Novel casein-derived immunomodulatory peptide PFPEVFG: Activity assessment, molecular docking, activity site and mechanism of action.

Nowadays, there is still a gap in the knowledge of the structure-activity relationship of immunomodulatory peptides. In this study, PFPEVFG was selected as a peptide with immunomodulatory activity from casein hydrolysate by virtual screening and its immunomodulatory activity was verified by the phagocytosis, proliferation, and expression of cytokines (IL-6, IL-1ß, TNF-α) and chemokines (CXCL1, CXCL2) in RAW 264.7 macrophages. Next, molecular docking and double-stranded small interfering RNA (siRNA) mutually verified that the immunomodulatory activity of PFPEVFG was mediated by TLR2/4. Furthermore, the highest occupied molecular orbital (HOMO) analysis showed that the C19 = O20 site with a HOMO contribution of 32.22988% was its active site, and the phenylalanine, where the C19 = O20 site was located, was its active amino acid. Finally, the combination of pathway inhibitors and Western blot revealed that PFPEVFG activated macrophages through the nuclear factor-κB (NF-κB) signaling pathway. In summary, this study provided a new perspective on deeply understanding the structure-activity relationship of casein-derived immunomodulatory peptides, as well as a further theoretical and technological basis for the application of immunomodulatory peptides.

Exopolysaccharides and Surface-Layer Proteins Expressed by Biofilm-State Lactiplantibacillus plantarum Y42 Play Crucial Role in Preventing Intestinal Barrier and Immunity Dysfunction of Balb/C Mice Infected by Listeria monocytogenes ATCC 19115.

Our previous study showed that Lactiplantibacillus plantarum Y42 in the biofilm state can produce more exopolysaccharides and surface-layer proteins and showed a stronger promoting effect on intestinal barrier function than that in the planktonic state. In this study, oral administration of the live/pasteurized planktonic or biofilm L. plantarum Y42 and its metabolites (exopolysaccharides and surface-layer proteins) increased the expression of Occludin, Claudin-1, ZO-1, and MUC2 in the gut of the Balb/C mice after exposure to Listeria monocytogenes ATCC 19115 and inhibited the activation of the NLRP3 inflammasome pathway, which in turn reduced the levels of inflammatory cytokines IL-1ß and IL-18 in the serum of the mice. Furthermore, oral administration of the live/pasteurized planktonic or biofilm L. plantarum Y42 and its metabolites increased the abundance of beneficial bacteria (e.g., Lachnospiraceae_NK4A136_group and Prevotellaceae_UCG-001) while reducing the abundance of harmful bacteria (e.g., norank_f__Muribaculaceae) in the gut of the mice, in line with the increase of short-chain fatty acids and indole derivatives in the feces of the mice. Notably, biofilm L. plantarum Y42 exerted a better preventing effect on the intestinal barrier dysfunction of the Balb/C mice due to the fact that biofilm L. plantarumY42 expressed more exopolysaccharides and surface-layer proteins than the planktonic state. These results provide data support for the use of exopolysaccharides and surface-layer proteins extracted from biofilm-state L. plantarum Y42 as functional food ingredients in preventing intestinal barrier dysfunction.

Lactiplantibacillus plantarum-Derived Indole-3-lactic Acid Ameliorates Intestinal Barrier Integrity through the AhR/Nrf2/NF-κB Axis.

Our previous studies have shown that Lactiplantibacillus plantarum DPUL-S164-derived indole-3-lactic acid (ILA) ameliorates intestinal epithelial cell barrier injury by activating aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways and promoting tight junction protein expression. This study further explored the crucial substances of L. plantarum DPUL-S164 in alleviating intestinal barrier damage in mice through a dextran sodium sulfate-induced ulcerative colitis mouse model. Compared to dead L. plantarum DPUL-S164 (D-S164), live L. plantarum DPUL-S164 (S164) and its tryptophan metabolite, ILA, showed an effective ameliorating effect on the intestinal barrier injury of mice treated by antibiotic cocktail and sodium dextran sulfate, suggesting that the crucial substances of L. plantarum DPUL-S164 ameliorating intestinal barrier injury are its extracellular metabolites. Furthermore, S164 and its tryptophan metabolite, ILA, ameliorate intestinal barrier injury and suppress intestinal inflammation by activating the AhR-Nrf2 pathway and inhibiting the nuclear factor kappa-B (NF-κB) pathway. These results suggest that L. plantarum DPUL-S164 ameliorates intestinal epithelial barrier damage in mice, primarily by producing ILA as a ligand to activate the AhR pathway.

Oral Administration of Fermented Milk from Co-Starter Containing Lactobacillus plantarum Y44 Shows an Ameliorating Effect on Hypertension in Spontaneously Hypertensive Rats.

Fermented dairy foods such as yogurt exhibit some beneficial effects on consumers, including relieving the symptoms of hypertension. This study aims to obtain fermented dairy products from a co-starter that have a great flavor and the auxiliary function of reducing blood pressure after longtime consumption. Commercial starter cultures composed of Lactobacillus delbrueckii subsp. bulgaricus CICC 6047 and Streptococcus thermophilus CICC 6038 were combined with Lactobacillus plantarum strains Y44, Y12, and Y16, respectively, as a combined starter culture to ferment the mixed milk of skim milk and soybean milk. The fermented milk produced using the combined starter culture mixed with L. plantarum Y44 showed an angiotensin-converting-enzyme (ACE) inhibitory activity (53.56 ± 0.69%). Some peptides that regulate blood pressure were released in the fermented milk, such as AMKPWIQPK, GPVRGPFPII, LNVPGEIVE, NIPPLTQTPV, and YQEPVL. In spontaneously hypertensive rat (SHR) oral-administration experiments compared with the gavage unfermented milk group, the gavage feeding of SHRs with the fermented milk produced using the combined starter culture mixed with L. plantarum Y44 significantly reduced the blood pressure of the SHRs after long-term intragastric administration, shown with the systolic blood pressure (SBP) and diastolic blood pressure (DBP) decreasing by 23.67 ± 2.49 mmHg and 15.22 ± 2.62 mmHg, respectively. Moreover, the abundance of short-chain fatty acids (SCFA), bacterial diversity in the gut microbiota, and SCFA levels including acetic acid, propionic acid, and butyric acid in the feces of the SHRs were increased via oral administration of the fermented milk produced using the combined starter culture containing L. plantarum Y44. Furthermore, the ACE-angiotensin II (Ang II)-angiotensin type 1 (AT 1) axis was downregulated, the angiotensin-converting-enzyme 2 (ACE 2)-angiotensin(1-7) (Ang1-7)-Mas receptor axis of the SHRs was upregulated, and then the RAS signal was rebalanced. The fermented milk obtained from the combined starter culture shows the potential to be a functional food with antihypertension properties.

Exopolysaccharide secreted by Lactiplantibacillus plantarum Y12 showed inhibitory effect on the pathogenicity of Shigella flexneri in vitro and in vivo.

Shigella flexneri is a prevalent foodborne and waterborne pathogen that threatens human health. Our previous research indicated that the Lactiplantibacillus plantarum Y12 exopolysaccharide (L-EPS) potentially inhibited the pathogenicity of S. flexneri. The in vitro results of this study demonstrated that L-EPS effectively mitigated the symptoms induced by S. flexneri in HT-29 cells, including inhibited gene expression levels of IL-1ß, IL-6, IL-8, TNF-α, TLR 2/4, and NOD1/2; decreased apoptosis ratio; and alleviated damage degree of intestinal barrier function (Zona occludens 1, Occludin, and Claudin-1). The in vivo results demonstrated that S. flexneri treated with L-EPS elicited mild adverse physiological manifestations, an inflammatory response, and tissue damage. The infection of S. flexneri caused significant alterations in the abundance of phylum (Firmicutes, Bacteroidota, Actinobacteriota, and Proteobacteria), family (Lachnospiraceae, Muribaculaceae, Rikenellaceae, Prevotellaceaea, Ruminococcaceae, and Lactobaillaceae), and genus (Escherichia Shigella and Lachnospirillaceae NK4A136 group) within the cecal microbiota. These changes were accompanied by perturbations in taurine and hypotaurine metabolism, tricarboxylic acid (TCA) cycle activity, arginine biosynthesis, and histidine metabolic pathways. However, intervention with L-EPS attenuated the dysbiosis of cecal microbiota and metabolic disturbances. In summary, our research suggested a potential application of L-EPS as a functional food additive for mitigating S. flexneri infection.

Lactiplantibacillus plantarum DLPT4 Protects Against Cyclophosphamide-Induced Immunosuppression in Mice by Regulating Immune Response and Intestinal Flora.

In this study, the strain Lactiplantibacillus plantarum DLPT4 was investigated for the immunostimulatory activity in cyclophosphamide (CTX)-induced immunosuppressed BALB/c mice. L. plantarum DLPT4 was administered to BALB/c mice by oral gavage for 30 days, and CTX was injected intraperitoneally from the 25th to the 27th days. Intraperitoneal injection of CTX caused damage to the thymic cortex and intestines, and the immune dysfunction of the BALB/c mice. L. plantarum DLPT4 oral administration exerted immunoregulating effects evidenced by increasing serum immunoglobulin (IgA, IgG, and IgM) levels and reducing the genes expression of pro-inflammatory factors (IL-6, IL-1ß, and TNF-α) of the CTX-induced immunosuppressed mice. The results of the metagenome-sequencing analysis showed that oral administration of L. plantarum DLPT4 could regulate the intestinal microbial community of the immunosuppressed mice by changing the ratio of Lactiplantibacillus and Bifidobacterium. Meanwhile, the abundance of carbohydrate enzyme (CAZyme), immune diseases metabolic pathways, and AP-1/MAPK signaling pathways were enriched in the mice administrated with L. plantarum DLPT4. In conclusion, oral administration of L. plantarum DLPT4 ameliorated symptoms of CTX-induced immunosuppressed mice by regulating gut microbiota, influencing the abundance of carbohydrate esterase in the intestinal flora, and enhancing immune metabolic activity. L. plantarum DLPT4 could be a potential probiotic to regulate the immune response.

Indole-3-Lactic Acid, a Tryptophan Metabolite of Lactiplantibacillus plantarum DPUL-S164, Improved Intestinal Barrier Damage by Activating AhR and Nrf2 Signaling Pathways.

A growing body of evidence suggests that microbial tryptophan metabolites play a crucial role in maintaining intestinal barrier stability and modulating host immunity. Our previous study showed that the Lactiplantibacillus plantarum (L. plantarum ) DPUL-S164 intervention in mice with a high tryptophan (Trp) diet promotes indole-3-lactic acid (ILA) production in the mice's intestinal tract and ameliorates dextran sodium sulfate(DSS)-induced intestinal barrier damage in mice. In this study, we used the HT-29 cell monolayer model to evaluate the effect of the L. plantarum DPUL-S164 Trp metabolites (DPUL-S164-TM) on the intestinal barrier. We found that L. plantarum DPUL-S164-TM alleviated lipopolysaccharide (LPS)-induced intestinal barrier damage and inflammation of the HT-29 cell monolayer by promoting the expression of tight junction proteins (ZO-1, occludin, claudin1), activating the AhR and Nrf2 signaling pathways, and inhibiting the NF-κB signaling pathway. We found that the promotion of tight junction protein expression and the activation of the Nrf2 signaling pathway by L. plantarum DPUL-S164-TM were dependent on the AhR expression of HT-29 cells. Additionally, L. plantarum DPUL-S164-TM showed a dramatic increase in the ILA content. Therefore, we inferred that ILA in L. plantarum DPUL-S164-TM plays a key role in improving the intestinal barrier function and alleviating inflammation.

Exopolysaccharide produced by Lactiplantibacillus plantarum Y12 exhibits inhibitory effect on the Shigella flexneri genes expression related to biofilm formation.

Shigella is a specific enteric pathogen in humans, causing symptoms of bacterial dysentery. The biofilm formation of S. flexneri contributes to the emergence of multidrug resistance and facilitates the establishment of persistent chronic infections. This study investigated the regulatory effects of Lactiplantibacillus plantarum Y12 exopolysaccharide (L-EPS) on gene expression and its spatial hindrance effects in inhibiting the biofilm formation of S. flexneri. The transcriptome analysis revealed a significant impact of L-EPS on the gene expression profile of S. flexneri, with a total of 968 genes showing significant changes (507 up-regulated and 461 down-regulated). The significantly down-regulated KEGG metabolic pathway enriched in phosphotransferase system, Embden-Meyerhf-Parnas, Citrate cycle, Lipopolysaccharide biosynthesis, Cationic antimicrobial peptide resistance, Two-component system. Moreover, L-EPS significantly down-regulated the gene expression levels of fimbriae synthesis (fimF), lipopolysaccharide synthesis (lptE, lptB), anchor protein repeat domain (arpA), virulence factor (lpp, yqgB), antibiotic resistance (marR, cusB, mdtL, mdlB), heavy metal resistance (zraP), and polysaccharide synthesis (mtgA, mdoB, mdoC). The expression of biofilm regulator factor (bssS) and two-component system suppressor factor (mgrB) were significantly up-regulated. The RT-qPCR results indicated that a major component of L-EPS (L-EPS 2-1) exhibited the gene regulatory effect on the S. flexneri biofilm formation. Furthermore, electrophoresis and isothermal microtitration calorimetry demonstrated that the interaction between L-EPS 2-1 and eDNA is electrostatic dependent on the change in environmental pH, disrupting the stable spatial structure of S. flexneri biofilm. In conclusion, L-EPS inhibited the biofilm formation of S. flexneri through gene regulation and spatial obstruction effects.

Changes in Intracellular and Extracellular Metabolites of Mixed Lactobacillus Strains Enhance Inhibition of Pathogenic Bacterial Growth and Lipopolysaccharide-Induced Alleviation of RAW264.7 Cellular Inflammation.

It is important to explore whether there are antagonistic and synergistic effects between different strains of Lactobacillus when developing mixed Lactobacillus strain products. In this study, we investigated the antagonistic and symbiotic effects of co-cultured Lactobacillus strains, as well as their amelioratory effects on lipopolysaccharide (LPS)-induced inflammation and oxidative stress in RAW264.7 cells. The Lactobacillus strains tested in this paper showed no antagonism. Co-culture of Lactiplantibacillus plantarum Y44 and L. plantarum AKS-WS9 was found to show inhibiting effects on the growth of Escherichia coli and Staphylococcus aureus. Additionally, the co-cultured Lactiplantibacillus plantarum Y44 and L. plantarum AKS-WS9 relieved inflammation in RAW264.7 cells induced by LPS by inhibiting the activation of NF-κB and P38 signaling pathways and down-regulating the expression of pro-inflammatory cytokines NO, ROS, iNOs and TNF-α. And the co-cultured Lactobacillus strains activated the Nrf2 signaling pathway in the LPS-induced RAW264.7 cells to promote the expression of antioxidant enzymes in response to oxidative stress. There was a difference in intracellular and extracellular metabolites between single or co-cultured Lactobacillus strains, and the co-cultured Lactobacillus strains significantly increased extracellular metabolites 4-chlorobenzaldehyde, psoromic acid, and 2-dodecylbenzenesulfonic acid and intracellular metabolites 9(S)-HODE, pyocyanin, and LysoPA. We inferred that the better antibacterial and anti-inflammatory ability of the co-cultured Lactobacillus strains were related to the changes in the metabolites of the co-cultured Lactobacillus strains. The co-cultured L. plantarum Y44 and L. plantarum AKS-WS9 strains exhibited better anti-inflammatory abilities and had the potential to alleviate the symptoms of inflammatory diseases as mixed probiotics.

Screening lactic acid bacteria and yeast strains for soybean paste fermentation in northeast of China.

Soybean paste was a traditional fermented product in northeast China, mainly fermented by molds, yeast, Bacillus, and lactic acid bacteria. In this study, the safety and fermentation ability of lactic acid bacteria and yeast strains isolated from traditional soybean paste in northeast China were evaluated, and the dynamic changes of biogenic amines, aflatoxin, total acids, amino acid nitrogen, and volatile compounds were investigated during the fermentation of the traditional soybean paste. Among the tested strains, Lactiplantibacillus plantarum DPUL-J8 could decompose putrescine by 100%, and no biogenic amine was produced by Pichia kudriavzevii DPUY-J8. Lactiplantibacillus plantarum DPUL-J8 and P. kudriavzevii DPUY-J8 with strong biogenic amine degrading capacities were inoculated into the soybean paste. After 30 days of fermentation, the content of biogenic amines and aflatoxin in the fermented soybean paste declined by more than 60% and 50%, respectively. At the same time, compared with the control group without inoculation, the contents of total acid (1.29 ± 0.05 g/100 g), amino acid nitrogen (0.82 ± 0.01 g/100 g), and volatile compounds in soybean paste fermented by L. plantarum DPUL-J8 and P. kudriavzevii DPUY-J8 were significantly increased, which had a good flavor. These results indicated that the use of L. plantarum DPUL-J8 and P. kudriavzevii DPUY-J8 as starter cultures for soybean paste might be a good strategy to improve the safety and flavor of traditional Chinese soybean paste.

Milk fermented by combined starter cultures comprising three Lactobacillus strains exerts an alleviating effect on loperamide-induced constipation in BALB/c mice.

Fermented dairy food, such as yogurt, exhibits some beneficial effects on consumers, including alleviating constipation. In this study, Lactobacillus delbrueckii subsp. bulgaricus DPUL-36, Lactobacillus paracasei DPUL-40 and Lactobacillus paracasei DPUL-44 were used as combined starter cultures at a bacterial cell ratio of 1 : 1 : 1 for reconstituted skim milk fermentation. The milk fermented with the combined starter culture showed good sensory properties. During the storage period, the yogurt showed high lactic acid bacteria vitality and quality stability. Constipated BALB/c mice induced by loperamide (Lop) were orally administered with the combined starter culture fermented milk for 14 days. The results clearly showed that oral administration of the fermented milk relieved Lop-induced constipation in the mice, as evidenced by the significantly increased fecal water content, reduced first black stool time, improved gastrointestinal transmission rate, recovered colon tissue damage, increased level of excitatory neurotransmitters (motilin, gastrin, and substance P) and reduced level of inhibitory neurotransmitters (vasoactive intestinal peptide, somatostatin and endothelin-1) of the mice. Compared with the mice in the Lop group, oral administration of the fermented milk significantly increased the concentrations of acetic acid, propionic acid, butyric acid, isovaleric acid and valeric acid in the feces of the mice, and furthermore, exerted a regulatory effect on the gut microbiota of the mice by up-regulating the abundance of Lactobacillus and Bacteroides, and decreasing the abundance of Helicobacter, Pseudomonas and Porphyromonas. Our results indicated that the combined starter culture fermented milk can effectively alleviate Lop-induced-constipation in BALB/c mice. The relationship between the nutrient profiles and the health promoting function of the yogurt should be further illustrated.

Phenotypic Traits and Probiotic Functions of Lactiplantibacillus plantarum Y42 in Planktonic and Biofilm Forms.

Bacteria in planktonic and biofilm forms exhibit different phenotypic properties. In this study, the phenotypic traits and probiotic functions of Lactiplantibacillus plantarum Y42 in planktonic and biofilm forms were assessed. After 36 h of static culture, scanning electron microscopy and confocal laser scanning microscopy showed that the L. plantarum Y42 bacterial cells contained interconnected adhesive matter on the surface, forming a ~18 µm layer of dense biofilms. The surface properties of L. plantarum Y42 in biofilm form, including autoaggregation ability, hydrophobicity, acid-base charge, and adhesiveness, were all higher than those in the planktonic form. Biofilm L. plantarum Y42 showed a higher tolerance to adverse environmental conditions and a higher survival rate, enzymatic activity, and integrity after vacuum lyophilization. And biofilm L. plantarum Y42 had higher adhesion to human enterocyte HT-29 cell monolayers, inhibited the expressions of proinflammatory factors IL-6 and TNF-α, and promoted the expressions of the anti-inflammatory factor IL-10 and barrier proteins Claudin-1 and Occludin. In addition, L. plantarum Y42 in biofilm form can inhibit the adhesion and invasion of Listeria monocytogenes ATCC 19115 to HT-29 cell monolayers and is more effective in relieving the inflammatory reactions and injuries of HT-29 cells caused by L. monocytogenes ATCC 19115. In conclusion, L. plantarum Y42 in biofilm form exhibited better probiotic functions compared to that in planktonic form. This indicated that L. plantarum Y42 can form biofilms to enhance its probiotic functions, which provided a theoretical basis for better development and utilization of L. plantarum Y42.

Safety evaluation and application of lactic acid bacteria and yeast strains isolated from Sichuan broad bean paste.

Broad bean paste is one of the most popular characteristic traditional fermented bean products in China, which is prepared by mixed fermentation of a variety of microorganisms, among which lactic acid bacteria and yeast played an important role in the improvement of the fermented broad bean paste quality. However, the traditional open-air fermentation of broad bean paste brought some risks of harmful microorganisms. In this study, the safety and fermentation ability of lactic acid bacteria and yeast strains isolated from traditional broad bean paste was evaluated. The results showed that the protease activity of the strain Lactobacillus plantarum DPUL-J5 (366.73 ± 9.00 U/L) and Pichia kudriavzevii DPUY-J5 (237.18 ± 10.93 U/L) were the highest. Both strains produced little biogenic amines, and did not exhibit α-hemolytic activity or antibiotic resistance for some of the antibiotics most used in human medicine. Furthermore, the broad bean paste fermentation involving DPUL-J5 and DPUY-J5 was beneficial for accumulating higher total acid (1.69 ± 0.01 g/100 g), amino-acid nitrogen (0.85 ± 0.03 g/100 g), and more volatile flavor compounds, meanwhile, reducing the levels of biogenic amines and aflatoxin B1. Therefore, this study provided a new strategy to improve the safety and quality of traditional broad bean paste.

Optimization of medium composition of Lactobacillus plantarum Y44 using Plackett-Burman and Box-Behnken designs.

The biomass of Lactobacillus strains depends on the culture media and culture conditions. The purpose of this study was to optimize the culture medium composition and culture conditions of Lactobacillus plantarum Y44 to improve its biomass. The utilization of different carbon sources and nitrogen sources by L. plantarum Y44 was assessed by single factor experiment to screen out the economical carbon and nitrogen sources for L. plantarum Y44 growth. Through optimization experiments, the optimized culture medium for L. plantarum Y44 growth consists of soybean peptone 44.1 g/L, yeast extract 22.1 g/L, sucrose 35.6 g/L, hydrogen diamine citrate 2 g/L, anhydrous sodium acetate 8.5 g/L, dipotassium hydrogen phosphate 4 g/L, Tween-80 2 mL/L, manganese sulfate 0.25 g/L, and magnesium sulfate 0.58 g/L, and the initial pH 6.7. The concentration of viable bacteria cells of L. plantarum Y44 culturing in the optimized medium at 37 °C for 16 h was up to 3.363 × 1010 CFU/mL, as 6.11 times higher than that in the MRS medium.

Saccharomyces cerevisiae I4 Showed Alleviating Effects on Dextran Sulfate Sodium-Induced Colitis of Balb/c Mice.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease. The purpose of this study was to investigate the ameliorating effects of three yeast strains, Saccharomyces cerevisiae I4, Clavispora lusitaniae 30 and Pichia kudriavzevii 11, isolated from traditional fermented dairy food in Xinjiang, China, on the ulcerative colitis symptoms of Balb/c mice treated by dextran sulfate sodium (DSS). Among which, S. cerevisiae I4 had good tolerance to simulated gastrointestinal juice and strong adhesion to HT-29 cells monolayers. Furthermore, the three yeast strains were oral administered to Balb/c mice with DSS induced colitis. The weight loss, colon shortening and histological injury of colitis mice were ameliorated. Then, oral administration of S. cerevisiae I4 improved the immune state by reducing the contents of TNF-α, IL-6 and IL-1ß and increasing immunoglobulin. The relative expression of intestinal barrier proteins Claudin-1, Occludin and Zonula Occludins-1 (ZO-1) of the mice enhanced, and the short chain fatty acids (SCFAs) content such as Propionic acid, Butyric acid, Isobutyric acid and Isovaleric acid in the feces of the mice increased to varying degrees, after S. cerevisiae I4 treatment compared with the model group of drinking 3% DSS water without yeast treatment. Moreover, S. cerevisiae I4 treatment lifted the proportion of beneficial bacteria such as Muribaculaceae, Lactobacillaceae and Rikenellaceae in the intestinal tract of the mice, the abundance of harmful bacteria such as Staphylococcus aureus and Turicibacter was decreased. These results suggested that S. cerevisiae I4 could alleviate DSS induced colitis in mice by enhancing intestinal barrier function and regulating intestinal flora balance.

Lactiplantibacillus plantarum Y42 in Biofilm and Planktonic States Improves Intestinal Barrier Integrity and Modulates Gut Microbiota of Balb/c Mice.

In our previous study, Lactiplantibacillus plantarum Y42 showed some potential probiotic functions and the ability to form biofilm. The aim of this study was to compare the similarities and differences in the probiotic and physiological traits of L. plantarum Y42 in the biofilm and planktonic states. L. plantarum Y42 in the biofilm state was proven to have higher survival after passing through mimic gastrointestinal fluid, as well as excellent adhesion properties on the HT-29 cell monolayers, than those in the planktonic state. The expression of tight junction proteins (TJ proteins) of HT-29 cell monolayers treated by L. plantarum Y42 in the planktonic state increased, while similar changes were not observed in the HT-29 cells treated by the strain in the biofilm state. Furthermore, Balb/c mice were orally administered L. plantarum Y42 in the biofilm and planktonic states, respectively. Compared to the planktonic state, the oral administration of L. plantarum Y42 in the biofilm state significantly boosted IgA levels and improved the immunity of the mice. High-throughput sequencing showed that the diversity and structure of the intestinal flora of the mice were changed after the oral administration of L. plantarum Y42, including the up-regulated relative abundance of Lactobacillus in the intestinal tract of the mice, with no difference between the biofilm and planktonic states. Moreover, oral administration of L. plantarum Y42 in biofilm and planktonic states reduced the release of proinflammatory factors, to a certain extent, in the serum of the mice. The similarities and differences in the probiotic and physiological properties of L. plantarum Y42 in the biofilm and planktonic states can be contributed to the reasonable application of the strain.

Microbial Diversity and Quality-Related Physicochemical Properties of Spicy Cabbage in Northeastern China and Their Correlation Analysis.

Chinese spicy cabbage (CSC) is a popular special fermented food in Northeast China. The bacterial community and quality of CSC from different regions of northeastern China (Group_J: Jilin province, Group_L: Liaoning province, Group_H: Heilongjiang province) at retail (Group_P) and home-made (Group_C) were investigated in this study. The determination of the microbial community was achieved using high-throughput sequencing and the quality-related physicochemical characteristics included pH, salinity, total acid (TA), amino acid nitrogen (AAN), reducing sugar (RS), nitrite, and biogenic amines (BAs). Based on OPLS-DA analysis, there was a difference between the quality of Group_C and Group_P. No significant difference was observed in province grouping. Proteobacteria and Firmicutes were the dominant phyla, and the dominant genera were Lactobacillus, Pantoea, Weissella, and Pseudomonas. All groups had significant differences in community structure (p < 0.05). Compared with Group_C, the relative abundance of opportunistic pathogens (Pseudomonas and Serratia) in Group_P was lower. Pseudomonas and Serratia were the biomarkers in Group_H. At the genus level, Lactobacilluss and Weissella had a positive correlation with pH, Cadaverrine, and salinity (p < 0.05), however, they were negatively related to tryptamine. Pseudomonas was negatively correlated with salinity (p < 0.05). Bacterial community and physicochemical parameters of CSC, as well as the correlation between them, were discussed in this study, providing a reference for future studies on CSC inoculation and fermentation.

Lactiplantibacillus plantarum-12 Alleviates Inflammation and Colon Cancer Symptoms in AOM/DSS-Treated Mice through Modulating the Intestinal Microbiome and Metabolome.

In our previous research, Lactiplantibacillus plantarum-12 alleviated inflammation in dextran sodium sulfate (DSS)-induced mice by regulating intestinal microbiota and preventing colon shortening (p < 0.05). The purpose of the present study was to evaluate whether L. plantarum-12 could ameliorate the colon cancer symptoms of azoxymethane (AOM)/DSS-treated C57BL/6 mice. The results showed that L. plantarum-12 alleviated colonic shortening (from 7.43 ± 0.15 to 8.23 ± 0.25) and weight loss (from 25.92 ± 0.21 to 27.75 ± 0.88) in AOM/DSS-treated mice. L. plantarum-12 oral administration down-regulated pro-inflammatory factors TNF-α (from 350.41 ± 15.80 to 247.72 ± 21.91), IL-8 (from 322.19 ± 11.83 to 226.08 ± 22.06), and IL-1ß (111.43 ± 8.14 to 56.90 ± 2.70) levels and up-regulated anti-inflammatory factor IL-10 (from 126.08 ± 24.92 to 275.89 ± 21.87) level of AOM/DSS-treated mice. L. plantarum-12 oral administration restored the intestinal microbiota dysbiosis of the AOM/DSS treated mice by up-regulating beneficial Muribaculaceae, Lactobacillaceae, and Bifidobacteriaceae levels and down-regulating pathogenic Proteobacteria, Desulfovibrionaceae, and Erysipelotrichaceae levels. As a result, the fecal metabolites of the AOM/DSS-treated mice were altered, including xanthosine, uridine, 3,4-methylenesebacic acid, 3-hydroxytetradecanedioic acid, 4-hydroxyhexanoylglycine, beta-leucine, and glycitein, by L. plantarum-12 oral administration. Furthermore, L. plantarum-12 oral administration significantly ameliorated the colon injury of the AOM/DSS-treated mice by enhancing colonic tight junction protein level and promoting tumor cells death via down-regulating PCNA (proliferating cell nuclear antigen) and up-regulating pro-apoptotic Bax. (p < 0.05). Taken together, L. plantarum-12 oral administration could ameliorate the colon cancer burden and inflammation of AOM-DSS-treated C57BL/6 mice through regulating the intestinal microbiota, manipulating fecal metabolites, enhancing colon barrier function, and inhibiting NF-κB signaling. These results suggest that L. plantarum-12 might be an excellent probiotic candidate for the prevention of colon cancer.

Protecting Effect of Bacillus coagulans T242 on HT-29 Cells Against AAPH-Induced Oxidative Damage.

The aim of the present study was to investigate the in vitro antioxidant potential of Bacillus coagulans T242. B. coagulans T242 showed better antioxidant activities, including the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging ability, lipid peroxidation inhibiting ability and reducing ability, than those exerted by Lactobacillus rhamnosus GG (LGG). B. coagulans T242 positively regulated the expression of the nuclear factor erythroid 2-relatedfactor 2/Kelch-like ECH-associated protein-1 (Nrf2/Keap1) pathway-related proteins (Nrf2, Keap1, heine oxygenase-1 (HO-1)); increased antioxidant enzymes (glutathione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD)); reduced the content of malondialdehyde (MDA) level; decreased the expression of inflammatory-related cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α); and thus increased the survival rate in 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-damaged HT-29 cells. This study proved that B. coagulans T242 exerted antioxidative effects by quenching oxygen free radicals and activating the Nrf2 signaling pathway in HT-29 cells.

Exopolysaccharide Produced by Lactiplantibacillus plantarum-12 Alleviates Intestinal Inflammation and Colon Cancer Symptoms by Modulating the Gut Microbiome and Metabolites of C57BL/6 Mice Treated by Azoxymethane/Dextran Sulfate Sodium Salt.

Exopolysaccharide produced by Lactiplantibacillus plantarum-12 (LPEPS) exhibited the anti-proliferating effect on human colon cancer cell line HT-29 in vitro. The purpose of the study was to determine the alleviating effects of LPEPS on colon cancer development of the C57BL/6 mice treated by azoxymethane/dextran sulfate sodium salt (AOM/DSS). The C57BL/6 mice treated by AOM/DSS were orally administered LPEPS daily for 85 days. The results showed that LPEPS oral administration enhanced colon tight-junction protein expression and ameliorated colon shortening and tumor burden of the AOM/DSS treated mice. Furthermore, LPEPS oral administration significantly reduced pro-inflammatory factors TNF-α, IL-8, and IL-1ß levels and increased anti-inflammatory factor IL-10 level in the serum of the AOM/DSS-treated mice. LPEPS oral administration reversed the alterations of gut flora in AOM/DSS-treated mice, as evidenced by the increasing of the abundance of Bacteroidetes, Bacteroidetes/Firmicutes ratio, Muribaculaceae, Burkholderiaceae, and norank_o__Rhodospirillales and the decreasing of the abundance of Firmicutes, Desulfovibrionaceae, Erysipelotrichaceae, and Helicobacteraceae. The fecal metabolites of the AOM/DSS-treated mice were altered by LPEPS oral administration, involving lipid metabolism and amino acid metabolism. Together, these results suggested that LPEPS oral administration alleviated AOM/DSS-induced colon cancer symptoms of the C57BL/6 mice by modulating gut microbiota and metabolites, enhancing intestine barrier, inhibiting NF-κB pathway, and activating caspase cascade.