Identification of soybean peptides and their effect on the growth and metabolism of Limosilactobacillus reuteri LR08

Potential Probiotic Properties and Complete Genome Analysis of Limosilactobacillus reuteri LRA7 from Dogs

This study aimed to isolate and screen canine-derived probiotics with excellent probiotic properties. Strain characterization was conducted using a combination of in vitro and in vivo probiotic characterization and safety assessments, as well as complete genome analysis. The results showed that Limosilactobacillus reuteri LRA7 exhibited excellent bacteriostatic and antioxidant activities. The survival rate at pH 2.5 was 79.98%, and the viable counts after exposure to gastrointestinal fluid and 0.5% bile salts were 7.77 log CFU/mL and 5.29 log CFU/mL, respectively. The bacterium also exhibited high hydrophobicity, self-coagulation, and high temperature tolerance, was negative for hemolysis, and was sensitive to clindamycin. In vivo studies in mice showed that the serum superoxide dismutase activity level was 53.69 U/mL higher in the MR group of mice compared to that of the control group, the malondialdehyde content was 0.53 nmol/mL lower in the HR group, and the highest jejunal V/C value was 4.11 ± 1.05 in the HR group (p < 0.05). The L. reuteri LRA7 gene is 2.021 megabases in size, contains one chromosome and one plasmid, and is annotated with 1978 functional genes. In conclusion, L. reuteri LRA7 has good probiotic potential and is safe. It can be used as an ideal probiotic candidate strain of canine origin.

The growth-promoting effects of protein hydrolysates and their derived peptides on probiotics: structure-activity relationships, mechanisms and future perspectives

Lactic acid bacteria (LAB) are the main probiotics currently available in the markets and are essential for maintaining gut health. To guarantee probiotic function, it is imperative to boost the culture yield of probiotic organisms, ensure the sufficient viable cells in commercial products, or develop effective prebiotics. Recent studies have shown that protein hydrolysates and their derived peptides promote the proliferation of probiotic in vitro and the abundance of gut flora. This article comprehensively reviews different sources of protein hydrolysates and their derived peptides as growth-promoting factors for probiotics including Lactobacillus, Bifidobacterium, and Saccharomyces. We also provide a preliminary analysis of the characteristics of LAB proteolytic systems focusing on the correlation between their elements and growth-promoting activities. The structure-activity relationship and underlying mechanisms of growth-promoting peptides and their research perspectives are thoroughly discussed. Overall, this review provides valuable insights into growth-promoting protein hydrolysates and their derived peptides for proliferating probiotics in vivo or in vitro, which may inspire researchers to explore new options for industrial probiotics proliferation, dairy products fermentation, and novel prebiotics development in the future.

Investigating the antibacterial mode of Limosilactobacillus reuteri LR08 regulated by soybean proteins and peptides

Soybean proteins (pro) and soybean peptides (pep) are beneficial to the growth and metabolism of Limosilactobacillus reuteri (L. reuteri). However, whether they could assist L. reuteri in inhibiting intestinal pathogens and the inhibition mode of them is still unclear. In this study, a co-culture experiment of L. reuteri LR08 with Escherichia coli JCM 1649 (E. coli) was performed. It showed that pro and pep could still favour the growth of L. reuteri over E. coli under their competition. The inhibition zone experiment showed the digested soybean proteins (dpro) could improve its antibacterial activity by increasing the secretion of organic acids from L. reuteri. Furthermore, digested soybean peptides (dpep) could enhance nitrogen utilization capacity of L. reuteri over E. coli. These results explained the patterns of dpro and dpep assisting L. reuteri in inhibiting the growth of E. coli by regulating its organic acid secretion and the ability of nitrogen utilization.

Effect of soybean proteins and peptides on the growth and adhesive ability of Limosilactobacillus Reuteri DSM17938

Limosilactobacillus reuteri DSM17938 is one of the most pivotal probiotics, whose general beneficial effects on the intestinal microbiota are well recognized. Enhancing their growth and metabolic activity can effectively regulate the equilibrium of intestinal microbiota, leading to improved physical health. A common method to promote the growth of Lactobacillus is the addition of prebiotics. Current research suggests that proteins and their hydrolysates from different sources with potential prebiotic activity can also promote the growth of probiotics. In this study, soybean proteins and peptides were effective in promoting the growth, organic acid secretion, and adhesive properties of Limosilactobacillus reuteri DSM17938 to Caco-2 cells. These results illustrate the feasibility of soybean proteins and peptides as prebiotics, providing theoretical and practical advantages for their application.

The investigation of soybean protein isolates and soybean peptides assisting Lactobacillus plantarum K25 to inhibit Escherichia coli

Soybean protein isolates and their hydrolysates are considered as one of the most high-quality proteins among plant proteins, and current research has shown that they have potential probiotic functions. The purpose of this study was to investigate the effects of digested soybean protein isolates (dSPI) and digested soybean peptides (dPEP) on L. plantarum K25 alone and the two bacteria when co-cultured with E. coli. It showed that dSPI and dPEP promoted the growth and metabolism of L. plantarum K25, and dSPI had a better effect. Besides, dSPI and dPEP still promoted the growth and organic acid secretion of L. plantarum K25 when co-cultured with E. coli, and the dPEP treatment was more effective than dSPI. Moreover, dSPI and dPEP reduced the survival rate of E. coli when co-cultured with L. plantarum K25. These results to some extent explained the cooperation of dSPI and dPEP with L. plantarum K25 to produce acid thereby weaken the growth of E. coli.

Can proteins, protein hydrolysates and peptides cooperate with probiotics to inhibit pathogens?

Studies have shown that probiotics can effectively inhibit pathogens in the presence of proteins, protein hydrolysates and peptides (protein derivates). However, it is still unclear the modes of probiotics to inhibit pathogens regulated by protein derivates. Therefore, we summarized the possible effects of protein derivates from different sources on probiotics and pathogens. There is abundant evidence that proteins and peptides from different sources can significantly promote the proliferation of probiotics and increase their secretion of antibacterial substances. Such proteins and peptides can also stimulate the adhesion of probiotics to intestinal epithelial cells and contribute to regulating intestinal immunity, but they seem to have the negative effects on pathogens. Moreover, a direct effect of proteins on intestinal cells is summarized. Whether or not they can cooperate with probiotics to inhibit pathogens using above possible mechanisms were discussed. Furthermore, there seems to be no consistent conclusions that protein derivates have synergistic effects with probiotics, and there is still limited evidence on the inhibiting patterns. Therefore, the existing problems and shortcomings are noted, and future research direction is proposed.

The beneficial potential of protein hydrolysates as prebiotic for probiotics and its biological activity: a review

Probiotics are not only a food supplement, but they have shown great potential in their nutritional, health and therapeutic effects. To maximize the beneficial effects of probiotics, it is commonly achieved by adding prebiotics. Prebiotics primarily comprise indigestible carbohydrates, specific peptides, proteins, and lipids, with oligosaccharides being the most extensively studied prebiotics. However, these rapidly fermenting oligosaccharides have many drawbacks and can cause diarrhea and flatulence in the body. Hence, the exploration of new prebiotic is of great interest. Besides oligosaccharides, protein hydrolysates have been demonstrated to enhance the expression of beneficial properties of probiotics. Consequently, this paper outlines the mechanism underlying the action of protein hydrolysates on probiotics, as well as the advantageous impacts of proteins hydrolysates derived from various food sources on probiotics. In addition, this paper also reviews the currently reported biological activities of protein hydrolysates. The aim is a theoretical basis for the development and implementation of novel prebiotics.

Interactive effects of polyethylene microplastics and cadmium on growth of Glycine max

The interaction of microplastics (MPs) and heavy metals (HMs) can lead to aggravation of detrimental effects in the plants, animals, and even human beings. Keeping this in view, the present study was designed to assess the combined toxic effects of polyethylene MPs (PE-MPs) and cadmium (Cd) on germination indices and seedling growth of soybean (Glycine max). Particle sizes of 13 and 6.5 μm and six treatments (control, Cd, 6.5 μm PE, 6.5 μm PE + Cd, 13 μm PE, and 13 μm PE + Cd) were set to simulate the effects of PE-MPs and Cd on the growth of soybean when used alone or in combined form. As compared to the control, 6.5 μm PE treatment showed significant effect on most of the germination indices, i.e., decrease in the germination index by 31%, 44% decrease in the vigor index, and 28% decrease in germination rate whereas mean germination time showed no significant differences. Treatment of smaller-size PE-MPs and Cd significantly inhibited both dry and fresh weights. All treatment groups resulted in significant effect on catalase, peroxidase, and superoxide dismutase activities of seedlings depicting adverse effects of interaction of PE-MPs and Cd. Our findings demonstrated the phyto-toxicity of PE-MPs and Cd in G. max, and it would lead to serious implications in human beings. Our study is important as it provides preliminary information regarding MP absorption and their accumulation in different levels of food chain. It can also form the basis for future research on single the combined effects of different types and sizes of MPs and heavy metals on the terrestrial plants.

Preparation of branched RG-I-rich pectin from red dragon fruit peel and the characterization of its probiotic properties

Red dragon fruit peel is a pectin-rich fruit waste that is a potential source of prebiotics and whose different sources and structures will influence its prebiotic function. Thus, we compared the effects of three extraction methods on the structure and prebiotic function of red dragon fruit pectin, the results showed that the citric acid extracted pectin produced a high Rhamnogalacturonan-I (RG-I) region (66.59 mol%) and more side-chains of Rhamnogalacturonan-I ((Ara + Gal)/Rha = 1.25), which can promote bacterial proliferation significantly. The side-chains of Rhamnogalacturonan-I may be an important factor in that pectin can promote the proliferation of B. animalis. Our results provide a theoretical basis for the prebiotic application of red dragon fruit peel.

Identification and characterization of soybean peptides and their fractions used by Lacticaseibacillus rhamnosus Lra05

Soybean peptides were reported to promote the growth and metabolism of Lacticaseibacillus rhamnosus (L. rhamnosus) Lra05. However, the relationship between L. rhamnosus Lra05 and the characteristics of soybean peptides is still unclear. Therefore, digested soybean peptides (dPEP) after 36 h utilization by L. rhamnosus Lra05 were identified and analyzed. We found that L. rhamnosus Lra05 tends to utilize hydrophobic peptides with three to five amino acids residues, and hydrophilic peptides with more than five residues. They also prefer peptides with proline at penultimate C-terminal position or arginine at ultimate C-terminal position. Moreover, fraction 1 (F1) and fraction 7 (F7) acquired from dPEP using RP-HPLC exhibited the strongest growth and metabolism promoting effects, and the utilized characteristics of F1 and F7 were similar with those of dPEP. These results explained why soybean peptides could promote L. rhamnosus to some extent and strengthen theoretical basis for the application of soybean peptides as potential prebiotics.

In vitro and in vivo Studies of Soybean Peptides on Milk Production, Rumen Fermentation, Ruminal Bacterial Community, and Blood Parameters in Lactating Dairy Cows

Soybean peptides (SPs), a feed additive derived from soybean, exhibit nutritional function and biological activity in monogastric animals, but limited studies have been conducted in dairy cows. Our experiments were conducted to evaluate the effects of SPs on the nutrient degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) in vitro and milk production, rumen fermentation and bacterial community, and blood parameters of dairy cows. For in vitro experiment, ruminal fluids were collected from three ruminal cannulated Holstein dairy cows. A total of three levels of SPs (0, 0.38, and 1.92 g/kg DM of SPs) were added to the total mixed ration (TMR). Nutrient degradability and fermentation fluid pH were determined at 24 and 48 h using 3.0 g samples of the substrate. Gas production after 48 h was recorded by an automated trace gas recording system using 0.5 g samples of the substrate. The results showed that DM, NDF, ADF (p < 0.01), and CP (p < 0.05) degradabilities were significantly increased at 1.92 g/kg DM of SPs at 24 h, and asymptotic gas production (p = 0.05) was increased at 48 h. For in vivo experiment, 110 lactating Holstein cows (209.7 ± 65.2 DIM; 37.2 ± 6.4 kg/d milk yield) were randomly assigned to 0 (control group, CON) or 50 g/head/day SPs (SP-supplemented group). Yields of milk (p < 0.05), milk protein (p < 0.05), and milk lactose (0.05 < p < 0.10) increased on SPs supplementation; however, the milk fat percentage decreased (p < 0.05). The concentrations of individual volatile fatty acids (VFAs) (p < 0.05) and superoxide dismutase (SOD) (p < 0.01) were also increased. Rumen bacterial diversity in SP-supplemented cows was higher (p < 0.05). The relative abundances of Rikenellaceae_RC9_gut_group, Butyrivibrio, Selenomonas, and Shuttleworthia were significantly increased and that of Coprococcus was decreased (p < 0.05). Our results showed that supplementing 1.92 g/kg DM of SPs could improve the nutrient degradability in vitro and 50 g/head/day of SPs could improve milk production and antioxidant ability of dairy cows. The rumen bacterial diversity was also enhanced by SP supplementation.

An updated review of functional properties, debittering methods, and applications of soybean functional peptides

Soybean functional peptides (SFPs) are obtained via the hydrolysis of soybean protein into polypeptides, oligopeptides, and a small amount of amino acids. They have nutritional value and a variety of functional properties, including regulating blood lipids, lowering blood pressure, anti-diabetes, anti-oxidant, preventing COVID-19, etc. SFPs have potential application prospects in food processing, functional food development, clinical medicine, infant milk powder, special medical formulations, among others. However, bitter peptides containing relatively more hydrophobic amino acids can be formed during the production of SFPs, seriously restricting the application of SFPs. High-quality confirmatory human trials are needed to determine effective doses, potential risks, and mechanisms of action, especially as dietary supplements and special medical formulations. Therefore, the physiological activities and potential risks of soybean polypeptides are summarized, and the existing debitterness technologies and their applicability are reviewed. The technical challenges and research areas to be addressed in optimizing debittering process parameters and improving the applicability of SFPs are discussed, including integrating various technologies to obtain higher quality functional peptides, which will facilitate further exploration of physiological mechanism, metabolic pathway, tolerance, bioavailability, and potential hazards of SFPs. This review can help promote the value of SFPs and the development of the soybean industry.

Investigating Differential Expressed Genes of Limosilactobacillus reuteri LR08 Regulated by Soybean Protein and Peptides

Soybean protein and peptides have the potential to promote the growth of Lactobacillus, but the mechanisms involved are not well understood. The purpose of this study is to investigate differentially expressed genes (DEGs) of Limosilactobacillus reuteri (L. reuteri) LR08 responding to soybean protein and peptides using transcriptome. The results showed that both digested protein (dpro) and digested peptides (dpep) could enhance a purine biosynthesis pathway which could provide more nucleic acid and ATP for bacteria growth. Moreover, dpep could be used instead of dpro to promote the ABC transporters, especially the genes involved in the transportation of various amino acids. Interestingly, dpro and dpep played opposite roles in modulating DEGs from the acc and fab gene families which participate in fatty acid biosynthesis. These not only provide a new direction for developing nitrogen-sourced prebiotics in the food industry but could also help us to understand the fundamental mechanism of the effects of dpro and dpep on their growth and metabolisms and provides relevant evidence for further investigation.