Unveiling the Probiotic Potential of Streptococcus thermophilus MCC0200: Insights from In Vitro Studies Corroborated with Genome Analysis

Synbiotics of encapsulated Limosilactobacillus fermentum K73 promotes in vitro favorable gut microbiota shifts and enhances short-chain fatty acid production in fecal samples of children with autism spectrum disorder

Modulation of the gut microbiota has emerged as a promising approach for addressing the gastrointestinal and neurodevelopmental symptoms associated with autism spectrum disorder (ASD). Consequently, this study aimed to evaluate the impact of four formulated synbiotics comprising Limoscilactobacillus fermentum K73, high-oleic palm oil and whey, on the gut microbiota composition of Colombian children with and without ASD. These components were encapsulated through high-shear emulsification and spray drying. The four synbiotics and their individual components were subjected to in vitro digestion and fermentation using samples of Colombian children gut microbiota. Short-chain fatty acids (SCFAs), including lactic, acetic, propionic, and butyric acids, were quantified using HPLC-DAD, while serotonin was determined by an ELISA kit after in vitro fermentations. Changes in microbial structure were assessed by the sequencing of the 16S rRNA gene via next-generation sequencing (NGS). The results revealed a decrease in the abundance of genera like Bacteroides and Dorea in ASD-associated samples after the treatment with the synbiotics. Conversely, an increase in the relative abundance of probiotic-related genera, including Lactobacillus, Streptococcus, and Anaerostipes, was observed. Furthermore, the analysis of SCFAs and serotonin indicated that the synbiotic intervention resulted in an elevated butyric acid and microbial serotonin synthesis, alongside a decrease in propionic acid, which is changes considered beneficial in the context of ASD. This evidence suggests that synbiotics of L. fermentum K73 could represent a promising live biotherapeutic strategy for modulating the gut microbiota of children with ASD.

Comparative genome analysis of 15 Streptococcus thermophilus strains isolated from Turkish traditional yogurt

Streptococcus thermophilus plays a pivotal role in yogurt fermentation, yet strains from traditional fermented products remain largely unexplored compared to their industrial counterparts. This study aimed to characterize the genomic diversity and functional potential of 15 S. thermophilus strains isolated from Turkish traditional yogurts, and to compare them with industrial strains. Through whole-genome sequencing and advanced bioinformatics analyses, we revealed distinct phylogenetic patterns and genetic features that differentiate these traditional strains from industrial isolates. The genomes (1.68-1.86 Mb) exhibited high genetic homogeneity (ANI > 98.69%) while maintaining significant functional diversity. Pan-genome analysis identified 1160 core genes and 5694 accessory genes, highlighting substantial genomic plasticity that enables niche adaptation. Our analysis uncovered several distinctive features: (1) unique phylogenetic clustering patterns based on both housekeeping genes and whole-genome SNPs, suggesting geographical isolation effects; (2) an extensive repertoire of carbohydrate-active enzymes (CAZymes), comprising 111 Glycoside Hydrolases, 227 Glycosyl Transferases, and 44 Carbohydrate Esterases and 13 Carbohydrate-Binding Modules, demonstrating sophisticated carbohydrate metabolism adaptation significantly enriched compared to industrial strains; (3) widespread GABA biosynthesis pathways in 8 strains, including complete gadB gene, indicating potential health-promoting properties; (4) multiple genomic islands containing genes for galactose utilization and stress response, suggesting specific adaptation to traditional fermentation environments; (5) diverse exopolysaccharide biosynthesis and bacteriocin gene clusters; and (6) widespread CRISPR-Cas systems with variable spacer content. Notably, we identified vanY glycopeptide resistance genes across all strains, with two strains additionally harboring vanT. These results reveal the genetic mechanisms behind S. thermophilus adaptation to traditional yogurt environments, offering valuable insights for developing starter cultures and preserving the unique qualities and potential health benefits of traditional dairy products.

Review on the Function, Substrate Affinity, and Potential Application of Bile Salt Hydrolase Originated from Probiotic Strains of Lactobacillus, Bifidobacterium, and Enterococcus

Bile salt hydrolase (BSH: EC.3.5.1.24) has been used as a biomarker for probiotics for an extended period. It is mostly present in the gut environment of vertebrates. Additionally, it influences the viability of probiotics. This biomarker is considered a promising nutritional supplement due to its unique ability to effectively address elevated blood cholesterol levels, a common issue in modern society. However, the commercialization of BSH has been limited by an incomplete understanding of the intestinal microbiota and the function of BSH. Hence, in this review, we aim to reveal the current advancements in BSH research and outline the necessary areas of investigation for future studies. The review highlights key findings related to the substrate affinity of BSH in probiotic bacteria and its BSH gene phylogeny that have been researched until today, suggesting further research regarding the differences in multiple BSH genes and corresponding differences in BSH affinity.

Characterization of Extracellular Vesicles from Streptococcus thermophilus 065 and Their Potential to Modulate the Immune Response

Bacteria can release membrane-derived nanoparticles made of lipid bilayers, so-called extracellular vesicles (EVs), which can carry diverse cargo and are important for microbe-microbe and microbe-host interactions. Here, we studied the production of EVs by Streptococcus thermophilus 065, the protein composition of the EVs, and how the produced EVs impact the immune response in vitro. Cultures of S. thermophilus grown for 6 h at 40 °C in M17 broth with 2% lactose reached high biomass yields and a high level of EVs quantified by lipophilic fluorescent dye staining. Proteome analysis of the isolated EVs revealed a high abundance of membrane-associated binding proteins of ABC transporters, ribosomal proteins, and glycolytic enzymes. In addition, phage proteins were found to be present in the EVs, which suggests a low-level expression of prophage genes during growth most likely supporting the release of EVs without causing cell lysis. The role of prophage activation was confirmed in an experiment with the addition of mitomycin C resulting in the expression of phage proteins including holin and endolysin causing a drop in culture OD and concomitant EV release. Subsequent in vitro immune assays using non-activated and activated human peripheral blood mononuclear cells (PBMCs) showed immune regulation in both cases upon exposure to S. thermophilus EVs and producer cells. This study shows the capacity of S. thermophilus EVs to act as immune modulators and opens the possibility for their use as postbiotics.

Antioxidant and Antimicrobial Properties of Probiotics: Insights from In Vitro Assays

Probiotics are microorganisms that provide health benefits at adequate doses and exhibit notable antioxidant and antimicrobial activities. These properties play crucial roles in combating chronic diseases linked to oxidative stress and antimicrobial resistance. This review aimed to summarize the antioxidant and antimicrobial properties of probiotics determined in in vitro studies and discuss mechanistic actions and analysis methods. The MEDLINE (PubMed), Web of Science, Scopus, Science Direct, and Embase databases were utilized. The included articles demonstrated the antioxidant and antimicrobial activities of both isolated and food matrix-associated probiotics, with the most common genera being Lactobacillus, Bifidobacterium, Saccharomyces, and Streptococcus. Antioxidant activity was the most studied property, yielding varied results attributed to evaluation tests and probiotic strain. Antibacterial activity was consistently reported in all studies. Additionally, fermentation with probiotic microorganisms improved the content and bioaccessibility of bioactive compounds. In conclusion, analysis results highlight the antioxidant and antimicrobial activity of probiotics reported in in vitro studies. They enhance bioactive content and bioaccessibility and produce novel beneficial metabolites during fermentation. These results reinforce the therapeutic promise of probiotics associated with plant matrices and indicate the need for clinical studies to confirm their efficacy in improving human health.

The Impact of Bioactive Molecules from Probiotics on Child Health: A Comprehensive Review

Background: This review investigates the impact of bioactive molecules produced by probiotics on child health, focusing on their roles in modulating gut microbiota, enhancing immune function, and supporting overall development. Key metabolites, including short-chain fatty acids (SCFAs), bacteriocins, exopolysaccharides (EPSs), vitamins, and gamma-aminobutyric acid (GABA), are highlighted for their ability to maintain gut health, regulate inflammation, and support neurodevelopment. Objectives: The aim of this review is to examine the mechanisms of action and clinical evidence supporting the use of probiotics and postbiotics in pediatric healthcare, with a focus on promoting optimal growth, development, and overall health in children. Methods: The review synthesizes findings from clinical studies that investigate the effects of probiotics and their metabolites on pediatric health. The focus is on specific probiotics and their ability to influence gut health, immune responses, and developmental outcomes. Results: Clinical studies demonstrate that specific probiotics and their metabolites can reduce gastrointestinal disorders, enhance immune responses, and decrease the incidence of allergies and respiratory infections in pediatric populations. Additionally, postbiotics-bioactive compounds from probiotic fermentation-offer promising benefits, such as improved gut barrier function, reduced inflammation, and enhanced nutrient absorption, while presenting fewer safety concerns compared to live probiotics. Conclusions: By examining the mechanisms of action and clinical evidence, this review underscores the potential of integrating probiotics and postbiotics into pediatric healthcare strategies to promote optimal growth, development, and overall health in children.

Comprehensive analysis of the CRISPR-Cas systems in Streptococcus thermophilus strains isolated from traditional yogurts

Phage resistance is crucial for lactic acid bacteria in the dairy industry. However, identifying all phages affecting these bacteria is challenging. CRISPR-Cas systems offer a resistance mechanism developed by bacteria and archaea against phages and plasmids. In this study, 11 S. thermophilus strains from traditional yogurts underwent analysis using next-generation sequencing (NGS) and bioinformatics tools. Initial characterization involved molecular ribotyping. Bioinformatics analysis of the NGS raw data revealed that all 11 strains possessed at least one CRISPR type. A total of 21 CRISPR loci were identified, belonging to CRISPR types II-A, II-C, and III-A, including 13 Type II-A, 1 Type III-C, and 7 Type III-A CRISPR types. By analyzing spacer sequences in S. thermophilus bacterial genomes and matching them with phage/plasmid genomes, notable strains emerged. SY9 showed prominence with 132 phage matches and 30 plasmid matches, followed by SY12 with 35 phage matches and 25 plasmid matches, and SY18 with 49 phage matches and 13 plasmid matches. These findings indicate the potential of S. thermophilus strains in phage/plasmid resistance for selecting starter cultures, ultimately improving the quality and quantity of dairy products. Nevertheless, further research is required to validate these results and explore the practical applications of this approach.