. The findings suggest that L. rhamnosus can improve fermentation time and sensory perception of fermented plant-based products.

Effect of Lactobacillus rhamnosus on Physicochemical Properties of Fermented Plant-Based Raw Materials

Texture and flavor are currently the main challenges in the development of plant-based dairy alternatives. To overcome them, the potential of microorganisms for fermentation of plant-based raw materials is generating great interest in the food industry. This study examines the effect of Lactobacillus rhamnosus, LGG® (LGG® is a trademark of Chr. Hansen A/S) on the physicochemical properties of fermented soy, oat, and coconut. LGG® was combined with different lactic acid bacteria (LAB) strains and Bifidobacterium, BB-12® (BB-12® is a trademark of Chr. Hansen A/S). Acidification, titratable acidity, and growth of LGG® and BB-12® were evaluated. Oscillation and flow tests were performed to analyze the rheological properties of fermented samples. Acids, carbohydrates, and volatile organic compounds in fermented samples were identified, and a sensory evaluation with a trained panel was conducted. LGG® reduced fermentation time in all three bases. LGG® and BB-12® grew in all fermented raw materials above 107 CFU/g. LGG® had no significant effect on rheological behavior of the samples. Acetoin levels increased and acetaldehyde content decreased in the presence of LGG® in all three bases. Diacetyl levels increased in fermented oat and coconut samples when LGG® was combined with YOFLEX® YF-L01 and NU-TRISH® BY-01 (YOFLEX® and NU-TRISH® are trademarks of Chr. Hansen A/S). In all fermented oat samples, LGG® significantly enhanced fermented flavor notes, such as sourness, lemon, and fruity taste, which in turn led to reduced perception of the attributes related to the base. In fermented coconut samples, gel firmness perception was significantly improved in the presence of LGG®. These findings suggest supplementation of LAB cultures with LGG® to improve fermentation time and sensory perception of fermented plant-based products.

Review on Non-Dairy Probiotics and Their Use in Non-Dairy Based Products

Consumer demands for foods promoting health while preventing diseases have led to development of functional foods that contain probiotic bacteria. Fermented dairy products are good substrates for probiotic delivery, but the large number of lactose intolerant people, their high fat and cholesterol content and also due to the growing vegetarianism the consumers are seeking for alternatives. Therefore, researches have been widely studied the feasibility of probiotic bacteria in non-dairy products such as fruits, vegetables, and cereals. This review describes the application of probiotic cultures in non-dairy food products.