Angiotensin-converting enzymes 1 and 2 in the feces: presence and catalytic activity in the rat 2,4,6-trinitrobenzene sulfonic acid-induced model of colitis

BACKGROUND AND AIM

Inflammatory bowel disease is challenging to diagnose. Fecal biomarkers offer noninvasive solutions. The renin-angiotensin-aldosterone system is implicated in intestinal inflammation. Angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) regulate its activity, but conflicting findings on these enzymes in colitis require further investigation. We aimed to assess ACE and ACE2 presence and activities in the feces, serum, and colon of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rats.

METHODS

Colitis was induced in male rats by rectal instillation of a 21% ethanolic TNBS solution. After rats' sacrifice, colonic portions, serum, and feces were collected. ACE and ACE2 presence in the feces was analyzed by western Blot, and colonic and serum enzymes' concentrations were quantified using ELISA kits. ACE activity was assessed using Hippuryl-His-Leu and Z-Phe-His-Leu as substrates. ACE2 activity was assessed using Mca-APK (Dnp) as a substrate in the presence and absence of DX600 (ACE2 inhibitor).

RESULTS

An ACE isoform of ~70 kDa was found only in the feces of TNBS-induced rats. ACE concentration was higher than that of ACE2 in the serum and the inflamed colon. ACE N-domain activity was higher than that of the C-domain in all matrices. ACE2 activity was higher in the feces of TNBS-induced animals compared to controls.

CONCLUSION

A 70 kDa ACE isoform only detected in the feces of TNBS-induced rats may have translational relevance. ACE N-domain seems to play a significant role in regulating colonic lesions. Further research using human samples is necessary to validate these findings.

Functional yogurt, enriched and probiotic: A focus on human health

The food industry has always sought to produce products enriched with vitamins, probiotics, polyphenols, and other bioactive compounds to improve physiological function, enhance nutritional value, and provide health. These compounds are essential for human health, and their deficiency can lead to adverse effects. Therefore, food enrichment is an important strategy to improve the nutritional value and, in some cases, improve the quality of food. Recently, functional foods have been very popular around the world. Among food products, dairy products constitute a major part of people's diet, and due to the high consumption of dairy products, including yogurt, the enrichment of this product effectively reduces or prevents diseases associated with nutritional deficiencies. Most consumers generally accept yogurt due to its high nutritional value and low price. So, it can be considered a good candidate for enrichment with micronutrients and probiotics. In recent years, using functional foods to prevent various diseases has become a popular topic for research. In this study, the effect of fortified yogurt in preventing diseases and improving deficiencies has been investigated, and it has been proven that super healthy yogurt has a positive effect on human health.

Safety aspects, probiotic potentials of yeast and lactobacillus isolated from fermented foods in North-Eastern India, and its anti-inflammatory activity

Lactobacillus and yeast obtained from fermented foods in North-East India were tested for safety and probiotic properties. All the lactobacilli and yeast tested negative for the catalase, indole, urease, phenylalanine, hemolysis, gelatin hydrolysis, and biogenic amine production tests, indicating that they are safe to use as probiotics in food supplements. Lactiplantibacillus plantarum KGL3A (accession no. MG722814) was capable of resisting the replicated gastric fluid (pH 2) till 2 h of exposure, whereas both KGL3A and Lacticaseibacillus rhamnosus K4E (accession no. KX950834.1) strains were able to resist pH 3 till 2 h of exposure with a reduction in overall viable cell count from 7.48 log CFU/mL to 1.09 log CFU/mL and 7.77 log CFU/mL to 0.83 log CFU/mL, respectively. In vitro gastric juice simulation conditions were tolerated by the yeast Saccharomyces cerevisiae WBS2A. The cell surface hydrophobicity (CSH) towards hydrocarbons (n-hexadecane) was seen highest in L. plantarum KGL3A (77.16± 0.84%) and Limosilactobacillus fermentum KGL4 accession no. MF951099 (72.60 ± 2.33%). The percentage auto-aggregation ranged from 8.70 to 25.53 after 2 h, which significantly increased to 10.50 to 26.94 during the fifth hour for cultures. Also, a higher percentage of co-aggregation was found for the culture L. rhamnosus K4E with S. typhi (34.18 ± 0.03%), E. coli (32.97 ± 0.02 %) and S. aureus (26.33 ± 0.06 %) and for the yeast S. cerevisiae WBS2A, a higher percentage of co-aggregation was found with Listeria monocytogenes (25.77 ± 0.22%). The antioxidant activity and proteolytic activity were found to be higher for Lactobacillus helveticus K14 and L. rhamnosus K4E. The proportion of decreased cholesterol was noticeably higher in KGL4 (29.65 ± 4.30%). β glucosidase activity was significantly higher in the L. fermentum KGL4 strain (0.359 ± 0.002), and α galactosidase activity was significantly higher in the L. rhamnosus K4E strain (0.415 ± 0.016). MTT assays suggested that KGL4 and WBS2A at a lower dose did not exhibit cytotoxicity.

Optimal preparation of food waste to increase its utility for sophorolipid production by Starmerella bombicola

Secondary feedstocks, such as food waste (FW), have been used for yeasts (e.g. Starmerella bombicola) to produce sophorolipids (SLs), which are commercially available biosurfactants. However, the quality of FW varies by location and season and may contains chemicals that inhibit SLs production. Therefore, it is crucial to identify such inhibitors and, if possible, remove them, to ensure efficient utilization. In this study, large scale FW was first analysed to determine the concentration of potential inhibitors. Lacticacid, acetic acid and ethanol were identified and found to be inhibitors of the growth of S. bombicola and its SLs production. Various methods were then evaluated for their ability to remove these inhibitors. Finally, a simple and effective strategy for removing inhibitors from FW was developed that complied with the 12 principles of green chemistry and could be adopted by industry for high SLs production.

Biochemical and Genomic Characterization of Two New Strains of Lacticaseibacillus paracasei Isolated from the Traditional Corn-Based Beverage of South Africa, Mahewu, and Their Comparison with Strains Isolated from Kefir Grains

Lacticaseibacillus paracasei (formerly Lactobacillus paracasei) is a nomadic lactic acid bacterium (LAB) that inhabits a wide variety of ecological niches, from fermented foodstuffs to host-associated microenvironments. Many of the isolated L. paracasei strains have been used as single-strain probiotics or as part of a symbiotic consortium within formulations. The present study contributes to the exploration of different strains of L. paracasei derived from non-conventional isolation sources-the South African traditional fermented drink mahewu (strains MA2 and MA3) and kefir grains (strains KF1 and ABK). The performed microbiological, biochemical and genomic comparative analyses of the studied strains demonstrated correlation between properties of the strains and their isolation source, which suggests the presence of at least partial strain adaptation to the isolation environments. Additionally, for the studied strains, antagonistic activities against common pathogens and against each other were observed, and the ability to release bioactive peptides with antioxidant and angiotensin I-converting enzyme inhibitory (ACE-I) properties during milk fermentation was investigated. The obtained results may be useful for a deeper understanding of the nomadic lifestyle of L. paracasei and for the development of new starter cultures and probiotic preparations based on this LAB in the future.

An update on angiotensin-converting enzyme 2 structure/functions, polymorphism, and duplicitous nature in the pathophysiology of coronavirus disease 2019: Implications for vascular and coagulation disease associated with severe acute respiratory syndrome coronavirus infection

It has been known for many years that the angiotensin-converting enzyme 2 (ACE2) is a cell surface enzyme involved in the regulation of blood pressure. More recently, it was proven that the severe acute respiratory syndrome coronavirus (SARS-CoV-2) interacts with ACE2 to enter susceptible human cells. This functional duality of ACE2 tends to explain why this molecule plays such an important role in the clinical manifestations of coronavirus disease 2019 (COVID-19). At the very start of the pandemic, a publication from our Institute (entitled "ACE2 receptor polymorphism: susceptibility to SARS-CoV-2, hypertension, multi-organ failure, and COVID-19 disease outcome"), was one of the first reviews linking COVID-19 to the duplicitous nature of ACE2. However, even given that COVID-19 pathophysiology may be driven by an imbalance in the renin-angiotensin system (RAS), we were still far from understanding the complexity of the mechanisms which are controlled by ACE2 in different cell types. To gain insight into the physiopathology of SARS-CoV-2 infection, it is essential to consider the polymorphism and expression levels of the ACE2 gene (including its alternative isoforms). Over the past 2 years, an impressive amount of new results have come to shed light on the role of ACE2 in the pathophysiology of COVID-19, requiring us to update our analysis. Genetic linkage studies have been reported that highlight a relationship between ACE2 genetic variants and the risk of developing hypertension. Currently, many research efforts are being undertaken to understand the links between ACE2 polymorphism and the severity of COVID-19. In this review, we update the state of knowledge on the polymorphism of ACE2 and its consequences on the susceptibility of individuals to SARS-CoV-2. We also discuss the link between the increase of angiotensin II levels among SARS-CoV-2-infected patients and the development of a cytokine storm associated microvascular injury and obstructive thrombo-inflammatory syndrome, which represent the primary causes of severe forms of COVID-19 and lethality. Finally, we summarize the therapeutic strategies aimed at preventing the severe forms of COVID-19 that target ACE2. Changing paradigms may help improve patients' therapy.

Purification and Characterization of Novel Antihypertensive and Antioxidative Peptides From Whey Protein Fermentate: In Vitro, In Silico, and Molecular Interactions Studies

OBJECTIVE

The goal of this research was to purify and characterize the novel angiotensin-converting enzyme (ACE)-inhibitory and antioxidant peptides from fermented whey protein concentrate produced by Lactobacillus paracasei and Saccharomyces cerevisiae in a co-fermentation system.

METHOD

Whey protein fermented with lactic acid bacteria and yeast culture was analyzed for antioxidative, ACE inhibition, as well as anti-inflammatory activity followed by SDS-PAGE, isoelectric focusing, and 2-dimensional (2D) analysis. Anti-inflammatory activity of whey protein fermentate was also studied on the RAW 264.7 cell line. The bioactive peptides were separated from the whey protein fermentate using reverse-phase high-performance liquid chromatography (RP-HPLC) and reverse-phase liquid chromatography mass spectrometry (RPLC/MS), and thus identification and characterization of purified bioactive peptide was performed.

RESULTS

Whey protein fermentate samples' bioactivity was analyzed at specific time intervals at 12, 24, 36, and 48 hours at 37 °C for M11 and at 25 °C for WBS2A. The development settings (incubation time [12, 24, 36, and 48 hours) and inoculation rates [1.5%, 2.0%, and 2.5%]) were optimized for peptide synthesis via the o-phthaldialdehyde (OPA) method (proteolytic activity). Maximum proteolytic activity was observed at 37 °C for M11 (6.50 mg/mL) and at 25 °C for WBS2A (8.59 mg/mL) for 48 hours of incubation. Protein profiling was carried out using SDS-PAGE and 2D gel electrophoresis, in which Sodium dodecyl-sulfate (SDS) exhibited protein bands in the 10- to 55-kDa range, while 2D showed protein bands varying from 10 to 70 kDa. Every spot from 2D was digested by trypsin and identified by RPLC/MS. Protein fractionations (3- and 10-kDa permeates) were carried out employing RP-HPLC. Whey protein fermentate has anti-inflammatory action in RAW 264.7 macrophages that have been exposed to lipopolysaccharide. A molecular docking system was also used to investigate the interactions of peptides (AFLDSRTR, ILGAFIQIITFR) with human myeloperoxidase enzyme.

CONCLUSIONS

The antihypertensive and antioxidative peptides discovered from whey protein fermentate may be helpful in the design of pharmacologically active healthy ingredients in the upcoming years.

Single and Co-Cultures of Proteolytic Lactic Acid Bacteria in the Manufacture of Fermented Milk with High ACE Inhibitory and Antioxidant Activities

In this study, single and co-cultures of proteolytic Lactobacillus delberueckii subsp. bulgaricus ORT2, Limosilactobacillus reuteri SRM2 and Lactococcus lactis subsp. lactis BRM3 isolated from different raw milk samples were applied as starter cultures to manufacture functional fermented milks. Peptide extracts from fermented milk samples were evaluated after fermentation and 7 days of cold storage for proteolytic, angiotensin-converting enzyme (ACE) inhibitory and antioxidant activity by different methods including 2, 2′-diphenyl-1-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP), OH-radical scavenging, and total antioxidant (molybdate-reducing activity). The highest proteolysis was found in milk fermented by co-cultures of three strains. Fermentation with the mentioned bacteria increased ACE inhibitory and antioxidant activity of the final products which were dependent on peptide concentration. The crude peptide extract obtained from fermented milk with triple co-culture showed the highest ACE inhibitory activity (IC50 = 0.61 mg/mL) which was reduced after 7 days of cold storage (IC50 = 0.78 mg/mL). Similar concentration-dependent activities were found in antioxidant activity at different antioxidant assays. Overall, high proteolytic activity resulted in increased ACE inhibitory and antioxidant activities, but the highest activity was not necessarily found for the samples with the highest proteolytic activity. The results of this study suggest the potential of using co-cultures of L. delberueckii subsp. bulgaricus, L. reuteri and L. lactis subsp. Lactis to manufacture antihypertensive fermented milk.

Characterization of Angiotensin I-Converting Enzyme (ACE) inhibitory peptides produced in fermented camel milk (Indian breed) by Lactobacillus acidophilus NCDC-15

Fermented camel milk provides many health benefits like antidiabetic activity, anti-hypertensive activity etc. Fermented camel milk contains IPP or VPP rich ACE inhibitory peptides. The aim of this study was to spot the novel Angiotensin I-Converting Enzyme inhibitory peptides liberated by the potent proteolytic Lactobacillus acidophilus NCDC-15 from camel milk (Indian breed). NCDC-15 had exhibited maximum PepX activity (0.655) and ACE-inhibitory activity (78.33%) at 12 and 48 h of incubation at 37 °C respectively. Proteolytic activity was measured using o-phthaldialdehyde method and observed maximum (0.976 OD) at 2% of inoculation for 12 h of incubation at 37 °C. Water soluble extracts derived from fermented camel milk were ultrafiltered through 3 kDa, 5 kDa and 10 kDa membrane filters from which 3 kDa permeates (48.01% peptides production & 49.46% ACE-inhibition) and 10 kDa permeates (55.04% peptides production & 42.40% ACE-inhibition) had shown maximum peptides production and ACE-inhibitory activity. Overall, 24 peptides were identified from the samples of 3 kDa permeates [6 fractions (K1, L1, M1, N1, O1 and P1)] and 10 permeates [5 fractions (S, T, U, V and W)]. Novel peptide (AIGPVADLHI) was matched with k-casein in AHTPDB database and other peptides were also found matched with α and β-caseins of camel milk.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05357-9.

Peptidomic profiling of fermented goat milk: considering the fermentation-time dependent proteolysis by Lactobacillus and characterization of novel peptides with Antioxidative activity

In this study, antioxidant activities were evaluated for goat milk fermented with Lactobacillus helveticus MTCC 5463. The fermentation conditions (inoculation rate and incubation time) were optimized by estimating proteolytic action of Lactobacillus. SDS-PAGE and 2D gel electrophoresis were carried out for identification of molecular weight and purification of identified peptides. 3 and 10 kDa peptides fractions were obtained through ultrafiltration and also by using RP-HPLC. Then, spots from 2D and fractions from RP-HPLC were also evaluated in RP-LC/MS for identification and characterization of peptides. Identified peptides were matched with online database of goat milk i.e. BLASTp (NCBI) and Protein information resource database (PIR) and subsequently, antioxidant activity of these peptides were also confirmed with BIOPEP database. However, antioxidative peptides from fermented goat milk with Lactobacillus helveticus MTCC 5463 could be produced in developing functional goat milk yoghurt.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05243-w.

Enhancement of Labneh Quality by Laser-Induced Modulation of Lactocaseibacillus casei NRRL B-1922

Labneh is positioned in the top ranking of the bestselling dairy products all over the world due to its health benefits and delicious taste. Labneh production depends mainly on probiotic bacteria in the fermentation of milk. Probiotic bacteria have many health benefits, which are driven by their selective bioactive metabolites that quantitively affect the fermentation products. The current investigation aimed to study the implementation of photobiomodulation through the irradiation of Lacticaseibacillus casei NRRL-B-1922 by a He–Ne laser (630 nm) with different laser doses (3, 6 & 12 J/cm2) prior to milk fermentation. This procedure sought to improve the probiotic bacteria’s activities while enhancing the labneh’s characteristics and consequently produce a more favorable labneh product with better marketing qualities. The photobiostimulated bacterial starter was found to induce increased titratable acidity with the moisture reduction of the labneh product under cold storage conditions for 20 days. The effect was most prominent when using a 12 J/cm2 laser dose. The flavor-aiding components, mainly diacetyl and acetaldehyde compounds, and sensory scores were increased in the labneh produced by irradiated L. casei when compared to the non-radiated probiotic culture after storing the products under cold conditions for 20 consecutive days. Moreover, the antioxidant and proteolytic activities of labneh produced by treated L. casei (12 J/cm2 laser dose) after cold storage were significantly elevated by 41 and 14%, respectively. In conclusion, we can report significantly improved selected characteristics in the final products after the employment of photobiomodulation process, the potential application of this concept on the industrial scale, and its implications on lengthening the product shelf life with improved qualities.

Nutritional and Volatile Characterisation of Milk Inoculated with Thermo-Tolerant Lactobacillus bulgaricus through Adaptive Laboratory Evolution

In this study, thermo-tolerant strain of Lactobacillus bulgaricus (L. bulgaricus) was developed using gradual increase in temperature to induce Adaptive Laboratory Evolution (ALE). Viable colony count of 1.87 ± 0.98 log cfu/mL was achieved at 52 °C, using MRS agar supplemented with 2% lactose. Changes in bacteria morphology were discovered, from rod (control) to filament (52 °C) to cocci after frozen storage (−80 °C). When milk was inoculated with thermo-tolerant L. bulgaricus, lactic acid production was absent, leaving pH at 6.84 ± 0.13. This has caused weakening of the protein network, resulting in high whey separation and lower water-holding capacity (37.1 ± 0.35%) compared to the control (98.10 ± 0.60%). Significantly higher proteolytic activity was observed through free amino acids analysis by LC-MS. Arginine and methionine (237.24 ± 5.94 and 98.83 ± 1.78 µg/100 g, respectively) were found to be 115- and 275-fold higher than the control, contributing to changing the aroma similar to cheese. Further volatile analysis through SPME-GC-MS has confirmed significant increase in cheese-aroma volatiles compared to the control, with increase in diacetyl formation. Further work on DNA profiling, metabolomics and peptidomics will help to answer mechanisms behind the observed changes made in the study.

Gut microbiota and renin-angiotensin system: a complex interplay at local and systemic levels

Gut microbiota is a potent biological modulator of many physiological and pathological states. The renin-angiotensin system (RAS), including the local gastrointestinal RAS (GI RAS), emerges as a potential mediator of microbiota-related effects. The RAS is involved in cardiovascular system homeostasis, water-electrolyte balance, intestinal absorption, glycemic control, inflammation, carcinogenesis, and aging-related processes. Ample evidence suggests a bidirectional interaction between the microbiome and RAS. On the one hand, gut bacteria and their metabolites may modulate GI and systemic RAS. On the other hand, changes in the intestinal habitat caused by alterations in RAS may shape microbiota metabolic activity and composition. Notably, the pharmacodynamic effects of the RAS-targeted therapies may be in part mediated by the intestinal RAS and changes in the microbiome. This review summarizes studies on gut microbiota and RAS physiology. Expanding the research on this topic may lay the foundation for new therapeutic paradigms in gastrointestinal diseases and multiple systemic disorders.

Effect of Microbial Enzymes on the Changes in the Composition and Microstructure of Hydrolysates from Poultry By-Products

Poultry by-products are promising for the production of protein hydrolysates by enzymatic hydrolysis. The aim of the study is to research the effect of bacterial concentrates on the changes in the amino acid composition and microstructure of poultry by-products during fermentation. Hydrolysis of the gizzards and combs was carried out with a liquid concentrate of bifidobacteria and propionic acid bacteria. As a result of microstructural study of fermented by-products, a decrease in the perception of histological dyes, poor visualization of the cell elements and blurring of the connective tissue matrix were established. During morphometric analyses, we found a reduction in the specific area of connective tissue, the diameter of collagen fibers and the thickness of muscle fibers. A significant effect of the fermentation on the particle size distribution was noted; samples hydrolyzed by microbial enzymes were characterized by a high uniformity of particle sizes and a large number of small particles. Our research revealed an increase in the concentration of free amino acids in the hydrolysates during the fermentation period. The results of biochemical and microscopic analysis confirm the good hydrolysability of hen combs and gizzards under the action of microbial enzymes.

Recent advances in the application of ultrasound in dairy products: Effect on functional, physical, chemical, microbiological and sensory properties

Alternative methods for improving traditional food processing have increased in the last decades. Additionally, the development of novel dairy products is gaining importance due to an increased consumer demand for palatable, healthy, and minimally processed products. Ultrasonic processing or sonication is a promising alternative technology in the food industry as it has potential to improve the technological and functional properties of milk and dairy products. This review presents a detailed summary of the latest research on the impact of high-intensity ultrasound techniques in dairy processing. It explores the ways in which ultrasound has been employed to enhance milk properties and processes of interest to the dairy industry, such as homogenization, emulsification, yogurt and fermented beverages production, and food safety. Special emphasis has been given to ultrasonic effects on milk components; fermentation and spoilage by microorganisms; and the technological, functional, and sensory properties of dairy foods. Several current and potential applications of ultrasound as a processing technique in milk applications are also discussed in this review.

The effect of lactic acid fermentation with different bacterial strains on the chemical composition, immunoreactive properties, and sensory quality of sweet buttermilk

This paper describes the successful development of new low-immunoreactive buttermilk (BM)-based formulations which were fermented with 31 lactic acid bacteria (LAB) and Bifidobacterium strains. The aim of this study was to create a new formula, which can serve as potential candidates for the immunotherapy of allergy. Preparations were tested for their content of biologically active compounds, such as proteins, peptides, phospholipids, and short-chain fatty acids (SCFA), as well as for the survivability of LAB and sensory quality. The results showed that the BM was a matrix rich in nutritional components and displayed higher than expected susceptibility to the reduction of protein IgE-immunoreactivity (to 98%) and high bacterial-protecting capacity. The overall sensory quality of examined products was influenced by the profile of SCFA and free peptides, but two formulations fermented with Lactobacillus delbrueckii ssp. bulgaricus-151 and Lactobacillus casei-LcY were the most advantageous with desirable sensory, immunoreactive, and biochemical properties.

Effect of Lactic Acid Fermentation on Quinoa Characteristics and Quality of Quinoa-Wheat Composite Bread

The application of selected starter cultures with specific properties for fermentation may determine steady lactic acid bacteria (LAB) variety and the characteristics of fermented products that influence nutritional value, the composition of biologically active compounds and quality. The aim of this research was to evaluate the influence of different LAB on the biochemical characteristics of fermented quinoa. Moreover, total phenolic content (TPC), and the antimicrobial and antioxidant activities of protein fractions isolated from quinoa previously fermented with LAB were investigated. Quinoa additives, including quinoa fermented with Lactobacillus brevis, were incorporated in a wheat bread recipe to make nutritionally fortified quinoa-wheat composite bread. The results confirmed that L. plantarum, L. brevis, and L. acidophilus were well adapted in quinoa medium, confirming its suitability for fermentation. LAB strains influenced the acidity, L/D-lactic acid content, enzyme activity, TPC and antioxidant activity of fermented quinoa. The maximum phytase activity was determined in quinoa fermented with L. brevis. The results obtained from the ABTS radical scavenging assay of protein fractions confirmed the influence of LAB strain on the antioxidant activity of protein fractions. The addition of 5 and 10% of quinoa fermented with L. brevis did not affect the total titratable acidity of wheat bread, while 10% of fermented quinoa with L. brevis resulted in a higher specific volume. Fermented quinoa additives increased the overall acceptability of bread compared with unfermented seed additives.

Effect of Low-Immunogenic Yogurt Drinks and Probiotic Bacteria on Immunoreactivity of Cow's Milk Proteins and Tolerance Induction-In Vitro and In Vivo Studies

There is no effective therapy for milk allergy. The role of lactic acid bacteria (LAB) and probiotics in protection against allergy-related outcomes is still under investigation. The aim of the study was to evaluate the immunomodulative and therapeutic potential of yogurt drinks in cow's milk allergy (CMA) management. We compared immunoreactivity of α-casein (α-CN), β-casein (β-CN), κ-casein (κ-CN), α-lactalbumin (α-LA), and β-lactoglobulin (β-LG) in 27 yogurt drinks fermented with different basic yogurt cultures, or yogurt cultures enriched with Lactobacillus plantarum and/or Bifidobacterium lactis strains, by competitive ELISA assay. Drinks with the lowest antigenic potential were used as allergoids for CMA therapy. BALB/c mice were sensitized via intraperitoneal injection of α-CN + β-LG mixture with aluminum adjuvant, and gavaged with increasing doses of selected low-immunogenic drinks (YM-basic, or YM-LB-enriched with L. plantarum and B. lactis) to induce tolerance. Milk- or phosphate-buffered saline (PBS)-dosed mice served as controls. Compared to milk, the immunoreactivity of proteins in drinks increased or decreased, depending on the bacterial sets applied for fermentation. Only a few sets acted synergistically in reducing immunoreactivity. The selected low-immunogenic drinks stimulated allergic mice for profiling Th2 to Th1 response and acquire tolerance, and the effect was greater with YM-LB drink, which during long-lasting interventional feeding strongly increased the secretion of regulatory cytokines, i.e., IL-10 and TGF-β, and IgA and decreased IL-4, IgE, and anti-(α-CN + β-LG) IgG1. The studies revealed variations in the potency of yogurt bacteria to change allergenicity of milk proteins and the need for their strict selection to obtain a safe product for allergy sufferers. The YM-LB drink with reduced antigenic potential may be a source of allergoids used in the immunotherapy of IgE mediated CMA, but further clinical or volunteer studies are required.

The Prospective Beneficial Effects of Red Laser Exposure on Lactocaseibacillus casei Fermentation of Skim Milk

Probiotic lactic acid bacteria are crucial producers of fermented dairy products that are popular functional foods in many countries. The health benefits of probiotic bacteria are mainly attributed to their effective bioactive metabolites. The quality of fermented milk is mainly dependent on the bacterial strain used in the fermentation process. In this study, an innovative technique is used in order to enhance the activities of the probiotic bacteria, quality of fermented milk, and consequently the whole fermentation process. Red laser dosages, at the wavelength of 632.7 nm, were applied to the type strain Lacticaseibacillus casei NRRL-B-1922 before the fermentation of skim milk. The results revealed that the scavenging of 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and total antioxidant capacity were significantly increased from 21% in untreated control to 56% after bacterial laser irradiation of 12 J/cm² dosage for 40 min. The antioxidant activity was found to be increased as the red laser dosage increased in a dose-response relationship. Additionally, the lactose fermentation in skim milk medium of 43.22 mg/mL initial concentration into organic acids was enhanced after L. casei irradiation and recorded 23.15 mg/mL compared to control group 28.35 mg/mL without bacterial pre-treatment. These results are correlated with increase of the β-Galactosidase activity, where the L. casei that has been exposed to 40 min of red laser exhibited the higher activity of a 0.37 unit/mL relative to the control 0.25 unit/mL. The assessment of this fermented milk after L. casei laser exposure for 10, 20, and 40 min indicates multiple biological effects, including assimilation of cholesterol as well as proteolytic and antibacterial activity. Our data on the exposure of L. casei to laser beam suggest promising application of red laser in the fermentation process of skim milk.

Characterization and ACE Inhibitory Activity of Fermented Milk with Probiotic Lactobacillus plantarum K25 as Analyzed by GC-MS-Based Metabolomics Approach

Addition of probiotics to yogurt with desired health benefits is gaining increasing attention. To further understand the effect of probiotic Lactobacillus plantarum on the quality and function of fermented milk, probiotic fermented milk (PFM) made with probiotic L. plantarum K25 and yogurt starter (L. delbrueckii ssp. bulgaricus and Streptococcus thermophilus) was compared with the control fermented milk (FM) made with only the yogurt starter. The probiotic strain was shown to survive well with a viable count of 7.1 ± 0.1 log CFU/g in the PFM sample after 21 days of storage at 4°C. The strain was shown to promote formation of volatiles such as acetoin and 2,3-butanediol with milk fragrance, and it did not cause post-acidification during refrigerated storage. Metabolomics analysis by GC-MS datasets coupled with multivariate statistical analysis showed that addition of L. plantarum K25 increased formation of over 20 metabolites detected in fermented milk, among which γ-aminobutyric acid was the most prominent. Together with several other metabolites with relatively high levels in fermented milk such as glyceric acid, malic acid, succinic acid, glycine, alanine, ribose, and 1,3-dihydroxyacetone, they might play important roles in the probiotic function of L. plantarum K25. Further assay of the bioactivity of the PFM sample showed significant (p < 0.05) increase of ACE inhibitory activity from 22.3% at day 1 to 49.3% at day 21 of the refrigerated storage. Therefore, probiotic L. plantarum K25 could be explored for potential application in functional dairy products.

Cultivable non-starter lactobacilli from ripened Parmigiano Reggiano cheeses with different salt content and their potential to release anti-hypertensive peptides

The impact of salt and fat intake on human health drives the consumer's attention towards dairy food with reduced salt and fat contents. How changes in salt and fat content modulate dairy LAB population and the associated proteolytic activities have been poorly studied. Here, non-starter LAB populations from 12 Parmigiano Reggiano (PR) cheeses (12-month ripened), clustered in low salt and fat content (LL-PR) and high salt and fat content (HH-PR) groups, were investigated and identified at specie-level with molecular assays. Lactobacillus rhamnosus was dominant in HH-PR samples, whereas Lactobacillus paracasei in LL-PR samples. (GTG)₅ rep-PCR analysis discriminated 11 and 12 biotypes for L. rhamnosus and L. paracasei isolates, respectively. Screening for proteolytic activity identified L. rhamnosus strains more proteolytic than L. paracasei, and, within L. rhamnosus species, HH-PR strains were generally more proteolytic than LL-PR strains. Two L. rhamnosus representatives, namely strain 0503 from LL-PR and strain 2006 from HH-PR, were functionally characterized in cow milk fermentation assay. HH-PR strain 2006 overcame LL-PR strain 0503 in acidification performance, leading to a fermented milk with higher angiotensin I-converting enzyme inhibitory and antioxidant activities. L. rhamnosus 2006 was more prone to release VPP, while L. rhamnosus 0503 released higher amount of IPP. This study provides evidences that salt/fat content affects NSLAB cultivable fraction and the associated proteolytic ability resulting in a complex occurrence of bioactive peptides featuring health-promoting properties.

Streptococcus thermophilus alters the expression of genes associated with innate and adaptive immunity in human peripheral blood mononuclear cells

Consumption of probiotics contributes to a healthy microbiome of the GIT leading to many health benefits. They also contribute to the modulation of the immune system and are becoming popular for the treatment of a number of immune and inflammatory diseases. The main objective of this study was to evaluate anti-inflammatory and modulatory properties of Streptococcus thermophilus. We used peripheral blood mononuclear cells from healthy donors and assessed modifications in the mRNA expression of their genes related to innate and adaptive immune system. Our results showed strong immune modulatory effects of S. thermophilus 285 to human peripheral blood mononuclear cells with an array of anti-inflammatory properties. S. thermophilus 285 reduced mRNA expression in a number of inflammatory immune mediators and markers, and upregulated a few of immune markers. S. thermophilus is used in the dairy industry, survives during cold storage, tolerates well upon ingesting, and their consumption may have beneficial effects with potential implications in inflammatory and autoimmune disorders.

Techno-functional characterization of indigenous Lactobacillus isolates from the traditional fermented foods of Meghalaya, India

The rural tribal people of Meghalaya depend mostly on their ethnic fermented foods as a part of their regular diet and these fermented foods are considered to be a hub of healthy microorganisms. However, the efficacy of probiotic microorganisms is considered to be population-specific because of gut microflora variation in food habits and specific host-microbial interactions. Hence, a strong need for exploring novel indigenous microorganisms with rich probiotic potentiality is required. A few indigenous Lactobacillus isolates (from traditional fermented foods of Meghalaya) were studied extensively for its technological and probiotic attributes. The isolates could survive at pH 2–3 (L. fermentum K16 showed high cell count: pH 2–5.12 log CFU/ml; pH 3–5.76 log CFU/ml), against bile salts (L. fermentum K7 showed high cell count-5.36 log CFU/ml), gastric juices (pepsin and trypsin), and intestinal juice (pancreatin). The isolates showed α-galactosidase activity from 0.104-0.412 μM/ml and β-glucosidase activity ranging from 0.122-0.409 μM/ml. Exopolysaccharide production was in between 410 and 950 mg/L. Cell surface hydrophobicity was 71.57% (L. rhamnosus K4E) and auto-aggregation was 83% (L. fermentum K16) during the study. Highest proteolytic activity (0.671 nm) and cholesterol assimilation (52.57%) was exhibited by L. fermentum K16. The isolates showed high free radical scavenging activity by ABTS method up to 80.78% by isolate L. fermentum K7. Antibacterial activity and co-aggregation efficacy was also tested against B. cereus, E. faecalis, S. dysenteriae, S. aureus, E. coli, L. monocytogenes, S. typhi. These indigenous Lactobacillus isolates with high probiotic potentials could be exploited in the development of the traditional fermented foods of Meghalaya.

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Technological and probiotic attributes (in vitro) of eight indigenous Lactobacillus strains were studied.

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Lactobacillus strains were isolated from the traditional fermented foods of Meghalaya, India.

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L. rhamnosus K4E, L. fermentum K16, L. fermentum K7 and L. plantarum RD7 were considered predominant over the rest of the strains.

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The isolates could be employed for development of novel functional fermented foods.

Ex Vivo Study of Laban's Role in Decreasing Hemolysis Crisis in G6PD-Deficient Patients

In spite of the vast nutritional and environmental benefits provided by fava bean (Vicia faba), the ingestion of vicine/convicine provokes an acute hemolytic anemia called favism in individuals with a glucose-6-phosphate dehydrogenase (G6PD) deficiency. The elimination of these glycosides is a goal that could be accomplished using different processing methods including bacteriological treatment. Laban as a good source of lactic acid bacteria was tested in an ex vivo assay on human blood samples in order to determine its capacity in decreasing the hemolysis crisis induced by the ingestion of fava beans. Results indicate a significant decrease in human blood cell hemolysis after the treatment of fava beans by Laban. This decrease in hemolysis was also correlated with the G6PD deficiency categorization. The highest hemolysis level (mean: 23.11 ± 0.76%) was observed in samples with G6PD activity between 10 and 30%, while the lowest hemolysis level (mean: 5.75 ± 0.64%) was observed in samples with G6PD activity more than 60%. This decrease was correlated with a high antioxidant capacity of Laban (51.61 ± 1.13% expressed by the percentage inhibition of DPPH radical). The counts of isolates from MRS and M17 culture plates were 6.75 ± 0.095 and 7.91 ± 0.061 log cfu ml^-1, respectively. In conclusion, the synergy between the antioxidant properties of Laban and the possible decrease of vicine and convicine concentrations by lactobacillus found in the fermented dairy products could explain the ability of Laban to reduce the hemolysis crisis ex vivo.

Cooperation between Lactococcus lactis NRRL B-50571 and NRRL B-50572 for Aroma Formation in Fermented Milk

The aim of the present study was to characterize the aroma and volatile profiles of milk fermented by wild Lactococcus lactis NRRL B-50571 (FM-571) and NRRL B-50572 (FM-572) and co-fermented with both strains (co-FM). Milks fermented by these strains have been reported to have an antihypertensive effect, yet their sensory characteristics, which are of great importance for consumer acceptance of functional foods, have not been studied. In the study, volatiles were determined using solid-phase microextraction gas chromatography mass spectrometry (SPME-GC-MS) and aroma was determined by quantitative descriptive sensory analysis (QDA). Volatile compounds identified in FM-571, FM-572, and co-FM were mainly acids, alcohols, aldehydes, and ketones. FM-571 showed higher total relative volatile abundance than FM-572 or co-FM. Furthermore, the concentrations of specific amino acids (aa) were lower in FM-571 and co-FM than in FM-572. Thus, these results suggested that FM-571 or co-FM are more efficient in transforming specific aa into the corresponding volatiles than FM-572. Indeed, several alcohols and aldehydes, associated with the catabolism of these aa, were found in FM-571 and co-FM, but not in FM-572. Additionally, QDA showed that FM-571 and co-FM presented higher yeasty and cheesy aroma descriptors than FM-572. Also, total aroma intensity scores for FM-571 were higher than those for co-FM or FM-572. Thus, results suggested that the combination of these two specific wild L. lactis strains may complement amino acid catabolic routes that resulted in the enhancement or attenuation of aroma production of single strains, presenting new possibilities for the preparation of custom-made starter cultures.

Antihypertensive Peptide Activity in Dutch-Type Cheese Models Prepared with Different Additional Strains of Lactobacillus Genus Bacteria

The objective of this study was to determine the proteolytic activity of bacterial strains from the genus Lactobacillus and their capability in producing peptide inhibitors of angiotensin-converting enzyme (ACE) in cheese models prepared with their addition. After 5 weeks of ripening, all cheese models studied were characterized by a high ability of angiotensin convertase inhibition which exceeded 80%. The use of the adjunct bacterial cultures from the genus Lactobacillus contributed to lower IC50 values compared with the value determined for the control cheese model. The proteolytic activity of model cheeses varied in their increase through the period of ripening, with changes in values dependent on the adjunct lactic acid bacteria (LAB) strain used for cheesemaking. Starting from the first week of ripening, the lowest proteolytic activity was demonstrated for the control cheese models, whereas the highest activity throughout the ripening period was shown for the cheese models with the addition of Lb. rhamnosus 489.

Comparative studies of versatile extracellular proteolytic activities of lactic acid bacteria and their potential for extracellular amino acid productions as feed supplements

BACKGROUND

Increasing understanding on the functions of amino acids (AA) has led to new commercial applications and expansion of the worldwide markets. However, the current technologies rely heavily on non-food grade microorganism and chemical synthesis for the production of AA. Several studies reported that lactic acid bacteria (LAB) have the capability of producing AA owing to their well-established proteolytic system and amino acid biosynthesis genes. Hence, the objectives of this study were to explore the extracellular proteolytic activity of LAB isolated from various Malaysian fermented foods and their potential to produce AA extracellularly as feed supplements.

RESULTS

All the studied LAB isolates were versatile extracellular protease producers, whereby extracellular protease activities were detected from acidic to alkaline pH (pH 5, pH 6.5, pH 8) using qualitative and quantitative proteolytic assays. The highest proteolytic activity at pH 5 (15.76 U/mg) and pH 8 (19.42 U/mg) was achieved by Lactobacillus plantarum RG14, while Lactobacillus plantarum RS5 exhibited the highest proteolytic activity of 17.22 U/mg at pH 6.5. As for the results of AA production conducted in de Man, Rogosa and Sharpe medium and analysed by high pressure liquid chromatography system, all LAB isolates were capable of producing an array of AA. Generally, Pediococcus sp. showed greater ability for AA production as compared to Lactobacillus sp. Moreover, the studied LAB were able to produce a few major feed supplement AA such as methionine, lysine, threonine and tryptophan. P. pentosaceus TL-3 recorded the highest methionine and threonine productivity of 3.72 mg/L/h and 5.58 mg/L/h respectively. However, L. plantarum I-UL4 demonstrated a lysine productivity of 1.24 mg/L/h, while P. acidilactici TP-6 achieved up to 1.73 mg/L/h of tryptophan productivity.

CONCLUSION

All the 17 studied LAB isolates possessed versatile extracellular proteolytic system and have vast capability of producing various amino acids including a few major feed supplement AA such as methionine, lysine, threonine and tryptophan. Despite AA production was strain dependent, the studied LAB isolates possessed vast potential and can be exploited further as a bio-agent or an alternative amino acids and bioactive peptide producers.

Fermente Süt Ürünlerinin Kan Basıncını Düşürücü Etkisi

Hypertension (HTN) is a major risk factor for the development of cardiovascular diseases. Therefore, there is a need to lower blood pressure (BP) to reduce the risk of these degenerative diseases. Fermented milks contain several potential factors that can lower BP including calcium and microbial metabolites particularly the angiotension-converting enzyme (ACE) inhibitory peptides and γ-aminobutyric acid. &nbsp;Animal studies clearly demonstrated the BP lowering effect of fermented milk while results from clinical trials were controversial due to a large number of variables that should be considered in clinical trials. An overview on the antihypertensive effect of fermented milk products is presented and discussed in this review.