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.

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.

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.

Observational evidence for the non-suppression effect of atmospheric chemical modification on the ice nucleation activity of East Asian dust.

Airborne mineral dust triggers ice formation in clouds and alters cloud microphysical properties by acting as ice-nucleating particles (INPs), potentially influencing weather and climate at regional and global scales. Anthropogenic pollution would modify natural mineral dust during the atmospheric transport process. However, the effects of anthropogenic pollution aging on the ice nucleation activity (INA) of mineral dust remain not well-understood. In this study, we investigated the immersion mode ice nucleation properties and particle chemical characterizations of collected size-resolved Asian dust samples (eight particle size classes ranging from 0.18 to 10.0 µm), and testified the chemical modification of aged dust particles via particle chemistry and morphology analyses including the mass concentrations of particulate matter, the water-soluble ion concentrations, the mental element concentrations, and single-particle morphology. The mass fraction of Ca2+ in element Ca and the mean relative mass proportions of supermicron Ca2+ increased by 67.0 % and 3.5-11.2 % in aged Asian dust particles, respectively, suggesting the occurrence of heterogeneous reactions. On the other hand, the total INP concentrations (total NINP) and total ice nucleation active site densities (total ns(T)) were consistent between aged and normal dust particles (0.62-1.18 times) without a statistically significant difference. And the NINP and ns(T) of chemically aged supermicron dust (1.0-10.0 µm) in each particle size class were nearly equal to or slightly higher than those of normal Asian dust, which were 0.70-2.45 times and 0.64-4.34 times at -18 °C, respectively. These results reveal that anthropogenic air pollution does not notably change the INP concentrations and does not impair the INA of Asian dust. Our work provides direct observational evidence and clarifies the non-suppression effect of anthropogenic air pollution on the INA of East Asian dust, advancing the understanding of the ice nucleation of airborne aged mineral dust.

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.

The Formation, Structural Characteristics, Absorption Pathways and Bioavailability of Calcium-Peptide Chelates.

Calcium is one of the most important mineral elements in the human body and is closely related to the maintenance of human health. To prevent calcium deficiency, various calcium supplements have been developed, but their application tends to be limited by low calcium content and highly irritating effects on the stomach, among other side effects. Recently, calcium-peptide chelates, which have excellent stability and are easily absorbed, have received attention as an alternative emerging calcium supplement. Calcium-binding peptides (CaBP) are usually obtained via the hydrolysis of animal or plant proteins, and calcium-binding capacity (CaBC) can be further improved through chromatographic purification techniques. In calcium ions, the phosphate group, carboxylic group and nitrogen atom in the peptide are the main binding sites, and the four modes of combination are the unidentate mode, bidentate mode, bridging mode and α mode. The stability and safety of calcium-peptide chelates are discussed in this paper, the intestinal absorption pathways of calcium elements and peptides are described, and the bioavailability of calcium-peptide chelates, both in vitro and in vivo, is also introduced. This review of the research status of calcium-peptide chelates aims to provide a reasonable theoretical basis for their application as calcium supplementation products.

Application of Emulsion Gels as Fat Substitutes in Meat Products.

Although traditional meat products are highly popular with consumers, the high levels of unsaturated fatty acids and cholesterol present significant health concerns. However, simply using plant oil rich in unsaturated fatty acids to replace animal fat in meat products causes a decline in product quality, such as lower levels of juiciness and hardness. Therefore, it is necessary to develop a fat substitute that can ensure the sensory quality of the product while reducing its fat content. Consequently, using emulsion gels to produce structured oils or introducing functional ingredients has attracted substantial attention for replacing the fat in meat products. This paper delineated emulsion gels into protein, polysaccharide, and protein-polysaccharide compound according to the matrix. The preparation methods and the application of the three emulsion gels as fat substitutes in meat products were reviewed. Since it displayed a unique separation structure, the double emulsion was highly suitable for encapsulating bioactive substances, such as functional oils, flavor components, and functional factors, while it also exhibited significant potential for developing low-fat or functional healthy meat products. This paper summarized the studies involving the utilization of double emulsion and gelled double emulsion as fat replacement agents to provide a theoretical basis for related research and new insight into the development of low-fat meat products.

An overlooked source of nanosized lead particles in the atmosphere: Residential honeycomb briquette combustion.

Atmospheric lead (Pb) pollution has attracted long-term and widespread concerns due to its high toxicity. The definite source identification of atmospheric Pb is the key step to mitigate this pollution. Here, we first report an overlooked source of atmospheric nanosized Pb particles using transmission electron microscopy and bulk sample analyses, finding that residential honeycomb briquette combustion emits large numbers of nanosized Pb-rich particles. We found that 33.7 ± 19.9 % of primary particles by number from residential honeycomb briquette combustion contains the crystalline Pb particles. These Pb-rich particles range in size from 14 to 956 nm with a mean diameter of 117 nm. Compared with raw coal chunks, honeycomb briquette combustion could emit less carbonaceous particles, but largely increase nanosized Pb particle emissions. This result is attributed to two key factors: (1) higher Pb content in honeycomb briquette (63.6 µg g-1) than that in coal chunk (8.5 µg g-1), and (2) higher Pb release rate for honeycomb briquette (62.3 %) caused by honeycomb structure than that for coal chunk (20.1 %). This study highlights that atmospheric and health implications of high emissions of toxic nanosized Pb from honeycomb briquette should be paid more attention in future research on ambient and indoor airs.

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.

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

Lactic acid bacteria are one of the most pivotal probiotics. Promoting their viability could be an effective method to modulate the balance of intestinal flora, thereby improving human health. The current solution is to take advantage of carbon-sourced prebiotics, while protein and peptides with potential prebiotic functions have not been investigated. Soy proteins and peptides have been proven to enhance the growth and metabolism of Lactobacillus. However, research on the relationship between strains of lactobacilli and the structure of soybean peptides is still limited. In the present study, soybean protein and peptides effectively increased the growth and organic acid secretion of Limosilactobacillus reuteri LR08. Additionally, soybean peptides and fructooligosaccharides showed synergistic effects in modulating Limosilactobacillus reuteri LR08. Fraction 1 acquired from soy peptides using RP-HPLC exhibited the most effectiveness and several novel peptides were identified. These results could theoretically and practically benefit soybean peptide application as a potential prebiotic.

Differences in the gut microbiota composition of rats fed with soybean protein and their derived peptides.

Current studies regarding the effect of different nitrogen sources on gut microbiota have thus far disregarded the ability of probiotics and coliforms to compete for protein. This study aimed to investigate the differences in the utilization of soybean protein (SPro) and its derived peptides (SPep) by the gut microbiota of Sprague Dawley (SD) rats. The SPro and SPep prepared in this study showed extensive SPro molecular weight distribution, while that of SPep was minimal, ranging between 150 and 1000 Da and primarily consisting of two to five amino acids. The cecum microflora composition of the rats was determined via 16S rDNA amplicon sequencing, showing that the SPro and SPep significantly increased the abundance and uniformity of the gut microbiota after 35 days of feeding. The Firmicutes/Bacteroidetes (F/B) ratios of the SPep, SPro, and casein groups were 2.49 ± 0.60, 2.98 ± 1.12, and 2.59 ± 0.74, respectively. Although the rats fed with SPro and SPep displayed similar gut microbiome structures, SPep significantly promoted Lactobacillus and Phascolarctobacterium growth. The results showed that SPep significantly increased the diversity of the gut microbiota and elevated the probiotic proportion. PRACTICAL APPLICATION: SPro and SPep are two nutritious and high-quality nitrogen sources. The results showed that SPro and SPep regulated the structure of gut microbiota in rats, and the effect of SPep was better. This study provides a theoretical basis for developing SPep functional foods able to regulate gut microbiota and maintain health.

Different effects of soybean protein and its derived peptides on the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190.

Bifidobacterium is a common probiotic that plays a vital role in the intestinal tract. This study aimed to explore the different effects of soybean protein and soybean peptides on the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190. Soybean protein and soybean peptides were digested in vitro, after which different nitrogen source containing media were prepared and used for the monoculture of Bifidobacterium animalis subsp. animalis JCM 1190 and the co-culture of Bifidobacterium animalis subsp. animalis JCM 1190 and Escherichia coli JCM 1649. During the culture process, the viable cell number and lactic acid and acetic acid contents were measured, while non-targeted metabonomics was used to detect the differential metabolites and metabolic pathways. The results showed that soybean protein and soybean peptides promoted the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190, while digested soybean peptides had a better effect. Digested soybean peptides increased the viable cell number and lactic acid and acetic acid contents in the monoculture by regulating glycine, serine, and threonine metabolism, as well as pyruvate metabolism, the TCA cycle, glycolipid metabolism, and other metabolic pathways, balanced the ability of Bifidobacterium animalis subsp. animalis JCM 1190 and Escherichia coli JCM 1649 to utilize nitrogen sources during the early period and enhanced the competitiveness of Bifidobacterium animalis subsp. animalis JCM 1190 during the later period in co-culture.

Chemistry of Atmospheric Fine Particles During the COVID-19 Pandemic in a Megacity of Eastern China.

Air pollution in megacities represents one of the greatest environmental challenges. Our observed results show that the dramatic NOx decrease (77%) led to significant O3 increases (a factor of 2) during the COVID-19 lockdown in megacity Hangzhou, China. Model simulations further demonstrate large increases of daytime OH and HO2 radicals and nighttime NO3 radical, which can promote the gas-phase reaction and nocturnal multiphase chemistry. Therefore, enhanced NO3 - and SO4 2- formation was observed during the COVID-19 lockdown because of the enhanced oxidizing capacity. The PM2.5 decrease was only partially offset by enhanced aerosol formation with its reduction reaching 50%. In particular, NO3 - decreased largely by 68%. PM2.5 chemical analysis reveals that vehicular emissions mainly contributed to PM2.5 under normal conditions in Hangzhou. Whereas, stationary sources dominated the residual PM2.5 during the COVID-19 lockdown. This study provides evidence that large reductions in vehicular emissions can effectively mitigate air pollution in megacities.

Fine particles from village air in northern China in winter: Large contribution of primary organic aerosols from residential solid fuel burning.

Rural residential emissions contribute significantly to regional air pollution in China, but our understanding on how residential solid fuel burning influences the village outdoor air quality is limited. In this study, we compared the fine particulate matter (PM2.5) composition and individual particle characteristics from 11 to 18 January 2017 at a village and an urban site in northern China. At the village site, each day was divided into four periods: cooking (07:30-10:00; 16:00-17:00), daytime (10:00-16:00), heating (17:00-24:00), and midnight (00:00-07:30) periods. The highest PM2.5 concentration occurred during the cooking period (236 ± 88 µg m-3), which was characterized by high concentrations of K+ and abundant primary OM-K particles (i.e., organic matter mixed with K-salts) emitted from residential biomass burning. The second highest PM2.5 concentration was found during the heating period (161 ± 97 µg m-3), and the PM2.5 contained abundant spherical primary OM particles (i.e., tarballs) emitted from residential coal burning. The primary emissions from residential solid fuel burning resulted in 75% of the village OM by mass consisting of primary OM and 67% of the village aerosol particles by number internally mixing with primary OM particles. The village PM2.5 composition was different from that of the urban PM2.5, with the former containing more OM (47% vs 32%) and less secondary inorganic ions (30% vs 46%). Individual primary OM-K and tarballs were abundant in the village air. These results suggest a large contribution of village residential emissions in the winter to village air pollution. Our study highlights that the residential health in villages of northern China should be paid more attention because of high PM2.5 concentrations and abundant toxic particles during the cooking and heating periods per day in winter.

Atmospheric fine particles in a typical coastal port of Yangtze River Delta.

In recent decades, coastal ports have experienced rapid development and become an important economic and ecological hub in China. Atmospheric particle is a research hotspot in atmospheric environmental sciences in inland regions. However, few studies on the atmospheric particle were conducted in coastal port areas in China, which indeed suffers atmospheric particle pollution. Lack of the physicochemical characteristics of fine particles serves as an obstacle toward the accurate control for air pollution in the coastal port area in China. Here, a field observation was conducted in an important coastal port city in Yangtze River Delta from March 6 to March 19, 2019. The average PM2.5 concentration was 63.7 ± 27.8 µg/m3 and NO3-, SO42-, NH4+, and organic matter accounted for ~60% of PM2.5. Fe was the most abundant trace metal element and V as the ship emission indicator was detected. Transmission electron microscopy images showed that SK-rich, soot, Fe, SK-soot and SK-Fe were the major individual particles in the coastal port. V and soluble Fe were detected in sulfate coating of SK-Fe particles. We found that anthropogenic emissions, marine sea salt, and secondary atmosphere process were the major sources of fine particles. Backward trajectory analysis indicated that the dominant air masses were marine air mass, inland air mass from northern Zhejiang and inland-marine mixed air mass from Shandong and Shanghai during the sampling period. The findings can help us better understand the physicochemical properties of atmospheric fine particles in the coastal port of Eastern China.

Iron solubility in fine particles associated with secondary acidic aerosols in east China.

Soluble iron (FeS) in aerosols contributes to free oxygen radical generation with implications for human health, and potentially catalyzes sulfur dioxide oxidation. It is also an important external source of micronutrients for ocean ecosystems. However, factors controlling FeS concentration and its contribution to total iron (FeT) in aerosols remain poorly understand. Here, FeS and FeT in PM2.5 was studied at four urban sites in eastern China from 21 to 31 December, 2017. Average FeT (869-1490 ng m-3) and FeS (24-68 ng m-3) concentrations were higher in northern than southern China cities, but Fe solubility (%FeS, 2.7-5.0%) showed no spatial pattern. Correlation analyses suggested %FeS was strongly correlated with FeS and PM2.5 instead of FeT concentrations. Individual particle observations confirmed that more than 65% of nano-sized Fe-containing particles were internally mixed with sulfates and nitrates. Furthermore, there was a high correlation between sulfates or nitrates/FeT molar ratio and %FeS. We also found that the sulfates/nitrates had weaker effects on %FeS at RH < 50% than at RH > 50%, suggesting RH as indirect factor can influence %FeS in PM2.5. These results suggest an important role of chemical processing in enhancing %FeS in the polluted atmosphere.

The potential of proteins, hydrolysates and peptides as growth factors for Lactobacillus and Bifidobacterium: current research and future perspectives.

Probiotics are live microorganisms that provide health benefits to the host when consumed in adequate concentrations. The strains most frequently used as probiotics include Lactobacillus and Bifidobacteria. Probiotics have demonstrated significant potential as therapeutic options for various diseases. In addition to oligosaccharides, proteins, hydrolysates and peptides have also been shown function as prebiotics to promote the growth of probiotics. Therefore, this review provides a summary of the available information and current knowledge on the effects of various proteins on probiotics, focusing on how proteins influence probiotics, although uncertainties and disagreements about how the metabolism of proteins promotes probiotics still exist. Understanding the relationship between proteins and probiotics will allow appropriate prebiotic selection and the development of effective methods to promote the proliferation of probiotics.

Effect of soybean oligopeptide on the growth and metabolism of Lactobacillus acidophilus JCM 1132.

Soybean protein (Pro) and soybean oligopeptide (Pep) were subjected to simulated digestion in vitro to study the effect of Pep on the growth and metabolism of Lactobacillus acidophilus JCM 1132. First, the molecular weight distribution differences of samples before and after digestion were compared, and the samples were used to replace the nitrogen source components in the culture media. Then, the viable cell numbers, lactic acid and acetic acid content, differential metabolites, and metabolic pathways during the culturing process were measured. Results showed that the digested soybean oligopeptide (dPep) was less efficient than MRS medium in promoting the growth, but by increasing the content of the intermediates during the tricarboxylic acid (TCA) cycle, its metabolic capacity was significantly improved. Besides, due to the low molecular weight of dPep, it can be better transported and utilized. And dPep significantly strengthened the amino acid metabolism and weakened the glycerol phospholipid metabolism, so the ability of dPep in promoting the growth and metabolism of Lactobacillus acidophilus JCM 1132 is higher than the digested soybean protein (dPro).

Morphology, composition, and sources of individual aerosol particles at a regional background site of the YRD, China.

Aerosol samples were collected at Lin'an, a background site of Yangtze River Delta (YRD). Morphology, size, composition, and mixing state of individual aerosol particles were characterized by transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDS), and the soluble ions of PM1.0 were studied by aerosol mass spectrometer (AMS). The daily average AMS mass concentrations of sulfate, nitrate, and ammonium were about 5.8, 8.6, and 5.6 µg/m3, respectively. Individual aerosol particles were classified into seven types: S-rich, K-rich, organic matter (OM), soot, fly ash, metal, and mineral. S-rich particles were dominant in all size bins, and 51% (by number) of S-rich particles were internally mixed with other particles. The fraction of organic coating particles was 13.7% in morning, 25.2% in afternoon, and 11% in evening, suggesting that the strong photochemical process during afternoon produced more secondary organic aerosols (SOA) on the surface of inorganic particles. Fly ash and metal particles were abundant during the day, suggesting the influence of emissions from coal-fired power plants and steel plants. The results indicate that the intense industrial emissions in the YRD significantly transported to the background areas. PM2.5 concentration may be lower in background air than in urban air but complex mixing state of aerosol particles indicates that the long-range transported particles substantially influenced the background air quality.