Improvement of rheological and sensory properties of Lactobacillus helveticus fermented milk by prebiotics.

The fermentation characteristics and aroma-producing properties of Lactobacilli could influence the flavour quality of fermented milk, an important influencing factor of consumers' preference. In this study, fermented milk was prepared using Lactobacillus helveticus and the dynamic changes in the sensory quality of fermented milk throught fermentation were to assess the dynamic changes in sensory quality of fermented milks throughout the fermentation process, including rheological properties and flavour profiles. Styrene, linalool, octanoic acid, and 1-nonanol were considered as the key flavour components during fermentation. The quality of the fermented milk tends to be stabilized after 24-h, showing the minimal off-flavour at 48-h and optimal fermented aroma at 72-h. Three prebiotics (inulin, Galactooligosaccharides and inulin mixed with Galactooligosaccharides) were added to Lactobacillus spiralis fermented milk separately, and the results showed that inulin mixed with Galactooligosaccharides was the most effective group in improving the organoleptic quality of the fermented milk. Overall, the experimental results provide deeper insights into the release and retention of aroma compounds during fermentation and scientific reference for broadening the application of prebiotics and flavour-producing Lactobacilli in fermented milk processing.

Determination of extracellular proteinase in L. helveticus Lh191404 based on whole genome sequencing and proteomics analysis.

Lactobacillus helveticus exhibits a remarkable proteolytic system. However, the etiology of these protein hydrolysis characteristics, whether caused by extracellular proteinases (EP) or cell envelope proteinases (CEP), has been puzzling researchers. In this study, third-generation Nanopore whole genome sequencing and proteomics analysis were used to unravel the root cause of the aforementioned confusion. The genome of L. helveticus Lh191404 was 2,117,643 bp in length, with 67 secreted proteins were found. Combined with proteomic analysis, it was found that the protein composition of extraction from CEP and EP were indeed the same substance. Bioinformatics analysis indicated that the CEP belonged to the PrtH1 Variant (PrtH1_V) genotype by phylogenetic analysis. The three-dimensional structures of various domains within the PrtH1_V-191404 had been characterized, providing a comprehensive understanding of its structural features. Results of proteinase activity showed that the optimal reaction temperature was 40 °C, with a pH of 6.50. These findings suggested that the origin of EP in L. helveticus Lh191404 may be due to CEP being released into the substrate after detaching from the cell wall. This research is of guiding significance for further understanding the operational mechanism of the protein hydrolysis system in lactic acid bacteria.

Effects of Heat-Treated Lactobacillus helveticus CP790-Fermented Milk on Gastrointestinal Health in Healthy Adults: A Randomized Double-Blind Placebo-Controlled Trial.

Probiotic-fermented milk is commonly used to maintain intestinal health. However, the effects of heat-treated fermented milk, which does not contain live microorganisms, on intestinal function are not yet fully understood. This study aimed to investigate whether heat-treated Lactobacillus helveticus CP790-fermented milk affects fecal microbiota and gut health as a "postbiotic". A randomized, double-blind, placebo-controlled trial was conducted in healthy Japanese individuals aged 20-59 years with a tendency toward constipation. Participants consumed 100 mL of either the test beverage (n = 60) or placebo beverage (n = 60) for four weeks. The test beverages were prepared with heat-treated CP790-fermented milk, while the placebo beverages were prepared with nonfermented milk flavored with lactic acid. Fecal samples were analyzed using 16S rRNA gene sequencing. Constipation symptoms were assessed using defecation logs and the Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire. Mood state was also assessed using the Profile of Mood States 2 (POMS2) questionnaire to explore its potential as a "psychobiotic". Desulfobacterota were significantly decreased by CP790-fermented milk intake. PICRUSt2 analysis predicted a decrease in the proportion of genes involved in the sulfate reduction pathway following the consumption of CP790-fermented milk. The CP790-fermented milk intervention significantly improved stool consistency and straining during defecation. These improvements were correlated with a decrease in Desulfobacterota. After the intervention, overall mood, expressed as total mood disturbance, and depression-dejection were significantly better in the CP790 group than in the placebo group. These results suggest that the intake of CP790-fermented milk could be effective in modulating gut microbiota and improving constipation symptoms and mood states.

Assessing the effects of probiotic supplementation, single strain versus mixed strains, on femoral mineral density and osteoblastic gene mRNA expression in rats.

INTRODUCTION: Osteoporosis is a significant health concern characterized by weak and porous bones, particularly affecting menopausal women aged 50 and above, leading to increased risk of hip fractures and associated morbidity and mortality. MATERIALS AND METHODS: We conducted a study to assess the efficacy of single-strain versus mixed-strain probiotic supplementation on bone health using an ovariectomy (OVX) rat model of induced bone loss. The probiotics evaluated were Lactobacillus helveticus (L. helveticus), Bifidobacterium longum (B. longum), and a combination of both. Rats were divided into five groups: SHAM (Control negative), OVX (Control positive), OVX +L. helveticus, OVX + B. longum, and OVX + mixed L. helveticus and B. longum. Daily oral administration of probiotics at 10^8-10^9 CFU/mL began two weeks post-surgery and continued for 16 weeks. RESULTS: Both single-strain and mixed-strain probiotic supplementation upregulated expression of osteoblastic genes (BMP- 2, RUNX-2, OSX), increased serum osteocalcin (OC) levels, and improved bone formation parameters. Serum C-terminal telopeptide (CTX) levels and bone resorption parameters were reduced. However, the single-strain supplementation demonstrated superior efficacy compared to the mixed-strain approach. CONCLUSION: Supplementation with B. longum and L. helveticus significantly reduces bone resorption and improves bone health in OVX rats, with single-strain supplementation showing greater efficacy compared to a mixed-strain combination. These findings highlight the potential of probiotics as a therapeutic intervention for osteoporosis, warranting further investigation in human studies.

Microbial composition and viability of natural whey starters used in PDO Comté cheese-making.

Natural whey starters (NWS) are cultures with undefined multiple-strains species commonly used to speed up the fermentation process of cheeses. The aim of this study was to explore the diversity and the viability of Comté cheese NWS microbiota. Culture-dependent methods, i.e. plate counting and genotypic characterization, and culture-independent methods, i.e. qPCR, viability-qPCR, fluorescence microscopy and DNA metabarcoding, were combined to analyze thirty-six NWS collected in six Comté cheese factories at two seasons. Our results highlighted that NWS were dominated by Streptococcus thermophilus (ST) and thermophilic lactobacilli. These species showed a diversity of strains based on Rep-PCR. The dominance of Lactobacillus helveticus (LH) over Lactobacillus delbrueckii (LD) varied depending on the factory and the season. This highlighted two types of NWS: the type-ST/LD (LD > LH) and the type-ST/LH (LD < LH). The microbial composition varied depending on cheese factory. One factory was distinguished by its level of culturable microbial groups (ST, enterococci and yeast) and its fungi diversity. The approaches used to estimate the viability showed that most NWS cells were viable. Further investigations are needed to understand the microbial diversity of these NWS.

Evaluation of Probiotic Properties and Safety of Lactobacillus helveticus LH10 Derived from Vinegar through Comprehensive Analysis of Genotype and Phenotype.

The probiotic potential of Lactobacillus helveticus LH10, derived from vinegar Pei, a brewing mixture, was assessed through genotype and phenotype analyses. The assembled genome was comprised of 1,810,276 bp and predicted a total of 2044 coding sequences (CDSs). Based on the whole genome sequence analysis, two bacteriocin gene clusters were identified, while no pathogenic genes were detected. In in vitro experiments, L. helveticus LH10 exhibited excellent tolerance to simulated gastrointestinal fluid, a positive hydrophobic interaction with xylene, and good auto-aggregation properties. Additionally, this strain demonstrated varying degrees of resistance to five antibiotics, strong antagonistic activity against four tested pathogens, and no hemolytic activity. Therefore, L. helveticus LH10 holds great promise as a potential probiotic candidate deserving further investigation for its beneficial effects on human health.

Fermentation Characteristics of Fermented Milk with Streptococcus thermophilus CICC 6063 and Lactobacillus helveticus CICC 6064 and Volatile Compound Dynamic Profiles during Fermentation and Storage.

The lactic acid bacteria Streptococcus thermophilus and Lactobacillus helveticus are commonly used as starter cultures in dairy product production. This study aimed to investigate the characteristics of fermented milk using different ratios of these strains and analyze the changes in volatile compounds during fermentation and storage. A 10:1 ratio of Streptococcus thermophilus CICC 6063 to Lactobacillus helveticus CICC 6064 showed optimal fermentation time (4.2 h), viable cell count (9.64 log10 colony-forming units/mL), and sensory evaluation score (79.1 points). In total, 56 volatile compounds were identified and quantified by solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS), including aldehydes, ketones, acids, alcohols, esters, and others. Among these, according to VIP analysis, 2,3-butanedione, acetoin, 2,3-pentanedione, hexanoic acid, acetic acid, acetaldehyde, and butanoic acid were identified as discriminatory volatile metabolites for distinguishing between different time points. Throughout the fermentation and storage process, the levels of 2,3-pentanedione and acetoin exhibited synergistic dynamics. These findings enhance our understanding of the chemical and molecular characteristics of milk fermented with Streptococcus thermophilus and Lactobacillus helveticus, providing a basis for improving the flavor and odor of dairy products during fermentation and storage.

In Vitro Digestibility Assessment of Whey from Goat and Camel Milk Fermented with Lactobacillus helveticus for Use as a Base in Formulating Follow-On Formula.

Follow-on formulas are necessary for newborns that are unable to breastfeed. Thus, the development of formulas more tailored to infants' needs is highly important. Recently, using camel milk, goat milk, and sweet milk whey in the formulation of follow-on formulas has gained researchers' attention. Moreover, developing postbiotic systems to create formulas that mimic human milk, are easy to digest, improve compatibility with an infant's gut, and boost immunity is crucial. Thus, this study aimed to create and assess different formulations using fermented whey from camel and goat milks. The fermentation process involved the use of Lactobacillus helveticus as a probiotic and proteolytic lactic acid bacterium strain. The study monitored the proteolytic activity and antioxidant properties of sweet whey produced from cow, camel, and goat milks during the fermentation process with L. helveticus. Also, three different milk fat blends were recombined using edible vegetable oils (coconut oil, rice bran oil, and canola oil) and then they were used to formulate follow-on formulas with a similar fat composition to human milk. Finally, the prepared formulas were tested for their in vitro digestibility and antioxidant activity before and after digestion. The L. helveticus strain had high proteolytic activity towards whey proteins from all the types of milk used in the study. A fermentation time of 6 h produced a higher proteolytic degree and antioxidant activity than 2 and 4 h of fermentation. No significant differences were observed for proteolytic degree and antioxidant activity between 6 and 12 h of fermentation for the cow, camel, and goat whey samples. Regarding the fat blends, animal milk fat, rice bran oil, and canola oil in a fat combination were essential to provide the required amount of unsaturated fatty acids in the follow-on formulas, especially the linoleic acid-α-linolenic acid (LA:ALA) ratio. Adding coconut oil in small amounts to the follow-on formulas provided the required amounts of saturated fatty acids, especially lauric and meristic acids. The follow-on formula based on cow or goat milk whey fermented with L. helveticus released more free amino acids (mmol tyrosine equivalent mL-1) with high levels of antioxidants compared to unfermented ones. The release of free amino acids in the follow-on formula based on camel milk whey was not affected by fermentation. Our results recommend using L. helveticus in the fermentation of follow-on formulas based on camel and goat whey instead of formulas based on cow milk proteins.

Effect of Lactobacillus helveticus IMAUJBH1 on fat and volatile flavor substances in fermented mutton sausages.

The decomposition and oxidation of fat is essential for the formation and quality of the unique flavor of sausage. To explore the effect of lactic acid bacteria on fat decomposition and oxidation in fermented sausage, free fatty acids and volatile flavor compounds were determined by gas chromatography (GC) and headspace solid-phase microextraction (HS-SPME)-GC-MS, respectively. The results showed that the addition of Lactobacillus helveticus IMAUJBH1 inhibited fat peroxidation and relatively increased the proportion of monounsaturated fatty acids. A total of 47 volatile flavor compounds were detected, including aldehydes, esters, alcohols, and ketones. The content of substances such as hexanal, heptanal, nonanal and 1-octene-3-ol related to lipid oxidation was significantly reduced. The results obtained in this study show that the strain can further affect the flavor of the product by inhibiting the formation of lipid oxidation or peroxide flavor substances to a certain extent.

Characterization of a putative metal-dependent PTP-like phosphatase from Lactobacillus helveticus 2126 / Caracterización de una supuesta fosfatasa similar a PTP dependiente de metales de Lactobacillus helveticus 2126

To date, there are very limited reports on sequence analysis and structure-based molecular modeling of phosphatases produced by probiotic bacteria. Therefore, a novel protein tyrosine-like phosphatase was characterized from L. helveticus 2126 in this study. The purified bacterial phosphatase was subjected to mass spectrometric analysis, and the identity of constructed sequence was analyzed using peptide mass fingerprint. The 3-D structure of protein was elucidated using homology modeling, while its stability was assessed using Ramachandran plot, VERIFY 3D, and PROCHECK. The bacterium produced an extracellular phosphatase of zone diameter 15 ± 0.8 mm on screening medium within 24 h of incubation. This bacterial phosphatase was highly specific towards sodium phytate as it yielded the lowest Km value of 299.50 ± 4.95 μM compared to other phosphorylated substrates. The activity was effectively stimulated in the presence of zinc, magnesium, and manganese ions thereby showing its PTP-like behavior. The phosphatase showed a molecular mass of 43 kDa, and the corresponding M/Z ratio data yielded 46% query coverage to Bacillus subtilis (3QY7). This showed a 61.1% sequence similarity to Ligilactobacillus ruminis (WP_046923835.1). The final sequence construct based on these bacteria showed a conserved motif “HCHILPGIDD” in their active site. In addition, homology modeling showed a distorted Tim barrel structure with a trinuclear metal center. The final model after energy minimization showed 90.9% of the residues in the favorable region of Ramachandran’s plot. This structural information can be used in genetic engineering for improving the overall stability and catalytic efficiency of probiotic bacterial phosphatases.(AU)

Effect of exopolysaccharides yield and addition concentration of Lactobacillus helveticus on the processing characteristics of fermented milk and its mechanism.

Exopolysaccharides (EPS) yield and added concentration of lactic acid bacteria can greatly affect the processing characteristics of fermented milk. In order to investigate the effects and mechanisms of EPS yield and added concentration on fermented milk, researchers extracted EPS from 50 strains of Lactobacillus helvedicus (L. helvedicus) and selected the two strains with the largest difference in EPS yield (L. helvedicus LH18 and L. helvetigus LH33) for subsequent experiments. The physicochemical properties of EPS-LH18 and EPS-LH33 were analyzed. The gel characteristics and protein conformation of fermented milk were studied by means of texture analyzer, rheometer, scanning electron microscopy, nuclear magnetic resonance machine, fluorescence spectrophotometer and circular dichroism. The results indicate that the monosaccharide compositions of EPS-LH18 and EPS-LH33 are the same and have good thermal stability. The texture and rheological properties of L. helveticus LH18 fermented milk are significantly superior to other fermented milk. The reason is that L. helveticus LH18 EPS has the highest yield, which leads to a denser gel structure, lower surface hydrophobicity and free sulfhydryl content of its fermented milk. According to circular dichroism analysis, ß- sheet and random coil are the internal factors leading to the difference in fermented milk gel. In addition, the fermented milk improved even more favorably as the concentration of the two EPS additions increased. As described above, L. helveticus LH18 has the potential to be an excellent yogurt starter, and both of the above EPS can be used as probiotic stabilizer alternatives for fermented dairy products.

Fabrication of UF-white cheese: Obtaining a different proteolysis rate, texture, and flavor via using combinations of mesophilic starter culture and Lactobacillus helveticus.

The effect of using mesophilic starter culture (Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris) and Lactobacillus helveticus (L. helveticus) at different ratios (100:0, 75:25, 50:50, 25:75, and 0:100) on the quality properties of UF-white cheese during 90 days of ripening was studied. The results revealed that an increase in L. helveticus ratio caused a significant decrease in the pH and total protein contents of the cheeses (p < .05). No significant changes were observed in the dry matter content of the cheeses (p > .05). The use of higher ratios of L. helveticus led to a noticeable increase in proteolysis and lipolysis indices in the cheeses (p < .05). The cheese produced with higher ratios of L. helveticus had less storage (G') and loss (G″) moduli compared to other cheeses. The more open structure was seen in the cheeses produced using higher ratios of L. helveticus. Regarding sensory properties, lower scores of body and texture, and higher scores of odor and flavor were assigned to the cheeses produced using higher ratios of L. helveticus. In conclusion, the use of combinations of mesophilic starter culture and L. helveticus at specific ratios (75:25 and 25:75) led to improve quality characteristics of UF-white cheese.

Characterization of a putative metal-dependent PTP-like phosphatase from Lactobacillus helveticus 2126.

To date, there are very limited reports on sequence analysis and structure-based molecular modeling of phosphatases produced by probiotic bacteria. Therefore, a novel protein tyrosine-like phosphatase was characterized from L. helveticus 2126 in this study. The purified bacterial phosphatase was subjected to mass spectrometric analysis, and the identity of constructed sequence was analyzed using peptide mass fingerprint. The 3-D structure of protein was elucidated using homology modeling, while its stability was assessed using Ramachandran plot, VERIFY 3D, and PROCHECK. The bacterium produced an extracellular phosphatase of zone diameter 15 ± 0.8 mm on screening medium within 24 h of incubation. This bacterial phosphatase was highly specific towards sodium phytate as it yielded the lowest Km value of 299.50 ± 4.95 µM compared to other phosphorylated substrates. The activity was effectively stimulated in the presence of zinc, magnesium, and manganese ions thereby showing its PTP-like behavior. The phosphatase showed a molecular mass of 43 kDa, and the corresponding M/Z ratio data yielded 46% query coverage to Bacillus subtilis (3QY7). This showed a 61.1% sequence similarity to Ligilactobacillus ruminis (WP_046923835.1). The final sequence construct based on these bacteria showed a conserved motif "HCHILPGIDD" in their active site. In addition, homology modeling showed a distorted Tim barrel structure with a trinuclear metal center. The final model after energy minimization showed 90.9% of the residues in the favorable region of Ramachandran's plot. This structural information can be used in genetic engineering for improving the overall stability and catalytic efficiency of probiotic bacterial phosphatases.

Effects of the combination of Lactobacillus helveticus and isomalto-oligosaccharide on survival, gut microbiota, and immune function in Apis cerana worker bees.

The adult worker bees were fed sucrose syrup or sucrose syrup supplemented with Lactobacillus helveticus KM7, prebiotic isomalto-oligosaccharide (IMO), or L. helveticus KM7 combined with IMO. Survival rate, gut microbiota, and gene expression of gut antimicrobial peptides in worker honey bees were determined. Administration of L. helveticus KM7 and IMO significantly increased the survival rate in worker bees relative to bees fed sucrose only. Then, higher concentration of both lactic acid bacteria and Bifidobacterium in the gut and lower counts of gut fungi, Enterococcus, and Bacteroides-Porphyromonas-Prevotella were observed in bees fed the combination of KM7 and IMO compared with control bees. The combination of L. helveticus KM7 with IMO showed a greater or comparable modulating effect on those bacteria relative to either KM7 or IMO alone. Furthermore, the combination treatment of L. helveticus KM7 and IMO enhanced mRNA expression of antimicrobial peptide genes, including Abaecin, Defensin, and the gene encoding prophenoloxidase (PPO) in the gut compared with both control bees and those either L. helveticus KM7 or IMO alone. These results suggest that the combination of L. helveticus KM7 and IMO synergistically modifies the gut microbiota and immunity and consequently improves the survival rate of Apis cerana adult workers.

Intraspecific microdiversity and ecological drivers of lactic acid bacteria in naturally fermented milk ecosystem.

Traditional fermented milks are produced by inoculating technique, which selects well-adapted microorganisms that have been passed on through generations. Few reports have used naturally fermented milks as model ecosystems to investigate the mechanism of formation of intra-species microbial diversity. Here, we isolated and whole-genome-sequenced a total of 717 lactic acid bacterial isolates obtained from 12 independent naturally fermented milks collect from 12 regions across five countries. We further analyzed the within-sample intra-species phylogenies of 214 Lactobacillus helveticus isolates, 97 Lactococcus lactis subsp. lactis isolates, and 325 Lactobacillus delbrueckii subsp. bulgaricus isolates. We observed a high degree of intra-species genomic and functional gene diversity within-/between-sample(s). Single nucleotide polymorphism-based phylogenetic reconstruction revealed great within-sample intra-species heterogeneity, evolving from multiple lineages. Further phylogenetic reconstruction (presence-absence gene profile) revealed within-sample inter-clade functional diversity (based on carbohydrate-active enzyme- and peptidase-encoding genes) in all three investigated species/subspecies. By identifying and mapping clade-specific genes of intra-sample clades of the three species/subspecies to the respective fermented milk metagenome, we found extensive potential inter-/intra-species horizontal gene transfer events. Finally, the microbial composition of the samples is closely linked to the nucleotide diversity of the respective species/subspecies. Overall, our results contribute to the conservation of lactic acid bacteria resources, providing ecological insights into the microbial ecosystem of naturally fermented dairy products.

Improvements of Age-Related Cognitive Decline in Mice by Lactobacillus helveticus WHH1889, a Novel Strain with Psychobiotic Properties.

A gradual decline in cognitive function occurs with age. Accumulating evidence suggests that certain probiotic strains exert beneficial effects on age-related cognitive decline. Our previous study revealed that Lactobacillus helveticus WHH1889 attenuated symptoms of anxiety and depression in depressed mice via shaping the 5-hydroxytryptamine (5-HT) and 5-hydroxytryptophan (5-HTP) metabolism and gut microbial community, indicating the psychobiotic potential of WHH1889. In the present study, the effects of WHH1889 on age-related cognitive decline were investigated. WHH1889 was orally administrated (1 × 109 CFU/day) for twelve weeks in aged mice, and their cognitive behaviors, neurochemical factors, cognitive-related gene expressions, neuroinflammation, and serum tryptophan pathway-targeted metabolic profiling, as well as gut microbiome composition were assessed. WHH1889 demonstrated improvement of the cognitive behaviors via the novel object recognition test (NORT), the active shuttle avoidance test (ASAT), the Y-maze test, and the passive avoidance test (PAT). The hippocampal neuronal loss; the declined concentrations of BDNF, 5-HT, and 5-HTP; the decreased gene expressions of neurodegeneration biomarkers; and the increased production of hippocampal inflammatory cytokines in aged mice were restored by WHH1889. In addition, WHH1889 increased the 5-HT/5HTP levels and decreased the serum levels of tryptophan-derived metabolites (e.g., kynurenine, xanthurenic acid, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid). Furthermore, WHH1889 was revealed to shape the gut microbiota community by reversing the relative abundances of Bacteroidota and Firmicutes. The present findings suggest that L. helveticus WHH1889 exerted cognitive improving effects on aged mice, which was associated with the modulation of 5-HT and 5-HTP metabolism and gut microbial composition. The supplementation of WHH1889 may therefore be a promising therapeutic agent for age-related cognitive deficits.

Effect of NaCl stress on exoproteome profiles of Bacillus amyloliquefaciens EB2003A and Lactobacillus helveticus EL2006H.

Salt stress can affect survival, multiplication and ability of plant growth promoting microorganisms to enhance plant growth. Changes in a microbe's proteome profile is one of the mechanisms employed by PGPM to enhance tolerance of salt stress. This study was focused on understanding changes in the exoproteome profile of Bacillus amyloliquefaciens EB2003A and Lactobacillus helveticus EL2006H when exposed to salt stress. The strains were cultured in 100 mL M13 (B. amyloliquefaciens) and 100 mL De man, Rogosa and Sharpe (MRS) (L. helveticus) media, supplemented with 200 and 0 mM NaCl (control), at pH 7.0. The strains were then incubated for 48 h (late exponential growth phase), at 120 rpm and 30 (B. amyloliquefaciens) and 37 (L. helveticus) °C. The microbial cultures were then centrifuged and filtered sterilized, to obtain cell free supernatants whose proteome profiles were studied using LC-MS/MS analysis and quantified using scaffold. Results of the study revealed that treatment with 200 mM NaCl negatively affected the quantity of identified proteins in comparison to the control, for both strains. There was upregulation and downregulation of some proteins, even up to 100%, which resulted in identification of proteins significantly unique between the control or 200 mM NaCl (p ≤ 0.05), for both microbial species. Proteins unique to 200 mM NaCl were mostly those involved in cell wall metabolism, substrate transport, oxidative stress tolerance, gene expression and DNA replication and repair. Some of the identified unique proteins have also been reported to enhance plant growth. In conclusion, based on the results of the work described here, PGPM alter their exoproteome profile when exposed to salt stress, potentially upregulating proteins that enhance their tolerance to this stress.

Influence of Fermentation by Lactobacillus helveticus on the Immunoreactivity of Atlantic Cod Allergens.

Fermentation techniques may induce alterations in fish allergen immunoreactivity. In this study, the influence of fermentation with three different strains of Lactobacillus helveticus (Lh187926, Lh191404, and Lh187926) on the immunoreactivity of Atlantic cod allergens was investigated via several methods. Gradually reduced protein composition and band intensity due to the fermentation by strain Lh191404 were found in SDS-PAGE analysis, and decreased immunoreactivity of fish allergens was confirmed by Western blotting and ELISA analysis due to the fermentation of strain Lh191404. Additionally, results from nLC-MS/MS and immunoinformatics tools analysis demonstrated that the protein polypeptide and allergen composition of Atlantic cod showed evident alterations after fermentation, with the epitopes of the main fish allergens being heavily exposed and destroyed. These results indicated that the fermentation of L. helveticus Lh191404 could destroy the structure and linear epitopes of the allergens from Atlantic cod and may have considerable potential in mitigating the allergenicity of fish.

Co-cultivation effects of Lactobacillus helveticus SNA12 and Kluveromyces marxiensis GY1 on the probiotic properties, flavor, and digestion in fermented milk.

This study aimed to evaluate inoculating the lactic acid bacteria Lactobacillus helveticus SNA12 and the yeast Kluyveromyces marxiensis GY1 as starter cultures on milk fermentation. In this study, the probiotic properties of L. helveticus SNA12, K. marxiensis GY1 and co-culture of these two strains (L. helveticus SNA12-K. marxiensis GY1) were investigated, and the results showed that K. marxiensis GY1 had better gastrointestinal tolerance, aggregation, and cell adhesion properties than L. helveticus SNA12. After the co-cultivation of two strains, the presence of K. marxiensis GY1 significantly increased the gastrointestinal tolerance, aggregation, and adhesion characteristics of L. helveticus SNA12. In order to investigate the flavor changes, digestive characteristics, and antioxidant properties following co-cultivation fermentation, the optimal fermentation ratio of 8 %-2% (v/v) and fermentation temperature (37 °C) of L. helveticus SNA12-K. marxiensis GY1 were determined. The results of the electronic nose and electronic tongue showed that L. helveticus SNA12-K. marxiensis GY1 could increase the aroma components of fermented milk, such as terpenes and aromatic substances. Meanwhile, dynamic in vitro rat stomach-duodenum model was used to analyse the changes in the digestion of proteins and peptides (<10 kDa), and the results indicated that co-cultivation fermented milk could be digested faster compared to a single fermentation. Furthermore, the antioxidant capacity of co-cultivation fermented milk was higher than that of single fermentation.

Differential behavior of Lactobacillus helveticus B1929 and ATCC 15009 on the hydrolysis and angiotensin-I-converting enzyme inhibition activity of fermented ultra-high-temperature milk and nonfat dried milk powder.

Consumers' growing interest in fermented dairy foods necessitates research on a wide array of lactic acid bacterial strains to be explored and used. This study aimed to investigate the differences in the proteolytic capacity of Lactobacillus helveticus strains B1929 and ATCC 15009 on the fermentation of commercial ultra-pasteurized (UHT) skim milk and reconstituted nonfat dried milk powder (at a comparable protein concentration, 4%). The antihypertensive properties of the fermented milk, measured by angiotensin-I-converting enzyme inhibitory (ACE-I) activity, were compared. The B1929 strain lowered the pH of the milk to 4.13 ± 0.09 at 37°C after 24 h, whereas ATCC 15009 needed 48 h to drop the pH to 4.70 ± 0.18 at 37°C. Two soluble protein fractions, one (CFS1) obtained after fermentation (acidic conditions) and the other (CFS2) after the neutralization (pH 6.70) of the pellet from CFS1 separation, were analyzed for d-/l-lactic acid production, protein concentration, the degree of protein hydrolysis, and ACE-I activity. The CFS1 fractions, dominated by whey proteins, demonstrated a greater degree of protein hydrolysis (7.9%) than CFS2. On the other hand, CFS2, mainly casein proteins, showed a higher level of ACE-I activity (33.8%) than CFS1. Significant differences were also found in the d- and l-lactic acid produced by the UHT milk between the 2 strains. These results attest that milk casein proteins possessed more detectable ACE-I activity than whey fractions, even without a measurable degree of hydrolysis. Findings from this study suggest that careful consideration must be given when selecting the bacterial strain and milk substrate for fermentation.