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The present study was designed to investigate the effects of dietary non-encapsulated and microencapsulated Lactobacillus delbrueckii subsp. bulgaricus on growth performance, intestinal enzymatic activities, antioxidant capacity and hepato-biochemical parameters of rainbow trout before or after exposure to lead via diet. Fingerling fish (16 ± 4 g) were divided into four groups: negative control (NC), positive control (PC), probiotic (PR) and encapsulated probiotic (EN-PR). During the pre-exposure period (days 0–45), fish in the NC and PC groups received the basal diet, whereas fish in the PR and EN-PR groups were fed with basal diet containing 108 CFU g−1 feed of non-encapsulated and microencapsulated probiotic, respectively. During the exposure period (days 46–66), the fish in the probiotic and PC groups were co-treated with 500 μg g−1 feed of lead nitrate. Blood, liver and gut samples were taken at days 0, 45, 52, 59 and 66. The results revealed that growth performance and intestinal enzymatic activities were significantly (PL. delbrueckii subsp. bulgaricus, particularly in the microencapsulated form, can be used as a potential probiotic to protect rainbow trout from dietborne lead toxicity.

Several Lactobacillus ssp. are recognized as potential conjugated linoleic acid (CLA) producers. We have previously reported the ability of a range of Lactobacillus delbrueckii subsp. bulgaricus strains to produce CLA in fermented milk, being a potential candidate for the fermented dairy food chain. This study reports the draft genome sequence of L. bulgaricus strain LBP UFSC 2230, isolated from Italian Grana Padano cheese. Draft genome sequence originated in a total of 4,310,842 paired-end reads that were quality trimmed and assembled into 135 contigs with a total length of 604,745,873 bp, including 2086 protein coding genes and an average GC content of 49.7%. Draft genome sequence represents an important tool to identify the enzymes involved in this strain's CLA metabolism. We identified a gene encoding an enzyme involved in biohydrogenation of linoleic acid pathway, oleate hydratase.

Nanoemulsion delivery systems are thermodynamically stable and are efficient in encapsulating the bioactive compounds, and thereby improve bioavailability of bioactive compounds. Probiotics are encapsulated in nanoemulsion to enhance their viability during storage until consumption. In the present study, an oil in water nanoemulsions were formulated with differing concentration of components by high energy method. The aqueous phase consists of soy protein isolate (SPI), gum Arabica (GA), tween 80 and oil phase consist of sunflower oil. From the result it was concluded that, emulsion stabilized by soy protein isolate in the presence of 1% tween 80 and 2% gum Arabic has good emulsifying capacity. The droplet size was

During the storage of yogurt, acid-resistant bacteria continue to produce lactic acid (i.e., post-acidification process), leading to undesirable taste and flavor. Many methods have been proposed to inhibit post-acidification. However, the specific genes involved during this biological process have not yet been systematically studied. Hence, herein, we assessed the culture starter Lactobacillus delbrueckii subsp. bulgaricus ATCC11842 with regards to its transcriptomes under in vitro acid- and cold-culture conditions. Through differential gene expression analysis, we screened out 69 candidate genes that persistently responded to acid with or without cold stress. qPCR was then used to determine the in situ expression levels of these candidate genes at different stages of yogurt fermentation and storage. Genes whose expression levels did not change much from the end of fermentation to the early stage of yogurt storage were more likely to be post-acidification genes, as such stability indicated that they were not affected by cold stress. LDB_RS05285 was determined to be one such gene; the overexpression of this gene showed that the increase of gene expression could reduce the acid production of the strain without affecting normal growth. Therefore, the genetic manipulation techniques that increased the expression level of the LDB_RS05285 gene might have the potential to inhibit the post-acidification of yogurt. Thus, LDB_RS05285 plays an important role in the post-acidification process and would become a new target for regulating yogurt post-acidification.

Kishk is a fermented cereal product made traditionally from bourghul (cracked wheat) and yogurt. Being a fermented product, which gets stored and used over a period of a year, moisture and acidity are two critical components of the preparation method and storage/spoilage. We investigated the effect of a pure Lactic acid bacteria (LAB) starter culture (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus) on the acidity and consumer acceptability of Lebanese Kishk. Traditional Lebanese Kishk was prepared and used as a control in this study. Three additional test samples were prepared by adding the following to bourghul; fresh cow milk “Milk”, milk and LAB “Milk+LAB”, and yogurt prepared by inoculating fresh cow milk with LAB. Samples containing yogurt exhibited higher acidity and lower moisture content during the preparation and fermentation phase, both of which are required parameters for safety. Even though the final product of all samples were comparable to the control in terms of moisture, the “Milk+LAB” sample was more acidic than the control. None of the tested samples had a significant impact on consumer overall acceptability of the final product; however, the “Yogurt+LAB” sample was significantly preferred over the control for its odor.

To produce nattokinase in a food-grade expression system and evaluate its thrombolytic activity in vitro. No nattokinase activity from reconstituted strains was observed in simulated gastric juice, but the enzyme was stable in intestinal fluid, the relative activity of which was found to be 60% after 4 h. Due to the nattokinase being produced intracellularly by recombinant bacterial strains, the persistence of the bacteria in gastric juice ensured transmission of the nattokinase into intestinal juice. Because of subsequent disintegration of the bacteria, the highest nattokinase activity was observed after 3 h at approximately 32%, following its carriage within the recombinant strains to the intestinal fluid. This study demonstrated that nattokinase from recombinant strains exhibited good thrombolytic activity in vitro and may be used by the dairy fermentation industry for the development of novel thrombolytic functional foods.

The rice is the main food crop worldwide. The fungi Pyriculariaoryzae infected the rice and caused a decrease in rice production. The silver nanoparticle (AgNPs) are popular in several research areas such as cosmetics, agriculture, and medicine due to their biological activities and environmentally friendly. Interestingly, the biosynthesis using the microbe is a preferred alternative route for AgNPs production because it does not involve a supplementary reducing agent. The objective of this work was to biosynthesize the AgNPs using Lactobacillus delbrueckii subsp. bulgaricus and then also evaluate for antifungal activity against P.oryzae. Biosynthesis of AgNPs was used Lactobacillus delbrueckii subsp. bulgaricus cultured with AgNO3 in Man, Rogosa, and Sharpe medium. AgNPs characterized using UV-Vis spectrophotometer and particle size analyzer (PSA). The AgNPs sample at different concentrations (0.1%, 0.25%, 0.5%, 10%, 25%, 50%, 75%, and 100%) were evaluated for antifungal properties against P. oryzae using the agar diffusion method. Results confirmed the absorbance maximum of AgNPs at 423 nm. The size of the AgNPs was 2.0 nm. AgNPs showed antifungal activity against P. oryzae and the highest activity was observed at 0.75% concentration.The results showed the AgNPs could be used as a complementary to bio-fungicide against P. oryzae in the blast disease treatment of rice.

The aim of this research was to determine the optimal medium for Exopolysaccharides (EPS) production by a Lactobacillus delbrueckii subsp. bulgaricus ropy strain isolated from a locally produced commercial fermented milk, in reconstituted skim milk (RSM) 10% (w/v), milk whey (MW), and soy milk whey (SMW), under optimal growth conditions for this strain. Milk whey was made by coagulating fresh milk using papaya latex 3% (v/v); soy milk whey was obtained from tofu household industry. The chemical composition of the substrate media was determined by proximate analysis, and sterilization was accomplished in an autoclave at 121°C for 15 min. Culture media were inoculated with 1% (v/v) of a starter culture of L. delbrueckii subsp. bulgaricus and then incubated at 30°C for 16 hr. EPS production, lactic acid content, cell counting, and pH were determined after the media were cooled at 5°C. Findings showed that on the basis of the growth characteristics of L. delbrueckii subsp. bulgaricus, the best medium for EPS production was RSM 10% (258.60 ± 26.86 mg/L) compared to the milk whey (69.60 ± 9.48 mg/L) and soy milk whey (49.80 ± 9.04 mg/L).

Gioddu is the sole variety of fermented milk originating in Italy. Despite the long history of consumption, Gioddu still represents an undisclosed source of microbial diversity. The present study was aimed to get an insight into the bacterial and fungal diversity of Gioddu samples collected from two artisan producers located in Sardinia. To this end 3 batches of Gioddu were collected from each producer and subjected to Polymerase Chain Reaction–Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analyses. Gioddu was produced with sheep milk in accordance with the local tradition. Regarding the bacterial population, a low biodiversity emerged. In more detail, the sole species Lactobacillus delbrueckii subsp. bulgaricus was detected in all the samples, irrespective of the producer or the batch. A more ample microbial diversity was highlighted for the fungal population that included closest relatives to Pichia cactophila, Kluyveromyces marxianus and Galactomyces candidum. Based on the results, the detected bacterial and fungal species generally clustered in accordance with the producer, irrespective of the batch considered. It is noteworthy that, Gioddu revealed several microbiological similarities with kefir beverage, thus suggesting, by analogy, potential health benefits related to its consumption. More research is needed to better clarify the microbiota composition of Gioddu by using more powerful metagenomic techniques.

Lactobacillus delbrueckii subsp. bulgaricus CH9‐3 proteinase is an enzyme that plays an important role in yogurt fermentation, by which its use is linked to gel properties of yogurt. In this work, a modified glucono‐δ‐lactone (GDL) acidification model was used to simulate the fermentation of yogurt and study the effect of CH9‐3 proteinase on GDL‐acidified milk gel. The results showed that the proteinase significantly improved the quality of milk gel by increasing its firmness, consistency, and viscosity index, while decreasing its syneresis. Furthermore, the proteinase could accelerate the formation of milk gel as indicated by the decrease in surface charge of milk gel. The findings demonstrate that CH9‐3 proteinase has a positive effect on the properties of milk gel, and thus may have promising applications in the yogurt making industry.

Exopolysaccharides production by 3 ropy strains of Lactobacillus delbrueckii subsp. bulgaricus of dairy origin was evaluated in synthetic medium by combining different approaches: impedometric measurements, fluorescent microscopy and flow cytometry analyses. The evaluation of ΔE by impedometric measurement (E%max-E%40h) allowed the detection of EPS production in synthetic medium, but the differences in EPS production kinetic was highlighted by flow cytometry analysis and fluorescent microcopy. This approach enabled us to unravel the diversity in EPS synthesis and release into the laboratory medium during the growth of the strains. Our results showed that the maximum EPS production occurred after 8 h of incubation, when cells were in late exponential growth phase. Furthermore, flow cytometry analysis revealed that only part of the cell population could be identified as EPS producer or as EPS-bounded cell. Therefore, the combined approach used, allowed us to define at the same time the kinetics of EPS production and release by three strains belonging to the same species and, highlight that the production of EPS depends also on the number of EPS-producing cells within the same population. This approach could be useful for the selection of strains to be used as starter cultures in dairy products where EPS production is considered an important feature.

This research investigated the antimicrobial activity and antibiotic susceptibilities of nine Lactobacillus delbrueckii subsp. bulgaricus strains and nine Streptococcus thermophilus strains isolated from commercial yoghurt cultures. The antimicrobial activities of overnight culture strains against Bacillus cereus CECT 131, Bacillus subtilis ATCC 6633, Campylobacter jejuni NCTC 11351, Candida albicans ATCC 14053, Enterobacter aerogenes ATCC 13048, Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 7644, Pseudomonas aeruginosa ATCC 9027, Salmonella typhimurium ATCC 14028 and Staphylococcus aureus ATCC 12600 were investigated using the disc diffusion method. The antibiotic resistance/susceptibility profiles of the strains were determined using antibiotic discs, which included ampicillin (10µg), ampicillin (25µg), bacitracin (10µg), clindamycin (2µg), clindamycin (10µg), erythromycin (10µg), erythromycin (15µg), gentamicin (10µg), gentamicin (120µg), nalidixic acid (30µ), neomycin (10µg), novobiocin (5µg), oxacillin (1µg), penicillin (10units), streptomycin (25µg), streptomycin (300µg), tetracycline (30µg) and vancomycin (30µg). The results of the study showed that while the Streptococcus thermophilus strain SY8, Lactobacillus bulgaricus strains LY6, LY8, LY9 and LY10 showed antimicrobial activity for all test microorganisms, Streptococcus thermophilus SY5 strains showed the weakest antimicrobial effect. All the Lactobacillus bulgaricus and Streptococcus thermophilus strains were resistant to oxacillin (1?g) and nalidixic acid (30?g). Indeed, the highest antibiotic susceptibility was seen with antibiotics such as ampicillin (25?g), clindamycin (10?g) and erythromycin (15?g). © 2021, Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA. All rights reserved.

Dehydration of lactic acid bacteria for technological purposes conducts to multilevel damage of bacterial cells. The goal of this work was to determine at which molecular level fructose-oligosaccharides (FOS) and sucrose protect Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333 during the vacuum-drying process. To achieve this aim, the cultivability and metabolic activity of vacuum-dried bacteria were firstly determined (plate counting and absorbance kinetics). Then, the membrane integrity and fluidity were assessed using propidium iodide and Laurdan probes (general polarization -GP-), respectively. Finally, bacterial structural alterations were determined using high throughput methods (fluorescence confocal microscopy and Raman spectroscopy coupled to Multivariate Curve Resolution analysis -MCR-). The vacuum-drying process directly affected the microorganism's cultivability and membrane integrity. Non-dehydrated cells and sugar protected bacteria (both with FOS or sucrose) presented high GP values typical from the gel state, as well as phospholipids microdomains laterally organized along the cytoplasmic membrane. On the contrary, bacteria dehydrated without protectants presented low GP values and greater water penetration, associated with membrane destabilization. Raman spectroscopy of vacuum-dried cells revealed DNA conformational changes, B-DNA conformations being associated to non-dehydrated or sugar protected bacteria, and A-DNA conformations being higher in bacteria vacuum-dried without protectants. These results support the role of FOS and sucrose as protective compounds, not only acting at the membrane organizational level but also preventing conformational alterations of intracellular structures, like DNA.

Here, we report the ndraft genome sequences of Lactobacillus delbrueckii subsp. bulgaricus strains CBC-LB69 and CBC-LB8. The strains were isolated from naturally processed, homemade dairy foods in Bulgaria. The two genome assemblies each resulted in 39 contigs, with total lengths of 1,752,493 and 1,759,908 bp and GC contents of 49.80% and 49.90%, respectively., Here, we report the draft genome sequences of Lactobacillus delbrueckii subsp. bulgaricus strains CBC-LB69 and CBC-LB8. The strains were isolated from naturally processed, homemade dairy foods in Bulgaria. The two genome assemblies each resulted in 39 contigs with total lengths of 1,752,493 and 1,759,908 bp and GC contents of 49.80% and 49.90%, respectively.

Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) is a microaerophylic anaerobe, which is widely used in the production of yogurt, cheese, and other fermented dairy products. L. bulgaricus and its partner Streptococcus thermophilus were used as starter cultures of yogurt in the world for thousands of years. In our previous study, L. bulgaricus LDB-C1 was obtained from traditional fermented milk, and possessed some characteristics like high exopolysaccharide yield and good fermentation performance. The analysis of its CRISPR-Cas system, antibiotic resistance, virulence factors, and mobile elements, was performed to reveal the stability of the strain LDB-C1. It was found that LDB-C1 contains a plenty of spacers in the CRISPR region, indicating it might have better performance against the infection of phages and plasmids. Furthermore, the acquired or transmittable antibiotic resistance/virulence factor genes were absent in the tested L. bulgaricus strain LDB-C1.

The aim of this work was to investigate the effect of pulsed electric fields (PEF) on the growth and acidification kinetics of Lactobacillus delbrueckii subsp. bulgaricus CFL1 during fermentation. The PEF treatments were applied during the fermentation process using a recirculation pump and a PEF treatment chamber coupled with a PEF generator. The medium flow rate through the chamber was first optimized to obtain the same growth and acidification kinetics than the control fermentation without medium recirculation. Different PEF intensities (60&ndash, 428 V cm&minus, 1) were then applied to the culture medium to study the impact of PEF on the cells&rsquo, behavior. The growth and acidification kinetics were recorded during the fermentation and the specific growth rates &micro, pH, and acidification rate (dpH/dt) were assessed. The results obtained showed a biphasic growth by applying high PEF intensities (beyond 285 V cm&minus, 1) with the presence of two maximal specific growth rates and a decrease in the acidification activities. It was demonstrated that the cells were stressed during the PEF treatment, but presented an accelerated growth after stopping it, leading thereby to similar absorbance and pH at the end of the fermentation. These results show the great potential of PEF technology to be applied to generate low acidified products by performing PEF-assisted fermentations.

Cashew apple is not practically used such as cashew nut which is one of most traded agricultural export products from Northern Ivory Coast. This work focus on the use of cashew apple juice as food additive in production of yoghurt. The aim of this study is to evaluate physicochemical parameters of cashew apple juice and its effect on fermentative activity of two lactic bacteria (Lactobacillus delbrueckii subsp bulgaricus and Streptococcus salivarius subsp thermophilus). Various types of yoghurt were formulated with incorporation of different proportions (0%, 5%, 10%, 15%, 25%, 35% and 40%) of cashew apple juice in milk (v/v). Each formulation was fermented with lactic ferment containing the above two lactic bacteria. Effect of juice on fermentative activity of the two bacteria was carried out by pH, titratable acidity with duration of fermentation to obtain 80 Dornic degrees. Results of phytochemical analysis (p

&lsquo, Red Globe&rsquo, table grapes are large, edible, seeded fruit with firm flesh that tastes good, but can have poor postharvest shelf-life. This study was conducted to explore the effects of products of Lactobacillus delbrueckii subsp. bulgaricus strain F17 and Leuconostoc lactis strain H52 on &lsquo, table grapes for the enhancement of shelf-life and improvement of grape quality characteristics during postharvest storage. Strains F17 and H52 were isolated from traditional fermented yak milk obtained in the Qinghai&ndash, Tibetan Plateau. Samples from untreated and treated grapes were analyzed for physicochemical, biochemical, and microbiological properties (weight loss, decay rate, pH, total soluble solids content, titratable acidity, total phenols, sensory evaluation, and microbial growth) for 20 days. The results demonstrated that supernatants from both strains significantly reduced weight loss, decay rate, aerobic mesophilic bacteria, and coliform bacteria counts, delayed maturity and senescence of table grapes, and reduced titratable acidity and total phenols. However, the supernatant of strain F17 was more effective and resulted in better sensory evaluations and had a significant inhibitory effect on yeast and molds by day 5. Meanwhile, the supernatant from strain H52 had a significant inhibitory effect on fungi over the whole storage period. In addition, the results of the Pearson correlation analysis suggested that weight loss, decay rate, total soluble solids content, and microorganisms were highly correlated with the sensory evaluation data and quality of postharvest grapes when treated with the products of strain F17. On the basis of these data and sensory organoleptic qualities, the supernatant containing products from strain F17 had the best potential as a biopreservative to improve the postharvest quality of &lsquo, table grapes.

Glycine betaine (GB) is a naturally occurring osmolyte that helps cells adapt to osmotic stress. In this study, the osmoprotective role of GB in Lactobacillus delbrueckii subsp. bulgaricus 34.5 under salt stress was investigated. A concentration of 0.2 m NaCl provided sufficient osmotic constraint while allowing the cells to survive. Under conditions of salt stress, Lactobacillus bulgaricus 34.5 continued to proliferate in the presence of GB, and the optimum growth was seen at 1.2 m m GB. The optimum culture conditions for L. bulgaricus 34.5 were 37 °C and pH 6.0 for 24 h. In addition, intracellular GB content increased in response to salt stress, and the extent of GB transport in L. bulgaricus 34.5 under high salt concentrations depended on the culture conditions. In conclusion, GB played a protective role in alleviating the detrimental effect of salt on L. bulgaricus 34.5.

The gut is an extremely complicated ecosystem where micro-organisms, nutrients and host cells interact vigorously. Although the function of the intestine and its barrier system weakens with age, some probiotics can potentially prevent age-related intestinal dysfunction. Lactobacillus delbrueckii subsp. bulgaricus 2038 and Streptococcus thermophilus 1131, which are the constituents of LB81 yogurt, are representative probiotics. However, it is unclear whether their long-term intake has a beneficial influence on systemic function. Here, we examined the gut microbiome, fecal metabolites and gene expression profiles of various organs in mice. Although age-related alterations were apparent in them, long-term LB81 yogurt intake led to an increased Bacteroidetes to Firmicutes ratio and elevated abundance of the bacterial family S24-7 (Bacteroidetes), which is known to be associated with butyrate and propanoate production. According to our fecal metabolite analysis to detect enrichment, long-term LB81 yogurt intake altered the intestinal metabolic pathways associated with propanoate and butanoate in the mice. Gene ontology analysis also revealed that long-term LB81 yogurt intake influenced many physiological functions related to the defense response. The profiles of various genes associated with antimicrobial peptides-, tight junctions-, adherens junctions- and mucus-associated intestinal barrier functions were also drastically altered in the LB81 yogurt-fed mice. Thus, long-term intake of LB81 yogurt has the potential to maintain systemic homeostasis, such as the gut barrier function, by controlling the intestinal microbiome and its metabolites.

The first objective of this work included the development of real-time polymerase chain reaction (RT-PCR) which is also known as quantitative polymerase chain reaction (qPCR) assays to quantify two species of lactic acid bacteria which play a very important role in cheese ripening: Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. The second objective was the comparison of qPCR and plate counts of these two species present in raw cow’s milk cheese samples during different stages of ripening. Thirty-three deoxyribonucleic acid (DNA) samples coming from seven different bacterial species, which were phylogenetically related or commonly isolated from raw milk and dairy products, were chosen as positive and negative controls. The qPCR assays showed a high quantification capacity characterised by their linearity (R2 > 0.998), PCR efficiencies which were within the range 78.0–90.0% for L. delbrueckii subsp. bulgaricus, and 93.6–100.5% for S. thermophilus, and quantification limit (103 gene copies/ml for L. delbrueckii subsp. bulgaricus and 10 gene copies/ml for S. thermophilus). The importance of our study is in the monitoring of changes in populations of L. delbrueckii subsp. bulgaricus and S. thermophilus contributing to cheese ripening using the newly designed qPCR assay.

Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333 was encapsulated by layer-by-layer (LbL) technique. Copolymers of pluronic and poly(acrylic acid), were synthesized and characterized, and chitosan was selected as cationic polyelectrolyte. The efficiency of encapsulation was evaluated by plate counting the microorganisms before and after coating, after freeze-drying with sucrose, and after exposure to simulated gastrointestinal conditions. Coated microorganisms with 2/3 layers were also protected against simulated gastro-intestinal conditions, while cultivability of uncoated bacteria significantly dropped. Confocal microscopy allowed determining the integrity and permeability of the coated and uncoated microorganisms. Coated bacteria were non-toxic to eukaryotic cells, by the MTT assay, and showed no significant decrease of cultivability before and after freeze-drying and after 60 days of storage at 4 °C. Considering the GRAS status of the used polymers, the results obtained revealed a potential delivery system of sensitive lactic acid bacteria strains in food products, ensuring their safe arrival to the gut. Fil: Quintana, Gabriel Sebastian. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Simões, M.G.. Universidad de Coimbra; Portugal Fil: Hugo, Ayelen Amelia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Alves, P.. Universidad de Coimbra; Portugal Fil: Ferreira, P.. Universidad de Coimbra; Portugal Fil: Gerbino, Oscar Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Simões, P.N.. Universidad de Coimbra; Portugal Fil: Gomez Zavaglia, Andrea. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina

Understanding the effect of pH on the growth of Lactobacillus delbrueckii subsp. Bulgaricus is essential for controlling starters production. Previous studies suggested that L. bulgaricus Q7 in uncontrolled pH cultures showed better acidic activity in milk compared with that in controlled pH cultures. The present study aimed to elucidate the effect of uncontrolled and controlled pH cultures on the growth of L. bulgaricus Q7. The growth kinetics, physiological state, amino acid consumption and necessary profiles of L. bulgaricus Q7 were investigated in the complete chemically defined medium under uncontrolled and controlled pH cultures circumstances respectively. The results showed that the average growth rate and final biomass of L. bulgaricus Q7 were higher in uncontrolled pH cultures than those in controlled pH cultures. Furthermore, the high intracellular pH led to the high average growth rate and final biomass in uncontrolled pH cultures. The H+-ATPase activity, ATP concentration, ratio of NADH/NAD+, NH3 concentration, consumption and necessary profiles of amino acid led to high intracellular pH in uncontrolled pH cultures. Such results might benefit industrial starter producers and fermented-product manufacturers by allowing them to formulate new strategies to enhance biomass of L. bulgaricus and better control the quality of starters.

Galactooligosaccharides (GOS) are useful dietary ingredients recognized worldwide as prebiotics. In the present study, we evaluated the β-galactosidase (β-gal) activity of a panel of lactic acid bacteria (LAB) in order to select strains for the synthesis of oligosaccharides from lactose (GOS) and lactulose (OsLu) with a potential prebiotic effect. Fifteen strains out of 20 were able to grow on lactose and showed β-gal activities between 0.03 and 2.06 U mg−1, whereas eleven were able to synthesize GOS. Lactobacillus delbrueckii subsp. bulgaricus CRL450, the strain with the highest β-gal activity, synthesized a maximum of 41.3% GOS and 21.0% OsLu from lactose and lactulose, respectively, with β-(1 → 6) and secondary β-(1 → 3) linkages. When these compounds were tested without purifying, as carbon sources for the development of recognized probiotics and the producer strain, high growth was observed compared to non-prebiotic sugars like glucose and lactose. When the purified oligosaccharides were tested, the bacterial growth decreased, but the microorganisms displayed metabolic activity evidenced by the consumption of carbohydrates and the production of lactic acid. Additionally, the purified oligosaccharides demonstrated a bifidogenic effect. The obtained results support the potential of L. delbrueckii subsp. bulgaricus CRL450 for the production of the prebiotics GOS and OsLu and encourage the optimization of their synthesis for the design of new functional food ingredients., This work was supported by PICT 2014-3583 from ANPCyT (Agencia Nacional de Promoción Científica y Tecnológica, Argentina), IC-603 and IC-801 from USPT (Universidad de San Pablo-Tucumán), Project I-COOP_2014_COOPB20099 and EMHE-CSIC 2017 MHE-200047 from CSIC (Consejo Superior de Investigaciones Científicas, España); and AGL2017-84614-C2-1-R from MICINN.

Strawberries are vulnerable to physical injuries and microbial invasion. To explore if beneficial lactic acid bacteria can improve the shelf life and edible quality of postharvest strawberry fruits, the effects of Lactobacillus delbrueckii subsp. bulgaricus (ital.) F17 (F17) and Leuconostoc lactis (ital.) H52 (H52) inoculation on the strawberry microbial community structure and saleable characteristics were examined by bacterial 16S rRNA and fungal ITS sequencing techniques. Lactobacillus (ital.) F17 and Leuconostoc lactis (ital.) H52 isolated from the traditional fermented yak milk in the Qinghai-Tibetan Plateau were used as the potential probiotic inocula. Samples from treated strawberries stored at 25 °C for 0, 12, 24, 48, and 72 hours were analyzed for their pH, weight loss percentage, decay percentage, total soluble solid content (SSC) and microbial counts, and for microbiome community diversity and canonical correspondence analysis. The results showed that F17 and H52 did not only significantly reduce the weight loss and decay percentage of strawberry fruits, but also delayed the decrease of the total SSC and pH (P < 0.05). In addition, F17 and H52 significantly inhibited the growth and colonization of aerobic mesophilic bacteria, yeast, mold and coliform bacteria. In particular, by comparing the microbiota composition of the samples, F17 significantly inhibited Pantoea, Mycospherella, unclassified_Pleosporales, Aureobasidium and Phoma at the genus level, whereas H52 inhibited Bacillus, Streptophyta, Mycospherella, Aureobasidium and Phoma. Moreover, analysis of alpha and beta diversity revealed that F17 and H52 had a significantly greater inhibitory effect on bacterial species compared to fungi. The results of canonical correspondence analysis revealed that the total SSC and pH were positively correlated with bacteria, whereas the decay percentage, weight loss percentage and total SSC were positively associated with fungi. Additionally, Podosphaera, Hanseniaspora, Botrytis and unclassified_Pleosporales were positively correlated with strawberry fruit decay and weight loss percentage. As a general result, Lactobacillus F17 and Leuconostoc lactis H52 have the potential to promote biological preservation, which is economically important to reduce the loss due to strawberry spoilage.

Lactobacillus delbrueckii subsp. bulgaricus is one of the predominant lactic acid bacterial species used as starter cultures in industrial fermented dairy manufacturing, as it strongly affects the quality of the products. Volatile flavor compound profiles and fermentation characteristics are considered to be the most important indicators for starter culture screening. In the present study, volatile compounds in milk fermented by 17 test strains of L. delbrueckii subsp. bulgaricus and a commercial strain used as a control were identified using solid-phase microextraction (SPME) methods coupled with gas chromatography mass spectrometry (GC-MS). In total, 86 volatile flavor compounds were identified in the fermented milk upon completion of fermentation, including 17 carboxylic acids, 14 aldehydes, 13 ketones, 29 alcohols, 8 esters, and 5 aromatic hydrocarbon compounds. Various volatile flavor compounds (acetaldehyde, 3-methyl-butanal, (E)-2-pentenal, hexanal, (E)-2-octenal, nonanal, 2,3-butanedione, acetoin, 2-heptanone, 2-non-anone, formic acid ethenyl ester) were identified due to their higher odor activity values (>1). In addition, of the 17 test strains of L. delbrueckii subsp. bulgaricus, IMAU20312 (B14) and IMAU62081 (B16) strains exhibited good fermentation characteristics in milk compared with the control strain. The combination of the volatile flavor compound profile and fermentation characteristics in this work could be useful when selecting lactic acid bacteria that may serve as important resources in the development of novel fermented milk products.

Processed meats are classified by the International Agency for Research on Cancer (IARC) as carcinogenic to humans. However, information on the responsible agents and the influence of industrial processing on the increased risk of cancer is still lacking. This study aimed to use cultures of Lactobacillus delbrueckii subsp. bulgaricus LB-UFSC 01 to biodegrade harmful C-nitrous, N-nitro, and C-nitro compounds in processed meat matrix. Firstly, positive results for ethylnitrolic acid (ENA) (>5.00 μg kg−1) and 2-methyl-1,4-dinitro-pyrrole (DNMP) (>12.0 μg kg−1) were obtained in mortadellas produced under different experimental conditions employing preservatives and antioxidants. Mortadellas containing nitrite and sorbate in the ratio of 8:1 (w/w) yielded the highest concentrations of mutagens. However, the treatment with the LB-UFSC 01 culture was able to modulate the harmful compounds in the mortadella samples. Several analytical methods employing liquid chromatography coupled to mass spectrometry and statistical models were employed to identify the metabolites and reaction routes during microbial biotransformation. For the first time, relevant information regarding the formation and degradation of ENA and DNMP in a processed meat model simulating real conditions was presented.

Infectious disease-causing pathogens can be transmitted via contact with contaminated environmental surfaces (i.e., fomite transmission). However, the physical mechanism of fomite transmission remains unclear because of a lack of suitable surrogate tracers. In this study, the non-toxic, non-human-origin and gram-positive bacterium Lactobacillus delbrueckii subsp. Bulgaricus was selected as a tracer, and its applicability for studying bacterial contamination spread on environmental surfaces was investigated in an office setting. After bacterial introduction by a designated carrier, surface contamination levels indicated by the L. bulgaricus proline iminopeptidase (pepIP) gene copy numbers were quantified using an optimized qPCR assay. This qPCR assay exhibited a high sensitivity (55 copies per reaction mixture and 1585 copies per surface sample), a wide dynamic range (7 orders of magnitude) and a high specificity for pepIP gene in environmental surface samples. Three independent, natural and unsupervised field experiments involving human participants confirmed the applicability of L. bulgaricus as a tracer in field studies and the pepIP gene as a unique marker of externally introduced contamination. Experimentally, contamination was distributed nearly equally over public surfaces, the carrier's seat location and the other seat locations in the office setting. An analysis by seat location revealed that the contamination level was attenuated as the physical distance from the carrier's seat location increased. Volunteers' faces were ubiquitously contaminated, suggesting a potentially high risk of fomite exposure via mucous membranes. In conclusion, L. bulgaricus can feasibly be used as a tracer organism in future large-scale field studies of bacterial contamination spread on environmental surfaces.

Streptococcus thermophilus SDMCC18 contains a novel bi-functional glutathione synthetase gene gshF, and it can produce glutathione (GSH). In the present study, we demonstrated that the produced GSH by S. thermophilus SDMCC18 could protect cells against acid challenge and be secreted into the medium. Moreover, using a gshF-defective mutant strain as the control, we found that the GSH conferred a protective role against acid stress to Lactobacillus delbrueckii subsp. bulgaricus ATCC11842. In addition, L. bulgaricus ATCC11842 could import the exogenous GSH into the cytoplasm, leading to an improved growth of strain ATCC11842. Taken together, our study reported a novel proto-cooperation relationship between S. thermophilus and L. bulgaricus in yoghurt fermentation. (C) 2016 Elsevier Ltd. All rights reserved.

Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus are used in the fermentation of milk to produce yoghurt. These species normally metabolize only the glucose moiety of lactose, secreting galactose and producing lactic acid as the main metabolic end product. We used multiple serial selection steps to isolate spontaneous mutants of industrial strains of S. thermophilus and L. delbrueckii subsp. bulgaricus that secreted glucose rather than galactose when utilizing lactose as a carbon source. Sequencing revealed that the S. thermophilus strains had mutations in the galKTEM promoter, the glucokinase gene, and genes encoding elements of the glucose/mannose phosphotransferase system (PTS). These strains metabolize galactose but are unable to phosphorylate glucose internally or via the PTS. The L. delbrueckii subsp. bulgaricus mutants had mutations in genes of the glucose/mannose PTS and in the pyruvate kinase gene. These strains cannot grow on exogenous glucose but are proficient at metabolizing internal glucose released from lactose by β-galactosidase. The resulting strains can be combined to ferment milk, producing yoghurt with no detectable lactose, moderate levels of galactose, and high levels of glucose. Since glucose tastes considerably sweeter than either lactose or galactose, the sweetness of the yoghurt is perceptibly enhanced. These strains were produced without the use of recombinant DNA technology and can be used for the industrial production of yoghurt with enhanced intrinsic sweetness and low residual levels of lactose. IMPORTANCE Based on a good understanding of the physiology of the lactic acid bacteria Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus , we were able, by selecting spontaneously occurring mutants, to change dramatically the metabolic products secreted into the growth medium. These mutants consume substantially more of the lactose, metabolize some of the galactose, and secrete the remaining galactose and most of the glucose back into the milk. This allows production of yoghurt with very low lactose levels and enhanced natural sweetness, because humans perceive glucose as sweeter than either lactose or galactose.

The rheological and physical characteristics of non-fat set yogurt produced using co-cultures of ropy EPS-producing Streptococcus thermophilus S3.3 and Lactobacillus delbrueckii subsp. bulgaricus LTM and of Streptococcus thermophilus S3.3 and Lactobacillus delbrueckii subsp. bulgaricus H+-ATPase-defective mutant L6 under different conditions were studied. Yogurts produced with mutant L6 had a higher pH and water-holding capacity and better textural properties compared to those produced with the LTM strain. The highest storage modulus (G′) and thixotropic loops were found for yogurt made with L6 at 42°C on day 21 of cold storage. This yogurt contained a network of thick, continuous protein aggregates and large void spaces.

Peptides are important bioactive components in fermented milk, and they are released from dairy proteins by lactic acid bacteria (LAB). This study determined relationships between peptide profiles and LAB during fermentation. Streptococcus thermophilus (S. thermophilus) and Lactobacillus delbrueckii subsp. bulgaricus (Lb. bulgaricus) fermented milk separately and together. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) peptidomic approach was used to profile peptides after 0, 4, and 8 h of fermentation. Most peptides (91.2% of 181 peptides) produced by the 4 h Lb. bulgaricus fermentation had increased in intensity at 8 h, which indicated that prolonging Lb. bulgaricus fermentation was useful for peptide accumulation. The peptide structures were investigated by evaluating the probability of each amino acid in positions P1 and P1’ of peptides accumulating in fermentation. The peptides in fermentations by Lb. bulgaricus primarily had Glu (E) at P1, and those in fermentations by S. thermophilus favored Lys (K) and Val (V) at P1’. In mixed fermentation, Lb. bulgaricus, with stronger proteolytic activity, determined the peptide structure. Twenty-three bioactive peptides were identified, and 5 of them were quantified absolutely. The YQEPVLGPVRGPFPIIV peptide was most abundant in the sample fermented by Lb. bulgaricus for 8 h (19.61 μg/1000 mL). The specificity and proteolytic activity were the key factors determining the structure and concentration of peptides accumulating in milk fermentation. This study revealed the actual situation of milk fermentation, which could provide more practical information for better production of fermented milk.

Lactic acid bioconversion processes have numerous advantages over the chemical synthesis route, not only due to the high-titer yield of the final product with great optical purity, but also due to the possibility of utilizing lignocellulosic biomass feedstocks as carbon source in an economic and environmentally friendly way. In the present study, beechwood and pine were pretreated with a novel mild oxidative organosolv process to produce cellulose-rich solid fractions, which were tested for their ability to support the growth and high lactic acid productivity of Lactobacillus delbrueckii subsp. bulgaricus (ATCC® 11842). We employed a simultaneous saccharification and fermentation (SSF) strategy in batch cultures with 9% w v−1 solids loading. The results for beechwood showed the highest production of 62 g L−1 lactic acid after 72 h of incubation, corresponding to a yield of 0.69 g g−1 of biomass (82.7% of the theoretical maximum yield) and a productivity of 0.86 g L−1 h−1. In the case of pine, the productivity was lower at 0.51 g L−1 h−1, leading to accumulation of 36.4 g L−1 lactic acid, corresponding to a yield of 0.40 g g−1 of biomass (41.4% of the theoretical maximum yield). Our study suggests that L. delbrueckii subsp. bulgaricus is an efficient lactic acid bacterial strain for the production of optically pure d -lactic acid from non-edible, organosolv pretreated hardwood and softwood biomass for the synthesis of bio-based plastics and other products.

Cows’ milk allergy, common in young infants, is often solved by the age of five; however, it can persist in some adults. The in vivo immunomodulatory potential of β-lactoglobulin (BLG) hydrolysates obtained with Lactobacillus delbrueckii subsp. bulgaricus CRL656 (H656) was studied. Sera from mice gavaged with H656 showed lower specific BLG-IgE values than those of allergic mice. Secretion of IL-10, INF-γ and IL-6 was increased and that of IL-4 decreased when allergic spleen cells were stimulated with H656. IL-4 secretion was significantly reduced and concentrations of IL-10, IL-17A and IL-6 were increased when H656 was orally administrated. Highest expression of IL-4 and IL-12 was observed for allergic mice and H656 gavaged mice, respectively. H656 immunisation had a positive effect on intestinal mucosa. Overall, H656 displayed an immunomodulating effect, balancing the allergic Th2 response by stimulating Th1 type cytokine secretion. The hydrolysate might promote oral tolerance towards BLG in infant foods. Fil: Pescuma, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Hebert, Elvira Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Font, Graciela Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Saavedra, Maria Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina Fil: Mozzi, Fernanda Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina

Increased consumption of yogurt, kefir, and other fermented foods has been driven, in part, by the health benefits these products may confer. Epidemiological studies have shown that the consumption of fermented foods is associated with reduced risks of type 2 diabetes, metabolic syndrome, and heart disease, along with improved weight management. The microorganisms present in these foods are suggested to contribute to these health benefits. Among these are the yogurt starter culture organisms Streptococcus thermophilus and Lactobacillus delbrueckii subsp bulgaricus as well as Bifidobacterium and Lactobacillus strains that are added for their probiotic properties. In contrast, for other fermented foods, such as sauerkraut, kimchi, and miso, fermentation is initiated by autochthonous microbes present in the raw material. In both cases, for these fermentation-associated microbes to influence the gut microbiome and contribute to host health, they must overcome, at least transiently, colonization resistance and other host defense factors. Culture and culture-independent methods have now clearly established that many of these microbes present in fermented dairy and nondairy foods do reach the gastrointestinal tract. Several studies have shown that consumption of yogurt and other fermented foods may improve intestinal and extraintestinal health and might be useful in improving lactose malabsorption, treating infectious diarrhea, reducing the duration and incidence of respiratory infections, and enhancing immune and anti-inflammatory responses.

Prosopis nigra, a sucrose-rich crop, was used to enzymatically synthesize fructo-oligosaccharides (FOS). The obtained products were used as stabilizing matrices during freeze-drying and storage of Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333. The centesimal composition of P. nigra flour was firstly determined. FOS were synthesized using Viscozyme L as biocatalyst. The progress of the enzymatic reaction was monitored by HPLC and compared with a reaction carried out using equivalent concentrations of pure sucrose as substrate (control). Then, P. nigra containing or not the obtained FOS (P. nigra + FOS or P. nigra) were used as matrices for freeze-drying and storage of L. delbrueckii subsp. bulgaricus CIDCA 333. P. nigra flour was rich in simple sugars (sucrose and fructose), total dietary fiber, and polyphenols. The main products of synthesis were FOS with degrees of polymerization (DP) within 3 and 5, and these results were comparable with those of the controls. DP3 was the first product obtained, attaining the maximal production after 1.29 hours of synthesis. The maximal production of total FOS (DP3 + DP4 + DP5) was achieved after 2.57 hours, indicating that larger FOS (DP4, DP5) were produced from DP3. Glucose was obtained as secondary product, but with significantly lower Vmax and Kf (maximal velocity for the production and constant for the formation) than DP3. Both P. nigra + FOS or P. nigra matrices stabilized the highly sensitive L. delbrueckii subsp. bulgaricus CIDCA 333 strain during freeze-drying and storage for up to 140 days at 4 °C, and were significantly better protectants than the controls of sucrose (p

Cryopreservation-related stresses in Lactobacillus delbrueckii SUBSP. Bulgaricus: Global and multi-scale study. 55. Annual Meeting of the Society for Cryobiology

Fatigue caused by summer heat is a typical indefinite complaint along with anorexia, loss of sleep, stress, lack of motivation and, in some cases, catching a cold. Yogurt fermented with Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1 has been shown to stimulate the immune system and reduce the risk of catching colds. Here, we conducted a randomized, double-blinded, placebo-controlled trial to investigate whether ingesting this yogurt could ameliorate summer heat fatigue in 49 healthy males (median age 40.0 &plusmn, 6.0 years, 30&ndash, 49 years) who felt fatigued every summer. Fatigue was evaluated by visual analogue scales (VAS) and the balance of sympathetic/parasympathetic nervous systems. After 12 weeks of ingestion in early autumn, the VAS fatigue scores in the yogurt group were lower than those of the placebo group. These results indicate that yogurt fermented with L. bulgaricus OLL1073R-1 can ameliorate summer heat fatigue lasting up to early autumn.

In the present work, the use of scotta as substrate for bacterial fermentation was studied with the objective of obtaining a drink from transformation of this by-product. Scotta retains most of the lactose of the milk and it is normally colonized by a natural microbiota. A treatment was devised to reduce the autochthonous microbial populations in order to reduce competition towards the inoculated bacterial strains. Nine lactic acid bacteria (LAB) were assessed for their capability to develop in scotta. They evidenced different behaviors regarding growth rate, acidification capability and nitrogen consumption. A co-inoculum of three LAB, namely aStreptococcus thermophilus, aLactobacillus delbrueckiisubsp.bulgaricusand aLb. acidophilusstrains, chosen among those giving the best performances in single-strain fermentation trials, gave abundant (close to 109cfu/ml) and balanced growth and lowered pH to 4·2, a value similar to that of yogurt. These results show that scotta may have potential as a substrate for bacterial growth for the production of a fermented drink. Further studies are needed to optimize the organoleptic aspects of the final product.

Red beans exhibit many biofunctions, including the stimulation of intestinal motility, improvement of anemia and elimination of edema. This study was conducted to evaluate the functional properties of microbially fermented red beans produced under different fermentation conditions and to establish the optimum fermentation conditions for the production of fermented red beans with multiple biofunctions. The optimum fermentation conditions were the fermentation of red beans by a co-culture of Bacillus subtilis and Lactobacillus bulgaricus in the presence of 1% glucose, incubated at 30 °C for 120 h and stirred every 24 h. Compared with unfermented red beans, red beans fermented under the optimum conditions contained a higher concentration of antioxidant substances, including total phenolics, anthocyanin, flavonoids and vitamins C and E. The results of tests for DPPH-radical scavenging, ferrous ion chelation and reducing power implied a high antioxidant content. Fermented red beans exhibited nattokinase activity and contained a significant amount of potential probiotics.

Lactobacillus delbrueckii subsp. bulgaricus is an acid-tolerant species used in yoghurt production and considered important in postacidification reductions in palatability of yoghurt during storage. In this study, a variant (ND06-2) of L. delbrueckii subsp. bulgaricus ND06 was selected using neomycin sulphate. ND06-2 exhibited sensitivity to acids and lower H+-ATPase activity compared with ND06. High-pressure liquid chromatography (HPLC) was used to demonstrate that the capacity of ND06-2 to produce lactic acid was significantly lower than for ND06 during fermentation or storage. These results suggest that the L. delbrueckii subsp. bulgaricus variant could be used in yoghurt starters and have a lower tendency to cause postacidification.

The aim of this study was to investigate the proliferation effect of fractionated lotus seed resistant starch (LRS3-20%, LRS3-30%) and the structural changes following fermentation. Fractionated lotus seed resistant starch, especially LRS3-20%, promoted the proliferation of these probiotics, and Bifidobacterium longum produced large quantities of acetic acid, while Lactobacillus delbrueckii subsp. bulgaricus produced lactic acid. Additionally, the probiotics with lotus seed resistant starch (LRS3) and LRS3-20% survived more successfully in simulated gastrointestinal solutions compared to glucose, LRS3-30% and high amylose maize starch, but LRS3 and LRS3-20% differed in their abilities to enhance the tolerance to acidic buffer, bile acid and simulated gastric juice. Furthermore, after fermentation, fractionated lotus seed resistant starch displayed a loose, rough surface. The crystalline and double helical structure increased as the amount of amorphous and sub-crystalline structure reduced following fermentation. Interestingly, structural changes were correlated with the original structures and utilisation by the probiotics.

Ham fındıktan Lactobacillus delbrueckii subsp. bulgaricus ve Streptococcus thermophilus ticari suşları kullanılarak sağlığıteşvik edici, fonksiyonel özellikte fermente bir ürün elde edilmiştir. İlkaşamada, ultrasonikasyon uygulaması ile fındık sütünün homojenizasyonusağlanmıştır. Elde edilen fermente ürününün pH, titre edilebilir asitlik, serumayrılma kapasitesi, protein içeriği, yağ içeriği ve kül içeriği sırasıyla 4.95,1.25 g laktik asit/100mL, %28.00, %2.60, %7.03 ve %0.66 olarak bulunmuştur.Reolojik analizlerden elde edilen veriler fermente fındık sütünün Newtonianolmayan psödoplastik akış davranışı sergilediğini ve yapısının viskozdan dahaelastik olduğunu göstermiştir. Duyusal analiz, renk, aroma, tipik yoğurt kokusuve genel kabul edilebilirlik gibi fermente fındık sütünün bazı niteliklerininAyran’dan daha az takdir edildiğini, ancak diğer bazı özelliklerin tatmin ediciolduğu sonucuna varılmıştır., Raw hazelnut milk were used todevelop new plant-based fermented product using commercial starter mixcontaining Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains in order to address the currentdemand for health promoting and functional plant-based dairy-like products. ThepH, titratable acidity (TA), serum separation (SS), protein content, fatcontent and ash content of fermented product were found to be 4.95, 1.25 glactic acid/ 100 mL, 28.00%, 2.60%, 7.03% and 0.66%, respectively. Fermentedhazelnut milk demonstrated non-Newtonian pseudoplastic flow behavior and it’sstructure was more predominantly elastic than viscous. Sensory analysis showedthat some attributes of fermented hazelnut milk such as color, aroma,consistency, typical yoghurt odor and overall acceptability were lessappreciated than Ayran (commercial cow milk yogurt drink) whereas some otherattributes were found as satisfying.

The sterilization conditions between experiment and dairy industrial level are different and concern about influence on product’s qualities. In this study, the fermentation properties of Streptococcus thermophilus, alone and in combination with Lactobacillus delbrueckii subsp. bulgaricus, were evaluated in skim milk that had been subjected to distinct sterilization conditions. Growth, organic acid generation, and EPS production were determined using pasteurized or autoclaved milk. When S. thermophilus was cultivated in pasteurized skim milk, the growth was strain-dependent. On the other hand, growth of S. thermophilus was accelerated in autoclaved milk. Exocellular polysaccharide (EPS) production by L. bulgaricus was not affected by the combination of S. thermophilus strains. Thus, we observed that yogurt fermented by L. bulgaricus was minimally affected by the combination of S. thermophilus strains; growth of L. bulgaricus was maintained under the constant environment. These results should facilitate the development of fermented milk produced from L. bulgaricus in the dairy industry.

Background The efficacy of Lactobacillus delbrueckii subsp. bulgaricus as starter cultures for the dairy industry depends largely on the number of viable and active cells. Freeze-drying is the most convenient and successful method to preserve the bacterial cells. However, not all strains survived during freeze-drying. Methods The effects of six substances including NaCl, sorbitol, mannitol, mannose, sodium glutamate, betaine added to the MRS medium on the growth and freeze-drying survival rate and viable counts of Lb. delbrueckii subsp. bulgaricus were studied through a single-factor test and Plackett-Burman design. Subsequently, the optimum freeze-drying conditions of Lb. delbrueckii subsp. bulgaricus were determined. Results Lb. delbrueckii subsp. bulgaricus survival rates were up to the maximum of 42.7%, 45.4%, 23.6%, while the concentrations of NaCl, sorbitol, sodium glutamate were 0.6%, 0.15%, 0.09%, respectively. In the optimum concentration, the viable counts in broth is 6.1, 6.9, 5.13 (t108 CFU/mL), respectively; the viable counts in freeze-drying power are 3.09, 5.2, 2.7 (t1010 CFU/g), respectively. Conclusions Three antifreeze factors including NaCl, sorbitol, sodium glutamate have a positive effect on the growth and freeze-drying of Lb. delbrueckii subsp. bulgaricus. The results are beneficial for developing Lb. delbrueckii subsp. bulgaricus.

Lactobacillus delbrueckii subsp. bulgaricus is widely used in the production of yogurt and cheese. In this study, we present the complete genome sequence of L. delbrueckii subsp. bulgaricus ACA-DC 87 isolated from traditional Greek yogurt. Whole-genome analysis may reveal desirable technological traits of the strain for dairy fermentations.

Lead (Pb) is a toxic contaminating heavy metal that can cause a variety of hazardous effects to both humans and animals. In the present study, Lactobacillus delbrueckii subsp. bulgaricus KLDS1.0207 (L. bulgaricus KLDS1.0207), which has a remarkable Pb binding capacity and Pb tolerance, was selected for further study. It was observed that the thermodynamic and kinetic model of L. bulgaricus KLDS1.0207 Pb binding respectively fit with the Langmuir–Freundlich model and the pseudo second-order kinetic model. Scanning electron microscopy and energy dispersive spectroscopy analysis disclosed that the cell surfaces were covered with Pb and that carbon and oxygen elements were chiefly involved in Pb binding. Combined with Fourier transform infrared spectroscopy analysis, it was revealed that the carboxyl, phosphoryl, hydroxyl, amino and amide groups were the main functional groups involved in the Pb adsorption. The protective effects of L. bulgaricus KLDS1.0207 against acute Pb toxicity in mice was evaluated by prevention and therapy groups, the results in vivo showed that L. bulgaricus KLDS1.0207 treatment could reduce mortality rates, effectively increase Pb levels in the feces, alleviate tissue Pb enrichment, improve the antioxidant index in the liver and kidney, and relieve renal pathological damage. Our findings show that L. bulgaricus KLDS1.0207 can be used as a potential probiotic against acute Pb toxicity.