In this study, screening bacteriocin-producing strains from 2,000 plant-derived strains by agar well diffusion method was conducted. The corresponding produced bacteriocin was purified and identified by Sephadex gel chromatography, reversed-phase high-performance liquid chromatography (RP-HPLC), and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Meanwhile, the biological characteristics of bacteriocin were investigated. The targeted strain W3-2 was obtained and identified as Lactobacillus plantarum by morphological observation and 16S rRNA gene sequence analysis. Correspondingly, a novel bacteriocin (named plantaricin W3-2) produced by L. plantarum W3-2 with a molecular weight of 618.26 Da, and an amino acid sequence of AVEEE was separated, purified by Sephadex gel chromatography and RP-HPLC, and identified by LC-MS/MS. Further characteristics analysis displayed that plantaricin W3-2 had good thermal, pH stability, and broad-spectrum antimicrobial ability. In conclusion, plantaricin W3-2 can be used as a new food preservative.

Limosilactobacillus fermentum (L. fermentum) is widely used in industrial food fermentations, and its probiotic and health-promoting roles attracted much attention in the past decades. In this work, the probiotic potential of L. fermentum 664 isolated from Chinese fermented pickles was assessed. In addition, the anti-inflammatory properties and mechanisms were investigated using lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Results indicated that L. fermentum 664 demonstrated excellent acid and bile salt tolerance, adhesion capability, antimicrobial activity, and safety profile. L. fermentum 664 downregulated the release of inflammatory mediators, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and cyclooxygenase-2 (COX-2) stimulated with LPS. Moreover, L fermentum 664 inhibited the nuclear translocation of the nuclear factor κB (NF-κB) and the activation of mitogen-activated protein kinases (MAPKs) induced by LPS. This action was associated with a reduction in reactive oxygen species (ROS) levels and an enhanced expression of heme oxygenase-1 (HO-1) protein. Additionally, whole genome sequencing indicated that L. fermentum 664 contained genes that encode proteins with antioxidant and anti-inflammatory functions, including Cytochrome bd ubiquinol oxidase subunit I (CydA), Cytochrome bd ubiquinol oxidase subunit II (CydB), and NAD(P)H dehydrogenase quinone 1 (NQO1). In conclusion, our study suggested that L. fermentum 664 has the potential to become a probiotic and might be a promising strategy for the prevention of inflammation.

Currently, there is increasing interest in the commercial utilization of probiotics isolated from traditional fermented food products. Therefore, this study aimed to investigate the probiotic potential of Lactiplantibacillus plantarum (L. plantarum) Z22 isolated from naturally fermented mustard. The results suggest that L. plantarum Z22 exhibits good adhesion ability, antibacterial activity, safety, and tolerance to acidic conditions and bile salts. We further determined the anti-inflammatory mechanism and properties of L. plantarum Z22 and found that L. plantarum Z22 could significantly reduce the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the expression of the pro-inflammatory mediator cyclooxygenase-2 (COX-2) protein in LPS-induced RAW 264.7 cells. In addition, L. plantarum Z22 also effectively inhibited the signaling pathways of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs). This effect can be attributed to a decrease in the levels of reactive oxygen species (ROS) and increased heme oxygenase-1 (HO-1) expression. Moreover, whole-genome sequencing revealed that L. plantarum Z22 contains gene-encoding proteins with anti-inflammatory functions, such as beta-glucosidase (BGL) and pyruvate kinase (PK), as well as antioxidant functions, including thioredoxin reductase (TrxR), tyrosine-protein phosphatase, and ATP-dependent intracellular proteases ClpP. In summary, these results indicated that L. plantarum Z22 can serve as a potential candidate probiotic for use in fermented foods such as yogurt (starter cultures), providing a promising strategy for the development of functional foods to prevent chronic diseases.

Fermented minced peppers are a traditional fermented food that has a unique flavor due to various microbial communities involved in fermentation. Understanding the changes in microbial communities and volatile components of fermented minced peppers is particularly important to unveil the formation of unique flavor of fermented peppers. In this study, the microbial communities and volatile compounds in fermented minced pepper was analyzed by high-throughput sequencing and GC-MS, as well as their underlying correlations were also established. Results indicated that 17 genera were identified as dominant microorganisms in the fermentation of minced pepper, accompanied by the detection of 64 volatile compounds. Further hierarchical clustering analysis (HCA) displayed that dynamic change of volatile metabolites were involved in the fermentation process, where alkane volatile components were mainly generated in the early stage (3–5 days), and alcohols volatile components were in the middle stage (7–17 days), while ester volatile components were mainly produced in both the early stage (3–5 days) and last stage (17–20 days). Bidirectional orthogonal partial least squares (O2PLS) analysis revealed that 11 genera were core functional microorganisms of fermented minced pepper. Cladosporium and Hansenpora were significantly correlated with the formation of 9 and 6 volatiles, respectively. These findings provide new insights into aroma profile variation of fermented minced peppers and underlying mechanism of characteristic aroma formation during fermentation.

Lactic acid bacteria (LAB) are commonly consumed as probiotics to improve gut barrier function and boost the immune system. This study aimed to screen LAB with high immunomodulatory activity using RAW264.7 macrophages. According to the results, Limosilactobacillus reuteri AUc2301 was selected from 84 screened strains that can stimulate RAW264.7 cell proliferation. Limosilactobacillus reuteri AUc2301 significantly enhanced the phagocytosis activity of RAW264.7 cells. In the ELISA test, Limosilactobacillus reuteri AUc2301 significantly promoted the release of interleukin-6, IL-1β, the tumor necrosis factor, and nitric oxide in RAW264.7 macrophages. In addition, Limosilactobacillus reuteri AUc2301 significantly inhibited the excessive release of IL-6, IL-1β, TNF-α, prostaglandin E2 as well as NO and the high expression of cyclooxygenase-2 in RAW264.7 macrophages induced by lipopolysaccharide. In further mechanism studies, Limosilactobacillus reuteri AUc2301 could regulate the nuclear factor-κB signaling pathway in RAW264.7 macrophages. Collectively, the screened Limosilactobacillus reuteri AUc2301 showed good immunomodulatory activity in vitro, and it has the potential to be developed as a novel probiotic.