Dynamics of thermophilic starters in PDO Comté cheese: Insights from viability qPCR.

The valorization of food processing by-products is a key strategy for advancing sustainability in the agri-food sector. This study developed a fermented milk product incorporating tomato powder (TP) obtained from surplus tomatoes not meeting retail appearance standards. Four yogurt formulations were prepared containing TP (2% and 4%, w/v) and two controls with skim milk powder adjusted to equivalent total solids. Samples were inoculated with a commercial starter culture and fermented at 42 °C to a final pH of 4.6. TP addition did not hinder fermentation but altered acidification kinetics, as the 4% TP yogurt exhibited a faster initiation (Tm ≈ 80 vs. 120 min in the control) yet a slower rate of pH decline (Vmax = 0.009 vs. 0.019 pH units/min). TP-fortified yogurts exhibited higher water holding capacity (98% vs. 83%), increased firmness (87 g vs. 47 g), and substantially elevated viscosity (63,000–68,000 mPa·s) while lycopene enrichment enhanced color attributes. Viable counts of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus remained within typical ranges (~6.8 and ~4.9 log CFU/g, respectively, after 24 h), confirming that TP did not compromise microbial activity. Overall, incorporating TP improved structural and functional properties while simultaneously providing tomato-derived antioxidants and promoting a sustainable, circular utilization of surplus tomato streams in fermented dairy products.

This study evaluated the effects of different concentrations (0.25%, 0.5%, and 1.0% w/w) of highly purified (90%) β-glucan (scleroglucan—SCGL) produced by Sclerotium rolfsii on the physicochemical, rheological, microbiological, and sensory properties of full-fat yoghurt (3.2% fat). The fermentation dynamics, titratable acidity, apparent viscosity, hardness, adhesiveness, colour, microstructure, and volatile compound profiles of the studied yoghurts were analysed. The addition of SCGL increased gel hardness and viscosity, while preserving its pseudoplastic flow behaviour (n = 0.10–0.15). In samples containing 1.0% SCGL, yield stress (τ0) increased from 0 Pa in the control to 739 Pa after 28 days of storage, pointing to the formation of a dense protein–polysaccharide network. The analysed polysaccharide slowed down lactose hydrolysis and acidification, but increased the counts of Streptococcus thermophilus (7.7 log CFU·g−1) compared to the control (5.8 log CFU·g−1). The volatile compound analysis showed increased acetaldehyde (5.6 mg·L−1) and diacetyl (5.0 mg·L−1) levels and reduced acetoin (~1.0 mg·L−1) concentration, which enhanced the intensity of the buttery aroma. The sensory evaluation revealed that yoghurts containing 1% SCGL had the most desirable smooth consistency and a balanced, fresh aroma, whereas yoghurts with lower SCGL concentrations (0.25–0.5%) were characterised by a mealy mouthfeel and thinner consistency. Scleroglucan proved to be an effective natural stabiliser and flavour modulator that improved the structure, stability, and sensory quality of full-fat yoghurts.

Plant-based yogurts are preferred as natural and healthy alternatives. This study provides a comprehensive bibliometric analysis of soy-based yogurt. The changes by fermentation of soy yogurt, starters, and potential effects of soy yogurt on the intestines were evaluated. A Web of Science database was used to analyze 76 "soy yogurt-isoflavone related (A)" articles (1998-2025) and 48 "soy yogurt-amino acid related (B)" (1997-2025), and 14 "soy yogurt-gut microbiota related (C)" articles (2016-2025) using the Bibliometrix Package and Biblioshiny interface in RStudio. Studies A have been published primarily in Food Bioscience, the Journal of Food Science, and The Science of Food and Agriculture. Studies on B have been published primarily in Food Chemistry, Food Research International, and the International Journal of Food Microbiology. The authors who have conducted the most research on the subject are Astheimer L.B. (for A) and Li (for B). According to abstract keywords, genistein and daidzein were studied in A, while "amino acids and free amino acids" were frequently associated with soy yogurt. "Yogurt and fermented" was listed in the motor themes, while "soy, milk, soymilk, fermentation, acid, probiotic, and bacteria" was listed in the basic themes. Daidzein, genistein, glycosidase, protein isolates, Streptococcus thermophilus, Lactobacillus acidophilus, and Lactobacillus delbrueckii were among the trending topics. "Gut microbiota" and "microbiota modulation" are participate in the most used term in C. This study is among the articles that comprehensively address alternative functional protein sources in sustainability. Journal performance, keywords, thematic development and author statuses will support new research on soy yogurt.

Abstract Research into bio preservation using lactic acid bacteria (LAB) as alternatives to synthetic additives has seen significant growth in response to the increasing consumer demand for natural food preservatives. In this study, the biochemical properties and antibacterial activity of Streptococcus thermophilus isolates isolated from commercial yogurt brands were thoroughly evaluated for use in bio preservation. Twenty isolates were obtained from local markets and various yogurt brands and subjected to comprehensive biochemical characterization. Their antimicrobial activity against twelve pathogenic bacterial strains was evaluated. Biochemical analysis demonstrated that all isolates exhibited the intrinsic characteristics of S. thermophilus : catalase-negative, oxidase-negative, and alpha-hemolytic, with optimal growth conditions ranging from 30 to 45°C and remarkable tolerance to a wide range of pH (4.2–9.6) and salt concentrations (2–4% NaCl). All strains demonstrated the ability to ferment lactose, sucrose, glucose, and maltose, but were unable to metabolize mannitol, melibiose, raffinose, and sorbitol. Antimicrobial screening showed that 70% of the isolates (14/20) exhibited significant inhibitory effects, with preferential activity against Gram-positive bacteria (overall inhibition rate: 33.3%). Listeria monocytogenes showed moderate sensitivity (inhibition zone of 1.7 cm), while S. aureus showed the highest sensitivity, with inhibition zones extending to 2.3 cm. A secondary screening based on acidification capacity found strain S5 from Kefil yogurt as superior, exhibiting the highest antibacterial activity (5.7 cm inhibition zone) along with the highest acidity yield (1.14%). These results confirm the enormous potential of yogurt-derived Streptococcus thermophilus strains as natural biopreservative. Furthermore, they address consumer demands for clean alternatives to synthetic preservatives by providing a systematic framework for strain selection and optimization in food preservation applications.

Potential biomarkers for human Ascending aortic aneurysm identified through metagenomic and metabolomic analyses: A case-control study.

Mixing and fermenting chickpea and almond milk analogues to produce probiotic yoghurt analogues.

Ribonucleotide reductases (RNRs) catalyze the conversion of ribonucleotides to deoxyribonucleotides. In the majority of cases, RNR activity is allosterically regulated by the cellular 2′-deoxyadenosine 5′-triphosphate (dATP)/adenosine 5′-triphosphate (ATP) ratio. To investigate allosteric activity regulation in anaerobic or class III (glycyl radical containing) RNRs, we determine cryo–electron microscopy structures of the class III RNR from Streptococcus thermophilus (StNrdD). We find that StNrdD’s regulatory “cone” domains adopt markedly different conformations depending on whether the activator ATP or the inhibitor dATP is bound and that these different conformations alternatively position an “active site flap” toward the active site (ATP-bound) or away (dATP-bound). In contrast, the position of the glycyl radical domain is unaffected by the cone domain conformations, suggesting that StNrdD activity is regulated through control of substrate binding rather than control of radical transfer. Hydrogen-deuterium exchange mass spectrometry and mutagenesis support the structural findings. In addition, our structural data provide insight into the molecular basis by which ATP and dATP binding lead to the observed differential cone domain conformations.

The study analyzes the influence of different concentrations of mixed starter cultures of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus on the physicochemical characteristics of natural yogurt. Yogurt was prepared from milk with 3.5 % fat, to which starter cultures were added at proportions of 0.5 %, 1 %, and 2 % of the milk volume for three separate samples. After homogenization and incubation, the obtained samples were analyzed from a physicochemical point of view. The different concentrations of the starter culture have a direct impact on the quality and physicochemical properties of the yogurt, affecting parameters such as acidity, texture, syneresis, and flavor. The determinations carried out included titratable acidity, fat content, moisture, and pH. The results obtained highlight how the level of inoculation with starter cultures influences the final quality of natural yogurt.

Probiotics are widely used in paediatrics, but efficacy varies by strain and indication. In 2023, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Special Interest Group on Gut Microbiota and Modifications issued strain-specific recommendations for gastrointestinal disorders. This review summarises studies published since 2024 to assess whether new evidence warrants changes to these recommendations. Lacticaseibacillus rhamnosus GG (LGG) and Saccharomyces boulardii are recommended for preventing antibiotic-associated diarrhoea. LGG, S. boulardii, Limosilactobacillus reuteri DSM 17938, or the combination of L. rhamnosus 19070-2 and L. reuteri DSM 12246 may be considered in acute gastroenteritis. For infant colic, recommendations include L. reuteri DSM 17938 or Bifidobacterium lactis BB-12 in breast-fed infants; for functional abdominal pain, L. reuteri DSM 17938 or LGG. No probiotics are recommended for constipation. For prevention of necrotising enterocolitis, weak recommendations include LGG or a combination of B. infantis BB-02, B. lactis BB-12 and Streptococcus thermophilus TH-4. There is no recommendation for or against probiotic-supplemented formulas. Recent trials have not provided sufficient evidence to justify changes to the ESPGHAN recommendations. Evidence for probiotic use in paediatrics is confined to a few strains and indications. Larger multicentre studies with standardised preparations and clearly defined outcomes are still needed.

Soft cheeses provide an ideal matrix for bacterial growth, serving as a medium for inoculating starter microorganisms like Lactobacillus. This study aimed to evaluate the biochemical, histopathological, and immunohistochemical effects of white soft cheese inoculated with Lactobacillus helveticus, Lactobacillus rhamnosus, and Streptococcus thermophilus S3855 on male reproductive health in albino rats. Forty male Albino rats, divided into five isolated groups, and fed white soft cheese prepared with different bacterial strains or non-inoculated cheese (control) for 28 days. The prepared cheese was pickled for four weeks at refrigerator temperature and analyzed for chemical and microbiological properties at 7, 14, 21, and 28 days. Total solids decreased over time, while protein-to-dry matter ratios increased across all treatments. Biochemically, all treated groups showed reduced serum total cholesterol, with the most significant triglyceride reduction in group V. Histopathological analysis revealed notable structural damage in testicular tissue, including degeneration of seminiferous tubules, vascular abnormalities, and a marked decrease in seminiferous tubule diameter and spermatogenic cell counts. Johnsen-like scores were significantly lower, particularly in groups III, IV, and V, indicating impaired spermatogenesis compared with the normal control. Immunohistochemically, strong Bax expression was observed in all treated groups, indicating enhanced apoptotic activity. Additionally, wide spread Plexin-B1 expression was also detected in all treated groups. These findings indicate that probiotic-enriched soft cheese may negatively affect male reproductive health, possibly through apoptosis-mediated pathways.

Anthocyanins, known for their antioxidant and anti-inflammatory properties, have been associated with cognitive benefits, potentially mediated by gut-brain axis interactions. This study investigates the effects of a 12-week Anthocyanin-Rich Extract (ARE) intervention on brain activity and gut microbiota composition in older adults with neurocognitive impairments. In this study, 50 participants underwent electroencephalography (EEG) recordings and gut microbiota analyses before and after the intervention. EEG data were analyzed using connectivity and entropy metrics across multiple frequency bands. Gut microbiota composition was assessed via 16S rRNA sequencing to evaluate taxonomic shifts. Results revealed increased EEG connectivity, particularly in alpha, beta, and gamma frequency bands, suggesting improved neural communication and complexity following ARE consumption. Significant changes in nonlinear EEG metrics were observed, consistent with previous findings in the literature. Microbiota analysis indicated non-significant alterations in overall diversity but revealed increases in Alistipes, Streptococcus thermophilus, and Flavonifractor, alongside a decrease in Hungatella, potentially implicating SCFA metabolism and inflammatory regulation. These findings suggest ARE may enhance cognitive health by modulating neural activity and gut microbiota composition. While these results provide preliminary evidence of neuroprotective effects, further research with larger, disorder-specific cohorts and placebo-controlled designs is necessary to validate outcomes and explore gut-brain axis mechanisms in cognitive decline.

Aging-related cognitive impairment, characterized by DNA damage and mitochondrial dysfunction, still lacks effective treatment strategies. Recent findings suggest that Lactobacillus delbrueckii (LD), Streptococcus thermophilus (ST) and Bifidobacterium longum (LB) may have the ability to ameliorate mitochondrial dysfunction and DNA damage. Therefore, to elucidate the antiaging effects of these probiotics, we administered LD, ST, LB, and their combinations to 4 month-old senescence-accelerated-mouse-prone 8 (SAMP8) mice for 24 weeks. Consequently, these probiotics and their combinations alleviated neuronal damage, enhanced synaptic plasticity, mitigated telomere attrition, improved mitochondrial function, and enhanced cognitive and memory functions in aging SAMP8 mice. In the gut microbiota and metabolites, the relative abundance of Limosilactobacillus, Ligilactobacillus, piperidine-4-carboxamide, and Leu-Ile-Glu-Glu increased and that of Paramuribaculum decreased in the probiotic-treated SAMP8 mice. In summary, the antiaging effects, attributed to alleviating telomere attrition and enhancing mitochondrial function, for probiotics were confirmed in aging mice, with the probiotic combinations exhibiting a larger effect.

A freeze-dried natural starter culture (NSC) was developed and assessed for its suitability in producing a semi-cooked, 60-day-ripened cheese resembling the protected designation of origin (PDO) Pecorino Sardo. The culture, derived from raw ewe’s milk from a dairy farm involved in the study, without thermal decontamination to preserve indigenous microbiota, was enriched with two strain-level-characterised, biodiverse mixtures of Streptococcus thermophilus (Str-mix) and Lactobacillus delbrueckii (Lb-mix). This study evaluated the technological robustness and adaptability of NSC enriched with biodiverse Str-mix and Lb-mix across three different artisanal dairy-processing environments with varying milk compositions and equipment levels at plants located in different geographic areas. During cheesemaking, technological, physico-chemical, and compositional parameters were monitored, along with microbial characterisation of milks and 1-day cheeses. After 60 days of ripening, cheeses were characterised from the microbiological, physico-chemical, and compositional perspectives. Furthermore, nutritional labelling was established, and consumer acceptance was determined. Results showed that the starter (NSC + Str-mix + Lb-mix) demonstrated strong and reproducible technological performance in all dairies, regardless of the milk’s chemical and microbial composition variability. Sensory quality was preserved in cheeses ripened for up to 180 days. These preliminary findings seem to support the use of freeze-dried, raw-milk-derived natural cultures in artisanal cheesemaking as a way to preserve microbial diversity and to reconnect with traditional practices that enhance both the tangible and intangible assets of modern society.

The sustainable valorisation of agro-industrial by-products offers a promising pathway to address global protein demand while supporting circular food systems. This study explored the biotechnological potential of pumpkin (Cucurbita pepo), sunflower (Helianthus annuus), and walnut (Juglans regia L.) oilseed cakes as substrates for developing vegan yoghurt-like fermented beverages. Each formulation was fermented with Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and comprehensively evaluated for composition, functionality, sensory properties, and bioactivity. The oilseed-based beverages exhibited protein levels between 3.7–4.6%, fibre content up to 1.9%, and reduced syneresis (14–18%) compared with the commercial almond-based product (21.5%). The walnut-based variant (WOCY) showed the highest total polyphenol content (1108.97 mg GAE kg−1) and antioxidant activity (412.54 mg Trolox kg−1 DPPH; 51.5 mg TE g−1 DW ABTS), surpassing both the almond-based vegan yoghurt (238.82 mg GAE kg−1) and dairy reference (96.10 mg GAE kg−1). Preliminary sensory profiling through the Check-All-That-Apply (CATA) method indicated that pumpkin- and walnut-based samples were most associated with “creamy texture,” “nutty aroma,” and “very pleasant” descriptors, achieving acceptance comparable to or higher than conventional yoghurts. Microbiological analyses confirmed product safety and high viable cell counts (<108 CFU mL−1) after 14 days of storage. Oilseed cakes serve as efficient substrates for producing nutrient-dense, antioxidant-rich, and sensorially appealing plant-based fermented beverages, supporting functional food innovation and promoting circular bioeconomy through the sustainable valorisation of agro-industrial by-products.

BackgroundCodY (Control of dppY) is a global transcriptional regulator of Streptococcus thermophilus (ST). In this study, we utilized a S. thermophilus codY gene deletion mutant strain to explore metabolites that may affect the oxidative-stress resistance of Lactobacillus delbrueckii subsp. bulgaricus. The context of this research is to understand the role of CodY in the interaction between S. thermophilus and L. delbrueckii, particularly focusing on the impact of CodY on the oxidative-stress resistance of L. delbrueckii.ResultsFirstly, the ST-1ΔcodY mutant strain was constructed by the knockout technique. We found that codY gene deletion significantly reduced the growth rate and resistance to oxidative stress of L. delbrueckii in co-culture, with a decrease in viable bacterial count to 5.26 ± 0.04 log(cfu/mL), and a decrease in survival by 15% and 25% under 5 mM and 10 mM H2O2 stress, respectively. Metabolites were comprehensively analyzed under three different culture conditions, and we identified 35 differentiated metabolites associated with CodY regulation. These metabolites were screened by their significant differential metabolite expression folds (up- or down-regulation) under different culture conditions, and Variable Importance in Projection (VIP) values assessed their significance, fold changes, and P values. Further, we identified six compounds, including lysine, 4-hydroxyphenylacetic acid, cycloleucine, glycine-L-lysine, 3-hydroxyphenylacetic acid, and N6-acetyl-L-lysine, which significantly enhanced the oxidative-stress resistance of L. delbrueckii. The viable counts of L. delbrueckii were increased by 7.73%, 6.49%, 4.27%, 3.62%, 2.12%, and 1.38%, respectively, in the medium supplemented with these substances under the stress of 10 mM H2O2.ConclusionsThe study results are important for understanding the synergistic effect of the two bacteria during fermentation and their response to environmental stresses. The findings provide insights into the role of CodY in modulating the oxidative-stress resistance of L. delbrueckii and highlight the potential of identified metabolites to enhance the performance of this bacterium under stress conditions. This could have implications for the development of strategies to improve the robustness of industrial fermentation processes involving these bacteria.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12866-025-04478-3.

Microorganisms need suitable conditions (temperature, pH and environment) specific to each microorganism in order to survive. It is also known that different microorganisms in the same environment compete for life with each other. In terms of health benefits, it is generally desired that probiotic bacteria maintain their viability for a longer period of time. For this purpose, prebiotics (inulin, trihalose, skim milk powder, whey protein isolate (WPI), ectoin, etc.) or inactive bacterial cells (parabiotics) are added to the medium of probiotic bacteria to maintain the viability of microorganisms. In this study, we investigated whether non-viable bacterial cells can be used as medium or prebiotic by Streptococcus thermophilus ATCC 14485 and probiotic Lactiplantibacillus plantarum 5102 bacteria. In our study, 2.5% WPI was used as a positive control. S. thermophilus and Burckholderia sp. bacteria are parabiotic and their prebiotic usability by S. thermophilus and probiotic L. plantarum bacteria was tested. As a result, S. thermophilus was able to utilize both its own and Burckholderia sp. non-viable cells as a prebiotic, while L. plantarum was only partially able to utilize S. thermophilus non-viable cells as a prebiotic.

Streptococcus thermophilus alleviates fatty liver disease by regulating gut microbiota, lipid metabolism, and inflammation.

Small black soybeans (Seomoktae, SBS), traditionally regarded as medicinal beans in East Asia, contain abundant bioactive compounds with antioxidant and anti-inflammatory potential. This study aimed to develop a functional plant-based milk substitute by fermenting soymilk (yellow soybean, YS) supplemented with SBS (25% or 50%) using Streptococcus thermophilus JAMI_LB_02 and Lactiplantibacillus plantarum JAMI_LB_05 (patented LABs) to enhance probiotic functionality and nutritional value. Fermentation characteristics, microbial viability, antioxidant activity, anthocyanin content, and free amino acid profiles were evaluated. After 72 h, total acidity in all samples exceeded 0.81%, and viable LAB counts reached 10.07–10.21 log CFU/mL, surpassing the Korean Food Code. The 50% SBS formulation exhibited significantly higher radical scavenging activity, total phenol and flavonoid contents, and anthocyanin levels (p < 0.05). Digestive enzyme treatment increased total free amino acid in SBS 50%, particularly functional amino acids such as arginine, alanine, and asparagine. Heatmap analysis classified products with high SBS content as Group A and analyzed the correlation between redness, antioxidant activity, and water-soluble amino acid content. Overall, SBS-fermented soymilk is an improved protein digestibility, probiotic-rich, and alternative to dairy-based fermented products, aligning with the growing consumer demand for plant-based functional foods.

The aims of this research were to evaluate the ability of three strains of lactic acid bacteria as starter culture for jack bean milk fermentation and to study their chemical and functional properties. Fermentations were carried out at 37 ℃ for 24 h for each strain of Lactobacillus plantarum WGK 4, Streptococcus thermophilus Dad 11, and Lactobacillus plantarum Dad 13. Cell growth, titratable acidity (TA), pH, β-glucosidase activity, and total phenolic content (TPC) were monitored every six hours. Quantification of isoflavones was determined using Ultra Fast Liquid Chromatography (UFLC). The antioxidant properties were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The result showed that all three LAB strains grew well in jack bean milk to 9.15-9.26 log CFU/ml, produced acid, and decreased the pH from 6.54 to 4.71-5.00 after 24 h fermentation. During fermentation, all three LAB strains could produce β-glucosidase (27.08-27.18 mU/ml) and released aglycones content in jack bean milk (3.71- 4.02 µg/g daidzein and 9.00-10.26 µg/g genistein). TPC and DPPH radical scavenging activity increased 1.1-1.4 fold and 1.4 fold (30-42%), respectively. The results indicate all three LAB strains have a similar ability to increase antioxidant properties and potentially be good starter cultures for jack bean milk fermentation.