Surfactin Mitigates Dextran Sodium Sulfate-Induced Colitis and Behavioral Disorders in Mice by Mediating Gut–Brain-Axis Balance

Ulcerative colitis (UC) is associated with brain neurotransmitter disorders and intestinal dysbiosis. Bacillus amyloliquefaciens fmb50 produces the lipopeptide surfactin, which has a wide range of biological activities. However, the effects of surfactin on DSS-induced colitis have not been reported. In the present study, oral surfactin significantly ameliorated colitis in a mouse model and reduced depression-like behavior, such as slowed walking speed, shortened movement distance in the open field test, and weakened exploration ability in the light–dark shuttle test. Surfactin noticeably improved gut microbial dysbiosis, intestinal barrier dysfunction in the colon, and blood–brain barrier dysfunction in the brain. Furthermore, the colon levels of occludin were upregulated by 68.51%, and the brain levels of occludin and ZO-1 were upregulated by 77.81% and 36.42%, respectively. Surfactin supplementation also inhibited inflammatory responses by inactivating the tumor necrosis factor-α (TNF-α), nuclear factor kappa-B (NF-κB), and NLRP3 signaling pathways in the colon and brain. Thus, we believe that surfactin improved the behavioral disorders by upregulating the levels of 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), norepinephrine (NE), and brain-derived neurotrophic factor (BDNF), suppressing the inflammatory responses, and improving the blood–brain barrier dysfunction. Surfactin also reduced the abundances of gut microbes that are related to colitis, especially targeting facultative anaerobes of the phylum Proteobacteria, and it increased the abundance of beneficial bacteria such as Lactobacillus and unidentified Prevotella. Combined with its nontoxic nature observed in this long-term study in mice, oral surfactin might be a promising intervention strategy for preventing colitis by acting on the microbiota-gut–brain axis

A Novel Class IIb Bacteriocin-Plantaricin EmF Effectively Inhibits Listeria monocytogenes and Extends the Shelf Life of Beef in Combination with Chitosan

Plantaricin EmF separated and identified from L. plantarum 163 was a novel class IIb bacteriocin. The molecular masses of plantaricin Em and F were 1638 and 3702 Da, respectively, with amino acid sequences FNRGGYNFGKSVRH and VFHAYSARGVRNNYKSAVGPADWVISAVRGFIHG, respectively. Plantaricin EmF not only exhibited broad-pH adaptability and thermostability but also showed high efficiency and broad-spectrum antibacterial activity. Its mode of action on L. monocytogenes damaged cell membrane integrity, resulting in the leakage of cytoplasm, changes in cell structure and morphology, and ultimately cell death. Additionally, plantaricin EmF inactivated L. monocytogenes in beef, effectively improving the quality indices of beef, thereby extending its shelf life, especially in combination with chitosan. Plantaricin EmF + 1.0% chitosan extended the shelf life of beef to 15 d, demonstrating its potential application value to replace chemical preservatives to control food-borne pathogenic microorganisms and extend the shelf life of meat and meat products in agriculture and the food industry

Separation, characterization and anti-inflammatory activities of galactoglycerolipids from <i>Perilla frutescens</i> (L.) Britton

The study was to optimize the separation procedures, characterize the galactoglycerolipids and explore their anti-inflammatory activities. Two monogalactosyldiacylglycerols (MGDGs) and three digalactosyldiacylglycerols (DGDGs) from Perilla frutescens (L.) Britton were obtained through one-step silica gel column chromatography and preparative high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD). The presence of additional MGDG (1-O-9Z,12Z,15Z-octadecatrienoyl-2-O-7Z,10Z,13Z-hexadecatrienoyl-3-O-(β-D-galactopyranosyl)-sn-glycerol) and DGDG (1-O-9Z,12Z-octadecadienoyl-2-O-9Z,12Z,15Z-octadecatrienoyl-3-O-(β-D-galactopyranosyl-(1'→6'')-α-D-galactopyranosyl)-sn-glycerol) was concluded for the first time in perilla, by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR). In lipopolysaccharide (LPS)-induced RAW264.7 cells, five galactoglycerolipids exhibited good inhibitory activities against nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) gene expression in a dose-dependent manner, suggesting that fatty acid chain length and unsaturation degree affected their anti-inflammatory activities.</p

TetR-Type Regulator Lp_2642 Positively Regulates Plantaricin EF Production Based on Genome-Wide Transcriptome Sequencing of Lactiplantibacillus plantarum 163

Whole-genome and transcriptome sequences of Lactiplantibacillus plantarum 163 are provided. There was one circular chromosome and four circular plasmids, with sizes of 3,131,367; 56,674; 49,140; 43,628; and 36,387 bp, respectively, in L. plantarum 163. The regulator Lp_2642 was selected from the genome data, the overexpression of which increased the transcriptional levels of related genes in plantaricin EF biosynthesis and enhanced plantaricin EF production. Its production was 17.30 mg/L in 163 (Lp_2642), which was 1.29-fold higher than that of the original strain. The regulation mechanism demonstrated that Lp_2642 can bind to three sites of plnA promoter, which enhances its transcription and expression, thereby increasing plantaricin EF production. Amino acids Asn-100, Asn-64, and Thr-69 may play a key role in the binding of Lp_2642. These results provide a novel strategy for mass production of plantaricin EF, which facilitates its large-scale production and application in the agriculture and food industries as a preservative

Lactobacillus acidophilus NX2‑6 Improved High-Fat Diet-Induced Glucose Metabolism Disorder Independent of Promotion of Insulin Secretion in Mice

High-fat diet (HFD) contributes to metabolic inflammation and glucose metabolism disorder, thereby resulting in the pathogenesis of metabolic syndrome. Accumulating evidence has revealed that some probiotics could improve HFD-induced metabolic inflammation and glucose metabolism disorder. Our previous study has discovered that Lactobacillus acidophilus NX2-6 exhibited in vitro lipid-lowering, antioxidative, and anti-inflammatory activities. This study mainly investigated whether L. acidophilus NX2-6 improved HFD-induced glucose metabolism disorder. The results exhibited that L. acidophilus NX2-6 effectively reduced blood glucose levels and improved glucose tolerance by activating the insulin signaling pathway, promoting glucose uptake, glycolysis, and intestinal gluconeogenesis and suppressing hepatic gluconeogenesis, independent of regulation of glycogen synthesis in the liver and muscle. Enhanced insulin sensitivity was associated with L. acidophilus NX2-6-mediated suppression of inflammatory cascades in the target organs. Meanwhile, L. acidophilus NX2-6 also improved hepatic energy metabolism via the FGF21/AMPKα/PGC-1α/NRF1 pathway. However, L. acidophilus NX2-6 did not affect apoptosis, pyroptosis, inflammation, and endoplasmic reticulum stress in the pancreas of HFD-fed mice. In conclusion, our results indicated that L. acidophilus NX2-6 improved glucose metabolism disorder through enhancing insulin sensitivity, suppressing metabolic inflammation, and promoting energy expenditure

Purification and Characterization of Plantaricin JLA-9: A Novel Bacteriocin against Bacillus spp. Produced by Lactobacillus plantarum JLA‑9 from Suan-Tsai, a Traditional Chinese Fermented Cabbage

Bacteriocins are ribosomally synthesized peptides with antimicrobial activity produced by numerous bacteria. A novel bacteriocin-producing strain, Lactobacillus plantarum JLA-9, isolated from Suan-Tsai, a traditional Chinese fermented cabbage, was screened and identified by its physiobiochemical characteristics and 16S rDNA sequence analysis. A new bacteriocin, designated plantaricin JLA-9, was purified using butanol extraction, gel filtration, and reverse-phase high-performance liquid chromatography. The molecular mass of plantaricin JLA-9 was shown to be 1044 Da by MALDI-TOF-MS analyses. The amino acid sequence of plantaricin JLA-9 was predicted to be FWQ­KMS­FA by MALDI-TOF-MS/MS, which was confirmed by Edman degradation. This bacteriocin exhibited broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria, especially Bacillus spp., high thermal stability (20 min, 121 °C), and narrow pH stability (pH 2.0–7.0). It was sensitive to α-chymotrypsin, pepsin, alkaline protease, and papain. The mode of action of this bacteriocin responsible for outgrowth inhibition of Bacillus cereus spores was studied. Plantaricin JLA-9 had no detectable effects on germination initiation over 1 h on monitoring the hydration, heat resistance, and 2,6-pyridinedicarboxylic acid (DPA) release of spores. Rather, germination initiation is a prerequisite for the action of plantaricin JLA-9. Plantaricin JLA-9 inhibited growth by preventing the establishment of oxidative metabolism and disrupting membrane integrity in germinating spores within 2 h. The results suggest that plantaricin JLA-9 has potential applications in the control of Bacillus spp. in the food industry

Probiotic Yogurt Alleviates High-Fat Diet-Induced Lipid Accumulation and Insulin Resistance in Mice via the Adiponectin Pathway

A high-fat diet (HFD) easily contributes to the pathogenesis of obesity and insulin resistance. Obesity and insulin resistance have been clinical and public health challenges all over the world. Probiotic-fermented yogurt is one type of popular and functional beverage in people’s daily lives. This study mainly explored the lipid- and glucose-lowering effects of Lactobacillus acidophilus NX2-6-fermented yogurt (LA-Y) in HFD-fed mice. The results showed that LA-Y administration improved the lipid profile in the serum and liver, reduced fasting blood glucose levels, and enhanced insulin sensitivity. Protein analysis showed that LA-Y treatment promoted fatty acid oxidation and suppressed de novo lipogenesis in the adipose tissue and liver. LA-Y effectively alleviated glucose metabolism disorders by activating the insulin signaling pathway, suppressing gluconeogenesis in the liver and muscle, reducing the concentration of pro-inflammatory cytokines in the serum, and promoting glycolysis and gluconeogenesis in the small intestine. LA-Y supplementation also promoted fat browning via the adiponectin/AMPKα/PGC-1α/UCP1 pathway and enhanced mitochondrial biogenesis in the liver and muscle by activating the adiponectin/AdipoR1/APPL1/AMPKα/PGC-1α pathway, leading to increased energy expenditure. Therefore, LA-Y may be a functional dairy food for preventing and alleviating diet-induced metabolic disorders

Knockout of <i>rapC</i> Improves the Bacillomycin D Yield Based on <i>De Novo</i> Genome Sequencing of Bacillus amyloliquefaciens fmbJ

Bacillus amyloliquefaciens, a Gram-positive and soil-dwelling bacterium, could produce secondary metabolites that suppress plant pathogens. In this study, we provided the whole genome sequence results of B. amyloliquefaciens fmbJ, which had one circular chromosome of 4 193 344 bp with 4249 genes, 87 tRNA genes, and 27 rRNA genes. In addition, fmbJ was found to contain several gene clusters of antimicrobial lipopeptides (bacillomycin D, surfactin, and fengycin), and bacillomycin D homologues were further comprehensively identified. To clarify the influence of <i>rapC</i> regulating the synthesis of lipopeptide on the yield of bacillomycin D, <i>rapC</i> gene in fmbJ was successfully deleted by the marker-free method. Finally, it was found that the deletion of <i>rapC</i> gene in fmbJ significantly improved bacillomycin D production from 240.7 ± 18.9 to 360.8 ± 30.7 mg/L, attributed to the increased the expression of bacillomycin D synthesis-related genes through enhancing the transcriptional level of <i>comA</i>, <i>comP</i>, and <i>phrC</i>. These results showed that the production of bacillomycin D in B. amyloliquefaciens fmbJ might be regulated by the RapC–PhrC system. The findings are expected to advance further agricultural application of Bacillus spp. as a promising source of natural bioactive compounds

Table1_Improved catalytic performance and molecular insight for lipoxygenase from Enterovibrio norvegicus via directed evolution.DOCX

Lipoxygenase (LOX) holds significant promise for food and pharmaceutical industries. However, albeit its application has been hampered by low catalytic activity and suboptimal thermostability. To address the drawbacks, a directed evolution strategy was explored to enhance the catalytic activity and thermostability of LOX from Enterovibrio norvegicus (EnLOX) for the first time. After two rounds of error-prone polymerase chain reaction (error-prone PCR) and one generations of sequential DNA shuffling, all of four different mutants showed a significant increase in the specific activity of EnLOX, ranging from 132.07 ± 9.34 to 330.17 ± 18.54 U/mg. Among these mutants, D95E/T99A/A121H/S142N/N444W/S613G (EAHNWG) exhibited the highest specific activity, which was 8.25-fold higher than the wild-type enzyme (WT). Meanwhile, the catalytic efficiency (Kcat/Km) of EAHNWG was also improved, which was 13.61 ± 1.67 s−1 μM−1, in comparison to that of WT (4.83 ± 0.38 s−1 μM−1). In addition, mutant EAHNWG had a satisfied thermostability with the t1/2,50 °C value of 6.44 ± 0.24 h, which was 0.4 h longer than that of the WT. Furthermore, the molecular dynamics simulation and structural analysis demonstrated that the reduction of hydrogen bonds number, the enhancement of hydrophobic interactions in the catalytic pocket, and the improvement of flexibility of the lid domain facilitated structural stability and the strength of substrate binding capacity for improved thermal stability and catalytic efficiency of mutant LOX after directed evolution. Overall, these results could provide the guidance for further enzymatic modification of LOX with high catalytic performance for industrial application.</p

Purification, Characterization, and Mode of Action of Plantaricin GZ1-27, a Novel Bacteriocin against <i>Bacillus cereus</i>

Bacillus cereus is an opportunistic pathogen that causes foodborne diseases. We isolated a novel bacteriocin, designated plantaricin GZ1-27, and elucidated its mode of action against B. cereus. Plantaricin GZ1-27 was purified using ammonium sulfate precipitation, gel-filtration chromatography, and RP-HPLC. MALDI-TOF/MS revealed that its molecular mass was 975 Da, and Q-TOF-MS/MS analysis predicted the amino acid sequence as VSGPAGPPGTH. Plantaricin GZ1-27 showed thermostability and pH stability. The antibacterial mechanism was investigated using flow cytometry, confocal laser-scanning microscopy, scanning and transmission electron microscopy, and RT-PCR, which revealed that GZ1-27 increased cell membrane permeability, triggered K+ leakage and pore formation, damaged cell membrane integrity, altered cell morphology and intracellular organization, and reduced the expression of genes related to cytotoxin production, peptidoglycan synthesis, and cell division. These results suggest that plantaricin GZ1-27 effectively inhibits B. cereus at both the cellular and the molecular levels and is a potential natural food preservative targeting B. cereus