Streptococcus Thermophilus Research Articles

Bioactivity of Microencapsulated Cell-Free Supernatant of Streptococcus thermophilus in Combination with Thyme Extract on Food-Related Bacteria.

The bioactive properties of the combination of microencapsulated cell-free supernatant (CFS) from Streptococcus thermophilus and thyme extract on food-related bacteria (Photobacterium damselae, Proteus mirabilis, Vibrio vulnificus, Staphylococcus aureus ATCC29213, Enterococcus faecalis ATCC29212, and Salmonella Paratyphi A NCTC13) were investigated. The microencapsulated CFS of S. thermophilus, in combination with ethanolic thyme extract, had a particle size in the range of 1.11 to 11.39 µm. The microencapsulated CFS of S. thermophilus had a wrinkled, spherical form. In the supernatant, especially at 2% (v/w), the thyme extract additive caused a decrease in the wrinkled form and a completely spherical structure. A total of 11 compounds were determined in the cell-free supernatant of S. thermophilus, and acetic acid (39.64%) and methyl-d3 1-dideuterio-2-propenyl ether (10.87%) were the main components. Thyme extract contained seven components, the main component being carvacrol at 67.96% and 1,2,3-propanetriol at 25.77%. Significant differences (p < 0.05) were observed in the inhibition zones of the extracts on bacteria. The inhibitory effect of thyme extract on bacteria varied between 25.00 (P. damselae) and 41.67 mm (V. vulnificus). Less antibacterial activity was shown by the microencapsulated CFS from S. thermophilus compared to their pure form. (p < 0.05). As a result, it was found that microencapsulated forms of CFS from S. thermophilus, especially those prepared in combination with 2% (v/w) thyme extract, generally showed higher bioactive effects on bacteria.

Bacteriocin production by lactic acid bacteria using ice cream co-product as the fermentation substrate

Ice cream manufacture commonly results in the accumulation of wasted product that contains valuable food-grade quality components, including fat, carbohydrates, and protein. Methods have been developed for recovering the fat from this waste stream, but this results in the generation of a co-product rich in fermentable carbohydrates. This study aimed to investigate the potential for using this co-product as a fermentation substrate for production of antimicrobial peptides, called bacteriocins, by dairy starter cultures. Results showed that Streptococcus thermophilus B59671 and Lactococcus lactis 11454 produced the broad-spectrum bacteriocins thermophilin 110 and nisin, respectively, when the fermentation substrate was melted ice cream, or a co-product generated by a modified butter churning technique. Bacteriocin production varied depending on the brand and variety of vanilla ice cream used in this study. When an alternate enzyme-assisted fat extraction technique was used, S. thermophilus metabolism was impaired within the resulting co-product, and thermophilin 110 production was not observed. Lactococcus lactis was still able to grow in this co-product, but antimicrobial activity was not observed. Results from this study suggest the co-product generated when using the churning technique is a better choice to use as a base medium for future studies to optimize bacteriocin production.

Peculiarities of development and metabolism of &lt;i&gt;Streptococcus thermophilus&lt;/i&gt; strains under different conditions of deep liquid phase cultivation

The microflora of most fermented dairy products, including cheeses, consists entirely of lactic acid bacteria, i. e., bacterial starter cultures with different species and strain composition that are specially introduced into the mixture. The species composition of the starter must ensure the intensity and direction of the microbiological and biochemical processes of the produced product and guarantee its safety, quality and storability. In particular, lactic acid bacteria transform the main components of milk (protein, milk fat, lactose) into taste, aromatic, and biologically active substances involved in the formation of identification and organoleptic characteristics of fermented dairy products. The number of starter microorganisms in fermented dairy products, including cheeses, significantly exceeds the content of any foreign microflora and can cause the appearance of organoleptic defects such as acid, bitterness, non-specific off-taste or excessive gas formation. The ability of microorganisms to form certain metabolic products is determined both by their species and strain properties, and by cultivation conditions. These include, first of all, the composition of the development environment and temperature conditions of cultivation. By combining the composition of the starter and selecting favorable modes for cultivating microorganisms, it is possible to achieve optimal development of the starter microflora, obtaining products with the desired quality characteristics. This article presents the results of a comparative assessment of the properties of production strains of Streptococcus thermophilus during their development in dairy environments at optimal temperatures (41 ± 1) °C, simulating conditions for the production of fermented milk products, as well as in modes simulating cheese ripening conditions (11 ± 1) °C and 4% table salt concentration. The nature of the enzymatic processes of glycolysis, proteolysis, lipolysis, and flavor formation as a result of the metabolism of these cultures was also assessed.

Development of a mouse model expressing a bifunctional glutathione-synthesizing enzyme to study glutathione limitation in vivo

Glutathione (GSH) is a highly abundant tripeptide thiol that performs diverse protective and biosynthetic functions in cells. While changes in GSH availability are associated with inborn errors of metabolism, cancer and neurodegenerative disorders, studying the limiting role of GSH in physiology and disease has been challenging due to its tight regulation. To address this, we generated cell and mouse models that express a bifunctional glutathione-synthesizing enzyme from Streptococcus thermophilus (GshF), which possesses both glutamate-cysteine ligase and glutathione synthase activities. GshF expression allows efficient production of GSH in the cytosol and mitochondria and prevents cell death in response to GSH depletion, but not ferroptosis induction, indicating that GSH is not a limiting factor under lipid peroxidation. CRISPR screens using engineered enzymes further revealed genes required for cell proliferation under cellular and mitochondrial GSH depletion. Among these, we identified the glutamate-cysteine ligase modifier subunit, Gclm, as a requirement for cellular sensitivity to buthionine sulfoximne, a glutathione synthesis inhibitor. Finally, GshF expression in mice is embryonically lethal but sustains postnatal viability when restricted to adulthood. Overall, our work identifies a conditional mouse model to investigate the limiting role of GSH in physiology and disease.

High-energy ultrasound improves culture activity, polyunsaturated fatty acids and in-vitro protein digestibility in probiotic yogurt

The effect of ultrasound (US) on viable, bacteria counts, free fatty acid and amino acid content and in vitro protein digestibility of set-type probiotic yogurts produced with fortification of milk proteins (caseinate and whey protein concentrate) or skimmed milk powder (SMP) was investigated. US application increased the protein content of probiotic yogurts and enhanced the growth of yogurt bacteria, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and the probiotic bacterium, Bifidobacterium animalis subsp. lactis (BB-12), in yogurt samples. All US-treated groups had higher probiotic counts between 8.44 and 8.61 log cfu/g than their counterpart controls at the end of storage. One- or two- stage US application reduced the saturated fatty acids (SFA) ratio by up to 19% and increased the polyunsaturated fatty acids (PUFA) ratio of probiotic yogurts by up to 40%. At the beginning and end of storage, one-stage US applied Y2 and YP2 groups had the highest PUFA ratio as 36.86, 33.25 and 25.10, 20.03%, respectively, but it did not affect the monounsaturated fatty acids (MUFA) ratio. It also positively affected the in vitro protein digestibility, and total amino acid amounts of probiotic yogurts in pre- and post-digestion. The soluble protein ratios of all US-treated samples were higher both at the beginning and end of storage. Industrial relevanceUltrasound is a promising approach in dairy technology. The results obtained in this study can help to improve the probiotic viability, antioxidant capacity, PUFA content, and digestibility of proteins in dairy products by US treatment and provide an opportunity for US-treated dairy products in the functional food market. Ultrasound is a so- called green technology because it is environmentally friendly, and the use of ultrasound in production will positively affect consumer preferences. In addition, obtained data may be beneficial for the industrial use of this technology.

Daily yogurt consumption does not affect bone turnover markers in men and postmenopausal women of Caribbean Latino descent: a randomized controlled trial

BackgroundCaribbean Latino adults are at high risk for osteoporosis yet remain underrepresented in bone research. This increased risk is attributed to genetics, diet, and lifestyle known to drive inflammation and microbial dysbiosis.ObjectiveThe primary objective of this study was to determine whether consuming 5 oz of yogurt daily for 8wks improves bone turnover markers (BTMs) among Caribbean Latino adults > 50 years; and secondarily to determine the impact on the gut microbiota and markers of intestinal integrity and inflammation.MethodsFollowing a 4wk baseline period, participants were randomized to an 8wk whole fat yogurt intervention (n = 10) daily, containing only Streptococcus thermophilus and Lactobacillus bulgaricus, or to an untreated control group that did not consume yogurt (n = 10). Blood and stool samples collected at week-0 and week-8 were used to assess BTMs, inflammation, intestinal integrity biomarkers, and gut microbiota composition, short chain fatty acids (SCFAs), respectively. Data were evaluated for normality and statistical analyses were performed.ResultsParticipants were 55% women, with a mean age of 70 ± 9 years, BMI 30 ± 6 kg/m2, and serum C-reactive protein 4.8 ± 3.6 mg/L, indicating chronic low-grade inflammation. Following 8wks of yogurt intake, absolute change in BTMs did not differ significantly between groups (P = 0.06–0.78). Secondarily, absolute change in markers of inflammation, intestinal integrity, and fecal SCFAs did not differ significantly between groups (P range 0.13–1.00). Yogurt intake for 8wks was significantly associated with microbial compositional changes of rare taxa (P = 0.048); however, no significant alpha diversity changes were observed.ConclusionsIn this study, daily yogurt did not improve BTMs, inflammation, intestinal integrity, nor SCFAs. However, yogurt did influence beta diversity, or the abundance of rare taxa within the gut microbiota of the yogurt group, compared to controls. Additional research to identify dietary approaches to reduce osteoporosis risk among Caribbean Latino adults is needed.Trial registrationThis study is registered to ClinicalTrials.gov, NCT05350579 (28/04/2022).

Advancements in Biological Strategies for Controlling Harmful Algal Blooms (HABs)

Harmful algal blooms (HABs) are a primary environmental concern, threatening freshwater ecosystems and public health and causing economic damages in the billions of dollars annually. These blooms, predominantly driven by phytoplankton species like cyanobacteria, thrive in nutrient-rich, warm, and low-wind environments. Because of the adverse impacts of HABs, this review examines various control methods, focusing on biological strategies as sustainable solutions. While effective in disrupting algal populations, traditional chemical and physical interventions carry ecological risks and can be resource-intensive. Biological control methods, including biomanipulation and using algicidal microorganisms such as Streptococcus thermophiles, Myxobacteria, and Lopharia spadicea, emerge as eco-friendly alternatives offering long-term benefits. Additionally, barley and rice straw application has demonstrated efficacy in curbing HAB growth. These biological approaches work by inhibiting algal proliferation, disrupting cellular structures, and fostering algal cell aggregation. Despite their advantages over conventional methods, biological controls face challenges, including intricate ecological interactions. This article delves into the latest biological techniques aimed at eradicating HABs, intending to diminish their frequency and reduce toxin levels in aquatic environments. While most research to date has been confined to laboratory settings, scaling these methods to field applications presents hurdles due to the variability and complexity of natural ecosystems. The review underscores the need for further research and development in this critical area of environmental science.

The quorum sensing peptide BlpC regulates the transcription of genes outside its associated gene cluster and impacts the growth of Streptococcus thermophilus.

Bacteriocin production in Streptococcus thermophilus is regulated by cell density-dependent signaling molecules, including BlpC, which regulates transcription from within the bacteriocin-like peptide (blp) gene cluster. In some strains, such as S. thermophilus ST106, this signaling system does not function properly, and BlpC must be supplied exogenously to induce bacteriocin production. In other strains, such as S. thermophilus B59671, bacteriocin (thermophilin 110 in strain B59671) production occurs naturally. Here, transcriptomic analyses were used to compare global gene expression within ST106 in the presence or absence of synthetic BlpC and within B59671 to determine if BlpC regulates the expression of genes outside the blp cluster. Real-time semi-quantitative PCR was used to find genes differentially expressed in the absence of chromosomal blpC in the B59671 background. Growth curve experiments and bacteriocin activity assays were performed with knockout mutants and BlpC supplementation to identify effects on growth and bacteriocin production. In addition to the genes involved in bacteriocin production, BlpC affected the expression of several transcription regulators outside the blp gene cluster, including a putative YtrA-subfamily transcriptional repressor. In strain B59671, BlpC not only regulated the expression of thermophilin 110 but also suppressed the production of another bacteriocin, thermophilin 13, and induced the same YtrA-subfamily transcriptional repressor identified in ST106. Additionally, it was shown that the broad-spectrum antimicrobial activity associated with strain B59671 was due to the production of thermophilin 110, while thermophilin 13 appears to be a redundant system for suppressing intraspecies growth. BlpC production or induction negatively affected the growth of strains B59671 and ST106, revealing selective pressure to not produce bacteriocins that may explain bacteriocin production phenotype differences between S. thermophilus strains. This study identifies additional genes regulated by BlpC and assists in defining conditions to optimize the production of bacteriocins for applications in agriculture or human and animal health.

Gut production of GABA by a probiotic formula: an in vitro study.

The objective of this study was to evaluate the influence of a probiotic formula on the production of neuroactive compounds in different parts of the colon in batch culture and in vitro gut simulator experiments. Thirteen lactic acid bacterial strains, belonging to the species Levilactobacillus brevis, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Ligilactobacillus salivarius, Streptococcus thermophilus, were characterised for their in vitro ability to produce neurotransmitters. L. brevis P30021 and L. plantarum P30025 were selected based on their capability to produce γ-aminobutyric acid (GABA) and acetylcholine in vitro. A probiotic formulation with potential psychobiotic activity was prepared and tested in a batch culture of human microbiota monitoring the formation of GABA and acetylcholine. Samples of the three colonic tracts were taken from the Simulator of the Human Intestinal Microbiota (SHIME®) evaluating the production of GABA and other neurotransmitters by LC-MS. Short chain fatty acids (SCFA) by GC and microbiota composition by 16S rRNA gene sequencing were also determined. Probiotic supplementation led to the formation of GABA and acetylcholine with a decrease in glutamate concentrations in the in vitro batch fermentation. Production of GABA after the treatment with probiotics was confirmed in the SHIME® short-term experiment. No differences in short-chain fatty acids were observed up to 72h of fermentation. Different microbiota composition was found in the three different parts of the colon, with a higher abundance of Veillonellaceae in the ascending colon vessels. The probiotic-exposed microbiota showed higher levels of Bacteroides, a gut microbe associated with anti-inflammatory activities and a potential GABA producer. Results demonstrate the impact of the tested probiotic formula on gut microbiota structure and GABA production. In conclusion, the probiotic treatment changed the microbiota composition and increased neuroactive metabolites production, indicating promising potential as psychobiotics, even if further clinical evidence is needed to confirm the effectiveness of these probiotics in improving mental health.

Digestive characteristics of extracellular polysaccharide from Lactiplantibacillus plantarum T1 and its regulation of intestinal microbiota

This study assessed the potential prebiotic characteristics of the previously reported Lactiplantibacillus plantarum extracellular polysaccharide (EPS-T1) with immunological activity. EPS-T1 was a novel heteropolysaccharide composed of glucose and galactose (1.00:1.21), with a molecular weight of 1.41 × 106 Da. The monosaccharide composition, molecular weight, fourier transform infrared, and 1H NMR analysis showed that EPS-T1 was well tolerated in the simulated oral cavity, gastric fluid, and small intestinal fluid environments, and was not easily degraded. Meanwhile, EPS-T1 could effectively be used as a carbon source to promote the growth of beneficial Lactobacillus species (Lactobacillus delbrueckii ssp. Bulgaricus, Streptococcus thermophilus, Lacticaseibacillus rhamnose GG, Lactiplantibacillus plantarum, Lacticaseibacillus paracasei and Lactobacillus reuteri). After 24 h of fecal fermentation, EPS-T1(5 mg/mL) effectively reduced the relative abundance of harmful bacteria such as the Escherichia-Shigella, Citrobacter, Fusobacterium, Parasutterella, and Lachnoclostridium. While, the level content of beneficial flora (Bacteroides, Blautia, Phascolarctobacterium, Bifidobacterium, Parabacteroides, and Subdoligranulum) were significantly increased. In addition, EPS-T1 was able to significantly promote the enrichment of short-chain fatty acids such as acetic acid, propionic acid and butyric acid. These results provide some basis for the functional application of EPS-T1 as a potential prebiotic.

In vitro evaluation of the application of an optimized xylanase cocktail for improved monogastric feed digestibility.

Xylanases from glycoside hydrolase (GH) families 10 and 11 are common feed additives for broiler chicken diets due to their catalytic activity on the nonstarch polysaccharide xylan. This study investigated the potential of an optimized binary GH10 and GH11 xylanase cocktail to mitigate the antinutritional effects of xylan on the digestibility of locally sourced chicken feed. Immunofluorescence visualization of the activity of the xylanase cocktail on xylan in the yellow corn of the feed showed a substantial collapse in the morphology of cell walls. Secondly, the reduction in the viscosity of the digesta of the feed by the cocktail showed an effective degradation of the soluble fraction of xylan. Analysis of the xylan degradation products from broiler feeds by the xylanase cocktail showed that xylotriose and xylopentaose were the major xylooligosaccharides (XOS) produced. In vitro evaluation of the prebiotic potential of these XOS showed that they improved the growth of the beneficial bacteria Streptococcus thermophilus and Lactobacillus bulgaricus. The antibacterial activity of broths from XOS-supplemented probiotic cultures showed a suppressive effect on the growth of the extraintestinal infectious bacterium Klebsiella pneumoniae. Supplementing the xylanase cocktail in cereal animal feeds attenuated xylan's antinutritional effects by reducing digesta viscosity and releasing entrapped nutrients. Furthermore, the production of prebiotic XOS promoted the growth of beneficial bacteria while inhibiting the growth of pathogens. Based on these effects of the xylanase cocktail on the feed, improved growth performance and better feed conversion can potentially be achieved during poultry rearing.

Perspective of Streptococcus thermophilus Strains as New Probiotics Derived from the Breast Milk of Indian Mothers

ABSTRACT In this study, two lactic acid bacterial cultures were isolated from human milk, and their probiotic attributes were evaluated. The 16S rRNA technique confirmed that the isolates share close homology to Streptococcus thermophilus and are designated as HN2 and HN3 strains. Both cultures showed significant tolerance, i.e. 74–92% and 66–88% survivability in acidic and bile conditions, respectively (p < 0.05). The hydrophobicity values ranged from 26–39% against hydrocarbons, auto-aggregation (40–51%), and β-galactosidase activity (43–102 U/mL) were observed, while antagonistic activity against pathogens ranged between 12–26 mm. The antibiotic profile demonstrated that the HN3 strain was more resistant compared to the HN2 strain. The antioxidant activities of supernatant and intact cells were determined using DPPH and ABTS method and found between 37–89%. The safety parameters data revealed that hemolytic reaction and mucin degradation were not detected. The findings suggested that the strains could be potentially targeted in functional foods for therapeutic applications following further in vivo studies.

Development of a functional Greek sheep yogurt incorporating a probiotic Lacticaseibacillus rhamnosus wild-type strain as adjunct starter culture

Greek yogurt is a fermented dairy product of high nutritional value that can be used as a matrix for the delivery of probiotics. The aim of this study was to develop a new probiotic Greek sheep yogurt with upgraded quality and functional characteristics. To do this, yogurt was manufactured by fermenting pasteurized milk with the commercial starter culture (Streptococcus thermophilus (ST), Lactobacillus bulgaricus (LB)) together with a probiotic Lacticaseibacillus rhamnosus (LR) wild-type strain (probiotic yogurt; PY). As a control, yogurt manufactured with only the starter culture (ST, LB) was used (conventional yogurt; CY) The survival of all three lactic acid bacteria (LAB) species (ST, LB, and LR) was monitored throughout the products’ shelf life (storage at 4 °C for 25 days), and also following exposure to a static in vitro digestion model (SIVDM). The population dynamics of total aerobic plate count (APC), Enterobacteriaceae, yeasts and molds grown in both yogurts were also determined. The total antioxidant activity (AA) of yogurts was comparatively determined using in parallel two different assays, whereas the Folin-Ciocalteu assay was used to determine their total phenolic content (TPC). At each sampling day, yogurts were also evaluated for their pH, titratable acidity (TA) and main sensory characteristics. The population of probiotic LR remained stable during the shelf life (and above 108 CFU/g). Yogurt starters (ST, LB) were not detected following SIVDM, whereas LR (in PY) presented a reduction of about only one log. The AA and TPC of PY were found significantly higher than that of CY (P < 0.05). At the end of storage (25th day), neither pH nor TA differed significantly between the two yogurt types, while no fungal growth was observed in the PY. Consumer sensory analysis did not reveal important differences between the two yogurt types during their shelf life. To sum up, the novel yogurt was able to deliver to consumers a high number of probiotic cells (>108 CFU/g), presented increased antioxidant power, had an expanded shelf life, and maintained its good sensory attributes.

Addition of transglutaminase enzyme in camel milk yoghurt to increase its sensorial aspects.

Camel milk was obtained from A-block UVAS Ravi Campus Pattoki. After pasteurization at 72 °C (15 sec) it was cooled to 42 °C, then glutathione treated transglutaminase enzyme was added with the concentration of 0.5 g/300 mL, 1 g/300 mL, 1.5 g/300 mL, 2 g/300 mL while control sample with the addition of 1.5 g/300 mL gelatin. Then inoculation of milk was done with standard cultures of Yoghurt Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus at the rate of 2% for 3-4 hours at 42 °C. Samples were stored at 4 °C and were analyzed on 1st day and 28th day of storage. In our findings, there was slight increase in sensorial properties of all the samples. It was also observed that syneresis was reduced with the increase of enzyme quantity.

The effectiveness of probiotics as an adjunct therapy in patients under mechanical ventilation: an umbrella systematic review and meta-analysis.

The literature regarding the role of probiotics in critically ill patients who have undergone mechanical ventilation (MV) is unclear; therefore, this umbrella systematic review and meta-analysis was carried out to clarify the effects of probiotics on the clinical outcomes of mechanically ventilated patients. The Scopus, PubMed/Medline, ISI Web of Science, and Google Scholar online databases were searched up to February 2023. All meta-analyses evaluating the impact of probiotics in patients under MV were considered eligible. The assessment of multiple systematic reviews (AMSTAR) questionnaire was used to evaluate the quality of the studies. Data were pooled using the random-effects approach. Thirty meta-analyses and nine clinical outcomes were re-analyzed. Probiotics significantly decreased ventilator-associated pneumonia (VAP) incidence, nosocomial infections, intensive care unit (ICU) length of stay, hospital length of stay, ICU mortality, hospital mortality, MV duration, duration of antibiotic use, and diarrhea. The obtained results of the current umbrella meta-analysis indicate that probiotic administration could be considered an adjunct therapy for critically ill patients; however, no specific probiotic treatment regimen can be recommended due to the diverse probiotics used in the included meta-analyses. The following microorganisms were used at various doses and combinations throughout the studies: Lacticaseibacillus casei, Lactiplantibacillus plantarum, L. acidophilus, L. delbrueckii, L. bulgaricus, Bifidobacterium longum, B. breve, B. salivarius, Pediococcus pentosaceus, Lactococcus raffinolactis, B. infantis, B. bifidum, Streptococcus thermophilus, Ligilactobacillus salivarius, L. lactis, B. lactis, Saccharomyces boulardii, L. rhamnosus GG, L. johnsonii, L. casei, S. faecalis, Clostridium butyricum, Bacillus mesentericus, L. sporogenes, S. boulardii, L. paracasei, B. subtilis, and Enterococcus faecium.

Lacticaseibacillus casei- and Bifidobacterium breve-fermented red pitaya promotes beneficial microbial proliferation in the colon.

Red pitaya has been demonstrated to strongly inhibit α-glucosidase activity; however, the impact of red pitaya fermentation by probiotic bacteria on α-glucosidase inhibition remains unclear. In this study, six strains of lactic acid bacteria (Lactiplantibacillus plantarum, Lacticaseibacillus rhamnosus, Lactobacillus bulgaricus, Lacticaseibacillus casei, Lactobacillus acidophilus and Streptococcus thermophilus) and one strain of Bifidobacterium breve were utilized for the fermentation of red pitaya pulp. The α-glucosidase and α-amylase inhibition rates of red pitaya pulp were significantly greater after fermentation by Bifidobacterium breve and Lacticaseibacillus casei than by the other abovementioned strains. The LC group exhibited an α-glucosidase inhibition rate of 99%, with an α-amylase inhibition rate of 89.91%. In contrast, the BB group exhibited an α-glucosidase inhibition rate of 95.28%, accompanied by an α-amylase inhibition rate of 95.28%. Moreover, red pitaya pulp fermented with Bifidobacterium breve and Lacticaseibacillus casei produced a notable quantity of oligosaccharides, which was more than three times greater than that in the other groups. Furthermore, 16S rRNA high-throughput sequencing analysis was conducted to assess alterations in the composition of the gut microbiota. This revealed an increase in the abundance of Lactobacillus and Faecalibacterium in the pulp fermented by Bifidobacterium breve and Lacticaseibacillus casei, whereas the abundance of Sutterella decreased. Further analysis at the species level revealed that Bifidobacterium longum, Faecalibacterium prausnitzii, and Lactobacillus zeae were the dominant strains present during colonic fermentation. These results indicate a beneficial health trend associated with probiotic bacterial fermentation of red pitaya pulp, which is highly important for the development of functional products.

Identification of a population balance model for Streptococcus thermophilus

The identification of a cell population balance model for the fermentation of the lactic acid bacterium Streptococcus thermophilus based on experimental data is addressed. As a starting point, a mass balance model is parameterized and then cell division rates identified exploring data from cell size distribution measurements as well as microscope images. The particular problem lies in the fact that Streptococcus th. grows in chains build up during cell division in dependence on physico-chemical parameters like lactic acid concentration, while cell size distribution (CSD) measurements do not clearly distinguish between cell and chain size. It is shown that, by using a factorized function for the cell division rate that reflects these different effects and can be identified using experimental data, it is possible to obtain an adequately parameterized model that is able to predict the time evolution of the CSD, opening the path for different process monitoring and control schemes.

Study of the influence of Lacticaseibacillus paracasei AS-10 on the development of a traditional starter for Bulgarian yoghurt

A study was conducted to investigate the effect of lactic acid bacteria development involved in starter cultures for the production of lactic acid products. On the basis of the data obtained, concerning its influence on a traditional starter for Bulgarian yoghurt, it is possible to interpret its development in a symbiotic culture, its influence on the organoleptic profile of yoghurt and the rate of development of the lactic acid process. To achieve the set objective, cultivation of the selected lactic acid strains was carried out. The data on the rate of development in the different phases, represented by the acid formation curve for a symbiotic traditional culture for Bulgarian yoghurt containing Lactobacillus delbrueckit ssp bulgaricus u Streptococcus thermophilus, with Lacticaseibacillus paracasei AS-10 added to them, were reported. The conclusions drawn allow the correct and predictable use of the investigated lactic acid bacteria strain in starter cultures for the production of lactic acid products.

Tecno-funcionalidades e capacidade antioxidante de farinha de grão-de-bico fermentada por Lacticaseibacillus casei ou por co-cultura (Lactobacillus acidophilus, Bifidobacterium e Streptococcus thermophilus)

ABSTRACT: Chickpea (Cicer arietinum L.; GB) is one of the most consumed pulses worldwide. Fermentation with lactic acid bacteria (LAB) has been a strategy to improve the nutritional and technological quality of chickpea flours, in addition to reducing the levels of antinutritional factors. Thus, this study evaluated the effect of fermentation with Lacticaseibacillus casei or co-culture on water activity (Aw), color, antioxidant capacity, and techno-functional properties of chickpea flour. Chickpeas were fermented at 28 °C for 96 h with Lactobacillus Casei or co-culture, resulting in the samples GBLC and GBCC, respectively, dried at 50 °C, and ground to obtain the flours. Fermentation reduced (P &lt; 0.05) the Wa and color parameters (L*, a*, and b*) of the fermented flours (GBCC and GBLC). In terms of techno-functional properties, GBCC flours showed lower emulsifying capacity (EC, 80%) and emulsion stability (ES, 82.50%). GBLC and GBCC flours showed significant differences (P &lt; 0.05) in swelling power only at 25 °C and a reduction in water solubility index (WSI) at all studied temperatures. LAB fermentation reduced the antioxidant capacity of GBLC e GBCC flours determined by the DPPH method, while in the FRAP method, there was an increase for GBCC and a reduction for GBLC. For the total phenolic content (TPC), there was an increase of 231% for GBCC flour and 164% for GBLC flour. Thus, it was concluded that the fermentation with Lactobacillus Casei and co-culture affected the Wa, color, EC, ES, WSI, the antioxidant capacity by the DPPH and FRAP assays, and the TPC of the fermented flours.

Study of regime parameters of the process of cultivation of a consortium of probiotic microorganisms providing increased synthesis of exopolysaccharides

The paper conducted experimental studies of the activity of exopolysaccharide synthesis by a consortium of probiotic microorganisms based on Streptococcus thermophiles, Bifidobacterium bifidum, Bifidobacterium longum, Bifidobacterium adolescentis, Bifidobacterium breve, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus fermentum. Temperature conditions of cultivation were studied on the basis of combination of stages of optimal and non-optimal conditions for development of microorganisms corresponding to temperature variation in the range of higher or lower values, in order to intensify synthesis of moisture-binding metabolites of polysaccharide nature. The results of studies of optical density and concentration of biomass exopolysaccharides are given, which indicate a positive effect on the synthesis of exopolysaccharides of the used combined temperature modes of cultivation. Based on thermal analysis data, endothermic effects were identified, indicating an additional increase in the degree of moisture binding by polysaccharides of probiotic origin. It was found that the maximum activity of the synthesis of moisture-binding metabolites corresponds to the combined cultivation mode with a sequential transition from the area of low temperature effects to the optimal area.