Survival of Bifidobacterium strains in organic fermented milk is improved as a result of membrane fatty acid composition

Probiotic Fermented Goat's and Sheep's Milk: Effect of Type and Dose of Collagen on Survival of Four Strains of Probiotic Bacteria during Simulated In Vitro Digestion Conditions

Microbial tolerance of digestive stresses depends not only on the bacterial strain but also on the structure and physicochemical properties of the supply chain and the foods that contain it. In the present study, we aimed to evaluate the effects of the type of milk (ovine, caprine) and the type and dose of collagen on the viability of four probiotic strains, Lacticaseibacillus paracasei L-26, Lacticaseibacillus casei 431, Lactobacillus acidophilus LA-5, and Lacticaseibacillus rhamnosus Lr-32, during in vitro gastrointestinal digestion. The highest survival rate under simulated in vitro digestion conditions compared to the number of cells before digestion was found in two strains, L. casei and L. paracasei, where survival rates were greater than 50% in each batch. The survival rate of the L. rhamnosus strain ranged from 41.05% to 64.23%. In caprine milk fermented by L. acidophilus, a higher survival rate was found in milk with 1.5% hydrolysate than the control, by about 6%. Survival of the L. rhamnosus strain was favorably affected by the 3% addition of bovine collagen in caprine milk, which increased survival by about 14% compared to the control sample. Adding 3% of hydrolysate to sheep's and goat's milk enhanced the survival of the L. rhamnosus strain by 3% and 19%, respectively. This study reports that fermented caprine and ovine milk may be suitable matrices for the probiotic supply of commercial dairy starter cultures and promote gut homeostasis.

Improvement of Freeze-Dried Survival of Lactiplantibacillus plantarum Based on Cell Membrane Regulation

The cell membrane of Lactiplantibacillus plantarum is a key structure for cell survival. In this study, we aimed to improve the lyophilization resistance of L. plantarum by regulating the cell membrane structure. Unsaturated fatty acids or cell membrane-regulating substances were added during culturing to determine their effect on the composition of cell membrane fatty acids and the survival rate of the cells after freeze-drying. The results showed that Tween 80, β-carotene and melatonin increased the lyophilization survival rate of L. plantarum by 9.44, 14.53, and 18.34%, respectively. After adding a lyophilization protective agent at a concentration of 21.49% at a 1:1 ratio, a combination of Tween 80, melatonin, and β-carotene was added to regulate the cell membrane, which increased the lyophilization survival rate by 32.08–86.05%. This study proposes new research directions and ideas for improving the survival rate of probiotics for industrial production.

Influence of guabiroba pulp (campomanesia xanthocarpa o. berg) added to fermented milk on probiotic survival under in vitro simulated gastrointestinal conditions

In fermented milks inoculated with two thermophilic strains (Lactobacillus bulgaricus and Streptococcus thermophilus), guabiroba pulp (Campomanesia xanthocarpa O. Berg) was added in different concentrations: 5% (I5 sample) and 10% (I10 sample), compared to a control sample, with no pulp addition. In these fermented milks, Bifidobacterium BB-12 was added and the samples were submitted to a progressive gastrointestinal simulation in vitro. The cells count was performed, including the survival rates for all the progressive steps of the simulated digestion. Total phenolic content (TPC) and antioxidant activity analysis by FRAP (Ferric Reducing Antioxidant Power) and DPPH (2,2-diphenyl-1-picrylhydrazyl) were performed in all the gastrointestinal steps. Before and during the entire gastrointestinal tract, the Bifidobacterium BB-12 count was 8-9 log CFU g^-1, above the recommended for a probiotic product, with a highlight in intestinal colon steps. The I10 sample showed the highest viable cell count, the highest total phenolic content and antioxidant activity throughout the entire gastric steps (p < 0.05). The fermented milk proved to be an effective matrix for the probiotic stability and incorporation of guabiroba components. Bioactive compounds present in the guabiroba pulp may have occasioned a prebiotic and protective effect on Bifidobacterium BB-12 after gastric conditions. The possible bioconversion of these compounds in more active forms can contribute to the absorption in epithelial cells, enhancing fermented milks with guabiroba pulp as important sources of dietary accessible bioactive compounds.

Novel bifidobacteria strains isolated from nonconventional sources. Technological, antimicrobial and biological characterization for their use as probiotics

AIM

To characterize four novel autochthonous bifidobacteria isolated from monkey faeces and a Bifidobacterium lactis strain isolated from chicken faeces by evaluating their technological and biological/functional potential to be used as probiotics. Different stressors, including food process parameters and storage, can affect their viability and functionality.

METHODS AND RESULTS

The resistance to frozen storage, tolerance to lyophilization and viability during storage, thermal, acidic and simulated gastric resistance, surface hydrophobicity and antimicrobial activity against pathogens were studied. Bifidobacterium lactis Bb12 and INL1 were used as reference strains. The results obtained demonstrated that the new isolates presented strain-dependent behaviour. Good results were obtained for thermal resistance, frozen storage at -80°C and lyophilized powders maintained at 5°C. Cell viability during refrigerated storage was higher when the strains were resuspended in milk at pH 5·0 than at 4·5. The surface hydrophobicity ranged between 7 and 98% depending on the strain. The simulated gastric resistance was improved for the strains incorporated in cheese. Regarding antimicrobial activity, bifidobacteria isolated from monkey presented higher inhibitory capacity than the reference strains.

CONCLUSION

This research provides a deeper insight into new strains of bifidobacteria isolated from primates and chicken that have not been previously characterized for their potential use in dairy products and confirm the most robust stress tolerance of B. lactis.

SIGNIFICANCE AND IMPACT OF THE STUDY

The possibility of expanding the available bifidobacteria with the potential to be added to a probiotic food necessarily implies characterizing them from different points of view, especially when considering unknown species. For monkey isolates (which showed higher antimicrobial activity against pathogens), more in-depth knowledge is needed before applying strategies to improve their performance. On the contrary, the chicken isolate B. lactis P32/1 showed similar behaviour to the references B. lactis strains; therefore, it could be considered as a potential probiotic candidate.

Technological Properties of Bifidobacterial Strains Shared by Mother and Child

Technological processes in the dairy industry and the further passage through the gastrointestinal tract could impair viability and functionality of probiotic bifidobacteria. In the present work, the growth in milk of nine bifidobacterial strains shared by mother and child, their survival to freeze-drying and cold storage, and their behavior in a model cheese were investigated. All the strains exhibited high stability to the technological conditions studied when compared with two commercial strains. Bifidobacterium breve INIA P734 and Bifidobacterium bifidum INIA P671 as adjunct cultures maintained high stability during manufacture and ripening of cheese. Both strains showed, at the end of ripening period, resistance to simulated gastrointestinal conditions. Moreover, their presence did not affect negatively the quality of cheese. B. breve INIA P734 and B. bifidum INIA P671 could be considered as potential candidates for their use in cheese as adjunct cultures.

Staying alive: growth and survival of Bifidobacterium animalis subsp. animalis under in vitro and in vivo conditions

Members of the Bifidobacterium genus are widely used as probiotics in fermented milk products. Bifidobacterium animalis subsp. animalis CNCM I-4602 grows and survives poorly in reconstituted skimmed milk (RSM). Availing of genome and transcriptome information, this poor growth and survival phenotype in milk was substantially improved by the addition of certain compounds, such as yeast extract, uric acid, glutathione, cysteine, ferrous sulfate, and a combination of magnesium sulfate and manganese sulfate. Carbohydrate utilization of CNCM I-4602 was also investigated, allowing the identification of several carbohydrate utilization gene clusters, and highlighting this strain's inability to utilize lactose, unlike the type strain of this subspecies, B. animalis subsp. animalis ATCC25527 and the B. animalis subsp. lactis subspecies. In addition, the ability of B. animalis subsp. animalis CNCM I-4602 to colonize a murine model was investigated, which showed that this strain persists in the murine gut for a period of at least 4 weeks. Associated in vivo transcriptome analysis revealed that, among other genes, a gene cluster encoding a predicted type IVb tight adherence (Tad) pilus was upregulated, indicating that this extracellular structure plays a role in the colonization/adaptation of the murine gastrointestinal tract by this strain.