The stressing life of Lactobacillus delbrueckii subsp. bulgaricus in soy milk

Changes in the Human Gut Microbiome Caused by the Short-Term Impact of Lactic Acid Bacteria Consumption in Healthy People

The gut microbiome is one of the main factors affecting human health. It has been proven that probiotics can regulate the metabolism in the host body. A large number of people use probiotics not as medicines, but as a prophylactic supplement. The aim of our study was to evaluate the effect of lactic acid bacteria on the gut microbiome of healthy people using the V3 region of the 16S rRNA gene. Our study showed changes in the generic composition in the gut of healthy people when taking the supplement. There was an increase in the members responsible for the production of short-chain fatty acids in the gut of the host (Blautia, Fusicatenibacter, Eubacterium hallii group, Ruminococcus), as well as bacteria that improve intestinal homeostasis (Dorea and Barnesiella). There was also a decrease in the abundance of bacteria in the genera Catenibacterium, Hungatella, Escherichia-Shigella, and Pseudomonas, associated with an unhealthy profile of the human gut microbiome. An increase in members of the phylum Actinobacteriota was also observed, which has a positive effect on the host organism. Our results indicate that short-term prophylactic use of lactic acid bacteria-based supplements can be effective, as it contributes to a beneficial effect on the gut microbiome of healthy people.

Lactic acid bacteria in Asian fermented foods and their beneficial roles in human health

Fermented foods have been a staple in human diets for thousands of years, garnering attention for their health and medicinal benefits. Rich in lactic acid bacteria (LAB) with probiotic properties, these foods play a crucial role in positively impacting the host's gut microbiome composition and overall health. With a long history of safe consumption, fermented foods effectively deliver LAB to humans. Intake of LAB from fermented foods offers three main benefits: (1) enhancing digestive function and managing chronic gastrointestinal conditions, (2) modulating the immune system and offering anti-inflammatory effects to prevent immune-related diseases, and (3) synthesizing vitamins and various bioactive compounds to improve human health. In this review, we highlighted the diverse LAB present in Asian fermented foods and emphasized LAB-rich fermented foods as a natural and effective solution for health enhancement and disease prevention.

Deciphering the metabolism of Lactobacillus delbrueckii subsp. delbrueckii during soy juice fermentation using phenotypic and transcriptional analysis

In the context of sustainable diet, the development of soy-based yogurt fermented with lactic acid bacteria is an attractive alternative to dairy yogurts. To decipher the metabolism of Lactobacillus delbrueckii subsp. delbrueckii during soy juice (SJ) fermentation, the whole genome of the strain CIRM-BIA865 (Ld865) was sequenced and annotated. Then Ld865 was used to ferment SJ. Samples were analyzed throughout fermentation for their cell number, carbohydrate, organic acid, free amino acid, and volatile compound contents. Despite acidification, the number of Ld865 cells did not rise, and microscopic observations revealed the elongation of cells from 3.6 µm (inoculation) to 36.9 µm (end of fermentation). This elongation was observed in SJ but not in laboratory-rich medium MRS. Using transcriptomic analysis, we showed that the biosynthesis genes of peptidoglycan and membrane lipids were stably expressed, in line with the cell elongation observed, whereas no genes implicated in cell division were upregulated. Among the main sugars available in SJ (sucrose, raffinose, and stachyose), Ld865 only used sucrose. The transcriptomic analysis showed that Ld865 implemented the two transport systems that it contains to import sucrose: a PTS system and an ABC transporter. To fulfill its nitrogen needs, Ld865 probably first consumed the free amino acids of the SJ and then implemented different oligopeptide transporters and proteolytic/peptidase enzymes. In conclusion, this study showed that Ld865 enables fast acidification of SJ, despite the absence of cell division, leads to a product rich in free amino acids, and also leads to the production of aromatic compounds of interest.

IMPORTANCE

To reduce the environmental and health concerns related to food, an alternative diet is recommended, containing 50% of plant-based proteins. Soy juice, which is protein rich, is a relevant alternative to animal milk, for the production of yogurt-like products. However, soy "beany" and "green" off-flavors limit the consumption of such products. The lactic acid bacteria (LAB) used for fermentation can help to improve the organoleptic properties of soy products. But metabolic data concerning LAB adapted to soy juice are lacking. The aim of this study was, thus, to decipher the metabolism of Lactobacillus delbrueckii subsp. delbrueckii during fermentation of a soy juice, based on a multidisciplinary approach. This result will contribute to give tracks for a relevant selection of starter. Indeed, the improvement of the organoleptic properties of these types of products could help to promote plant-based proteins in our diet.

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

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

Healthy Effects of Milk and Dairy Product Consumption in the Mediterranean Area and Japan

Milk is a food enriched in essential components for human health. Especially, in the Mediterranean area, besides cow's milk, milk from goats, sheep, and donkeys, is largely used. The consumption of animal milk is an important component of the Mediterranean (MED) diet, even if in moderate amounts. Milk is a complete food since it contains proteins, carbohydrates, and fats, as well as micronutrients (minerals and vitamins). Milk-fermented products are largely consumed in the MED diet, such as cheese and yogurt, which are rich in essential metabolites, bioactive compounds, vitamins, minerals, and exopolysaccharides. A large body of evidence suggests that consumption of milk and dairy products does not increase the risk of all-cause mortality, type 2 diabetes, and cardiovascular disease, even if some earlier studies have reported harmful effects associated with their higher consumption. Also, in Japan, despite the lower consumption of milk than in Western countries, intake of bovine milk is associated with healthy effects. The present review describes the effects of the various constituents of animal milk on human health, with special reference to the Mediterranean area and Japan. Experimental data and clinical trials support the ability of milk and dairy products to lower the risk of chronic diseases.

Optimization of Enzyme-Assisted Extraction of Bioactive Compounds from Sea Buckthorn (Hippophae rhamnoides L.) Leaves: Evaluation of Mixed-Culture Fermentation

Hippophae rhamnoides L. leaves possess a remarkable amount of polyphenols that could serve as a natural remedy in various applications. In comparison, numerous techniques, such as conventional and high-pressure techniques, are available for extracting the bioactive fractions from sea buckthorn leaves (SBL). However, enzyme-assisted extraction (EAE) of SBL has not been comprehensively studied. The aim of this study was to optimize critical EAE parameters of SBL using the cellulolytic enzyme complex, Viscozyme L, to obtain a high-yield extract with a high concentration of bioactive compounds. In order to determine the optimal conditions for EAE, the study employed a central composite design and response surface methodology to analyze the effects of four independent factors (pH, temperature, extraction time, and enzyme concentration) on two different responses. Our findings indicated that under optimal conditions (3:15 h extraction, temperature 45 °C, pH 4.9, and 1% Viscozyme L v/w of leaves DW), EAE yielded 28.90 g/100 g DW of the water-soluble fraction. Furthermore, the EAE-optimized liquid extract was continuously fermented using an ancient fermentation starter, Tibetan kefir grains, which possess lactic acid bacteria (LAB) and have significant potential for use in biopreservation. Interestingly, the results indicated various potential prebiotic characteristics of LAB. Additionally, alterations in the cell wall morphology of the SBL residue after EAE were examined using scanning electron microscopy (SEM). This study significantly optimized EAE parameters for sea buckthorn leaves, providing a promising natural source of bioactive compounds for various applications, such as nutraceuticals, functional foods, and high-value products.

Evaluation of the fermentation potential of lactic acid bacteria isolated from herbs, fruits and vegetables as starter cultures in nut-based milk alternatives

Fermentation of plant-based milk alternatives (PBMAs), including nut-based products, has the potential to generate new foods with improved sensorial properties. In this study, we screened 593 lactic acid bacteria (LAB) isolates from herbs, fruits and vegetables for their ability to acidify an almond-based milk alternative. The majority of the strongest acidifying plant-based isolates were identified as Lactococcus lactis, which were found to lower the pH of almond milk faster than dairy yoghurt cultures. Whole genome sequencing (WGS) of 18 plant-based Lc. lactis isolates revealed the presence of sucrose utilisation genes (sacR, sacA, sacB and sacK) in the strongly acidifying strains (n = 17), which were absent in one non-acidifying strain. To confirm the importance of Lc. lactis sucrose metabolism in efficient acidification of nut-based milk alternatives, we obtained spontaneous mutants defective in sucrose utilisation and confirmed their mutations by WGS. One mutant containing a sucrose-6-phosphate hydrolase gene (sacA) frameshift mutation was unable to efficiently acidify almond, cashew and macadamia nut milk alternatives. Plant-based Lc. lactis isolates were heterogeneous in their possession of the nisin gene operon near the sucrose gene cluster. The results of this work show that sucrose-utilising plant-based Lc. lactis have potential as starter cultures for nut-based milk alternatives.

Development of innovative fermented products by exploiting the diversity of immunomodulatory properties and fermentative activity of lactic and propionic acid bacteria

Many consumers nowadays demand plant-based milk analogs for reasons related to lifestyle, health, diet and sustainability. This has led to the increasing development of new products, fermented or not. The objective of the present study was to develop a plant-based fermented product (based on soy milk analog or on hemp milk analog), as well as mixes, using lactic acid bacteria (LAB) and propionic acid bacteria (PAB) strains, as well as consortia thereof. We screened a collection of 104 strains, from nine LAB species and two PAB species, based on their ability to ferment plant or milk carbohydrates, to acidify goat milk, soy milk analog and hemp milk analog, as well as to hydrolyze proteins isolated from these three products. Strains were also screened for their immunomodulatory ability to induce secretion of two interleukins, i.e., IL-10 and IL-12, in human Peripheral Blood Mononuclear Cells. We selected five strains: Lactobacillus delbrueckii subsp. lactis Bioprox1585, Lactobacillus acidophilus Bioprox6307, Lactococcus lactis Bioprox7116, Streptococcus thermophilus CIRM-BIA251, and Acidipropionibacterium acidipropionici CIRM-BIA2003. We then assembled them in 26 different bacterial consortia. Goat milk and soy milk analog fermented by each of the five strains or by the 26 consortia were tested in vitro, for their ability to modulate inflammation in cultured Human Epithelial Intestinal Cells (HEIC) stimulated by pro-inflammatory Lipopolysaccharides (LPS) from Escherichia coli. Plant-based milk analogs, fermented by one consortium composed of L.delbrueckii subsp. lactis Bioprox1585, Lc.lactis Bioprox7116, and A.acidipropionici CIRM-BIA2003, reduced the secretion of the proinflammatory cytokine IL-8 in HIECs. Such innovative fermented vegetable products thus open perspectives as functional foods targeting gut inflammation.

The Biochemical Alteration of Enzymatically Hydrolysed and Spontaneously Fermented Oat Flour and Its Impact on Pathogenic Bacteria

Avena sativa (A. sativa) oats have recently made a comeback as suitable alternative raw materials for dairy substitutes due to their functional properties. Amylolytic and cellulolytic enzyme-assisted modifications of oats produce new products that are more appealing to consumers. However, the biochemical and functional alteration of products and extracts requires careful selection of raw materials, enzyme cocktails, and technological aspects. This study compares the biochemical composition of different A. sativa enzyme-assisted water extracts and evaluates their microbial growth using spontaneous fermentation and the antimicrobial properties of the ferment extracts. Fibre content, total phenolic content, and antioxidant activity were evaluated using traditional methodologies. The degradation of A. sativa flour was captured using scanning electron microscopy (SEM); moreover, sugar and oligosaccharide alteration were identified using HPLC and HPLC-SEC after INFOGEST in vitro digestion (IVD). Additionally, taste differentiation was performed using an electronic tongue with principal component analysis. The oat liquid extracts were continuously fermented using two ancient fermentation starters, birch sap and Tibetan kefir grains. Both starters contain lactic acid bacteria (LAB), which has major potential for use in bio-preservation. In fermented extracts, antimicrobial properties against Gram-positive Staphylococcus aureus and group A streptococci as well as Gram-negative opportunistic bacteria such as Escherichia coli and Pseudomonas aeruginosa were also determined. SEM images confirmed the successful incorporation of enzymes into the oat flour. The results indicate that using enzyme-assisted extraction significantly increased TPC and antioxidant activity in both the extract and residues. Additionally, carbohydrates with a molecular mass (MM) of over 70,000 kDa were reduced to 7000 kDa and lower after the incorporation of amylolytic and cellulolytic enzymes. The MM impacted the variation in microbial fermentation, which demonstrated favourable antimicrobial properties. The results demonstrated promising applications for developing functional products and components using bioprocessing as an innovative tool.